JP5220646B2 - Control means for series resonant converter - Google Patents

Description

  The present invention relates to a control unit for a series resonant converter.

  Conventionally, a series resonant converter has been used as a switching power supply device (see, for example, Patent Document 1).

  FIG. 14 is a circuit diagram of a series resonant converter 100 according to a conventional example. The series resonant converter 100 includes a transformer T, switching elements Q1, Q2, capacitors C1, C2, C3, an inductor L1, diodes D1, D2, a first control unit 111, and a second control unit 131. And an insulating part 141.

  One end of the inductor L1 is connected to one end of the primary winding T1 of the transformer T. The other end of the inductor L1 is connected to the input terminal IN1 via the capacitor C1 and to the input terminal IN2 via the capacitor C2. A positive electrode of a DC power source (not shown) is connected to the input terminal IN1, and a negative electrode of a DC power source (not shown) is connected to the input terminal IN2.

  The switch elements Q1 and Q2 are composed of N-channel MOSFETs, and are turned on when the gate-source voltage becomes VGH, and turned off when the gate-source voltage becomes VGL. The input terminal IN1 is connected to the drain of the switch element Q1, and the first controller 111 is connected to the gate of the switch element Q1. The input terminal IN2 is connected to the source of the switch element Q2, and the first controller 111 is connected to the gate of the switch element Q2. Further, the other end of the primary winding T1 of the transformer T is connected to the source of the switch element Q1 and the drain of the switch element Q2. The switch element Q1 and the switch element Q2 are connected in series. A half-bridge circuit is formed.

  The cathode of the diode D1 is connected to one end of the first secondary winding T2 of the transformer T, and the output terminal OUT1 is connected to the other end of the first secondary winding T2 of the transformer T. The output terminal OUT2 is connected to the anode of the diode D1.

  The cathode of the diode D2 is connected to one end of the second secondary winding T3 of the transformer T, and the output terminal OUT1 is connected to the other end of the second secondary winding T3 of the transformer T. The output terminal OUT2 is connected to the anode of the diode D2.

  The output terminal OUT1 and the output terminal OUT2 are connected via a capacitor C3, and the second control unit 131 is connected to the output terminals OUT1 and OUT2. The first control unit 111 is connected to the second control unit 131 via the insulating unit 141.

  The above series resonant converter 100 operates as follows.

  The second control unit 131 outputs a drive signal based on the potential of the output terminal OUT1 and the potential of the output terminal OUT2, and this drive signal is supplied to the first control unit 111 via the insulating unit 141. The first control unit 111 supplies a control signal to the gates of the switch elements Q1 and Q2 based on this drive signal, that is, based on the potential of the output terminal OUT1 and the potential of the output terminal OUT2, thereby causing the switch element Q1 to The procedure of turning on the switch element Q2 and turning off the switch element Q2 and the procedure of turning off the switch element Q1 and turning on the switch element Q2 are alternately performed.

  During a period in which the switch element Q1 is turned on and the switch element Q2 is turned off, the current output from the input terminal IN1 is supplied to the other end of the primary winding T1 of the transformer T via the switch element Q1 in the on state. And flows to the input terminal IN2 via the inductor L1 and the capacitor C2. For this reason, a current flows from the other end of the primary winding T1 of the transformer T to one end, and a magnetic field corresponding to this current is generated around the primary winding T1 of the transformer T. Then, the first secondary winding T2 of the transformer T and the second secondary winding T3 of the transformer T correspond to the magnetic field generated around the primary winding T1 of the transformer T by electromagnetic induction. However, these electromotive forces are rectified by the diodes D1 and D2. As a result, there is a potential difference between the output terminal OUT1 and the output terminal OUT2 so that current flows from the output terminal OUT1 toward the output terminal OUT2 via the diode D1 and the first secondary winding T2 of the transformer T. As a result, a voltage is output from these output terminals OUT1 and OUT2. The voltage output from the output terminals OUT1 and OUT2 is smoothed by the capacitor C3.

  On the other hand, during the period when the switch element Q1 is turned off and the switch element Q2 is turned on, the current output from the input terminal IN1 is connected to one end of the primary winding T1 of the transformer T via the capacitor C1 and the inductor L1. And flows to the input terminal IN2 through the switch element Q2 in the on state. For this reason, a current flows from one end of the primary winding T1 of the transformer T to the other end, and a magnetic field corresponding to this current is generated around the primary winding T1 of the transformer T. Then, the first secondary winding T2 of the transformer T and the second secondary winding T3 of the transformer T correspond to the magnetic field generated around the primary winding T1 of the transformer T by electromagnetic induction. However, these electromotive forces are rectified by the diodes D1 and D2. As a result, there is a potential difference between the output terminal OUT1 and the output terminal OUT2 so that current flows from the output terminal OUT1 toward the output terminal OUT2 via the diode D2 and the second secondary winding T3 of the transformer T. As a result, a voltage is output from these output terminals OUT1 and OUT2. The voltage output from the output terminals OUT1 and OUT2 is smoothed by the capacitor C3.

JP-A-9-308243

  As described above, in the series resonant converter 100, the first control unit 111 turns on the switch element Q1 and turns off the switch element Q2 based on the potential of the output terminal OUT1 and the potential of the output terminal OUT2. And the procedure for turning the switch element Q1 off and the switch element Q2 on are alternately performed. Here, when the series resonant converter 100 performs these two procedures within the frequency range determined by the impedance characteristics of the resonant circuit including the primary winding T1 of the transformer T, the inductor L1, and the capacitor C1 or the capacitor C2. The switch element Q2 is turned on when a current flows through the body diode (not shown) of the switch element Q1, or the switch element Q1 when a current flows through the body diode (not shown) of the switch element Q2. Does not fall out of resonance, such as turning on.

  However, if the above-described two procedures are performed at a frequency lower than the lower limit frequency of the above-described frequency range, the resonance is lost, and an excessive current flows through the switch element Q1 and the switch element Q2. The switch element Q2 may be damaged.

  In view of the above-described problems, an object of the present invention is to provide a control unit for a series resonance converter that can prevent a resonance loss.

The present invention proposes the following items in order to solve the above-described problems.
(1) In the present invention, a first voltage or a second voltage is applied to a transformer, an inductor and a capacitor connected in series with a primary winding of the transformer, a primary winding of the transformer, the inductor, and the capacitor. Voltage applying means for applying, and rectifying and smoothing means configured to rectify and smooth the voltage of the secondary winding of the transformer, the first rectifying element and the second rectifying element being alternately conducted. In the series resonant converter, the control means for controlling the voltage application means, and detects whether or not a current flows through the first rectifier element and whether or not a current flows through the second rectifier element. A current detection unit that controls the voltage application unit to apply the first voltage to the primary winding of the transformer, the inductor, and the capacitor; When the second voltage is applied to the transformer primary winding, the inductor, and the capacitor by controlling the voltage application means, the second rectifier element is turned on, and the current detection unit When it is detected that a current flows through the first rectifying element, the voltage application unit is controlled to stop application of the second voltage to the primary winding of the transformer, the inductor, and the capacitor, When the current detecting unit detects that the current flows through the second rectifier element, the voltage application unit is controlled to apply the first voltage to the primary winding of the transformer, the inductor, and the capacitor. The control means of the series resonance converter characterized by stopping is proposed.

  According to the present invention, in the series resonant converter, when the first voltage is applied to the primary winding of the transformer, the inductor, and the capacitor, the first rectifying element is conducted, and the primary winding of the transformer and the inductor When the second voltage is applied to the capacitor and the capacitor, the second rectifier element becomes conductive. For the series resonant converter, the control means for controlling the voltage applying means for applying the first voltage or the second voltage is used to determine whether or not current has flown through the first rectifier element, and whether or not current has passed through the second rectifier element. A current detection unit for detecting whether or not it has flowed is provided. Then, when the control unit detects that the current has flowed to the first rectifying element by the current detecting unit, the application of the second voltage by the voltage applying unit is stopped, and the current detecting unit supplies the current to the second rectifying element. When it is detected that the current flows, the application of the first voltage by the voltage applying means is stopped.

  Here, when the resonance is lost, before the occurrence, the current starts to flow through the first rectifying element and the second rectifying element that do not flow during steady operation. Of the first rectifying element and the second rectifying element, the current that does not flow during steady operation is the second rectifying element during the period in which the first voltage is applied by the voltage applying means. In the period during which the second voltage is applied by the applying means, it means the first rectifying element.

  Therefore, when the current flows through the first rectifying element by the control means, the application of the second voltage is stopped, and when the current flows through the second rectifying element, the application of the first voltage is stopped. It is possible to prevent loss of resonance.

  Further, in the past, since it is not known when the resonance detachment occurs, there is a case where the resonance detachment is prevented by switching the period for applying the first voltage and the period for applying the second voltage early. . In this case, the period for applying the first voltage and the period for applying the second voltage are shortened, and if the input voltage is lowered, a desired voltage may not be output. However, in the present invention, it can be determined that a resonance loss occurs when a current flows through the first rectifying element or the second rectifying element that does not flow during steady operation. For this reason, it is possible to lengthen the period during which the first voltage is applied and the period during which the second voltage is applied, as compared with the prior art, while preventing loss of resonance. Therefore, there is a case where a desired voltage can be output even if the input voltage is lowered so that the desired voltage cannot be output conventionally.

