WO2020031553A1

WO2020031553A1 - Control circuit

Info

Publication number: WO2020031553A1
Application number: PCT/JP2019/026206
Authority: WO
Inventors: 慶徳林
Original assignee: 株式会社デンソー
Priority date: 2018-08-06
Filing date: 2019-07-02
Publication date: 2020-02-13
Also published as: JP2020025385A; JP6988734B2

Abstract

This control circuit controls the driving of a MOSFET (350) equipped with a wide-gap semiconductor. The control circuit has an off-circuit (507) for discharging a charge stored in the gate electrode (350c) of the MOSFET to a reference voltage level. The off-circuit has: an off-resistor (553) and a first off-switch (554) which are provided in first wiring (540, 551) connecting the gate electrode and the reference voltage level; and a second off-switch (555) provided in second wiring (540, 552) connecting the gate electrode and the reference voltage level.

Description

Control circuit

Cross-reference of related applications

This application is based on Japanese Patent Application No. 2018-147793 filed on Aug. 6, 2018, the contents of which are incorporated herein by reference.

(4) The present disclosure relates to a control circuit that controls driving of a MOSFET.

As described in Non-Patent Document 1, a gate driver that controls driving of a transistor is known. The gate driver has three switches for controlling the connection between the gate electrode of the transistor and the negative power supply (ground).

構成 In the configuration described in Non-Patent Document 1, the number of switches increases, and the physique may increase.

The present disclosure aims to provide a control circuit in which an increase in physique is suppressed.

According to one embodiment of the present disclosure, a control circuit that controls driving of a MOSFET including a wide gap semiconductor is provided. The control circuit has an off circuit for extracting the electric charge accumulated in the gate electrode of the MOSFET to a reference potential. The off circuit includes an off resistor and a first off switch provided on a first wiring connecting the gate electrode and the reference potential, and a second off switch provided on a second wiring connecting the gate electrode and the reference potential. And

According to the configuration of the present disclosure, the number of switches connecting the gate electrode and the reference potential is reduced. This suppresses an increase in the physique of the control circuit.

In the case of the control circuit according to the present disclosure, when the second off switch is changed from the open state to the closed state in a state where electric charge is accumulated in the gate electrode, an instantaneous surge voltage may be generated in the MOSFET. However, MOSFETs have a property of higher avalanche withstand capability than IGBTs, for example. Since MOSFETs are mainly made of wide-gap semiconductors, they also have high withstand capability. Therefore, even if a surge voltage occurs in the MOSFET, damage to the MOSFET is suppressed.

The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description with reference to the accompanying drawings. In the attached drawings,
It is a circuit diagram for explaining an in-vehicle system. FIG. 3 is a circuit diagram for explaining an opening / closing unit and a gate driver. It is a circuit diagram showing a modification of an in-vehicle system.

Hereinafter, embodiments will be described with reference to the drawings.

(1st Embodiment)
(In-vehicle system)
The in-vehicle system 100 will be described based on FIG. This in-vehicle system 100 constitutes a system for an electric vehicle. The in-vehicle system 100 includes a battery 200, a power converter 300, and a motor 400.

The on-board system 100 has a plurality of ECUs. FIG. 1 illustrates a battery ECU 501 and an MGECU 502 as representatives of the plurality of ECUs. These ECUs transmit and receive signals to and from each other via the bus wiring 500. The plurality of ECUs cooperate to control the electric vehicle. Regeneration and power running of the motor 400 according to the SOC of the battery 200 are controlled by the control of the plurality of ECUs. SOC is an abbreviation of state \ of \ charge. ECU is an abbreviation for electronic @ control @ unit.

The ECU has at least one arithmetic processing unit (CPU) and at least one memory device (MMR) as a storage medium for storing programs and data. The ECU is provided by a microcomputer including a computer-readable storage medium. The storage medium is a non-transitional substantial storage medium that temporarily stores a computer-readable program. The storage medium can be provided by a semiconductor memory or a magnetic disk or the like. Hereinafter, components of the in-vehicle system 100 will be individually outlined.

The battery 200 has a plurality of secondary batteries. These plurality of secondary batteries form a battery stack connected in series. The SOC of the battery stack corresponds to the SOC of the battery 200. As the secondary battery, a lithium ion secondary battery, a nickel hydride secondary battery, an organic radical battery, or the like can be used.

