WO2015182038A1

WO2015182038A1 - Rc-igbt drive circuit

Info

Publication number: WO2015182038A1
Application number: PCT/JP2015/002229
Authority: WO
Inventors: 昌弘山本; 岩村　剛宏
Original assignee: 株式会社デンソー
Priority date: 2014-05-27
Filing date: 2015-04-24
Publication date: 2015-12-03
Also published as: JP2015226142A; JP6337615B2

Abstract

This RC-IGBT drive circuit is provided with: a plurality of switch circuits (SW2-SW6) connected between any from among a second gate terminal (9), an emitter terminal (11), and capacitor connection terminals (13); and a control circuit (3). When an RC-IGBT is turned off, the control circuit controls the on-off states of the plurality of switch circuits, and, as a result, forms a charging path which causes the electric charge charging a capacitor between a second gate and an emitter of the RC-IGBT to charge a capacitative element, and subsequently forms a negative voltage application path respectively connecting, to the emitter and the second gate, a positive-potential-side terminal and a negative-potential-side terminal of the capacitative element.

Description

RC-IGBT drive circuit

Cross-reference of related applications

This disclosure is based on Japanese Patent Application No. 2014-109055 filed on May 27, 2014, the contents of which are incorporated herein.

The present disclosure relates to a drive circuit that drives a reverse conducting insulated gate bipolar transistor (RC-IGBT) that can be turned off at high speed by including two gate electrodes.

Patent Document 1 discloses an RC-IGBT (hereinafter simply referred to as IGBT) having two gate electrodes. When the IGBT is turned on, a turn-on voltage is applied to both gate electrodes. When the IGBT is turned off, a turn-off voltage is applied to one gate electrode and then a turn-off voltage is applied to the other gate electrode. As a result, turn-off can be performed at a higher speed.

In order to turn off the IGBT in Patent Document 1 at high speed, it is desirable to apply a negative voltage to one gate electrode. However, if a separate negative power supply is prepared for this purpose, the cost increases and the drive loss also increases.

JP 2013-98415 A

It is an object of the present disclosure to provide an RC-IGBT driving circuit that can quickly turn off an RC-IGBT without using a negative power supply.

In the RC-IGBT drive circuit according to one aspect of the present disclosure, when the RC-IGBT including the first gate and the second gate is a driving target and the RC-IGBT is turned off from the turned-on state, An RC-IGBT driving circuit for applying a turn-off voltage to the first gate after applying a negative turn-off voltage to the second gate, the second gate terminal, an emitter terminal, two capacitance connection terminals, A plurality of switch circuits and a control circuit.

The second gate terminal is connected to the second gate. The emitter terminal is connected to the emitter of the RC-IGBT. A capacitor element is connected to the capacitor connection terminal. The plurality of switch circuits are connected between any of the second gate terminal, the emitter terminal, and the capacitor connection terminal. When the RC-IGBT is turned off by controlling on / off of the plurality of switch circuits, the control circuit transfers the charge charged in the second gate-emitter capacitance of the RC-IGBT to the capacitive element. After forming a charging path for charging, a negative voltage application path for connecting the positive potential side terminal and the negative potential side terminal of the capacitive element to the emitter and the second gate is formed.

The RC-IGBT drive circuit charges the capacitor element with the charge charged in the second gate-emitter capacitor of the RC-IGBT that is turned on, and then reverses the charge to the capacitor element. The second gate can be set to a negative voltage by connecting to the emitter and the second gate of the RC-IGBT so as to be polar. Therefore, even if a power supply for applying a negative voltage is not separately prepared, the second gate of the RC-IGBT can be set to a negative voltage for fast turn-off.

