JP6500706B2 - Discharge device - Google Patents

Description

  The present invention relates to a discharge device for discharging a smoothing capacitor that smoothes a voltage supplied to a power conversion circuit.

  BACKGROUND In recent years, an electric vehicle such as an electric car or a hybrid car that travels by driving a motor using electric power stored in a power supply device has been used. In these electrically powered vehicles, generally, between the power supply device and the motor, there are a boost circuit for boosting the output voltage of the power supply device and an inverter circuit for converting the output power of the power supply device which is a DC power supply into alternating current. It is provided. And, on the input side of the booster circuit and the input side of the inverter circuit, smoothing capacitors for stabilizing the input voltage are provided.

  In order to improve the safety of the vehicle, it is necessary to discharge these smoothing capacitors quickly in the event of a vehicle collision. For example, in order to satisfy the standard defined in Federal Regulation FMVSS (Federal Motor Vehicle Safety Standard) 305, it is required to set the voltage across terminals of the smoothing capacitor to a predetermined value or less within 5 seconds from the collision. As a technique for discharging the charge from the smoothing capacitor, for example, there is a configuration disclosed in Patent Document 1.

JP, 2014-217182, A

  Here, Patent Document 1 describes the configuration of a discharge circuit driven using the power stored in the smoothing capacitor. Here, the voltage across terminals of the smoothing capacitor is a very high value (for example, 650 V). Therefore, when driving the discharge switch using the power stored in the smoothing capacitor, a power supply circuit is required to convert the voltage of the power stored in the smoothing capacitor into a voltage suitable for driving the discharge switch.

  Since a very high voltage is input to the power supply circuit from the smoothing capacitor, it is necessary to use a semiconductor switch with a high withstand voltage or to connect a plurality of semiconductor switching elements in series. A high withstand voltage semiconductor switching element has a large size, and when a plurality of semiconductor switching elements are connected in series, it is necessary to secure an insulation distance between the semiconductor switching elements. This causes a problem that the overall size of the circuit is increased.

  The present invention has been made in view of the above problems, and in a configuration in which the discharging of the smoothing capacitor is performed using the power of the smoothing capacitor for smoothing the voltage supplied to the power conversion circuit, the device The main purpose is to reduce the physique.

  The first configuration includes a series connection of switching elements (Sup, Svp, Swp) on the high voltage side and switching elements (Sun, Svn, Swn) on the low voltage side, and changes the on / off state of the switching elements Power conversion circuit (20) for converting DC power supplied from the DC power supply (10) into AC power, and the power conversion circuit is provided between the power conversion circuit and the DC power supply, and is supplied to the power conversion circuit Applied to a power conversion system including a smoothing capacitor (C) for smoothing a voltage to be supplied, a power supply circuit (32) and a discharge switch (SW), and the discharge using the power output from the power supply circuit A discharge circuit (3) which discharges the voltage between the terminals of the smoothing capacitor to a predetermined voltage or less by driving a switch and discharging the charge accumulated in the smoothing capacitor And a plurality of voltage dividing capacitors (C1 to C3, C1a to C3a, C1e to C4e) connected in series, a voltage dividing circuit using the smoothing capacitor as a voltage source and dividing the voltage using the plurality of voltage dividing capacitors (50, Ca, 50e), and the voltage dividing circuit is a discharge device characterized in that the power divided by using the plurality of voltage dividing capacitors is supplied to the power supply circuit.

  According to the above configuration, the smoothing capacitor can be discharged without receiving power supply from the outside. Further, power obtained by dividing the output voltage of the smoothing capacitor by the voltage dividing capacitor is supplied to the power supply circuit of the discharge circuit. Therefore, the voltage input to the power supply circuit is reduced, so that the configuration of the power supply circuit can be simplified and the size of the discharge circuit can be reduced.

