JP6469493B2 - Voltage converter and control method of voltage converter - Google Patents

Description

  The present invention relates to a power conversion device that converts an input voltage into a predetermined output voltage, such as a DCDC converter, and a control method for the power conversion device.

  2. Description of the Related Art A switching type power conversion device that drives a switching element to generate an induced voltage in an inductor and thereby outputs a voltage of a battery that is boosted or lowered is generally used. For example, when an engine is restarted from an idling stop of an automobile, a DCDC converter that drives a switching element with a driving voltage of pulse width modulation (PWM) is used to compensate for a voltage drop of the battery. In such a DCDC converter, when the engine is restarted, the duty ratio is increased in order to increase the battery voltage quickly. However, when the battery voltage recovers and approaches a steady state, the duty ratio is decreased and a small voltage boost is performed. Is required.

  When the minimum duty ratio that can be set when the drive voltage is controlled by PWM, that is, the minimum pulse width is limited, for example, Patent Document 1 describes changing to the operation mode pulse skip mode of the DCDC converter. Yes.

JP 2014-57469 A

  As described in Patent Document 1 described above, when a minute boosting operation is performed in the pulse skip mode, the pulse period is lengthened without changing the pulse width, that is, the boosting by one pulse is increased. There is a problem that the generated ripple increases.

  An object of the present invention has been made in view of the above-described problems. For example, a voltage conversion device capable of outputting a voltage in which ripple generated in an output voltage waveform is suppressed even during a low load operation in which the voltage is stepped up or down slightly, And it aims at providing the control method.

  A voltage converter according to the present invention drives a switching element to generate an induced voltage in an inductor, thereby converting an input voltage into a predetermined output voltage, and a drive voltage to a control terminal of the switching element. A control unit that outputs and drives the switching element at a predetermined timing, and the control unit outputs a pulse voltage to the pulse voltage output unit and the voltage output from the pulse voltage output unit. And a pulse width variable unit that shortens the pulse width and outputs the driving voltage to the switching element.

  According to the present invention, the switching element can be driven by a voltage having a shorter pulse width than the minimum pulse width that can be output from the pulse voltage output unit. That is, during a light load operation where the voltage is stepped up or down slightly, the input voltage can be transformed to a predetermined output voltage and output while suppressing ripples.

  In the voltage conversion device according to a preferred aspect of the present invention, the control unit outputs a pulse voltage output from the pulse voltage output unit to the switching element as the drive voltage, or the pulse width. It further has an output path switching section that switches to a second output path that outputs a pulse voltage whose pulse width is shortened by the variable section to the switching element as the drive voltage.

  According to this aspect, by switching to the first output path or the second output path, a voltage having a wide pulse width can be output as the drive voltage of the switching element. As a result, the dynamic range that can be stepped up or stepped down by the voltage conversion circuit can be made as wide as possible while suppressing the occurrence of ripples during light load operation.

  The voltage conversion device according to a preferred aspect of the present invention is characterized in that the output path switching unit includes a relay circuit that switches to the first output path or the second output path.

  According to this aspect, since the first and second output paths are autonomously switched according to the load state of the voltage conversion circuit, there is no need to separately provide a microprocessor dedicated to output path switching. Can be suppressed.

  In the voltage conversion device according to a preferred aspect of the present invention, the control unit further includes a voltage difference calculation unit that calculates an input / output voltage difference between the input voltage and the predetermined output voltage, and the output path switching unit includes: When the input / output voltage difference is less than or equal to a threshold value, the second output path is switched.

  According to this aspect, when the input / output voltage difference is equal to or smaller than the threshold value, the voltage conversion circuit outputs a voltage having a short pulse width as the driving voltage of the switching element, assuming that the voltage conversion circuit has transitioned from the heavy load operation to the light load operation. Can do.

  In the voltage conversion device according to a preferred aspect of the present invention, the control unit further includes a pulse width calculation unit that calculates a pulse width of the pulsed voltage output from the pulse voltage output unit, and the output path switching unit includes When the calculated pulse width is equal to or smaller than a threshold value, the second output path is switched.

