Semiconductor switch driving circuit and power converter

Abstract

A semiconductor switch drive circuit includes a drive power source and a semiconductor switch drive unit. The semiconductor switch driving unit has a connection switching unit, a capacitor that generates a positive voltage, a capacitor that stores power, and a capacitor that generates a negative voltage. The connection switching unit alternately switches between a first connection state in which a positive voltage application closed circuit for applying a positive voltage to the gate terminal of the semiconductor switch is formed, and a second connection state in which a negative voltage application closed circuit for applying a negative voltage to the gate terminal of the semiconductor switch is formed. A movement restriction unit is provided between the drive power source and the semiconductor switch, the movement restriction unit restricting the movement of the charge from a path flowing through the positive voltage application closed circuit to another path passing through the positive electrode terminal of the capacitor and not passing through the gate terminal of the semiconductor switch.

Description

Technical Field

[0001] The present disclosure relates to a semiconductor switch driving circuit and a power converter. Background Art

[0002] Patent Documents 1 to 3 disclose semiconductor switch drive circuits for driving semiconductor switches. Such semiconductor switch drive circuits are used, for example, in power converters such as inverters. As the semiconductor switch, for example, a normally-off semiconductor switch can be used. In this case, in order to reliably control the semiconductor switch to an off state, it is required to supply a negative voltage to the semiconductor switch. Patent Document 1 discloses a structure in which, in addition to a drive power supply that generates a positive voltage, a drive power supply that generates a negative voltage is added. However, among the components constituting the semiconductor switch drive circuit, the size and weight of such a drive power supply are also relatively large. Therefore, the drive power supply may lead to an increase in the size and weight of the device.

[0003] Patent document 2 discloses a circuit structure capable of generating both positive voltage and negative voltage using one driving power supply. In this circuit structure, a positive power supply capacitor that generates a positive voltage by charging with power from a driving power supply, and a negative power supply capacitor that generates a negative voltage by charging with power from a positive power supply capacitor. These positive and negative voltages are applied alternately to a semiconductor switch. In this circuit structure, since a driving power supply that generates a negative voltage does not need to be separately provided, the size and weight increase of the device can be suppressed. Patent document 3 discloses a circuit structure in which, in addition to the circuit structure described in patent document 2, a negative power supply buffer capacitor that stores power for generating a negative voltage is added. In this circuit structure, the negative power supply capacitor is not charged directly through the positive power supply capacitor, but is charged via the negative power supply buffer capacitor.

[0004] Patent Document 1: Japanese Patent Application Laid-Open No. 8-186976

[0005] Patent Document 2: Japanese Patent Application Publication No. 2018-33303

[0006] Patent Document 3: Japanese Patent Application Publication No. 2019-75887

[0007] In the semiconductor switch drive circuit disclosed in Patent Document 3, when a positive voltage is applied to the semiconductor switch, the movement path of the charge flowing through the positive power supply capacitor and the semiconductor switch becomes a path that does not pass through the third capacitor. In this case, when a positive voltage is applied to the semiconductor switch, the positive voltage of the positive power supply capacitor is avoided to be divided to the semiconductor switch and the negative power supply capacitor. Thus, the reduction of the positive voltage of the positive power supply capacitor can be suppressed. However, in the semiconductor switch drive circuit, in addition to the voltage division of the positive voltage caused by the negative power supply capacitor, there may also be a main factor that reduces the positive voltage of the positive power supply capacitor. Therefore, from the perspective of suppressing the reduction of the positive voltage applied to the semiconductor switch, there is room for improvement. Summary of the invention

[0008] The present disclosure describes a semiconductor switch drive circuit and a power converter that can effectively suppress a decrease in a positive voltage applied to a semiconductor switch.

[0009] A semiconductor switch driving circuit according to one embodiment of the present disclosure includes: a driving power supply; and a semiconductor switch driving unit electrically connected to the driving power supply and driving the semiconductor switch using power from the driving power supply. The semiconductor switch driving unit includes: a connection switching unit electrically connected between the driving power supply and the semiconductor switch and switching the connection state of the semiconductor switch; a first capacitor electrically connected between the driving power supply and the connection switching unit and charged with power from the driving power supply to generate a positive voltage for turning the semiconductor switch on; a second capacitor electrically connected to the driving power supply in parallel with the first capacitor and charged with power from the driving power supply; and a third capacitor electrically connected between the second capacitor and the connection switching unit and charged with power discharged from the second capacitor in a charged state to generate a negative voltage for turning the semiconductor switch off. The connection switching unit alternately switches between a first connection state in which a positive voltage application closed circuit for applying a positive voltage to the control terminal of the semiconductor switch is formed by electrical connection between the positive terminal of the first capacitor and the control terminal of the semiconductor switch, and a second connection state in which a negative voltage application closed circuit for applying a negative voltage to the control terminal of the semiconductor switch is formed by electrical connection between the negative terminal of the third capacitor and the control terminal of the semiconductor switch. A movement limiting unit is provided between the first capacitor and the semiconductor switch, and the movement limiting unit limits the movement of the charge of the first capacitor from the path passing through the positive voltage application closed circuit to another path passing through the positive terminal of the first capacitor and not passing through the control terminal of the semiconductor switch.

[0010] According to the present disclosure, a semiconductor switch drive circuit and a power converter are provided that can effectively suppress a decrease in a positive voltage applied to a semiconductor switch. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 1 is a circuit diagram showing a power converter according to the first embodiment.

[0012] Figure 2 Yes Figure 1 A diagram illustrating the operation of a semiconductor switch driving circuit included in a power converter.

[0013] Figure 3 Yes Figure 1 A diagram illustrating the operation of a semiconductor switch driving circuit included in a power converter.

[0014] Figure 4 Yes Figure 1 A diagram illustrating the operation of a semiconductor switch driving circuit included in a power converter.

[0015] Figure 5 Yes Figure 1 A diagram illustrating the operation of a semiconductor switch driving circuit included in a power converter.

[0016] Figure 6 Yes means Figure 1 A circuit diagram of a modified example of the power converter.

[0017] Figure 7 1 is a circuit diagram showing a power converter according to a second embodiment.

[0018] Figure 8 Yes Figure 7 A diagram illustrating the operation of a semiconductor switch driving circuit included in a power converter.

[0019] Fig. 9 Yes Figure 7 A diagram illustrating the operation of a semiconductor switch driving circuit included in a power converter.

[0020] Fig.10 Yes Figure 7 A diagram illustrating the operation of a semiconductor switch driving circuit included in a power converter.

[0021] Fig.11 Yes Figure 7 A diagram illustrating the operation of a semiconductor switch driving circuit included in a power converter.

[0022] Fig.12 This is a diagram for explaining the problems that a power converter according to a comparative example has. DETAILED DESCRIPTION

[0023] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. In the description of the drawings, the same reference numerals are given to the same elements, and repeated descriptions are omitted.

[0024] A semiconductor switch driving circuit according to one embodiment of the present disclosure includes: a driving power supply; and a semiconductor switch driving unit electrically connected to the driving power supply and driving the semiconductor switch using power from the driving power supply. The semiconductor switch driving unit includes: a connection switching unit electrically connected between the driving power supply and the semiconductor switch and switching the connection state of the semiconductor switch; a first capacitor electrically connected between the driving power supply and the connection switching unit and charged with power from the driving power supply to generate a positive voltage for turning the semiconductor switch on; a second capacitor electrically connected to the driving power supply in parallel with the first capacitor and charged with power from the driving power supply; and a third capacitor electrically connected between the second capacitor and the connection switching unit and charged with power discharged from the second capacitor in a charged state to generate a negative voltage for turning the semiconductor switch off. The connection switching unit alternately switches between a first connection state in which a positive voltage application closed circuit for applying a positive voltage to the control terminal of the semiconductor switch is formed by electrical connection between the positive terminal of the first capacitor and the control terminal of the semiconductor switch, and a second connection state in which a negative voltage application closed circuit for applying a negative voltage to the control terminal of the semiconductor switch is formed by electrical connection between the negative terminal of the third capacitor and the control terminal of the semiconductor switch. A movement limiting unit is provided between the first capacitor and the semiconductor switch, and the movement limiting unit limits the movement of the charge of the first capacitor from the path passing through the positive voltage application closed circuit to another path passing through the positive terminal of the first capacitor and not passing through the control terminal of the semiconductor switch.

[0025] In the semiconductor switch drive circuit, a positive voltage is generated in the first capacitor by power from a drive power source, and a negative voltage is generated in the third capacitor by power discharged from a second capacitor in a charged state. That is, a positive voltage and a negative voltage are generated using one drive power source. Moreover, the first connection state of a positive voltage application closed circuit in which the positive voltage of the first capacitor is applied to the control terminal of the semiconductor switch and the second connection state of a negative voltage application closed circuit in which the negative voltage of the third capacitor is applied to the control terminal of the semiconductor switch are alternately switched by a connection switching unit, thereby alternately switching the connection or disconnection of the semiconductor switch. In the semiconductor switch drive circuit, a second capacitor for charging the third capacitor is provided. Thus, it is not necessary to configure a third capacitor on the positive voltage application closed circuit in which the positive voltage of the first capacitor is applied to the control terminal of the semiconductor switch for charging the third capacitor. Thus, it is possible to avoid the situation where the positive voltage of the first capacitor is divided to the semiconductor switch and the third capacitor. In addition, in the semiconductor switch drive circuit, a movement limiting unit is provided, which limits the movement of the charge of the first capacitor from the path flowing through the positive voltage application closed circuit to other paths passing through the positive terminal of the first capacitor and not passing through the control terminal of the semiconductor switch. This can also prevent the positive voltage of the first capacitor from being divided to circuit elements on other paths. Therefore, in the semiconductor switch drive circuit, it is possible to effectively prevent the positive voltage applied from the first capacitor to the semiconductor switch from decreasing.

[0026] In some embodiments, the movement limiting portion may also have: a first connection point between the positive terminal of the first capacitor and the control terminal of the semiconductor switch; a second connection point between the positive terminal of the second capacitor and the input terminal of the semiconductor switch; a third connection point, which is arranged between the first connection point and the positive terminal of the driving power supply and is electrically connected to the positive terminal of the driving power supply; a first wiring, which connects the first connection point and the third connection point; and a second wiring, which connects the second connection point and the third connection point. In this way, when a third connection point is provided between the first connection point and the driving power supply, it is possible to allow the charge to move from the driving power supply via the third connection point and the first connection point to the first capacitor, while avoiding the charge released from the first capacitor from moving via the first connection point and the third connection point to the second connection point. Thus, it is possible to avoid the charge of the first capacitor moving in the positive voltage application closed circuit from the first connection point to other paths via the second connection point. As a result, it is possible to more effectively suppress the reduction of the positive voltage applied from the first capacitor to the semiconductor switch.

[0027] In some embodiments, the movement limiting portion may also include: a first diode, which is connected in the first wiring in a forward direction from the third connection point toward the first connection point; and a second diode, which is connected in the second wiring in a forward direction from the third connection point toward the second connection point. By setting the first diode and the second diode in this way, it is possible to avoid the situation where the charge from the first capacitor and the second capacitor flows back to the driving power supply. In addition, by setting the first diode between the third connection point and the first connection point, it is possible to avoid the situation where the charge of the first capacitor moves from the first connection point to the second connection point via the third connection point. As a result, it is possible to avoid the charge of the first capacitor from moving to other paths via the second connection point, thereby more effectively suppressing the reduction of the positive voltage applied from the first capacitor to the semiconductor switch.