  The second configuration includes a series connection of switching elements (Sup, Svp, Swp) on the high voltage side and switching elements (Sun, Svn, Swn) on the low voltage side, and changes the switching state of the switching elements. Power conversion circuit (20) for converting direct current power supplied from the direct current power supply (10) into alternating current power, and provided between the power conversion circuit and the direct current power supply; Power, and a smoothing capacitor (C) provided between the power conversion circuit and the boost circuit to smooth the voltage supplied to the power conversion circuit Applied to a conversion system, the booster circuit includes a booster circuit capacitor (CD) that smoothes a voltage input from the DC power supply, and a power supply circuit (32) and a discharge switch (SW) The discharge switch is driven using the power output from the power supply circuit to discharge the charge stored in the smoothing capacitor, thereby discharging the voltage across the smoothing capacitor to a predetermined voltage or less A voltage divider circuit including a discharge circuit (30) and a plurality of voltage dividing capacitors connected in series, wherein the booster circuit capacitor is used as a voltage source, and the voltage dividing circuit divides the voltage using the plurality of voltage dividing capacitors; The circuit is a discharge device characterized in that the power divided by using the plurality of voltage dividing capacitors is supplied to the power supply circuit.

  According to the above configuration, the smoothing capacitor can be discharged without receiving power supply from the outside. Further, power obtained by dividing the output voltage of the smoothing capacitor by the voltage dividing capacitor is supplied to the power supply circuit of the discharge circuit. Therefore, the voltage input to the power supply circuit is reduced, so that the configuration of the power supply circuit can be simplified. Further, since the voltage across the booster circuit capacitor is lower than the voltage across the smoothing capacitor, the voltage input to the power supply circuit is further reduced as compared to the configuration in which the voltage across the smoothing capacitor is divided. Can. This makes it possible to reduce the size of the discharge circuit.

The electric block diagram showing the power conversion system in a prior art. The electric block diagram showing the power conversion system in a 1st embodiment. The electric block diagram showing the power conversion system in a 2nd embodiment. The electric block diagram showing the power conversion system in 3rd Embodiment. The electric block diagram showing the power conversion system in 4th Embodiment. The electric block diagram showing the power conversion system in 5th Embodiment. The electrical block diagram showing the power conversion system in a modification.

First Embodiment
Hereinafter, a first embodiment in which a discharge device applied to a power conversion system is applied to a power conversion system of a hybrid vehicle will be described with reference to the drawings.

  FIG. 1 shows a system configuration in the prior art. The motor generator 11 is a vehicle-mounted main machine, and is mechanically coupled to drive wheels. Motor generator 11 is connected to battery 10 via inverter circuit 20 (power conversion circuit) and relay SMR. Here, the battery 10 (DC power supply) has a high voltage of, for example, 600 V between its terminals. Further, a smoothing capacitor C is provided between the input terminal of the inverter circuit 20 and the relay SMR so as to be connected in parallel with the battery 10. Note that, instead of the battery 10 as a DC power supply, a booster circuit that boosts the output voltage of the battery may be used.

  The inverter circuit 20 is configured by connecting in series three series connected bodies (legs) of switching elements Sjp (j = u, v, w) on the high voltage side and switching elements Sjn on the low voltage side. The connection point between the high voltage side switching element Sjp and the low voltage side switching element Sjn is connected to each phase of the motor generator 11. The inverter circuit 20 converts DC power supplied from the battery 10 into AC power by changing the on / off states of the switching elements Sjp and Sjn.

  Between the input / output terminals (between the collector and the emitter) of each of the switching element Sjp on the high voltage side and the switching element Sjn on the low voltage side, a reflux diode Djp on the high voltage side and a reflux diode on the low voltage side. The cathode and the anode of Djn are connected. Each of the switching elements Sjp and Sjn is a voltage control type switching element, and more specifically, is constituted by an insulated gate bipolar transistor (IGBT).

  The control device 40 is an electronic control device using a low voltage battery (not shown) as a power supply. The controller 40 operates the inverter circuit 20 to control the motor generator 11 as a control target. Specifically, control device 40 controls operation signals gjp and gjn for operating switching elements Sjp and Sjn for each of U phase, V phase and W phase of inverter circuit 20 based on detection values of various sensors (not shown). Generate and output. Under the control of the control device 40, the switching elements Sjp and Sjn are operated by the control device 40 via a drive unit connected to their conduction control terminals (gates).

  The power conversion system further includes a series connection of a resistance element Ra and a switch SW (discharge switch), and discharges the charge of the smoothing capacitor C to discharge the voltage across the smoothing capacitor C to a predetermined voltage or less. A discharge circuit 30f is provided. A series connected body of the resistance element Ra and the switch SW is connected in parallel to the smoothing capacitor C. The switch SW is a voltage control type switching element, and specifically, is an insulated gate bipolar transistor (IGBT), and is driven by the gate driver 31.