  According to this aspect, when the pulse width of the voltage output from the pulse voltage output unit is equal to or less than the threshold value, the voltage conversion circuit is assumed to have transitioned from the heavy load operation to the light load operation, and a voltage having a short pulse width is applied to the switching element. Can be output as the drive voltage.

  In the voltage conversion device according to a preferred aspect of the present invention, the voltage conversion circuit converts the input voltage into a predetermined output voltage by driving two or more switching elements for each phase corresponding to each switching element, The control unit outputs a voltage having a pulse width shortened by the pulse width varying unit to the switching element corresponding to at least one phase among the two or more switching elements as the driving voltage.

  According to this aspect, for example, in a multi-phase type voltage conversion process of two or more phases, a switching element corresponding to an arbitrary phase can be driven by a voltage having a shorter pulse width than other phases. it can.

  In the voltage conversion device according to a preferred aspect of the present invention, the control unit is configured for one or more switching elements other than the switching element that outputs a drive voltage from the pulse width variable unit among the two or more switching elements. The output of the drive voltage is stopped.

  According to this aspect, for example, in a multi-phase type voltage conversion process of two or more phases, a switching element corresponding to an arbitrary phase is driven with a voltage having a shorter pulse width than other phases, and the other In this phase, the operation of the switching element can be stopped. Thus, by stopping the operation of one or more switching elements, it is possible to perform more minute voltage conversion while suppressing the generation of ripples.

  In the voltage conversion device according to a preferred aspect of the present invention, the control unit further includes an amplitude variable unit that changes the amplitude of the voltage output from the pulse voltage output unit.

  According to this aspect, by changing the pulse amplitude, the driving current of the switching element can be controlled, and the switching element can be gradually turned on, and the occurrence of ripple can be suppressed.

  In the voltage conversion device according to a preferred aspect of the present invention, the voltage conversion circuit further includes a power supply voltage variable unit that changes a power supply voltage of the switching element.

  According to this aspect, by changing the power supply voltage of the switching element, the switching element can be operated in a smaller operation range, and the occurrence of ripple can be suppressed.

  The present invention is not limited to the voltage converter described above, and can also be understood as a method for controlling the voltage converter.

  According to the present invention, for example, it is possible to provide a voltage conversion device capable of outputting a voltage in which a ripple generated in an output voltage waveform is suppressed even during a light load operation in which the voltage is stepped up or down slightly, and a control method thereof.

It is a figure which shows the circuit structure of the DCDC converter which concerns on 1st Embodiment. It is a wave form diagram for demonstrating operation | movement of a pulse width variable part. It is a figure for demonstrating the voltage fluctuation of the battery mounted in an idling stop vehicle. It is a block diagram which shows the function structure of the DCDC converter which concerns on 2nd Embodiment. It is the figure which showed the range of the pulse width which can be output by a 1st output path | route, and the range of the pulse width which can be output by a 2nd output path | route. It is a figure which shows the specific circuit structure which implement | achieves the function of the DCDC converter which concerns on 2nd Embodiment. It is a flowchart for demonstrating the process which compensates the voltage of the battery mounted in an idling stop vehicle using the DCDC converter which concerns on 2nd Embodiment. It is a figure which shows the specific circuit structure which implement | achieves the function of the DCDC converter which concerns on the 1st modification of 2nd Embodiment. It is a figure which shows the specific circuit structure which implement | achieves the function of the DCDC converter which concerns on the 2nd modification of 2nd Embodiment. It is a figure which shows the specific circuit structure which implement | achieves the function of the DCDC converter which concerns on 3rd Embodiment. It is a flowchart for demonstrating the process performed with the DCDC converter which concerns on 3rd Embodiment.

  A mode for carrying out the present invention (hereinafter referred to as the present embodiment) will be described with a specific example. The present invention relates to a power conversion device that converts an input voltage into a predetermined output voltage by driving a switching element to generate an induced voltage in an inductor.

(1) First Embodiment In the first embodiment, as a specific example of a power converter to which the present invention is applied, a non-insulated type in which an input terminal 111 and an output terminal 112 are not insulated as shown in FIG. The configuration of the DCDC converter 1a will be described.

