WO2023181166A1

WO2023181166A1 - Power conversion device

Info

Publication number: WO2023181166A1
Application number: PCT/JP2022/013476
Authority: WO
Inventors: 一真藤原
Original assignee: 三菱電機株式会社
Priority date: 2022-03-23
Filing date: 2022-03-23
Publication date: 2023-09-28

Abstract

This power conversion device comprises: a power conversion circuit that is connected to a DC power supply via a switch; a smoothing capacitor that is connected between the power supply line and the ground line of the power conversion circuit; a charge pump circuit that has a charge pump capacitor; a drive circuit that drives power semiconductor elements; a voltage detection circuit that detects the voltage of the smoothing capacitor; and a control circuit. The charge pump circuit can perform an operation for causing the charge pump capacitor to alternately connect to the power supply line and the ground line. The control circuit is configured so as to cause the charge pump circuit to perform a discharging operation in which the charge pump capacitor is alternately connected to the power supply line and the ground line after the switch is brought into an open state and to stop the discharging operation of the charge pump circuit when the voltage of the smoothing capacitor becomes less than or equal to a threshold voltage or when an elapsed time from the start of the discharging operation exceeds a threshold time.

Description

power converter

The present disclosure relates to a power conversion device having a smoothing capacitor.

Patent Document 1 describes a generator motor drive device. This generator motor drive device includes a generator motor, a capacitor, a driver, a booster, and a controller. The controller performs discharge control when an instruction is input. In the discharge control, the controller operates the booster and the driver, and performs control to discharge the power stored in the capacitor using the generator motor as a load. When the voltage across the capacitor reaches a threshold, the controller continues to turn on the switching element of the booster to form a closed circuit including the capacitor. As a result, the power stored in the capacitor is discharged, and the voltage between the terminals of the capacitor reaches a voltage value close to the zero level.

Patent No. 5529393

In the generator motor drive device described above, the charge in the capacitor is discharged by driving the inverter circuit of the booster. Therefore, when discharging the charge of the capacitor, both the plurality of semiconductor elements that constitute the inverter circuit and the load of the generator motor need to be in a normal state. Therefore, if any one of these semiconductor elements and the generator motor becomes abnormal, there is a problem in that the charge in the capacitor cannot be discharged.

The present disclosure has been made to solve the above-mentioned problems, and aims to provide a power conversion device that can more reliably discharge the residual charge of a smoothing capacitor.

A power conversion device according to the present disclosure has a power semiconductor element connected in a bridge manner, and is connected between a power conversion circuit connected to a DC power source via a switch, and a power line and a ground line of the power conversion circuit. a charge pump circuit having a plurality of charge pump capacitors, a drive circuit that drives the power semiconductor element using electric power generated by the charge pump circuit, and a voltage of the smoothing capacitor. and a control circuit, the charge pump circuit operating to alternately connect at least one charge pump capacitor among the plurality of charge pump capacitors to the power supply line and the ground line. The control circuit may cause the charge pump circuit to perform a discharging operation in which the at least one charge pump capacitor is alternately connected to the power supply line and the ground line after the switch is in an open state. and when the voltage of the smoothing capacitor becomes equal to or less than a threshold voltage, or when the elapsed time from the start of the discharging operation exceeds a threshold time, the discharging operation of the charge pump circuit is stopped. It is configured to allow

According to the present disclosure, residual charges in the smoothing capacitor can be discharged more reliably.

1 is a diagram showing a schematic configuration of a power conversion device according to Embodiment 1. FIG. FIG. 3 is a diagram illustrating a discharging operation in the power conversion device according to the first embodiment. 5 is a flowchart showing the flow of discharge processing in the power conversion device according to the first embodiment.

Embodiment 1.
A power conversion device according to Embodiment 1 will be described. FIG. 1 is a diagram showing a schematic configuration of a power conversion device according to this embodiment. In this embodiment, a power conversion device 14 used in a mechanical and electrical integrated generator motor for vehicles will be described as an example.

