CN108134510B

CN108134510B - IGBT drive circuit

Info

Publication number: CN108134510B
Application number: CN201611091639.0A
Authority: CN
Inventors: 李广大; 胡朝峰; 殷岳; 周三国; 翟辉冬; 宋菊
Original assignee: SAIC Motor Corp Ltd
Current assignee: SAIC Motor Corp Ltd
Priority date: 2016-12-01
Filing date: 2016-12-01
Publication date: 2020-10-27
Anticipated expiration: 2036-12-01
Also published as: CN108134510A

Abstract

An IGBT drive circuit comprising: the signal isolation circuit is suitable for being externally connected with a control voltage and isolating the control voltage to obtain a first control voltage; the amplifying circuit is suitable for amplifying the first control voltage, and the output end of the amplifying circuit outputs a second control voltage; and the signal conditioning circuit is suitable for generating a third control voltage according to the second control voltage so as to control the IGBT to be turned on and off, and the third control voltage is configurable. The technical scheme of the invention can enlarge the application range of the IGBT driving circuit.

Description

IGBT drive circuit

Technical Field

The invention relates to the field of integrated circuits, in particular to an IGBT driving circuit.

Background

With the rapid development of hybrid electric vehicles and pure electric vehicles, the effective and reliable control of the motor on the vehicle is the guarantee of the normal and safe operation of the vehicle. Insulated Gate Bipolar Transistors (IGBTs) dominate in frequency conversion device applications. The IGBTs may provide energy to the electric machine of the hybrid system. The IGBT is a composite device of an MOSFET tube and a bipolar transistor, has the advantages of easy driving of the MOSFET and large voltage and current capacity of the power transistor, has frequency characteristics between the MOSFET tube and the power transistor, and can normally work in a frequency range of tens of kilohertz. In order to make the IGBT work safely and reliably, its gate should be connected to a driving circuit matched with it. The IGBT driving circuit is difficult and critical to design of an application scheme thereof. The drive circuit with excellent performance is a necessary condition for ensuring the efficient and reliable operation of the IGBT, and particularly has higher requirements on the anti-interference performance and the reliability of the drive circuit on vehicles running in complex electrical environment and road condition conditions.

The typical IGBT driving circuit in the prior art has a protection function for the driving power supply, but the driving voltage supplied to the IGBT is invariable and does not exceed-7.5V.

The non-variability of the driving voltage output by the prior art IGBT driving circuits leads to limitations in the application of these circuits. In the application occasions with larger interference, such as vehicle starting or emergency braking, the IGBT may not be reliably turned off and mistakenly turned on, so that the motor is not normally operated to cause accidents; when the IGBT modules with different power levels are used, the type-selection driving system is often required to be redesigned, and the cost is increased.

Disclosure of Invention

The technical problem solved by the invention is how to enlarge the application range of the IGBT driving circuit.

In order to solve the above technical problem, an embodiment of the present invention provides an IGBT driving circuit, including:

the signal isolation circuit is suitable for being externally connected with a control voltage and isolating the control voltage to obtain a first control voltage; the amplifying circuit is suitable for amplifying the first control voltage, and the output end of the amplifying circuit outputs a second control voltage; and the signal conditioning circuit is suitable for generating a third control voltage according to the second control voltage so as to control the IGBT to be turned on and off, and the third control voltage is configurable.

Optionally, the signal conditioning circuit includes: a first resistor, a first end of which is connected to a power supply voltage; the first end of the second resistor is coupled with the second end of the first resistor, and the second end of the fourth resistor is grounded; a first transistor, a base of which is coupled to the second end of the first resistor, one end of which is connected to the power voltage, and the other end of which is used as an output end of the signal conditioning circuit to output the third control voltage; and a base of the second transistor is coupled to the second end of the third resistor, one end of the second transistor is coupled to the other end of the first transistor, and the other end of the second transistor is grounded.

Optionally, the signal conditioning circuit further includes: a first end of the fifth resistor is coupled with the power supply voltage; a sixth resistor, a first end of which is coupled to the second end of the fifth resistor, and a second end of which is grounded; a seventh resistor having a first end connected to the power supply voltage; a cathode of the first diode is coupled to the second end of the seventh resistor and serves as a first output end of the signal conditioning circuit; and the cathode of the second diode is coupled with the anode of the first diode, and the anode of the second diode is coupled with the second end of the fifth resistor and is used as the second output end of the signal conditioning circuit.

