Power converter

Abstract

An electric power conversion device (1000) comprising switching elements (411,421) connected in series as the upper arms and the lower arms, a gate drive circuit (900) which drives the switching elements, a controller (910) which is operated by a predetermined low voltage supplied from a low-voltage power supply (4000) and which outputs drive signals for driving the switching elements to the gate drive circuit, a gate power supply circuit (800) which generates gate drive voltages for operating the gate drive circuit and which supplies the generated gate drive voltages to the gate drive circuit, and a backup power supply circuit (700) which generates a backup voltage to be used in place of the low voltage by controlling a current supplied from a high-voltage power supply (2000) to the primary winding of an isolation transformer and which supplies the generated backup voltage to the controller, wherein the backup power supply circuit is activated by an activation voltage output from the gate power supply circuit.

Description

Technical Field

[0001] The present invention relates to a power conversion device.

Background Art

[0002] A power conversion device that converts DC power into AC power includes a plurality of phases of upper and lower arm series circuits each configured by connecting a switching element of an upper arm and a switching element of a lower arm in series. The switching element is driven by a drive signal output from a controller via a gate drive circuit. The controller is normally supplied with power from a low-voltage power supply, but has a backup power supply circuit to compensate for its operation even when the low-voltage power supply is lost. The power of the backup power supply circuit is supplied from a high-voltage power supply different from the low-voltage power supply, and in this case, a startup circuit for stepping down the voltage of the high-voltage power supply to start the backup power supply circuit is required.

[0003] Patent Document 1 discloses an inverter control circuit that turns on a specific switching element even when there is an abnormality in the low-voltage power supply without adding a dedicated microcomputer. Patent Document 2 discloses a device that smoothly controls an inverter even when the power supply of the control circuit of the inverter is lost while suppressing an increase in the device scale.

Prior Art Documents

Patent Documents

[0006] The power conversion device according to the present invention comprises a switching element connected in series with upper and lower arms, a gate drive circuit for driving the switching element, a controller that operates on a predetermined low voltage supplied from a low-voltage power supply and outputs a drive signal to the gate drive circuit for driving the switching element, a gate power supply circuit that generates a gate drive voltage for operating the gate drive circuit and supplies the generated gate drive voltage to the gate drive circuit, and a backup power supply circuit that controls the current supplied from a high-voltage power supply to the primary winding of an isolation transformer to generate a backup voltage to replace the low voltage and supplies the generated backup voltage to the controller, wherein the backup power supply circuit is started by a start voltage output from the gate power supply circuit. [Effects of the Invention]

[0007] According to the present invention, the startup circuit for activating the backup power supply circuit can be omitted. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is an overall configuration diagram of the power conversion device in the first embodiment. [Figure 2] Figure 2 is a detailed diagram of the main components of the power converter in the first embodiment. [Figure 3] Figures 3(A) to 3(F) are timing charts showing the operation of the backup power supply circuit in the first embodiment. [Figure 4] Figure 4 shows the wiring pattern of the power converter in the first embodiment. [Figure 5] Figure 5 shows the wiring pattern of the power converter in the comparative example. [Figure 6] Figure 6 is an overall configuration diagram of the power conversion device in the second embodiment. [Figure 7]Figure 7 is a detailed diagram of the main components of the power converter in the second embodiment. [Figure 8] Figures 8(A) to 8(G) are timing charts showing the operation of the backup power supply circuit and the gate power supply circuit in the second embodiment.

[0009] Embodiments of the present invention will be described below with reference to the drawings. The following description and drawings are illustrative for illustrating the present invention, and have been omitted and simplified as appropriate for clarity of explanation. The present invention can also be carried out in various other forms. Unless otherwise specified, each component may be singular or plural.

[0010] [First Embodiment] Figure 1 is an overall configuration diagram of the power converter 1000 in the first embodiment. The power converter 1000 converts DC power supplied from a high-voltage DC power source 2000, such as a battery, into AC power to drive the motor 3000. The high-voltage power source 2000 supplies DC power between the positive busbar P and the negative busbar N of the power converter 1000 via a contactor 2001. The motor 3000 is, for example, a three-phase induction motor and is used as a power source for a vehicle. The motor 3000 is equipped with an angle sensor 3001, such as a resolver, which outputs the rotation angle.

[0011] The power converter 1000 includes a capacitor module 100 connected in parallel between the positive busbar P and the negative busbar N to smooth the DC current, a voltage detector 200 for detecting the DC voltage between the positive busbar P and the negative busbar N, and an inverter circuit 400 for performing power conversion. It also includes a DC current detector 300 for detecting the series current flowing through the positive busbar P. Furthermore, the power converter 1000 includes an output current detector 500, a backup power supply circuit 700, a gate power supply circuit 800, a gate drive circuit 900, and a controller 910.