[0028] In some embodiments, the movement limiting portion may also include: a first resistor element, which is connected in series with the first diode in the first wiring; and a second resistor element, which is connected in series with the second diode in the second wiring and has a higher resistance value than the first resistor element. There is a tendency that the negative voltage used to turn the semiconductor switch into an off state is smaller than the positive voltage used to turn the semiconductor switch into an on state. In this way, when the negative voltage is small, the charge amount of the second capacitor for charging the power for generating the negative voltage can be smaller than the charge amount of the first capacitor for charging the power for generating the positive voltage. Therefore, in the above structure, the second resistor element arranged on the moving path of the charge flowing from the driving power supply to the second capacitor has a higher resistance value than the resistance value of the first resistor element arranged on the moving path of the charge flowing from the driving power supply to the first capacitor. As a result, the charging current supplied from the driving power supply to the second capacitor can be suppressed to be smaller. As a result, the increase in the capacity of the driving power supply that provides power to the second capacitor can be suppressed.

[0029] In some embodiments, the positive terminal of the first capacitor may also be electrically connected to the positive terminal of the driving power supply and the control terminal of the semiconductor switch. The positive terminal of the second capacitor may also be electrically connected to the positive terminal of the driving power supply. The negative terminal of the third capacitor may also be electrically connected to the negative terminal of the second capacitor. The positive terminal of the third capacitor may also be electrically connected to the control terminal of the semiconductor switch. In this case, a structure for generating positive and negative voltages using one driving power supply can be simply realized.

[0030] In some embodiments, the semiconductor switch driving circuit may also include a first semiconductor switch driving unit and a second semiconductor switch driving unit as semiconductor switch driving units. The first semiconductor switch driving unit and the second semiconductor switch driving unit may also drive the first semiconductor switch and the second semiconductor switch as semiconductor switches, respectively. The first semiconductor switch may also constitute an upper arm in the semiconductor switch driving circuit. The second semiconductor switch may also constitute a lower arm in the semiconductor switch driving circuit, and may also be electrically connected in series with the first semiconductor switch. In this case, in both the upper arm and the lower arm, it is possible to effectively suppress the decrease in the positive voltage applied from the first capacitor to the semiconductor switch.

[0031] In some embodiments, the movement limiting portion of each of the first semiconductor switch driving unit and the second semiconductor switch driving unit may also include: a first connection point between the positive terminal of the first capacitor and the control terminal of the semiconductor switch; a second connection point between the positive terminal of the second capacitor and the input terminal of the semiconductor switch; a third connection point, which is arranged between the first connection point and the positive terminal of the driving power supply and is electrically connected to the positive terminal of the driving power supply; a first wiring, which connects the first connection point and the third connection point; and a second wiring, which connects the second connection point and the third connection point. It is also possible that only the movement limiting portion of the second semiconductor switch driving unit of the first semiconductor switch driving unit and the second semiconductor switch driving unit further includes: a first diode, which is connected in the first wiring with the direction from the third connection point toward the first connection point as the forward direction; and a second diode, which is connected in the second wiring with the direction from the third connection point toward the second connection point as the forward direction. In the upper arm, in terms of the circuit structure, it is easy for the charge to flow back to the driving power supply according to the connection or disconnection of the semiconductor switch. On the other hand, in the lower arm, it is not easy for the charge to flow back to the driving power supply regardless of whether the semiconductor switch is turned on or off in the lower arm. Therefore, in the above structure, the first diode and the second diode for preventing backflow are provided only in the first semiconductor switch driving unit constituting the upper arm, thereby simplifying the circuit structure of the second semiconductor switch driving unit and reducing the number of components constituting the second semiconductor switch driving unit.

[0032] In some embodiments, it may also include: a first semiconductor switch driving unit as a semiconductor switch driving unit, driving a first semiconductor switch as a semiconductor switch; and a second semiconductor switch driving unit, electrically connected to a driving power supply, using power from the driving power supply to drive a second semiconductor switch electrically connected in series with the first semiconductor switch. The first semiconductor switch may also constitute an upper arm in a semiconductor switch driving circuit. The second semiconductor switch may also constitute a lower arm in a semiconductor switch driving circuit. The second semiconductor switch driving unit may also include: another connection switching unit, electrically connected between the driving power supply and the second semiconductor switch, switching the connection state of the second semiconductor switch; a fourth capacitor, electrically connected between the driving power supply and the other connection switching unit, and generating a positive voltage for turning the second semiconductor switch on by charging with power from the driving power supply; and a fifth capacitor, electrically connected in series between the fourth capacitor and the other connection switching unit, and generating a negative voltage for turning the second semiconductor switch off by charging with power discharged from the fourth capacitor in a charged state. Other connection switching units can also alternately switch between a third connection state and a fourth connection state. In the third connection state, another positive voltage application closed circuit is formed by electrically connecting the positive terminal of the fourth capacitor to the control terminal of the second semiconductor switch, and another negative voltage application closed circuit is formed by electrically connecting the negative terminal of the fifth capacitor to the control terminal of the second semiconductor switch. In the fourth connection state, another negative voltage application closed circuit is formed by electrically connecting the negative terminal of the fifth capacitor to the control terminal of the second semiconductor switch. In the upper arm, the charging state of the first capacitor is switched according to the on or off of the semiconductor switch, so the voltage of the first capacitor is easy to change. On the other hand, in the lower arm, the fourth capacitor can be always in a charged state, so it is easy to maintain the voltage of the fourth capacitor constant. Therefore, in the lower arm, a simplified circuit structure is adopted by not providing a structure of the second capacitor equivalent to the upper arm, thereby reducing the number of components constituting the second semiconductor switch driving unit.

[0033] A power converter according to one embodiment of the present disclosure is a power converter that converts the form of power provided by a power source into the form of power required by a load device. The power converter includes: a semiconductor switch electrically connected between the power source and the load device; and any one of the above-mentioned semiconductor switch drive circuits electrically connected to the semiconductor switch and driving the semiconductor switch. Since the power converter includes any one of the above-mentioned semiconductor switch drive circuits, it is possible to more effectively suppress the decrease in the positive voltage applied from the first capacitor to the semiconductor switch.

[0034] [First embodiment]

[0035] Reference Figure 1, the power converter 1 involved in the first embodiment is described. The power converter 1 converts the form of electric power received from the power source 4 into the form of electric power required by the load device M. The power source 4 is a power source for driving the load device M. The load device M can be, for example, a three-phase AC motor used as a power source for rotating an impeller. Therefore, the power converter 1 can also be used as an electrical component of an electric compressor or an electric blower. The power converter 1 involved in this embodiment is, for example, an inverter that converts DC power into AC power. The power converter 1 can also be a converter that converts AC power into DC power. The power conversion device can also convert DC power in a first form into DC power in a second form.

[0036] like Figure 1 As shown, the power converter 1 includes, for example, a semiconductor switch 2 (an example of a “first semiconductor switch”), a semiconductor switch 3 (an example of a “second semiconductor switch”), a semiconductor switch drive circuit 6 , a power supply 4 , and a control device 7 .

[0037] The semiconductor switch 2 and the semiconductor switch 3 are connected in series between the power supply 4 and the GND (ground terminal) to form a switching leg. The semiconductor switch 2 forms a so-called upper arm in the semiconductor switch driving circuit 6. The semiconductor switch 3 forms a so-called lower arm in the semiconductor switch driving circuit 6. The semiconductor switch 2 and the semiconductor switch 3 are each, for example, an n-type MOSFET (metal-oxide-semiconductor field-effect transistor). The semiconductor switch 2 and the semiconductor switch 3 can also be an IGBT (Insulated Gate Bipolar Transistor), or a switch of a wide-bandgap semiconductor such as SiC (silicon carbide) or GaN (gallium nitride).

[0038] The drain terminal 2a (an example of an “input terminal”) of the semiconductor switch 2 is connected to the power supply 4. The source terminal 2b (an example of an “output terminal”) of the semiconductor switch 2 is connected to the drain terminal 3a (an example of an “input terminal”) of the semiconductor switch 3. The source terminal 3b (an example of an “output terminal”) of the semiconductor switch 3 is connected to GND. The gate terminal 2c (an example of a “control terminal”) of the semiconductor switch 2 and the gate terminal 3c (an example of a “control terminal”) of the semiconductor switch 3 are connected to the semiconductor switch drive circuit 6.

[0039] In the following description, if a certain element is “connected” to another element, it means that the certain element is “electrically connected” to the other element unless otherwise specified. “Electrically connected” means that two elements are connected in a state where signal transmission and power supply can be performed between the two elements. Therefore, “electrically connected” includes two situations where two elements are directly connected to each other through wiring and two elements are indirectly connected via other electrical elements.

[0040] The semiconductor switch driving circuit 6 drives the semiconductor switch 2 and the semiconductor switch 3. The control device 7 is electrically connected to the semiconductor switch driving circuit 6 and controls the semiconductor switch driving circuit 6. The control device 7 is composed of a computer including a CPU, a ROM, and a RAM, for example. The control device 7 controls the semiconductor switch driving circuit 6 so that the semiconductor switch 2 and the semiconductor switch 3 are alternately turned on. As a result, the input voltage Vin provided from the power supply 4 is converted into an AC voltage and supplied to the load device M.

[0041] The semiconductor switch driving circuit 6 includes, for example, a semiconductor switch driving unit 6 a (an example of a “first semiconductor switch driving circuit”), a semiconductor switch driving unit 6 b (an example of a “second semiconductor switch driving circuit”), and a driving power source 5 .

[0042] The semiconductor switch driving unit 6a is a driving circuit for driving the upper arm of the semiconductor switch 2. The semiconductor switch driving unit 6b is a driving circuit for driving the lower arm of the semiconductor switch 3. The driving power supply 5 is, for example, a DC power supply that outputs a DC voltage VDD having a positive polarity. The driving power supply 5 is electrically connected to the semiconductor switch driving unit 6a and the semiconductor switch driving unit 6b, and provides the voltage VDD to the semiconductor switch driving unit 6a and the semiconductor switch driving unit 6b. The semiconductor switch driving unit 6a switches the semiconductor switch 2 on or off using the voltage VDD. The semiconductor switch driving unit 6b switches the semiconductor switch 3 on or off using the voltage VDD.

[0043] The control device 7 is electrically connected to the semiconductor switch driving unit 6a and the semiconductor switch driving unit 6b. The control device 7 outputs control signals for controlling the driving of the semiconductor switch driving unit 6a and the semiconductor switch driving unit 6b to the semiconductor switch driving unit 6a and the semiconductor switch driving unit 6b, respectively. The control signal is, for example, a PWM (Pulse Width Modulation) signal. The control device 7 controls the switching of the semiconductor switch 2 to be turned on or off by outputting a control signal indicating the semiconductor switch 2 to the semiconductor switch driving unit 6a. When the semiconductor switch driving unit 6a receives the control signal indicating the semiconductor switch 2 to be turned on, it uses the voltage VDD to generate a positive voltage for fully turning on the semiconductor switch 2, and applies the generated positive voltage to the gate terminal 2c of the semiconductor switch 2. As a result, the semiconductor switch 2 is turned on. When the semiconductor switch driving unit 6a receives the control signal indicating the semiconductor switch 2 to be turned off, it uses the voltage VDD to generate a negative voltage for fully turning off the semiconductor switch 2, and applies the generated negative voltage to the gate terminal 2c of the semiconductor switch 2. As a result, the semiconductor switch 2 is turned off.