Optionally, the signal conditioning circuit further includes: a third diode having a cathode connected to the power supply voltage; a first end of the first capacitor is coupled with the anode of the third diode; a first end of the eighth resistor is coupled to the second end of the first capacitor, and a second end of the eighth resistor is coupled to the output end of the amplifying circuit; a ninth resistor, a first end of which is coupled to the output end of the amplifying circuit; a first end of the second capacitor is coupled to the second end of the ninth resistor; and the cathode of the fourth diode is coupled with the second end of the second capacitor, and the anode of the fourth diode is grounded.

The optional IGBT drive circuit further comprises: and the switch control circuit is suitable for being coupled with the first output end and the second output end of the signal conditioning circuit and respectively generating a fourth control voltage and a fifth control voltage according to the voltages output by the first output end and the second output end of the signal conditioning circuit so as to respectively control the on-off of the IGBT.

Optionally, the switch control circuit includes a first MOS transistor and a second MOS transistor; the grid electrode of the first MOS tube is coupled with the first output end of the signal conditioning circuit, one end of the first MOS tube is coupled with a power supply voltage, and the other end of the first MOS tube is coupled with the base electrode of the IGBT; the grid electrode of the second MOS tube is coupled with the second output end of the signal conditioning circuit, one end of the second MOS tube is grounded, and the other end of the second MOS tube is coupled with the base electrode of the IGBT.

Optionally, when the second control voltage is at a high level, the first transistor is turned off, the third resistor and the fourth resistor divide a voltage to enable a voltage difference to exist between a base of the second transistor and ground, the second transistor is turned on, an anode of the first diode is grounded through the second transistor, the first diode is broken down, a cathode voltage of the first diode controls the first MOS transistor to be turned on, and the power supply voltage provides a base voltage for the IGBT through the first MOS transistor to control the IGBT to be turned on; when the second control voltage is at a low level, the second transistor is turned off, a voltage difference exists between the base of the first transistor and the power supply voltage due to the voltage division of the first resistor and the second resistor, the first transistor is turned on, the cathode of the second diode is connected to the power supply voltage through the first transistor, the second diode is broken down, the anode voltage of the second diode controls the second MOS transistor to be turned on, and the base of the IGBT releases charges to the ground through the second MOS transistor to control the IGBT to be turned off.

Optionally, the third control voltage is configured by configuring regulated voltage values of the first diode and the second diode.

Optionally, the IGBT driving circuit further includes: and the monitoring circuit is coupled with the collector electrode of the IGBT, is suitable for detecting the voltage between the collector electrode and the emitter electrode of the IGBT, and takes protection operation when the IGBT is detected to be abnormal.

Optionally, the monitoring circuit includes: a fifth diode, a cathode of which is coupled to a collector of the IGBT via a load resistor; a third transistor, wherein the base of the third transistor is coupled to the anode of the fifth diode, and one terminal of the third transistor is grounded; a tenth resistor, a first end of which is coupled to the other end of the third transistor; a cathode of the sixth diode is coupled to the second end of the tenth resistor; and the first end of the eleventh resistor is coupled with the anode of the sixth diode, and the second end of the eleventh resistor is connected with a power supply voltage.

Optionally, when the IGBT is out of saturation, the voltage of the base emitter of the IGBT is higher than the turn-on voltage of the IGBT, and the voltage between the collector and the emitter of the IGBT increases, so that the potential of the cathode of the fifth diode rises, the fifth diode is broken down, the third transistor is turned on, and the first end of the tenth resistor outputs a low level to indicate that the circuit operating state is abnormal; through the voltage division of the tenth resistor and the eleventh resistor, the potential of the second control voltage is at a low level, the base of the IGBT releases charges to the ground, and the IGBT is turned off.

Compared with the prior art, the technical scheme of the embodiment of the invention has the following beneficial effects:

the IGBT driving circuit comprises a signal isolation circuit, an amplifying circuit and a signal conditioning circuit: the signal isolation circuit is suitable for being externally connected with a control voltage and isolating the control voltage to obtain a first control voltage; the amplifying circuit is suitable for amplifying the first control voltage, and the output end of the amplifying circuit outputs a second control voltage; the signal conditioning circuit is suitable for generating a third control voltage according to the second control voltage so as to control the IGBT to be turned on and off, and the third control voltage is configurable. According to the technical scheme, the signal conditioning circuit is arranged, so that the IGBT driving circuit can provide configurable third control voltage for the IGBT to control the on and off of the IGBT, the IGBT driving circuit can drive the IGBTs with different power levels, and the application range of the IGBT driving circuit is expanded.