The power converter 300 performs power conversion between the battery 200 and the motor 400. Power converter 300 converts the DC power of battery 200 into AC power at a voltage level suitable for powering motor 400. Power converter 300 converts AC power generated by power generation (regeneration) of motor 400 into DC power at a voltage level suitable for charging battery 200. The power converter 300 will be described later in detail.

The motor 400 is connected to an output shaft of an electric vehicle (not shown). The rotational energy of the motor 400 is transmitted to the traveling wheels of the electric vehicle via the output shaft. Conversely, the rotational energy of the running wheels is transmitted to the motor 400 via the output shaft.

The motor 400 runs by the AC power supplied from the power converter 300. As a result, the driving force is applied to the traveling wheels. Further, the motor 400 regenerates by the rotational energy transmitted from the running wheels. The AC power generated by this regeneration is converted into DC power by the power converter 300 and stepped down. This DC power is supplied to battery 200. The DC power is also supplied to various electric loads mounted on the electric vehicle.

(Power converter)
The power converter 300 will be described. The power converter 300 includes a converter 310 and an inverter 320. Converter 310 boosts the DC power of battery 200 to a voltage level suitable for powering motor 400. Inverter 320 converts this DC power into AC power. This AC power is supplied to the motor 400. Inverter 320 converts AC power generated by motor 400 into DC power. Converter 310 reduces this DC power to a voltage level suitable for charging battery 200.

コンバータ As shown in FIG. 1, converter 310 is electrically connected to battery 200 via first power line 301 and second power line 302. Converter 310 is electrically connected to inverter 320 via third power line 303 and fourth power line 304.

The first power line 301 is connected to the positive electrode of the battery 200. Second power line 302 is connected to the negative electrode of battery 200. A first smoothing capacitor 305 is connected to the first power line 301 and the second power line 302. One of the two electrodes of the first smoothing capacitor 305 is connected to the first power line 301, and the other is connected to the second power line 302.

The third power line 303 is connected to the high side opening / closing section 311. The fourth power line 304 is connected to the second power line 302. A second smoothing capacitor 306 is connected to the third power line 303 and the fourth power line 304. One of the two electrodes of the second smoothing capacitor 306 is connected to the third power line 303, and the other is connected to the fourth power line 304.

Inverter 320 is electrically connected to U-phase stator coil 401 to W-phase stator coil 403 of motor 400 via U-phase bus bar 331 to W-phase bus bar 333. The notations U-phase bus bar 331 to W-phase bus bar 333 represent, for example, U-phase bus bar 331, V-phase bus bar 332, and W-phase bus bar 333. The notations U-phase stator coil 401 to W-phase stator coil 403 represent, for example, U-phase stator coil 401, V-phase stator coil 402, and W-phase stator coil 403.

(converter)
Converter 310 has a high-side opening / closing section 311, a low-side opening / closing section 312, and a reactor 313. Each of the high-side opening / closing section 311 and the low-side opening / closing section 312 has an N-channel type power MOSFET. The power MOSFET has a parasitic diode.

(1) As shown in FIG. 1, the high-side opening / closing section 311 and the low-side opening / closing section 312 are connected in series from the third power line 303 to the second power line 302 (fourth power line 304). The first power line 301 is connected to a midpoint between the high side opening / closing section 311 and the low side opening / closing section 312. The reactor 313 is provided on the first power line 301. As a result, the reactor 313 is connected to the midpoint between the high side opening / closing section 311 and the low side opening / closing section 312 and to the positive electrode of the battery 200.

ハイ The high-side opening / closing section 311 and the low-side opening / closing section 312 of the converter 310 are controlled to be opened and closed by the MGECU 502. MGECU 502 generates a control signal and outputs it to gate driver 503. The gate driver 503 amplifies the control signal and outputs it to the gate electrode of the MOSFET provided in the switching unit. Thereby, MGECU 502 raises and lowers the voltage level of the DC power input to converter 310.

MG ECU 502 generates a pulse signal as a control signal. The MGECU 502 adjusts the step-up / step-down level of the DC power by adjusting the on-duty ratio and the frequency of the pulse signal. In this way, the MGECU 502 performs PWM control on the converter 310. The step-up / step-down level is determined according to the target torque of motor 400 and the SOC of battery 200.