  In addition, by connecting an electrolytic capacitor in parallel with the power supply that supplies the input voltage to the series resonant converter, the power stored in the electrolytic capacitor can be used for a certain period of time, even if no power is supplied from the power supply. In some cases, a desired voltage is output. In this case, since the stop voltage is set higher than the lower limit value of the input voltage at which a desired voltage can be output in order to prevent the resonance from being lost, the capacity of the electrolytic capacitor was set to be larger. . However, in the present invention, it is possible to prevent loss of resonance without considering the capacitance of the electrolytic capacitor. For this reason, compared with the conventional case, by making the capacitance of the electrolytic capacitor the same, a desired voltage can be output for a longer time. Alternatively, a desired voltage can be output for the same period even if the number of electrolytic capacitors is reduced or the capacity is reduced as compared with the conventional case. Or, compared to the conventional case, even if the number of turns of the primary winding of the transformer is increased or the number of turns of the secondary winding of the transformer is reduced, a desired voltage can be output only during the same period, so that the series resonance The effective current value flowing through each element provided in the converter can be reduced, and high efficiency can be realized.

  (2) The present invention includes a transformer, a capacitor connected in series with the primary winding of the transformer, an inductor connected in series with the secondary winding of the transformer, the primary winding of the transformer and the inductor Voltage applying means for applying the first voltage or the second voltage to the capacitor and the first rectifying element and the second rectifying element that are alternately conducted, and the voltage of the secondary winding of the transformer And a rectifying / smoothing means for rectifying and smoothing the control circuit, the control means for controlling the voltage applying means, whether or not a current flows through the first rectifying element, and the second A current detection unit configured to detect whether or not a current flows through the rectifying element, and controls the voltage application unit to apply the first voltage to the primary winding of the transformer, the inductor, and the capacitor; In this case, when the first rectifying element is conductive and the voltage application means is controlled to apply the second voltage to the primary winding of the transformer, the inductor, and the capacitor, When the current detecting unit detects that a current flows through the first rectifying element, the voltage application unit is controlled to control the primary winding of the transformer, the inductor, and the capacitor. And the current detection unit detects that a current has flown through the second rectifier element, and controls the voltage application means to control the primary winding of the transformer and the A control means for a series resonant converter is proposed, which stops applying the first voltage to the inductor and the capacitor.

  According to the present invention, the inductor connected in series to the primary winding of the transformer in the series resonant converter of (1) is connected in series to the secondary winding of the transformer. According to this, the same effect as (1) can be produced.

  (3) The present invention relates to the control means of the series resonant converter according to (1) or (2), wherein the current detection unit includes a voltage at both ends of the first rectifier element and a voltage at both ends of the second rectifier element. The control means of the series resonance converter characterized by providing the voltage detection part which detects a voltage is proposed.

  According to this invention, the voltage detector for detecting the voltage across the first rectifier element and the voltage across the second rectifier element is provided in the current detector.

  Here, when a current flows through the first rectifying element, the voltage at both ends of the first rectifying element becomes a predetermined value, and when a current flows through the second rectifying element, The voltage at both ends becomes a predetermined value. Therefore, by detecting the voltage across the first rectifier element and the voltage across the second rectifier element by the voltage detection unit, whether or not a current flows through the first rectifier element, It is possible to detect whether or not a current flows through the rectifying element 2.

  (4) In the present invention, in the control means for the series resonant converter according to any one of (1) to (3), the current detection unit detects that a current has flowed to the first rectifier element, and the voltage application When the application of the second voltage to the primary winding of the transformer, the inductor, and the capacitor is stopped by controlling the means, the primary winding of the transformer and the inductor are controlled by controlling the voltage application means. And a first period for applying the first voltage to the capacitor is set to be the same as a period during which the second voltage is applied, and the current detector causes a current to flow through the second rectifier element. When the application of the first voltage to the primary winding of the transformer, the inductor, and the capacitor is stopped by detecting the flow and controlling the voltage application means, the voltage application means is controlled. The above A second period during which the second voltage is applied to the primary winding of the inductor, the inductor, and the capacitor is set to be the same as a period during which the first voltage is applied. The control means of the resonant converter is proposed.

  According to the present invention, the current detector detects that the current has flown through the first rectifier element, and controls the voltage application means to apply the second voltage to the primary winding, inductor, and capacitor of the transformer. When the operation is stopped, the first period in which the voltage application means is controlled to apply the first voltage to the primary winding, inductor, and capacitor of the transformer is the same as the period in which the second voltage was applied. It was decided to set. Further, when the current detector detects that the current has flown through the second rectifying element and controls the voltage application means to stop the application of the first voltage to the transformer primary winding, inductor and capacitor. The second period of applying the second voltage to the primary winding, inductor and capacitor of the transformer by controlling the voltage applying means is set to be the same as the period during which the first voltage was applied. It was supposed to be a feature.

  For this reason, even when the application of the first voltage or the second voltage is stopped based on the detection result by the current detection unit, the time during which the first voltage is applied and the time during which the second voltage is applied The difference can be prevented from occurring. Accordingly, it is possible to prevent the partial excitation of the transformer, which is caused by a difference between the time during which the first voltage is applied and the time during which the second voltage is applied.

  (5) In the present invention, a first voltage or a second voltage is applied to the transformer, the inductor and the capacitor connected in series with the primary winding of the transformer, and the primary winding, the inductor, and the capacitor of the transformer. Voltage applying means to be applied, first and second rectifying elements alternately conducting, a first switch element connected in parallel with the first rectifying element, and a parallel with the second rectifying element And a rectifying / smoothing means configured to rectify and smooth the voltage of the secondary winding of the transformer, and to control the voltage applying means. Control means for determining whether a current flows through the first rectifier element, whether a current flows through the second rectifier element, or whether a current flows through the first switch element. A current detection unit configured to detect whether or not a current flows through the second switch element; and controlling the voltage application unit to apply the first voltage to the primary winding of the transformer, the inductor, and the capacitor. When applied, the first rectifier element becomes conductive and a current flows through the first switch element, and the voltage applying means is controlled to control the primary winding of the transformer, the inductor, and the capacitor. When the second voltage is applied to the second rectifier element, the second rectifier element becomes conductive and a current flows through the second switch element, and the current detector detects the first rectifier element or the first rectifier element. When it is detected that a current flows through the switch element, the voltage application means is controlled to stop the application of the second voltage to the primary winding of the transformer, the inductor, and the capacitor. When the current detection unit detects that a current flows through the second rectifier element or the second switch element, the voltage application unit is controlled to control the primary winding of the transformer, the inductor, and the capacitor. The control means of the series resonance converter characterized by stopping the application of the first voltage to is proposed.

  According to the present invention, in the series resonant converter, when the first voltage is applied to the primary winding of the transformer, the inductor, and the capacitor, the first rectifier element is turned on and the current is supplied to the first switch element. When the second voltage is applied to the primary winding of the transformer, the inductor, and the capacitor, the second rectifying element is conducted and a current flows to the second switch element. For the series resonant converter, the control means for controlling the voltage applying means for applying the first voltage or the second voltage is used to determine whether or not current flows through the first rectifier element and current flows through the second rectifier element. A current detection unit is provided for detecting whether or not a current flows through the first switch element and whether or not a current flows through the second switch element. Then, when the control means detects that the current has flowed to the first rectifying element or the first switch element by the current detection section, the application of the second voltage by the voltage application means is stopped, and the current detection section When it is detected that a current flows through the rectifying element 2 or the second switch element, the application of the first voltage by the voltage applying means is stopped. According to this, the same effect as (1) can be produced.

  (6) In the present invention, a first voltage or a second voltage is applied to the transformer, the inductor and the capacitor connected in series with the primary winding of the transformer, and the primary winding, the inductor, and the capacitor of the transformer. A voltage applying means for applying, a first switch element incorporating a first rectifier element, and a second switch element incorporating a second rectifier element, and comprising a secondary winding of the transformer And a rectifying / smoothing means for rectifying and smoothing the voltage, the control means for controlling the voltage applying means, and whether or not a current flows to the first rectifying element and the second A current detection unit that detects whether a current flows through the rectifying element, whether a current flows through the first switch element, and whether a current flows through the second switch element; When the first voltage is applied to the primary winding of the transformer, the inductor, and the capacitor by controlling the voltage application means, the first rectifier element becomes conductive and the first switch element When the second voltage is applied to the primary winding of the transformer, the inductor, and the capacitor by controlling the voltage application means, the second rectifying element becomes conductive, When a current flows through the second switch element and the current detector detects that a current flows through the first rectifier element or the first switch element, the voltage application unit is controlled to control the voltage of the transformer. The application of the second voltage to the primary winding, the inductor, and the capacitor is stopped, and a current is supplied to the second rectifier element or the second switch element by the current detection unit. When the flow is detected, the voltage application means is controlled to stop the application of the first voltage to the primary winding of the transformer, the inductor, and the capacitor. Has proposed.