  As shown in FIG. 1, the DCDC converter 1 boosts the DC input voltage applied to the input terminal 111 to a predetermined DC output voltage and outputs it from the output terminal 112, so that the voltage conversion circuit 120, the control unit 130, Is provided.

  Specifically, the voltage conversion circuit 120 includes a choke coil 121, an FET 122 that is a switching element, a backflow prevention diode 123, and a smoothing capacitor 124. The choke coil 121 has one end connected to the input terminal 111 and the other end connected to the drain terminal of the FET 122 and the anode side of the backflow prevention diode 123. The FET 122 is an N-channel MOSFET whose source terminal is grounded, and has a drain terminal connected to the choke coil 121 and a gate terminal connected to the buffer amplifier 134 of the control unit 130. The backflow prevention diode 123 has an anode connected to the choke coil 121 and the drain terminal of the FET 122, and a cathode connected to the smoothing capacitor 124 and the output terminal 112.

  The voltage conversion circuit 120 having the above connection relationship generates an induced voltage by changing the current flowing through the choke coil 121 according to the on / off operation by the FET 122. The voltage conversion circuit 120 smoothes the output voltage obtained by transforming the input voltage with the induced voltage by the smoothing capacitor 124 via the backflow prevention diode 123 and outputs the smoothed voltage from the output terminal 112.

  The control unit 130 includes a pulse voltage output unit 131, a low-pass filter 132, a diode 133, and a buffer amplifier 134 in order to control the on / off operation of the FET 122.

  The pulse voltage output unit 131 includes a voltage dividing circuit including two resistance elements 131a and 131b connected in series with the output terminal 112, and detects the voltage output from the output terminal 112 by converting the voltage. The pulse voltage output unit 131 is connected to the input terminal 111 and outputs, for example, a voltage that has been subjected to pulse width modulation according to the difference between the input voltage and the output voltage to the low-pass filter 132 side.

  The low-pass filter 132 includes a resistance element 132R and a capacitor 132C. One end of the resistance element 132R is connected to the pulse voltage output unit 131 via the connection point A, and the other end is connected to the capacitor 132C and the buffer amplifier 134 via the connection point B.

  The diode 133 has an anode side connected to the connection point B and a cathode side connected to the connection point A.

  The buffer amplifier 134 buffers the voltage at the connection point B and outputs it as a drive voltage for the FET 122.

  In the control unit 130 configured as described above, the low-pass filter 132, the diode 133, and the buffer amplifier 134 function as the pulse width variable unit 13a that shortens the pulse width of the voltage output from the pulse voltage output unit 131. The voltage waveforms at the connection points A to C are shown in FIG. First, FIG. 2A shows voltage waveforms at connection points A to C when a voltage having a pulse width (normal pulse width) larger than the minimum pulse width dmin is output from the pulse voltage output unit 131. FIG. 2B shows voltage waveforms at connection points A to C when a voltage having a minimum pulse width dmin is output from the pulse voltage output unit 131. As is clear from FIGS. 2A and 2B, the high-frequency component is removed from the voltage waveform at the connection point A by the low-pass filter 132, so that the voltage waveform at the connection point B is a pulse waveform. Since the rising portion becomes gradual, the voltage at the connection point C has a shorter pulse width than the voltage waveform at the connection point A.

  2B, a voltage having a pulse width smaller than the minimum pulse width dmin can be output from the connection point C as the drive voltage of the FET 122. Since the pulse width can be adjusted in this way, the voltage conversion circuit 120 transforms the input voltage to the output voltage and outputs it while suppressing ripples during light load operation where the input voltage is boosted slightly. Can do.

  As a specific example for realizing the above-described ripple suppression, an application example in which the DCDC converter 1 is applied will be described as an application for compensating the voltage of the battery mounted on the idling stop vehicle. First, since the voltage of the battery mounted on the idling stop vehicle drops during the engine restart period T0, the battery voltage is boosted during the voltage drop period indicated by the broken line Vin301 in FIG. It is necessary to output in the waveform. Actually, the voltage does not drop uniformly as shown in FIG. 3 (A), but as shown by the waveform Vin302 in FIG. 3 (B), the battery voltage drops all at once when the engine starts, and then the battery voltage. Gradually recovers. Thus, since the rise time (recovery time) of the battery voltage is longer than the fall time, a period (light load period TL) in which the input voltage is not less than the threshold voltage Vth but not more than the required output (12 V) occurs. This characteristic is unique to vehicles, and the rise time (recovery time) becomes longer depending on the deterioration of the battery. Depending on the deterioration of the battery, the battery voltage cannot be recovered beyond the required output, and it may be necessary to boost the voltage before restarting the engine.