[0012] The backup power supply circuit 700, gate power supply circuit 800, gate drive circuit 900, and controller 910 are arranged on the circuit board 600. The circuit board 600 is divided into a high-voltage side 600H and a low-voltage side 600L, and the backup power supply circuit 700 and gate power supply circuit 800 are separated into the high-voltage side 600H and the low-voltage side 600L by insulating elements 600a such as transformers. The gate drive circuit 900 is located on the high-voltage side 600H of the circuit board 600, and the controller 910 is located on the low-voltage side 600L of the circuit board 600.

[0013] The inverter circuit 400 includes a power module 410 that constitutes an upper and lower arm series circuit, consisting of a switching element 411 and a diode 412 that operates as an upper arm, and a switching element 421 and a diode 422 that operates as a lower arm. Three power modules 410 are provided to correspond to the phase windings of the motor 3000, for each phase (U phase, V phase, W phase). In other words, the inverter circuit 400 has three arms, each consisting of an upper arm switching element 411 and a lower arm switching element 421 connected in series between the DC positive busbar P and the negative busbar N. Here, we will explain using a three-phase example, but for example, a configuration with multiple power modules 410 to match the number of phases of the motor 3000 is also possible.

[0014] The switching element 411 on the upper arm and the switching element 421 on the lower arm are provided with emitter sense terminals, which are connected to the gate drive circuit 900 to detect the current flowing through the switching elements 411 and 421. The emitter of the lower arm switching element 421 is connected to ground GND3 in the gate drive circuit 900. Similarly, the emitters of the lower arm switching elements 421 of the other phases are connected to ground GND2 and GND1 in the gate drive circuit 900.

[0015] The base terminals of the switching elements 411 and 421 receive a drive signal Pw, which is a PWM signal output from the controller 910, via the gate drive circuit 900. The switching elements 411 and 421 are, for example, IGBT (Insulated Gate Bipolar Transistor), MOSFET (Metal Oxide Semiconductor Field Effect Transistor), SJ-MOSFET (Super Junction Metal Oxide Semiconductor Field Effect Transistor), or power semiconductor elements made of materials such as SiC (silicon carbide) and GaN (gallium nitride). is a power semiconductor device.

[0016] The output current detector 500 detects the AC current output from the connection point between the switching element of the upper arm and the switching element of the lower arm for each phase, and outputs each detected value to the controller 910.

[0017] Outside the power conversion device 1000, a DC low-voltage power supply 4000 such as a battery is provided. The contactor 4001 is turned on according to the ignition key of the vehicle, and a low voltage is supplied from the low-voltage power supply 4000 via the diode D1 to the controller 910. Then, according to the torque command from the upper controller (not shown), the detected voltage from the voltage detector 200, the DC current detection value from the DC current detector 300, the output current detection value from the output current detector 500, and the rotation angle from the angle sensor 3001, a drive signal Pw is output to the gate drive circuit 900.

[0018] The backup power supply circuit 700 controls the current supplied to the primary winding of the isolation transformer based on the power supplied from the high-voltage power supply 2000 via the positive bus bar P, generates a backup voltage that replaces the low voltage supplied from the low-voltage power supply 4000, and supplies it to the controller 910 and the gate power supply circuit 800 via the diode D2. This backup power supply circuit 700 is activated when the startup voltage (details will be described later) output from the gate power supply circuit 800 is supplied via the reverse-current prevention diode D0 and the current-limiting resistor R0. The reverse-current prevention diode D0 and the current-limiting resistor R0 prevent the gate power supply circuit 800 from being overloaded and overvoltage when the voltage of the backup power supply circuit 700 is abnormal. Details of the backup power supply circuit 700 will be described later.

[0019] The gate power supply circuit 800 generates a gate drive voltage for operating the gate drive circuit 900 based on the low voltage from the low-voltage power supply 4000 or the backup voltage from the backup power supply circuit 700, and supplies the generated gate drive voltage to the gate drive circuit 900. The gate power supply circuit 800 and the controller 910 are normally supplied with a voltage lower than that of the low-voltage power supply 4000. When the voltage lower than that of the low-voltage power supply 4000 is no longer supplied due to some malfunction, a backup voltage that replaces the low voltage is supplied from the backup power supply circuit 700.

[0020] The gate drive circuit 900 operates using the gate drive voltage supplied from the gate power supply circuit 800, and drives the switching elements 411 and 421 based on the drive signal Pw output from the controller 910. The grounds GND1, GND2, and GND3 in the gate drive circuit 900 are connected to the ground GND0 in the backup power supply circuit 700. Details of the gate drive circuit 900 will be described later.