As shown in FIG. 1, the power conversion device 14 includes a power conversion circuit 7, a charge pump circuit 8, a drive circuit 6, a control circuit 10, and a voltage detection circuit 11. The power conversion device 14 is configured to operate the generator motor 12. The generator motor 12 is a rotating part of a mechanical and electrically integrated generator motor that serves as an auxiliary machine for an automobile.

The power conversion circuit 7 is connected to the first DC power supply 1 via the power supply line 1a and the first switch 3. The first DC power supply 1 is provided outside the power conversion device 14. The first switch 3 is provided on the power supply line 1a. The first switch 3 performs opening and closing operations based on commands from an electronic control unit (ECU) 13. When the first switch 3 is in the closed state, DC power is supplied from the first DC power supply 1 to the power conversion circuit 7 via the power supply line 1a. When the first switch 3 is in the open state, the power supply from the first DC power supply 1 to the power conversion circuit 7 is cut off.

The power conversion circuit 7 has a plurality of power semiconductor elements 9. The plurality of power semiconductor elements 9 are bridge-connected between the power supply line 1a and the ground line 1b. The power conversion circuit 7 is configured to generate necessary output power by switching operations of each power semiconductor element 9. When driving the electric motor, the power conversion circuit 7 converts DC power supplied from the first DC power supply 1 into AC power. The converted AC power is supplied to the generator motor 12. During power generation, the power conversion circuit 7 rectifies alternating current power supplied from the generator motor 12 and converts it into direct current.

The drive circuit 6 is configured to drive the plurality of power semiconductor elements 9 of the power conversion circuit 7 based on commands from the control circuit 10. The drive circuit 6 is provided for each phase of the generator motor 12.

A smoothing capacitor 5 is connected between the power supply line 1a and the ground line 1b. The smoothing capacitor 5 has a function of smoothing ripple voltage generated during power conversion. The smoothing capacitor 5 preferably has a low equivalent series resistance (ESR) and a relatively large capacitance. For example, as the smoothing capacitor 5, an electrolytic capacitor or the like is used.

The charge pump circuit 8 is configured to generate power for driving the power semiconductor element 9. The charge pump circuit 8 has a configuration in which a capacitor, a diode, and a switch are combined. In the charge pump circuit 8, the switch is alternately switched between the power supply side and the ground side, thereby raising the lower end voltage and boosting the output voltage. The driving power generated by the charge pump circuit 8 is supplied to each power semiconductor element 9 via the driving circuit 6.

The charge pump circuit 8 includes a low side charge pump capacitor 8b, a high side charge pump capacitor 8a, a charge pump drive circuit 8c, a switch 8d, and a switch 8e.

The switch 8d is provided corresponding to the high side charge pump capacitor 8a. Switch 8e is provided corresponding to low side charge pump capacitor 8b. The operation of each

switch

8d, 8e is switched by a charge pump drive circuit 8c.

The low-side charge pump capacitor 8b is connected to the power supply line 1c when the switch 8e is switched to the power supply side. Power is supplied to the power supply line 1c from the second DC power supply 2 via the control power generation circuit 15. A second switch 4 is provided between the second DC power supply 2 and the control power generation circuit 15. The second switch 4 performs opening and closing operations based on commands from the ECU 13. When the second switch 4 is in the closed state, power is supplied from the second DC power supply 2 to the control circuit 10 and the power supply line 1c via the control power generation circuit 15. When the second switch 4 is in the open state, power supply to the control circuit 10 and the power supply line 1c is cut off. The low-side charge pump capacitor 8b is connected to the ground line 1b when the switch 8e is switched to the ground side.

The high side charge pump capacitor 8a is connected to the power supply line 1a when the switch 8d is switched to the power supply side. Power is supplied from the first DC power supply 1 to the power supply line 1a. The high side charge pump capacitor 8a is connected to the ground line 1b when the switch 8d is switched to the ground side.

In this way, the charge pump circuit 8 can perform an operation of alternately connecting each of the low side charge pump capacitor 8b and the high side charge pump capacitor 8a to the power supply line and the ground line. The output voltage is boosted by alternately connecting the low-side charge pump capacitor 8b and the high-side charge pump capacitor 8a to the power supply line and the ground line.