When boosting the DC power of the battery 200, the MGECU 502 alternately opens and closes each of the high-side opening and closing unit 311 and the low-side opening and closing unit 312. On the contrary, when the DC power supplied from the inverter 320 is stepped down, the MGECU 502 fixes the control signal output to the low-side opening / closing unit 312 to a low level. At the same time, the MGECU 502 sequentially switches the control signal output to the high-side opening / closing unit 311 between a high level and a low level.

(Inverter)
The inverter 320 has a first opening / closing section 321 to a sixth opening / closing section 326. Each of the first opening / closing section 321 to the sixth opening / closing section 326 has an N-channel type power MOSFET similarly to the opening / closing section of the converter 310. This power MOSFET also has a parasitic diode. The notation of the first opening / closing section 321 to the sixth opening / closing section 326 is, for example, a first opening / closing section 321, a second opening / closing section 322, a third opening / closing section 323, a fourth opening / closing section 324, a fifth opening / closing section 325, and a sixth opening / closing section 325. The opening / closing unit 326 is shown.

The first switch 321 and the second switch 322 are connected in series from the third power line 303 to the fourth power line 304. The first opening / closing section 321 and the second opening / closing section 322 constitute a U-phase leg. One end of the U-phase bus bar 331 is connected to a midpoint between the first opening / closing section 321 and the second opening / closing section 322. The other end of U-phase bus bar 331 is connected to U-phase stator coil 401 of motor 400.

The third switch 323 and the fourth switch 324 are connected in series from the third power line 303 to the fourth power line 304 in order. The third opening / closing section 323 and the fourth opening / closing section 324 form a V-phase leg. One end of a V-phase bus bar 332 is connected to a middle point between the third opening / closing section 323 and the fourth opening / closing section 324. The other end of V-phase bus bar 332 is connected to V-phase stator coil 402 of motor 400.

The fifth switch 325 and the sixth switch 326 are connected in series from the third power line 303 to the fourth power line 304. The fifth opening / closing section 325 and the sixth opening / closing section 326 form a W-phase leg. One end of a W-phase bus bar 333 is connected to a middle point between the fifth opening / closing section 325 and the sixth opening / closing section 326. The other end of W-phase bus bar 333 is connected to W-phase stator coil 403 of motor 400.

As described above, the inverter 320 has three-phase legs corresponding to the U-phase stator coil 401 to the W-phase stator coil 403 of the motor 400, respectively. The control signal of the MGECU 502 amplified by the gate driver 503 is input to the gate electrodes of the first opening / closing section 321 to the sixth opening / closing section 326 constituting these three-phase legs. The notations U-phase stator coil 401 to W-phase stator coil 403 represent, for example, U-phase stator coil 401, V-phase stator coil 402, and W-phase stator coil 403.

When the motor 400 is running, the first opening / closing section 321 to the sixth opening / closing section 326 are PWM-controlled by the output of the control signal from the MGECU 502. Thereby, three-phase alternating current is generated by inverter 320. When the motor 400 generates (regenerates) power, the MGECU 502 stops, for example, outputting a control signal. As a result, the AC power generated by the power generation of the motor 400 passes through the diode of the switching unit. As a result, AC power is converted to DC power.

(Opening and closing part)
The opening / closing unit will be described based on FIG. FIG. 2 shows a second opening / closing section 322 as a representative of the eight opening / closing sections constituting power converter 300. The configuration of the other opening / closing units is the same as the configuration of the second opening / closing unit 322. Therefore, the description is omitted.

The second switching unit 322 has the MOSFET 350. MOSFET 350 is mainly manufactured of a wide gap semiconductor. In the present embodiment, the MOSFET 350 is mainly made of SiC.

The MOSFET 350 is a power transistor formed by connecting thousands of transistors formed on a semiconductor chip. The thousands of transistors are classified into a first transistor that plays a role in controlling the current flowing through the power converter 300 and a second transistor that plays a role in detecting the flowing current.

比 The ratio of the current flowing through the first transistor to the current flowing through the second transistor is approximately 8000: 1. Therefore, the amount of current flowing through the second transistor is very small.