[0021] Figure 2 is a detailed configuration diagram of the main part of the power conversion device 1000 in the first embodiment. In Figure 2, a power module 410 for one phase is shown, while the other phases are omitted from the illustration. In addition, the gate power supply circuit 800 and gate drive circuit 900 corresponding to the switching element 421 of the lower arm are shown, while the gate power supply circuit 800 and gate drive circuit 900 corresponding to the switching element 411 of the upper arm are omitted from the illustration.

[0022] The backup power supply circuit 700 includes a first power supply IC 710 and an isolation transformer TB1. Power is supplied to one end of the primary winding Nb1 of the isolation transformer TB1 from the high-voltage power supply 2000 via a positive busbar P. The other end of the primary winding Nb1 of the isolation transformer TB1 is connected to ground GND0 via a field-effect transistor FE1 through a resistor R1.

[0023] The first power supply IC 710 starts up when the startup voltage Va generated by the gate power supply circuit 800 is supplied to its power supply terminal Vcc via the reverse current prevention diode D0 and current limiting resistor R0. Then, the field-effect transistor FE1 is switched and controlled by the signal output from the signal terminal SW, and a backup voltage Vb is generated by flyback, which operates with the secondary winding Nb2 of the isolation transformer TB1, a diode, and a capacitor. This backup voltage Vb is supplied to the controller 910 and the gate power supply circuit 800. This backup voltage Vb is also supplied to the gate power supply circuit 800 corresponding to the upper arm switching element 411, which is not shown in the figure.

[0024] Furthermore, the isolation transformer TB1 is provided with an auxiliary winding Nbc, and the output voltage from this auxiliary winding Nbc is used to generate a feedback voltage Vf. This feedback voltage Vf is supplied to the power terminal Vcc of the first power supply IC 710 via a diode, and is also divided and input to the feedback terminal FB of the first power supply IC 710. The first power supply IC 710 switches and controls the field-effect transistor FE1 so that the divided voltage of the feedback voltage Vf input to the feedback terminal FB becomes a predetermined set voltage. Here, since the voltage of the feedback voltage Vf is set to a voltage higher than the startup voltage Va, after the first power supply IC 710 is started, it continues to operate using the power from the feedback voltage Vf. As a result, after the first power supply IC 710 is started by the startup voltage Va generated by the gate power supply circuit 800, it continues to operate using the feedback voltage Vf.

[0025] The gate power supply circuit 800 includes a second power supply IC 810 and an isolation transformer TG1. The second power supply IC 810 is supplied with a low voltage from the low-voltage power supply 4000 or a backup voltage Vb from the backup power supply circuit 700 at its power terminal Vcc. One end of the primary winding Ng1 of the isolation transformer TG1 is connected to the power terminal Vcc of the second power supply IC 810, and the other end is connected to the low-voltage ground GND4 via a resistor R2 through a field-effect transistor FE2.

[0026] The second power supply IC 810 controls the switching of the field-effect transistor FE2 by a signal output from its signal terminal SW, generating a gate drive voltage via flyback, which operates using the secondary winding Ng2 of the isolation transformer TG1, a diode, and a capacitor. The secondary winding Ng2 of the isolation transformer TG1 has three gate drive circuits GD1, GD2, and GD3 that drive the switching element 421 on the lower arm, each generating a gate drive voltage. Of these, the gate drive voltage supplied to one gate drive circuit GD3 is supplied to the backup power supply circuit 700 as a starting voltage Va via a reverse current prevention diode D0 and a current limiting resistor R0. This eliminates the need for a separate starting circuit to start the backup power supply circuit 700. In addition, the isolation transformer TG1 is provided with an auxiliary winding Ngc, and the feedback voltage generated using the output voltage from this auxiliary winding Ngc is input to the feedback terminal FB of the second power supply IC 810. The second power supply IC 810 controls the switching of the field-effect transistor FE2 so that the feedback voltage input to the feedback terminal FB becomes a predetermined set voltage.

[0027] The gate drive circuit 900 shows three gate drive circuits GD1, GD2, and GD3 that drive the switching element 421 of the lower arm. In gate drive circuit GD3, the emitter of the switching element 421 is connected to ground GND3, the base of the switching element 421 is connected to the terminal of the drive signal Pw, and the emitter sense is connected to terminal Es. The gate drive circuits GD1 and GD2 are connected similarly. The drive signal Pw output from the controller 910 is input to the base of the switching element 421, driving the switching element 421 by turning it on and off. The current flowing through the switching element 421 is transmitted from the emitter sense to the controller 910 via the gate drive circuit GD3, and the controller 910 performs control such as overcurrent control.

[0028] The gate drive circuits GD1, GD2, and GD3 drive the switching elements 421 on the lower arms of their respective phases. The grounds GND1, GND2, and GND3 of the gate drive circuits GD1, GD2, and GD3, i.e., the emitters of the switching elements 421 on the lower arms of their respective phases, are connected to ground GND0 in the backup power supply circuit 700. The reason for this will be explained later.