The above and other objects, configurations, and advantages of the present disclosure will become more apparent from the following detailed description with reference to the following drawings. In the drawing
FIG. 1 is a diagram showing a configuration of an RC-IGBT drive circuit according to the first embodiment. FIG. 2A is a diagram showing an on / off state of each switch circuit in phase IIA of the turn-off sequence according to the first embodiment. FIG. 2B is a diagram illustrating an on / off state of each switch circuit in phase IIB of the turn-off sequence according to the first embodiment. FIG. 2C is a diagram showing an on / off state of each switch circuit in phase IIC of the turn-off sequence according to the first embodiment. FIG. 2D is a diagram illustrating an on / off state of each switch circuit in the phase IID of the turn-off sequence according to the first embodiment. FIG. 2E is a diagram showing an on / off state of each switch circuit in phase IIE of the turn-off sequence according to the first embodiment. FIG. 3 is a timing chart corresponding to FIGS. 2A to 2E. FIG. 4 is a timing chart including a turn-on operation. FIG. 5A is a diagram illustrating an on / off state of each switch circuit in the phase VA of the turn-off sequence according to the second embodiment. FIG. 5B is a diagram showing an on / off state of each switch circuit in the phase VB of the turn-off sequence according to the second embodiment. FIG. 5C is a diagram illustrating an on / off state of each switch circuit in the phase VC of the turn-off sequence according to the second embodiment. FIG. 5D is a diagram illustrating an on / off state of each switch circuit in the phase VD of the turn-off sequence according to the second embodiment. FIG. 6 is a timing chart corresponding to FIGS. 5A to 5D. FIG. 7 is a diagram showing a configuration of an RC-IGBT drive circuit according to the third embodiment. FIG. 8 is a diagram illustrating a specific configuration of each switch circuit of the control gate driving unit according to the fourth embodiment. FIG. 9 is a diagram illustrating a specific configuration of each switch circuit of the control gate driving unit according to the fifth embodiment. FIG. 10 is a diagram illustrating a specific configuration of each switch circuit of the control gate driving unit according to the sixth embodiment. FIG. 11A is a timing chart when the IGBTs are alternately turned on and turned off in the seventh embodiment. FIG. 11B is a timing chart when the IGBTs are alternately turned on and turned off in the second embodiment.

(First embodiment)
The drive circuit 1 according to the first embodiment of the present disclosure will be described with reference to FIGS. As shown in FIG. 1, the drive circuit 1 of this embodiment includes an RC-IGBT (hereinafter simply referred to as IGBT) 2 including a main gate G (first gate) and a control gate CG (second gate). The IGBT 2 to be driven is the same as the semiconductor device disclosed in Patent Document 1. That is, as shown in FIG. 4, when the PWM control signal becomes a high level and the IGBT 2 is turned on, a turn-on voltage (high level drive voltage) is applied to the main gate G and the control gate CG simultaneously.

On the other hand, when the PWM control signal becomes low level and the IGBT 2 is turned off, the potential of the control gate CG is first lowered (0V → negative voltage) and then the turn-off voltage (low level driving voltage) is applied to the main gate G. Control to do. Thus, by lowering the potential of the control gate CG first, some of the holes or electrons accumulated in the drift layer are extracted in advance, and therefore remain when the turn-off voltage is applied to the main gate G. The extraction of holes or electrons is completed in a short time (see Patent Document 1, paragraph [0013]). Therefore, the switching speed of the IGBT 2 is improved, and loss can be reduced.

The drive circuit 1 includes a control signal generation unit 3 (control circuit), a control gate drive unit 4 and a main gate drive unit 5. The drive circuit 1 is supplied with a drive power supply 7 (voltage VB, for example, about 20 V) via a power supply terminal 6, and PWM is supplied from the outside (a microcomputer as a host control device) via a signal input terminal 8. A control signal is input. The control

gate connection terminals

9a and 9b (second gate terminals) of the drive circuit 1 are connected to the control gate CG via external resistance elements RGP and RGN, respectively. The main gate connection terminals 10a and 10b are connected to the main gate G through external resistance elements RGP and RGN, respectively. The resistance values of the resistance elements RGP and RGN are appropriately determined according to the settings of the turn-on and turn-off speeds of the gates CG and G.

The emitter connection terminal 11 (emitter terminal) is connected to the emitter of the IGBT 2 and the ground terminal 12 is connected to the ground. However, since the emitter is connected to the ground, the emitter connection terminal 11 and the ground terminal 12 have the same potential. Yes. A capacitor 14 (capacitance element) is externally connected to the

capacitance connection terminals

13a and 13b.

