JP2740174B2 - Inverter device - Google Patents

Description

Description: TECHNICAL FIELD The present invention has a pair of switching elements, and does not pass through an insulating element such as a transformer from an oscillation circuit having the same potential as one switching element to another switching element having a different potential. And an inverter device for transmitting a signal to the inverter device. (Background Art) FIG. 11 is a circuit diagram of a conventional inverter device, and FIG.
The figure is the operation waveform diagram. A series circuit of switching elements SW ₁ and SW ₂ is connected to both ends of the DC power supply V.
The switching elements SW ₁ and SW ₂ are composed of, for example, power MOS transistors or power bipolar transistors in which diodes are connected in anti-parallel. Each switching element SW
₁ and SW ₂ are turned on / off by output signals V ₁ and V ₂ of the driver circuits ₁ and ₂ , respectively. One switching element SW
The _second ends, via an inductance L _0, a parallel circuit of the load Z and the capacitor C ₀ is connected. As the load Z, for example, a discharge lamp is used. When the load Z is a discharge lamp, the resonance circuit including the inductance L ₀ and the capacitor C ₀ is used in order to make the waveform of the load current into a sine wave from the relation of radiation noise and the like. Each switching element SW ₁ ,
As shown in FIGS. 12 (m) and (l), the currents I ₁ and I ₂ of SW ₂ start in the negative direction and are cut off in the positive direction. This is because the drive frequency of the switching elements SW ₁ and SW ₂ is set higher than the resonance frequency of the resonance circuit formed by the inductance L ₀ and the capacitor C ₀ . When set in this way, for example, when the switching element SW ₁ is turned off, the resonant current by the load circuit, the switching element SW ₂
It will flow initially in the negative direction, followed by flow in the positive direction of the switching element SW _2. Similarly, when the switching element SW ₂ is turned off, the resonant current by the load circuit flows in the first negative switching elements SW _1, followed by flow in the positive direction of the switching elements SW _1. In this case, the device voltage V _5, V ₃ of the switching elements SW _1, SW _2, respectively goes high voltage when off. Resistor R ₁ and capacitor C ₁ connected to both ends of DC power supply V
The series circuit is a power supply circuit of the lower circuit including the oscillation circuit 5 and the driver circuit 2, resistors R ₂ are connected to both ends of the switching elements SW _1, the upper circuit a series circuit of a capacitor C _2, including a driver circuit 1 Power supply circuit. Capacitor
C ₃ and C ₄ are capacitance components of the switching elements SW ₁ and SW ₂ . Oscillator 5 powered by the capacitor C _1, the two drive signals V _A, and outputs the V _B. The drive signal V _A is input to the driver circuit 2, a drive signal V _B via the signal transmission circuit, is inputted to the driver circuit 1. The signal transmission circuit includes transistors Tr ₁ , Tr ₂ , Tr ₃ , Tr ₄ , a diode D ₁ ,
It consists resistor R _3, and performs signal transmission without using an insulating element of transformer or the like. The transistors Tr ₁ and Tr ₂ constitute a current mirror circuit 3, and the transistors Tr ₃ and Tr ₄ constitute a current mirror circuit 4. Drive signal V _B output from the oscillation circuit 5 is inputted to one of the transistor Tr ₁ of the current mirror circuit 3, the other output of the transistor Tr ₂ of the current mirror circuit 3, one of the transistors Tr of the current mirror circuit 4 ₃ is entered. Other transistor Tr ₄ of the current mirror circuit 4 is connected to resistor R ₃ in series, it is connected across the capacitor C _2. When the current amplification factor hfe of each transistor Tr ₁ to Tr ₄ is made sufficiently large, the transistor Tr ₂ almost the same current as the input current I _B 'to flow by the drive signal V _B to the transistor Tr ₁ as the signal transmission current I _B, it flows in Tr _3, also almost the same current as the signal transmission current I _B flowing through the transistor Tr ₃ flows as the output current I ₄ to the transistor Tr _4. When the drive signal V _B is high, the transistors Tr _1, Tr
₂ becomes conductive, the signal transmission current I _B flows through the transistor T
r ₃ and Tr ₄ also conduct. When the transistor Tr ₄ is conductive, resistor R ₃ output current I ₄ flows in the voltage across drop occurs in the resistor R _3, the input signal V ₄ of the driver circuit 1 becomes a high level.