  The control device 40 determines the collision of the vehicle based on the detection value of the acceleration detection sensor which detects the acceleration based on the force acting on itself. Then, when a collision is determined, an abnormal-time discharge command is output to the gate driver 31 in order to forcibly discharge the smoothing capacitor C. Also, when a collision is determined, the control device 40 turns off the relay SMR.

  Here, the gate driver 31 is driven by a voltage generated by the power supply circuit 32 f which is a constant voltage source. The configuration and operation of the power supply circuit 32f will be described below. The power supply circuit 32f includes a series connection of resistance elements R1f to R4f and a Zener diode DT, and a series connection of resistance elements Rb, switches M1f to M4f, and a capacitor Cb. Specifically, switches M1f to M4f are N channel MOS-FETs.

  Furthermore, the gate of the switch M1f is connected to the connection point between the resistive element R1f and the resistive element R2f, and the gate of the switch M2f is connected to the connection point between the resistive element R2f and the resistive element R3f. The gate of the switch M3f is connected to the connection point with the resistance element R4f, and the gate of the switch M4f is connected to the connection point between the resistance element R4f and the cathode of the Zener diode DT.

  When a voltage is input from the smoothing capacitor C to the power supply circuit 32 f, all the switches M1 f to M4 f are turned on. The breakdown voltage of the Zener diode DT of 15 V is applied between the gate and the source of the switch M4f. Assuming that the threshold voltage Vth of the switch M4f is about 3 V, a voltage of about 12 V is applied to the gate driver 31 which is a load. Assuming that the direct current resistance component of the gate driver 31 at the time of driving is about 1.7 kΩ, a current of about 7 mA is input to the gate driver 31, and the gate driver 31 can be driven.

  A voltage (about 158.8 V) obtained by equally dividing the value obtained by subtracting 15 V which is the breakdown voltage of the Zener diode DT from the voltage 650 V between the terminals of the smoothing capacitor C is applied to each resistance element R1 to R4. Here, by setting the resistance value of each of the resistance elements R1f to R4f to be large (for example, 200 kΩ), the flow of a large current from the smoothing capacitor C to the resistance elements R1f to R4f is suppressed to reduce power loss. ing.

  Further, the same voltage (about 158.8 V) as that applied to the resistance elements R2 and R3 is applied between the drain and source of the switches M2f to M4f. The sum of the voltage applied to the resistive element R1f and the voltage between the gate and source of the switch M1f is applied to the drain-source of the switch M1f and to the resistive element Rb. Further, since a current (about 7 mA) having the same value as that of the load flows in the resistance element Rb, a voltage of 0.7 V is applied to the resistance element Rb. For this reason, a voltage of about 161.1 V is applied between the gate and the source of the switch M1f.

  That is, substantially equal voltages are applied to the switches M1 f to M4 f. As described above, by connecting the switches M1 f to M4 f in series, the drain-source voltage of each of the switches M1 f to M4 f is divided, and the withstand voltage required of each of the switches M1 f to M4 f is reduced.

  Here, since the voltage across terminals of the smoothing capacitor C is large, as in the configuration shown in FIG. 1, in the power supply circuit 32 f, it is necessary to divide the voltage using a plurality of switches M1 f to M4 f or to use a switch with a large withstand voltage. . For this reason, the physique as an apparatus increases. In the present embodiment, in order to suppress the increase in the physical size, the voltage across the terminals of the smoothing capacitor C is divided in advance using a voltage dividing circuit, and is output to the power supply circuit.

  The configuration of this embodiment is shown in FIG. The same components as those shown in FIG. 1 are denoted by the same reference numerals, and the description will not be repeated. In the configuration of the present embodiment, a voltage dividing circuit 50 is provided in parallel with the smoothing capacitor C. The voltage dividing circuit 50 includes a series connection of three capacitors C1 to C3. The voltage dividing circuit 50 uses the smoothing capacitor C as a voltage source, and divides the voltage across the terminals of the smoothing capacitor C. Here, a “discharge device” is configured by the discharge circuit 30 and the voltage dividing circuit 50. In the power supply circuit 32, voltage division is performed in the resistance elements R1 and R2 and the switches M1 and M2, as in the power supply circuit 32f (FIG. 1). The switches M1 and M2 are N channel MOS-FETs.

