JP2010045925A - Inverter and inverter apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase the response speed and apply a switch to an inverter of large output power, in the switch in an inverter. <P>SOLUTION: The response speed of each IGBT in inverter circuits 30 and 40 can be increased by providing the gate side of each IGBT with a capacitor. Accordingly, it is possible to design an inverter apparatus whose dead time is shortened, by providing the inverter circuits 30 and 40 with capacitors having such capacity that the response speed of the switch increases. Moreover, it is also possible to adjust the response speed of IGBT by the action of the capacitor. Accordingly, when a plurality of IGBTs are connected in series in one inverter circuit, the voltage added to each IGBT is divided into partial pressure by matching their response speed, thereby it can enlarge the breakdown voltage of the inverter apparatus 1 itself. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an inverter and an inverter device.

Some types of inverters control the frequency and current value of an alternating current supplied to the load by on / off control of a switch provided between the power supply that supplies the direct current and the load. As a technique related to such an inverter, there is one disclosed in Patent Document 1, for example.
JP 2007-267583 A

FIG. 10 is a circuit diagram showing a configuration of a conventional inverter system.
As shown in the figure, this inverter system includes an inverter device 100, a power source 2, and a load 3. The inverter device 100 is a three-phase inverter device that performs PWM (Pulse Width Modulation) control, and includes a control device 150 and three inverters 200U, 200V, and 200W. The inverters 200U, 200V, and 200W are connected to the power source 2 in parallel. The inverter 200U includes two inverter circuits 300U and 400U, and a connection end PU to which the load 3 is connected is provided between the inverter circuits 300U and 400U. The inverters 200V and 200W have the same configuration. In inverters 200U, 200V, and 200W, on / off of the switches in the inverter circuits is controlled by control device 150, and current is supplied to the loads of the respective phases of load 3 through connection terminals PU, PV, and PW. Hereinafter, when the inverters 200U, 200V, and 200W are not distinguished from each other, the alphabet at the end is omitted and referred to as “inverter 200”. The same applies to the inverter circuits 300 and 400, and the connection end is referred to as “connection end P”.

FIG. 11 is a circuit diagram showing a configuration of control device 150 and inverter 200 for one phase in inverter device 100 shown in FIG.
As shown in the figure, the inverter 200 includes inverter circuits 300 and 400 connected in series between the positive electrode and the negative electrode of the power supply 2. The inverter circuit 300 includes a resistor 31, an insulated gate bipolar transistor (hereinafter referred to as IGBT (Insulated Gate Bipolar Transistor)) 33, and a diode 34. The IGBT 33 is provided between the positive electrode of the power source 2 and the connection end P to which the load 3 is connected. The inverter circuit 400 also has a configuration equivalent to that of the inverter circuit 300, and an IGBT 43 is provided between the connection end P to which the load 3 is connected and the negative electrode of the power source 2. The IGBTs 33 and 43 of the inverter circuits 300 and 400 are each in an on state for conducting the power supply 2 and the load 3 or in an off state where the power supply 2 and the load 3 are not conducted. Functions as a switch. Control device 150 that controls on / off of IGBTs 33 and 43 has a control signal with a high potential (hereinafter, this control signal is referred to as “H”) and a control signal with a low potential (hereinafter, referred to as this control signal). "L") is output. When the control signal “H” output by the control device 150 is input to the gate of the IGBT, the gate potential rises, and the IGBT is switched from the off state to the on state. When the control signal “L” output from the control device 150 is switched, the IGBT is switched from the on state to the off state.

  By the way, in inverter apparatus 100, it is necessary to avoid “simultaneous ignition” in which IGBTs 33 and 43 are simultaneously turned on for inverters 200U, 200V, and 200W, respectively. When an arc occurs at the same time, the inverter circuit 300 and the inverter circuit 400 are short-circuited, and a large amount of electric power exceeding a specified value is supplied to the inverter device 100 and the load 3, resulting in failure of the components in the inverter system. It may cause accidents or accidents. Therefore, control device 150 outputs a control signal so that the IGBTs of inverter circuits 300 and 400 are alternately turned on so that simultaneous firing does not occur. However, a switch such as an IGBT requires a certain length of turn-on period and turn-off period. The length of these periods determines the response speed of the switch. A switch with a short turn-on period and a short turn-off period has a high response speed, and conversely, a switch with a long turn-on period and a long turn-off period has a low response speed.

In order to avoid the arc at the same time, it has been conventionally performed to provide a “dead time” that is a period in which neither of the inverter circuits 300 and 400 is made conductive. Since the elements used as switches have individual differences and response speeds vary, a dead time with a sufficiently long period is set in consideration of these variations. However, if this dead time becomes long, the waveform of the alternating current supplied to the load 3 deteriorates, which is not preferable. Therefore, when a high switching frequency such as an inverter is required, an IGBT or the like excellent in response speed is often used as a switch. However, the breakdown voltage between the collector and the emitter of the IGBT is approximately 1400V to 2000V, which is not so large. Therefore, in an inverter device with a large output power for controlling the load 3, the types of elements that can be used as switches are limited to those with a high breakdown voltage.
Accordingly, an object of the present invention is to increase the response speed of a switch in an inverter and to enable application to an inverter having a large output power.

In order to solve the above-described problems, the present invention includes first and second inverter circuits each having a plurality of switch circuits, and each of the switch circuits includes one end and the other end, and has a high level or a low level. A capacitive element connected in parallel with the resistor, the resistor having a level potential control signal input to the one end, and one end and the other end, the control signal being input to the one end A capacitive element that starts storing charges when the potential of the control signal is switched from low level to high level, and discharges the stored charge when the potential of the control signal is switched from high level to low level; Provided between a source of DC current and a load, connected to the other end of the resistor and the other end of the capacitive element, and supplied from the other end of the resistor and the other end of the capacitive element. A switch that is conductive when the potential of the control signal is high, and is non-conductive when the potential of the control signal supplied from the other end of the resistor and the other end of the capacitive element is low. And the switch included in each of the plurality of switch circuits of the first inverter circuit is connected in series between one pole of the supply source and the load, and the other pole of the supply source Provided is an inverter characterized in that the switches included in each of the plurality of switch circuits of the second inverter circuit are connected in series with the load.
An inverter according to the present invention includes first and second inverter circuits each having a plurality of switch circuits. In each switch circuit, a resistor to which a control signal is input from one end and a capacitive element are connected in parallel. These other ends are connected to a switch provided between a DC current supply source and a load. When the potential of the control signal is switched from the low level to the high level, the capacitive element starts to store electric charges from that time, and an inrush current flows through the switch and becomes conductive. When the potential of the control signal is switched from the high level to the low level, the electric charge stored in the capacitive element is released from that time, and a reverse bias is applied to the switch to lower the potential and enter a non-conductive state. In addition, between the one pole of the supply source and the load, the switches included in each of the plurality of switch circuits of the first inverter circuit are connected in series, and the other pole of the supply source and the load The switches included in the plurality of switch circuits of the second inverter circuit are connected in series. As a result, the switch is quickly switched between a conductive state and a non-conductive state, the response speed of the switch in the inverter can be increased, and the multiple switches connected in series increases the breakdown voltage of the switch circuit, The present invention can also be applied to an inverter device having a large output power.