When the drive signal V _B is low, the driver circuit 1
Input signal V ₄ of a low level. The transistors Tr ₁ to Tr ₄ of the current mirror circuits 3 and 4 in order to perform high-speed operation, operating in an unsaturated region. Diode D ₁ when the transistor Tr ₂ is turned off,
To form a bypass path for releasing charged accumulated charges in the stray capacitance component Cs between the collector and emitter of the transistor Tr _2, it is provided to reduce the base-emitter reverse voltage of the transistor Tr _3. In this conventional example, without using a transformer and an insulating element such as a photocoupler, the oscillation circuit 5 to the driver circuit 1 of different potential side, it is possible to transmit the input signal V ₄ in synchronization with the drive signal V _B The configuration is suitable for the control circuit being integrated into an IC. However, in this conventional example, when the drive signal V _B is low, when the element voltage V ₃ increases, through one of the transistor Tr ₃ of the capacitor C ₂ and the current mirror circuit 4, the transistor Tr and charge current to the _second capacitive component Cs flows, which without the effects such as signal transduction current I _B, there may occur a malfunction. Hereinafter, this operation will be described with reference to FIG. First, the drive signal V _B at time t ₀ (Fig. 12 (b))
Becomes low, the current of the current mirror circuits 3 and 4
I _B ′, I _B , I ₄ (FIGS. (C), (d), (e)) stop flowing, and the input signal V ₄ (FIG. (F) of the driver circuit 1) is at a low level. output signals V ₁ (FIG. (h)) becomes low level, the switching element SW ₁ is turned off. in this case, the device voltage V _3, V _5, current I _2, I ₁ (FIG. (i),
(J), (l) and (m)) are switching elements SW ₁ and SW ₂
The current changes in a gradient manner due to the capacitance components C ₃ and C ₄ , and after time t ₁ , the current flows as a negative current I ₂ ((l) in the figure) due to the resonance action of the load circuit, and at time t 1 ₂ and later, and the switching element SW ₂ is turned on by the drive signal V _a (FIG. (a)) becomes high level, eventually it flows in the forward direction. With the reduction of the element voltage V _3, also decreases in synchronism charging voltage V ₆ of the stray capacitance Cs of the transistor Tr ₂ of the current mirror circuit 3 (FIG. (K)), the discharge of charge from the capacitance component Cs is takes place via the diode D ₁ and capacitor C _2. At time t _3, when the drive signal V _A becomes low level, the output signal V ₂ (FIG. (G)) of the driver circuit 2 becomes low level, the switching element SW ₂ is turned off, element by resonance of the load circuit voltage V ₃ is going to rise. In this case, the capacitance component Cs is charged through the current mirror circuit 4, rises also its charge voltage V _6. Here, the charging current from the current mirror circuit 4 to the capacitive component Cs, it means that flows through the same path as the signal transmission current I _B due to the drive signal V _B, and the flow output current I _4, to the driver circuit 1 level of the input signal V ₄ increases, the driver at time t ₄ circuit 1
Output signal V ₁ is a high level. Hence the switching element
SW ₁ is turned on, since the device voltage V _3, V ₅ is the point in the middle of changing, rapid charging and discharging of the capacitance component C _3, C ₄ is performed. This current has a high peak value and causes switching loss, sometimes causing destruction of the switching elements SW ₁ and SW ₂ and generation of noise. Because after time t ₅ the drive signal V _B becomes high level, the switching element
SW ₁ keeps on, and current I ₁ (FIG. 12 (m)) flows in the positive direction. Drive signal V _B goes low at time t _6, turns off the switching element SW ₁ again, the following is for supplying radio frequency power to a load circuit in this repetition. As understood from the above description, in the conventional example, even drive signal V _B is a low level, the device voltage V ₃