  Here, in the light load operation period TL, it is required to slightly increase the input voltage. For example, when the FET 122 is driven with the voltage having the minimum pulse width dmin of the pulse voltage output unit 131, the ripple is generated. Can occur. On the other hand, the DCDC converter 1 according to the present embodiment can drive the FET 122 with a drive voltage having a pulse width smaller than the minimum pulse width dmin in the light load operation period TL in which a minute boost is required. The input voltage can be transformed into the output voltage and output while suppressing the ripple that may occur in the operation period TL.

(2) Second Embodiment (2-1) Overall Configuration A DCDC converter 1b according to a second embodiment will be described with reference to FIG. FIG. 4 is a block diagram schematically showing the configuration of the DCDC converter 1b. That is, in the DCDC converter 1b, the control unit 130 includes a pulse voltage output unit 131, a pulse width variable unit 13a, a pulse amplitude variable unit 135, an input / output voltage difference detection unit 136, and an output path switching unit 137. . The description of the same configuration as that of the first embodiment is omitted, and the pulse amplitude variable unit 135, the input / output voltage difference detection unit 136, and the output path switching unit 137 will be described below.

  The pulse amplitude variable unit 135 changes the amplitude value of the voltage output from the pulse width variable unit 13 a and outputs the changed value as the drive voltage of the FET 122.

  The input / output voltage difference calculation unit 136 calculates an input / output voltage difference between the input voltage input to the input terminal 111 and the output voltage output from the output terminal 112, and sends the calculation result to the output path switching unit 137. Output.

  The output path switching unit 137 switches to the first output path or the second output path according to the calculation result by the input / output voltage difference calculation unit 136. Here, the first output path is a path for directly outputting the pulse voltage output from the pulse voltage output unit 131 as the drive voltage of the FET 122 without passing through the pulse width variable unit 13a and the pulse amplitude variable unit 135. . The second output path is a path for outputting a pulse voltage whose pulse width is shortened by the pulse width varying unit 13 a as a drive voltage for the FET 122. In the example of FIG. 3 described above, when the input / output voltage difference is equal to or greater than a predetermined threshold value, the output path switching unit 137 causes the FET 122 to operate with a relatively large pulse width drive voltage instead of a light load period. As the one that needs to be driven, the first output path is switched. On the other hand, the output path switching unit 137 is a light load period when the input / output voltage difference is equal to or smaller than a predetermined threshold value, and it is necessary to drive the FET 122 with a drive voltage having a relatively small pulse width. Switch to 2 output path. FIG. 5 is a diagram illustrating the pulse width W on the horizontal axis and the output possible ranges W1 and W2 of the pulse width that can be output for each of the first output path and the second output path on the vertical axis. First, the output possible range W1 of the first output path is a range from the minimum pulse width dmin to the maximum pulse width dmax of the pulse voltage output unit 131. On the other hand, in the second output path, as shown in the output possible range W2, it is possible to output with a pulse width shorter than the minimum pulse width dmin of the pulse voltage output unit 131, but in a region near the maximum pulse width dmax of the pulse voltage output unit 131. Cannot output with pulse width. As apparent from the output possible ranges W1 and W2 shown in FIG. 5, by switching to one of the first output path and the second output path, a voltage having a wide pulse width can be driven. It can be output as a voltage. That is, it is possible to increase the voltage more greatly during heavy load operation while suppressing the occurrence of ripple during light load operation. That is, the dynamic range that can be transformed can be secured as wide as possible.