In the control gate driver 4, the switch circuit SW1 is connected between the power supply terminal 6 and the control gate connection terminal 9a, and the switch circuit SW2 (first switch circuit) is connected to the control gate connection terminal 9b and the emitter connection terminal. 11 is connected. The switch circuit SW3 (second switch circuit) is connected between the control gate connection terminal 9b and the capacitor connection terminal 13a, and the switch circuit SW4 (fifth switch circuit) is connected to the capacitor connection terminal 13b and the emitter connection terminal 11. Connected between and. The switch circuit SW5 (third switch circuit) is connected between the control gate connection terminal 9b and the capacitor connection terminal 13b, and the switch circuit SW6 (fourth switch circuit) is connected to the capacitor connection terminal 13a and the emitter connection terminal 11. Connected between and.

In the main gate drive unit 5, the switch circuit SW7 is connected between the power supply terminal 6 and the main gate connection terminal 10a, and the switch circuit SW8 is connected between the main gate connection terminal 10b and the ground terminal 12. ing. A PWM control signal is input to the control signal generation unit 3 via the signal input terminal 8, and the control signal generation unit 3 controls on / off of each of the switch circuits SW1 to SW8 according to the change of the PWM control signal.

Next, the turn-off sequence of this embodiment will be described. When the PWM control signal becomes high level to turn on the IGBT 2, the control signal generation unit 3 turns on the switch circuits SW1 and SW7. As a result, the gate capacitance on the main gate G side and the gate capacitance on the control gate CG side are charged to the voltage VB via the respective resistance elements RGP (see Phase IIA in FIGS. 2A and 3). Since the charge is from 0V to 20V, the drive loss is the same as that of the positive voltage drive.

When the PWM control signal becomes a low level and turns off the IGBT 2, the control signal generator 3 turns off the switch circuit SW1 and then turns on the switch circuits SW3 and SW4. Then, the capacitor 14 is charged by the charge charged in the gate capacitance on the control gate CG side (see Phase IIB in FIG. 2B and FIG. 3).

Next, the control signal generator 3 turns off the switch circuits SW3 and SW4 and then turns on the switch circuit SW2. As a result, the voltage of the control gate CG becomes 0 V, which is the same potential as the emitter (see Phase IIC in FIGS. 2C and 3).

Subsequently, the switch circuit SW2 is turned off and then the switch circuits SW5 and SW6 are turned on. Then, the positive potential side terminal (+) of the capacitor 14 is connected to the emitter, and the negative potential side terminal (−) is connected to the control gate CG. As a result, a negative voltage is applied to the control gate CG (see the phase IID in FIGS. 2D and 3).

At this time, the control signal generator 3 turns off the switch circuit SW7 and then turns on the switch circuit SW8 to discharge the capacitance on the main gate G side and turn off the IGBT2.

Finally, after turning off the switch circuits SW5 and SW6, the switch circuit SW2 is turned on and the potential of the control gate CG is set to 0 V, thereby completing the turn-off sequence (see Phase IIE in FIGS. 2E and 3).

Incidentally, in the step shown in FIG. 2D, when a negative voltage applied to the control gate CG and V _∞, is expressed by the following equation. Note that the negative voltage _V∞ is a voltage when it is assumed that the time has passed infinitely in the phase IID. Capacity _{C CHG} of the capacitor 14 and the capacitance of the control gate CG and _{C CG,}

It becomes. Then, as described in the above formula, in order to turn off the IGBT 2 in a stable state, assuming that the negative voltage is set to V _∞ approximately ½ of the drive power supply voltage VB, C _CHG >> C _CG For this purpose, for example, it is sufficient to set the capacity C _CHG to 10 times the capacity C _CG or more.