In the inverter of the present invention, the switch is an insulated gate bipolar transistor, and the gate of the insulated gate bipolar transistor is connected to the other end of the resistor and the other end of the capacitive element, and is supplied to the gate. When the potential of the control signal is high, the collector and emitter of the insulated gate bipolar transistor may be brought into conduction.
In this inverter, when the potential of the control signal is at a high level, the insulated gate bipolar transistor as a switch is in a conducting state in which the supply source and the load are conducted through the collector and the emitter. The insulated gate bipolar transistor has excellent response speed, and the response speed of the switch can be further increased.

In addition, the present invention provides the control signal having a high-level potential via the resistor and the capacitive element to the inverter according to any one of the above-described configurations and the plurality of switches included in the first inverter circuit. Is supplied to the plurality of switches included in the second inverter circuit through the resistor and the capacitive element, and the control signal having a low level potential is supplied to the switches included in the second inverter. When the control signal having a high level potential is supplied via the resistor and the capacitive element, a low level potential is supplied to the plurality of switches included in the first inverter via the resistor and the capacitive element. There is provided an inverter device comprising control means for supplying the control signal.
The inverter device includes first and second inverter circuits each having a plurality of switch circuits. In each switch circuit, a resistor having one end connected to the control unit and a capacitive element are connected in parallel. A switch provided between a DC current supply source and a load is connected to the other ends. When the potential of the control signal supplied by the control signal is switched from the low level to the high level, the capacitive element starts to store electric charges from that time, and an inrush current flows through the switch and becomes conductive. When the potential of the control signal supplied by the control signal is switched from the high level to the low level, the charge stored in the capacitive element is released from that time, and the reverse bias is applied to the switch to lower the potential and non-conduction It becomes a state. In addition, between the one pole of the supply source and the load, the switches included in each of the plurality of switch circuits of the first inverter circuit are connected in series, and the other pole of the supply source and the load The switches included in the plurality of switch circuits of the second inverter circuit are connected in series. As a result, the switch is quickly switched between the conductive state and the non-conductive state, and the response speed of the switch in the inverter device can be increased, and the multiple switches are connected in series to increase the withstand voltage of the switch circuit. The output power of the inverter device of the present invention can be increased.

In the inverter device of the present invention, the capacitive elements of the plurality of switch circuits included in the first and second inverter circuits are one or a plurality of capacitive elements in which a total sum of the capacitances changes, and the control Period specifying means for specifying a difference between the periods from when the high-level control signal is supplied by the means until each of the switches included in the inverter circuit to which the control signal is supplied becomes conductive; and When the difference between the periods specified by the specifying means is large, the total sum of the capacitances of the one or more capacitive elements in the plurality of switch circuits including the respective switches is changed so that the difference becomes small. Capacity control means may be provided.
In the inverter device, the plurality of switch circuits include one or a plurality of capacitive elements whose total capacitance changes, and the period specifying unit is supplied with the control signal after the high-level control signal is supplied. The difference between the periods until the respective switches included in the inverter circuit are turned on is specified, and the capacity control means reduces the difference when the difference between the periods specified by the period specifying means is large. In addition, the sum of the capacities of the capacitive elements included in each inverter circuit is changed. When the total capacitance of the capacitive elements is changed, the response speed of the switch changes. Therefore, it is possible to perform control to match them while increasing the response speed of the switch included in each inverter circuit in its own device. Are connected in series, the withstand voltage of the switch circuit is increased, and the output power can be increased.

  ADVANTAGE OF THE INVENTION According to this invention, in the switch in an inverter, while making the response speed high, it becomes possible to apply to an inverter with big output electric power.

Next, the best mode for carrying out the present invention will be described with reference to the drawings.
(A) First Embodiment First, a first embodiment of the present invention will be described.
FIG. 1 is a circuit diagram showing a configuration of an inverter system in the present embodiment.
As shown in the figure, this inverter system includes an inverter device 1, a power source 2 and a load 3. The inverter device 1 is an inverter device employing a three-phase voltage type PWM inverter that converts DC power supplied from a power source 2 into AC power and outputs the AC power to a load 3. The inverter device 1 includes a control device 10 and three inverters 20U, 20V, and 20W for supplying a three-phase alternating current to the load 3. The inverters 20U, 20V, and 20W are connected to the power supply 2 in parallel. The inverter 20U includes an inverter circuit 30U and an inverter circuit 40U connected in series with each other. Similarly, the inverter 20V has inverter circuits 30V and 40V connected in series with each other, and the inverter 20W has inverter circuits 30W and 40W connected in series with each other. In the inverters 20U, 20V, and 20W, connection points of both inverter circuits included in the inverters 20U, 20V, and 20W are connection ends PU, PV, and PW, and current is supplied to the load 3 through these connection ends PU, PV, and PW. Is done. The control device 10 controls the current value of the alternating current supplied to the load 3 through the PWM control or the voltage value, frequency, and phase of the alternating voltage.
In addition, since the configurations of the inverters 20U, 20V, and 20W are the same, in the following, when they are not distinguished, the alphabet at the end is omitted and referred to as “inverter 20”. The same applies to the inverter circuits 30 and 40, and the connection ends are collectively referred to as “connection ends P”.

  The power source 2 functions as a DC current supply source. For example, a converter that converts an AC current supplied from a commercial power source into DC power and supplies the inverter device 1 or a DC current to the inverter device 1 is supplied. A storage battery or the like. The load 3 is operated by receiving a three-phase alternating current from the inverter device 1 by connecting three-phase loads including a U-phase, a V-phase, and a W-phase by Y connection. The load 3 here is a load such as a motor that requires a large amount of electric power to drive the load 3, and is a dynamometer for performing a vehicle collision test, for example. In the dynamometer, the endurance test is performed while simulating the actual vehicle running pattern on the table. In this case, the inverter device 1 performs control (PWM control) such that the generated torque and the rotation speed of the dynamometer are controlled and vehicle collision tests can be performed under various collision conditions.