The MOSFET 350 has a drain electrode 350a, a source electrode 350b, a gate electrode 350c, and a sensor electrode 350d. Of these four electrodes, the drain electrode 350a and the gate electrode 350c are shared by the first transistor and the second transistor. On the other hand, the source electrode 350b and the sensor electrode 350d are divided into a first transistor and a second transistor. The first transistor has a source electrode 350b. The second transistor has a sensor electrode 350d. The amount of current flowing through the sensor electrode 350d is smaller than the amount of current flowing through the source electrode 350b. The ratio is 1: 8000. Hereinafter, this ratio is referred to as a sensor ratio. MGECU 502 stores this sensor ratio.

ＭＯＳＦＥＴ As shown in FIG. 2, the MOSFET 350 has a parasitic diode 351. The cathode electrode of the parasitic diode 351 is connected to the drain electrode 350a. The anode electrode of the parasitic diode 351 is connected to the source electrode 350b. As a result, the parasitic diode 351 is connected in anti-parallel to the MOSFET 350.

The sensor electrode 350d of the MOSFET 350 is connected to the ground via the sensor resistor 352. Therefore, a small amount of current flows through the sensor resistor 352 from the sensor electrode 350d to the ground. This small amount of current depends on the current flowing between the drain and source of the MOSFET 350 (drain current).

(4) When a small amount of current flows through the sensor resistor 352, the voltage of the sensor resistor 352 on the sensor electrode 350d side changes. The voltage on the sensor electrode 350d side of the sensor resistor 352 is input to the MGECU 502. The MGECU 502 stores the resistance value of the sensor resistor 352. MGECU 502 detects the drain current based on the input voltage, the stored resistance value, and the sensor ratio. MGECU 502 corresponds to the control unit. The sensor resistance 352 corresponds to a sensor.

(Gate driver)
The gate driver 503 will be described based on FIG. FIG. 2 shows a portion that controls the driving of the second opening / closing section 322 in the gate driver 503. The parts that control the other opening and closing parts of the gate driver 503 are the same as the parts shown in FIG. Therefore, the description is omitted.

(2) Although the MG ECU 502 is not shown in FIG. 2, a reference numeral 600 for clearly indicating a control circuit having the MG ECU 502 and the gate driver 503 is shown. The control circuit 600 has a sensor resistor 352 in addition to the MGECU 502 and the gate driver 503.

The gate driver 503 has an ON circuit 506 and an OFF circuit 507 connected to the gate electrode 350c of the MOSFET 350.

(ON circuit)
The ON circuit 506 includes a control wiring 540, a power supply 541, an ON switch 542, and an ON resistance 543. The power supply 541 and the gate electrode 350c of the MOSFET 350 are connected via the control wiring 540. The control wiring 540 is provided with an on-switch 542 and an on-resistance 543. The on-switch 542 and the on-resistance 543 are connected in series in order from the power supply 541 toward the gate electrode 350c.

The ON switch 542 is a P-channel MOSFET. A drive signal based on a control signal output from MGECU 502 is input to the gate electrode of on switch 542. Thus, the ON switch 542 is ON / OFF controlled.

When the ON switch 542 changes from the OFF state to the ON state, the voltage (power supply voltage) of the power supply 541 whose voltage has been dropped by the ON resistance 543 is applied to the gate electrode 350c. As a result, the MOSFET 350 changes from the off state to the on state. Conversely, when the on switch 542 changes from the on state to the off state, the application of the power supply voltage to the gate electrode 350c stops. This causes the MOSFET 350 to transition from the on state to the off state.

(Off circuit)
The off circuit 507 includes a first reference wiring 551, a second reference wiring 552, an off resistor 553, a first off switch 554, and a second off switch 555. The ON circuit 506 and the OFF circuit 507 share a control wiring 540.

One end of each of the first reference wiring 551 and the second reference wiring 552 is connected between the on-resistance 543 of the control wiring 540 and the gate electrode 350c. The other end of each of the first reference wiring 551 and the second reference wiring 552 is connected to the ground. The other end of each of the first reference wiring 551 and the second reference wiring 552 may be connected to, for example, a negative power supply of −5V.

Ground or negative power supply corresponds to the reference potential. The control wiring 540 and the first reference wiring 551 correspond to the first wiring. The control wiring 540 and the second reference wiring 521 correspond to the second wiring.

(4) The first reference wiring 551 is provided with an off-resistance 553 and a first off switch 554. The off resistor 553 and the first off switch 554 are connected in series from one end of the first reference wiring 551 to the other end.

