Power conversion device

Abstract

It includes: multiple drive circuits (103U, 103L) that drive multiple switching elements constituting the upper and lower arms respectively; a power supply circuit that supplies power to the multiple drive circuits; and a discharge circuit for discharging capacitors. The power supply circuit includes a first transformer (201U) for the upper arm and a second transformer (201L) for the lower arm, whose primary windings are connected in parallel with a DC power supply. The secondary windings of the first and second transformers supply power to the drive circuits and to the low-voltage circuit (110). The first and second transformers each have a feedback winding that outputs the voltage to the drive circuits to the power control IC, and the discharge circuit (120) is driven by the power supplied from the feedback windings.

Description

Technical Field

[0001] This invention relates to power conversion devices, and more particularly to power conversion devices mounted on electric vehicles. Background Technology

[0002] Electric vehicles such as hybrid electric vehicles have a power conversion device (inverter device) for supplying alternating current to the drive motor. Such a power conversion device operates on power supplied from a high-voltage power source (battery) of tens to hundreds of volts, while the control circuit for controlling the power conversion device operates on a relatively low-voltage power source of around 12 volts.

[0003] Since the gate drive circuit of a power converter using a high-voltage power supply is a high-voltage circuit, it needs to be isolated from the low-voltage circuit. Therefore, the power supply for the gate drive circuit (hereinafter referred to as the GD power supply) is supplied from an insulated power source using a transformer. In a commonly used power converter driving a three-phase AC motor, there are six semiconductor elements with three upper and lower arms. Both the gate drive circuit driving the semiconductor elements and the GD power supply require six arms. In addition, for the loss of low-voltage power supply as one of the fault conditions that should be considered, a backup power supply (hereinafter referred to as BKPS) is also required to supply power from high voltage to low voltage for the safety control operation in order to safely stop the inverter. Furthermore, depending on the situation, when the power converter stops, it is necessary to discharge the high-voltage charge accumulated in the smoothing capacitors in the power converter within a few seconds (active discharge), which also requires an active discharge power supply.

[0004] For example, in Patent Document 1, a method for generating GD power supply is described, which involves simultaneously generating BKPS using a three-phase power supply from a low-voltage power supply on the upper arm and a three-phase power supply from a high-voltage power supply on the lower arm. In the power conversion device of Patent Document 1, even in the event of a loss of low-voltage power supply, a three-phase short-circuit operation, as one of the safety controls, can be performed.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2015-159684 Summary of the Invention

[0008] The problem the invention aims to solve

[0009] To date, configurations have generally been either centralized (using a single transformer to generate all the multiple power sources) or decentralized (using separate transformers and power circuits for each power source). In the centralized configuration, if a low-voltage power loss and a power failure overlap, safety control actions cannot be performed. In the decentralized configuration, even if one of the GD power sources in the six arms fails when a low-voltage power loss occurs, a three-phase short circuit, as a safety control measure, can still be performed. However, if the BKPS fails, power cannot be supplied to the safety control circuit. Active discharge cannot operate if the power source for active discharge fails. In the power conversion device described in Patent Document 1, the control circuit cannot operate even if the lower arm's GD power source fails when a low-voltage power loss occurs, thus preventing the execution of safety control actions.

[0010] The main objective of this invention is to provide a power conversion device that can perform safe control actions even under conditions of low-voltage power loss and overlapping power faults.

[0011] Technical means to solve the problem

[0012] The power conversion device of the present invention is a power conversion device that converts DC power supplied from a DC power source into AC power, comprising: a plurality of switching elements constituting the upper and lower arms of each phase in a three-phase inverter circuit; a plurality of drive circuits that respectively drive the plurality of switching elements; a power supply circuit that supplies power to the plurality of drive circuits; and a discharge circuit for discharging a capacitor connected in parallel with the three-phase inverter circuit, wherein the power supply circuit has a first transformer and a second transformer whose primary windings are connected in parallel with the DC power source, the secondary winding of the first transformer supplies power to the drive circuits that drive the plurality of switching elements constituting the upper arm and supplies power to a low-voltage circuit connected to a low-voltage power source, the secondary winding of the second transformer supplies power to the drive circuits that drive the plurality of switching elements constituting the lower arm and supplies power to the low-voltage circuit, the first transformer and the second transformer each have a feedback winding that outputs a feedback voltage corresponding to the voltage output to the drive circuit to a power control IC, and the discharge circuit is driven by power supplied from the feedback windings of the first transformer and the second transformer.