  A specific circuit configuration for realizing the function of the DCDC converter 1b described above will be described with reference to FIG. In addition, about the structure demonstrated in FIG. 1, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  The pulse amplitude variable unit 135 is realized by a voltage dividing circuit including a variable resistance element 135a and a resistance element 132R of the low-pass filter 132 as shown in FIG. That is, by adjusting the voltage dividing ratio according to the variable resistance element 135a, the amplitude value of the voltage output from the connection point C to the FET 122 is changed. By changing the amplitude value of the voltage in this way, the drive current of the switching element (FET 122) can be controlled, and the switching element (FET 122) can be gradually turned on, thereby suppressing the occurrence of ripple. it can.

  As shown in FIG. 6, the input / output voltage difference detection unit 136 subtracts the output voltage output from the output terminal 112 by the input voltage input from the input terminal 111 through the connection point D and outputs the subtracter 136a. It is realized by. The output (input / output voltage difference) of the subtractor 136a is input to a comparator 137b described later.

  The output path switching unit 137 includes a threshold voltage source 137a, a comparator 137b that compares the threshold voltage of the threshold voltage source 137a with an input / output voltage difference, and a first or second output path according to an output value from the comparator 137b. And a relay circuit 137c for switching to. For example, when the input / output voltage difference exceeds the threshold voltage, the comparator 137b outputs a logic output of “0” and switches the relay circuit 137c to the first output path side. On the other hand, when the input / output voltage difference is equal to or lower than the threshold voltage, a logic output of “1” is output to switch the relay circuit 137c to the second output path side. The output path switching unit 137 configured as described above is configured so that the relay circuit 137c autonomously switches between the first and second output paths in accordance with the input / output difference that is the operation state of the voltage conversion circuit 120. Since there is no need to separately provide a dedicated microprocessor for switching, an increase in the scale of the apparatus can be suppressed.

  Next, a process for compensating for the voltage of the battery mounted on the idling stop vehicle using the DCDC converter 1b will be described with reference to the flowchart shown in FIG.

  In step S701, when the engine start is started from the idling stop (S701: Yes), the process proceeds to step S702. When the engine start is not started (S701: No), the process shown in FIG. 7 is ended.

  In step S702, the output path switching unit 137 switches to the second output path and controls the FET 122. That is, the pulse width variable unit 13 a outputs a voltage with a shortened pulse width as the driving voltage for the FET 122.

  In step S703, when the engine start is finished (S703: Yes), the processing shown in FIG. 7 is finished. If the engine has not been started (S703: No), the process proceeds to step S704.

  In step S704, the output switching unit 137 determines whether or not the voltage conversion circuit 120 is in a light load state. Specifically, the comparator 137b determines whether or not the input / output voltage difference detected by the input / output voltage difference detection unit 136 is equal to or less than a threshold voltage. If the input / output voltage difference is equal to or less than the threshold voltage (S704: Yes), the process returns to step S702. On the other hand, if the input / output voltage difference is not less than or equal to the threshold voltage (S704: No), that is, if the input / output voltage difference exceeds the threshold voltage, the process proceeds to step S705.

  In step S705, the output switching unit 137 switches to the first output path and controls the FET 122. That is, the voltage output from the pulse voltage output unit 131 is directly output as the drive voltage of the FET 122 without passing through the pulse width variable unit 13 a and the pulse amplitude variable unit 135.

  In step S706, when the engine start is finished (S706: Yes), the process shown in FIG. 7 is finished. If the engine has not been started (S706: No), the process returns to step S704.

  According to the process shown in FIG. 7, if the input / output voltage difference exceeds the threshold value, it is regarded as a heavy load operation, and the drive with the relatively long pulse width output from the pulse voltage output unit 131 is switched to the first output path. The FET 122 can be driven by a voltage. On the other hand, when the input / output voltage difference is less than or equal to the threshold value, it is regarded as a light load operation, and the switching element can be driven by the driving voltage with the pulse width variable section 13a shortened.

(2-2) Modification The DCDC converter 1b is not limited to the configuration shown in FIG. 6 described above. For example, as shown in FIG. 8, the voltage conversion circuit 120 includes a choke coil 121 and a drain terminal of the FET 122. A variable inductor 125 connected in between may be provided. The variable inductor 125 functions as a power supply voltage variable unit that changes the drain voltage of the FET 122, that is, the power supply voltage of the FET 122. By changing the power supply voltage of the FET 122 in this manner, the FET 122 can be operated in a smaller operating range, and the generation of ripples can be suppressed.