As described above, according to the present embodiment, the drive circuit 1 includes the plurality of switch circuits SW2 to SW2 connected between any one of the control

gate connection terminals

9a and 9b, the emitter connection terminal 11, and the

capacitance connection terminals

13a and 13b. SW6 is provided. Then, the control signal generation unit 3 controls on / off of the plurality of switch circuits SW2 to SW6, and when the IGBT 2 is turned off from the turned on state, the charge charged in the capacitance between the control gate CG and the emitter is After forming a charging path for charging the capacitor 14 connected to the

capacitor connection terminals

13a and 13b, the positive potential side terminal and the negative potential side terminal of the capacitor 14 are connected to the emitter and the second gate, respectively. An application path is formed.

As a result, after charging the capacitor 14 with the charge charged in the capacitance between the control gate CG and the emitter of the IGBT 2 that is turned on, the capacitor 14 is connected to the emitter and control of the IGBT 2 so that the charged charge has a reverse polarity. By connecting to the gate CG, the control gate CG can be set to a negative voltage. Therefore, the IGBT 2 can be turned off at high speed without separately preparing a power supply for applying a negative voltage.

Specifically, the switch circuit SW2 is connected between the control gate connection terminal 9b and the emitter connection terminal 11, and the switch circuit SW3 is connected between the control gate connection terminal 9b and the capacitor connection terminal 13a, thereby connecting the control gate. The switch circuit SW5 is connected between the terminal 9b and the capacitor connection terminal 13b, the switch circuit SW6 is connected between the capacitor connection terminal 13a and the emitter connection terminal 11, and between the capacitor connection terminal 13b and the emitter connection terminal 11. Is connected to the switch circuit SW4.

Then, the control signal generation unit 3 turns on the switch circuits SW3 and SW4 to form a charging path, and charges the capacitor element with the charge charged in the control gate CG. Then, when the switch circuits SW3 and SW4 are turned off, the switch circuit SW2 is turned on, and the control gate CG is set to 0 V having the same potential as the emitter. Thereafter, when the switch circuit SW2 is turned off, the switch circuits SW5 and SW6 are turned on to form a negative voltage application path, and the control gate CG is set to a negative voltage.

As a result, after the charge of the control gate CG is discharged, the control gate CG is once set to 0 V and then set to a negative voltage. Therefore, the negative potential of the control gate CG can be increased, and the IGBT 2 can be turned off faster. Can be done. In addition, after the control gate CG is set to a negative voltage, the switch circuits SW5 and SW6 are turned off and then the switch circuit SW2 is turned on, so that the potential of the control gate CG is set to 0V. Can be done to drive loss.

(Second Embodiment)
Hereinafter, the same parts as those in the first embodiment are denoted by the same reference numerals, description thereof will be omitted, and different parts will be described. As shown in FIGS. 5A to 5D and FIG. 6, the turn-off sequence of the second embodiment is obtained by deleting phase IIC from the turn-off sequence of the first embodiment. Phase VA in FIGS. 5A and 6 corresponds to phase IIA in FIGS. 2A and 3, phase VB in FIGS. 5B and 6 corresponds to phase IIB in FIGS. 2B and 3, and phase VC in FIGS. 5C and 6. Corresponds to the phase IID in FIGS. 2D and 3, and the phase VD in FIGS. 5D and 6 corresponds to the phase IIE in FIGS. 2E and 3. When the capacitor 14 is charged in the phase VB, a negative voltage is immediately applied to the control gate CG without setting the potential of the control gate CG to 0 V in the next phase VC.

According to the second embodiment, the control signal generator 3 can easily control each switch circuit. However, since the negative voltage is applied from the state where the potential of the control gate CG exceeds 0 V, the negative potential applied is smaller than that in the first embodiment.

(Third embodiment)
As shown in FIG. 7, the drive circuit 21 of the third embodiment adds a switch circuit SW9 between the power supply terminal 6 and the capacitor connection terminal 13a, and the control signal generation unit 22 replacing the control signal generation unit 3 includes: The on / off of the switch circuit SW9 is also controlled. Before the IGBT 2 is turned on for the first time, the control signal generator 22 turns on the switch circuits SW9 and SW4 to form a startup charging path so that the capacitor 14 is charged to a preset voltage. As a result, a negative voltage having a sufficient potential can be applied to the control gate CG from the first turn-off sequence, and the turn-off sequence can be stably performed.