[0013] The effects of the invention

[0014] According to the present invention, a power conversion device is provided that can perform safe control operations even in the event of low-voltage power loss and power failure overlap. Attached Figure Description

[0015] Figure 1 This is an overall configuration diagram of the power conversion device 100.

[0016] Figure 2 This is a circuit diagram of the gate drive power supply circuits 200U and 200L.

[0017] Figure 3 This is a schematic diagram of the active discharge circuit 120.

[0018] Figure 4 This is a schematic diagram illustrating the configuration of the gate drive power supply circuits 200U and 200L according to an embodiment of the present invention.

[0019] Figure 5 This is a schematic diagram showing the configuration of a centralized gate drive power supply circuit with a high-voltage power supply as input (first comparative example).

[0020] Figure 6 This is a schematic diagram illustrating the configuration of a centralized gate drive power supply circuit with a low-voltage power supply as input (second comparative example).

[0021] Figure 7 This is a schematic diagram illustrating the configuration of a distributed gate drive power supply circuit with a low-voltage power supply as input (third comparative example).

[0022] Figure 8 This is a flowchart of the diagnostic process using existing methods.

[0023] Figure 9 This is a diagnostic flowchart of an embodiment of the present invention. Detailed Implementation

[0024] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The following description and drawings are examples for illustrating the present invention, and appropriate omissions and simplifications have been made for clarity. The present invention can also be implemented in various other ways. Unless otherwise specified, the constituent elements can be singular or plural. For ease of understanding, the positions, sizes, shapes, extents, etc., of the constituent elements shown in the drawings sometimes do not represent actual positions, sizes, shapes, extents, etc. Therefore, the present invention is not limited to the positions, sizes, shapes, extents, etc., disclosed in the drawings. When multiple constituent elements with the same or identical functions exist, different subscripts are sometimes added to the same symbols for description. However, when it is not necessary to distinguish these multiple constituent elements, the subscripts are sometimes omitted for description.

[0025] Figure 1 This is an overall configuration diagram of the power conversion device 100. The power conversion device 100 converts the DC power supplied from the DC power source 901 via the contactor 902 into AC power to drive the motor 900. Additionally, when the motor 900 rotates due to external force, the motor 900 functions as a generator, and the power conversion device 100 converts the AC power into DC power to charge the DC power source 901. The DC power source 901 is, for example, a high-voltage battery.

[0026] The power conversion device 100 includes a motor control circuit 110, an inverter circuit 300, and a voltage smoothing capacitor 500.

[0027] The motor control circuit 110 receives torque commands or rotation commands, etc., from a host controller (not shown) to drive the motor 900. Then, the motor control circuit 110 provides gate drive commands 101U and 101L, corresponding to the commands, to gate drive circuits 103U and 103L via buffer circuits, respectively. Gate drive commands 101U and gate drive circuit 103U correspond to the upper arm of the inverter circuit 300, and gate drive commands 101L and gate drive circuit 103L correspond to the lower arm of the inverter circuit 300.

[0028] Gate drive circuits 103U and 103L output gate drive signals 104U and 104L to drive the switching elements of the upper and lower arms of inverter circuit 300 according to gate drive commands 101U and 101L. Inverter circuit 300 converts the DC power supplied from DC power supply 901 into AC power by driving each switching element according to the gate drive signals 104U and 104L, thereby driving motor 900. Inverter circuit 300 has three switching elements as the upper arm and three switching elements as the lower arm. Additionally, DC power supply 901 supplies DC power to inverter circuit 300 through a bus.