  Further, the DCDC converter 1b is not limited to the configuration shown in FIGS. 6 and 8 described above, and for example, a configuration as shown in FIG. 9A may be adopted. That is, instead of the input / output voltage difference detection unit 136, the DCDC converter 1b includes a pulse width detection unit 138 that calculates the pulse width of the voltage output from the pulse voltage output unit 131, as shown in FIG. You may prepare. For example, the pulse width calculation unit 138 includes a diode 138a and a capacitor 138b in order to calculate the pulse width of the output voltage of the pulse voltage output unit 131 by converting it into an effective average voltage. The diode 138a has an anode connected to the pulse voltage output unit 131 and a cathode connected to the capacitor 138b. The capacitor 138b averages the voltage output from the pulse voltage output unit 131 via the diode 138a, and applies the effective average voltage to the comparator 137b of the output path switching unit 137. Here, FIG. 9B shows a change in effective average voltage corresponding to a change in the pulse width of the output voltage of the pulse voltage output unit 131. As can be seen from FIG. 9B, the effective average voltage Va increases as the pulse width Width increases, so that the pulse width Width can be calculated by converting the pulse width Width into the effective average voltage Va.

  In the output path switching unit 137, the comparator 137b compares the effective average voltage Va calculated by the pulse width calculation unit 138 with the threshold voltage, and the relay circuit 137c determines whether the first or the output value is output from the comparator 137b. Switch to the second output path. For example, when the effective average voltage Va exceeds the threshold voltage, that is, when the pulse width of the output voltage of the pulse voltage output unit 131 is larger than a predetermined value, the comparator 137b logically outputs “0” and outputs the relay circuit 137c. Is switched to the first output path side. On the other hand, when the effective average voltage is equal to or lower than the threshold voltage, that is, when the pulse width of the output voltage of the pulse voltage output unit 131 is equal to or smaller than the predetermined value, “1” is logically output and the relay circuit 137c is moved to the second output path side. Switch.

  According to the configuration shown in FIG. 9A, when the pulse width of the voltage output from the pulse voltage output unit 131 is equal to or smaller than the threshold value, it is assumed that the voltage conversion circuit 120 is in light load operation, and the pulse width Can be output as the driving voltage of the switching element. On the other hand, when the pulse width of the voltage output from the pulse voltage output unit 131 exceeds the threshold value, it is assumed that the voltage conversion circuit 120 is in heavy load operation, and the relatively pulse signal output from the pulse voltage output unit 131 is relatively high. A voltage having a long width can be directly output as a drive voltage for the FET 122.

(3) Third Embodiment A DCDC converter 1c according to a third embodiment will be described with reference to FIG. The DCDC converter 1c includes a voltage conversion circuit 220 and a control unit 230 in order to convert an input voltage into a predetermined output voltage by driving two or more switching elements for each corresponding phase.

  Specifically, the voltage conversion circuit 220 includes a choke coil 221, a switching element FET 222, and a backflow prevention diode 223 in addition to the same configuration as the voltage conversion circuit 120 of the first embodiment described above. Have. The choke coil 221 has one end connected to the input terminal 111 and the other end connected to the drain terminal of the FET 222 and the anode side of the backflow prevention diode 223. The FET 222 is an N-channel MOSFET whose source terminal is grounded, and has a drain terminal connected to the choke coil 221 and a gate terminal connected to a pulse voltage output unit 231 described later. The backflow prevention diode 223 has an anode connected to the choke coil 221 and a cathode connected to the smoothing capacitor 124 and the output terminal 112.

  In the control unit 230 having the above connection relation, the choke coils 121 and 221 independently input voltages by the FETs 122 and 222 being turned on / off at different phases, specifically, at a timing different in phase by 180 degrees. The transformed output voltage is output to the output terminal 112.

  The control unit 230 includes a pulse voltage output unit 231 and a pulse amplitude unit 13a. The pulse voltage output unit 231 outputs voltages Gate1 and Gate2 having a phase difference of 180 degrees to the pulse width variable unit 13a and the gate terminal of the FET 222.

  Next, a process for compensating for the voltage of the battery mounted on the idling stop vehicle using the DCDC converter 1c will be described with reference to the flowchart shown in FIG.