FIG. 2 is a circuit diagram showing a configuration of the inverter device 1. In the same figure, the control apparatus 10 and the inverter 20 for 1 phase are shown among the inverter apparatuses 1 shown in FIG.
The control device 10 includes a CPU, a memory, a drive circuit, and the like provided on the substrate, and controls each part in the inverter device 1. The control device 10 outputs a control signal, which is a pulse signal, to the inverter 20 in accordance with a control command such as a start command, a rotation speed command, or a generated torque command input from the outside in order to control driving of the load 3. . Here, the control device 10 supplies either a high-level control signal “H” with a high potential or a low-level control signal “L” with a low potential. A drive circuit (not shown) provided in the control device 10 is, for example, a high-speed photocoupler. The control device 10 in the inverter device 1 and the circuit part of the control system in the inverter 20 and the power system to which the current from the power source 2 is supplied. Is electrically insulated from the circuit portion of

The inverter circuit 30 includes switch circuits 30X and 30Y connected in series between the positive electrode of the power supply 2 and the connection end P.
The switch circuit 30X includes a resistor 31, a capacitor 32, an IGBT 33, and a diode 34. The resistor 31 includes one end and the other end, and a control signal “H” or “L” from the control device 10 is input to one end thereof. The capacitor 32 is a capacitive element having one end and the other end and connected in parallel with the resistor 31. In the IGBT 33, the gate G <b> 1 is connected to the other end of the resistor 31 and the other end of the capacitor 32. The collector C1 of the IGBT 33 is connected to the positive electrode of the power supply 2. The IGBT 33 functions as a switch that takes either an on state that is a conducting state or an off state that is a non-conducting state. For example, when the control signal supplied from the control device 10 via the resistor 31 and the capacitor 32 is “H”, the IGBT 33 is turned on to conduct the collector C1 and the emitter E1. On the other hand, when the control signal supplied from the control device 10 via the resistor 31 and the capacitor 32 is “L”, the IGBT 33 does not conduct the collector C1 and the emitter E1, that is, does not conduct the power supply 2 and the load 3. It becomes a state. The diode 34 is a unidirectional element connected in a reverse direction between the collector C1 and the emitter E1 of the IGBT 33. The diode 34 is provided to secure a supply path for a transient current so that the IGBT 33 is not damaged when the IGBT 33 is switched from the on state to the off state.

The switch circuit 30Y includes a resistor 35, a capacitor 36, an IGBT 37, and a diode 38. The switch circuit 30Y has the same configuration as the switch circuit 30X, and includes a resistor 31, a capacitor 32, an IGBT 33, and a diode 34, a resistor 35, a capacitor 36, an IGBT 37, and a diode 38, respectively. The configuration is equivalent to the replaced one. The collector C2 of the IGBT 37 is connected to the emitter E1 of the IGBT 33 of the switch circuit 30X. The emitter E2 is connected to the load 3 via the connection end P. The IGBT 37 also functions as a switch. When the control signal supplied from the control device 10 via the resistor 35 and the capacitor 36 is “H”, the collector C2 and the emitter E2 are turned on. When the control signal is “H”, the IGBT 33 is in the ON state as described above. At this time, the power source 2 and the load 3 are conducted through the IGBTs 33 and 37. Therefore, the IGBT 37 supplies the current supplied from the power source 2 via the IGBT 33 to the load 3 via its collector C2 and emitter E2. On the other hand, when the control signal supplied from the control device 10 via the resistor 35 and the capacitor 36 is “L”, the IGBT 37 does not conduct the collector C4 and the emitter E4, that is, does not conduct the power supply 2 and the load 3. It becomes a state.
Under such a configuration, in the inverter circuit 30, when both the IGBTs 33 and 37 are in the ON state, the current supplied from the positive electrode of the power source 2 is supplied to the load 3 via the IGBT 33, the IGBT 37 and the connection terminal P. . On the other hand, when either one of the IGBT 33 and the IGBT 37 is in an OFF state, the inverter circuit 30 does not supply a current from the power source 2 to the load 3.

The inverter circuit 40 includes switch circuits 40X and 40Y connected in series between the connection end P and the negative electrode of the power source 2.
The switch circuit 40X includes a resistor 41, a capacitor 42, an IGBT 43, and a diode 44, and has a circuit configuration equivalent to that of the switch circuit 30X of the inverter circuit 30. The collector C3 of the IGBT 43 is connected to the emitter E2 of the IGBT 37 of the switch circuit 30Y, and is connected to the load 3 via the connection end P. The IGBT 43 also functions as a switch. When the control signal supplied from the control device 10 is “H”, the IGBT 43 is turned on to conduct the collector C3 and the emitter E3. On the other hand, when the control signal supplied from the control device 10 via the resistor 41 and the capacitor 42 is “L”, the collector C3 and the emitter E3 are not conducted, that is, the power supply 2 and the load 3 are not conducted. Become.

The switch circuit 40Y includes a resistor 45, a capacitor 46, an IGBT 47, and a diode 48. The switch circuit 40Y has the same configuration as the switch circuit 30Y. The collector C4 of the IGBT 47 is connected to the emitter E3 of the IGBT 43 of the switch circuit 40X. The emitter E4 is connected to the negative electrode of the power source 2. The IGBT 47 also functions as a switch. When the control signal supplied from the control device 10 via the resistor 45 and the capacitor 46 is “H”, the collector C4 and the emitter E4 are turned on. On the other hand, when the control signal supplied from the control device 10 via the resistor 45 and the capacitor 46 is “L”, the collector C4 and the emitter E4 are not conducted, and the load 3 and the power source 2 are not conducted. .
Under such a configuration, in the inverter circuit 40, when both the IGBT 43 and the IGBT 47 are in the ON state, the current supplied from the load 3 via the connection terminal P is supplied to the negative electrode of the power source 2. On the other hand, when either one of the IGBT 43 and the IGBT 47 is in an OFF state, the inverter circuit 40 does not supply a current from the load 3 to the power source 2.

  As described above, in the inverter device 1, the IGBTs 33 included in each of the plurality of switch circuits 30 </ b> X and 30 </ b> Y of the inverter circuit 30 that is the first inverter circuit between the positive electrode that is one pole of the power source 2 and the load 3. 37 are connected in series. Further, between the negative electrode, which is the other pole of the power source 2, and the load 3, IGBTs 43, 47 respectively included in the plurality of switch circuits 40X, 40Y of the inverter circuit 40, which is the second inverter circuit, are connected in series. Yes. With this configuration, when the inverter device 1 controls the driving of the load 3, the voltage applied to one IGBT functioning as a switch is divided. That is, the voltage applied between the collector and the emitter of the IGBT is ½ compared to the case where the switch circuit has only one switch. Since the voltage applied to the IGBT is divided and reduced according to the number of switch circuits connected in series, the output power to the load 3 is large, and a large current is supplied from the power source 2 to the inverter device 1 for driving. Even in this case, each switch (IGBT) in the inverter device 1 does not need to be applied with a voltage higher than its withstand voltage.