On the high side, a voltage that is the sum of the output voltage boosted on the low side and the voltage of the power supply line 1a is output. The high-side output is supplied as driving power to the power semiconductor element 9 of the upper arm via the driving circuit 6. The low-side output is supplied as driving power to the power semiconductor element 9 of the lower arm via the driving circuit 6.

It is desirable that the low-side charge pump capacitor 8b and the high-side charge pump capacitor 8a used for charge pump operation are capable of rapidly transferring and discharging charges. Therefore, it is preferable to use capacitors with low ESR and low equivalent series inductance (ESL) for each of the low-side charge pump capacitor 8b and the high-side charge pump capacitor 8a. For example, a ceramic capacitor or the like is used for each of the low side charge pump capacitor 8b and the high side charge pump capacitor 8a.

In order to alleviate the influence of fluctuations in the second DC power supply 2, it is preferable that power be supplied to each control circuit including the charge pump circuit 8 via the control power generation circuit 15. The control power generation circuit 15 includes a DC/DC converter, a linear regulator, and the like.

The control circuit 10 is configured to control each function of the power conversion device 14. The control circuit 10 mainly operates using electric power supplied from the second DC power supply 2 via the control power generation circuit 15. The control circuit 10 is configured mainly of a microcomputer IC, for example. The control circuit 10 communicates with a higher-level ECU 13 mounted on the vehicle side. In response to an operation request from the ECU 13, the control circuit 10 determines whether the charge pump circuit 8 is allowed to operate, issues commands to the drive control circuit 6a of the drive circuit 6, and the like.

The charge pump circuit 8 and the drive circuit 6 may be functions realized by one IC such as a driver IC. It is only necessary to provide means for permitting and disallowing the respective functions of the charge pump circuit 8 and the drive circuit 6.

The ECU 13 mainly has the role of collecting and controlling information from each sensor of the vehicle. The ECU 13 has a function of commanding the opening and closing operations of the first switch 3 and the second switch 4. When the vehicle is stopped, both the first switch 3 and the second switch 4 are preferably controlled to the open state in order to ensure safety during vehicle maintenance and to prevent the battery from dying due to dark current. In the communication between the ECU 13 and the control circuit 10, information on the state of the vehicle including the open/close states of the first switch 3 and the second switch 4, and information on the state of the power conversion device 14 are exchanged with each other. .

Various power storage devices such as a lead acid battery, a secondary battery, a fuel cell, a capacitor, etc. can be applied to each of the first DC power supply 1 and the second DC power supply 2. The first DC power supply 1 and the second DC power supply 2 are of the same voltage system. Alternatively, the voltage of the first DC power supply 1, which requires relatively large power, is higher than the voltage of the second DC power supply 2. If the voltages of the first DC power supply 1 and the second DC power supply 2 are different, internal insulation may be required. If the smoothing capacitor 5 and charge pump circuit 8 that require discharge have the same grounding system, internal insulation can be achieved by various measures. For example, by using an isolated power supply in the control power generation circuit 15 or by performing insulation treatment between a weak electric system such as the control circuit 10 and a strong electric system such as the charge pump circuit 8 and the drive circuit 6, Internal insulation can be provided.

The voltage detection circuit 11 is configured to detect the voltage of the power line 1a of the first DC power supply 1. Voltage detection circuit 11 is one of the sensors. While the control circuit 10 is operating, the voltage detection circuit 11 can monitor the residual voltage of the smoothing capacitor 5.

FIG. 2 is a diagram illustrating the discharging operation in the power conversion device according to the present embodiment. The charge pump circuit 8 in FIG. 2 has the same connection configuration as the charge pump circuit 8 in FIG. In FIG. 1, low-side charge pump capacitor 8b is alternately connected to power supply line 1c and ground line 1b by switch 8e. The power supply line 1c is connected to the second DC power supply 2 via the control power generation circuit 15. High side charge pump capacitor 8a is alternately connected to power supply line 1a and ground line 1b by switch 8d. The power line 1a is connected to a smoothing capacitor 5. Based on these, the charge pump circuit 8 in FIG. 2 is schematically represented using a variable DC power supply and a variable capacitor.

