CN112104346A

CN112104346A - IGBT high-voltage drive overcurrent and overvoltage protection circuit

Info

Publication number: CN112104346A
Application number: CN202010897016.2A
Authority: CN
Inventors: 马春光; 杜凌志; 熊佼佼; 周二建; 吕洪光; 罗勇
Original assignee: University of Electronic Science and Technology of China
Current assignee: University of Electronic Science and Technology of China
Priority date: 2020-08-31
Filing date: 2020-08-31
Publication date: 2020-12-18
Anticipated expiration: 2040-08-31
Also published as: CN112104346B

Abstract

The invention discloses a high-voltage driving overcurrent and overvoltage protection circuit for an IGBT (insulated gate bipolar transistor), and belongs to the technical field of electronic circuits. The circuit comprises an IGBT, an IGBT driving module, a feedback controller, a current detection module and a voltage detection module. According to the invention, the current detection module is adopted to prevent the over-current and short circuit of the IGBT, especially when the large current caused by the short circuit flows, the self-turn-off design can rapidly reduce the pressure difference between the grid electrode and the emitter electrode of the IGBT, and prevent the large current from passing through the IGBT for too long time. The voltage detection module can prevent the overvoltage of the IGBT by adopting the clamping circuit, and can input feedback voltage and current to the grid electrode of the IGBT after the TVS tube is broken down, so that the IGBT can be rapidly turned on, and the overvoltage protection can be realized in a short time. The invention has simple structure, and can adjust the resistance of the sampling resistor, the divider resistor or the voltage-stabilizing tube according to the requirement to meet different application requirements.

Description

IGBT high-voltage drive overcurrent and overvoltage protection circuit

Technical Field

The invention belongs to the technical field of electronic circuits, and relates to a high-voltage driving overcurrent and overvoltage protection circuit for an IGBT.

Background

An Insulated Gate Bipolar Transistor (IGBT) is a composite fully-controlled voltage-driven power semiconductor switch device consisting of a Bipolar Junction Transistor (BJT) and an insulated gate field effect transistor (MOS). The device integrates the advantages of two switching devices, has the advantages of high input impedance of an MOS (metal oxide semiconductor) tube, high working speed and easiness in driving, and also has the advantages of saturation voltage reduction of a BJT (bipolar junction transistor) tube, large current capacity, high voltage resistance and the like, so that the device is widely applied to the fields of high-frequency electric welding machines, alternating current motors, frequency converters, switching power supplies, traction transmission and the like.

However, since the IGBT is often used in high-voltage and high-power applications, the operating environment is relatively harsh, and the driving voltage is high, the protection of the IGBT is particularly important, and the protection time needs to be controlled in a safe operating area of the IGBT to prevent the IGBT from being damaged. At present, common overcurrent protection circuits feed results back to a controller after detection, and turn off the IGBT after overcurrent judgment, but the turn-off time of the IGBT is often prolonged, so that high thermal resistance is possibly generated for the IGBT, and adverse effects are generated on an IGBT module. The common overvoltage protection circuit is composed of a TVS tube, a common fast recovery diode and a resistor, when overvoltage at two ends of the IGBT reaches a certain degree, the TVS tube breaks down to charge a grid electrode, so that the IGBT can keep certain opening, the IGBT is prevented from being damaged, meanwhile, a turn-off signal is output to a driving chip through feedback, the IGBT is turned off, but the TVS tube maintains the broken state at the moment, if the turn-off time of the IGBT is too long, the TVS tube can be damaged due to thermal breakdown, and then the two ends of the IGBT are damaged due to overvoltage. Therefore, it is necessary to overcome these drawbacks by improving the over-current and over-voltage protection circuit of the IGBT.

Disclosure of Invention

In view of the defects in the prior art, the invention aims to provide an overcurrent and overvoltage protection circuit for high-voltage driving of an IGBT, which solves the problem that the response speed of a high-voltage driving circuit to an overcurrent and overvoltage state is too low, and realizes quick protection of the IGBT under a high-voltage condition.

In order to achieve the purpose, the invention adopts the following technical scheme to realize the following steps:

the circuit comprises an IGBT, an IGBT driving module, a feedback controller, a current detection module and a voltage detection module.

The IGBT comprises a grid electrode, a collector electrode and an emitter electrode.

The IGBT driving module is used for providing voltage and current for the IGBT and controlling the on and off of the IGBT according to the received turn-on signal or turn-off signal.

The current detection module is used for detecting the passing current of the IGBT, converting the current sampling signal into a voltage signal and sending the voltage signal to the feedback controller.

And the voltage detection module is used for detecting the voltages at two ends of the IGBT and sending the voltage sampling signal to the feedback controller.

And the feedback controller outputs a switching-on signal or a switching-off signal to the IGBT driving module according to the current sampling signal and the voltage sampling signal.

The IGBT current detection device is characterized in that the current detection module samples the IGBT current and transmits the IGBT current to the feedback controller for judgment when the IGBT normally works. When the current of the IGBT does not exceed the overcurrent threshold, the feedback controller outputs a switching-on signal; when the IGBT is overcurrent, the feedback controller outputs a turn-off signal; when the IGBT is in short circuit, the grid voltage is accelerated to discharge through the voltage regulator tube, so that the voltage between the grid and the emitter is rapidly reduced, the IGBT is automatically turned off, and the phenomenon that the IGBT passes a large current for too long time is prevented.

Further, after the IGBT is turned off by mistake, the voltage detection module detects that the voltages at two ends of the IGBT exceed a voltage threshold value, the voltage detection module transmits a sampling voltage signal to the feedback controller, and the feedback controller outputs a turn-on signal to turn on the IGBT again; meanwhile, the voltage detection module feeds back voltage and current to the IGBT grid to accelerate the turn-on of the IGBT.