And the charging current to the capacitive component Cs flow by increasing, for this to act as if it were a signal transmission current I _B, there is a problem that the switching element SW ₁ is thus turned on, improved reliability is desired I was (Objects of the Invention) The present invention has been made in view of the above points, and an object of the present invention is to make it possible for a charging current to a capacitance component of a signal transmission circuit to act like a signal transmission current. It is an object of the present invention to provide an inverter device with improved reliability by preventing the above. (Disclosure of the Invention) The configuration of the inverter device according to the present invention will be described with reference to the embodiment of FIG. 1. A DC power supply V and first and second switching elements SW ₁ and SW ₂ connected to both ends of the DC power supply. of a series circuit, the first and the smoothing capacitor C ₂ to the negative electrode side is connected to said first and second connecting point of the switching elements SW _1, SW _2, is connected to the first ends of the smoothing capacitor C ₂ A first driver circuit 1 for turning on and off the _first switching element SW1 connected to the positive side of the DC power supply V, and a second driver circuit having the negative side connected to the same potential as the _second switching element SW2. the smoothing capacitor C _1, is connected to the second ends of the smoothing capacitor C _1, the first switching element SW ₁ at the same time as the so as not to turn on the second of the second driver for turning on and off the switching element SW ₂ Circuit 2 and the second Connected across the smoothing capacitor C ₁
An oscillation circuit for outputting a drive signal to the first and second driver circuits; and a resonance circuit connected to at least one end of at least one of the _first and _second switching elements. And the oscillation circuit 5
And a signal transmission circuit that transmits a drive signal to a signal input terminal of the first driver circuit 1, wherein the signal transmission circuit is turned on and off by receiving an output of the oscillation circuit 5. and _2), the third interlocking operation by receiving an output signal of the switching element, the positive electrode side and the first of said first smoothing capacitor C ₂
And a fourth switching element (Tr ₄ ) interposed between signal input terminals of the driver circuit of ( ₁ ), wherein the third switching element (Tr ₂ ) is turned off when the first switching element (Tr ₂ ) is turned off. wherein said resonant circuit below the level that can maintain the oFF state of the SW ₁ first smoothing capacitor
It is characterized in the provision of the impedance element which can limit the current through the C ₂ to closed circuit comprising a signal transmitting circuit to the signal transmission circuit. According to the present invention, with such a configuration, it is possible to prevent an unnecessary switching element current from flowing when the voltage between both ends of the switching element changes, thereby improving reliability. Hereinafter, examples of the present invention will be described. In the circuit of the embodiment, portions having the same functions as those of the circuit of the conventional example are denoted by the same reference numerals, and redundant description will be omitted. Embodiment 1 FIG. 1 is a circuit diagram of one embodiment of the present invention, and FIG. 2 is an operation waveform diagram thereof. In the present embodiment, in the conventional example of FIG. 11, a capacitor is used as an impedance element that bypasses the current charged in the capacitance component Cs of the signal transmission circuit so as not to be transmitted to the _first switching element SW1.
Provided with a C _5, in which provided as an impedance element so that the current to be charged in the capacitance component Cs does not easily flow in the path of the signal transfer current I _B, a resistor Ra. Hereinafter, the operation will be described with reference to FIG. At time t ₀ , the drive signal V _B (FIG. 2 (b))
Becomes low, the currents I _B ′, I _B , I ₄ (FIG.