[0044] The control device 7 controls the switching of the semiconductor switch 3 to be turned on or off by outputting a control signal indicating the semiconductor switch 3 to the semiconductor switch driving unit 6b. When the semiconductor switch driving unit 6b receives the control signal indicating the semiconductor switch 3 to be turned on, it uses the voltage VDD to generate a positive voltage for fully turning on the semiconductor switch 3, and applies the generated positive voltage to the gate terminal 3c of the semiconductor switch 3. As a result, the semiconductor switch 3 is turned on. When the semiconductor switch driving unit 6b receives the control signal indicating the semiconductor switch 3 to be turned off, it uses the voltage VDD to generate a negative voltage for fully turning off the semiconductor switch 3, and applies the generated negative voltage to the gate terminal 3c of the semiconductor switch 3. As a result, the semiconductor switch 3 is turned off.

[0045] Hereinafter, the configurations of the semiconductor switch driving unit 6 a and the semiconductor switch driving unit 6 b will be described in more detail.

[0046] The semiconductor switch driving unit 6a has, for example, a connection switching unit 13a, a capacitor 11a (an example of a “first capacitor”), a capacitor 12a (an example of a “second capacitor”), a capacitor 16a (an example of a “third capacitor”), a diode 21a, a diode 22a, a diode 10a, a diode 14a, a diode 15a, a resistor element 31a, a resistor element 32a, a resistor element 33a, a resistor element 34a, a resistor element 35a and a resistor element 36a.

[0047] The connection switching unit 13a is connected between the driving power supply 5 and the semiconductor switch 2. The capacitor 11a is connected between the driving power supply 5 and the connection switching unit 13a. The capacitor 11a is, for example, a positive power supply capacitor that generates a positive voltage. The positive terminal 111a (one end) of the capacitor 11a is connected to the positive terminal 5a of the driving power supply 5 and the connection switching unit 13a. More specifically, the positive terminal 5a of the driving power supply 5 is connected to the wiring L2a at the connection point P1a, and the wiring L2a is connected to the positive terminal 111a of the capacitor 11a at the connection point P2a. The wiring L2a is connected to the wiring L3a at the connection point P2a, and the wiring L3a is connected to the gate terminal 2c of the semiconductor switch 2 via the connection switching unit 13a. The negative terminal 211a (the other end) of the capacitor 11a is connected to the source terminal 2b of the semiconductor switch 2 via the wiring L4a.

[0048] The capacitor 12a is, for example, a negative power buffer capacitor that temporarily stores power for generating a negative voltage. The capacitor 12a is connected between the driving power supply 5 and the semiconductor switch 2. The capacitor 12a is connected to the driving power supply 5 in parallel with the capacitor 11a. The positive terminal 112a (one end) of the capacitor 12a is connected to the positive terminal 5a of the driving power supply 5 and the drain terminal 2a of the semiconductor switch 2. More specifically, the positive terminal 5a of the driving power supply 5 is connected to the wiring L5a extending in parallel with the wiring L2a at the connection point P1a. The wiring L5a is connected to the positive terminal 112a of the capacitor 12a at the connection point P3a. The wiring L5a is connected to the wiring L6a at the connection point P3a, and the wiring L6a is connected to the drain terminal 2a of the semiconductor switch 2. The negative terminal 212a (the other end) of the capacitor 12a is connected to the drain terminal 2a of the semiconductor switch 2 via the wiring L4a.

[0049] The capacitor 16a is, for example, a negative power supply capacitor that receives power from the capacitor 12a in a charged state and generates a negative voltage. The capacitor 16a is connected between the capacitor 12a and the connection switching unit 13a. The negative terminal 216a (the other end) of the capacitor 16a is connected to the wiring L7a at the connection point P5a, and the wiring L7a is connected to the negative terminal 212a of the capacitor 12a via the connection point P6a. The positive terminal 116a (one end) of the capacitor 16a is connected to the wiring L4a at the connection point P4a, and is connected to the source terminal 2b of the semiconductor switch 2 via the wiring L4a.

[0050] The diode 21a is connected in series between the driving power supply 5 and the capacitor 11a. The diode 21a is, for example, a diode for preventing backflow. The diode 21a is connected in a wiring L2a that connects the connection point P1a connected to the positive terminal 5a of the driving power supply 5 and the connection point P2a connected to the positive terminal 111a of the capacitor 11a, with the direction from the connection point P1a to the connection point P2a as the forward direction. Therefore, the anode of the diode 21a is connected to the positive terminal 5a of the driving power supply 5, and the cathode of the diode 21a is connected to the positive terminal 111a of the capacitor 11a.

[0051] The resistor element 31a is, for example, a limiting resistor that limits the current from the driving power source 5 to the capacitor 11a. The resistor element 31a is connected in series between the diode 21a and the capacitor 11a. More specifically, the resistor element 31a is connected in series between the diode 21a and the connection point P2a in the wiring L2a. One end of the resistor element 31a is connected to the positive terminal 5a of the driving power source 5 via the diode 21a. The other end of the resistor element 31a is connected to the positive terminal 111a of the capacitor 11a.

[0052] The diode 22a is connected in series between the driving power supply 5 and the capacitor 12a. The diode 22a is, for example, a diode for preventing backflow. The diode 22a is connected in a wiring L3a connecting the connection point P1a and the connection point P3a connected to the positive terminal 112a of the capacitor 12a, with the direction from the connection point P1a to the connection point P3a as the forward direction. Therefore, the anode of the diode 22a is connected to the positive terminal 5a of the driving power supply 5. The cathode of the diode 22a is connected to the positive terminal 112a of the capacitor 12a.

[0053] The resistance element 32a is, for example, a limiting resistor that limits the current from the driving power source 5 to the capacitor 12a. The resistance element 32a is connected in series between the diode 22a and the capacitor 12a. More specifically, the resistance element 32a is connected in series between the diode 22a and the connection point P3a in the wiring L3a. One end of the resistance element 32a is connected to the positive terminal 5a of the driving power source 5 via the diode 22a. The other end of the resistance element 32a is connected to the positive terminal 112a of the capacitor 12a. The resistance element 32a has, for example, a resistance value different from the resistance value of the resistance element 31a. The resistance value of the resistance element 32a may be higher than the resistance value of the resistance element 31a.

[0054] The resistor element 33a is connected in series between the positive terminal 112a of the capacitor 12a and the connection point P3a. The resistor element 33a is a limiting resistor that limits the current from the drive power supply 5 to the capacitor 12a and the current from the capacitor 12a to the capacitor 16a. One end of the resistor element 33a is connected to the positive terminal 5a of the drive power supply 5 via the resistor element 32a and the diode 22a. One end of the resistor element 33a is connected to the positive terminal 116a of the capacitor 16a via the semiconductor switch 2. The other end of the resistor element 33a is connected to the positive terminal 112a of the capacitor 12a.

[0055] The diode 10a is connected in series between the connection point P3a and the drain terminal 2a of the semiconductor switch 2. The diode 10a is, for example, a diode for preventing backflow. The diode 10a is connected in the wiring L6a between the connection point P3a and the drain terminal 2a of the semiconductor switch 2, with the direction from the connection point P3a to the drain terminal 2a being the forward direction. As a result, the diode 10a is connected in series with the diode 22a and the resistor 32a. The diode 10a is connected in series with the semiconductor switch 2 and the capacitor 16a. Therefore, the anode of the diode 10a is connected to the positive terminal 5a of the driving power supply 5 via the diode 22a and the resistor 32a. The cathode of the diode 10a is connected to the positive terminal 116a of the capacitor 16a via the semiconductor switch 2.

[0056] The resistor element 34a is connected in series between the diode 10a and the drain terminal 2a of the semiconductor switch 2. The resistor element 34a is, for example, a limiting resistor that limits the current from the capacitor 12a to the capacitor 16a. One end of the resistor element 34a is connected to the positive terminal 5a of the drive power supply 5 via the diode 10a, the resistor element 32a, and the diode 22a. The other end of the resistor element 34a is connected to the positive terminal 116a of the capacitor 16a via the semiconductor switch 2.

[0057] The diode 14a is connected in series between the connection point P5a and the connection point P6a. The diode 14a is, for example, a diode for rectification. The diode 14a is connected in the wiring L7a between the connection point P5a and the connection point P6a, with the direction from the connection point P5a to the connection point P6a as the forward direction. The anode of the diode 14a is connected to the connection switching unit 13a and the negative terminal 216a of the capacitor 16a via the connection point P5a. The cathode of the diode 14a is connected to the negative terminal 212a of the capacitor 12a via the connection point P6a.

[0058] The resistor element 35a is connected in series between the diode 14a and the connection point P6a. The resistor element 35a is, for example, a limiting resistor that limits the current from the capacitor 12a to the capacitor 16a. One end of the resistor element 35a is connected to the negative terminal 212a of the capacitor 12a via the connection point P6a. The other end of the resistor element 35a is connected to the negative terminal 216a of the capacitor 16a via the diode 14a and the connection point P5a.

[0059] The diode 15a is directly connected between the connection point P6a and the wiring L4a, and is connected in parallel with the capacitor 16a. The diode 15a is connected with the direction from the connection point P6a to the wiring L4a as the forward direction. The diode 15a is, for example, a voltage limiting diode that limits the voltage across the capacitor 16a to a predetermined voltage. The predetermined voltage is, for example, a negative voltage applied to the gate terminal 2c of the semiconductor switch 2 as a gate voltage. This voltage is set based on the withstand voltage of the gate terminal 2c of the semiconductor switch 2, for example.

[0060] The resistor element 36a is connected in series between the diode 10a and the wiring L4a. The resistor element 36a is, for example, a limiting resistor that limits the current from the drive power supply 5 to the capacitor 12a. One end of the resistor element 36a is connected to the negative terminal 211a of the capacitor 12a via the diode 15a. The other end of the resistor element 36a is connected to the wiring L4a.

[0061] The connection switching unit 13a includes a switch 131a and a switch 132a connected in series with each other. For example, the switch 131a is an NPN-type IGBT, and the switch 132a is a PNP-type IGBT. The switch 131a and the switch 132a constitute a so-called push-pull circuit. The collector terminal of the switch 131a is connected to the positive terminal 111a of the capacitor 11a. The emitter terminal of the switch 131a is connected to the emitter terminal of the switch 132a. The connection point between the emitter terminal of the switch 131a and the emitter terminal of the switch 132a is connected to the gate terminal 2c of the semiconductor switch 2. The collector terminal of the switch 132a is connected to the negative terminal 216a of the capacitor 16a. The base terminal of the switch 131a and the base terminal of the switch 132a are connected to the control device 7 to receive the control signal from the control device 7.