[0029] Figures 3(A) to 3(F) are timing charts showing the operation of the backup power supply circuit 700 in the first embodiment. Figure 3(A) shows the low voltage supplied from the low voltage power supply 4000, Figure 3(B) shows the startup voltage Va supplied from the gate drive circuit GD3, Figure 3(C) shows the signal output from the signal terminal SW of the first power supply IC 710, Figure 3(D) shows the high voltage supplied from the high voltage power supply 2000, Figure 3(E) shows the feedback voltage Vf generated by the backup power supply circuit 700, and Figure 3(F) shows the backup voltage Vb generated by the backup power supply circuit 700.

[0030] The following explanation will refer to the detailed configuration diagram of the main components of the power converter 1000 shown in Figure 2. When the contactor 4001 is turned on, a low voltage is supplied from the low-voltage power supply 4000, and as shown in Figure 3(A), the voltage input to the controller 910 and the gate power supply circuit 800 gradually increases from 0V to 12V. 12V is an example of a low voltage. When this voltage reaches the starting voltage vi of the second power supply IC 810 of the gate power supply circuit 800, the gate power supply circuit 800 starts up, as shown in Figure 3(B).

[0031] When the gate power supply circuit 800 starts up, and the startup voltage Va becomes greater than the operating voltage vj of the first power supply IC 710 of the backup power supply circuit 700, as shown in Figure 3(B), the first power supply IC 710 starts switching control operation, as shown in Figure 3(C). The startup voltage Va of 15V is just one example.

[0032] The high-voltage power supply 2000, with the contactor 2001 turned on, gradually increases to, for example, 400V, as shown in Figure 3(D), supplying power to the backup power supply circuit 700. As a result, a high voltage is applied to the primary winding Nb1 of the isolation transformer TB1, as shown in Figure 3(E), generating a feedback voltage Vf. The feedback voltage Vf is controlled to a voltage higher than the startup voltage Va, for example, 16V, by the switching control of the field-effect transistor FE1 performed by the first power supply IC 710. Furthermore, the backup power supply circuit 700 generates a backup voltage Vb, as shown in Figure 3(F). The backup voltage Vb is, for example, 8V. The contactor 4001 is turned on, and the backup power supply circuit 700 becomes operational after time Tb. Since power is supplied to the backup power supply circuit 700 from the high-voltage power supply 2000, even if the low voltage supply from the low-voltage power supply 4000 is lost due to some malfunction, the backup voltage Vb is supplied from the backup power supply circuit 700.

[0033] Figure 4 shows the wiring pattern of the power converter 1000 in the first embodiment. The circuit board 600 is divided into a high-voltage side 600H and a low-voltage side 600L. The backup power supply circuit 700 and the gate power supply circuit 800 are separated into the high-voltage side 600H and the low-voltage side 600L by insulating elements 600a such as the isolation transformer TB1. The gate drive circuit 900 is located on the high-voltage side 600H of the circuit board 600, and the controller 910 is located in the circuit area 600R of the low-voltage side 600L of the circuit board 600. The inverter circuit 400 is connected between the positive busbar P and the negative busbar N, and the switching elements 411 and 421 within the inverter circuit 400 are connected to the wiring patterns on the circuit board 600, but the details of these connections are omitted.

[0034] The gate drive circuit 900 supplies the startup voltage Va to the backup power supply circuit 700. In addition, the grounds GND1, GND2, and GND3 of the gate drive circuit 900, i.e., the emitter 412E of the switching element 421, are connected to ground GND0 in the backup power supply circuit 700 via the gate drive circuit 900.

[0035] The low-voltage power supply 4000 supplies low voltage to the electronic components in the low-voltage side 600L circuit region 600R, such as the controller 910. The high-voltage power supply 2000 supplies high voltage to the electronic components in the high-voltage side 600H of the power converter 1000 via the positive busbar P and the negative busbar N. The negative busbar N is connected to grounds GND1, GND2, and GND3, which are referenced to the emitter 412E of the switching element 421.

[0036] In other words, in this embodiment, the ground GND0 of the backup power supply circuit 700 is connected to the emitter-referenced grounds GND1, GND2, and GND3 of the gate drive circuit 900, and the emitter-referenced grounds GND1, GND2, and GND3 are connected to the negative terminal of the high-voltage power supply 2000 via the negative terminal busbar N. This makes the operation of the gate drive circuit 900 and the backup power supply circuit 700 more stable compared to the case where the ground GND0 of the backup power supply circuit 700 is directly connected to the negative terminal busbar N.