(D) and (e)) cease to flow, the input signal V ₄ ((g) in the figure) to the driver circuit 1 becomes low, and the output signal V ₁ ((i) in the figure) of the driver circuit 1 becomes low. level so that the switching element SW ₁ is turned off. The element voltage V ₃ ((j) in the figure) decreases gradually due to the capacitance components C ₃ and C _{4 of the} switching elements SW ₁ and SW ₂ . Also, the accumulated charge of the capacitance component Cs, in the path through the diode D ₁ to the resistor Ra is present because hardly discharges, discharges through capacitor C _5. As a result, the charging voltage V ₆ of the capacitance component Cs ((k) in the figure)
Decreases. Current flowing in the load circuit and tries to continue to flow by the resonance of the LC components, after time t ₁ flows through the switching element SW ₂ in the negative direction. Time t ₂ after the driver signal V _A (FIG. (A)) becomes high level, the output signal V ₂ (FIG. (H)) of the driver circuit 2 becomes the high level, the switching element SW ₂ is turned on Eventually the current I ₂
((L) in the figure) flows in the forward direction. When at time t ₃ drive signal V _A becomes low, the element voltage V ₃ and the charging voltage V ₆ increases inclined manner. Current flowing in the load circuit and will continue to flow through the resonance effect, the time t ₄ after flowing through the switching element SW ₁ in the negative direction, up to this time, the charging voltage V _6, the device voltage V ₃ is being increased . The charging current required to charge the voltage V ₆ of capacitor component Cs is increased, without for resistance Ra is present through transistor Tr _3, Tr _4, the current I _C5 of the capacitor C ₅ of the bypass (FIG ( f)) flows as Therefore, the signal transfer current I _B, unnecessary signal due to the charging of the capacitance component Cs is not added, there is no possibility that the output signal V ₁ of the driver circuit 1 becomes a high level. in this way,
In this embodiment, by inserting the resistor Ra, the charging current of the capacitive component Cs is thereby prevented from flowing in the current mirror circuit 4, by bypassing the charge current through the capacitor C _5, the charging current the one in which the switching element SW ₁ was prevented from being turned on. The time t ₅ after the drive signal V _B becomes a high level, current
I _B ', I _B, and I ₄ flows, the input signal V ₄ of the driver circuit 1 becomes a high level, the output signal V ₁ also becomes high level, the switching element SW ₁ is turned on, eventually the current I ₁ ((m) in the figure) flows in the forward direction. Again drive signal at a time t ₆
V _B goes low, below, and supplies power to the load Z in this repetition. Note that an impedance element such as a choke coil may be used instead of the resistance Ra. If the impedance of the current mirror circuit 4 is very high as compared with the impedance element for bypass (capacitor C ₅ ), the resistance may be reduced. Ra may be omitted. Embodiment 2 FIG. 3 (a) is a main part circuit diagram of a second embodiment of the present invention. In the present embodiment, by changing the connection position of the diode D _1, it is obtained by utilizing a junction capacitance Cj of the diode D ₁ as the impedance of the bypass. Further, FIG. 3 (b) is an essential part circuit diagram of a variation of this embodiment, connected in parallel to capacitor C ₅ and the diode D _1, it is obtained by further reducing the impedance of the bypass. Embodiment 3 FIG. 4 is a main part circuit diagram of a third embodiment of the present invention. In the present embodiment, the charging current to the capacitance component Cs is supplied via the charging resistor Rb connected to the DC power supply V. Note that a capacitor or a choke coil may be used instead of the resistor Rb. Embodiment 4 FIG. 5 is a circuit diagram of a fourth embodiment of the present invention. In the present embodiment, in parallel with the capacitance component Cs of the transistor Tr ₂ in the current mirror circuit 3 is obtained by connecting a capacitor C ₈ for voltage fluctuation suppression. FIG. 6 is an operation waveform diagram of the present embodiment. Be the device voltage V ₃ at time t ₀ ~t ₁ (FIG. 6 (h)) is decreased, the charging voltage V ₆ (FIG. (I)) of the capacitance component Cs and the capacitor C ₈ is hardly lowered. Accordingly, even the device voltage V ₃ at time t ₂ ~t ₃ is performed increases,
Since the charge voltage V ₆ originally high capacitance component Cs and the capacitor C _8, those little charging current flows, unwanted signals no longer be generated in the input signal V ₄ of the driver circuit 1. Embodiment 5 FIG. 7 is a circuit diagram of a fifth embodiment of the present invention. In the present embodiment, the signal transmission path between the current mirror circuit 3 and 4, is obtained by inserting the diode D ₂ for preventing reverse flow, thereby, the charge accumulated in the capacitive component Cs and the capacitor C ₈ , even when lowering of the element voltage V _3, it is obtained as hardly reduced. FIG. 8 is an operation waveform diagram of the present embodiment. Time t ₀ ~t be ₁ in the device voltage V ₃ (Fig. (H)) is decreased, the charging voltage V of the capacitive component Cs and the capacitor C _8
6 (Fig. 8 (i)) shows little decrease. Further, when the charging voltage V ₆ by the capacity component Cs and a diode D ₂ is stabilized, the capacitor C ₈ is not necessarily used in particular. Therefore, even if the rise of the element voltage V ₃ at time t ₂ ~t _3, the charging voltage V ₆ originally high capacitance component, not little charging current flows, the same effect as in Example 4. Embodiment 6 FIG. 9 is a main part circuit diagram of a sixth embodiment of the present invention. In the present embodiment, as the impedance element to prevent the decrease in the accumulated charge of the capacitor component Cs, those using resistance Rb in place of the capacitor C ₈ of Figure 7. This resistance Rb
Acts as an impedance element for keeping the capacitance component Cs charged by the DC power supply V.