(Fourth embodiment)
As shown in FIG. 8, the control gate drive unit 31 of the fourth embodiment shows a specific configuration of the switch circuits SW1 to SW6. The switch circuit SW1 is composed of a P-channel MOSFET M1, and the switch circuit SW6 is composed of an N-channel MOSFET M6. The other switch circuits SW2 to SW5 are each constituted by a bidirectional switch in which the sources of two N-channel MOSFETs are connected in common (M21 and M22, M31 and M32, M41 and M42, M51 and M52, respectively). Although not shown, the switch circuit SW7 of the main gate driving unit 5 may be a P-channel MOSFET and the switch circuit SW8 may be an N-channel MOSFET.

(Fifth embodiment)
As shown in FIG. 9, the control gate drive unit 32 of the fifth embodiment has a switch circuit SW2 in the control gate drive unit 31 of the fourth embodiment connected in series in the opposite direction to the N-channel MOSFET M21 and its parasitic diode. Similarly, the switch circuit SW4 includes an N-channel MOSFET M41 and a diode D4 connected in series in the opposite direction to the parasitic diode. The switch circuits SW2 and SW4 replaced in this way are realized with a simple circuit configuration, although the potential of the negative voltage applied to the control gate CG is reduced by the forward voltage of the diodes D2 and D4 compared to the bidirectional switch. it can.

(Sixth embodiment)
As shown in FIG. 10, the control gate drive unit 33 of the sixth embodiment is obtained by replacing the switch circuit SW2 in the control gate drive unit 31 of the fourth embodiment with a resistance element R2. With this configuration, for example, in the phases IIC and IIE in the timing chart shown in FIG. 3, the speed when discharging the control gate CG is slower than that of the first embodiment due to the time constant including the resistance value of the resistance element R2. However, it can be realized with a simple circuit configuration.

(Seventh embodiment)
For example, in the first and second embodiments, the switch circuit SW2 is turned on and the control gate CG is set to 0 V at the end of the turn-off operation. However, in the seventh embodiment, the switch circuit SW2 is not turned on last and the next turn-on is performed. Take action immediately. FIG. 11B shows a case where the IGBTs 2 are alternately turned on and turned off in the second embodiment. In contrast, in the seventh embodiment, when the switch circuits SW5 and SW6 are turned off from the phase VC shown in FIG. 6, the switch circuit SW7 is immediately turned on and the IGBT 2 is turned on as shown in FIG. 11A. According to the seventh embodiment as described above, the turn-off control can be simplified.

The present disclosure is not limited to the embodiment described above or illustrated in the drawings, and the following modifications or expansions are possible.

For example, the drive power supply voltage is not limited to 20V. It is not always necessary to provide the turn-on resistance element RGP and the turn-off resistance element RGN, and a common resistance element may be used if there is no problem in the respective operation speeds. A CMOS transfer gate may be used for the switch circuit. The capacity of the capacitor 14 is not necessarily limited to 10 times or more of the capacity of the control gate CG, and may be appropriately changed according to the individual design.