Further, the switch control circuit may include a first MOS transistor and a second MOS transistor to control on and off of the IGBT, respectively. Because the internal resistance is very low when the MOS tube is switched on, an ideal charge release path can be provided for the IGBT, so that the requirement of rapidly releasing charges when the IGBT is switched off is met, and the driving performance of the IGBT driving circuit is improved.

Drawings

FIG. 1 is a structural diagram of an IGBT driving circuit according to an embodiment of the invention;

FIG. 2 is a block diagram of another IGBT drive circuit according to an embodiment of the present invention;

FIG. 3 is a block diagram of another IGBT driving circuit according to the embodiment of the present invention;

fig. 4 is a structural diagram of an IGBT driving circuit according to still another embodiment of the present invention.

Detailed Description

As described in the background, the non-variability of the driving voltage output by the IGBT driving circuits in the prior art leads to limitations in the application of these circuits. In the application occasions with larger interference, such as vehicle starting or emergency braking, the IGBT may not be reliably turned off and mistakenly turned on, so that the motor is not normally operated to cause accidents; when the IGBT modules with different power levels are used, the type-selection driving system is often required to be redesigned, and the cost is increased.

The IGBT driving circuit with excellent performance should have the following features: firstly, the device has a good isolation function and has small time delay to signals; secondly, the device can provide forward and reverse base voltage with certain amplitude and has enough driving capability; in addition, the circuit structure should be as simple as possible, and small in size, so as to save the installation space.

According to the technical scheme, the signal conditioning circuit is arranged, so that the IGBT driving circuit can provide configurable third control voltage for the IGBT to control the on and off of the IGBT, and strong anti-interference performance is realized by providing enough positive and negative bias voltage, so that the IGBT driving circuit can drive the IGBTs with different power levels, and the application range of the IGBT driving circuit is expanded. Meanwhile, the IGBT driving circuit is small in size and easy to integrate; the IGBT driving circuit also has good strong and weak electric isolation performance.

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.

Fig. 1 is a structural diagram of an IGBT driving circuit according to an embodiment of the present invention.

As shown in fig. 1, the IGBT driver circuit may include a signal isolation circuit 101, an amplification circuit 102, and a signal conditioning circuit 103.

The signal isolation circuit 101 is adapted to externally connect to the control voltage Vin and isolate the control voltage Vin to obtain the first control voltage Vout 1.

The amplifying circuit 102 is adapted to amplify the first control voltage, and an output terminal thereof outputs a second control voltage Vout 2.

The signal conditioning circuit 103 is adapted to generate a third control voltage Vout3 for controlling the turn-on and turn-off of the IGBT according to the second control voltage Vout2, the third control voltage Vout3 being configurable.

In specific implementation, the signal isolation circuit 101 can realize access of the control voltage Vin, and simultaneously realize isolation of an external control circuit (i.e., a front-stage circuit) and the IGBT driving circuit, so as to avoid signal interference. Specifically, the signal isolation circuit 101 may be a photo coupler. The input end of the photoelectric coupler is connected with a control pulse signal from an external control circuit, and the output voltage signal can control the on-off of the IGBT through a subsequent circuit.

In a specific implementation, in order to ensure the driving capability, the first control voltage Vout1 output by the signal isolation circuit 101 may be amplified, and this operation may be implemented by the amplifying circuit 102.

In specific implementation, the signal conditioning circuit 103 generates the third control voltage Vout3 to control the turn-on and turn-off of the IGBT, and the third control voltage Vout3 generated by the signal conditioning circuit 103 can be configured, so that the IGBT driving circuit can be adapted to IGBTs in different power ranges by configuring the third control voltage Vout3 generated by the signal conditioning circuit 103, and the application range of the IGBT driving circuit is expanded.

Fig. 2 is a structural diagram of another IGBT driving circuit according to an embodiment of the present invention.

As shown in fig. 2, the signal isolation circuit 101 is a photo coupler U1. The amplifying circuit 102 is a transistor VT 3. The input end of the photoelectric coupler U1 is connected to the control voltage of the preceding stage circuit, and the output end of the photoelectric coupler U1 is coupled to the base of the transistor VT3 to control the on-off of the transistor VT 3. For example, input PIN 1 and input PIN 2 of the photocoupler U1 are connected to the control voltage of the previous stage circuit, and output PIN 3 is coupled to the base of the transistor VT 3. Transistor VT3 may be used for primary power amplification of the base pulse needed to control the IGBT turning on and off.