  According to this invention, with respect to the series resonant converter of (5), the first rectifying element and the second rectifying element, the first switch element connected in parallel with the first rectifying element, and the second rectifying element Instead of the second switch element connected in parallel with the rectifier element, a first switch element incorporating the first rectifier element and a second switch element incorporating the second rectifier element are provided. It was. According to this, the same effect as (5) can be produced.

  (7) The present invention relates to the control means of the series resonant converter according to (5) or (6), wherein the current detection unit includes a voltage across the first rectifier element and a voltage across the second rectifier element. Or a voltage detection unit that detects a voltage of an input terminal and an output terminal of the first switch element and a voltage of an input terminal and an output terminal of the second switch element. A control means for the converter is proposed.

  According to this invention, the current detection unit includes the voltage across the first rectifier element and the voltage across the second rectifier element, or the voltage across the input terminal and the output terminal of the first switch element and the second voltage. A voltage detector for detecting the voltage at the input terminal and the output terminal of the switch element is provided.

  Here, when a current flows through the first rectifier element or the first switch element, the voltages at both ends of the first rectifier element and the voltages at the input terminal and the output terminal of the first switch element are set to predetermined values. Become. Further, when a current flows through the second rectifier element and the second switch element, the voltage at both ends of the second rectifier element and the voltage at the input terminal and the output terminal of the second switch element are set to predetermined values. For this reason, the voltage detection unit causes the voltage at both ends of the first rectifier element and the voltage at both ends of the second rectifier element, or the voltage at the input terminal and the output terminal of the first switch element, and the voltage of the second switch element. By detecting the voltage at the input terminal and the output terminal, whether or not a current flows through the first rectifier element or the first switch element, and whether a current flows through the second rectifier element or the second switch element Whether or not can be detected.

  (8) According to the present invention, in the control means of the series resonant converter according to any one of (5) to (7), a current flows to the first rectifier element or the first switch element by the current detection unit. And when the application of the second voltage to the primary winding of the transformer, the inductor, and the capacitor is stopped by controlling the voltage application means, the voltage application means is controlled to A first period during which the first voltage is applied to the primary winding, the inductor, and the capacitor is set to be the same as a period during which the second voltage is applied, and the current detection unit causes the first period to be applied. 2 and detecting the current flowing in the second rectifier element or the second switch element, and controlling the voltage application means to control the first current to the primary winding of the transformer, the inductor, and the capacitor. When the voltage application is stopped, the voltage application means is controlled to apply the first voltage during a second period in which the second voltage is applied to the primary winding of the transformer, the inductor, and the capacitor. 8. The control means for a series resonant converter according to claim 5, wherein the control means is set to be the same as the period of time.

  According to the present invention, the current detector detects that the current has flown through the first rectifier element or the first switch element, and controls the voltage application means to control the primary winding, the inductor, and the capacitor of the transformer. When the application of the second voltage is stopped, the voltage application means is controlled to apply the first voltage to the primary winding, inductor and capacitor of the transformer, and the period during which the second voltage is applied It was decided to set to be the same. Further, the current detection unit detects that a current has flowed to the second rectifier element or the second switch element, and controls the voltage application means to adjust the first voltage to the primary winding, inductor, and capacitor of the transformer. When the application is stopped, the second period in which the voltage application means is controlled to apply the second voltage to the primary winding, inductor, and capacitor of the transformer is the same as the period during which the first voltage was applied. It was set as the characteristic. According to this, the same effect as (4) can be produced.

  (9) The present invention provides the control means for the series resonant converter according to any one of (1) to (8), wherein the inductor is provided using a leakage inductance of the transformer. Proposed means.

  According to this invention, the inductor is provided using the leakage inductance of the transformer. According to this, an effect similar to the effect mentioned above can be produced.

  (10) The present invention includes a transformer, a first inductor and a capacitor connected in series with the primary winding of the transformer, a second inductor connected in parallel with the primary winding of the transformer, and the transformer Voltage applying means for applying a first voltage or a second voltage to the primary winding, the first inductor, the second inductor, and the capacitor, and a first rectifier element and a second one that are alternately conducted A rectifying and smoothing means configured to include a rectifying element and rectify and smooth the voltage of the secondary winding of the transformer, and a control means for controlling the voltage applying means, A current detection unit configured to detect whether a current flows through the first rectifier element and whether a current flows through the second rectifier element; and controls the voltage application unit to control the primary winding of the transformer When the first voltage is applied to the first inductor, the second inductor, and the capacitor, the first rectifier element is turned on, and the voltage application means is controlled to control 1 of the transformer. When the second voltage is applied to the secondary winding, the first inductor, the second inductor, and the capacitor, the second rectifier element is turned on, and the current detector detects the first When it is detected that a current flows through the rectifying element, the voltage application means is controlled to apply the second voltage to the primary winding of the transformer, the first inductor, the second inductor, and the capacitor. When the current detection unit detects that a current has flowed to the second rectifier element, the voltage application means is controlled to control the primary winding of the transformer, the first inductor, and the second of It proposes the control means of the series resonant converter characterized by stopping application of the first voltage and inductor for said capacitor.

  According to this invention, the inductor provided in the series resonance converter of (1) is used as the first inductor, and the second inductor connected in parallel with the primary winding of the transformer is newly provided. According to this, the same effect as (1) can be produced.

  (11) The present invention provides the control means for the series resonant converter according to (10), wherein the current detection unit calculates a voltage across the first rectifier element and a voltage across the second rectifier element. The control means of the series resonance converter characterized by providing the voltage detection part to detect is proposed.

  According to this invention, the voltage detector for detecting the voltage across the first rectifier element and the voltage across the second rectifier element is provided in the current detector. According to this, the same effect as (3) can be produced.

  (12) In the control unit of the series resonance converter according to (10) or (11), the present invention detects that a current has flowed to the first rectifying element by the current detection unit, and controls the voltage application unit. When the application of the second voltage to the primary winding of the transformer, the first inductor, the second inductor, and the capacitor is stopped, the voltage applying means is controlled to control the 1 of the transformer. A first period during which the first voltage is applied to the next winding, the first inductor, the second inductor, and the capacitor is set to be the same as a period during which the second voltage is applied. The current detector detects that a current has flown through the second rectifying element, and controls the voltage application means to control the primary winding of the transformer, the first inductor, and the second inductor; Said key When the application of the first voltage to the capacitor is stopped, the voltage application means is controlled to apply the second voltage to the primary winding, the first inductor, the second inductor, and the capacitor of the transformer. A control means for a series resonant converter is proposed in which the second period during which the voltage is applied is set to be the same as the period during which the first voltage is applied.

  According to the present invention, the current detector detects that a current has flown through the first rectifier element, and controls the voltage application means to control the primary winding of the transformer, the first inductor, the second inductor, and the capacitor. When the application of the second voltage is stopped, the voltage application means is controlled to apply a first period in which the first voltage is applied to the primary winding of the transformer, the first inductor, the second inductor, and the capacitor. Therefore, the period is set to be the same as the period during which the second voltage is applied. Further, the current detection unit detects that a current has flown through the second rectifier element, and controls the voltage application means to control the first to the transformer primary winding, the first inductor, the second inductor, and the capacitor. When the application of the voltage is stopped, a second period in which the second voltage is applied to the primary winding of the transformer, the first inductor, the second inductor, and the capacitor by controlling the voltage application means is designated as the first voltage. The period was set to be the same as that applied. According to this, the same effect as (4) can be produced.

  (13) The present invention provides the control means for the series resonant converter according to any one of (10) to (12), wherein the first inductor is provided using a leakage inductance of the transformer. A control means for the converter is proposed.

  According to the present invention, the first inductor is provided using the leakage inductance of the transformer. According to this, an effect similar to the effect mentioned above can be produced.

  (14) The present invention provides the control means for the series resonant converter according to any one of (4), (8), and (12), wherein the first period is started until a predetermined time elapses. A control means for a series resonant converter is proposed in which a predetermined dead period is provided after a lapse of a predetermined time from the start of two periods.

  According to the present invention, the predetermined dead period is provided until a predetermined time elapses after the first period starts and until a predetermined time elapses after the second period starts.

  Here, in the period from the start of the first period to the elapse of the predetermined time, or the period from the start of the second period to the elapse of the predetermined time, even though no resonance has occurred. In some cases, a current flows through one of the first rectifying element and the second rectifying element that does not flow during steady operation. In this case, it is erroneously determined that the resonance is lost. Therefore, since the predetermined dead period is provided, the period from the end of the first period to the end of the predetermined dead period or the period from the end of the second period to the end of the predetermined dead period. Even if a current flows through one of the first rectifying element and the second rectifying element that does not flow during steady operation, it can be prevented that it is erroneously determined that a resonance loss occurs.

  According to the present invention, loss of resonance in a series resonant converter can be prevented.