Claims

When the reverse conducting insulated gate bipolar transistor (RC-IGBT) (2) including the first gate (G) and the second gate (CG) is driven, and the RC-IGBT is turned off from the turn-on state. Is an RC-IGBT driving circuit that applies a turn-off voltage to the first gate after a negative turn-off voltage is applied to the second gate,
A second gate terminal (9) connected to the second gate;
An emitter terminal (11) connected to the emitter of the RC-IGBT;
Two capacitor connection terminals (13a, 13b) to which the capacitor element is connected;
A plurality of switch circuits (SW2 to SW6) connected between any one of the second gate terminal, the emitter terminal, and the capacitor connection terminal;
When the RC-IGBT is turned off by controlling on / off of the plurality of switch circuits, a charge path for charging the capacitor element with the charge charged in the second gate-emitter capacitor of the RC-IGBT And a control circuit (3) for forming a negative voltage application path for connecting the positive potential side terminal and the negative potential side terminal of the capacitive element to the emitter and the second gate, respectively. Driving circuit.
The plurality of switch circuits are:
A first switch circuit (SW2) connected between the second gate terminal and the emitter terminal;
A second switch circuit (SW3) connected between the second gate terminal and one of the capacitor connection terminals;
A third switch circuit (SW5) connected between the second gate terminal and the other of the capacitor connection terminals;
A fourth switch circuit (SW6) connected between one of the capacitor connection terminals and the emitter terminal;
The RC-IGBT drive circuit according to claim 1, further comprising a fifth switch circuit (SW4) connected between the other of the capacitor connection terminals and the emitter terminal.
The control circuit turns on the second switch circuit and the fifth switch circuit to form the charging path,
When the second switch circuit and the fifth switch circuit are turned off, the first switch circuit is turned on,
3. The RC-IGBT drive circuit according to claim 2, wherein when the first switch circuit is turned off, the third switch circuit and the fourth switch circuit are turned on to form the negative voltage application path.
The control circuit turns on the second switch circuit and the fifth switch circuit to form the charging path,
3. The RC-IGBT drive circuit according to claim 2, wherein when the second switch circuit and the fifth switch circuit are turned off, the third switch circuit and the fourth switch circuit are turned on to form the negative voltage application path.
5. The RC-IGBT drive circuit according to claim 3, wherein the control circuit turns on the first switch circuit when the third switch circuit and the fourth switch circuit are turned off.
The RC circuit according to any one of claims 2 to 5, wherein the control circuit (22) forms a start-up charging path for charging the capacitive element to a set voltage by a driving power supply before turning on the RC-IGBT. -IGBT drive circuit.
A sixth switch circuit (SW9) connected between a power supply terminal to which a drive power supply is connected and a capacitor connection terminal that becomes the positive potential side terminal when the charging path is formed;
The control circuit (22) turns on the fifth switch circuit and the sixth switch circuit before turning on the RC-IGBT, and sets up a startup charging path for charging the capacitive element to a set voltage by the driving power supply. The RC-IGBT drive circuit according to any one of claims 2 to 5, which is formed.
Each of the first switch circuit, the second switch circuit, the third switch circuit, and the fifth switch circuit includes two MOSFETs (M21 and M22, M31 and M32, M41 and M42, M51 and M52), and a parasitic diode. 8. The RC-IGBT drive circuit according to claim 2, wherein the RC-IGBT drive circuit is configured by switch circuits connected in series so as to be opposite to each other.
Each of the second switch circuit and the third switch circuit is constituted by a switch circuit in which two MOSFETs (M31 and M32, M51 and M52) are connected in series so that the parasitic diodes are opposite to each other.
At least one of the first switch circuit and the fifth switch circuit is a switch comprising a MOSFET (M21, M41) and a diode (D2, D4) connected in series to the MOSFET in a direction opposite to the parasitic diode of the MOSFET. 8. The RC-IGBT drive circuit according to claim 2, wherein the RC-IGBT drive circuit is configured by a circuit.
A resistance element (R2) connected between the second gate terminal and the emitter terminal;
The plurality of switch circuits are:
A first switch circuit (SW3) connected between the second gate terminal and one of the capacitor connection terminals;
A second switch circuit (SW5) connected between the second gate terminal and the other of the capacitor connection terminals;
A third switch circuit (SW6) connected between one of the capacitor connection terminals and the emitter terminal;
The RC-IGBT drive circuit according to claim 1, comprising a fourth switch circuit (SW4) connected between the other of the capacitor connection terminals and the emitter terminal.
The control circuit turns on the first switch circuit and the fourth switch circuit to form the charging path,
When the first switch circuit and the fourth switch circuit are turned off, the second switch circuit and the third switch circuit are turned on to form the negative voltage application path,
The RC-IGBT drive circuit according to claim 10, wherein the second switch circuit and the third switch circuit are controlled to be turned off.
The RC-IGBT drive circuit according to any one of claims 1 to 11, wherein a capacitive element having a capacitance of 10 times or more of the second gate-emitter capacitance is connected to the capacitance connection terminal.