２A second off switch 555 is provided on the second reference wiring 552. The performance and physique of the first off switch 554 and the second off switch 555 are equivalent. Note that the second reference wiring 552 may be provided with a resistor having a smaller resistance value than the off-resistance 553.

The first off switch 554 and the second off switch 555 are N-channel MOSFETs. A drive signal based on a control signal output from the MGECU 502 is input to the gate electrodes of the first off switch 554 and the second off switch 555. Accordingly, the first off switch 554 and the second off switch 555 are on / off controlled.

(4) When the first off switch 554 is turned on from the off state, the gate electrode 350c is connected to the ground via the off resistance 553. When charge is accumulated in the MOSFET 350, the charge flows to the ground. MOSFET 350 transitions from the on state to the off state.

(4) When the second off switch 555 changes from the off state to the on state, the gate electrode 350c is connected to the ground. As a result, the MOSFET 350 is connected to the ground with low impedance. MOSFET 350 is fixed in the off state.

(On / off control)
The on / off control of the MOSFET 350 by the MG ECU 502 will be described. The MGECU 502 detects whether an abnormality has occurred in the MOSFET 350 based on, for example, a current flowing through the sensor resistor 352. When determining that no abnormality has occurred in the MOSFET 350, the MGECU 502 normally controls the MOSFET 350. When determining that an abnormality has occurred in the MOSFET 350, the MGECU 502 performs emergency control of the MOSFET 350.

(Normal control)
When transitioning the MOSFET 350 from the off state to the on state in the normal control, the MGECU 502 turns on the on switch 542 and turns off the first off switch 554 and the second off switch 555. As a result, a power supply voltage is applied to the gate electrode 350c of the MOSFET 350. Charge is accumulated in the gate electrode 350c of the MOSFET 350. The parasitic capacitance of MOSFET 350 is charged. As a result, the MOSFET 350 is turned on.

(4) When the MOSFET 350 transitions from the ON state to the OFF state in the normal control, the MGECU 502 turns the ON switch 542 OFF, the first OFF switch 554 ON, and the second OFF switch 555 OFF. As a result, the electric charge accumulated in the gate electrode 350c of the MOSFET 350 flows to the ground via the off-resistance 553. MOSFET 350 is turned off.

(4) At this time, the electric charge accumulated in the gate electrode 350c flows to the ground via the off-resistance 553. As a result, the charge slowly flows to the ground. MOSFET 350 makes a gradual transition from the on state to the off state. The time change of the drain current flowing between the drain electrode 350a and the source electrode 350b of the MOSFET 350 becomes slow. Therefore, generation of a surge voltage proportional to the time change of the drain current is suppressed.

@ The MG ECU 502 turns on the second off switch 555 after a lapse of a predetermined time from turning on the first off switch 554. The predetermined time is obtained in advance based on the time required for the MOSFET 350 to switch from the on state to the off state. The predetermined time is stored in the MGECU 502.

(4) Since the second off switch 555 is turned on, the MOSFET 350 is connected to the ground with low impedance. At this time, no drain current flows through MOSFET 350. Therefore, no surge voltage occurs in MOSFET 350.

(Emergency control)
When transitioning the MOSFET 350 from the on state to the off state in the emergency control, the MGECU 502 turns the on switch 542 off and the second off switch 555 on. At this time, the first off switch 554 remains off. When the second off switch 555 is turned on, the electric charge accumulated in the gate electrode 350c of the MOSFET 350 quickly flows to the ground.

(4) At this time, a surge voltage is generated in the MOSFET 350. However, the MOSFET 350 has such a property that avalanche breakdown does not occur when the leakage current is small and the generation time of the surge voltage is short. Therefore, the MOSFET 350 has a higher avalanche withstand capability than, for example, an IGBT. Further, the MOSFET 350 of the present embodiment is manufactured by SiC. Therefore, the MOSFET 350 has a high withstand voltage. For this reason, the damage of the MOSFET 350 due to the generation of the surge voltage is suppressed.

よう As described above, the off circuit 507 has only two off switches. Therefore, a surge voltage may be generated in the MOSFET 350 to be controlled. However, as described above, the MOSFET 350 has a higher avalanche withstand capability than the IGBT. Since the MOSFET 350 is made of SiC, it has a high withstand capability. Therefore, the damage of the MOSFET 350 due to the generation of the surge voltage is suppressed.