[0029] The gate drive circuit 103U consists of three drive circuits corresponding to the three switching elements of the upper arm. Similarly, the gate drive circuit 103L consists of three drive circuits corresponding to the three switching elements of the lower arm. The gate drive circuits 103U and 103L include an overcurrent detection unit that monitors the current flowing through each switching element. When an overcurrent is detected, an overcurrent detection signal is sent to the motor control circuit 110.

[0030] A current detector 20 is installed on the output line from the inverter circuit 300 to the motor 900, and the current value of each phase is input to the motor control circuit 110. An example of two current detectors 20 is illustrated, but three can also be used. With two current detectors 20, the motor control circuit 110 calculates the current value of the remaining phases. The motor control circuit 110 controls the torque of the motor 900 through current feedback control.

[0031] The motor control circuit 110 includes an auxiliary power supply circuit 111 and a safety control circuit 112. For example, 12V power is supplied to the auxiliary power supply circuit 111 from a DC power source (low-voltage battery) 10, and power is supplied to the safety control circuit 112 via a diode. The safety control circuit 112 outputs a discharge command Ha (described later), causing the inverter circuit 300 to switch to a safe state.

[0032] On the busbars of the two poles of the DC power supply 901, in addition to the voltage smoothing capacitor 500 which smooths the applied voltage that changes during power conversion, the upper arm gate drive power supply circuit 200U, the lower arm gate drive power supply circuit 200L, the active discharge circuit 120 and the high voltage sensor circuit 130 are connected in parallel.

[0033] The upper arm gate drive power supply circuit 200U and the lower arm gate drive power supply circuit 200L receive a high-voltage power supply from the DC power supply 901, which powers the gate drive circuits 103U and 103L. Details will be described later. The upper arm gate drive power supply circuit 200U and the lower arm gate drive power supply circuit 200L also supply power to the active discharge circuit 120 and the motor control circuit 110.

[0034] When the circuit within the power conversion device 100 stops, the active discharge circuit 120 discharges the voltage applied to the two poles of the bus via the discharge resistor 121, reducing the voltage to a safe value. The high-voltage sensor circuit 130 detects the voltage applied to the two poles of the bus and outputs the detected voltage information Hv to the safety control circuit 112. Based on the voltage information Hv from the high-voltage sensor circuit 130, the safety control circuit 112 outputs a discharge command Ha to the active discharge circuit 120.

[0035] The motor control circuit 110 has: a first control mode that controls the switching elements of the inverter circuit 300 to turn on / off, performing power conversion between DC and AC power; and a second control mode that turns on all switching elements of either the upper or lower arm, causing a short circuit between the windings of the motor 900. In the second control mode, the inverter circuit 300 is in a three-phase short-circuit state.

[0036] When the motor 900 is rotating due to external force, if the input of DC power to the DC power supply 901 is cut off, the voltage smoothing capacitor 500 set between the positive and negative terminals of the inverter circuit 300 is charged by the induced power of the motor 900, and its voltage rises.

[0037] The high-voltage sensor circuit 130 charges the voltage smoothing capacitor 500 using the induced power from the motor 900, detects the voltage applied across the two poles of the bus, and inputs the detected voltage information Hv to the safety control circuit 112. When a high voltage (overvoltage) above a certain reference value is detected in the high-voltage sensor circuit 130, the safety control circuit 112 outputs a three-phase short-circuit signal and switches to the second control mode. Furthermore, it also switches to the second control mode when an abnormality is detected in the inverter operation. The gate drive circuits 103U and 103L output gate drive signals 104U and 104L, respectively, based on the gate drive commands 101U and 101L indicating a three-phase short circuit, which turn on all switching elements of the upper or lower arms of each phase of the inverter circuit 300. As a result, all switching elements of the upper or lower arms of each phase of the inverter circuit 300 are turned on, causing a three-phase short circuit. This protects the switching elements.