1 is a circuit diagram of a series resonant converter according to a first embodiment of the present invention. It is a flowchart of the said series resonance converter. It is a flowchart of the said series resonance converter. It is a timing chart of the series resonance converter at the time of steady operation. It is a timing chart of the series resonance converter at the time of resonance loss protection operation. It is a circuit diagram of the series resonance converter which concerns on 2nd Embodiment of this invention. It is a circuit diagram of the series resonance converter which concerns on 3rd Embodiment of this invention. It is a circuit diagram of the series resonance converter which concerns on 4th Embodiment of this invention. It is a circuit diagram of the series resonance converter which concerns on 5th Embodiment of this invention. It is a circuit diagram of the series resonance converter which concerns on 6th Embodiment of this invention. It is a circuit diagram of the series resonance converter which concerns on 7th Embodiment of this invention. It is a circuit diagram of the series resonance converter which concerns on 8th Embodiment of this invention. It is a circuit diagram of the series resonant converter which concerns on 9th Embodiment of this invention. It is a circuit diagram of the series resonance converter which concerns on a prior art example.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the constituent elements in the following embodiments can be appropriately replaced with existing constituent elements and the like, and various variations including combinations with other existing constituent elements are possible. Accordingly, the description of the following embodiments does not limit the contents of the invention described in the claims.

<First Embodiment>
FIG. 1 is a circuit diagram of a series resonant converter 1 according to the first embodiment of the present invention. The series resonant converter 1 is different from the series resonant converter 100 according to the conventional example shown in FIG. 14 in that the anode of the diode D1 and the output terminal OUT2 are connected via the first current detection unit 21, and the anode of the diode D2. And the output terminal OUT2 are connected to each other through the second current detection unit 22. In the series resonant converter 1, the same constituent elements as those of the series resonant converter 100 are denoted by the same reference numerals, and the description thereof is omitted.

  The first current detector 21 detects a current flowing from the output terminal OUT2 toward the anode of the diode D1, that is, a current flowing from the anode of the diode D1 to the cathode. The second current detector 22 detects a current flowing from the output terminal OUT2 toward the anode of the diode D2, that is, a current flowing from the anode of the diode D2 to the cathode. The detection results by the first current detection unit 21 and the second current detection unit 22 are transmitted to the second control unit 131, and the second control unit 131 outputs a drive signal corresponding to the transmitted detection results to the first control unit 131. 1 to the control unit 111.

  Operations of the series resonant converter 1 including the first current detection unit 21 and the second current detection unit 22 will be described with reference to FIGS. 2 and 3 are flowcharts of the series resonant converter 1. FIG. 4 is a timing chart of the series resonance converter 1 during steady operation, and FIG. 5 is a timing chart of the series resonance converter 1 during resonance loss protection operation.

  First, the operation of the series resonant converter 1 will be described with reference to FIGS. 2 and 3.

  In step S1, the second control unit 131 transmits a drive signal for turning on the switch element Q1 to the first control unit 111, and the process proceeds to step S2. According to this process, the first control unit 111 supplies a control signal to the gates of the switch elements Q1 and Q2, thereby turning on the switch element Q1 and turning off the switch element Q2.

  In step S2, the second controller 131 starts measuring the time during which the switch element Q1 is in the on state, and proceeds to step S3.

  In step S3, the second control unit 131 determines whether or not the predetermined dead period has ended. If it is determined that the predetermined dead period has ended, the process proceeds to step S4. If it is determined that the predetermined dead period has not ended, step S3 is repeated.

  In step S <b> 4, the second control unit 131 determines whether or not a current flows through the diode D <b> 2 based on the detection result by the second current detection unit 22. If it is determined that current flows from the anode of the diode D2 to the cathode, the process proceeds to step S6. If it is determined that current does not flow from the anode of the diode D2 to the cathode, the process proceeds to step S5.

  In step S5, the second control unit 131 determines whether or not the time during which the switch element Q1 that has started measurement in step S2 is in the ON state has become half of the switching cycle. If it is determined that the above-described time has become half of the switching period, the process proceeds to step S6. If it is determined that the above-described time has not become half the switching period, the process proceeds to step S4.

  In step S6, the second control unit 131 finishes measuring the time when the switch element Q1 started in step S2 is in the on state, and proceeds to step S7.

  In step S7, the second control unit 131 transmits a drive signal for turning off the switch element Q1 to the first control unit 111, and the process proceeds to step S8. According to this processing, the first control unit 111 supplies a control signal to the gates of the switch elements Q1 and Q2, thereby turning off the switch element Q1 and turning off the switch element Q2.

  In step S8, the second control unit 131 sets the switching cycle to twice the time during which the switch element Q1 that has finished the measurement in step S6 is in the ON state, and proceeds to step S9.

  In step S9, the second control unit 131 transmits a drive signal for turning on the switch element Q2 to the first control unit 111, and the process proceeds to step S10. According to this process, the first control unit 111 supplies a control signal to the gates of the switch elements Q1 and Q2, thereby turning off the switch element Q1 and turning on the switch element Q2.

  In step S10, the second control unit 131 starts measuring the time during which the switch element Q2 is in the ON state, and proceeds to step S11.

  In step S11, the second control unit 131 determines whether or not the predetermined dead period has ended. If it is determined that the predetermined dead period has ended, the process proceeds to step S12. If it is determined that the predetermined dead period has not ended, step S11 is repeated.

  In step S <b> 12, the second control unit 131 determines whether or not a current flows through the diode D <b> 1 based on the detection result by the first current detection unit 21. If it is determined that current flows from the anode of the diode D1 to the cathode, the process proceeds to step S14. If it is determined that current does not flow from the anode of the diode D1 to the cathode, the process proceeds to step S13.

  In step S13, the second control unit 131 determines whether or not the time during which the switch element Q2 that has started measurement in step S10 is in the ON state has become half of the switching cycle. If it is determined that the above-mentioned time has become half of the switching period, the process proceeds to step S14. If it is determined that the above-described time has not become half the switching period, the process proceeds to step S12.

  In step S14, the second control unit 131 finishes measuring the time when the switch element Q2 started in step S10 is in the on state, and proceeds to step S15.

  In step S15, the second control unit 131 transmits a drive signal for turning off the switch element Q2 to the first control unit 111, and the process proceeds to step S16. According to this processing, the first control unit 111 supplies a control signal to the gates of the switch elements Q1 and Q2, thereby turning off the switch element Q1 and turning off the switch element Q2.

  In step S16, similarly to step S8 described above, the second control unit 131 sets the switching period to twice the time during which the switch element Q1 that has finished the measurement in step S14 is in the ON state, and then proceeds to step S1. Move.

  Next, the operation of the series resonant converter 1 during steady operation will be described with reference to FIG.

  At the time of steady operation, the second controller 131 determines that the switching element Q1 is in the ON state in step S5 before determining that the current has flowed from the anode to the cathode of the diode D2 in step S4 in FIG. Before determining that the current has flowed from the anode of the diode D1 to the cathode in step S12 of FIG. 3 in step S12 in FIG. 3, it is assumed that the time during which the switching element Q2 is in the ON state has become half of the switching cycle in step S13. Determine.

Here, I _DQ1 indicates the drain current of the switch element Q1, and I _DQ2 indicates the drain current of the switch element Q2. _ID1 indicates a current flowing from the anode of the diode D1 to the cathode, and _ID2 indicates a current flowing from the anode of the diode D2 to the cathode. V _GQ1 the gate of the switching element Q1 - shows the source _{voltage, V GQ2} the gate of the switching element Q2 - indicates a source voltage.

Further, in the immediately preceding time t1, the gate of the switching element Q1 - the source voltage _{V GQ1,} the gate of the switching element Q2 - the source voltage _{V GQ2,} and VGL, switching elements Q1, Q2 is turned off.

At time t1, the second control unit 131 transmits a drive signal for turning on the switch element Q1 to the first control unit 111. Then, the first control unit 111 sets the gate-source voltage V _GQ1 of the switch element Q1 to VGH. For this reason, the switch element Q2 remains off, but the switch element Q1 is turned on.

When the switch element Q1 is turned on, the drain current I _DQ1 of the switch element Q1 increases as time passes and becomes I ₁ , then decreases as time passes, and becomes I _{2 at} time t2. The drain current _IDQ1 of the switch element Q1 flows from the other end of the primary winding T1 of the transformer T to one end. On the other hand, since the switch element Q2 remains off, the drain current _IDQ2 of the switch element Q2 remains “0”.

Further, when a current flows from the other end of the primary winding T1 of the transformer T to one end, a current I _D1 flows from the anode to the cathode of the diode D1 in accordance with this current, that is, the drain current I _DQ1 of the switch element Q1. The current I _D1 flowing from the anode to the cathode of the diode D1 increases as time passes to become I _4, and then decreases as time passes. On the other hand, the current _ID2 flowing from the anode to the cathode of the diode D2 remains “0”.

At time t2, the second control unit 131 transmits a drive signal for turning off the switch element Q1 to the first control unit 111. Then, the first controller 111 sets the gate-source voltage V _GQ1 of the switch element Q1 to VGL. For this reason, the switch element Q2 remains off, but the switch element Q1 is also off.