In the inverter 20, capacitors 32 and 36 are provided in the inverter circuit 30, and capacitors 42 and 46 are provided in the inverter circuit 40. The reason will be described below.
As shown in FIG. 2, in the inverter circuit 30, the capacitor 32 is connected in parallel to the resistor 31, the capacitor 36 is connected in parallel to the resistor 35, and in the inverter circuit 40, the capacitor 42 is connected to the resistor 41. The capacitor 46 is connected in parallel to the resistor 45. Capacitors 32, 36, 42, and 46 provided on the gate sides of these IGBTs are switched from the on-state to the off-state during the turn-on period when the IGBTs 33, 37, 43, and 47 are switched from the off-state to the on-state, respectively. This is provided in order to shorten the turn-off period. Also, in each switch circuit, if a large current is supplied from the power supply 2 when all the IGBTs are not in the ON state, a voltage exceeding the withstand voltage may be applied between the collector and the emitter of the IGBT, resulting in damage. is there. Therefore, by the action of these capacitors, the response speed of the IGBT is increased and the response speeds of the plurality of IGBTs are made to coincide with each other.

The action of the capacitor provided on the gate side of the IGBT will be specifically described. In addition, since the effect | action of each capacitor | condenser is respectively the same, the switch circuit 30X containing the capacitor | condenser 32 is mentioned as an example and demonstrated here.
3, (a) is a time chart showing how the control device 10 outputs a control signal, and (b) is a time chart showing how the gate current IG flowing into the gate G1 of the IGBT 33 changes. is there. In FIG. 9A, the period during which the control signal “H” is output is represented by “H”, and the period during which the control signal “L” is output is represented by “L”. Further, in FIG. 7B, the current value when the gate current IG flows from the control device 10 toward the gate G1 of the IGBT 33 is represented by positive, and when the gate current IG flows from the gate G1 toward the control device 10 The current value is expressed as negative. It is assumed that a control signal “L” is output by the control device 10 before time t = ta shown in the figure, and no charge is stored in the capacitor 32 during this period. FIG. 4 is a diagram for explaining the state of the gate current IG flowing in the switch circuit 30X at each time and period shown in FIG.

  First, as shown in FIG. 3A, when the control signal output from the control device 10 is switched from “L” to “H” at time t = ta, as shown in FIG. A gate current IG corresponding to the control signal “H” flows into the gate G 1 of the IGBT 33. The current path at this time is as shown in FIG. 4A, and the gate current IG flows from the control device 10 via the capacitor 32. When the control signal output from the control device 10 is switched from “L” to “H”, the control device 10 side becomes higher potential than the capacitor 32 side, and the electric charge is supplied from the control device 10 to the capacitor 32 by this potential difference. As a result, the capacitor 32 starts to store electric charge. At this time, the current supplied to the capacitor 32 is called an inrush current, and the current value is relatively large. Therefore, as shown in FIG. 3B, the current value of the gate current IG is also increased to Is (> 0). As described above, due to the action of the large current flowing at the start of charging, each carrier in the IGBT 33 moves smoothly and the gate potential easily rises. The fact that the gate potential rises early means that the collector C1 and the emitter E1 are brought into conduction early. Therefore, compared with the configuration in which the capacitor 32 is not provided, the IGBT 33 is quickly switched from the off state to the on state, and the turn-on period is shortened. Note that, as shown in FIG. 3B, since the charging speed decreases as time elapses after the control signal is switched from “L” to “H”, the gate current IG also gradually decreases. To go.

  Subsequently, as shown in FIG. 3A, during the period in which sufficient charge is stored in the capacitor 32 and the control signal “H” is output by the control device 10, the period tb shown in FIG. Thus, the gate current IG having a current value If (> 0) smaller than the current value Is of the inrush current flows. At this time, as shown in FIG. 4B, the gate current IG flows from the control device 10 via the resistor 31 to the gate G1 of the IGBT 33, and the gate current IG does not flow to the capacitor 32 side. Accordingly, a gate current IG having a constant current value If flows through the resistor 31 to the gate G1 of the IGBT 33 in accordance with the control signal “H” having a constant potential.

  As shown in FIG. 3A, when the control signal output from the control device 10 is switched from “H” to “L” at time t = tc, as shown in FIG. A gate current IG corresponding to this switching flows. The current value Ir of the gate current IG at this time is negative, and the gate current IG flows from the gate G1 of the IGBT 33 to the control device 10 via the capacitor 32 as shown in FIG. The current value of the gate current IG suddenly rises to the negative current value Ir due to the action of the charge stored in the capacitor 32. When the control signal output from the control device 10 is switched from “H” to “L”, the stored charge is transferred from the high-potential side capacitor 32 storing the charge to the low-potential side control device 10. Released. At this time, since a reverse bias is also applied to the gate G1 of the IGBT 33 on the high potential side, a gate current IG having a large current value flows through the current path as shown in FIG. By this current, the minority carriers existing between the gate G1 and the collector C1 of the IGBT 33 move so as to quickly return to the off state. By this action, the gate potential of the IGBT 33 is quickly lowered. In this way, the carrier moves more smoothly than in the configuration in which the capacitor 32 is not provided, the IGBT 33 is quickly switched from the on state to the off state, and the turn-off period is shortened. Note that after the time t = tc, the discharge rate gradually decreases with time, so that the gate current IG gradually decreases. When the discharge of the capacitor 32 is completed, the gate current IG stops flowing.

  Further, as shown in FIG. 3B, at time t = td, the control signal output from the control device 10 is switched from “L” to “H”, and the control signal of “H” at the period t = te. Is output and is switched from “H” to “L” at time t = tf. At this time as well, the IGBT 33 is switched on and off in the same manner as described above. Also, in the same principle as this, in the switch circuit 30Y and the switch circuits 40X and 40Y of the inverter circuit 40, both the turn-on period and the turn-off period of the IGBT are shortened by the action of the capacitor. That is, the response speed of the IGBTs 33, 37, 43, and 47 that are the switches of the inverter 20 is higher than that in the configuration in which the capacitors 32, 36, 42, and 46 are not provided.