[0037] Figure 5 shows the wiring pattern of the power converter 1000 in a comparative example. The comparative example shown in Figure 5 is an example to which the first embodiment is not applied, and is an example for comparison with the first embodiment. The same reference numerals are used for parts that are the same as in Figure 4, and their explanations are simplified.

[0038] As shown in Figure 5, in the comparative example, the ground GND0 of the backup power supply circuit 700 is connected to the negative busbar N. In this case, a loop current is generated between the emitter of the gate drive circuit 900 and the negative busbar N, which is the ground GND0 of the backup power supply circuit 700, creating a potential difference between the gate drive circuit 900 and the backup power supply circuit 700. As a result, the operation of the gate drive circuit 900 becomes unstable. On the other hand, according to the embodiment shown in Figure 4, the operation of both the gate drive circuit 900 and the backup power supply circuit 700 can be made stable.

[0039] According to the first embodiment of the present invention, the gate power supply circuit 800, which supplies power to the gate drive circuit 900, activates the backup power supply circuit 700. This eliminates the need for a separate activation circuit to activate the backup power supply circuit, thereby reducing component costs and the mounting area on the circuit board.

[0040] [Second Embodiment] Figure 6 is an overall configuration diagram of the power converter 1000 in the second embodiment. In the first embodiment, an example was shown in which a backup voltage is supplied from the backup power supply circuit to the gate power supply circuit and the controller. In the second embodiment, however, a backup voltage is supplied from the backup power supply circuit to the controller, and a high voltage is supplied to the gate power supply circuit. The same reference numerals are used for parts that are the same as in Figure 1 of the first embodiment, and their explanations are simplified.

[0041] The backup power supply circuit 700, gate power supply circuit 800, gate drive circuit 900, controller 910, and voltage conversion circuit 920 are arranged on the circuit board 600. The circuit board 600 is divided into a high-voltage side 600H and a low-voltage side 600L by an insulating element 600a, and the backup power supply circuit 700 is separated into a high-voltage side 600H and a low-voltage side 600L by an insulating element 600a such as a transformer. The gate power supply circuit 800, gate drive circuit 900, and voltage conversion circuit 920 are located on the high-voltage side 600H, and the controller 910 is located on the low-voltage side 600L of the circuit board 600.

[0042] The backup power supply circuit 700 generates a backup voltage to replace the low voltage supplied by the low-voltage power supply 4000 by controlling the current supplied to the primary winding of the isolation transformer based on the power supplied from the high-voltage power supply 2000 via the positive busbar P and negative busbar N, and supplies it to the controller 910 via diode D2. This backup power supply circuit 700 is started by the start voltage output from the gate power supply circuit 800, which is supplied via the reverse current prevention diode D0 and the current limiting resistor R0. The reverse current prevention diode D0 and the current limiting resistor R0 prevent the gate power supply circuit 800 from becoming overloaded and overvoltage if the voltage of the backup power supply circuit 700 is abnormal.

[0043] The controller 910 is normally supplied with a lower voltage than the low-voltage power supply 4000. However, if the low-voltage power supply 4000 fails to supply a lower voltage for any reason, the backup power supply circuit 700 will supply a backup voltage to replace the lower voltage. Details of the backup power supply circuit 700 will be described later.

[0044] The gate power supply circuit 800 generates a gate drive voltage to operate the gate drive circuit 900 based on the power supplied from the high-voltage power supply 2000 via the positive busbar P and the negative busbar N, and supplies the generated gate drive voltage to the gate drive circuit 900. The gate drive circuit 900 drives the switching elements 411 and 421 based on the drive signal Pw output from the controller 910.

[0045] In the first embodiment, the emitters of the switching elements 421 of each phase of the lower arm were connected to the ground in the gate drive circuit 900, but in this embodiment, they are not connected. Furthermore, the ground in the gate drive circuit 900 is not connected to the ground in the backup power supply circuit 700.

[0046] The voltage conversion circuit 920 steps down the high voltage supplied from the high-voltage power supply 2000 via the positive busbar P and the negative busbar N to a predetermined operating voltage for operating the gate power supply circuit 800. After the operating voltage supplied from the voltage conversion circuit 920 exceeds a predetermined value, the gate power supply circuit 800 outputs a start voltage to the backup power supply circuit 700 via the reverse current prevention diode D0 and the current limiting resistor R0, thereby starting up the backup power supply circuit 700.

[0047] Figure 7 is a detailed diagram of the main components of the power converter 1000 in the second embodiment. In Figure 7, the gate power supply circuit 800 and gate drive circuit 900 corresponding to the switching element 421 of the lower arm are shown, while the gate power supply circuit 800 and gate drive circuit 900 corresponding to the switching element 411 of the upper arm are omitted from the illustration. The same reference numerals are used for parts that are the same as in Figure 2 of the first embodiment, and their descriptions are simplified.