[0062] When the connection switching unit 13a receives a control signal instructing the semiconductor switch 2 to be turned on, it is controlled to a first connection state in which the switch 131a is turned on and the switch 132a is turned off. In the first connection state, a positive voltage application closed circuit C14 that applies the positive voltage of the capacitor 11a to the gate terminal 2c of the semiconductor switch 2 and a negative voltage charging closed circuit C15 that charges the capacitor 16a with a negative voltage are formed (see Figure 3 ).

[0063] Positive voltage is applied to close circuit C14 by Figure 3 The positive voltage application closed circuit C14 is formed by connecting the positive terminal 111a of the capacitor 11a to the gate terminal 2c of the semiconductor switch 2 via the switch 131a in the on state. The positive voltage application closed circuit C14 includes, for example, a capacitor 11a, a switch 131a, and a semiconductor switch 2. In the positive voltage application closed circuit C14, the charge charged to the capacitor 11a is supplied to the semiconductor switch 2 via the switch 131a. As a result, the input capacitance of the semiconductor switch 2 starts to be charged by the charge discharged from the capacitor 11a. Thereafter, by charging a certain amount of charge to the input capacitance of the semiconductor switch 2, the semiconductor switch 2 is turned on. In the present embodiment, a resistance element is not included in the positive voltage application closed circuit C14.

[0064] The negative voltage charging closed circuit C15 is Figure 3 The negative voltage charging closed circuit C15 is formed by connecting the positive terminal 112a of the capacitor 12a to the positive terminal 116a of the capacitor 16a via the switch 131a in the on state. The negative voltage charging closed circuit C15 includes, for example, a capacitor 12a, a resistor 33a, a diode 10a, a resistor 34a, a semiconductor switch 2, a capacitor 16a, a diode 14a, and a resistor 35a. In the negative voltage charging closed circuit C15, the charge charged to the capacitor 12a is supplied to the capacitor 16a via the resistor 33a, the diode 10a, the resistor 34a, and the semiconductor switch 2. The capacitor 16a is charged by the charge from the capacitor 12a. At this time, the positive terminal 116a of the capacitor 16a is charged with a positive charge, and the negative terminal 216a of the capacitor 16a is charged with a negative charge. As a result, a negative voltage is generated in the capacitor 16a.

[0065] In the negative voltage charging closed circuit C15, the charge charged to the capacitor 12a flows through the resistor 33a, the resistor 34a, and the resistor 35a. Therefore, the resistor 33a, the resistor 34a, and the resistor 35a have the function of limiting the charging current from the capacitor 12a to the capacitor 16a. Therefore, by adjusting the combined resistance value of the resistor 33a, the resistor 34a, and the resistor 35a, the charging current to the capacitor 16a can be adjusted.

[0066] When the connection switching unit 13a receives a control signal instructing the semiconductor switch 2 to be disconnected, it is controlled to be in a second connection state in which the switch 131a is turned off and the switch 132a is turned on. In the second connection state, a negative voltage applying closed circuit C13 for applying the negative voltage of the capacitor 16a to the gate terminal 2c of the semiconductor switch 2, a positive voltage charging closed circuit C11 for charging the capacitor 11a with a positive voltage, and a temporary charging closed circuit C12 for temporarily charging the capacitor 12a with power for generating a negative voltage are formed (see Figure 2 ).

[0067] Negative voltage is applied to close circuit C13 by Figure 2 A closed circuit of the path W13 of the negative voltage application closed circuit C13. The negative voltage application closed circuit C13 is formed by connecting the negative terminal 216a of the capacitor 16a to the gate terminal 2c of the semiconductor switch 2 via the switch 132a in the on state. The negative voltage application closed circuit C13 includes, for example, a capacitor 16a, a switch 132a, and a semiconductor switch 2. In the negative voltage application closed circuit C13, the charge charged to the capacitor 16a is supplied to the semiconductor switch 2 via the switch 132a. As a result, a positive voltage is applied to the semiconductor switch 2, and the semiconductor switch 2 is turned on. In this case, by discharging the charge charged to the input capacitor of the semiconductor switch 2, the semiconductor switch 2 moves from the on state to the off state. In other words, the negative charge charged to the capacitor 16a is supplied to the gate terminal 2c of the semiconductor switch 2, thereby applying a negative voltage to the gate terminal 2c of the semiconductor switch 2. As a result, the semiconductor switch 2 is turned off.

[0068] The positive voltage charging closed circuit C11 is Figure 2 A closed circuit of the path W11. It is formed by connecting the negative terminal 211a of the capacitor 11a to the negative terminal 5b of the driving power supply 5 via the semiconductor switch 3 in the on state. The positive voltage charging closed circuit C11 includes, for example, the driving power supply 5, the diode 21a, the resistor 31a, the capacitor 11a and the semiconductor switch 3. In the positive voltage charging closed circuit C11, the capacitor 11a is charged by the voltage VDD from the driving power supply 5. In the positive voltage charging closed circuit C11, the charge from the driving power supply 5 flows in a manner via the resistor 31a. Therefore, the resistor 31a has a function of limiting the charging current from the driving power supply 5 to the capacitor 11a. Therefore, by adjusting the resistance value of the resistor 31a, the charging current to the capacitor 11a can be adjusted.

[0069] Temporarily charging the closed circuit C12 is done by Figure 2The temporary charging closed circuit C12 is formed by connecting the negative terminal 212a of the capacitor 12a to the negative terminal 5b of the driving power supply 5 via the semiconductor switch 3 in the on state. The temporary charging closed circuit C12 includes, for example, the driving power supply 5, the diode 22a, the resistor 32a, the capacitor 12a, and the semiconductor switch 3. In the temporary charging closed circuit C12, the capacitor 12a is charged by the voltage VDD from the driving power supply 5. In the temporary charging closed circuit C12, the charge from the driving power supply 5 flows in a manner via the resistor 32a, the resistor 33a, and the resistor 36a. Therefore, the resistor 32a, the resistor 33a, and the resistor 36a have a function of limiting the charging current from the driving power supply 5 to the capacitor 12a. Therefore, by adjusting the combined resistance value of the resistor 32a, the resistor 33a, and the resistor 36a, the charging current to the capacitor 12a can be adjusted. The resistance element 33a has both the function of adjusting the charging current to the capacitor 12a and the above-mentioned function of adjusting the charging current to the capacitor 16a.

[0070] In this way, the connection switching unit 13a alternately switches between a first connection state in which the positive voltage application closed circuit C14 and the negative voltage charging closed circuit C15 are formed, and a second connection state in which the negative voltage application closed circuit C13, the positive voltage charging closed circuit C11, and the temporary charging closed circuit C12 are formed, according to the control signal. In the first connection state, a positive voltage for turning on the semiconductor switch 2 is applied to the gate terminal 2c of the semiconductor switch 2 through the positive voltage application closed circuit C14. In the second connection state, a negative voltage for turning off the semiconductor switch 2 is applied to the gate terminal 2c of the semiconductor switch 2 through the negative voltage application closed circuit C13. Therefore, by alternately switching between the first connection state and the second connection state, the connection and disconnection of the semiconductor switch 2 can be alternately switched.

[0071] In the semiconductor switch driving unit 6a according to the present embodiment, a movement restricting unit 50a (see Figure 1), the movement limiting portion 50a limits the movement of the charge from the path W14 passing through the positive voltage application closed circuit C14 to other paths passing through the positive terminal 111a of the capacitor 11a and not passing through the gate terminal 2c of the semiconductor switch 2. The movement limiting portion 50a is provided between the positive terminal 111a of the capacitor 11a and the drain terminal 2a of the semiconductor switch 2. The movement limiting portion 50a adjusts the movement path of the charge of the capacitor 11a so as to prevent the charge of the capacitor 11a from moving from the path W14 passing through the positive voltage application closed circuit C14 to a path other than the path W14. The “other path” may be any path that passes through the positive terminal 111a of the capacitor 11a and does not pass through the gate terminal 2c of the semiconductor switch 2, or any path other than the path W14 that passes through the positive terminal 111a of the capacitor 11a and passes through the gate terminal 2c of the semiconductor switch 2. For example, the “other path” may be a path returning from the positive terminal 111 a of the capacitor 11 a through the drain terminal 2 a of the semiconductor switch 2 to the positive terminal 111 a of the capacitor 11 a .

[0072] The movement limiting portion 50a includes, for example, a connection point P1a (an example of a "third connection point"), a connection point P2a (an example of a "first connection point"), a connection point P3a (an example of a "second connection point"), a wiring L2a (an example of a "first wiring"), a wiring L5a (an example of a "second wiring"), a diode 21a (an example of a "first diode"), a diode 22a (an example of a "second diode"), a resistor 31a (an example of a "first resistor"), and a resistor 32a (an example of a "second resistor"). The connection point P1a is a branch point from the wiring connected to the positive terminal 5a of the driving power source 5 to the wiring L2a and the wiring L5a. The connection point P1a is located on the wiring between the positive terminal 5a of the driving power source 5 and the positive terminal 111a of the capacitor 11a, and is located closer to the driving power source 5 than the connection point P2a. The wiring L2a connecting the connection point P1a and the connection point P2a is connected to the wiring L3a constituting the positive voltage applying closed circuit C14 at the connection point P2a.

[0073] The connection point P3a is located on the wiring between the positive terminal 5a of the driving power source 5 and the positive terminal 112a of the capacitor 12a, and is located closer to the driving power source 5 than the connection point P5a. The wiring L5a connecting the connection point P1a and the connection point P3a is connected to the wiring L6a at the connection point P3a. The connection point P2a is not directly connected to the wiring L5a and the wiring L6a. Therefore, downstream of the connection point P1a which is the branch point between the wiring L2a and the wiring L5a, the wiring L2a and the wiring L3a are independent of the wiring L5a and the wiring L6a, and do not have a connection point with the wiring L5a and the wiring L6a.

[0074] In this case, the paths through which the charge charged to the capacitor 11a in the first connection state can move are limited to a path from the positive terminal 111a of the capacitor 11a to the wiring L3a via the connection point P2a and a path from the positive terminal 111a of the capacitor 11a to the wiring L2a via the connection point P2a. Here, since the diode 21a for preventing backflow is provided in the wiring L2a, the movement of the charge from the connection point P2a to the connection point P1a is restricted. Therefore, the path through which the charge moves from the connection point P2a to the connection point P3a is excluded.

[0075] As a result, in the first connection state, the charge of the capacitor 11a is prevented from moving from the path W14 of the positive voltage application closed circuit C14 to other paths, such as the path where the charge of the capacitor 11a moves through the connection point P3a and via the capacitor 12a, or the path where the charge of the capacitor 11a moves through the connection point P3a and via the drain terminal 2a of the semiconductor switch 2. Therefore, in the first connection state, the charge of the capacitor 11a moves only on the path W14 that passes through the wiring L3a and via the gate terminal 2c of the semiconductor switch 2. In this way, in the present embodiment, the movement restriction portion 50a prevents the charge of the capacitor 11a from moving from the path W14 of the positive voltage application closed circuit C14 to other paths in the first connection state.