Specifically, the base of the transistor VT3 is connected to the supply voltage (i.e., supply voltage) VCC through a resistor, and the emitter of the transistor VT3 is grounded. When the transistor VT3 is turned on by the first control voltage output by the photocoupler U1, the collector potential of the transistor VT3 is 0, the second control voltage is low, and the potential at the point a is 0; when the transistor VT3 is turned off by the first control voltage output from the photocoupler U1, the collector potential of the transistor VT3 is the power supply voltage VCC, the second control voltage is high level, and the potential at the point a is the power supply voltage VCC.

In this embodiment, the signal conditioning circuit 103 may include a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a first transistor VT1, and a second transistor VT 2.

The first end of the first resistor R1 is connected with a power supply voltage; a second resistor R2, a third resistor R3 and a fourth resistor R4 are connected in series in sequence, a first end of the second resistor R2 is coupled to a second end of the first resistor R1, and a second end of the fourth resistor R4 is grounded; a first transistor VT1 having a base coupled to the second terminal of the first resistor R1, an emitter connected to the power supply voltage VCC, and a collector as an output terminal of the signal conditioning circuit 103 for outputting the third control voltage; a second transistor VT2, the base of which is coupled to the second terminal of the third resistor R3, the collector of which is coupled to the other terminal of the first transistor, and the emitter of which is grounded. Specifically, the output terminal of the signal conditioning circuit 103 may correspond to point B in the circuit shown in fig. 2.

In a specific implementation, the output terminal of the voltage conditioning circuit 103 may provide a suitable voltage for turning on and off the IGBT. Specifically, when the potential at the point a is at a low level (for example, the voltage value is 0), the second transistor VT2 is turned off, the voltage division between the first resistor R1 and the second resistor R2 causes a voltage difference between the base of the first transistor VT1 and the power supply voltage VCC, the first transistor VT1 is turned on, and the power supply voltage VCC provides a base voltage for the IGBT via the first transistor VT1, so as to control the IGBT to be turned on. When the potential of the point a is the power supply voltage VCC, the first transistor VT1 is turned off, the third resistor R3 and the fourth resistor R4 divide the voltage to make a voltage difference exist between the base of the second transistor VT2 and the ground, the second transistor VT2 is turned on, the base of the IGBT releases charges to the ground through the second transistor VT2, and the IGBT is controlled to be turned off.

In this embodiment, when the potential at the point a is 0, the potential at the output end (i.e., the point B) of the voltage conditioning circuit 103 is the power supply voltage VCC; when the potential at the point a is the power supply voltage VCC, the potential is 0. That is, the turn-on voltages can be provided for the IGBTs of different powers by configuring the supply voltage VCC.

Those skilled in the art will appreciate that the types of the transistor VT3, the first transistor VT1, and the second transistor VT2 (e.g., PNP transistor and NPN transistor) can be selected and configured according to the actual application environment; the transistor VT3, the first transistor VT1 and the second transistor VT2 may also be replaced by switching tubes for any practical switching function.

Since the transistors (the first transistor VT1 and the second transistor VT2) allow a smaller current, the voltage conditioning circuit 103 may be further improved on the basis of the IGBT driving circuit shown in fig. 2 in order to further improve the driving capability of the IGBT driving circuit.

Referring to fig. 3, fig. 3 is a structural diagram of another IGBT driving circuit according to an embodiment of the invention.

Referring to fig. 2, the signal conditioning circuit 103 of the present embodiment may include a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a first transistor VT1, and a second transistor VT 2; the signal conditioning circuit 103 may further include a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, a first diode Z1, and a second diode Z2.

A first end of the fifth resistor R5 is coupled to the power supply voltage VCC; a first end of the sixth resistor R6 is coupled to the second end of the fifth resistor R5, and a second end thereof is grounded; a first end of the seventh resistor R7 is connected to the power supply voltage VCC; the cathode of the first diode Z1 is coupled to the second end of the seventh resistor R7 and serves as the first output end of the signal conditioning circuit 103; the cathode of the second diode Z2 is coupled to the anode of the first diode Z1, and the anode thereof is coupled to the second terminal of the fifth resistor R5 and serves as the second output terminal of the signal conditioning circuit 103.