  And voltage output is implemented from the voltage dividing capacitors C2 other than both ends among the voltage dividing capacitors C1 to C3 connected in series. Specifically, both terminals of the voltage dividing capacitor C2 are connected to the power supply circuit 32. With such a configuration, the voltage output from the voltage dividing circuit 50 becomes high when a short circuit failure occurs in the voltage dividing capacitors C1 and C3 other than the voltage dividing capacitor C2 used for voltage output. Can be suppressed.

  Further, among the capacitances of the capacitors C1 to C3, the capacitance of the voltage dividing capacitor C2 is set to be the largest. Thus, the voltage across the terminals of the voltage dividing capacitor C2 is the lowest among the voltages across the capacitors C1 to C3, so the output voltage of the voltage dividing circuit 50 can be further reduced.

  Since the voltage supplied from the voltage dividing circuit 50 to the power supply circuit 32 is divided in advance, in the power supply circuit 32, the withstand voltage required for the switches M1 and M2 is reduced. Therefore, the size of the switches M1 to M2 used for the power supply circuit 32 can be reduced, and the number of switches M1 to M2 used in series connection with the power supply circuit 32 can be reduced (for example, four in the configuration of FIG. 1). 2 pieces in the configuration of FIG. 2). This makes it possible to reduce the size of the discharge device.

  In the present embodiment, the series-connected voltage-dividing capacitors C1 to C3 are connected in parallel to the smoothing capacitor C. In this case, the capacitances of the voltage dividing capacitors C1 to C3 may be smaller (for example, several μF) than the capacitance (for example, several hundred μF) of the smoothing capacitor C. For this reason, compared with the decrease of the physique of the power supply circuit 32, the increase of the physique due to the addition of the voltage dividing capacitors C1 to C3 is small, and the physique as the discharge device can be made smaller.

Second Embodiment
The configuration of the second embodiment is shown in FIG. The same components as those shown in FIG. 2 will be assigned the same reference numerals and descriptions thereof will be omitted as appropriate. The smoothing capacitor Ca in the configuration of the present embodiment is composed of three voltage-dividing capacitors C1a to C3a connected in series. Then, voltage division is performed using a voltage dividing capacitor C2a that is a voltage dividing capacitor other than the voltage dividing capacitors C1a and C3a at both ends, and power output to the power supply circuit 32 is performed.

  That is, the smoothing capacitor Ca of the present embodiment is configured of a plurality of voltage dividing capacitors C1a to C3a connected in series, and doubles as a voltage dividing circuit. Then, the voltage across the terminals of the smoothing capacitor Ca is divided by using a plurality of voltage dividing capacitors C1a to C3a. In this configuration, since it is not necessary to add a voltage dividing capacitor in addition to the smoothing capacitor, the physique as a discharge device can be efficiently suppressed.

Third Embodiment
The configuration of the third embodiment is shown in FIG. The same components as those shown in FIG. 2 will be assigned the same reference numerals and descriptions thereof will be omitted as appropriate. In the configuration of the present embodiment, the voltage in the power supply circuit 32 is detected by the voltage sensor 41 (voltage detection means). Specifically, the voltage sensor 41 detects the voltage at the connection point between the source of the switch M1 and the drain of the switch M2. Then, the control device 40 as the abnormality determination means determines the abnormality of the voltage dividing circuit 50 based on the detection value of the voltage sensor 41.

  Specifically, when the detection value of the voltage sensor 41 becomes higher than a predetermined first voltage, it is assumed that a short circuit abnormality has occurred in the voltage dividing capacitor C1 on the higher voltage side than the voltage dividing capacitor C2 used for power output. judge. In addition, when the detection value of the voltage sensor 41 becomes lower than a predetermined second voltage, short circuit abnormality occurs in the voltage dividing capacitor C3 on the lower voltage side than the voltage dividing capacitor C2 used for power output, or It is determined that a normally open abnormality has occurred in the voltage dividing capacitor C1 on the higher voltage side than the voltage dividing capacitor C2 used for the output. As described above, according to the configuration of the present embodiment, an abnormality of the voltage dividing circuit 50 can be determined.