[0076] The semiconductor switch driving unit 6b has the same structure as the semiconductor switch driving unit 6a except that it does not have circuit elements corresponding to the diodes 21a and 22a. When the parts of the reference numerals attached to the structures of the semiconductor switch driving unit 6b except for the suffix "b" are the same as the parts of the reference numerals attached to the structures of the semiconductor switch driving unit 6a except for the suffix "a", it means that the structures indicated by these reference numerals are the same. Therefore, the detailed description of each structure of the semiconductor switch driving unit 6b is omitted because it overlaps with the description of each structure of the semiconductor switch driving unit 6a.

[0077] The semiconductor switch driving unit 6b constituting the lower arm is different from the semiconductor switch driving unit 6a constituting the upper arm. In terms of voltage balance, it is assumed that the charge does not flow back to the driving power supply 5, so the circuit elements corresponding to the diode 21a and the diode 22a can be omitted. Usually, the voltage VDD (e.g., 15V) of the driving power supply 5 for driving the semiconductor switch 2 and the semiconductor switch 3 is lower than the input voltage Vin (e.g., 300V) of the power supply 4 for driving the load device M.

[0078] In the first connection state (i.e., when the semiconductor switch 2 is in the on state and the semiconductor switch 3 is in the off state), the negative terminal 211a of the capacitor 11a is connected to the power supply 4 via the semiconductor switch 2. Therefore, a relatively high input voltage Vin is applied to the negative terminal 211a of the capacitor 11a. On the other hand, the positive terminal 111a of the capacitor 11a is connected to the positive terminal 5a of the driving power supply 5. Therefore, a relatively low voltage VDD is applied to the positive terminal 111a of the capacitor 11a. As a result, in the upper arm, due to the voltage difference between these input voltages Vin and voltage VDD, a current may flow back from the power supply 4 to the driving power supply 5. Therefore, in order to prevent such a backflow, it is necessary to provide diodes 21a and 22a.

[0079] On the other hand, in the lower arm, the reverse flow from the power supply 4 to the driving power supply 5 is prevented by the diode 10b, and the voltage VDD of the power supply 4 will not be applied to the capacitor 11a, etc. Moreover, the negative terminal 5b of the driving power supply 5, etc. is always applied with the GND potential. Therefore, in the lower arm, the current will not flow back from the power supply 4 to the driving power supply 5 due to the voltage difference between the input voltage Vin and the voltage VDD. Therefore, it is not necessary to set circuit elements corresponding to the diodes 21a and 22a. However, the semiconductor switch driving unit 6b of the lower arm can also have circuit elements corresponding to the diodes 21a and 22a, just like the semiconductor switch driving unit 6a of the upper arm. In this case, these circuit elements can be used as a backup in the event that the diode 10b is damaged. The semiconductor switch driving unit 6b can also have a structure different from the semiconductor switch driving unit 6a in addition to the diodes 21a and 22a.

[0080] [Operation of semiconductor switch drive circuit]

[0081] Next, the operation flow of the semiconductor switch driving circuit 6 is described. In the present embodiment, the semiconductor switch driving circuit 6 has: a first operation mode, in which the connection switching unit 13a of the semiconductor switch driving unit 6a is set to the second connection state, and the connection switching unit 13b of the semiconductor switch driving unit 6b is set to the first connection state; and a second operation mode, in which the connection switching unit 13a of the semiconductor switch driving unit 6a is set to the first connection state, and the connection switching unit 13b of the semiconductor switch driving unit 6b is set to the second connection state. The semiconductor switch driving circuit 6 alternately switches between the first operation mode and the second operation mode according to the control signal from the control device 7, thereby driving the semiconductor switch 2 and the semiconductor switch 3 to alternately become the on state.

[0082] First, refer to Figure 2 and Figure 3 , the operation of the semiconductor switch driving unit 6a for switching the semiconductor switch 2 on or off will be described. Figure 2 and Figure 3 In FIG. 1 , the semiconductor switch 2, the semiconductor switch 3, the switch 131a, the switch 132a, the switch 131b, and the switch 132b shown by the dotted line are turned off. The semiconductor switch 2, the semiconductor switch 3, the switch 131a, the switch 132a, the switch 131b, and the switch 132b shown by the solid line are turned on. Before the first operation mode is implemented, the charge is charged to the capacitor 16a.

[0083] <First action mode>

[0084] In the first operation mode, since the connection switching unit 13a is in the second connection state, Figure 2 As shown, a negative voltage application closed circuit C13 is formed by connecting the capacitor 16a and the semiconductor switch 2. In the negative voltage application closed circuit C13, the charge charged to the capacitor 16a returns to the capacitor 16a through the path W13 via the semiconductor switch 2. The negative voltage of the capacitor 16a is supplied to the gate terminal 2c of the semiconductor switch 2, thereby the semiconductor switch 2 is turned off.

[0085] In the first operation mode, a positive voltage charging closed circuit C11 is formed by connecting the capacitor 11a to the driving power supply 5. In the positive voltage charging closed circuit C11, the current from the driving power supply 5 flows through the path W11 that returns to the driving power supply 5 via the capacitor 11a and the semiconductor switch 3. The capacitor 11a is charged by this current. In the first operation mode, a temporary charging closed circuit C12 is formed by connecting the capacitor 12a to the driving power supply 5. In the temporary charging closed circuit C12, the current from the driving power supply 5 flows through the path W12 that returns to the driving power supply 5 via the capacitor 12a and the semiconductor switch 3. The capacitor 12a is charged by this current.

[0086] <Second operation mode>

[0087] In the second operation mode, since the connection switching unit 13a is in the first connection state, Figure 3 As shown, a positive voltage application closed circuit C14 is formed by connecting the capacitor 11a and the semiconductor switch 2. In the positive voltage application closed circuit C14, the charge charged to the capacitor 11a returns to the capacitor 11a through a path W14 via the semiconductor switch 2. The positive charge of the capacitor 11a is supplied to the gate terminal 2c of the semiconductor switch 2, whereby the semiconductor switch 2 is moved from the off state to the on state.

[0088] In the second operation mode, the capacitor 12a and the capacitor 16a are connected to form a negative voltage charging closed circuit C15. In the negative voltage charging closed circuit C15, the charge charged to the capacitor 12a flows through the path W15 returning to the capacitor 12a via the semiconductor switch 2 and the capacitor 16a. Thus, the capacitor 16a is charged.

[0089] Next, refer to Figure 4 and Figure 5 , the operation of the semiconductor switch driving unit 6b for switching the semiconductor switch 3 on or off will be described. Figure 4 and Figure 5 In FIG. 1 , the semiconductor switch 2, the semiconductor switch 3, the switch 131a, the switch 132a, the switch 131b, and the switch 132b shown by the dotted line are disconnected, and the semiconductor switch 2, the semiconductor switch 3, the switch 131a, the switch 132a, the switch 131b, and the switch 132b shown by the solid line are connected. Before the first operation mode is implemented, the charge is charged to the capacitor 16a.

[0090] <First action mode>

[0091] In the first operation mode, since the connection switching unit 13b of the semiconductor switch driving unit 6b is in the first connection state, Figure 4 As shown, a positive voltage application closed circuit C24 is formed by connecting the capacitor 11b and the semiconductor switch 3. In the positive voltage application closed circuit C24, the charge charged to the capacitor 11b returns to the capacitor 11b through the path W24 via the semiconductor switch 3. The positive charge of the capacitor 11b is supplied to the gate terminal 2c of the semiconductor switch 3, thereby turning the semiconductor switch 3 into an on state.

[0092] In the first operation mode, the capacitor 12b and the capacitor 16b are connected to form a negative voltage charging closed circuit C25. In the negative voltage charging closed circuit C25, the charge charged to the capacitor 12b flows through the path W25 returning to the capacitor 12b via the semiconductor switch 3 and the capacitor 16b. Thus, the capacitor 16b is charged.

[0093] <Second operation mode>

[0094] In the second operation mode, since the connection switching unit 13b of the semiconductor switch driving unit 6b is in the second connection state, Figure 5As shown, a negative voltage application closed circuit C23 is formed by connecting the capacitor 16b and the semiconductor switch 3. In the negative voltage application closed circuit C23, the charge charged to the capacitor 16b returns to the capacitor 16b through the path W23 via the semiconductor switch 3. The negative charge of the capacitor 16b is supplied to the gate terminal 2c of the semiconductor switch 3, thereby the semiconductor switch 3 is turned off.

[0095] In the second operation mode, a positive voltage charging closed circuit C21 is formed by connecting the capacitor 11b to the driving power supply 5. In the positive voltage charging closed circuit C21, the current from the driving power supply 5 flows through the path W21 that returns to the driving power supply 5 via the capacitor 11b and the semiconductor switch 3. The capacitor 11b is charged by this current. In the first operation mode, a temporary charging closed circuit C22 is formed by connecting the capacitor 12b to the driving power supply 5. In the temporary charging closed circuit C22, the current from the driving power supply 5 flows through the path W22 that returns to the driving power supply 5 via the capacitor 12b and the semiconductor switch 3. The capacitor 12b is charged by this current.

[0096] [Effects]

[0097] Next, the effects achieved by the semiconductor switch drive circuit 6 and the power converter 1 according to the present embodiment will be described together with the problems of the comparative example.

[0098] Fig.12 2 shows a driving circuit 206 for the upper arm of the power converter 100 according to the comparative example. The driving circuit 206 does not include the movement restriction portion 50a, unlike the semiconductor switch driving portion 6a according to the present embodiment. In this case, in the first connection state, the charge charged in the capacitor 101 not only returns to the capacitor 101 via the gate terminal 2c of the semiconductor switch 2 through the path W110, but also moves from the connection point P101 to the connection point P102 and passes through the path W120 of the capacitor 102 and moves from the connection point P101 to the connection point P102 and passes through the drain terminal 2a of the semiconductor switch 2. Path W130.

[0099] In this way, since the charge of the capacitor 101 passes through the path W120 passing through the gate terminal 2c of the semiconductor switch 2, when it moves to the other path W120 or path W130 passing through the capacitor 101 and the gate terminal 2c of the semiconductor switch 2, the positive voltage of the capacitor 101 is divided to the semiconductor switch 2 and other circuit elements, and the problem of reducing the positive voltage applied to the semiconductor switch 2 occurs. For example, in the path W120, the positive voltage of the capacitor 101 is divided to the resistor 105, the capacitor 102, and the semiconductor switch 2. In the path W130, the positive voltage of the capacitor 101 is divided to the resistor 105 and the semiconductor switch 2. In particular, in the path W130, the charge of the capacitor 101 does not contribute to the charging of the capacitor 102, but passes through a path where it is consumed in the resistor 105 and returns to the capacitor 101, so the power of the capacitor 101 is consumed unnecessarily.

[0100] In contrast, in the present embodiment, a movement limiting portion 50a is provided to limit the movement of the charge of the capacitor 11a from the path W14 of the positive voltage application closed circuit C14 to other paths. Thus, it is possible to prevent the charge of the capacitor 11a from passing through other paths such as the path W120 and the path W130, and thus it is possible to prevent the positive voltage of the capacitor 11a from being divided to the circuit elements on other paths. Thus, it is possible to effectively suppress the reduction of the positive voltage applied from the capacitor 11a to the semiconductor switch 2. Thus, when the semiconductor switch driving circuit 6 turns on the semiconductor switch 2, it is possible to supply sufficient charge to the gate terminal 2c of the semiconductor switch 2. That is, the semiconductor switch driving circuit 6 can reliably control the semiconductor switch 2 to be turned on.