When the switch element Q1 is turned off, the drain current _IDQ1 of the switch element Q1 becomes “0”. On the other hand, when the switch element Q1 is turned off, the primary winding T1 of the transformer T tries to continue to flow current from the other end to one end. As a result, the drain current _IDQ2 of the switch element Q1 is negative. after becoming a I ₃ is a value, is close to "0" in accordance with the lapse of time, at time t3 becomes "0". Along with this, the current flowing from the other end of the primary winding T1 of the transformer T to one end decreases as time passes.

When the current flowing from the other end to the one end of the primary winding T1 of the transformer T decreases as time passes, the current _ID1 flowing from the anode to the cathode of the diode _D1 also decreases as time passes, and at time t3 “0”. On the other hand, the current _ID2 flowing from the anode to the cathode of the diode D2 remains “0”.

At time t3 after a predetermined time has elapsed from time t2, the second control unit 131 transmits a drive signal for turning on the switching element Q2 to the first control unit 111. Then, the first control unit 111 sets the gate-source voltage V _GQ2 of the switch element Q2 to VGH. For this reason, the switch element Q1 remains in the off state, but the switch element Q2 is in the on state. In FIG. 4, the timing when the current I _D1 flowing from the anode to the cathode of the diode D1 becomes “0” coincides with the time t3. However, even when the time t3 is earlier than this timing, Since a dead period is provided, it is not erroneously determined as an operation out of resonance.

When the switch element Q2 is turned on, the drain current I _DQ2 switching element Q2, after a I ₁ increases in accordance with the lapse of time, and decreases as time passes, the I ₂ at time t4. The drain current _IDQ2 of the switch element Q2 flows from one end of the primary winding T1 of the transformer T to the other end. On the other hand, since the switch element Q1 remains off, the drain current _IDQ1 of the switch element Q1 remains “0”.

Further, when a current flows from one end to the other end of the primary winding T1 of the transformer T, a current _ID2 flows from the anode to the cathode of the diode D2 in accordance with this current, that is, the drain current _IDQ2 of the switch element Q2. Current I _D2 flowing from the anode of the diode D2 to the cathode, after becoming a I ₄ increases according to the lapse of time, it decreases with the passage of time. On the other hand, the current I _D1 flowing from the anode to the cathode of the diode D1 remains “0”.

At time t4, the second control unit 131 transmits a drive signal for turning off the switching element Q2 to the first control unit 111. Then, the first control unit 111 sets the gate-source voltage V _GQ2 of the switch element Q2 to VGL. For this reason, the switch element Q1 remains in the off state, but the switch element Q2 is also in the off state.

When the switch element Q2 is turned off, the drain current _IDQ2 of the switch element Q2 becomes “0”. On the other hand, when the switch element Q2 is turned off, the primary winding T1 of the transformer T tries to keep current flowing from one end to the other end. As a result, the drain current I _DQ1 of the switch element Q1 is negative. after becoming a I ₃ is a value, is close to "0" in accordance with the lapse of time, the time t5 becomes "0". Accordingly, the current flowing from one end of the primary winding T1 of the transformer T to the other end decreases as time passes.

When the current flowing from one end to the other end of the primary winding T1 of the transformer T decreases as time passes, the current _ID2 flowing from the anode to the cathode of the diode _D2 also decreases as time passes, and at time t5 “0”. On the other hand, the current I _D1 flowing from the anode to the cathode of the diode D1 remains “0”.

At time t5 after a predetermined time has elapsed from time t4, the second control unit 131 transmits a drive signal for turning on the switching element Q1 to the first control unit 111 at time t5, similar to the above-described time t1. . Then, the first control unit 111 sets the gate-source voltage V _GQ1 of the switch element Q1 to VGH. For this reason, the switch element Q2 remains off, but the switch element Q1 is turned on. In FIG. 4, the timing when the current I _D2 flowing from the anode to the cathode of the diode D2 becomes “0” coincides with the time t5. However, even when the time t5 is earlier than this timing, Since a dead period is provided, it is not erroneously determined as an operation out of resonance.

At each of the times t5 to t9, the times t9 to t13, and the times t13 to t17, similarly to the times t1 to t5, the second control unit 131 transmits a drive signal to the first control unit 111, and the switch element a source voltage _{V GQ1,} the gate of the switching element Q2 - - Q1 of the gate to control, and voltage _{V GQ2-source.}

  Next, with reference to FIG. 5, the operation of the series resonant converter 1 during the resonance loss protection operation will be described.

  Here, when the resonance is lost, the current starts to flow through the diodes D1 and D2 that do not flow during steady operation before the occurrence. The diodes D1 and D2 that do not flow current during steady operation are the diode D2 when the switch element Q1 is in the on state and the diode D1 when the switch element Q2 is in the on state. Therefore, the series resonant converter 1 determines that a resonance loss is likely to occur when a current begins to flow through the diodes D1 and D2 that do not flow during steady operation, and performs a resonance loss protection operation.

  At the time of the anti-resonance protection operation, the second controller 131 determines from the anode of the diode D2 in step S4 before determining that the time during which the switch element Q1 is in the on state in step S5 in FIG. Before determining that the current has flown through the cathode and determining that the time during which the switching element Q2 is ON in step S13 in FIG. 3 has become half of the switching period, in step S12, the current flows from the anode to the cathode of the diode D1. It is determined that it has flowed.

Here, in the immediately preceding time t21, the gate of the switching element Q1 - the source voltage _{V GQ1,} the gate of the switching element Q2 - the source voltage _{V GQ2,} and VGL, switching elements Q1, Q2 is turned off .

At time t <b> 21, the second control unit 131 transmits a drive signal for turning on the switch element Q <b> 1 to the first control unit 111. Then, the first control unit 111 sets the gate-source voltage V _GQ1 of the switch element Q1 to VGH. For this reason, the switch element Q2 remains off, but the switch element Q1 is turned on.

When the switch element Q1 is turned on, the drain current I _DQ1 of the switch element Q1, after a I ₁ increased by following over time, it decreases with the passage of time. The drain current _IDQ1 of the switch element Q1 flows from the other end of the primary winding T1 of the transformer T to one end. On the other hand, since the switch element Q2 remains off, the drain current _IDQ2 of the switch element Q2 remains “0”.

Further, when a current flows from the other end of the primary winding T1 of the transformer T to one end, a current I _D1 flows from the anode to the cathode of the diode D1 in accordance with this current, that is, the drain current I _DQ1 of the switch element Q1. Current I _D1 flowing from the anode of the diode D1 to the cathode, after becoming a I ₄ increases and in accordance with the lapse of time, and decreases as time passes, at time t22 becomes "0". On the other hand, the current _ID2 flowing from the anode to the cathode of the diode D2 remains “0”.

At time t23, the current I _D2 begins to flow from the anode to the cathode of the diodes D1 and D2 that do not flow during steady operation, that is, the diode D2. Then, the second current detection unit 22 detects that the current I _D2 has started to flow from the anode to the cathode of the diode D2, and the second control unit 131 outputs a drive signal for turning the switch element Q1 to the first state. To the control unit 111. As a result, the first control unit 111 sets the gate-source voltage V _GQ1 of the switch element Q1 to VGL. For this reason, the switch element Q2 remains off, but the switch element Q1 is also off. According to this, when the current starts to flow through the diode D2, which does not flow during steady operation, during the period when the switch element Q1 is in the on state, the switch element Q1 is in the off state. Can be prevented.

Further, when the switch element Q1 is turned off, the drain current _IDQ1 of the switch element Q1 becomes “0”. On the other hand, when the switch element Q1 is turned off, the primary winding T1 of the transformer T tries to continue to flow current from the other end to one end, and as a result, the drain current _IDQ2 of the switch element Q2 is negative. after becoming a I ₃₁ is a value, is close to "0" in accordance with the lapse of time, at time t24 becomes "0".

At time t24 after a predetermined time has elapsed from time t23, the second control unit 131 transmits a drive signal for turning on the switching element Q2 to the first control unit 111. Then, the first control unit 111 sets the gate-source voltage V _GQ2 of the switch element Q2 to VGH. For this reason, the switch element Q1 remains in the off state, but the switch element Q2 is in the on state. In FIG. 5, the timing at which the current I _D1 flowing from the anode to the cathode of the diode D1 becomes “0” is earlier than the time t24. However, even when the time t24 is earlier than this timing, a predetermined insensitivity is obtained. Since the period is provided, it is not erroneously determined that the operation is out of resonance.

When the switch element Q2 is turned on, the drain current I _DQ2 switching element Q2, after a I ₁ increased by following over time, it decreases with the passage of time. The drain current _IDQ2 of the switch element Q2 flows from one end of the primary winding T1 of the transformer T to the other end. On the other hand, since the switch element Q1 remains off, the drain current _IDQ1 of the switch element Q1 remains “0”.

Further, when a current flows from one end to the other end of the primary winding T1 of the transformer T, a current _ID2 flows from the anode to the cathode of the diode D2 in accordance with this current, that is, the drain current _IDQ2 of the switch element Q2. The current I _D2 flowing from the anode to the cathode of the diode D2 increases as time elapses and becomes I ₄ , then decreases as time elapses, and becomes “0” at time t25. On the other hand, the current I _D1 flowing from the anode to the cathode of the diode D1 remains “0”.