The drive circuit 6 includes a push-pull circuit 6b and an inverting level shift circuit 6c. The push-pull circuit 6b is configured by connecting two stages of complementary transistors and the like. Push-pull circuit 6b amplifies current to drive power semiconductor element 9. In the example shown in FIG. 2, the power semiconductor element 9 is an N-channel MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor). Further, in the push-pull circuit 6b, an NPN type bipolar transistor is used as an upper stage transistor, and a PNP type bipolar transistor is applied as a lower stage transistor.

In the push-pull circuit 6b, the collector of the upper stage transistor is connected to the output stage of the high side charge pump capacitor 8a. The collector of the lower transistor is connected to the source terminal of the power semiconductor element 9. The midpoint where the emitters of the upper and lower transistors are connected becomes the output stage of the push-pull circuit 6b. The output stage of the push-pull circuit 6b is connected to the gate terminal of the power semiconductor element 9 via a gate resistor.

When a Hi signal is input to the push-pull circuit 6b, the upper stage NPN transistor becomes conductive, and a gate voltage is applied to the power semiconductor element 9 by a push operation. As a result, the power semiconductor element 9 becomes conductive. When the Lo signal is input to the push-pull circuit 6b, the PNP transistor in the lower stage becomes conductive, and the gate and source of the power semiconductor element 9 become at the same potential due to the pull operation. As a result, the power semiconductor element 9 enters the cut-off state.

The level shift circuit 6c has a pull-up resistor 16 and a switching element 17. Pull-up resistor 16 is connected to the output stage of high-side charge pump capacitor 8a. Switching element 17 is connected in series between pull-up resistor 16 and ground line 1b. The output of the level shift circuit 6c is input to the push-pull circuit 6b via a base resistor.

When the switching element 17 becomes conductive, the push-pull circuit 6b performs a pull operation, and the power semiconductor element 9 enters a cut-off state. When the switching element 17 is cut off, the push-pull circuit 6b performs a push operation, and the power semiconductor element 9 becomes conductive.

Therefore, when the operation of the power conversion circuit 7 is stopped, the switching element 17 becomes conductive, and the pull-up resistor 16 is connected to ground. Therefore, the charge on the high-side charge pump capacitor 8a is consumed via the pull-up resistor 16.

Further, when the switch 8d is switched to the power supply side, the consumed charge is supplied from the smoothing capacitor 5 to the high side charge pump capacitor 8a. Since the first switch 3 is in the open state, no charge is supplied to the smoothing capacitor 5 from the first DC power supply 1. Therefore, the smoothing capacitor 5 continues to discharge without being charged. As a result, the capacitor voltage of the smoothing capacitor 5 decreases. In this manner, in this embodiment, the residual charge in the smoothing capacitor 5 is discharged by the discharge operation of the charge pump circuit 8.

Here, it is preferable that the voltage detection circuit 11 has a resistor 11a for voltage division, as shown in FIG. Resistor 11a is connected in series between control circuit 10 and smoothing capacitor 5. As a result, even if the operation of the control circuit 10 is stopped after the discharging process is completed, the charge of the smoothing capacitor 5 is consumed via the resistor 11a. Therefore, the residual charge in the smoothing capacitor 5 can be more completely discharged.

In the present embodiment, the charges in the smoothing capacitor 5 can be discharged by continuing the operation of the charge pump circuit 8 while the power semiconductor element 9 is stopped. Therefore, even if the power conversion circuit 7 or the generator motor 12 is in an abnormal state, the charge in the smoothing capacitor 5 can be discharged. If the power semiconductor element 9 is operated in a state where there is an abnormality in the power conversion circuit 7 or the generator motor 12, there is a risk that a large current will be generated due to a power supply short circuit or the like. In contrast, in the present embodiment, the electric charge in the smoothing capacitor 5 can be discharged more safely because the electric charge can be discharged without operating the power conversion circuit 7.