[0101] In the present embodiment, a capacitor 12a is provided for charging the capacitor 16a. Thus, it is not necessary to configure the capacitor 16a on the positive voltage application closed circuit C14 that applies the positive voltage of the capacitor 11a to the control terminal of the semiconductor switch 2 for charging the capacitor 16a. That is, the path W14 for the charge movement of the capacitor 11a in the positive voltage application closed circuit C14 becomes a path that does not pass through the capacitor 16a. Thus, the situation where the positive voltage of the capacitor 11a is divided to the semiconductor switch 2 and the capacitor 16a is avoided. In the present embodiment, the path W11 for the charge movement of the capacitor 11a in the positive voltage charging closed circuit C11 and the path W12 for the charge movement of the capacitor 12a in the temporary charging closed circuit C12 are both paths that do not pass through the capacitor 16a. Thus, the voltage VDD of the driving power supply 5 is applied to the capacitor 11a without being divided by the capacitor 16a. Similarly, the voltage VDD of the driving power supply 5 is applied to the capacitor 11a without being divided by the capacitor 16a.

[0102] Therefore, in this embodiment, the decrease in the positive voltage applied to the semiconductor switch 2 is effectively suppressed. In this embodiment, a positive voltage is generated in the capacitor 11a by the power from the driving power supply 5, and a negative voltage is generated in the capacitor 16a by the power discharged from the charged capacitor 12a. That is, a positive voltage and a negative voltage are generated using one driving power supply 5. As a result, there is no need to separately provide a driving power supply 5 for generating a negative voltage, so that the size and weight of the device structure can be suppressed.

[0103] As in the present embodiment, the movement limiting portion 50a may also include a connection point P2a between the positive terminal 111a of the capacitor 11a and the gate terminal 2c of the semiconductor switch 2, a connection point P3a between the positive terminal 112a of the capacitor 12a and the drain terminal 2a of the semiconductor switch 2, a connection point P1a between the connection point P2a and the positive terminal 5a of the driving power source 5, a wiring L2a connecting the connection point P2a and the connection point P1a, and a wiring L5a connecting the connection point P3a and the connection point P1a. In this way, when the connection point P1a is provided between the connection point P2a and the driving power source 5, it is possible to allow the charge to move from the driving power source 5 to the capacitor 11a via the connection point P1a and the connection point P2a, and prevent the charge released from the capacitor 11a from moving to the connection point P3a via the connection point P2a and the connection point P1a. Thus, the charge of the capacitor 11a moving in the path W14 of the positive voltage application closed circuit C14 can be prevented from moving from the connection point P2a to other paths via the connection point P3a. As a result, the positive voltage of the capacitor 11a can be more effectively suppressed from being divided to other circuit elements, and the positive voltage applied to the semiconductor switch 2 can be more effectively suppressed from being reduced.

[0104] As in the present embodiment, the movement limiting portion 50a may also include: a diode 21a, which is connected in the wiring L2a in the direction from the connection point P1a to the connection point P2a as a forward direction; and a diode 22a, which is connected in the wiring L5a in the direction from the connection point P1a to the connection point P3a as a forward direction. By providing the diodes 21a and 22a in this way, it is possible to avoid the situation where the charge from the capacitor 11a and the capacitor 12a flows back to the driving power supply 5. In addition, by providing the diode 21a between the connection point P1a and the connection point P2a, it is possible to avoid the situation where the charge of the capacitor 11a moves from the connection point P2a to the connection point P3a via the connection point P1a. As a result, it is possible to more effectively suppress the situation where the positive voltage of the capacitor 11a is divided to other circuit elements. As a result, it is possible to avoid the charge of the capacitor 11a from moving to other paths via the connection point P3a, so it is possible to more effectively suppress the situation where the positive voltage applied from the capacitor 11a to the semiconductor switch 2 is reduced.

[0105] As in the present embodiment, the movement limiting portion 50a may also include: a resistor element 31a, which is connected in series with the diode 21a in the wiring L2a; and a resistor element 32a, which is connected in series with the diode 22a in the wiring L5a and has a higher resistance value than the resistor element 31a. The negative voltage for turning the semiconductor switch 2 into an off state tends to be smaller than the positive voltage for turning the semiconductor switch 2 into an on state. In this way, when the negative voltage is small, the charge amount of the capacitor 12a for charging the power for generating the negative voltage can be smaller than the charge amount of the capacitor 11a for charging the power for generating the positive voltage. Therefore, in the above structure, the resistor element 32a provided on the moving path of the charge flowing from the driving power source 5 to the capacitor 12a has a higher resistance value than the resistance value of the resistor element 31a provided on the moving path of the charge flowing from the driving power source 5 to the capacitor 11a. As a result, the charging current supplied from the driving power source 5 to the capacitor 12a can be suppressed to be small. As a result, it is possible to suppress an increase in the capacity of the driving power source 5 that supplies electric power to the capacitor 12 a.

[0106] As in the present embodiment, the positive terminal 111a of the capacitor 11a may be connected to the positive terminal 5a of the driving power source 5 and the gate terminal 2c of the semiconductor switch 2. The positive terminal 112a of the capacitor 12a may be connected to the positive terminal 5a of the driving power source 5. The negative terminal 216a of the capacitor 16a may be connected to the negative terminal 212a of the capacitor 12a. The positive terminal 116a of the capacitor 16a may be connected to the gate terminal 2c of the semiconductor switch 2. In this case, a structure in which a positive voltage and a negative voltage are generated using one driving power source 5 can be easily realized.

[0107] As in the present embodiment, the semiconductor switch driving unit 6a and the semiconductor switch driving unit 6b may include the movement restricting unit 50a and the movement restricting unit 50b, respectively. In this case, the positive voltage applied to the semiconductor switch 2 and the semiconductor switch 3 can be effectively suppressed from decreasing in both the upper arm and the lower arm.

[0108] As in the present embodiment, the semiconductor switch driving unit 6b may also have the same structure as the semiconductor switch driving unit 6a except that it does not have circuit elements corresponding to the diodes 21a and 22a. As described above, in the upper arm, depending on whether the semiconductor switch 2 is turned on or off, charges sometimes flow back to the driving power supply 5. On the other hand, in the lower arm, no matter whether the semiconductor switch 3 is turned on or off, there is no situation where charges flow back to the driving power supply 5. Therefore, in the present embodiment, the semiconductor switch driving unit 6a constituting the upper arm is provided with the diodes 21a and 22a, and the semiconductor switch driving unit 6b constituting the lower arm is not provided with circuit elements corresponding to the diodes 21a and 22a. As a result, the number of components constituting the semiconductor switch driving unit 6b can be reduced.

[0109] The semiconductor switch driving circuit 6 is not limited to the above circuit structure, and may also have other circuit structures. Figure 6 The power converter 1A shown in the figure may include a semiconductor switch drive circuit 6A having a different arrangement of resistor elements instead of the semiconductor switch drive circuit 6. The semiconductor switch drive unit 6aa (an example of a "first semiconductor switch drive unit") of the semiconductor switch drive circuit 6A includes resistor elements 41a, 42a, 43a, and 44a instead of the resistor elements 31a, 32a, 33a, 34a, 35a, and 36a.

[0110] The resistance element 41a is connected in series between the positive terminal 111a of the capacitor 11a and the connection point P2a. The resistance element 41a is, for example, a limiting resistor that limits the charging current from the drive power supply 5 to the capacitor 11a and the gate current (positive voltage) from the capacitor 11a to the semiconductor switch 2. The resistance element 42a is connected in series between the negative terminal 211a of the capacitor 11a and the connection point P4a. The resistance element 42a is, for example, a limiting resistor that limits the charging current from the drive power supply 5 to the capacitor 11a, the charging current from the drive power supply 5 to the capacitor 12a, and the gate current (positive voltage) from the capacitor 11a to the semiconductor switch 2.

[0111] The resistor element 43a is connected in series between the positive terminal 116a of the capacitor 16a and the connection point P4a. The resistor element 43a is, for example, a limiting resistor that limits the charging current from the capacitor 12a to the capacitor 16a and the gate current (negative voltage) from the capacitor 16a to the semiconductor switch 2. The resistor element 44a is connected in series between the connection point P4a and the source terminal 2b of the semiconductor switch 2. The resistor element 44a is, for example, a limiting resistor that limits the charging current from the drive power supply 5 to the capacitor 11a, the charging current from the drive power supply 5 to the capacitor 12a, the charging current from the capacitor 12a to the capacitor 16a, and the gate current (negative voltage) from the capacitor 16a to the semiconductor switch 2.

[0112] The semiconductor switch driving unit 6bb (an example of the "second semiconductor switch driving unit") of the semiconductor switch driving circuit 6A includes a resistor element 41b, a resistor element 42b, a resistor element 43b, and a resistor element 44b corresponding to the resistor element 41a, the resistor element 42a, the resistor element 43a, and the resistor element 44a, respectively. Even the semiconductor switch driving circuit 6A having such a circuit structure can achieve the same effect as the above effect.

[0113] [Second embodiment]

[0114] Next, the second embodiment will be described. In the following description of the second embodiment, descriptions of portions overlapping with the first embodiment will be appropriately omitted, and portions different from the first embodiment will be mainly described.

[0115] like Figure 7 As shown, the power converter 1B according to the second embodiment includes a semiconductor switch drive circuit 6B instead of the semiconductor switch drive circuit 6. The semiconductor switch drive circuit 6B is different from the semiconductor switch drive circuit 6 in that it includes a semiconductor switch drive unit 6c instead of the semiconductor switch drive unit 6b. The semiconductor switch drive unit 6c includes, for example, a connection switching unit 13c (an example of an “other connection switching unit”), a capacitor 11c (an example of a “fourth capacitor”), a capacitor 16c (an example of a “fifth capacitor”), and a resistor 51c.

[0116] The capacitor 11c is connected between the driving power supply 5 and the connection switching unit 13c. The capacitor 11c is, for example, a positive power supply capacitor that generates a positive voltage. The positive terminal 111c (one end) of the capacitor 11c is connected to the positive terminal 5a of the driving power supply 5 via the wiring L2c. The positive terminal 111c of the capacitor 11c is connected to the connection switching unit 13c via the wiring L4c. The negative terminal 211c (the other end) of the capacitor 11c is connected to the negative terminal 5b of the driving power supply 5 via the wiring L3c. The negative terminal 211c of the capacitor 11c is connected to the connection switching unit 13c via the wiring L5c.

[0117] Capacitor 16c is a negative power supply capacitor that generates a negative voltage by receiving power from capacitor 12c in a charged state. Capacitor 16c is connected in series with capacitor 11c between connection point P2c of wiring L2c and wiring L4c and connection point P3c of wiring L3c and wiring L5c. Capacitor 16c is connected between capacitor 11c and connection point P3c. Negative terminal 216c (the other end) of capacitor 16c is connected to negative terminal 211c of capacitor 11c. Positive terminal 116c (one end) of capacitor 16c is connected to connection point P3c. Connection point P4c between negative terminal 216c of capacitor 16c and negative terminal 211c of capacitor 11c is connected to source terminal 3b of semiconductor switch 3 via wiring L6c. Resistor 51c is, for example, a limiting resistor that limits the current from drive power supply 5 to capacitor 11c. The resistor 51c is connected to the wiring L2c, and the wiring L2c is located between the connection point P1c and the connection point P2c connected to the positive terminal 5a of the driving power source 5. One end of the resistor 51c is connected to the positive terminal 5a of the driving power source 5. The other end of the resistor 51c is connected to the positive terminal 111c of the capacitor 11c.