In this embodiment, the IGBT driving circuit further includes a switch control circuit 301. The switch control circuit 301 is adapted to be coupled to the first output terminal and the second output terminal of the signal conditioning circuit 103, and respectively generate a fourth control voltage and a fifth control voltage according to the voltages output by the first output terminal and the second output terminal of the signal conditioning circuit 103, so as to respectively control the on and off of the IGBT. Specifically, the first output terminal and the second output terminal of the signal conditioning circuit 103 correspond to the points C and D, respectively, in the circuit shown in fig. 3.

In a specific implementation, the switch control circuit 301 may include a first MOS transistor Q1 and a second MOS transistor Q2; a gate of the first MOS transistor Q1 is coupled to the first output terminal of the signal conditioning circuit 103, one end of the first MOS transistor Q1 is coupled to the supply voltage VCC, and the other end of the first MOS transistor Q1 is coupled to a base of the IGBT; the gate of the second MOS transistor Q2 is coupled to the second output terminal of the signal conditioning circuit 103, one end of the second MOS transistor Q2 is grounded, and the other end of the second MOS transistor Q2 is coupled to the base of the IGBT.

Specifically, when the second control voltage output by the amplifying circuit 102 is at a high level, that is, the potential at the point a is at a high level, the first transistor VT1 is turned off, the third resistor R3 and the fourth resistor R4 divide the voltage to make a voltage difference exist between the base of the second transistor VT2 and the ground, that is, the voltage at the point F makes the second transistor VT2 be turned on, the anode of the first diode Z1 is grounded via the second transistor VT2, the first diode Z1 is broken down, the voltage at the point C is the regulated voltage Vz1 of the first diode Z1, the voltage at the point C controls the first MOS transistor Q1 to be turned on, and the power supply voltage VCC provides the base voltage for the IGBT via the first MOS transistor Q1 to control the IGBT to be turned on; when the potential of the point a is at a low level, the second transistor VT2 is turned off, the voltage division of the first resistor R1 and the second resistor R2 makes a voltage difference between the base of the first transistor VT1 and the power supply voltage VCC, that is, the voltage of the point E makes the first transistor VT1 be turned on, the cathode of the second diode Z2 is connected to the power supply voltage VCC through the first transistor VT1, the second diode Z2 is broken down, the voltage of the point D is the difference VCC-Vz2 between the power supply voltage and the regulated voltage value of the second diode Z2, the voltage of the point D controls the conduction of the second MOS transistor Q2, and the base of the IGBT releases charges to the ground through the second MOS transistor, thereby controlling the turn-off of the IGBT.

In this embodiment, when the potential of the point a is at a high level, the first output terminal of the voltage conditioning circuit 103, that is, the point C, has a voltage equal to the regulated voltage Vz1 of the first diode Z1; when the voltage at the point a is low, the second output terminal of the voltage conditioning circuit 103, i.e., the point D, has a voltage VCC-Vz2 which is the difference between the power voltage and the regulated voltage of the second diode Z2. That is, the conduction of the first MOS transistor Q1 and the second MOS transistor Q2 can be controlled by configuring the power supply voltage VCC, the regulated voltage value of the first diode Z1, and the regulated voltage value of the second diode Z2, so as to provide conduction voltages for IGBTs of different powers.

It should be understood by those skilled in the art that the first MOS transistor Q1 shown in fig. 3 is a PMOS transistor, and the second MOS transistor Q2 is an NMOS transistor; in a specific application scenario, the first MOS transistor Q1 and the second MOS transistor Q2 may further cooperate with the signal conditioning circuit to select different combinations, for example, the first MOS transistor Q1 is an NMOS transistor, and the second MOS transistor Q2 is a PMOS transistor, which is not limited in this embodiment of the present invention.

Furthermore, the models of the first MOS transistor Q1 and the second MOS transistor Q2 can be selected to adapt to IGBTs in different power ranges. Furthermore, the appropriate regulated voltage values of the first diode Z1 and the second diode Z2 can be selected to control the on and off of MOS transistors with different driving powers. Furthermore, the on-off voltage value of the MOS tube is generally required to be minus dozens of volts to plus dozens of volts; if the proper voltage stabilizing values of the first diode Z1 and the second diode Z2 are selected, the signal conditioning circuit can provide driving voltage of about plus or minus 10V, so that the on-off requirements of most MOS (metal oxide semiconductor) tubes can be met, the IGBT driving circuit can drive IGBTs with different power levels, and the application range of the IGBT driving circuit is expanded.