Therefore, even if the number of the off switches included in the off circuit 507 becomes two as described above, the occurrence of damage to the MOSFET 350 is suppressed. Due to the decrease in the number of off switches, an increase in the size of the control circuit 600 is suppressed. When the off circuit 507 is formed of, for example, one IC chip, the number of terminals connected to the off switch is reduced. This also suppresses an increase in the physique of the control circuit 600.

In the normal control, the MGECU 502 turns on the first off switch 554 to extract the electric charge of the gate electrode 350c of the MOSFET 350, and then turns on the second off switch 555.

According to this, the gate electrode 350c is connected to the ground via the first off switch 554 in the on state and the off resistor 553. As a result, the charge of the gate electrode 350c is slowly pulled out to the ground. The drain current of MOSFET 350 gradually decreases. Thereafter, the gate electrode 350c is connected to the ground via the second off switch 555 in the on state. This suppresses generation of a surge voltage in the MOSFET 350, and connects the gate electrode 350c to the ground with low impedance.

において In the emergency control, the MGECU 502 turns the second off switch 555 on.

(4) In this case, the charge of the gate electrode 350c is quickly pulled out to the ground. The drain current of MOSFET 350 sharply decreases. As a result, a surge voltage is generated in MOSFET 350.

(4) For example, when the abnormality of the energization state is an increase in the amount of energization current, the surge voltage generated in the MOSFET 350 increases. However, the surge voltage generated at this time is instantaneous. As described above, the MOSFET has a higher avalanche withstand capability than the IGBT. Since the MOSFET 350 is made of SiC, it has a high withstand capability. For this reason, even if a surge voltage occurs in the MOSFET 350, the occurrence of damage to the MOSFET 350 is suppressed.

異常 Such anomalies are not expected to occur many times. Even if a surge voltage is generated in the MOSFET 350 by the control at the time of occurrence of one or several degrees of abnormality, it is assumed that the possibility of damage to the MOSFET 350 due to the surge voltage is unlikely to increase.

MOSFET 350 is made of SiC. Therefore, the turn-on delay time and the turn-off delay time of the MOSFET 350 are shortened. Thereby, switching loss generated in MOSFET 350 is reduced.

(2nd Embodiment)
A second embodiment will be described. The circuit configuration according to each embodiment described below has many points in common with those according to the above-described embodiments. Therefore, the description of the common parts will be omitted below, and different parts will be mainly described. In the following, the same elements as those described in the above embodiment are denoted by the same reference numerals.

In the first embodiment, an example has been described in which the charge of the gate electrode 350c of the MOSFET 350 is extracted via the first off switch 554 in the normal control. On the other hand, in the present embodiment, in the normal control, the charge of the gate electrode 350c of the MOSFET 350 is extracted via the second off switch 555.

際 Drain current is flowing through the MOSFET 350 when the charge of the gate electrode 350c is extracted. Therefore, when the second off switch 555 is turned on, a surge voltage is generated in the MOSFET 350.

However, during normal control, the amount of drain current flowing through MOSFET 350 is not excessive enough to determine that MGECU 502 is abnormal. The MOSFET 350 has a high withstand voltage. Therefore, the occurrence of damage to MOSFET 350 due to the generation of the surge voltage is suppressed.

In the first embodiment, an example has been described in which the charge of the gate electrode 350c of the MOSFET 350 is extracted through the second off switch 555 in the emergency control. On the other hand, in the present embodiment, in the emergency control, the charge of the gate electrode 350c of the MOSFET 350 is extracted via the first off switch 554.

In this case, the electric charge accumulated in the gate electrode 350c flows to the ground via the off-resistance 553. Therefore, the transition from the ON state to the OFF state of the MOSFET 350 becomes gentle. Even if an abnormality in which a large current flows through the MOSFET 350 occurs, the time change of the drain current flowing through the MOSFET 350 is prevented from becoming steep. Thus, generation of a surge voltage in MOSFET 350 is suppressed.

The MGECU 502 turns on the second off switch 555 after the electric charge accumulated in the gate electrode 350c is drawn to the ground. As a result, the gate electrode 350c is connected to the ground with low impedance. When the other end of each of the first reference wiring 551 and the second reference wiring 552 is connected to a negative power supply, the second off switch 555 does not need to be turned on.