At time t26, the current I _D1 begins to flow from the anode to the cathode of the diodes D1 and D2 that do not flow during steady operation, that is, the diode D1. Then, the first current detection unit 21 detects that the current I _D1 has started to flow from the anode to the cathode of the diode D1, and the second control unit 131 outputs a drive signal for turning the switch element Q2 to the first state. To the control unit 111. As a result, the first control unit 111 sets the gate-source voltage V _GQ2 of the switch element Q2 to VGL. For this reason, the switch element Q1 remains in the off state, but the switch element Q2 is also in the off state. According to this, when the current starts to flow through the diode D1 in which the current does not flow during the steady operation of the diodes D1 and D2 during the period in which the switch element Q2 is in the on state, the switch element Q2 is in the off state. Can be prevented.

Further, when the switch element Q2 is turned off, the drain current _IDQ1 of the switch element Q2 becomes “0”. On the other hand, when the switch element Q2 is turned off, the primary winding T1 of the transformer T tries to keep current flowing from one end to the other end. As a result, the drain current I _DQ1 of the switch element Q1 is negative. after becoming a I ₃₁ is a value, is close to "0" in accordance with the lapse of time, at time t27 becomes "0".

At time t27 after a predetermined time has elapsed from time t26, the second control unit 131 transmits a drive signal for turning on the switching element Q1 to the first control unit 111 at time t27, similar to the above-described time t21. . Then, the first control unit 111 sets the gate-source voltage V _GQ1 of the switch element Q1 to VGH. For this reason, the switch element Q2 remains off, but the switch element Q1 is turned on. In FIG. 5, the timing when the current _ID2 flowing from the anode to the cathode of the diode D2 becomes “0” is earlier than the time t27. However, even when the time t27 is earlier than this timing, a predetermined insensitivity is obtained. Since the period is provided, it is not erroneously determined that the operation is out of resonance.

At each of time t27 to t33 and time t33 to t39, the drive signal is transmitted to the first control unit 111 by the second control unit 131 in the same manner as at time t21 to t27, and the gate-source of the switch element Q1 and between the voltage _{V GQ1,} the gate of the switching element Q2 - controlling a voltage _{V GQ2-source.}

  According to the above series resonant converter 1, the following effects can be achieved by the first current detection unit 21, the second current detection unit 22, the first control unit 111, and the second control unit 131.

When the first current detection unit 21 detects that the current I _D1 has started to flow from the anode to the cathode of the diode D1, the second control unit 131 performs a first control on a drive signal for turning off the switch element Q2. The switch element Q2 is turned off by the first control unit 111. That is, when the current starts to flow through the diode D1, which does not flow during steady operation, in the period in which the switch element Q2 is on, the switch element Q2 is turned off. Similarly, even when the switch element Q1 is in the ON state, when the current starts to flow through the diode D2, which does not flow during steady operation, of the diodes D1 and D2, the switch element Q1 is turned off. According to the above, loss of resonance can be prevented.

  Conventionally, since it is not known when the resonance loss occurs, the switch elements Q1 and Q2 may be switched from the on state to the off state early to prevent the resonance loss. In this case, the period during which the switch element Q1 is continuously on and the period during which the switch element Q2 is continuously on are shortened, and the DC power source that outputs a low voltage is connected to the input terminal IN1. When connected to IN2, a desired voltage may not be output from the output terminals OUT1 and OUT2. However, the series resonant converter 1 can determine that a resonance loss occurs when the first current detection unit 21 and the second current detection unit 22 cause a current to flow in the diode D1 or the diode D2 in which no current flows during the steady operation. For this reason, it is possible to switch the switching elements Q1 and Q2 from the on state to the off state later, while preventing the loss of resonance. Therefore, as compared with the conventional case, the period during which the switch element Q1 is continuously turned on and the period during which the switch element Q2 is continuously turned on can be lengthened, so that a desired voltage is conventionally applied to the output terminal OUT1. In some cases, a desired voltage can be output from the output terminals OUT1 and OUT2 even if a DC power supply that outputs a voltage that cannot be output from OUT2 is connected to the input terminals IN1 and IN2.

  Conventionally, by connecting an electrolytic capacitor in parallel with the DC power source connected to the input terminals IN1 and IN2, even if no power is supplied from the DC power source, the power stored in the electrolytic capacitor can be used for a certain period of time. In some cases, a desired voltage is output from the output terminals OUT1 and OUT2. In this case, the capacitance of the electrolytic capacitor is set to be large so that a desired voltage can be output only for a certain period even if a high stop voltage is set in order to prevent loss of resonance. However, in the series resonant converter 1, the first current detection unit 21, the second current detection unit 22, the first control unit 111, and the second control unit 131 can prevent loss of resonance. For this reason, compared with the conventional case, by making the capacitance of the electrolytic capacitor the same, a desired voltage can be output from the output terminals OUT1 and OUT2 for a longer time. Alternatively, a desired voltage can be output from the output terminals OUT1 and OUT2 for the same period even if the number of electrolytic capacitors is reduced or the capacitance is reduced as compared with the conventional case. Alternatively, the number of turns of the primary winding T1 of the transformer T is increased or the number of turns of the first secondary winding T2 and the second secondary winding T3 of the transformer T is decreased as compared with the conventional case. However, since a desired voltage can be output from the output terminals OUT1 and OUT2 only during the same period, the effective current value flowing through each element provided in the series resonant converter 1 can be reduced, and high efficiency can be realized.

  Further, the on / off of the switch elements Q1, Q2 is controlled so that the time during which the switch elements Q1, Q2 are in the on state is half of the switching cycle. Therefore, based on the detection results by the first current detection unit 21 and the second current detection unit 22, the switch element Q1 and the switch element Q2 are turned off, and the time during which the switch element Q1 and the switch element Q2 are on is Even when shortened, there is a difference between the period in which the switch element Q1 is on and the switch element Q2 is off and the period in which the switch element Q1 is off and the switch element Q2 is on. Can be prevented. Therefore, it is possible to prevent the partial excitation of the transformer T that occurs due to the difference between these periods.

  In addition, in a short period of time immediately after the switch element Q1 is turned on even though no resonance has occurred, a current flows through the diode D2, which does not flow during steady operation, of the diodes D1 and D2, In a short period immediately after the element Q2 is turned on, a current may flow through the diode D1, which does not flow during steady operation, of the diodes D1 and D2. However, since a predetermined dead period is provided after the switch element Q1 is turned on and after the switch element Q2 is turned on, the diodes D1 and D2 are not out of resonance. Even if a current flows through a current that does not flow during steady operation, it is possible to prevent erroneous determination that a resonance loss occurs. According to this, the following effects can also be achieved.

For example, in FIG. 4, the timing when the current I _D1 flowing from the anode to the cathode of the diode D1 becomes “0” matches the timing when the switch element Q2 is turned on (for example, time t3). . However, even when the timing at which the switching element Q2 is turned on is earlier than the timing at which the current _ID1 flowing from the anode to the cathode of the diode D1 becomes “0”, the switching element Q2 is turned on. If the period from when the current I _D1 flowing from the anode to the cathode of the diode D1 becomes “0” within the predetermined dead period described above, it is possible to prevent erroneous determination that the resonance is lost.

Second Embodiment
FIG. 6 is a circuit diagram of a series resonant converter 1A according to the second embodiment of the present invention. The series resonant converter 1A is different from the series resonant converter 1 according to the first embodiment of the present invention shown in FIG. 1 in that the capacitor C2 is not provided. In the series resonant converter 1A, the same constituent elements as those of the series resonant converter 1 are denoted by the same reference numerals, and the description thereof is omitted.

  According to the above series resonant converter 1 </ b> A, the same effect as the above-described series resonant converter 1 can be obtained.

<Third Embodiment>
FIG. 7 is a circuit diagram of a series resonant converter 1B according to the third embodiment of the present invention. The series resonant converter 1B is different from the series resonant converter 1 according to the first embodiment of the present invention shown in FIG. 1 in that the capacitor C1 is not provided. In the series resonant converter 1B, the same constituent elements as those of the series resonant converter 1 are denoted by the same reference numerals, and the description thereof is omitted.

  According to the above series resonant converter 1 </ b> B, the same effect as the above-described series resonant converter 1 can be obtained.

<Fourth embodiment>
FIG. 8 is a circuit diagram of a series resonant converter 1C according to the fourth embodiment of the present invention. The series resonant converter 1C is different from the series resonant converter 1 according to the first embodiment of the present invention shown in FIG. 1 in that switch elements Q1A and Q1B are provided, and a capacitor C1A is provided instead of the capacitors C1 and C2. Is different. In the series resonant converter 1C, the same constituent elements as those of the series resonant converter 1 are denoted by the same reference numerals, and the description thereof is omitted.

  One end of the inductor L1 is connected to one end of the primary winding T1 of the transformer T. The other end of the inductor L1 is connected to the source of the switch element Q1 and the drain of the switch element Q2 via the capacitor C1A.