Since the turn-on speed of the transistor is slower, the IGBT driving circuit shown in fig. 2 has a certain limitation on the switching speed of the IGBT, so in an application scenario where the requirement on the switching speed of the IGBT is not high, the IGBT driving circuit shown in fig. 2 may be used. In the IGBT driving circuit shown in fig. 3, the first MOS transistor Q1 and the second MOS transistor Q2 are used to control the on/off of the IGBT, and since the MOS transistors have high driving power and high switching speed, the performance of the IGBT driving circuit can be further improved.

For the IGBT drive circuit, a suitable base drive voltage needs to be supplied to the IGBT. The magnitude of the base forward driving voltage will have a large impact on the IGBT performance. When the forward driving voltage increases, the on-resistance of the IGBT decreases, and the conduction loss decreases. If the forward driving voltage is too large, the IGBT is easy to damage; if the forward driving voltage is too small, the IGBT is easy to exit from the saturated conduction region and enter the linear amplification region, and the IGBT is easy to overheat and damage. In addition, the IGBT driving circuit also needs to supply a sufficient driving current to the IGBT. Because a large parasitic capacitance exists between every two three poles of the IGBT, large charging and discharging currents exist during the rising and falling edges of the driving pulse voltage. In order to meet the dynamic requirements of on and off, a driving circuit of the IGBT is required to have certain peak current output capability, so that the IGBT cannot be damaged due to exiting from a saturated conducting area under the normal working and overload conditions. The IGBT driving circuits shown in the figures 2 and 3 in the embodiment of the invention can meet the requirements.

The specific implementation of the signal isolation circuit 101 (the photocoupler U1) and the amplification circuit 102 (the transistor VT3) in this embodiment can refer to the IGBT driving circuit shown in fig. 2, and will not be described herein again.

Referring to fig. 2 and 3 together, compared to the IGBT driving circuit shown in fig. 3, the signal conditioning circuit 103 further includes a third diode a1, a first capacitor C1, an eighth resistor R8, a ninth resistor R9, a second capacitor C2, and a fourth diode a2 to suppress a surge existing in the signal conditioning circuit 103 to protect the signal conditioning circuit 103.

The cathode of the third diode A1 is connected to the power supply voltage VCC; a first end of a first capacitor C1 is coupled to the anode of the third diode A1; the eighth resistor R8 has a first terminal coupled to the second terminal of the first capacitor C1, and a second terminal coupled to the output terminal of the amplifying circuit 102; a first end of the ninth resistor R9 is coupled to the output end of the amplifying circuit 102; a first end of a second capacitor C2 is coupled to a second end of the ninth resistor R9; the cathode of the fourth diode a2 is coupled to the second terminal of the second capacitor C2, and the anode thereof is grounded.

Specifically, the ninth resistor R9 and the second capacitor C2 provide a base current path for the second transistor VT2 at the moment that the transistor VT3 is turned off, so as to avoid affecting the operating state of the IGBT; similarly, the eighth resistor R8 and the first capacitor C1 provide a base current path for the first transistor VT1 at the instant when the transistor VT3 is turned on. When a negative voltage (e.g., a transient surge, etc.) occurs between the third resistor R3 and the fourth resistor R4, i.e., at point F, the fourth diode a2 is turned on, so that the voltage of the emitter of the second transistor VT2 can be clamped to-0.7V, thereby preventing the negative voltage from being too high to break down the second transistor VT2 in the reverse direction. Similarly, when a negative voltage (e.g., a transient surge, etc.) occurs between the first resistor R1 and the second resistor R2, i.e., at point E, the third diode a1 is turned on, so that the voltage of the emitter of the first transistor VT1 can be clamped to-0.7V, thereby preventing the negative voltage from being too high to break down the first transistor VT1 in the reverse direction.

The IGBT driving circuit shown in fig. 4 further includes a monitoring circuit coupled to the collector of the IGBT, adapted to detect a voltage between the collector and the emitter of the IGBT, and to take a protection operation when an abnormality of the IGBT is detected. The protection operation may be any suitable operation that is preset.

In a specific implementation, the monitoring circuit may include: a fifth diode Z3, a third transistor VT4, a tenth resistor R10, a sixth diode A3, and an eleventh resistor R11. The transistor VT3 is coupled to the power supply voltage VCC via an eleventh resistor R11.