[0048] The backup power supply circuit 700 includes a first power supply IC 710 and an isolation transformer TB1. Power is supplied to one end of the primary winding Nb1 of the isolation transformer TB1 from the high-voltage power supply 2000 via a positive busbar P. The other end of the primary winding Nb1 of the isolation transformer TB1 is connected to the ground GND0 of the first power supply IC 710 via a field-effect transistor FE1 through a resistor R1. Ground GND0 is connected to the negative busbar N.

[0049] The first power supply IC 710 starts up when the start voltage Va generated by the gate power supply circuit 800 is supplied to its power supply terminal Vcc via the reverse current prevention diode D0 and current limiting resistor R0. Then, the field-effect transistor FE1 is switched on by a signal output from the signal terminal SW, and a backup voltage Vb is generated by flyback, which operates with the secondary winding Nb2 of the isolation transformer TB1, a diode, and a capacitor. This backup voltage Vb is supplied to the controller 910.

[0050] Furthermore, the isolation transformer TB1 is provided with an auxiliary winding Nbc, and the output voltage from this auxiliary winding Nbc is used to generate a feedback voltage Vf1. This feedback voltage Vf1 is supplied to the power terminal Vcc of the first power supply IC 710 via a diode, and is also divided into predetermined voltages and input to the feedback terminal FB of the first power supply IC 710. The first power supply IC 710 switches and controls the field-effect transistor FE1 so that the divided voltage of the feedback voltage Vf1 input to the feedback terminal FB becomes a predetermined set voltage. Here, as in the first embodiment, the voltage of the feedback voltage Vf1 is set to a voltage higher than the startup voltage Va, so after the first power supply IC 710 starts up, it continues to operate using the power from the feedback voltage Vf1.

[0051] The voltage conversion circuit 920 consists of a series circuit of a field-effect transistor FE3 and a Zener diode Z3 connected between the positive busbar P and the negative busbar N. The voltage from the positive busbar P is input to the gate of the field-effect transistor FE3 via resistor R3. The connection point between the field-effect transistor FE3 and the Zener diode Z3 is input to the power terminal Vcc of the second power supply IC 810 via diode D3. The voltage conversion circuit 920 converts the voltage from the high-voltage power supply 2000 into the operating voltage of the second power supply IC 810 of the gate power supply circuit 800. The output from the connection point between the field-effect transistor FE3 and the Zener diode Z3 of this voltage conversion circuit 920 is also supplied to the gate power supply circuit 800 corresponding to the switching element 411 on the upper arm, which is not shown in the diagram.

[0052] The gate power supply circuit 800 includes a second power supply IC 810 and an isolation transformer TG1. The second power supply IC 810 is activated when the operating voltage supplied to the power supply terminal Vcc from the voltage conversion circuit 920 exceeds a predetermined value. It switches and controls the field-effect transistor FE2 using a signal output from the signal terminal SW, generating a gate drive voltage by flyback operation using the secondary winding Ng2 of the isolation transformer TG1, a diode, and a capacitor. The secondary winding Ng2 of the isolation transformer TG1 has three gate drive circuits GD1, GD2, and GD3 that drive the switching element 421 on the lower arm, each generating a gate drive voltage.

[0053] Furthermore, the isolation transformer TG1 is provided with an auxiliary winding Ngc, and the feedback voltage Vf2 generated using the output voltage from this auxiliary winding Ngc is divided and input to the feedback terminal FB of the second power supply IC 810. The second power supply IC 810 of the gate power supply circuit 800 is started when the operating voltage supplied from the voltage conversion circuit 920 exceeds a predetermined value, and then switches and controls the field-effect transistor FE2 so that the divided voltage of the feedback voltage Vf2 input to the feedback terminal FB becomes a predetermined set voltage. In addition, the feedback voltage Vf2 is also input to the power terminal Vcc of the second power supply IC 810 via diode D4. That is, the power terminal Vcc of the second power supply IC 810 is supplied with either the feedback voltage Vf2 or the operating voltage from the voltage conversion circuit 920.

[0054] Here, since the feedback voltage Vf2 is set to a voltage higher than the operating voltage from the voltage conversion circuit 920, after the second power supply IC 810 is started, it continues to operate using the power from the feedback voltage Vf2. In addition, the feedback voltage Vf2 is input as the start voltage Va to the power terminal Vcc of the first power supply IC 710 in the backup power supply circuit 700 via the reverse current prevention diode D0 and the current limiting resistor R0, thereby starting the backup power supply circuit 700. That is, the gate power supply circuit 800 generates the start voltage Va and starts the backup power supply circuit 700 after the operating voltage supplied from the voltage conversion circuit 920 exceeds a predetermined value.