[0038] Furthermore, in this embodiment, the high-voltage sensor circuit 130 is driven based on power supplied from the upper arm gate drive power supply circuit 200U and the lower arm gate drive power supply circuit 200L. Therefore, voltage detection is possible even if either the upper arm gate drive power supply circuit 200U or the lower arm gate drive power supply circuit 200L fails. Moreover, for example, even if the voltage in the inverter rises due to the induced voltage caused by motor rotation during vehicle traction, three-phase short-circuit control can be performed without exceeding a specified voltage (e.g., 60V). Alternatively, in the event of a malfunction such as contactor 902 sticking, if active discharge continues, the discharge resistor may exceed its loss tolerance and burn out; however, discharge can be stopped based on the voltage slope when no discharge is detected.

[0039] The reference voltage of the high-voltage sensor circuit 130 can be generated on either the low-voltage circuit side or the high-voltage circuit side. When the reference voltage is generated on the high-voltage circuit side, the same power supply as the active discharge circuit can be used.

[0040] Figure 2 This is a circuit diagram of the gate drive power supply circuits 200U and 200L in this embodiment. Since the gate drive power supply circuit 200U for the upper arm and the gate drive power supply circuit 200L for the lower arm have the same circuit configuration, the gate drive power supply circuit 200U for the upper arm will be described in detail here.

[0041] The gate drive power supply circuit 200U employs an isolated flyback converter. The gate drive power supply circuit 200U includes a transformer 201U, a startup circuit 202U, and a power control IC 203U. The primary and secondary sides of the transformer 201U include a primary winding 204U, multiple secondary winding circuits 206U, a feedback winding circuit 207U, and a spare winding circuit 208U. In this embodiment, the gate drive power supply circuit 200U has three secondary winding circuits 206U, which serve as power supplies applied to the gate electrodes of the switching elements in the upper arm of the inverter circuit 300.

[0042] On the primary winding 204U of transformer 201U, FET205U is connected in series from high-voltage battery 901 via winding 204U. A signal is input to the gate of FET205U from terminal OUT of power control IC203U.

[0043] The startup circuit 202U is used to supply the power required to drive the power control IC 203U by taking the high-voltage DC power supply 901 as input. When the gate drive power supply circuit 200U is electrically connected to the high-voltage battery 901, the startup circuit 202U temporarily supplies power to the power control IC 203U using the power from the high-voltage battery 901, thereby causing the power control IC 203U to rise and start the gate drive power supply circuit 200U. After the gate drive power supply circuit 200U starts, it supplies power to the power control IC 203U through the feedback winding circuit 207U. The output potential of the feedback winding circuit 207U, which supplies power to the power terminal VCC of the power control IC 203U, is VCC_FB_H.

[0044] Power control IC 203U turns on FET 205U, allowing current to flow through the primary winding 204U of transformer 201U. By allowing current to flow through the primary winding, magnetic energy is stored in transformer 201U. When power control IC 203U turns off FET 205U, induced voltages are generated in multiple windings on the secondary side of transformer 201U. Through repeated switching of FET 205U by power control IC 203U, induced voltages are intermittently generated in the secondary windings. These induced voltages are smoothed by diodes and capacitors in the secondary winding circuit 206U, supplying the gate drive voltage. The gate drive voltages (VCC_UH, VCC_VH, VCC_WH) are the power supplies applied to the gate electrodes of the switching elements constituting the upper arm of inverter circuit 300.

[0045] The feedback winding circuit 207U connects a capacitor in parallel to the series circuit of the winding and the diode, and outputs power from one end of the feedback winding via the diode. The other end of the feedback winding is at the same potential HVDC_N as the negative bus. Furthermore, a series circuit of a resistor is connected in parallel with the capacitor. The voltage divided in this series circuit is input to the feedback terminal FB of the power control IC 203U. The power control IC 203U controls the switching of the FET 205U in a manner that keeps the input voltage to the feedback terminal FB constant, thereby stabilizing and maintaining a constant output voltage of the feedback winding and the gate drive voltage.

[0046] A backup winding circuit 208U is configured to supply power to the safety control circuit 112 of the motor control circuit 110. The backup winding circuit 208U consists of a capacitor and a resistor connected in parallel within a series circuit of the winding and diode, and outputs power from the backup winding via the diode. The output potential of the backup winding circuit 208U is VCC_Backup_H.