The response speed of each IGBT depends on the capacitance of the capacitor provided on the gate side. Here, FIG. 5 is a graph schematically showing the relationship between the capacitance of the capacitor and the response speed of the IGBT.
As shown in the figure, the response speed of the IGBT tends to increase as the capacitance of the capacitor increases. As described above, in turn-on, the inrush current flows as the gate current IG when the control signal is switched from “L” to “H”. The greater the capacitance of the capacitor, the greater the amount of charge that can be stored, so that a larger current flows as the gate current IG. As a result, the gate potential is further easily increased, and the IGBT is more smoothly switched from the off state to the on state. Further, even when the control signal output by the control device 10 is switched from “H” to “L”, the larger the capacitance of the capacitor, the larger the amount of charge that is released. The movement is smoother and the turn-off period is shortened. For this reason, the response speed of the IGBT increases as the capacitance of the capacitor increases.
However, even if the capacitance of the capacitor is too large, if the potential between the gate and emitter reaches the potential in the saturated state (ON state), the capacitor will not be charged any further and the response speed will be high. It will never be. Therefore, it is desirable that the capacitor has an appropriate capacity according to the breakdown voltage of the IGBT and the load characteristics of the load 3. The same operation is obtained for each of the inverters 20U, 20V, and 20W.

  According to the first embodiment described above, the response speed of each IGBT of the inverter circuits 30 and 40 can be increased by providing a capacitor on the gate side of each IGBT in the switch circuit constituting the inverter. Therefore, if a capacitor having a capacitance that increases the response speed of the switch is provided in each of the inverter circuits 30 and 40, an inverter device with a short dead time can be designed. In addition, the response speed can be adjusted by the action of a capacitor provided at the gate of the IGBT. Therefore, as shown in FIG. 1, when a plurality of IGBTs are connected in series in one inverter circuit, the voltage applied to each IGBT is divided by matching their response speeds, and the inverter device 1 itself The breakdown voltage can be increased. Thereby, even if the output power supplied from the inverter device 1 to the load 3 is large, it is possible to design an inverter device in which a voltage higher than the withstand voltage is not applied to each IGBT.

(B) Second Embodiment Next, a second embodiment of the present invention will be described.
FIG. 6 is a circuit diagram showing the configuration of the inverter system of the present embodiment.
As shown in the figure, this inverter system has a configuration in which a plurality of potential detectors and a booster 4 that boosts the power supply voltage of the power supply 2 are added to the inverter system of the first embodiment. In the following description, the same components as those of the inverter system described in the first embodiment are denoted by the same reference numerals.
The inverter device 1a includes a control device 10a and three inverters 20Ua, 20Va, and 20Wa. The inverter 20Ua is configured by connecting two inverter circuits 30Ua and 40Ua in series. The inverter 20Va is configured by connecting inverter circuits 30Va and 40Va in series. The inverter 20Wa includes inverter circuits 30Wa and 40Wa in series. Connected and configured. In the inverter device 1a, the potential detector 50U that detects the potential of the connection end PU in the inverter 20Ua, the potential detector 50V that detects the potential of the connection end PV in the inverter 20Va, and the potential of the connection end PW in the inverter 20Wa. And a potential detector 50W for detecting the above. The inverter circuit 40Ua of the inverter 20U is provided with a potential detector 60U that detects the potential between the switches (IGBT) included therein, and the inverter circuit 40Va of the inverter 20V detects the potential between the switches included therein. A potential detector 60V for detecting the potential between the switches included in the inverter circuit 40Wa of the inverter 20W is provided. In addition, since the configurations of the inverters 20Ua, 20Va, and 20Wa are the same, the inverters 20Ua, 20Va, and 20Wa are referred to as “inverters 20a” when they are not distinguished. Similarly, the switch circuits are also referred to as inverter circuits 30a and 40a. When the potential detectors 50U, 50V, and 50W are not distinguished from each other, they are referred to as “potential detector 50”. When the potential detectors 60U, 60V, and 60W are not distinguished from each other, they are referred to as “potential detector 60”. Called.

  The potential detectors 50 and 60 are, for example, voltmeters provided in the inverter device 1a, and periodically output the detection result of the potential measured by each to the control device 10a. The potential detectors 50 and 60 detect the potential at each position with reference to the ground potential (not shown). The control device 10a controls each part in the inverter device 1a based on the detection result acquired from the potential detector 50, and controls boosting (voltage magnitude) by the boosting device 4 provided in the inverter device 1a. To do. The booster 4 has a booster circuit using a booster transformer, for example, under the control of the control device 10a, boosts the voltage of the power supply 2, and supplies a current corresponding to the voltage into the inverter device 1a. Specifically, the booster 4 supplies a large DC current in the inverter control to each of the inverters 20U, 20V, and 20W, and whichever of the IGBTs is turned on, the IGBT 4 has a higher withstand voltage than the IGBT. A current (adjustment current) having a sufficiently small current value so that only a low voltage is applied is supplied to each of the inverters 20U, 20V, and 20W.

FIG. 7 is a circuit diagram showing a configuration of the inverter device 1a. In addition, in the same figure, the control apparatus 10a with which the inverter apparatus 1a is provided, and the inverter 20a for 1 phase are shown.
As shown in the figure, the inverter device 1a is provided with variable capacitors 32a, 36a, 42a, 46a whose total capacitance changes in place of the capacitors 32, 36, 42, 46 in the inverter device 1 described above. ing. The variable capacitors 32a, 36a, 42a, and 46a have their total capacitance changed under the control of the control device 10a. Note that, as shown in FIG. 7, here, only one variable capacitor, which is a capacitive element, is provided in each of the switch circuits of the inverter circuits 30a and 40a. This means the capacitance of the variable capacitors 32a, 36a, 42a, 46a alone. In addition, the control device 10a includes a timer capable of measuring the time, and the variable capacitors 32a, 36a, A “capacitance control process” for controlling the capacitances 42a and 46a is executed.
As described above, in the first embodiment described above, the optimum capacitor capacity is determined at the design stage, whereas in the second embodiment, the control device 10a appropriately determines the capacitance of the capacitor by the capacity control process. Both are different in that they are controlled.

  Next, an example of “capacity control processing” executed by the control device 10a will be described. During the capacity control process, the control device 10a controls the booster 4 so that the adjustment current is supplied into the inverter device 1a. This is control for preventing a voltage exceeding the withstand voltage from being applied to each IGBT in the capacity control process. In addition, when the capacity control is performed on the inverter circuit 30U in the inverter 20U, the control device 10a turns off the IGBT of the inverter circuit 40U and turns on both the IGBTs 43 and 47 of the inverter circuits 40V and 40W. Leave it in a state. Further, when the capacity control process is performed on the inverter circuit 40U, the control device 10a turns off the IGBT of the inverter circuit 30U and turns on either of the IGBTs 33 and 37 of the inverter circuits 30Va and 30Wa. deep. This is because when the control device 10a performs a capacity control process on a certain inverter circuit, a current is generated in the inverter system when both IGBTs of the inverter circuit to be controlled are turned on while preventing simultaneous firing. This is to allow the flow. The control device 10a performs the capacity control process on the other inverter circuits under the same conditions.