[0118] [Operation of semiconductor switch drive circuit]

[0119] Next, refer to Figure 8 to Figure 11 , the operation flow of the semiconductor switch driving circuit 6B is described. In the present embodiment, the semiconductor switch driving circuit 6B has: a first operation mode, in which the connection switching unit 13a of the semiconductor switch driving unit 6a is set to the second connection state, and the connection switching unit 13c of the semiconductor switch driving unit 6c is set to the first connection state; and a second operation mode, in which the connection switching unit 13a of the semiconductor switch driving unit 6a is set to the first connection state, and the connection switching unit 13c of the semiconductor switch driving unit 6c is set to the second connection state. The semiconductor switch driving circuit 6 alternately switches between the first operation mode and the second operation mode according to the control signal from the control device 7, thereby driving the semiconductor switch 2 and the semiconductor switch 3 to alternately become the on state.

[0120] First, refer to Figure 8 and Fig. 9 , the operation of the semiconductor switch driving unit 6a for switching the semiconductor switch 2 on or off will be described.

[0121] <First action mode>

[0122] In the first operation mode, since the connection switching unit 13a is in the second connection state, Figure 8 As shown, a negative voltage application closed circuit C13 is formed by connecting the capacitor 16a and the semiconductor switch 2. In the negative voltage application closed circuit C13, the charge charged to the capacitor 16a returns to the capacitor 16a through the path W13 via the semiconductor switch 2. The negative voltage of the capacitor 16a is supplied to the gate terminal 2c of the semiconductor switch 2, thereby the semiconductor switch 2 is turned off.

[0123] In the first operation mode, a positive voltage charging closed circuit C11 is formed by connecting the capacitor 11a to the driving power supply 5. In the positive voltage charging closed circuit C11, the current from the driving power supply 5 flows through the path W11 that returns to the driving power supply 5 via the capacitor 11a and the semiconductor switch 3. The capacitor 11a is charged by this current. In the first operation mode, a temporary charging closed circuit C12 is formed by connecting the capacitor 12a to the driving power supply 5. In the temporary charging closed circuit C12, the current from the driving power supply 5 flows through the path W12 that returns to the driving power supply 5 via the capacitor 12a and the semiconductor switch 3. The capacitor 12a is charged by this current.

[0124] <Second operation mode>

[0125] In the second operation mode, since the connection switching unit 13a is in the first connection state, Fig. 9 As shown, a positive voltage application closed circuit C14 is formed by connecting the capacitor 11a and the semiconductor switch 2. In the positive voltage application closed circuit C14, the charge charged to the capacitor 11a passes through the path W14 that returns to the capacitor 11a via the semiconductor switch 2. The positive charge of the capacitor 11a is supplied to the gate terminal 2c of the semiconductor switch 2, thereby the semiconductor switch 2 moves from the off state to the on state. In the second operation mode, a negative voltage charging closed circuit C15 is formed by connecting the capacitor 12a and the capacitor 16a. In the negative voltage charging closed circuit C15, the charge charged to the capacitor 12a flows through the path W15 that returns to the capacitor 12a via the semiconductor switch 2 and the capacitor 16a. As a result, the capacitor 16a is charged.

[0126] Next, refer to Fig.10 and Fig.11, the operation of the semiconductor switch driving unit 6c for switching the semiconductor switch 3 on or off will be described.

[0127] <First action mode>

[0128] In the first operation mode, since the connection switching unit 13c of the semiconductor switch driving unit 6c is in the first connection state (an example of the “third connection state”), Fig.10 As shown, a positive voltage application closed circuit C34 (an example of “another positive voltage application closed circuit”) is formed by connecting the capacitor 11c and the semiconductor switch 3. In the positive voltage application closed circuit C34, the charge charged to the capacitor 11c passes through the path W34 that returns to the capacitor 11c via the semiconductor switch 3. The positive charge of the capacitor 11c is supplied to the gate terminal 2c of the semiconductor switch 3, whereby the semiconductor switch 3 is turned on. In the first operation mode, a negative voltage charging closed circuit C35 is formed by connecting the capacitor 11c and the capacitor 16c. In the negative voltage charging closed circuit C35, the charge charged to the capacitor 11c and the charge of the driving power supply 5 flow through the path W35 that returns to the driving power supply 5 via the capacitor 16c. As a result, the capacitor 16c is charged.

[0129] <Second operation mode>

[0130] In the second operation mode, since the connection switching unit 13c of the semiconductor switch driving unit 6c is in the second connection state (an example of the "fourth connection state"), Fig.11 As shown, a negative voltage application closed circuit C33 (an example of “another negative voltage application closed circuit”) is formed by connecting the capacitor 16c and the semiconductor switch 3. In the negative voltage application closed circuit C33, the charge charged to the capacitor 16c passes through the path W33 that returns to the capacitor 16c via the semiconductor switch 3. The negative charge of the capacitor 16c is supplied to the gate terminal 2c of the semiconductor switch 3, whereby the semiconductor switch 3 is turned off. In the second operation mode, a positive voltage charging closed circuit C31 is formed by connecting the capacitor 11c and the drive power supply 5. In the positive voltage charging closed circuit C31, the current from the drive power supply 5 flows through the path W31 that returns to the drive power supply 5 via the capacitor 11c and the capacitor 16c. The capacitor 11c is charged by this current.

[0131] [Effects]

[0132] Next, the effects of the semiconductor switch drive circuit 6B and the power converter 1B according to the present embodiment are described. The semiconductor switch drive circuit 6B according to the present embodiment includes the same semiconductor switch drive unit 6a as the first embodiment, so the same effects as the first embodiment can be obtained. In addition, the semiconductor switch drive circuit 6B according to the present embodiment includes a semiconductor switch drive unit 6c instead of the semiconductor switch drive unit 6b. In the semiconductor switch drive unit 6a constituting the upper arm, the charging state of the capacitor 11a is switched according to the on or off of the semiconductor switch 2, so the voltage of the capacitor 11a is easy to change. On the other hand, in the semiconductor switch drive unit 6c constituting the lower arm, since the capacitor 11c can be always in a charged state, it is easy to maintain the voltage of the capacitor 11c constant. Therefore, in the lower arm, a simplified circuit structure is adopted in which a structure corresponding to the capacitor 12a is not provided, thereby reducing the number of components constituting the semiconductor switch drive unit 6c.

[0133] The present disclosure is not limited to the above-mentioned embodiments and modifications, and other various modifications are possible. For example, the above-mentioned embodiments and modifications may be combined with each other according to necessary purposes and effects. In the above-mentioned first embodiment, the case where the movement limiting portion 50a and the movement limiting portion 50b are respectively provided in the semiconductor switch driving portion 6a and the semiconductor switch driving portion 6b is described. However, the movement limiting portion 50a may be provided in the semiconductor switch driving portion 6a, and the movement limiting portion 50b may not be provided in the semiconductor switch driving portion 6b. The circuit structure of the movement limiting portion 50a is not limited to the above-mentioned example, and other circuit structures may be used as long as it can limit the movement of charge from the path W14 of the positive voltage applied closed circuit C14 to other paths.

[0134] The gist of the present disclosure is described below.

[0135] [1] A semiconductor switch driving circuit comprising:

[0136] A drive power source; and

[0137] The semiconductor switch driving unit is electrically connected to the driving power supply and drives the semiconductor switch using the power from the driving power supply.

[0138] The semiconductor switch driving unit has:

[0139] A connection switching unit, electrically connected between the driving power source and the semiconductor switch, for switching a connection state of the semiconductor switch;

[0140] a first capacitor electrically connected between the driving power source and the connection switching unit, and charged with the electric power from the driving power source to generate a positive voltage for turning on the semiconductor switch;

[0141] a second capacitor electrically connected to the driving power source in parallel with the first capacitor and charged by the electric power from the driving power source; and

[0142] a third capacitor electrically connected between the second capacitor and the connection switching unit, and charged with power discharged from the second capacitor in a charged state to generate a negative voltage for turning off the semiconductor switch,

[0143] The connection switching unit alternately switches between the first connection state and the second connection state.

[0144] In the first connection state, a positive voltage applying closed circuit is formed by electrically connecting the positive terminal of the first capacitor to the control terminal of the semiconductor switch to apply the positive voltage to the control terminal of the semiconductor switch.

[0145] In the second connection state, the negative terminal of the third capacitor is electrically connected to the control terminal of the semiconductor switch to form a negative voltage applying closed circuit for applying the negative voltage to the control terminal of the semiconductor switch.

[0146] A movement limiting portion is provided between the first capacitor and the semiconductor switch, which limits the movement of the charge of the first capacitor from a path passing through the positive voltage application closed circuit to another path passing through the positive terminal of the first capacitor and not passing through the control terminal of the semiconductor switch.

[0147] [2] A semiconductor switch driving circuit according to [1],

[0148] The movement restricting portion includes:

[0149] a first connection point between the positive terminal of the first capacitor and the control terminal of the semiconductor switch;

[0150] a second connection point between the positive terminal of the second capacitor and the input terminal of the semiconductor switch;

[0151] a third connection point, disposed between the first connection point and the positive terminal of the driving power source, and electrically connected to the positive terminal of the driving power source;

[0152] a first wiring connecting the first connection point and the third connection point; and

[0153] The second wiring connects the second connection point and the third connection point.

[0154] [3] A semiconductor switch driving circuit according to [2],

[0155] The above-mentioned movement restriction part further comprises:

[0156] a first diode connected in the first wiring with a direction from the third connection point toward the first connection point as a forward direction; and

[0157] The second diode is connected in the second wiring with a direction from the third connection point toward the second connection point as a forward direction.

[0158] [4] A semiconductor switch driving circuit according to [3],

[0159] The above-mentioned movement restriction part further comprises:

[0160] a first resistance element connected in series with the first diode in the first wiring; and

[0161] The second resistor is connected in series with the second diode in the second wiring and has a higher resistance value than the first resistor.

[0162] [5] A semiconductor switch driving circuit according to any one of [1] to [4],

[0163] The positive terminal of the first capacitor is electrically connected to the positive terminal of the driving power supply and the control terminal of the semiconductor switch.

[0164] The positive terminal of the second capacitor is electrically connected to the positive terminal of the driving power supply.

[0165] The negative terminal of the third capacitor is electrically connected to the negative terminal of the second capacitor.

[0166] A positive terminal of the third capacitor is electrically connected to a control terminal of the semiconductor switch.

[0167] [6] A semiconductor switch driving circuit according to any one of [1] to [5],

[0168] A first semiconductor switch driving unit and a second semiconductor switch driving unit are provided as the semiconductor switch driving unit.

[0169] The first semiconductor switch driving unit and the second semiconductor switch driving unit respectively drive a first semiconductor switch and a second semiconductor switch as the semiconductor switches.

[0170] The first semiconductor switch constitutes an upper arm in the semiconductor switch driving circuit.