[0047] The gate drive power supply circuit 200U supplies the gate drive voltages (VCC_UH, VCC_VH, VCC_WH) for the upper arm of the inverter circuit 300, while the gate drive power supply circuit 200L supplies the gate drive voltages (VCC_UL, VCC_VL, VCC_WL) for the lower arm of the inverter circuit 300. The output potential of the feedback winding circuit 207L is VCC_FB_L. The output potential of the backup winding circuit 208L is VCC_Backup_L.

[0048] The gate drive power supply circuit 200U for the upper arm and the gate drive power supply circuit 200L for the lower arm are configured as a single circuit. In particular, transformers 201U and 201L can use transformers of the same specifications. Even when there are multiple power supply circuits, by reducing the types of transformers, mass production efficiency can be improved and cost increases can be suppressed.

[0049] Figure 3 This is a configuration diagram of the active discharge circuit 120. As described above, the active discharge circuit 120 is used to discharge the charge stored in the voltage smoothing capacitor 500 in the device through the discharge resistor 121 when the power conversion device 100 stops, thereby reducing the voltage to a safe value.

[0050] The active discharge circuit 120 includes a discharge control circuit 123 and a semiconductor element 124 composed of a FET or similar device corresponding to a high voltage. A discharge command Ha is input to the active discharge circuit 120 from a safety control circuit 112. The discharge control circuit 123 drives the semiconductor element 124 according to the discharge command Ha. The active discharge circuit 120 includes an isolation interface for transmitting signals between the low-voltage circuit and the high-voltage circuit.

[0051] An active discharge power supply 122 is supplied to the active discharge circuit 120, which serves as the power source, thereby enabling the discharge control circuit 123 to operate. The active discharge power supply 122 is redundantly provided by connecting the FB output (VCC_FB_H) of transformer 201U and the FB output (VCC_FB_L) of transformer 201L via diodes.

[0052] Figure 4 This is a schematic diagram showing the configuration of the gate drive power supply circuits 200U and 200L in this embodiment. Figure 1 and Figure 2 As shown, the input power to the gate drive power supply circuits 200U and 200L is a high-voltage power supply from the DC power supply 901, for example, 400V. Additionally, the outputs from the gate drive power supply circuits 200U and 200L are the power supplies (VCC_UH, VCC_VH, VCC_WH, VCC_UL, VCC_VL, VCC_WL) for the three-arm gate drive circuits 103U and 103L, the backup power supplies (VCC_Backup_H, VCC_Backup_L) to the low-voltage circuit (motor control circuit 110), and the feedback outputs (VCC_FB_H, VCC_FB_L and their voltage dividers). The gate drive power supply circuits 200U and 200L each have a first transformer 201U for the upper arm and a second transformer 201L for the lower arm, but they can use transformers of the same specifications. The feedback output will be output as a voltage divider of the feedback voltage corresponding to the output voltages of the gate drive circuits 103U and 103L to the control ICs 203U and 203L, respectively, and as follows: Figure 1 and Figure 3 As shown, the upper and lower outputs are connected via diode OR to provide power to the active discharge circuit 120. The backup power output is as follows. Figure 1 As shown, the upper and lower outputs are connected by diodes OR and supplied to the low-voltage circuit (motor control circuit 110).

[0053] Figure 5 This is a schematic diagram illustrating the configuration of a centralized gate drive power supply circuit with a high-voltage power supply as the input, serving as a first comparative example. The outputs are the power supply for the 6-arm gate drive circuit, the backup power supply to the low-voltage circuit, and the feedback output. Figure 4 The gate drive power supply circuit includes two transformers, and Figure 5 The gate drive power supply circuit includes a single transformer 201. Since a single transformer supplies power to all six arms, in addition to requiring a larger size... Figure 4In addition to the larger transformer, the size of the FET205 used for current control is also increased, and the cost of each gate drive power supply circuit is also increased. Furthermore, in the event of a low-voltage power loss, the safety control circuit 112 can be activated by power from the backup power supply, but if the gate drive power supply circuit also fails when the low-voltage power loss occurs, the safety control action cannot be performed.