V ₃ does not decrease most, the charge voltage V ₆ decreases. Therefore, thereafter, even if the rise of the element voltage V _3, the capacitance component Cs
Almost no charging current flows. The impedance element for continuously charging the capacitance component Cs is not limited to the resistor Rb, but may be a capacitor or a choke coil. The charging voltage by the capacitance component Cs and a diode D ₂
When V ₆ is stabilized, it goes without saying that the resistor Rb need not be provided. In each of the above-described embodiments, the current mirror circuits 3 and 4 operating in the unsaturated region are used as the signal transmission circuits, but the transistors Tr ₂ and Tr ₂ shown in FIG. 10 are used.
Even when using a saturation type switching circuit by ₄ ,
The present invention can be applied. In the signal transmission circuit shown in FIG. 10, the transistor Tr ₄ is connected to resistor R _7, R ₃ in series, is connected across the capacitor C ₂ (not shown). Between the base and emitter of the transistor Tr _4, the resistance R ₆ is connected. The base of the transistor Tr ₄ is connected through a resistor R _5, is connected to the collector of the transistor Tr _2. When the drive signal V _B is high,
And a base current flows to the transistor Tr ₂ via the resistor R _4, the transistor Tr ₂ is turned on. At this time, current flows through the resistor R _6, the voltage generated in the resistor R _6, transistor Tr ₄ is turned on, current flows through the resistor R _7, R _3, resistors R _7, R
₃ signal V ₄ occurs in the connection point, a high level signal is input to the driver circuit 1 (not shown). Drive signal V _B is at the low level, the low level signal is input to the driver circuit 1. In such a signal transmission circuit, when the transistor Tr ₂ is turned off, because the erroneous operation due to the charging current to the capacitance component Cs between the collector and the emitter occurs, it is meaningful to apply the present invention. In addition, the inverter device of the full bridge configuration, that is,
The series circuit of the third and fourth switching elements is connected in parallel with the DC power supply V, and the load circuit is connected between the connection point of the first and second switching elements and the connection point of the third and fourth switching elements. The present invention can also be applied to an inverter device which is connected to a power supply circuit and turns on and off switching elements in diagonal directions simultaneously to supply an alternating current to a load circuit. (Effects of the Invention) As described above, the present invention provides a DC power supply, a series circuit of first and second switching elements connected to both ends of the DC power supply, and a negative electrode of the first and second switching elements. A first smoothing capacitor connected to a connection point;
A first driver circuit connected to both ends of the smoothing capacitor for turning on and off the first switching element connected to the positive side of the DC power supply, and a negative side connected to the same potential as the second switching element. A second smoothing capacitor; a second driver circuit connected to both ends of the second smoothing capacitor, for turning on and off the second switching element so as not to be turned on simultaneously with the first switching element; An oscillation circuit connected to both ends of the smoothing capacitor for outputting a drive signal to the first and second driver circuits, and a resonance circuit connected to at least one end of the first or second switching element. A load circuit comprising:
A signal transmission circuit for transmitting a drive signal to a signal input terminal of the driver circuit, wherein the signal transmission circuit is turned on / off by receiving an output of the oscillation circuit, and the third switching element An interlocking operation in response to the output signal of the first and the second switching element interposed between the positive electrode side of the first smoothing capacitor and a signal input terminal of the first driver circuit. When the third switching element is off,
An impedance element capable of limiting a current flowing through a closed circuit including the resonance circuit, the first smoothing capacitor, and the signal transmission circuit to a level equal to or lower than a level at which the first switching element can maintain an off state. Since the switching element is provided in the circuit, it is possible to prevent an unnecessary switching element current from flowing when the voltage between both ends of the switching element changes, and it is possible to improve reliability.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram of one embodiment of the present invention, FIG. 2 is an operation waveform diagram of the embodiment, and FIG. 3 (a) is a main part circuit diagram of a second embodiment of the present invention. FIG. 4B is a circuit diagram of a main part of a modification of the above embodiment, and FIG.