Next, the procedure of discharge processing in the power conversion device according to the present embodiment will be explained. FIG. 3 is a flowchart showing the flow of discharge processing in the power conversion device according to the present embodiment. The discharging process shown in FIG. 3 is executed by the control circuit 10 when the operation of the power conversion device 14 is stopped.

First, in step S101 in FIG. 3, the control circuit 10 determines whether the first switch 3 is in an open state based on a notification from the higher-level ECU 13. If the first switch 3 is in the open state, the processes from step S102 onwards are executed. If the first switch 3 is in the closed state, the process of step S101 is repeated. Note that the control circuit 10 may start the process of step S101 when receiving a notification from the ECU 13.

In step S102, the control circuit 10 outputs a stop signal to the drive control circuit 6a. As a result, the drive circuit 6 stops driving the power conversion circuit 7, and the power conversion circuit 7 stops operating. Note that, instead of the process in step S102, the control circuit 10 may perform a process to confirm that the drive circuit 6 is in a stopped state.

Next, in step S103, the control circuit 10 calculates the threshold time Tth. Details of the process in step S103 will be described later.

Next, in step S104, the control circuit 10 outputs an operation permission signal to the charge pump circuit 8 that allows the operation of the charge pump circuit 8. As a result, in step S105, the charge pump circuit 8 performs a discharging operation. The residual charge in the smoothing capacitor 5 is gradually discharged by the discharge operation of the charge pump circuit 8. That is, in this embodiment, the smoothing capacitor 5 can be discharged by using the circuit function used in the normal operation of the power conversion device 14. In this embodiment, since there is no need to separately provide a discharge circuit, the configuration of the power converter 14 can be simplified.

Next, in step S106, the control circuit 10 determines whether the elapsed time T since the discharge operation of the charge pump circuit 8 was started exceeds the threshold time Tth. If the elapsed time T exceeds the threshold time Tth, the process of step S107 is executed. If the elapsed time T is less than or equal to the threshold time Tth, the discharge operation of the charge pump circuit 8 is continued.

In step S107, the control circuit 10 determines whether the voltage Vcon of the smoothing capacitor 5 is equal to or lower than the threshold voltage Vth. Voltage Vcon is detected by voltage detection circuit 11. The threshold voltage Vth is set in advance. If the voltage Vcon is less than or equal to the threshold voltage Vth, the process of step S108 is executed. On the other hand, if the voltage Vcon is larger than the threshold voltage Vth, the process of step S109 is executed.

In step S108, the control circuit 10 outputs an operation stop signal to the charge pump circuit 8 to stop the operation of the charge pump circuit 8. As a result, the discharging operation of the charge pump circuit 8 is stopped.

In step S109, the control circuit 10 determines that the first switch 3 is out of order. The failure of the first switch 3 also includes a failure of the control system related to the first switch 3. In other words, if the voltage Vcon does not become equal to or lower than the threshold voltage Vth even though the elapsed time T exceeds the threshold time Tth, the first switch 3 is stuck or the ECU 13 is not able to control the first switch 3 normally. is estimated. When the control circuit 10 determines that the first switch 3 is out of order, it notifies the ECU 13 of information to that effect, for example. This makes it possible to notify the user of the failure of the first switch 3 using a warning light or the like provided in the vehicle.

In this embodiment, it is desirable to calculate the threshold time Tth, which is a variable value, before allowing the charge pump circuit 8 to operate. The voltage applied to the smoothing capacitor 5 varies depending on the state of the first DC power supply 1 and the operation of the power conversion circuit 7. Therefore, the time required for discharging the smoothing capacitor 5 tends to vary.

Therefore, the control circuit 10 estimates the load current or load resistance value in advance. The load current is a current consumed in the charge pump circuit 8 and the drive circuit 6 for all phases in the generator motor 12. The load resistance value is the resistance value of the charge pump circuit 8 and the drive circuit 6 for all phases in the generator motor 12. In step S103, the control circuit 10 determines the voltage Vcon of the smoothing capacitor 5 immediately before performing the discharge process, the load current or load resistance value estimated in advance, and the target value of the voltage Vcon after the discharge process. Calculate the threshold time Tth. The target value of the voltage Vcon after the discharge process is, for example, the threshold voltage Vth. Thereby, it is possible to set an appropriate discharge time that takes into consideration the influence of variations in the voltage Vcon at the time of starting the discharge process. Therefore, the residual charge in the smoothing capacitor 5 can be discharged more reliably, and a failure in the first switch 3 or the control system related to the first switch 3 can be detected with high accuracy.