Next, the “capacity control process” will be specifically described with reference to FIG. Hereinafter, a case where the capacity control process is executed on the inverter circuit 30 will be described.
FIG. 8 is a time chart showing whether each of the IGBT 33 and the IGBT 37 in the inverter circuit 30 is in an on state (ON) or an off state (OFF). In the figure, the horizontal axis represents time t.

When performing the capacity control process of the inverter circuit 30a, the control device 10a first intentionally makes the capacitance of the variable capacitor 32a of the switch circuit 30Xa sufficiently smaller than the capacitance of the variable capacitor 36a of the switch circuit 30Ya. That is, the control device 10a sets the response speed of the IGBT 33 of the switch circuit 30Xa to be lower than the response speed of the IGBT 37 of the switch circuit 30Ya.
Subsequently, when the control signal to be output to the inverter circuit 30 is switched from “L” to “H”, the control device 10a starts timing by the timer at that timing. The IGBTs 33 and 37 to which the control signal “H” is supplied are eventually turned on. Here, it is assumed that the states of the IGBTs 33 and 37 are as shown in “state A” shown in FIG. 8. That is, the time t = 0 when the IGBT 37 is turned on and the time t = T1 after the time t = 0 is the time when the IGBT 33 is turned on. In this case, the control device 10a identifies the time when both the IGBT 33 and the IGBT 37 are turned on as t = T1 according to the detection result of the potential by the potential detector 50. When both IGBTs 33 and 37 are switched on at time t = T1, current from the power supply 2 starts to flow through the inverter circuit 30 and the connection terminal P, and the connection terminal P detected by the potential detector 50 This is because the potential increases. Therefore, the control device 10a determines the time indicated by the timer when the potential detected by the potential detector 50 is equal to or higher than the first threshold value indicating the potential when both the IGBTs 33 and 37 are turned on. , Specify the time when both turned on. Hereinafter, the time at which all IGBTs turn on in one inverter circuit is referred to as “turn-on time”.

  Subsequently, the control device 10a switches the control signal output to the inverter circuit 30 from “H” to “L”. Then, the control device 10a increases the capacitance of the variable capacitor 32a whose capacity is intentionally reduced by a predetermined amount, and switches the control signal supplied to the inverter circuit 30 from “L” to “H” again. At the same time, timing by the timer is started. In this case, the response speed of the IGBT 33 is increased by increasing the capacitance of the variable capacitor 32a. Therefore, the time when each of the IGBTs 33 and 37 is turned on is as shown in “state B” shown in FIG. That is, the difference in response speed between the IGBT 33 and the IGBT 37 is reduced, and the control device 10a can specify from the detection result of the potential detector 50 that the turn-on time is a time t = T2 earlier than T1. . Thereafter, similarly to the above, the control device 10a gradually increases the capacitance of the variable capacitor 32a and specifies the turn-on time based on the detection result of the potential detector 50. When this is repeated, the turn-on times of the IGBT 33 and the IGBT 37 coincide with each other at t = 0 as in the “state C” shown in FIG.

  Next, when the control device 10a increases the capacity of the variable capacitor 32a, the turn-on times of the IGBTs 33 and 37 are in a “state D” shown in FIG. That is, the turn-on time of the IGBT 33 is a time t = T3 that is earlier than the time t = 0. However, the turn-on time is t = 0 and has not changed. This is because the capacitance of the variable capacitor 36a has not changed. That is, thereafter, no matter how much the control device 10a increases the capacitance of the variable capacitor 32a, the turn-on time remains t = 0 as long as the capacitance of the variable capacitor 36a is the same.

Based on this principle, the control device 10a gradually increases the capacitance of the variable capacitor 32a of the switch circuit 30Xa whose capacitance has been intentionally reduced, and determines that the turn-on time does not become earlier. In addition, it is specified that the response speeds of the IGBT 33 and the IGBT 37 match. In the example shown in FIG. 8, the control device 10a specifies that the turn-on time has not become early when the state “state D” is entered. Are matched, the variable capacitor 32a is controlled so as to obtain the capacitance at this time. Here, the control device 10a completes the capacity control process for the inverter circuit 30.
If the response speeds cannot be matched exactly, the control device 10a controls the capacitance of each variable capacitor so that the difference is as small as possible. In this capacity control process, if the control device 10a wants to make it higher than the response speed, the control device 10a may increase the capacitance of the variable capacitor 36a from here, and whether or not the response speed is deviated. When confirming this, it is only necessary to confirm the change in the turn-on time by changing the capacitance of one of the variable capacitors in the same manner as described above.

  Subsequently, the control device 10a performs the same control on the inverter circuit 40a to control the capacities of the variable capacitors 42a and 46a. In this case, the control device 10a specifies the turn-on time based on the potential of the potential detector 60 provided between the switch circuit 40Xa and the switch circuit 40Ya in the inverter circuit 40a in the same manner as described above. The potential detector 60 is provided between the switch circuit 40Xa and the switch circuit 40Ya because the potential detected by the potential detector 60 is high only when both the IGBTs 43 and 47 are turned on. This is because any one of the potentials does not rise when it is off.

The control device 10a controls the capacitance of the variable capacitor for all of the inverters 20U, 20V, and 20W. After controlling the capacitance of the variable capacitor based on the above algorithm, the control device 10a resets the dead time according to the response speed of the IGBT of each inverter circuit. In the setting of the dead time, for example, the relationship between the turn-on period and the dead time is stored in advance in the memory of the control device 10a, and the control device 10a sets the dead time based on this correspondence relationship. Further, the control device 10a may calculate the dead time based on a predetermined algorithm using the specified length of the turn-on period, and set the calculated dead time.
In this capacity control process, the control device 10a controls the capacity of the variable capacitor so that one of the IGBTs in the same inverter circuit has the shortest response speed and the response speed of the other IGBTs is matched to that. Also good. Further, the control device 10a may control the capacitance of the variable capacitor so as to match a predetermined target value. The control device 10a may perform control so that the response speeds of all IGBTs in the inverter device 1a are matched, but at least the response speeds of the IGBTs are matched in each inverter circuit.