This configuration also has components equivalent to those of the various embodiments described above and performs the same operations. Therefore, the same operation and effect can be obtained.

Although the preferred embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments and can be implemented in various modifications without departing from the gist of the present disclosure.

(First Modification)
An example has been shown in which each of the eight opening / closing sections constituting the power converter 300 has a MOSFET 350. However, the switching unit may include, for example, an IGBT connected in parallel to the MOSFET 350 in addition to the MOSFET 350.

The IGBT has a lower withstand voltage against a surge voltage than the MOSFET 350. Therefore, an off circuit that connects the gate electrode of the IGBT to the ground has three off switches and two off resistances. For the sake of simplicity, these three off switches are hereinafter referred to as a third off switch, a fourth off switch, and a fifth off switch. The two off-resistances are referred to as a second off-resistance and a third off-resistance. The third off-resistance has a higher resistance value than the second off-resistance.

A third off switch and a second off resistor are connected in series between the gate electrode of the IGBT and the ground. A fourth off switch and a third off resistance are connected in series between the gate electrode of the IGBT and the ground. A fifth off switch is provided between the gate electrode of the IGBT and the ground.

When the IGBT is turned off during normal control, the MGECU 502 turns on the third off switch, slowly pulls the electric charge to the ground, and then turns on the fifth off switch. When the IGBT is turned off during the emergency control, the MGECU 502 turns on the fourth off switch, slowly pulls the electric charge to the ground, and then turns on the fifth off switch. By the control described above, the generation of the surge voltage in the IGBT is suppressed, and the gate electrode of the IGBT is connected to the ground with low impedance.

In the case where the switching unit has two MOSFETs 350 connected in parallel, the off-circuit 507 described above is individually connected to the gate electrode 350c of each of the two MOSFETs 350. Alternatively, one common off circuit 507 is connected to the gate electrode 350c of each of the two MOSFETs 350.

(Other modifications)
In each embodiment, as an example of the gate driver included in the control circuit 600, the gate driver 503 of the power converter 300 included in the in-vehicle system for the electric vehicle has been described. However, application of the gate driver included in the control circuit 600 is not particularly limited to the above example. For example, the present invention can be applied to a gate driver of a power converter of a hybrid system including a motor and an internal combustion engine.

In each embodiment, the example in which the power converter 300 has one converter 310 and one inverter 320 has been described. However, for example, in the case where the in-vehicle system 100 has two motors 400 as shown in FIG. 3, a configuration in which the power converter 300 has one converter 310 and two inverters 320 can be adopted.

では In each embodiment, an example has been described in which the control circuit 600 includes the MGECU 502, the gate driver 503, and the sensor resistor 352. However, the control circuit 600 may include only the gate driver 503 to solve the problem of suppressing an increase in physique.

As described above, the embodiment, the configuration, and the aspect of the control circuit according to an embodiment of the present disclosure have been illustrated. Not something. For example, embodiments, configurations, and aspects obtained by appropriately combining technical portions disclosed in different embodiments, configurations, and aspects are also included in the scope of the embodiments, configurations, and aspects according to the present disclosure.

Claims

A control circuit for controlling driving of a MOSFET (350) including a wide gap semiconductor,
An off circuit (507) for extracting electric charges accumulated in the gate electrode (350c) of the MOSFET to a reference potential;
The off circuit,
An off-resistance (553) and a first off-switch (554) provided on a first wiring (540, 551) connecting the gate electrode and the reference potential;
A second off switch (555) provided on a second wiring (540, 552) connecting the gate electrode and the reference potential.
A control unit (502) that controls driving of the first off switch and the second off switch;
A sensor (352) for detecting an energized state of the MOSFET,
The control unit includes:
When no abnormality occurs in the energized state, the first off switch is turned on,
The control circuit according to claim 1, wherein when an abnormality occurs in the energization state, the second off switch is turned on.
A control unit (502) that controls driving of the first off switch and the second off switch;
A sensor (352) for detecting an energized state of the MOSFET,
The control unit includes:
If no abnormality has occurred in the energized state, the second off switch is turned on,
The control circuit according to claim 1, wherein the first off switch is turned on when an abnormality occurs in the energized state.