Fourth Embodiment
The configuration of the fourth embodiment is shown in FIG. The same components as those shown in FIG. 2 will be assigned the same reference numerals and descriptions thereof will be omitted as appropriate. In the configuration of the present embodiment, the current flowing through the power supply circuit 32 is detected by the current sensor 42 (current detection means). Specifically, the current sensor 42 includes a sense resistor Rs between the resistor element R2 and the zener diode DT, and detects a voltage generated in the sense resistor Rs to detect a current flowing in the zener diode DT. Then, the control device 40 as the abnormality determination means determines the abnormality of the voltage dividing circuit 50 based on the detection value of the current sensor 42.

  Specifically, when the detection value of the current sensor 42 becomes larger than the predetermined first current, it is assumed that a short circuit abnormality has occurred in the voltage dividing capacitor C1 on the higher voltage side than the voltage dividing capacitor C2 used for power output. judge. In addition, when the detection value of the current sensor 42 becomes smaller than the predetermined second current, a short circuit abnormality occurs in the voltage dividing capacitor C3 on the lower voltage side than the voltage dividing capacitor C2 used for power output, or It is determined that a normally open abnormality has occurred in the voltage dividing capacitor C1 on the higher voltage side than the voltage dividing capacitor C2 used for the output.

Fifth Embodiment
The configuration of the fifth embodiment is shown in FIG. The same components as those shown in FIG. 2 will be assigned the same reference numerals and descriptions thereof will be omitted as appropriate. The power conversion system in the present embodiment includes a booster circuit 21 between the inverter circuit 20 and the battery 10 in addition to the inverter circuit 20.

  The booster circuit 21 is a known synchronous rectification type booster chopper circuit, and a capacitor CD (booster circuit capacitor) for smoothing the voltage supplied from the battery 10, a reactor L for storing power, a switch Sp on the high voltage side, A switch Sn on the low voltage side and reflux diodes Dp and Dn connected in parallel to the switches Sp and Sn are provided. The control device 40 boosts the power supplied from the battery 10 by turning on and off the switches Sp and Sn at a predetermined duty, and supplies the boosted power to the inverter circuit 20.

  In the configuration of the present embodiment, a voltage dividing circuit 50d is provided in parallel to the capacitor CD. The voltage dividing circuit 50d includes a series connection of three voltage dividing capacitors C1d to C3d. The two terminals of the voltage dividing capacitor C2 are connected to the power supply circuit 32. The voltage dividing circuit 50d uses a capacitor CD as a voltage source to divide the voltage between terminals of the capacitor CD.

  According to the configuration of the present embodiment, power obtained by dividing the output voltage of the capacitor CD by the voltage dividing capacitors C1 d to C3 d is supplied to the power supply circuit 32 of the discharge circuit 30. Therefore, the voltage input to the power supply circuit 32 is reduced, so that the configuration of the power supply circuit 32 can be simplified. Further, compared with the voltage between terminals of the smoothing capacitor C (the output voltage of the booster circuit 21), the voltage between terminals of the capacitor CD (the input voltage of the voltage booster circuit 21) is lower. Therefore, according to the configuration of the present embodiment, the voltage input to the power supply circuit 32 can be further reduced compared to the configuration in which the voltage across the terminals of the smoothing capacitor C is divided and input to the power supply circuit 32.

(Other embodiments)
As shown in FIG. 7, the voltage dividing circuit 50e includes three or more series-connected voltage dividing capacitors C1e to C4e, and among the voltage dividing capacitors C1e to C4e, two or more voltage dividings on the high voltage side The voltage of the smoothing capacitor C may be divided by using a capacitor C3e in which a capacitor is connected in series. With this configuration, even if a short circuit failure occurs in one of the high voltage side voltage dividing capacitors C1e and C2e, the voltage output from the voltage dividing circuit 50e is prevented from being a high voltage. it can.

  In the above embodiment, the switch SW is turned on to discharge the charge accumulated in the smoothing capacitor C in the discharging resistance element Ra. However, this may be changed. Specifically, the switching element (for example, Sup) on the high voltage side and the switching element (for example, Sun) on the low voltage side of the inverter circuit 20 are used as discharge switches, and both are turned on to achieve smooth The charge accumulated in the capacitor C may be discharged.

  In the power supply circuit 32, the place where the voltage detection in the third embodiment is performed and the place where the current detection in the fourth embodiment may be changed. For example, the power supply circuit 32 may detect a voltage input from the voltage dividing circuit 50 to the power supply circuit 32 or a current input.