In the discharge process shown in FIG. 3, the processes in steps S107 and S109 can be omitted. In this case, if the elapsed time T exceeds the threshold time Tth, the control circuit 10 outputs an operation stop signal to the charge pump circuit 8 regardless of the voltage Vcon. Further, in the discharge process shown in FIG. 3, the process of step S106 can be omitted. In this case, the control circuit 10 outputs an operation stop signal to the charge pump circuit 8 regardless of the elapsed time T when the voltage Vcon becomes equal to or lower than the threshold voltage Vth. That is, in the present embodiment, the control circuit 10 outputs an operation stop signal to the charge pump circuit 8 when the voltage Vcon becomes equal to or lower than the threshold voltage Vth, or when the elapsed time T exceeds the threshold time Tth. do.

As explained above, the power conversion device 14 according to the present embodiment includes the power conversion circuit 7, the smoothing capacitor 5, the charge pump circuit 8, the drive circuit 6, the voltage detection circuit 11, and the control circuit 10. It is equipped with. The power conversion circuit 7 includes power semiconductor elements 9 connected in a bridge manner. Power conversion circuit 7 is connected to first DC power supply 1 via first switch 3 . Smoothing capacitor 5 is connected between power supply line 1a of power conversion circuit 7 and ground line 1b. Charge pump circuit 8 has a plurality of charge pump capacitors. Drive circuit 6 drives power semiconductor element 9 using electric power generated by charge pump circuit 8 . The voltage detection circuit 11 detects the voltage of the smoothing capacitor 5. The charge pump circuit 8 can perform an operation of alternately connecting at least one high-side charge pump capacitor 8a among the plurality of charge pump capacitors to the power supply line 1a and the ground line 1b.

After the first switch 3 is opened, the control circuit 10 causes the charge pump circuit 8 to perform a discharging operation in which the high-side charge pump capacitor 8a is alternately connected to the power supply line 1a and the ground line 1b. The control circuit 10 causes the charge pump circuit 8 to discharge when the voltage Vcon of the smoothing capacitor 5 becomes equal to or lower than the threshold voltage Vth, or when the elapsed time T from the start of the discharging operation exceeds the threshold time Tth. It is configured to stop the operation. Here, the first switch 3 is an example of a switch. The first DC power supply 1 is an example of a DC power supply. High side charge pump capacitor 8a is an example of a charge pump capacitor.

According to this configuration, the charge in the smoothing capacitor 5 can be discharged by the discharging operation of the charge pump circuit 8 without operating the power conversion circuit 7. Thereby, the residual charge in the smoothing capacitor 5 can be more reliably discharged without depending on the states of the power conversion circuit 7 and the generator motor 12. Further, since the circuit used in the normal operation of the power converter 14 can be used to discharge without separately providing a dedicated discharge circuit, the configuration of the power converter 14 can be simplified.

In the power conversion device 14 according to the present embodiment, the drive circuit 6 includes an inverting level shift circuit 6c. The level shift circuit 6c includes a switching element 17 and a pull-up resistor 16. The switching element 17 and the pull-up resistor 16 are connected in series between the output stage of the charge pump circuit 8 and the ground line 1b. When the power semiconductor element 9 is in the cut-off state, the switching element 17 is in the conductive state. According to this configuration, when the operation of the power conversion circuit 7 is stopped, the pull-up resistor 16 is connected to the ground via the switching element 17 that is in a conductive state. Therefore, the charge of the high-side charge pump capacitor 8a can be consumed by the pull-up resistor 16.