  According to the second embodiment described above, the control device 10a matches the response speeds of the plurality of IGBTs included in the inverter circuits 30 and 40 in the inverter 20 at an arbitrary timing such as periodically or during maintenance. Control the capacitance of the variable capacitor. As a result, even when there is a change in the response speed of the IGBT over time, a change in temperature, or the like, the inverter device 1a responds quickly, and when the response speed of the IGBT is shifted in the inverter circuit, The capacity of the variable capacitor is controlled so as to match. With this configuration, the inverter device 1a itself can always cope with the control of a high-capacity load even if an operator does not perform complicated work such as adjustment and replacement of the capacitor capacity. The high performance can be secured continuously.

(C) Modification The above embodiment may be modified as follows. These modifications can be appropriately combined with each other.
In the second embodiment described above, the variable capacitors 32a, 36a, 42a, and 46a are used. However, the configuration for changing the total sum of the capacitances of the capacitors may be as follows.
FIG. 9 is a circuit diagram of the switch circuit 30Xa that employs a configuration in which the total capacitance of the capacitors changes without using a variable capacitor. As shown in the figure, the switch circuit 30Xa has a configuration in which the variable capacitor 32a of the second embodiment is replaced with a capacitor portion 32b. Although not shown, the same configuration can be used for the switch circuit 30Ya and the inverter circuit 40a.
As shown in the figure, in the capacitor part 32 b, a plurality of series circuits each including a switch SW, i and a capacitor 72-i (i = 1 to 5) are connected in parallel to the resistor 31. Each of the switches SW1 to SW5 is a switch using a MOSFET (field effect transistor) or the like, and the control device 10a controls each on / off. Note that the switches SW1 to SW5 do not require a high response speed unlike the IGBT 33. The capacitances of the capacitors 72-1 to 72-5 are, for example, 1 pF, 2 pF, 4 pF, 8 pF, and 16 pF, respectively.

As in the second embodiment, when the control device 10a controls the optimum capacitance for each inverter 20a, each switch SW1 to SW5 of the capacitor unit 32b is realized so as to realize this capacitance. Controls on / off. That is, the total sum of the capacities varies depending on the combined capacity of the plurality of capacitors in the capacitor section 32b. In the switch circuit 30Xa, since these five series circuits are connected in parallel, it is possible to realize 2 ⁵ = 32 different capacitances by combining them. Note that the number of stages of the parallel circuit and the capacity of each capacitor are merely examples, and the capacity may be controlled more precisely by increasing the number of stages. In addition, a plurality of capacitors may be connected in series as well as connected in parallel. If series connection is adopted, if you want to change the capacitance of the capacitor in pico order, you can achieve this by combining a capacitor with a fixed capacitance of micro order without using a variable capacitor whose capacitance changes in pico order. Can do. In the second embodiment described above, a plurality of variable capacitors of each switch circuit may be provided in series connection or parallel connection.

Further, in the second embodiment described above, the potential detectors 50 and 60 are used. However, instead of this, the following configuration may be adopted.
The installation examples of the potential detectors 50 and 60 described in the second embodiment are merely examples, and may be provided so as to detect a potential at a position where the turn-on period or turn-off period of each IGBT can be measured. .
For example, instead of the potential detector 50, an ammeter that detects the magnitude of the current flowing through the load 3 or a wattmeter that detects the magnitude of power may be used. Instead of the potential detector 60, an ammeter that detects the magnitude of the current flowing between the two IGBTs or a wattmeter that detects the magnitude of the power may be used. Even in this configuration, the turn-on time in the inverter circuit can be specified from the current value and the rise of power, and the same effect as in the second embodiment can be obtained. In addition, the detector may not be a detector that measures the values of current, potential, and power itself. For example, a detection that outputs a notification signal when the measurement result is equal to or higher than a first threshold value that means that turn-on is completed. A vessel may be used.
In short, each IGBT provided in the inverter circuit to which the control signal “H” is supplied after the control signal “H” is supplied by the control device 10 a by the cooperation of the control device 10 a and the detector is turned on. Identify the difference in period until. And when the difference of the period is large, the control apparatus 10a should just be the structure which changes the sum total of the capacity | capacitance of the variable capacitor of the switch circuit provided with these switches so that the difference may be made small.

  In the first and second embodiments described above, two switches (IGBT) are connected in series for each of the inverter circuits 30 and 40, but the number may be larger than this. As the number of IGBTs connected in series increases, the voltage applied between the collector and emitter of each IGBT decreases, so that a larger output power can be reliably supplied to the load 3. Also in this case, in each inverter circuit, the capacitance of each variable capacitor may be adjusted so that the response speeds of the IGBTs of the plurality of switch circuits match.

Also in the capacity control process described in the second embodiment described above, the control device 10a can execute the capacity control process based on the same algorithm as described above.
Specifically, the control device 10a specifies the turn-on time while keeping the capacitance of any variable capacitor in the inverter circuit sufficiently small and gradually increasing it. If the control device 10a determines that the turn-on time does not advance even if the capacity of the variable capacitor is increased, the IGBT of the switch circuit including the variable capacitor matches the response speed of any other IGBT. Identifies At this time, if it is not known to which IGBT the response speed matches, the control device 10a reduces the capacitance of any variable capacitor, and includes the variable capacitor when the turn-on time is delayed. It can be specified that the response speed matches the IGBT of the switch circuit. Even in this embodiment, the potential detector 50 may be provided so as to detect the potential of the connection terminal P. Also in the potential detector 60, one inverter circuit is provided between the switch circuits. It is sufficient that only one is provided.

In this aspect, if a certain large difference is provided in the capacitances of the variable capacitors of the plurality of switch circuits, and the order of the response speeds of the IGBTs is determined in advance, then the capacitance control process is performed, The algorithm becomes simpler. This algorithm can be used even when the number of IGBTs connected in series is further increased. In the capacity control process, the control device 10a may control the capacity of the variable capacitor based on other algorithms. If the response speed of the IGBT can be matched for each inverter circuit, the content of the capacity control process is as follows: Other than this may be used.
Further, in this configuration, the aspect in which the response speed of the IGBT having a low response speed is matched with the one having a high response speed has been described. However, the control device 10a intentionally increases the capacitance of the variable capacitor of a certain switch circuit. By gradually decreasing this, the response speed of the IGBT having a high response speed may be matched with that having a low response speed. Further, as in the first and second embodiments, the control device 10a is not limited to matching the response speed based on the turn-on time, but may be matched based on the period required for turn-off.