[0171] The second semiconductor switch constitutes a lower arm in the semiconductor switch driving circuit and is electrically connected to the first semiconductor switch in series.

[0172] [7] A semiconductor switch driving circuit according to [6],

[0173] The movement limiting portion of each of the first semiconductor switch driving portion and the second semiconductor switch driving portion includes:

[0174] a first connection point between the positive terminal of the first capacitor and the control terminal of the semiconductor switch;

[0175] a second connection point between the positive terminal of the second capacitor and the input terminal of the semiconductor switch;

[0176] a third connection point, disposed between the first connection point and the positive terminal of the driving power source, and electrically connected to the positive terminal of the driving power source;

[0177] a first wiring connecting the first connection point and the third connection point; and

[0178] A second wiring connects the second connection point and the third connection point.

[0179] Only the movement limiting portion of the second semiconductor switch driving unit among the first semiconductor switch driving unit and the second semiconductor switch driving unit further comprises:

[0180] a first diode connected in the first wiring with a direction from the third connection point toward the first connection point as a forward direction; and

[0181] The second diode is connected in the second wiring with a direction from the third connection point toward the second connection point as a forward direction.

[0182] [8] A semiconductor switch driving circuit according to any one of [1] to [5], comprising:

[0183] A first semiconductor switch driving unit as the semiconductor switch driving unit drives a first semiconductor switch as the semiconductor switch; and

[0184] a second semiconductor switch driving unit electrically connected to the driving power supply, and driving a second semiconductor switch electrically connected in series with the first semiconductor switch using the electric power from the driving power supply;

[0185] The first semiconductor switch constitutes an upper arm in the semiconductor switch driving circuit.

[0186] The second semiconductor switch constitutes a lower arm in the semiconductor switch driving circuit, and the second semiconductor switch driving unit has:

[0187] Another connection switching unit is electrically connected between the driving power supply and the second semiconductor switch to switch the connection state of the second semiconductor switch;

[0188] a fourth capacitor electrically connected between the driving power source and the other connection switching unit, and charged with the electric power from the driving power source to generate a positive voltage for turning on the second semiconductor switch; and

[0189] a fifth capacitor electrically connected in series between the fourth capacitor and the other connection switching unit, and charged with power discharged from the fourth capacitor in a charged state to generate a negative voltage for turning off the second semiconductor switch,

[0190] The other connection switching unit alternately switches between the first connection state and the second connection state.

[0191] In the first connection state, the positive voltage applying closed circuit for applying the positive voltage to the control terminal of the second semiconductor switch is formed by electrically connecting the positive terminal of the fourth capacitor to the control terminal of the second semiconductor switch.

[0192] In the second connection state, the negative terminal of the fifth capacitor and the control terminal of the second semiconductor switch are electrically connected to form a negative voltage applying closed circuit for applying the negative voltage to the control terminal of the second semiconductor switch.

[0193] [9] A power converter that converts the form of power provided by a power source into the form of power required by a load device, comprising:

[0194] a semiconductor switch electrically connected between a power source and a load device; and

[0195] The semiconductor switch driving circuit described in any one of [1] to [8] is electrically connected to the semiconductor switch and drives the semiconductor switch.

[0196] Description of Reference Numerals

[0197] 1, 1A, 1B...power converter; 2...semiconductor switch (an example of "first semiconductor switch"); 3...semiconductor switch ("second semiconductor switch"); 2a, 3a...drain terminal (an example of "input terminal"); 2c, 3c...gate terminal (an example of "control terminal"); 4...power supply; 5...driving power supply; 5a...positive terminal; 5b...negative terminal; 6, 6A, 6B...semiconductor switch driving circuit; 6a, 6aa...semiconductor switch driving unit (an example of "first semiconductor switch driving unit") ; 6b, 6bb, 6c...semiconductor switch driving unit (an example of a "second semiconductor switch driving unit"); 11a...capacitor (an example of a "first capacitor"); 11c...capacitor (an example of a "fourth capacitor"); 12a...capacitor (an example of a "second capacitor"); 13a, 13b...connection switching unit; 13c...connection switching unit (an example of an "other connection switching unit"); 16a...capacitor (an example of a "third capacitor"); 16c...capacitor (an example of a "fifth capacitor"); 21a ...a diode (an example of a "first diode"); 22a...a diode (an example of a "second diode"); 31a...a resistor (an example of a "first resistor"); 32a...a resistor (an example of a "second resistor"); 50a, 50b...a movement limiting portion; 111a, 111c, 112a, 116a, 116c...a positive electrode terminal; 211a, 211c, 212a, 216a, 216c...a negative electrode terminal; C13...a negative voltage is applied to close the circuit; C14...a positive voltage is applied to close the circuit path; C33...negative voltage applied closed circuit (an example of “other negative voltage applied closed circuit”); C34...positive voltage applied closed circuit (an example of “other positive voltage applied closed circuit”); L2a...wiring (an example of “first wiring”); L5a...wiring (an example of “second wiring”); M...load device; P1a...connection point (an example of “third connection point”); P2a...connection point (an example of “first connection point”); P3a...connection point (an example of “second connection point”); W14...path.

Claims

1. A semiconductor switch driving circuit, wherein: have: A driving power source; and a semiconductor switch driving unit electrically connected to the driving power supply and driving the semiconductor switch using power from the driving power supply, The semiconductor switch driving unit comprises: A connection switching unit, electrically connected between the driving power source and the semiconductor switch, for switching a connection state of the semiconductor switch; a first capacitor electrically connected between the driving power source and the connection switching unit, and charged with the electric power from the driving power source to generate a positive voltage for turning on the semiconductor switch; a second capacitor electrically connected to the driving power source in parallel with the first capacitor and charged by the electric power from the driving power source; as well as a third capacitor electrically connected between the second capacitor and the connection switching unit, and charged with power discharged from the second capacitor in a charged state to generate a negative voltage for turning off the semiconductor switch, The connection switching unit alternately switches between a first connection state and a second connection state. In the first connection state, a positive voltage applying closed circuit is formed by electrically connecting the positive terminal of the first capacitor to the control terminal of the semiconductor switch to apply the positive voltage to the control terminal of the semiconductor switch. In the second connection state, a negative voltage applying closed circuit for applying the negative voltage to the control terminal of the semiconductor switch is formed by electrically connecting the negative terminal of the third capacitor to the control terminal of the semiconductor switch. A movement limiting portion is provided between the first capacitor and the semiconductor switch, which limits the movement of the charge of the first capacitor from a path passing through the positive voltage application closed circuit to another path passing through the positive terminal of the first capacitor and not passing through the control terminal of the semiconductor switch.

2. The semiconductor switch driving circuit according to claim 1, wherein: The movement limiting portion has: a first connection point between a positive terminal of the first capacitor and a control terminal of the semiconductor switch; a second connection point between the positive terminal of the second capacitor and the input terminal of the semiconductor switch; a third connection point, disposed between the first connection point and the positive terminal of the driving power source, and electrically connected to the positive terminal of the driving power source; a first wiring connecting the first connection point and the third connection point; and The second wiring connects the second connection point and the third connection point.

3. The semiconductor switch driving circuit according to claim 2, wherein: The movement limiting portion further comprises: a first diode connected in the first wiring with a direction from the third connection point toward the first connection point as a forward direction; and The second diode is connected in the second wiring with a direction from the third connection point toward the second connection point as a forward direction.

4. The semiconductor switch driving circuit according to claim 3, wherein: The movement limiting portion further comprises: a first resistance element connected in series with the first diode in the first wiring; and The second resistance element is connected in series with the second diode in the second wiring and has a resistance value higher than that of the first resistance element.

5. The semiconductor switch driving circuit according to claim 1, wherein: The positive terminal of the first capacitor is electrically connected to the positive terminal of the driving power source and the control terminal of the semiconductor switch. The positive terminal of the second capacitor is electrically connected to the positive terminal of the driving power supply, The negative terminal of the third capacitor is electrically connected to the negative terminal of the second capacitor, A positive terminal of the third capacitor is electrically connected to the control terminal of the semiconductor switch.

6. The semiconductor switch driving circuit according to claim 1, wherein: A first semiconductor switch driving unit and a second semiconductor switch driving unit are provided as the semiconductor switch driving unit. The first semiconductor switch driving unit and the second semiconductor switch driving unit respectively drive a first semiconductor switch and a second semiconductor switch as the semiconductor switches. The first semiconductor switch constitutes an upper arm in the semiconductor switch driving circuit. The second semiconductor switch constitutes a lower arm in the semiconductor switch driving circuit and is electrically connected to the first semiconductor switch in series.

7. The semiconductor switch driving circuit according to claim 6, wherein: The movement restriction portion of each of the first semiconductor switch driving portion and the second semiconductor switch driving portion includes: a first connection point between a positive terminal of the first capacitor and a control terminal of the semiconductor switch; a second connection point between the positive terminal of the second capacitor and the input terminal of the semiconductor switch; a third connection point, disposed between the first connection point and the positive terminal of the driving power source, and electrically connected to the positive terminal of the driving power source; a first wiring connecting the first connection point and the third connection point; and a second wiring connecting the second connection point and the third connection point, Only the movement restricting portion of the second semiconductor switch driving portion out of the first semiconductor switch driving portion and the second semiconductor switch driving portion further includes: a first diode connected in the first wiring with a direction from the third connection point toward the first connection point as a forward direction; and The second diode is connected in the second wiring with a direction from the third connection point toward the second connection point as a forward direction.

8. The semiconductor switch driving circuit according to claim 1, wherein: have: A first semiconductor switch driving unit as the semiconductor switch driving unit drives a first semiconductor switch as the semiconductor switch; and a second semiconductor switch driving unit electrically connected to the driving power supply, and driving a second semiconductor switch electrically connected in series with the first semiconductor switch using the power from the driving power supply, The first semiconductor switch constitutes an upper arm in the semiconductor switch driving circuit. The second semiconductor switch constitutes a lower arm in the semiconductor switch driving circuit. The second semiconductor switch driving unit comprises: Another connection switching unit, electrically connected between the driving power supply and the second semiconductor switch, switches the connection state of the second semiconductor switch; a fourth capacitor electrically connected between the driving power source and the other connection switching unit, and charged with the electric power from the driving power source to generate a positive voltage for turning on the second semiconductor switch; as well as a fifth capacitor electrically connected in series between the fourth capacitor and the other connection switching unit, and charged with power discharged from the fourth capacitor in a charged state to generate a negative voltage for turning off the second semiconductor switch, The other connection switching unit alternately switches between the third connection state and the fourth connection state, In the third connection state, another positive voltage applying closed circuit for applying the positive voltage to the control terminal of the second semiconductor switch is formed by electrically connecting the positive terminal of the fourth capacitor to the control terminal of the second semiconductor switch. In the fourth connection state, another negative voltage applying closed circuit for applying the negative voltage to the control terminal of the second semiconductor switch is formed by the electrical connection between the negative terminal of the fifth capacitor and the control terminal of the second semiconductor switch.

9. A power converter for converting the form of power provided by a power source into the form of power required by a load device, wherein: have: The semiconductor switch is electrically connected between the power source and the load device; and The semiconductor switch driving circuit according to any one of claims 1 to 8 is electrically connected to the semiconductor switch and drives the semiconductor switch.

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