In the power conversion device 14 according to the present embodiment, the control circuit 10 causes the first switch 3 to malfunction if the voltage Vcon of the smoothing capacitor 5 does not become equal to or lower than the threshold voltage Vth even though the elapsed time T exceeds the threshold time Tth. It is determined that the According to this configuration, it is possible to notify the user of a failure of the first switch 3.

In the power conversion device 14 according to the present embodiment, the control circuit 10 controls the voltage of the smoothing capacitor 5 before the discharge operation is started, the load current consumed in the charge pump circuit 8 and the drive circuit 6, and the threshold value. The threshold time Tth is calculated based on the voltage Vth. According to this configuration, the threshold time Tth can be appropriately set according to the time required for discharge.

In the power conversion device 14 according to the present embodiment, the voltage detection circuit 11 includes a resistor 11a. The resistor 11a is connected in series between the control circuit 10 and the smoothing capacitor 5. According to this configuration, even if the operation of the control circuit 10 is stopped after the discharge process is completed, the charge of the smoothing capacitor 5 is consumed via the resistor 11a. Therefore, the residual charge in the smoothing capacitor 5 can be more completely discharged.

In the above embodiment, a power conversion device used in a mechanical and electrical integrated generator-motor for vehicles is taken as an example, but the present invention is not limited to this. The present disclosure can be applied to various power conversion devices that require discharge processing of a smoothing capacitor.

Note that the embodiments of the present disclosure should be considered to be illustrative in all respects and not limiting, and that various changes may be made without departing from the technical spirit of the present disclosure. Needless to say.

1 First DC power supply, 1a Power line, 1b Ground line, 1c Power line, 2 Second DC power supply, 3 First switch, 4 Second switch, 5 Smoothing capacitor, 6 Drive circuit, 6a Drive control circuit, 6b Push Pull circuit, 6c level shift circuit, 7 power conversion circuit, 8 charge pump circuit, 8a high side charge pump capacitor, 8b low side charge pump capacitor, 8c charge pump drive circuit, 8d switch, 8e switch, 9 power semiconductor element, 10 control Circuit, 11 voltage detection circuit, 11a resistor, 12 generator motor, 13 ECU, 14 power converter, 15 control power generation circuit, 16 pull-up resistor, 17 switching element, T elapsed time, Tth threshold time, Vcon voltage, Vth Threshold voltage.

Claims

a power conversion circuit having bridge-connected power semiconductor elements and connected to a DC power source via a switch;
a smoothing capacitor connected between the power supply line and the ground line of the power conversion circuit;
a charge pump circuit having a plurality of charge pump capacitors;
a drive circuit that drives the power semiconductor element using electric power generated by the charge pump circuit;
a voltage detection circuit that detects the voltage of the smoothing capacitor;
a control circuit;
Equipped with
The charge pump circuit is capable of performing an operation of alternately connecting at least one charge pump capacitor among the plurality of charge pump capacitors to the power supply line and the ground line,
The control circuit includes:
After the switch is in an open state, causing the charge pump circuit to perform a discharging operation in which the at least one charge pump capacitor is alternately connected to the power supply line and the ground line;
The charge pump circuit is configured to stop the discharging operation of the charge pump circuit when the voltage of the smoothing capacitor becomes equal to or less than a threshold voltage, or when the elapsed time from the start of the discharging operation exceeds a threshold time. power conversion equipment.
The drive circuit has an inverting level shift circuit,
The level shift circuit includes a switching element and a pull-up resistor connected in series between the output stage of the charge pump circuit and the ground line,
The power conversion device according to claim 1, wherein when the power semiconductor element is in a cut-off state, the switching element is in a conductive state.
3. The control circuit determines that the switch is malfunctioning if the voltage of the smoothing capacitor does not become equal to or lower than the threshold voltage even if the elapsed time exceeds the threshold time. power converter.
The control circuit determines the threshold time based on the voltage of the smoothing capacitor before the discharge operation is started, the load current consumed in the charge pump circuit and the drive circuit, and the threshold voltage. The power conversion device according to any one of claims 1 to 3, which calculates.
The power conversion device according to any one of claims 1 to 4, wherein the voltage detection circuit includes a resistor connected in series between the control circuit and the smoothing capacitor.