[0054] Figure 6 This is a second comparative example, showing a schematic diagram of a centralized gate drive power supply circuit with a low-voltage power supply as input. The output is the power supply and feedback output for the 6-arm gate drive circuit. (Compared to...) Figure 5 The gate drive power supply circuit also features a single transformer 201. When using a low-voltage power supply as input, a backup power supply is required to generate a low-voltage power supply from a high-voltage power supply in case of low-voltage power loss.

[0055] Figure 7 This is a third comparative example, illustrating the configuration of a distributed gate drive power supply circuit with a low-voltage power supply as input. (Compared to...) Figure 6 Unlike the gate drive power supply circuit, each arm has one transformer for its power output. That is, the 6 arms have 6 transformers. This is also consistent with... Figure 6 Similarly, in gate power supply circuits, a backup power supply is needed to generate low-voltage power from high-voltage power in case of low-voltage power loss. Furthermore, in distributed gate drive power supply circuits, low-voltage power is generally used as the input, not high-voltage power. This is because it's necessary to increase the size to handle high voltage, or it's difficult to increase the inductance of the primary winding used to handle high-voltage input, or wiring six high-voltage inputs on the substrate is area-disadvantageous.

[0056] Compared to Figures 5-7 The comparative example shown, Figure 4 The embodiment shown has the following advantages. The motor control circuit 110 operates powered by the low-voltage power supply LVDC_P (low-voltage battery 10). In the event of a low-voltage power supply failure, this embodiment provides a backup power supply, thus enabling the motor control circuit 110 (safety control circuit 112) to operate with power from the backup power supply. Furthermore, in this embodiment, since backup power supplies are provided on the gate drive power circuit 200U side and the gate drive power circuit 200L side, even if one gate drive power circuit fails in the event of a low-voltage power supply failure, safety control operations can be performed using power from the backup power supplies of the remaining gate drive power circuits.

[0057] The safety control circuit 112 can be powered by the low-voltage battery 10 or by the backup winding circuit 208U or 208L. Therefore, even if the backup power supply of one side fails when the low-voltage power supply is lost, the safety control circuit 112 powered by the backup power supply of the other side can still output a three-phase short-circuit signal.

[0058] Furthermore, even if the backup power supply of one side fails when the low-voltage power supply is lost, the safety control circuit 112, powered by the backup power supply of the other side, can still output a discharge command Ha to the active discharge circuit 120. The active discharge circuit 120 receives power from the backup power supplies on the gate drive power supply circuit 200U side and the gate drive power supply circuit 200L side. Therefore, even if one of the gate drive power supply circuits fails, the active discharge circuit 120 can still operate by being powered by the other backup power supply.

[0059] Additionally, using Figure 8 and Figure 9 This represents the diagnostic flowchart from the HV power-on to the start of gate drive operation. Figure 8 This is a flowchart of the existing diagnostic methods. Figure 9 This is a diagnostic flowchart for this implementation method.

[0060] By connecting the low-voltage power supply (low-voltage battery 10), the ignition is activated, the motor control circuit operates, and the CPU within the circuit begins to function. Before the power conversion device begins operation, a diagnostic program checks for any abnormalities within the power conversion device. This diagnostic program also includes checking for abnormalities in the gate drive circuit. The gate drive circuit diagnosis must be performed after the gate drive power supply circuit has stabilized. This is because, before the power supply stabilizes, it is naturally in an abnormal state.

[0061] In addition, the motor control circuit includes a fault management circuit that manages anomalies in the gate drive circuit. When a signal (fault signal) indicating an abnormal state of the gate drive circuit is input to the fault management circuit, it retains the anomaly information and notifies the CPU. Upon detecting the anomaly notification from the fault management circuit, the CPU performs an anomaly handling procedure. Furthermore, if the CPU determines that normal operation can be restored, it resets the fault management circuit, clearing the anomaly information. Abnormal states of the gate drive circuit include UVLO (undervoltage malfunction prevention), OVLO (overvoltage malfunction prevention), overcurrent detection, and overtemperature detection.