  In step S1101, when the engine start is started from the idling stop (S1101: Yes), the process proceeds to step S1102, and when the engine start is not started (S1101: No), the process shown in FIG. 11 is terminated.

  In step S1102, the pulse voltage output unit 231 controls the FETs 122 and 222 in multiphase, and proceeds to step S1103. That is, in this step, the pulse voltage output unit 231 outputs the voltages Gate1 and Gate2 in different phases. The voltage Gate 1 is output to the FET 122 with the pulse width variable unit 13 a shortening the pulse width. On the other hand, the voltage Gate2 is directly output to the FET 222 without shortening the pulse width.

  In step S1103, when the engine start is finished (S1103: Yes), the processing shown in FIG. 11 is finished. If the engine has not been started (S1103: No), the process proceeds to step S1104.

  In step S1104, the pulse voltage output unit 231 determines whether or not the voltage conversion circuit 220 has a light load according to the voltage value of the input voltage. If the voltage conversion circuit 220 has a light load (S1104: Yes), for example, if the input voltage exceeds the threshold and a minute boosting operation is required, the process returns to step S1102. On the other hand, when the voltage conversion circuit 220 is not lightly loaded (S1104: No), for example, when the input voltage is equal to or lower than the threshold value and a relatively large boosting operation is required, the process proceeds to step S1105.

  In step S1105, the control unit 230 stops outputting the drive voltage to the FET 222, and outputs the drive voltage only to the FET 122. Specifically, the control unit 230 drives only the FET 122 as a drive voltage using a voltage whose pulse width is shortened by the pulse width variable unit 13a.

  In step S1106, when the engine start is finished (S1106: Yes), the process shown in FIG. 11 is finished. If the engine has not been started (S1106: No), the process returns to step S1104.

  According to the process shown in FIG. 11, in the two-phase multi-phase type voltage conversion process as described above, the FET 122 corresponding to one phase (phase) is compared with the FET 222 corresponding to another phase (phase). And can be driven by a voltage having a shorter pulse width.

  Furthermore, according to the process shown in FIG. 11, the drive voltage is output to the switching element (FET 222) other than the switching element (FET 122) that outputs the drive voltage from the pulse width variable unit, out of the two switching elements. Stop. For example, in a two-phase multi-phase type voltage conversion process, a switching element (FET 122) corresponding to one phase (phase) is driven with a voltage having a short pulse width, and a switching element (FET 222) corresponding to another phase is driven. Stop operation. By such processing, it is possible to perform more minute voltage conversion while suppressing the occurrence of ripple.

  In the third embodiment, two-phase multiphase is used. However, the present invention is not limited to this, and three or four switching elements may be provided to be operated in different phases. That is, a voltage having a pulse width shortened by the pulse width variable unit is output as a drive voltage to a switching element associated with at least one phase among two or more switching elements, and the other switching elements are driven. The voltage output may be stopped.

(4) Others The voltage converter to which the present invention is applied is not limited to the step-up DCDC converter described above, but can be applied to a step-down DCDC converter. The voltage conversion device to which the present invention is applied is the non-insulated device described in the above embodiment as long as the switching element is driven to generate an induced voltage in the inductor and convert the input voltage into a predetermined output voltage. For example, the present invention can be applied to an isolated DCDC converter in which an input terminal and an output terminal are insulated via a transformer.

120 Voltage conversion circuit 121, 221 Choke coil 122, 222 FET
130, 230 Control unit 131, 231 Pulse voltage output unit 13a Pulse width variable unit

Claims (8)