[0055] The gate drive circuit 900 shows three gate drive circuits GD1, GD2, and GD3 that drive the switching element 421 of the lower arm. The drive signal Pw output from the controller 910 is input to the base of the switching element 421, driving the switching element 421 by turning it on and off. The three gate drive circuits that drive the switching element 411 of the upper arm, which are not shown in the figure, have a similar configuration.

[0056] Figures 8(A) to 8(G) are timing charts showing the operation of the backup power supply circuit 700 and the gate power supply circuit 800 in the second embodiment. Figure 8(A) shows the high voltage supplied from the high-voltage power supply 2000, Figure 8(B) shows the operating voltage of the second power supply IC 810 supplied from the voltage conversion circuit 920, Figure 8(C) shows the signal output from the signal terminal SW of the second power supply IC 810, Figure 8(D) shows the feedback voltage Vf2 generated by the gate power supply circuit 800, Figure 8(E) shows the signal output from the signal terminal SW of the first power supply IC 710, Figure 8(F) shows the feedback voltage Vf1 generated by the backup power supply circuit 700, and Figure 8(G) shows the backup voltage Vb generated by the backup power supply circuit 700.

[0057] The following explanation will refer to the detailed configuration diagram of the main components of the power converter 1000 shown in Figure 7. When contactor 4001 is turned on, a low voltage is supplied from the low-voltage power supply 4000, enabling the controller 910 to operate. Also, when contactor 2001 is turned on, a high voltage is supplied from the high-voltage power supply 2000 to the voltage conversion circuit 920, as shown in Figure 8(A). As a result, the output voltage of the voltage conversion circuit 920 gradually increases from 0V to 12V. 12V is an example of a low voltage. When this voltage reaches the starting voltage vi of the second power supply IC 810 of the gate power supply circuit 800, the gate power supply circuit 800 starts up, as shown in Figure 8(C).

[0058] When the gate power supply circuit 800 starts up and the feedback voltage Vf2 becomes greater than the operating voltage vj of the first power supply IC 710 of the backup power supply circuit 700, as shown in Figure 8(D), the first power supply IC 710 starts switching control operation, as shown in Figure 8(E). The feedback voltage Vf2 of 16V is just one example.

[0059] When the first power supply IC 710 starts operating and controls the switching of the field-effect transistor FE1, a feedback voltage Vf1 is generated, as shown in Figure 8(F). At this time, the feedback voltage Vf1 is controlled to a voltage higher than the startup voltage Va, for example, 17V. Furthermore, the backup power supply circuit 700 generates a backup voltage Vb, as shown in Figure 8(G). The backup voltage Vb is, for example, 8V. The contactor 2001 is turned on, and the backup power supply circuit 700 becomes operational after time Tb. Since power is supplied to the backup power supply circuit 700 from the high-voltage power supply 2000, even if the low voltage supply from the low-voltage power supply 4000 is lost due to some malfunction, the backup voltage Vb is supplied from the backup power supply circuit 700.

[0060] According to a second embodiment of the present invention, the voltage conversion circuit 920 activates the gate power supply circuit 800, and the activated gate power supply circuit 800 activates the backup power supply circuit 700. This eliminates the need for a separate activation circuit to activate the backup power supply circuit, thereby reducing component costs and the mounting area on the circuit board.

[0061] In the first embodiment described above, if the low voltage supply from the low-voltage power supply 4000 is stopped from the beginning due to some malfunction, the gate power supply circuit 800 cannot be started, and therefore the backup power supply circuit 700 cannot be started. On the other hand, in the second embodiment, even if the low voltage supply from the low-voltage power supply 4000 is stopped from the beginning due to some malfunction, the operating voltage of the second power supply IC 810 can be generated by converting the high voltage supplied from the high-voltage power supply 2000 by the voltage conversion circuit 920, and the gate power supply circuit 800 can be started using this. Then, the backup power supply circuit 700 can be started using the start voltage Va (feedback voltage Vf2) output from the gate power supply circuit 800 after it has started. Therefore, according to the second embodiment, the availability of the power converter 1000 can be further improved.

[0062] According to the embodiments described above, the following effects and advantages can be obtained. (1) The power converter 1000 includes switching elements 411 and 42 connected in series to the upper and lower arms, a gate drive circuit 900 that drives the switching elements 411 and 42, a controller 910 that operates on a predetermined low voltage supplied from a low-voltage power supply 4000 and outputs a drive signal Pw to the gate drive circuit 900 to drive the switching elements 411 and 42, a gate power supply circuit 800 that generates a gate drive voltage to operate the gate drive circuit 900 and supplies the generated gate drive voltage to the gate drive circuit 900, and a backup power supply circuit 700 that controls the current supplied from the high-voltage power supply 2000 to the primary winding of the isolation transformer TB1 to generate a backup voltage Vb to replace the low voltage and supplies the generated backup voltage Vb to the controller 910. The backup power supply circuit 700 is started by a start voltage Va output from the gate power supply circuit 800. This eliminates the need for a start circuit to start the backup power supply circuit.