FIG. 5 is a circuit diagram of a main part of a third embodiment of the present invention, FIG. 5 is a circuit diagram of a fourth embodiment of the present invention, FIG. 6 is an operation waveform diagram of the same, and FIG. FIG. 8 is an operation waveform diagram of the same, FIG. 9 is a main part circuit diagram of a sixth embodiment of the present invention,
FIG. 10 is a circuit diagram of another signal transmission circuit used in the present invention, and FIG.
FIG. 11 is a circuit diagram of a conventional example, and FIG. 12 is an operation waveform diagram of the same. V is a DC power supply, SW ₁ and SW ₂ are switching elements, 3 and 4 are current mirror circuits, 5 is an oscillation circuit, V _A and V _B are drive signals, Ra and Rb are resistors, Cs is a capacitance component, C ₅ , C ₈ is a capacitor.

Claims (1)

(57) [Claims] A DC power supply; a series circuit of first and second switching elements connected to both ends of the DC power supply; a first smoothing capacitor having a negative electrode side connected to a connection point of the first and second switching elements; A first driver circuit connected to both ends of the first smoothing capacitor for turning on and off the first switching element connected to a positive electrode side of the DC power supply; and a negative electrode side having the same potential as the second switching element. A second smoothing capacitor connected to both ends of the second smoothing capacitor;
The second switching element so as not to turn on at the same time as the switching element.
A second driver circuit for turning on and off the switching element, and a first driver circuit connected to both ends of the second smoothing capacitor,
An oscillation circuit that outputs a drive signal to the second driver circuit; a load circuit that is connected to at least one of both ends of the first or second switching element and includes a resonance circuit; A signal transmission circuit for transmitting a drive signal to a signal input terminal of the first driver circuit, wherein the signal transmission circuit is turned on / off by receiving an output of the oscillation circuit, and the third switching element is turned on / off. In response to the output signal of the element, it operates in conjunction with the first
And a fourth switching element interposed between the positive side of the smoothing capacitor and the signal input terminal of the first driver circuit, wherein the third switching element is turned off when the third switching element is turned off. An impedance element capable of limiting a current flowing in a closed circuit including the resonance circuit, the first smoothing capacitor, and the signal transmission circuit to a level that can maintain an OFF state of a switching element or less is provided in the signal transmission circuit. An inverter device, characterized in that: 2. 2. The inverter device according to claim 1, wherein the impedance element includes a resistor inserted between a signal output terminal of a third switching element and a signal input terminal of a fourth switching element. . 3. 2. The inverter device according to claim 1, wherein the impedance element includes a capacitor interposed between a positive electrode side of the first smoothing capacitor and a signal output terminal of a third switching element. . 4. 2. The inverter device according to claim 1, wherein the impedance element includes a resistor inserted between a signal output terminal of a third switching element and a positive electrode of the DC power supply. 5. 2. The device according to claim 1, wherein the impedance element includes a capacitor interposed between a signal output terminal of a third switching element and a negative electrode of the DC power supply.
The inverter device according to the item. 6. 2. The impedance element according to claim 1, wherein the impedance element includes a diode having a cathode connected to a signal output terminal of a third switching element and an anode connected to a signal input terminal of a fourth switching element. The inverter device as described.