  The voltage dividing circuit may be configured to include two series-connected voltage dividing capacitors. The voltage dividing circuit may be configured to include five or more series-connected voltage dividing capacitors. In the voltage dividing circuit, a plurality of voltage dividing capacitors may be connected in series, and the capacitors may be connected in parallel to the voltage dividing capacitors.

  DESCRIPTION OF SYMBOLS 10 ... Battery (DC power supply), 20 ... Inverter circuit (power conversion circuit), 30 ... Discharge circuit, 32 ... Power supply circuit, 50 ... Voltage dividing circuit, C ... Smoothing capacitor, C1-C3 ... Voltage dividing capacitor, SW ... Switch , Sun, Svn, Swn ... switching elements, Sup, Svp, Swp ... switching elements.

Claims (13)

A DC power supply comprising a series connection of switching elements (Sup, Svp, Swp) on the high voltage side and switching elements (Sun, Svn, Swn) on the low voltage side, and changing the on / off state of the switching elements (10) a power conversion circuit (20) for converting DC power supplied from the power supply into AC power;
A booster circuit (21) provided between the power conversion circuit and the DC power supply, for boosting a voltage supplied from the DC power supply;
A smoothing capacitor (C) provided between the power conversion circuit and the booster circuit, for smoothing the voltage supplied to the power conversion circuit;
Applied to a power conversion system comprising
The booster circuit includes a booster circuit capacitor (CD) that smoothes a voltage input from the DC power supply,
The smoothing capacitor includes a power supply circuit (32) and a discharge switch (SW), and uses the power output from the power supply circuit to drive the discharge switch to discharge the charge stored in the smoothing capacitor. A discharge circuit (30) for discharging the voltage across the terminals of the
A voltage dividing circuit (50d) including three or more voltage-dividing capacitors (C1d to C3d) connected in series, wherein the booster circuit capacitor is a voltage source and voltage is divided using the three or more voltage-dividing capacitors;
The voltage dividing circuit is provided with ones having different capacities as the voltage dividing capacitors, and supplies divided power using the one with the largest capacity among the three or more voltage dividing capacitors to the power supply circuit. Discharge device. A DC power supply comprising a series connection of switching elements (Sup, Svp, Swp) on the high voltage side and switching elements (Sun, Svn, Swn) on the low voltage side, and changing the on / off state of the switching elements (10) a power conversion circuit (20) for converting DC power supplied from the power supply into AC power;
A booster circuit (21) provided between the power conversion circuit and the DC power supply, for boosting a voltage supplied from the DC power supply;
A smoothing capacitor (C) provided between the power conversion circuit and the boosting circuit, for smoothing the boosted voltage supplied to the power conversion circuit;
Applied to a power conversion system comprising
The boosting circuit includes a boosting circuit capacitor (CD) that smoothes the voltage before the boosting input from the DC power supply,
The smoothing capacitor includes a power supply circuit (32) and a discharge switch (SW), and uses the power output from the power supply circuit to drive the discharge switch to discharge the charge stored in the smoothing capacitor. A discharge circuit (30) for discharging the voltage across the terminals of the
A voltage divider circuit including a plurality of voltage dividing capacitors (C1d to C3d) connected in series, the voltage boosting circuit capacitor for smoothing the voltage before boosting being a voltage source, and voltage division using the plurality of voltage dividing capacitors ( And 50d),
The discharge is characterized in that the voltage dividing circuit supplies the power divided by using the plurality of voltage dividing capacitors to the power supply circuit, and discharges the smoothing capacitor for smoothing the boosted voltage. apparatus. The voltage dividing circuit includes three or more voltage dividing capacitors, and among the voltage dividing capacitors, the power divided by using one other than both ends (C2) is supplied to the power supply circuit. The discharge device according to item 1 or 2 . The voltage dividing circuit includes ones having different capacities as the voltage dividing capacitors, and supplies power divided by using the voltage dividing capacitor having the largest capacity (C2) to the power supply circuit. The discharge device according to claim 2 or 3 . The voltage dividing circuit (50e) includes three or more voltage dividing capacitors (C1e to C4e), and among the voltage dividing capacitors, one in which two or more voltage dividing capacitors are connected in series on the high voltage side (C3e The discharge device according to any one of claims 1 to 4 , wherein the power divided by using V.) is supplied to the power supply circuit. A voltage detection means (41) for detecting the voltage of the power supply circuit;