[0062] Since the gate drive power supply circuit is generated by a high-voltage power supply, the voltage of the high-voltage power supply becomes the trigger for diagnosis. Previously, after confirming that the monitored value of the high-voltage power supply voltage remained above 30V for more than 40ms, it was expected that the UVLO of the gate drive circuit would be deactivated to reset the fault management circuit. If the gate drive circuit started normally, the fault management circuit's abnormality information would be cleared, and the inverter could begin operation. Furthermore, values ​​such as 30V or 40ms are examples. The waiting time is set to account for the maximum time considering high-voltage power supply voltage, temperature, and component deviations.

[0063] In this embodiment, since the backup power supply output voltage and the gate drive power supply voltage are generated by a single transformer, their voltages are correlated. Therefore, if the backup power supply output voltage is monitored in the motor control circuit 110, the rise of the gate drive power supply voltage can be estimated based on this backup power supply output voltage, thus eliminating the need to set a waiting time. In other words, the gate drive operation can be quickly initiated based on operating conditions such as the rise rate of the high voltage or temperature.

[0064] Symbol Explanation

[0065] 10: Low-voltage battery

[0066] 20: Current detector

[0067] 100: Power conversion device

[0068] 101: Gate drive instruction

[0069] 103: Gate drive circuit

[0070] 104: Gate drive signal

[0071] 110: Motor control circuit

[0072] 111: Auxiliary power supply circuit

[0073] 112: Safety control circuit

[0074] 120: Active discharge circuit

[0075] 121: Discharge resistor

[0076] 122: Active discharge power supply

[0077] 123: Discharge control circuit

[0078] 124: Semiconductor Components

[0079] 130: High-voltage sensor circuit

[0080] 200: Gate drive power supply circuit

[0081] 201: Transformer

[0082] 202: Start-up circuit

[0083] 203: Power Control IC

[0084] 204: Primary winding

[0085] 205: FET

[0086] 206: Secondary winding circuit

[0087] 207: Feedback winding circuit

[0088] 208: Spare winding circuit

[0089] 300: Inverter circuit

[0090] 500: Capacitor for voltage smoothing

[0091] 900: Motor

[0092] 901: High-voltage battery

[0093] 902: Contactor.

Claims

1. A power conversion device that converts DC power supplied from a DC power source into AC power, characterized in that it comprises: Multiple switching elements constitute the upper and lower arms of each phase in a three-phase inverter circuit; Multiple driving circuits, each driving the multiple switching elements; A power supply circuit that supplies power to the plurality of drive circuits; and A discharge circuit is used to discharge the capacitors connected in parallel with the three-phase inverter circuit. The power supply circuit has a first transformer and a second transformer whose primary windings are connected in parallel with the DC power supply. The secondary winding of the first transformer supplies power to the drive circuit that drives the plurality of switching elements constituting the upper arm, and also supplies power to the low-voltage circuit connected to the low-voltage power supply. The secondary winding of the second transformer supplies power to the drive circuit that drives the plurality of switching elements constituting the lower arm, and also supplies power to the low-voltage circuit. The first transformer and the second transformer each have a feedback winding, which outputs a feedback voltage corresponding to the voltage output to the drive circuit to the power control IC. The discharge circuit is driven by power supplied from the feedback windings of the first transformer and the second transformer.

2. The power conversion device according to claim 1, characterized in that, It includes a voltage sensor circuit, which is connected in parallel with the three-phase inverter circuit and detects the voltage applied to the capacitor. The secondary windings of the first transformer and the second transformer supply power to the low-voltage circuit and to the voltage sensor circuit.

3. The power conversion device according to claim 1 or 2, characterized in that, The first transformer and the second transformer are transformers of the same specifications.

4. The power conversion device according to claim 1 or 2, characterized in that, The low-voltage circuit determines the startup status of the drive circuit based on the voltage supplied from the first transformer and the second transformer.

5. The power conversion device according to claim 3, characterized in that, The low-voltage circuit determines the startup status of the drive circuit based on the voltage supplied from the first transformer and the second transformer.

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