A voltage conversion circuit that converts the input voltage into a predetermined output voltage by driving the switching element and generating an induced voltage in the inductor;
A control unit that outputs a driving voltage to a control terminal of the switching element and drives the switching element at a predetermined timing; and
The controller is
A pulse voltage output unit that outputs a pulsed voltage;
Shortening the pulse width of the voltage output from the pulse voltage output unit, and outputting the driving voltage to the switching element as a pulse width variable unit;
A first output path that outputs the pulse voltage output from the pulse voltage output unit to the switching element as the drive voltage, or a pulse voltage that has a pulse width shortened by the pulse width variable unit as the drive voltage. An output path switching unit that switches to a second output path that outputs to the switching element;
A voltage difference calculator that calculates an input / output voltage difference between the input voltage and the predetermined output voltage;
The output path switching unit switches to the second output path when the input / output voltage difference is equal to or less than a threshold value . A voltage conversion circuit that converts the input voltage into a predetermined output voltage by driving the switching element and generating an induced voltage in the inductor;
A control unit that outputs a driving voltage to a control terminal of the switching element and drives the switching element at a predetermined timing; and
The controller is
A pulse voltage output unit that outputs a pulsed voltage;
Shortening the pulse width of the voltage output from the pulse voltage output unit, and outputting the driving voltage to the switching element as a pulse width variable unit;
A first output path that outputs the pulse voltage output from the pulse voltage output unit to the switching element as the drive voltage, or a pulse voltage that has a pulse width shortened by the pulse width variable unit as the drive voltage. An output path switching unit that switches to a second output path that outputs to the switching element;
A pulse width calculation unit that calculates a pulse width of the pulsed voltage output by the pulse voltage output unit;
The output path switching unit switches to the second output path when the calculated pulse width is equal to or smaller than a threshold value . The output path switching unit, a voltage converter according to claim 1, wherein further comprising a relay circuit to switch to the first output path or the second output path. A voltage conversion circuit that converts the input voltage into a predetermined output voltage by driving the switching element and generating an induced voltage in the inductor;
A control unit that outputs a driving voltage to a control terminal of the switching element and drives the switching element at a predetermined timing; and
The controller is
A pulse voltage output unit that outputs a pulsed voltage;
Shortening the pulse width of the voltage output from the pulse voltage output unit, and having a pulse width variable unit that outputs the driving voltage to the switching element;
The voltage conversion circuit converts an input voltage into a predetermined output voltage by driving two or more switching elements for each phase corresponding to each switching element,
The control unit outputs, as the drive voltage, a voltage whose pulse width is shortened by the pulse width variable unit to a switching element corresponding to at least one of the two or more switching elements. Conversion device. The control unit stops driving voltage output for one or more switching elements other than the switching element that outputs the driving voltage from the pulse width variable unit among the two or more switching elements. The voltage converter according to claim 4 . A voltage conversion circuit that converts the input voltage into a predetermined output voltage by driving the switching element and generating an induced voltage in the inductor;
A control unit that outputs a driving voltage to a control terminal of the switching element and drives the switching element at a predetermined timing; and
The controller is
A pulse voltage output unit that outputs a pulsed voltage;
Shortening the pulse width of the voltage output from the pulse voltage output unit, and outputting the driving voltage to the switching element as a pulse width variable unit;
A voltage converter having an amplitude variable unit that changes the amplitude of the voltage output from the pulse voltage output unit . A voltage conversion circuit that converts the input voltage into a predetermined output voltage by driving the switching element and generating an induced voltage in the inductor;
A control unit that outputs a driving voltage to a control terminal of the switching element and drives the switching element at a predetermined timing; and
The controller is
A pulse voltage output unit that outputs a pulsed voltage;
Shortening the pulse width of the voltage output from the pulse voltage output unit, and having a pulse width variable unit that outputs the driving voltage to the switching element;
The voltage conversion circuit further includes a power supply voltage variable unit that changes a power supply voltage of the switching element. In the control method of the voltage conversion circuit that converts the input voltage into a predetermined output voltage by driving the switching element and generating an induced voltage in the inductor,
A first step of outputting a pulsed voltage;
A second step of shortening the pulse width of the output pulsed voltage and applying it as a drive voltage to the control terminal of the switching element to drive the switching element at a predetermined timing;
The first output path for outputting the pulsed voltage output in the first step to the switching element as the driving voltage, or the switching in which the pulsed voltage whose pulse width is shortened in the second step is the driving voltage. A third step of switching to a second output path that outputs to the element;
A fourth step of calculating an input / output voltage difference between the input voltage and the predetermined output voltage;
The third step includes a step of switching to the second output path when the input / output voltage difference is less than or equal to a threshold value.
A method for controlling a voltage conversion device.

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