The discharge device according to any one of claims 1 to 5 , further comprising abnormality determination means (40) for determining an abnormality of the voltage dividing capacitor based on a value detected by the voltage detection means. When the detection value by the voltage detection means becomes higher than a predetermined first voltage, the abnormality determination means causes a short circuit abnormality in the voltage division capacitor on the higher voltage side than the voltage division capacitor used for power output. The discharge device according to claim 6 , which is determined to be present. When the detection value by the voltage detection means becomes lower than a predetermined second voltage, the abnormality determination means causes a short circuit abnormality in the voltage division capacitor on the lower voltage side than the voltage division capacitor used for power output. The discharge device according to claim 6 or 7 , wherein it is determined that an open abnormality has occurred in the voltage dividing capacitor on the higher voltage side than the voltage dividing capacitor used for power output. And current detection means for detecting the current flowing in the power supply circuit,
The discharge device according to any one of claims 1 to 8 , further comprising: abnormality determination means for determining an abnormality of the voltage dividing capacitor based on a value detected by the current detection means. A DC power supply comprising a series connection of switching elements (Sup, Svp, Swp) on the high voltage side and switching elements (Sun, Svn, Swn) on the low voltage side, and changing the on / off state of the switching elements (10) a power conversion circuit (20) for converting DC power supplied from the power supply into AC power;
Smoothing capacitors (C, Ca) which are provided between the power conversion circuit and the DC power supply and which smooth the voltage supplied to the power conversion circuit;
Applied to a power conversion system comprising
The smoothing capacitor includes a power supply circuit (32) and a discharge switch (SW), and uses the power output from the power supply circuit to drive the discharge switch to discharge the charge stored in the smoothing capacitor. A discharge circuit (30) for discharging the voltage across the terminals of the
A voltage dividing circuit (50, comprising a plurality of voltage dividing capacitors (C1 to C3, C1a to C3a, C1e to C4e) connected in series, the smoothing capacitor being a voltage source, and voltage division using the plurality of voltage dividing capacitors Ca, 50e),
Equipped with
The voltage dividing circuit supplies power divided by using the plurality of voltage dividing capacitors to the power supply circuit.
And current detection means for detecting the current flowing in the power supply circuit,
A discharge device comprising abnormality determination means for determining an abnormality of the voltage dividing capacitor based on a value detected by the current detection means. A DC power supply comprising a series connection of switching elements (Sup, Svp, Swp) on the high voltage side and switching elements (Sun, Svn, Swn) on the low voltage side, and changing the on / off state of the switching elements (10) a power conversion circuit (20) for converting DC power supplied from the power supply into AC power;
A booster circuit (21) provided between the power conversion circuit and the DC power supply, for boosting a voltage supplied from the DC power supply;
A smoothing capacitor (C) provided between the power conversion circuit and the booster circuit, for smoothing the voltage supplied to the power conversion circuit;
Applied to a power conversion system comprising
The booster circuit includes a booster circuit capacitor (CD) that smoothes a voltage input from the DC power supply,
The smoothing capacitor includes a power supply circuit (32) and a discharge switch (SW), and uses the power output from the power supply circuit to drive the discharge switch to discharge the charge stored in the smoothing capacitor. A discharge circuit (30) for discharging the voltage across the terminals of the
And a voltage dividing circuit (50d) including a plurality of voltage dividing capacitors (C1d to C3d) connected in series, the voltage boosting circuit capacitor serving as a voltage source, and voltage dividing using the plurality of voltage dividing capacitors.
The voltage dividing circuit supplies power divided by using the plurality of voltage dividing capacitors to the power supply circuit.
And current detection means for detecting the current flowing in the power supply circuit,
A discharge device comprising abnormality determination means for determining an abnormality of the voltage dividing capacitor based on a value detected by the current detection means. When the detection value by the current detection means becomes larger than a predetermined first current, the abnormality determination means causes a short circuit abnormality in the voltage division capacitor on the higher voltage side than the voltage division capacitor used for power output. The discharge device according to any one of claims 9 to 11 , which is determined to be present. When the detection value by the current detection means becomes smaller than a predetermined second current, the abnormality determination means causes a short circuit abnormality in the voltage division capacitor on the lower voltage side than the voltage division capacitor used for power output. It is determined that an open abnormality has occurred in the voltage dividing capacitor on the higher voltage side than the voltage dividing capacitor used for power output, according to any one of claims 9 to 12 . Discharge device.

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