Wherein, the cathode of the fifth diode Z3 is coupled to the collector of the IGBT via a load resistor (not shown); the base of the third transistor VT4 is coupled to the anode of the fifth diode Z3, and one end of the third transistor VT4 is grounded; a first end of a tenth resistor R10 is coupled to the other end of the third transistor VT 4; a cathode of the sixth diode a3 is coupled to the second terminal of the tenth resistor R10; a first end of the eleventh resistor R11 is coupled to the anode of the sixth diode A3, and a second end thereof is connected to the power supply voltage VCC.

Specifically, when the IGBT is normally turned on, the IGBT operates in a saturation state, the voltage drop between the collector and the emitter is small, the voltage of the emitter of the IGBT is stable, and the potential of the collector of the IGBT is low. When the IGBT is out of saturation, the voltage between the base and the emitter of the IGBT is higher than the turn-on voltage of the IGBT, the voltage between the collector and the emitter of the IGBT increases, so the collector voltage of the IGBT increases, the cathode of the fifth diode Z3 is coupled to the collector of the IGBT, which causes the potential of the cathode of the fifth diode Z3 to increase, the fifth diode Z3 is broken down, the third transistor VT4 is turned on, the first end of the tenth resistor R10 serves as an output PIN P5, and a low level is output to indicate that the circuit operation state of the IGBT driving circuit is abnormal; the potential at the point A is low through the voltage division of the tenth resistor R10 and the eleventh resistor R11, the base of the IGBT discharges the charges to the ground, and the IGBT is turned off.

Further, the output PIN P5 may indicate the operating state of the IGBT driving circuit, and if the IGBT is normally turned on and off, the output PIN P5 always outputs a high level; if the IGBT is abnormally operated and exits the saturation state, the third transistor VT4 is broken down, and the output PIN P5 outputs a rectangular wave.

Specifically, when the IGBT is normally turned on and off, the circuit formed by the third capacitor C3, the fourth capacitor C4 and the thirteenth resistor R13 may prevent the cathode potential of the fifth diode Z3 from rising, so as to prevent the fifth diode Z3 from being broken down. Therefore, in the monitoring circuit, the tenth resistor R10 and the eleventh resistor R11 are matched in resistance value, so that the potential at the point a at this time can be kept at a lower value, the first transistor VT1 is turned on by the partial voltage of the first resistor R1 and the second resistor R2, the first transistor VT2 is turned off by the partial voltage of the third resistor R3 and the fourth resistor R4, the second diode Z2 is broken down, the first MOS transistor Q1 is turned off, the second MOS transistor Q2 is turned on, the base charge of the IGBT is rapidly released through the second MOS transistor Q2, the IGBT is turned off, and the IGBT is prevented from being damaged due to the fact that a large noise is generated by a collector when the IGBT exits a saturation state.

Further, when the tenth resistor R10 and the eleventh resistor R11 are matched, the resistance of the tenth resistor R10 is smaller; the on-state current of the third transistor VT4 is usually several tens of milliamperes, so as to avoid damage to the third transistor VT4 due to excessive current, while the tenth resistor R10 and the eleventh resistor R11 are matched in resistance value, the twelfth resistor R12 can be used for shunting, so as to realize current limiting of the third transistor VT 4.

It should be noted that "low level (or low potential)" and "high level (or high potential)" are relative concepts, and specific ranges of the two are not limited as long as the voltage value of the low level is lower than that of the high level.

Although the present invention is disclosed above, the present invention is not limited thereto. Various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. An IGBT driving circuit characterized by comprising:

the signal isolation circuit is suitable for being externally connected with a control voltage and isolating the control voltage to obtain a first control voltage; the amplifying circuit is suitable for amplifying the first control voltage, and the output end of the amplifying circuit outputs a second control voltage;

the signal conditioning circuit is suitable for generating a third control voltage according to the second control voltage so as to control the IGBT to be switched on and off, and the third control voltage is configurable;

the signal conditioning circuit includes:

a first resistor, a first end of which is connected to a power supply voltage;

the first end of the second resistor is coupled with the second end of the first resistor, and the second end of the fourth resistor is grounded;

a first transistor, a base of which is coupled to the second end of the first resistor, one end of which is connected to the power voltage, and the other end of which is used as an output end of the signal conditioning circuit to output the third control voltage;

a base of the second transistor is coupled to the second end of the third resistor, one end of the second transistor is coupled to the other end of the first transistor, and the other end of the second transistor is grounded;

configuring the third control voltage by configuring the supply voltage;

the signal conditioning circuit further comprises:

a first end of the fifth resistor is coupled with the power supply voltage;

a sixth resistor, a first end of which is coupled to the second end of the fifth resistor, and a second end of which is grounded;

a seventh resistor having a first end connected to the power supply voltage;

a cathode of the first diode is coupled to the second end of the seventh resistor and serves as a first output end of the signal conditioning circuit;

a second diode, a cathode of which is coupled to the anode of the first diode, and an anode of which is coupled to the second end of the fifth resistor and serves as a second output end of the signal conditioning circuit;

the signal conditioning circuit further comprises:

a third diode having a cathode connected to the power supply voltage;

a first end of the first capacitor is coupled with the anode of the third diode;

a first end of the eighth resistor is coupled to the second end of the first capacitor, and a second end of the eighth resistor is coupled to the output end of the amplifying circuit;

a ninth resistor, a first end of which is coupled to the output end of the amplifying circuit;

a first end of the second capacitor is coupled to the second end of the ninth resistor;

and the cathode of the fourth diode is coupled with the second end of the second capacitor, and the anode of the fourth diode is grounded.

2. The IGBT drive circuit according to claim 1, further comprising:

and the switch control circuit is coupled with the first output end and the second output end of the signal conditioning circuit and is suitable for respectively generating a fourth control voltage and a fifth control voltage according to the voltages output by the first output end and the second output end of the signal conditioning circuit so as to respectively control the on-off of the IGBT.

3. The IGBT drive circuit according to claim 2, wherein the switch control circuit comprises a first MOS transistor and a second MOS transistor; the grid electrode of the first MOS tube is coupled with the first output end of the signal conditioning circuit, one end of the first MOS tube is coupled with a power supply voltage, and the other end of the first MOS tube is coupled with the base electrode of the IGBT; the grid electrode of the second MOS tube is coupled with the second output end of the signal conditioning circuit, one end of the second MOS tube is grounded, and the other end of the second MOS tube is coupled with the base electrode of the IGBT.

4. The IGBT driving circuit according to claim 3, wherein when the second control voltage is high level, the first transistor is turned off, the third resistor and the fourth resistor divide the voltage to make a voltage difference exist between the base of the second transistor and the ground, the second transistor is turned on, the anode of the first diode is grounded via the second transistor, the first diode is broken down, the cathode voltage of the first diode controls the first MOS transistor to be turned on, the power supply voltage provides the base voltage for the IGBT via the first MOS transistor, and the IGBT is controlled to be turned on; when the second control voltage is at a low level, the second transistor is turned off, a voltage difference exists between the base of the first transistor and the power supply voltage due to the voltage division of the first resistor and the second resistor, the first transistor is turned on, the cathode of the second diode is connected to the power supply voltage through the first transistor, the second diode is broken down, the anode voltage of the second diode controls the second MOS transistor to be turned on, and the base of the IGBT releases charges to the ground through the second MOS transistor to control the IGBT to be turned off.

5. The IGBT driver circuit of claim 1, wherein the third control voltage is configured by configuring regulated values of the first diode and the second diode.

6. The IGBT drive circuit according to claim 1, further comprising:

and the monitoring circuit is coupled with the collector electrode of the IGBT, is suitable for detecting the voltage between the collector electrode and the emitter electrode of the IGBT, and takes protection operation when the IGBT is detected to be abnormal.

7. The IGBT drive circuit of claim 6, wherein the monitoring circuit comprises: a fifth diode, a cathode of which is coupled to a collector of the IGBT via a load resistor;

a third transistor, wherein the base of the third transistor is coupled to the anode of the fifth diode, and one terminal of the third transistor is grounded;

a tenth resistor, a first end of which is coupled to the other end of the third transistor;

a cathode of the sixth diode is coupled to the second end of the tenth resistor;

and the first end of the eleventh resistor is coupled with the anode of the sixth diode, and the second end of the eleventh resistor is connected with a power supply voltage.

8. The IGBT driving circuit according to claim 7, wherein when the IGBT is out of saturation, the voltage between its base and emitter is higher than its on-voltage, the voltage between its collector and emitter increases, which causes the cathode voltage of the fifth diode to rise, the fifth diode is broken down, the third transistor is turned on, and the first end of the tenth resistor outputs a low level to indicate that the circuit operation state is abnormal; through the voltage division of the tenth resistor and the eleventh resistor, the potential of the second control voltage is at a low level, the base of the IGBT releases charges to the ground, and the IGBT is turned off.