[0063] The present invention is not limited to the embodiments described above, and other forms conceivable within the scope of the technical concept of the present invention are also included within the scope of the present invention, as long as they do not impair the features of the present invention. Furthermore, configurations combining the embodiments described above are also possible. [Explanation of symbols]

[0064] 200...Voltage detector, 300...DC current detector, 400...Inverter circuit, 410...Power module, 411, 421...Switching elements, 412, 422...Diodes, 500...Output current detector, 600...Circuit board, 600a...Insulating element, 600H...High voltage side of circuit board, 600L...Low voltage side of circuit board, 700...Backup power supply circuit, 710...First power supply IC, 800...Gate power supply circuit, 810...Second power supply IC, 900, GD1, GD2, GD3...Gate drive circuit, 910...Controller, 1000...Electric Power converter, 2000... High voltage power supply, 2001... Contactor, 3000... Motor, 4000... Low voltage power supply, 4001... Contactor, TB1, TG1... Isolation transformer, FE1, FE2... Field-effect transistor, R1, R2... Resistor, Vcc... Power terminal, SW... Signal terminal, FB... Feedback terminal, Va... Startup voltage, Vb... Backup voltage, D0... Reverse current prevention diode, R0... Current limiting resistor, GND1, GND2, GND3... Ground, P... Positive busbar, N... Negative busbar, Pw... Drive signal.

Claims

1. A switching element connected in series to the upper and lower arms, A gate drive circuit for driving the switching element, A controller that operates using a predetermined low voltage supplied from a low-voltage power supply and outputs a drive signal to the gate drive circuit to drive the switching element, A gate power supply circuit that generates a gate drive voltage to operate the gate drive circuit and supplies the generated gate drive voltage to the gate drive circuit, The system includes a backup power supply circuit that controls the current supplied from the high-voltage power supply to the primary winding of the isolation transformer to generate a backup voltage to replace the low voltage, and supplies the generated backup voltage to the controller, The backup power supply circuit is a power converter that is activated by the activation voltage output from the gate power supply circuit.

2. In the power conversion device according to claim 1, The gate power supply circuit is a power conversion device that generates the gate drive voltage based on the low voltage and outputs the generated gate drive voltage as the startup voltage to the backup power supply circuit.

3. In the power conversion device according to claim 2, The backup power supply circuit is a power conversion device that supplies the backup voltage to the gate power supply circuit and the controller.

4. In the power conversion device according to claim 2, The gate power supply circuit is a power conversion device that generates the gate drive voltage and starts the backup power supply circuit after the low voltage supplied from the low voltage power supply exceeds a predetermined value.

5. In a power conversion device according to any one of claims 1 to 4, The ground of the backup power supply circuit is connected to the emitter-referenced ground of the gate drive circuit, and the emitter-referenced ground is connected to the negative terminal of the high-voltage power supply via a busbar in the power converter.

6. In the power conversion device according to claim 1, The gate power supply circuit is a power conversion device that generates the gate drive voltage and the startup voltage based on a predetermined high voltage supplied from the high-voltage power supply, and outputs the generated startup voltage to the backup power supply circuit.

7. In the power conversion device according to claim 6, The system includes a voltage conversion circuit that converts the high voltage supplied from the high-voltage power supply into the operating voltage of the gate power supply circuit, The gate power supply circuit is a power conversion device that operates using the operating voltage supplied from the voltage conversion circuit.

8. In the power conversion device according to claim 7, The gate power supply circuit is a power conversion device that generates the startup voltage and starts the backup power supply circuit after the operating voltage supplied from the voltage conversion circuit exceeds a predetermined value.

9. In the power conversion device according to claim 1, The backup power supply circuit includes a power supply IC that controls the current supplied from the high-voltage power supply to the primary winding of the isolation transformer, and the power supply IC is a power converter that is started up by receiving the start voltage output from the gate power supply circuit.

10. In the power conversion device according to claim 9, A power conversion device to which the startup voltage generated by the gate power supply circuit is supplied to the power supply terminal of the power supply IC via a reverse current prevention diode and a current limiting resistor.

11. In the power conversion device according to claim 10, The backup power supply circuit generates a feedback voltage based on the current supplied from the high-voltage power supply to the primary winding of the isolation transformer. A power converter to which, after the power supply IC is started up by receiving the aforementioned startup voltage, the feedback voltage generated by the backup power supply circuit is supplied to the power supply terminals.

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