In the first and second embodiments described above, the IGBT is used as the switch in the inverter circuit, but the element used as the switch is not limited to the IGBT. As described above, a large current flows through the switch due to the inrush current during charging in the capacitor provided in the inverter circuit. The switch may be a switch having such a property that switching from the off state to the on state is accelerated by supplying such a large current. With such a switch, carrier movement is smoother than in a configuration in which no capacitor is provided. For example, a transistor such as a MOSFET (field effect transistor) or reverse blocking insulated gate bipolar transistor, or a thyristor such as a GTO (Gate Turn Off Thyristor) (withstand voltage of about 4500 V) having a high breakdown voltage may be used as a switch. The IGBT is excellent in the response speed of the switch. However, as described above, the response speed can be adjusted by the action of the capacitor. Therefore, even when a switch other than the IGBT is used, the response speed of a plurality of switches. It is possible to increase and match.
In the first and second embodiments, the present invention is applied to a three-phase inverter device. However, the present invention is applied to a single-phase or two-phase inverter device or a multi-phase inverter device. You can also. In addition, the circuit configuration of the inverter device is not limited to that described in the embodiment, and a plurality of IGBTs that function as switches are connected in series between the DC current supply source and the connection end. That's fine.

Further, instead of the capacitor in the switch circuit, a capacitive element such as a variable capacitance diode may be used. In short, the charge starts to be stored when the input control signal is switched from “L” to “H”, and when the control signal is switched from “H” to “L”, the stored charge is released. In the case of a capacitive element that behaves like a capacitor, the inrush current at the time of starting to store electric charge instantaneously increases, so that the response speed of the switch can be increased.
In the inverter system according to the second embodiment, the potential detection devices 50 and 60 and the booster device 4 may be inside or outside the inverter device, and the control device 10a performs the control as described in the embodiment. Any configuration can be used. In addition, a power supply unit in which the power source 2 and the booster 4 are integrated may be used. Instead of using the booster 4, it is possible to supply an adjustment current as an output current instead of the power source 2. A variable power supply device may be used.

  Further, the load 3 connected to the inverter is not limited to the dynamometer described above. For example, in driving an electric vehicle, it is necessary to be able to freely control the motor torque regardless of the number of rotations. Therefore, the inverter device controls the electric vehicle by the inverter control if the magnitude and frequency of the alternating current are changed in order to control the torque and rotation speed of the motor for driving the electric vehicle of the load 3 in accordance with the control command. Can be driven. In this case, the power source 2 that is a DC current supply source corresponds to a storage battery. It can also be applied to large-scale transportation (electric railways, monorails, etc.) and unpowered power supply units (UPS). As the load 3, various motors in industrial machines and household equipment, inverter devices, etc. Any device may be used as long as it is operated by receiving AC power supplied from.

It is a circuit diagram which shows the structure of the inverter system in 1st Embodiment of this invention. It is a circuit diagram which shows the structure of the inverter apparatus of the same embodiment. (A) is a figure which shows the time chart which showed a mode that a control apparatus outputs a control signal, (b) is a figure which shows the time chart which showed the mode of the transition of the gate current which flows into the gate of IGBT. . It is a figure explaining the mode of the gate current which flows into the switch circuit in each time and period. It is the graph which showed roughly the relationship between the electrostatic capacitance of a capacitor | condenser, and the response speed of IGBT. It is the circuit diagram which showed the structure of the inverter system in 2nd Embodiment of this invention. It is a circuit diagram which shows the structure of the inverter apparatus of the same embodiment. It is a time chart explaining turn-on time about several IGBT in an inverter circuit. It is a circuit diagram of the switch circuit which employ | adopted the structure which the total of the capacity | capacitance of the capacitor | condenser in a modification changes. It is a circuit diagram which shows the structure of the conventional inverter system. It is a circuit diagram which shows the structure of the conventional inverter apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,1a ... Inverter device, 10, 10a ... Control device, 2 ... Power supply, 20, 20a, 20U, 20Ua, 20V, 20Va, 20W, 20Wa ... Inverter, 3 ... Load, 30, 30a, 40, 40a, ... Inverter Circuit, 31, 35, 41, 45 ... resistor, 32, 36, 42, 46, 32a, 42a ... capacitor, 32b ... capacitor part. 33, 37, 43, 47 ... IGBT, 34, 38, 44, 48 ... diode, 4 ... booster, 50, 60 ... potential detector.

Claims (4)

First and second inverter circuits each having a plurality of switch circuits,
Each of the switch circuits
One end and the other end, and a resistance to which a high level or low level potential control signal is input to the one end;
A capacitive element having one end and the other end, connected in parallel with the resistor, wherein the control signal is input to the one end, and the potential of the input control signal is switched from a low level to a high level. And when the electric potential of the control signal is switched from a high level to a low level, a capacitive element that discharges the stored charge,
Provided between a DC current supply source and a load, connected to the other end of the resistor and the other end of the capacitive element, and supplied from the other end of the resistor and the other end of the capacitive element A switch that is conductive when the potential of the control signal is high, and that is non-conductive when the potential of the control signal supplied from the other end of the resistor and the other end of the capacitive element is low. ,
Between the one pole of the supply source and the load, the switches included in each of the plurality of switch circuits of the first inverter circuit are connected in series,
Between the other pole of the supply source and the load, the switch included in each of the plurality of switch circuits of the second inverter circuit is connected in series. The switch is an insulated gate bipolar transistor;
When the gate of the insulated gate bipolar transistor is connected to the other end of the resistor and the other end of the capacitive element, respectively, and the potential of the control signal supplied to the gate is high, the collector of the insulated gate bipolar transistor The inverter according to claim 1, wherein the inverter is brought into a conductive state. An inverter according to any one of claims 1 and 2,
When supplying the control signal having a high level potential to the plurality of switches included in the first inverter circuit via the resistor and the capacitive element, the plurality of switches included in the second inverter circuit The control signal having a low level potential is supplied via the resistor and the capacitive element, and the control signal having a high level potential is supplied to the switch of the second inverter via the resistor and the capacitive element. Control means for supplying the control signal having a low level potential to the plurality of switches provided in the first inverter via the resistor and the capacitive element. . The capacitive elements of the plurality of switch circuits included in the first and second inverter circuits are one or a plurality of capacitive elements in which the sum of the capacitances changes,
Period specifying means for specifying a difference between the respective periods from when the high-level control signal is supplied by the control means until each of the switches included in the inverter circuit to which the control signal is supplied;
When the difference between the periods specified by the period specifying means is large, the total sum of the capacitances of the one or more capacitive elements in the plurality of switch circuits including the respective switches is set so that the difference becomes small. The inverter device according to claim 3, further comprising: a capacity control unit that changes the capacity.

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