  The switch elements Q1A and Q2A are composed of N-channel MOSFETs, and are turned on when the gate-source voltage becomes VGH, and turned off when the gate-source voltage becomes VGL. The input terminal IN1 is connected to the drain of the switch element Q1A, and the first controller 111 is connected to the gate of the switch element Q1A. The input terminal IN2 is connected to the source of the switch element Q2A, and the first controller 111 is connected to the gate of the switch element Q2A. The other end of the primary winding T1 of the transformer T is connected to the source of the switch element Q1A and the drain of the switch element Q2A. These switch elements Q1A and Q2A form a full bridge circuit by the switch elements Q1 and Q2.

  According to the above series resonant converter 1 </ b> C, the same effect as the above-described series resonant converter 1 can be obtained.

<Fifth Embodiment>
FIG. 9 is a circuit diagram of a series resonant converter 1D according to the fifth embodiment of the present invention. The series resonant converter 1D is different from the series resonant converter 1 according to the first embodiment of the present invention shown in FIG. 1 in that it includes diodes D1A and D2A, and the first secondary winding T2 and the second of the transformer T. The difference is that a secondary winding T4 of the transformer T is provided instead of the secondary winding T3. In the series resonant converter 1D, the same constituent elements as those of the series resonant converter 1 are denoted by the same reference numerals, and the description thereof is omitted.

  The anode of the diode D1 and the cathode of the diode D2 are connected to one end of the secondary winding T4 of the transformer T. The anode of the diode D1A and the diode are connected to the other end of the secondary winding T4 of the transformer T. To the cathode of D2A. The output terminal OUT1 and the cathode of the diode D1A are connected to the cathode of the diode D1 via the first current detection unit 21, and the output of the diode D2 is connected to the anode of the diode D2 via the second current detection unit 22. The terminal OUT2 is connected to the anode of the diode D2A.

  According to the above series resonant converter 1D, the same effect as the above-described series resonant converter 1 can be obtained.

<Sixth Embodiment>
FIG. 10 is a circuit diagram of a series resonant converter 1E according to the sixth embodiment of the present invention. The series resonant converter 1E is different from the series resonant converter 1 according to the first embodiment of the present invention shown in FIG. 1 in that inductors L1A and L1B are provided instead of the inductor L1. In the series resonant converter 1E, the same components as those of the series resonant converter 1 are denoted by the same reference numerals, and the description thereof is omitted.

  The input terminal IN1 is connected to one end of the primary winding T1 of the transformer T via the capacitor C1, and the input terminal IN2 is connected to the end of the primary winding T1 of the transformer T.

  One end of the first secondary winding T2 of the transformer T is connected to the cathode of the diode D1 via the inductor L1A, and one end of the second secondary winding T3 of the transformer T is connected via the inductor L1B. The cathode of the diode D2 is connected.

  According to the above series resonant converter 1E, the same effect as the above-described series resonant converter 1 can be obtained.

<Seventh embodiment>
FIG. 11 is a circuit diagram of a series resonant converter 1F according to the seventh embodiment of the present invention. The series resonant converter 1F is different from the series resonant converter 1 according to the first embodiment of the present invention shown in FIG. 1 in that an inductor L2 is provided. In the series resonant converter 1F, the same constituent elements as those of the series resonant converter 1 are denoted by the same reference numerals, and the description thereof is omitted.

  One end of the primary winding T1 of the transformer T is connected to one end of the inductor L1 and one end of the inductor L2. The other end of the primary winding T1 of the transformer T is connected to the source of the switch element Q1, the drain of the switch element Q2, and the other end of the inductor L2.

  According to the above series resonant converter 1F, the same effect as the above-described series resonant converter 1 can be obtained.

<Eighth Embodiment>
FIG. 12 is a circuit diagram of a series resonant converter 1G according to the eighth embodiment of the present invention. The series resonant converter 1G is different from the series resonant converter 1 according to the first embodiment of the present invention shown in FIG. 1 in that it includes switch elements Q3 and Q4, and the operations of the first current detection unit and the second current detection unit. And is different. In the series resonant converter 1G, the same constituent elements as those of the series resonant converter 1 are denoted by the same reference numerals, and the description thereof is omitted.

  Switch elements Q3 and Q4 are formed of N-channel MOSFETs. One end of the first secondary winding T2 of the transformer T and the cathode of the diode D1 are connected to the drain of the switch element Q3, and the output terminal OUT2 and the anode of the diode D1 are connected to the source of the switch element Q3. And the first current detector 21A is connected to the gate of the switch element Q3. One end of the second secondary winding T3 of the transformer T and the cathode of the diode D2 are connected to the drain of the switch element Q4, and the output terminal OUT2 and the anode of the diode D2 are connected to the source of the switch element Q4. And the second current detector 22A is connected to the gate of the switch element Q4.

  The first current detector 21A detects the drain current of the switch element Q3 and supplies a control signal to the gate of the switch element Q3. The detection result of the drain current of the switch element Q3 by the first current detection unit 21A is transmitted to the second control unit 131.

  The second current detector 22A detects the drain current of the switch element Q4 and supplies a control signal to the gate of the switch element Q4. The detection result of the drain current of the switch element Q4 by the second current detection unit 22A is transmitted to the second control unit 131.

  The second control unit 131 transmits a drive signal corresponding to the detection result transmitted from the first current detection unit 21A and the second current detection unit 22A to the first control unit 111.

  According to the above series resonant converter 1G, the same effect as the above-described series resonant converter 1 can be obtained.

<Ninth Embodiment>
FIG. 13 is a circuit diagram of a series resonant converter 1H according to the ninth embodiment of the present invention. The series resonant converter 1H differs from the series resonant converter 1G according to the eighth embodiment of the present invention shown in FIG. 12 in the direction of the switch elements Q3 and Q4 and the direction of the diodes D1 and D2. In the series resonant converter 1H, the same components as those of the series resonant converter 1G are denoted by the same reference numerals, and the description thereof is omitted.

  One end of the first secondary winding T2 of the transformer T and the anode of the diode D1 are connected to the source of the switch element Q3, and the output terminal OUT2 and the cathode of the diode D1 are connected to the drain of the switch element Q3. And are connected. One end of the second secondary winding T3 of the transformer T and the anode of the diode D2 are connected to the source of the switch element Q4, and the output terminal OUT2 and the cathode of the diode D2 are connected to the drain of the switch element Q4. And are connected.

  According to the above series resonant converter 1H, the same effects as those of the above-described series resonant converter 1G can be obtained.

  The present invention is not limited to the above-described embodiment, and various modifications and applications can be made without departing from the gist of the present invention.

  For example, in the series resonant converter 1G according to the above-described eighth embodiment and the series resonant converter 1H according to the above-described ninth embodiment, the drain current of the switch element Q3 is detected by the first current detection unit 21A, and the second Although the drain current of the switch element Q4 is detected by the current detector 22A, the present invention is not limited to this.

  For example, when the drain current of the switch element Q3 flows, the current also flows through the diode D1, and when the drain current of the switch element Q4 flows, the current also flows through the diode D2. Therefore, the current flowing from the anode of the diode D1 to the cathode may be detected by the first current detector 21A, and the current flowing from the anode of the diode D2 to the cathode may be detected by the second current detector 22A.

  When the drain current of the switch element Q3 flows, the switch element Q3 is in an on state, and the potential difference between the drain and the source of the switch element Q3 becomes a predetermined value, and the drain current of the switch element Q4 flows. The switch element Q4 is in an ON state, and the potential difference between the drain and source of the switch element Q4 becomes a predetermined value. For this reason, the potential difference between the drain and source of the switch element Q3 may be detected by the first current detector 21A, and the potential difference between the drain and source of the switch element Q4 may be detected by the second current detector 22A.

  In the series resonant converter 1G according to the above-described eighth embodiment and the series resonant converter 1H according to the above-described ninth embodiment, diodes D1 and D2 are configured by the body diodes of the switch elements Q3 and Q4. Also good.

  The present invention can be applied to a control unit of a series resonant converter used in a switching power supply device or the like.

1, 1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H, 100; series resonant converters 21, 21A; first current detection units 22, 22A; second current detection unit 111; first control unit 131; Second controllers C1, C2, C3; capacitors D1, D2, D1A, D2A; diodes L1, L1A, L1B, L2; inductors Q1, Q2, Q1A, Q2A, Q3, Q4; switch element T;

Claims (14)

With a transformer,
An inductor and a capacitor connected in series with the primary winding of the transformer;
Voltage applying means for applying a first voltage or a second voltage to the primary winding of the transformer, the inductor, and the capacitor;
Rectifying and smoothing means configured to include first rectifying elements and second rectifying elements that are alternately conducted to rectify and smooth the voltage of the secondary winding of the transformer;
In a series resonant converter comprising: a control means for controlling the voltage application means,
A current detection unit that detects whether or not a current flows through the first rectifying element and whether or not a current flows through the second rectifying element;
When the first voltage is applied to the transformer primary winding, the inductor, and the capacitor by controlling the voltage application means, the first rectifying element is conductive,
When the second voltage is applied to the primary winding of the transformer, the inductor, and the capacitor by controlling the voltage application means, the second rectifier element is conducted,
When the current detection unit detects that a current flows through the first rectifier element, the voltage application unit is controlled to apply the second voltage to the primary winding of the transformer, the inductor, and the capacitor. Stop
When the current detection unit detects that a current has flowed to the second rectifier element, the voltage application unit is controlled to apply the first voltage to the primary winding of the transformer, the inductor, and the capacitor. A control means for a series resonant converter, characterized in that With a transformer,
A capacitor connected in series with the primary winding of the transformer;
An inductor connected in series with the secondary winding of the transformer;
Voltage applying means for applying a first voltage or a second voltage to the primary winding of the transformer, the inductor, and the capacitor;
Rectifying and smoothing means configured to include first rectifying elements and second rectifying elements that are alternately conducted to rectify and smooth the voltage of the secondary winding of the transformer;
In a series resonant converter comprising: a control means for controlling the voltage application means,
A current detection unit that detects whether or not a current flows through the first rectifying element and whether or not a current flows through the second rectifying element;
When the first voltage is applied to the transformer primary winding, the inductor, and the capacitor by controlling the voltage application means, the first rectifying element is conductive,
When the second voltage is applied to the primary winding of the transformer, the inductor, and the capacitor by controlling the voltage application means, the second rectifier element is conducted,
When the current detection unit detects that a current flows through the first rectifier element, the voltage application unit is controlled to apply the second voltage to the primary winding of the transformer, the inductor, and the capacitor. Stop
When the current detection unit detects that a current has flowed to the second rectifier element, the voltage application unit is controlled to apply the first voltage to the primary winding of the transformer, the inductor, and the capacitor. A control means for a series resonant converter, characterized in that   The said current detection part is provided with the voltage detection part which detects the voltage of the both ends of a said 1st rectification element, and the voltage of the both ends of a said 2nd rectification element, It is characterized by the above-mentioned. Means for controlling the series resonant converter. Application of the second voltage to the primary winding of the transformer, the inductor, and the capacitor by controlling the voltage application means by detecting that the current has flowed to the first rectifying element by the current detection unit. The second voltage is applied during a first period in which the voltage application means is controlled to apply the first voltage to the primary winding of the transformer, the inductor, and the capacitor. Set to be the same as the period,
Application of the first voltage to the primary winding of the transformer, the inductor, and the capacitor by controlling the voltage application means by detecting that the current has flowed to the second rectifying element by the current detection unit. The first voltage was applied during a second period in which the voltage application means was controlled to apply the second voltage to the primary winding of the transformer, the inductor, and the capacitor. 4. The series resonance converter control means according to claim 1, wherein the control means is set to be equal to the period. With a transformer,
An inductor and a capacitor connected in series with the primary winding of the transformer;
Voltage applying means for applying a first voltage or a second voltage to the primary winding of the transformer, the inductor, and the capacitor;
First rectifier element and second rectifier element which are alternately conducted, a first switch element connected in parallel with the first rectifier element, and a second switch connected in parallel with the second rectifier element Rectifying and smoothing means configured to rectify and smooth the voltage of the secondary winding of the transformer,
In a series resonant converter comprising: a control means for controlling the voltage application means,
Whether a current flows through the first rectifier element, whether a current flows through the second rectifier element, or whether a current flows through the first switch element, and a current through the second switch element. Including a current detection unit that detects whether or not
When the first voltage is applied to the primary winding of the transformer, the inductor, and the capacitor by controlling the voltage application means, the first rectifier element becomes conductive and the first switch Current flows through the element,
When the second voltage is applied to the transformer primary winding, the inductor, and the capacitor by controlling the voltage application means, the second rectifier element is turned on and the second switch Current flows through the element,
When the current detection unit detects that a current flows through the first rectifier element or the first switch element, the voltage application unit is controlled to control the primary winding of the transformer, the inductor, and the capacitor. Stopping the application of the second voltage to
When the current detection unit detects that a current flows through the second rectifier element or the second switch element, the voltage application unit is controlled to control the primary winding of the transformer, the inductor, and the capacitor. The series resonance converter control means characterized in that the application of the first voltage to is stopped. With a transformer,
An inductor and a capacitor connected in series with the primary winding of the transformer;
Voltage applying means for applying a first voltage or a second voltage to the primary winding of the transformer, the inductor, and the capacitor;
A first switch element including a first rectifier element and a second switch element including a second rectifier element are configured to rectify and smooth the voltage of the secondary winding of the transformer. Rectifying and smoothing means;
In a series resonant converter comprising: a control means for controlling the voltage application means,
Whether a current flows through the first rectifier element, whether a current flows through the second rectifier element, or whether a current flows through the first switch element, and a current through the second switch element. Including a current detection unit that detects whether or not
When the first voltage is applied to the primary winding of the transformer, the inductor, and the capacitor by controlling the voltage application means, the first rectifier element becomes conductive and the first switch Current flows through the element,
When the second voltage is applied to the transformer primary winding, the inductor, and the capacitor by controlling the voltage application means, the second rectifier element is turned on and the second switch Current flows through the element,
When the current detection unit detects that a current flows through the first rectifier element or the first switch element, the voltage application unit is controlled to control the primary winding of the transformer, the inductor, and the capacitor. Stopping the application of the second voltage to
When the current detection unit detects that a current flows through the second rectifier element or the second switch element, the voltage application unit is controlled to control the primary winding of the transformer, the inductor, and the capacitor. The series resonance converter control means characterized in that the application of the first voltage to is stopped.   The current detection unit includes a voltage across the first rectifier element and a voltage across the second rectifier element, or a voltage across the input terminal and the output terminal of the first switch element, and the second 7. The control means for a series resonant converter according to claim 5, further comprising a voltage detection unit that detects a voltage of an input terminal and an output terminal of the switch element. The current detection unit detects that a current has flowed to the first rectifier element or the first switch element, and controls the voltage application unit to control the primary winding of the transformer, the inductor, and the capacitor, A first period in which the first voltage is applied to the primary winding of the transformer, the inductor, and the capacitor by controlling the voltage application means when the application of the second voltage to is stopped. Set to be the same as the period during which two voltages were applied,
The current detection unit detects that a current has flowed to the second rectifier element or the second switch element, and controls the voltage application means to control the primary winding of the transformer, the inductor, and the capacitor, A second period in which the second voltage is applied to the primary winding of the transformer, the inductor, and the capacitor by controlling the voltage application means when the application of the first voltage to is stopped. 8. The control means for a series resonant converter according to claim 5, wherein the control means is set to be the same as a period during which one voltage is applied.   9. The series resonance converter control means according to claim 1, wherein the inductor is provided by using a leakage inductance of the transformer. With a transformer,
A first inductor and a capacitor connected in series with the primary winding of the transformer;
A second inductor connected in parallel with the primary winding of the transformer;
Voltage applying means for applying a first voltage or a second voltage to the primary winding of the transformer, the first inductor, the second inductor, and the capacitor;
Rectifying and smoothing means configured to include first rectifying elements and second rectifying elements that are alternately conducted to rectify and smooth the voltage of the secondary winding of the transformer;
In a series resonant converter comprising: a control means for controlling the voltage application means,
A current detection unit that detects whether or not a current flows through the first rectifying element and whether or not a current flows through the second rectifying element;
When the voltage application means is controlled to apply the first voltage to the primary winding of the transformer, the first inductor, the second inductor, and the capacitor, the first rectifier element Conducting,
When the second voltage is applied to the primary winding of the transformer, the first inductor, the second inductor, and the capacitor by controlling the voltage application means, the second rectifying element is Conducting,
When the current detection unit detects that a current flows through the first rectifier element, the voltage application unit is controlled to control the primary winding of the transformer, the first inductor, the second inductor, and the Stopping application of the second voltage to the capacitor;
When the current detection unit detects that a current flows through the second rectifier element, the voltage application unit is controlled to control the primary winding of the transformer, the first inductor, the second inductor, and the A control means for a series resonant converter, wherein application of the first voltage to a capacitor is stopped.   11. The series according to claim 10, wherein the current detection unit includes a voltage detection unit that detects a voltage at both ends of the first rectifier element and a voltage at both ends of the second rectifier element. Resonant converter control means. The current detection unit detects that a current has flowed to the first rectifying element, and controls the voltage applying unit to control the primary winding of the transformer, the first inductor, the second inductor, and the When the application of the second voltage to the capacitor is stopped, the voltage application means is controlled to control the first winding, the first inductor, the second inductor, and the capacitor to the first winding of the transformer. The first period for applying the voltage is set to be the same as the period for applying the second voltage,
The current detection unit detects that a current has flowed to the second rectifier element, and controls the voltage application unit to control the primary winding of the transformer, the first inductor, the second inductor, and the When the application of the first voltage to the capacitor is stopped, the voltage application means is controlled to apply the second voltage to the primary winding of the transformer, the first inductor, the second inductor, and the capacitor. 12. The control means for a series resonant converter according to claim 10, wherein the second period during which the voltage is applied is set to be the same as the period during which the first voltage is applied.   13. The series resonance converter control means according to claim 10, wherein the first inductor is provided by using a leakage inductance of the transformer.   5. A predetermined dead period is provided until a predetermined time elapses after starting the first period and until a predetermined time elapses after starting the second period. The control means of the series resonant converter in any one of 8 or 12.

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