The invention has the following beneficial effects: the invention adopts the current detection module to prevent the over-current and short circuit of the IGBT, adopts the resistor to directly sample the current, and can quickly reduce the pressure difference between the grid G and the emitter E of the IGBT. Especially when large current caused by short circuit flows, the self-turn-off design can rapidly reduce the voltage difference between the gate and the emitter of the IGBT, and prevent the large current from flowing through the IGBT for too long time. The voltage detection module can prevent the overvoltage of the IGBT by adopting the clamping circuit, and can input feedback voltage and current to the grid electrode of the IGBT after the TVS tube is broken down, so that the IGBT can be rapidly turned on, and the overvoltage protection can be realized in a short time. The voltage detection module and the current detection module use the same feedback controller to judge the sampling signal, so that the circuit structure is simplified, and the judgment accuracy of the controller is improved; meanwhile, the invention has simple structure, and can adjust the resistance values of the sampling resistor, the divider resistor or the voltage-stabilizing tube according to the requirements to meet different application requirements.

Drawings

Fig. 1 is a block diagram of an IGBT protection circuit in an embodiment of the invention;

FIG. 2 is a self-shutdown circuit diagram in an embodiment of the invention;

FIG. 3 is a circuit diagram of a current sensing module in an embodiment of the invention;

fig. 4 is a circuit diagram of a voltage detection module in an embodiment of the invention.

Detailed Description

In order to more clearly illustrate the technical solution of the present invention, the present invention is described in detail below with reference to the embodiments and the accompanying drawings.

Fig. 1 is a block diagram of an IGBT protection circuit in an embodiment of the present invention, where the embodiment includes an IGBT driving module, a current detection module, a voltage detection module, and a feedback controller. The current detection module samples the current of the IGBT, converts a current sampling signal into a voltage signal and transmits the voltage signal to a port 1 of the feedback controller, when the IGBT is in overcurrent, the feedback controller outputs a turn-off signal to the IGBT driving module, the IGBT driving module outputs a turn-off signal, and the IGBT is turned off; the voltage detection module feeds back the acquired voltage sampling signal to the feedback controller, when the two ends of the IGBT are overvoltage, the feedback controller outputs a switching-on signal to the IGBT driving module, the IGBT is turned on again by the driving module, and meanwhile, the voltage detection module feeds back voltage and current to the grid electrode of the IGBT to accelerate the switching-on of the IGBT.

Fig. 2 is a self-turn-off circuit diagram of the current detection module in the embodiment of the present invention, which includes a voltage regulator tube D7, a sampling resistor R3, a TVS tube D4, and a D2, wherein the anode of the voltage regulator tube D7 is grounded, and the cathode is connected to an IGBT gate G; one end of the sampling resistor R3 and one end of the TVS tube D4 are connected with the emitter E, and the other end is grounded; the TVS tube D2 has one end connected to the gate G and the other end connected to the emitter E. When the IGBT has excessive current (short circuit), the voltage across the sampling resistor R3 rises rapidly and is clamped by the TVS transistor D4. Meanwhile, under the action of the TVS tube D2, the rise of the voltage across the sampling resistor R3 causes the rise of the gate voltage, and when the gate voltage exceeds the threshold of the voltage regulator tube D7, the gate voltage is discharged through the D7 and clamped. At this time, the voltage between G-E is rapidly reduced, the current which can be passed by the IGBT is rapidly reduced, and the IGBT is prevented from being damaged by overcurrent.

Fig. 3 is a circuit diagram of a current detection module provided in an embodiment of the present invention. The current detection module comprises a sampling resistor R3, a certain voltage is generated at two ends of the resistor R3 according to the value of a flowing current, and the TVS tube D4 limits the values at two ends of the sampling resistor R3 within a certain voltage range (or can be replaced by a voltage stabilizing tube); meanwhile, the current detection module further comprises a diode D3 for unidirectionally transmitting a voltage signal obtained by sampling the current signal to the port of the controller 1; the resistors R5 and R6 are used for dividing voltage signals, and limit the overcurrent threshold of sampling current signals together with the voltage regulator tube D5, and the capacitors C2, C3 and C4 delay the rising time of the converted voltage signals, so that the voltage of the port of the controller 1 is prevented from rising due to the instant fluctuation of current, the controller outputs a turn-off signal, and the IGBT is turned off mistakenly.

Fig. 4 is a circuit diagram of a voltage detection module provided in the embodiment of the present invention. The voltage detection module comprises voltage-sharing resistors R7, R8, R9 and R10, a clamping TVS tube D8, D9, D10 and D11, when the voltage of an IGBT collector C does not exceed the breakdown voltage of the TVS tube, the voltage is divided through the voltage-sharing resistors, only a small current passes through the voltage-sharing circuits, and no voltage can be seen at two ends of the sampling resistor R13. The voltage detection module also comprises a sampling resistor R13, when the voltage between the collector C and the ground exceeds the limit voltage of the TVS tube, the TVS tube (D8-D11) is broken down, and larger current can pass, and the voltage across the sampling resistor R13 rises. Meanwhile, after the voltages at the two ends of the voltage dividing resistor R12 and the sampling resistor R13 are increased, the voltage and the current are fed back to the grid through the resistor R14 and the diode D12, so that the IGBT driving module is helped to reopen the IGBT, and the voltage increase speed at the two ends of the IGBT is reduced. The sampled voltage signal is divided by resistors R15, R16 and R6, the voltage is transmitted to the ports of the controllers 1 and 2, and when the voltages of the ports of the controllers 1 and 2 reach the voltage threshold, the controllers output the turn-on signal again to turn on the IGBTs again. The capacitor C5 limits the rise rate of the sampled voltage signal, and the capacitors C4 and C6 are used to distinguish the voltage fall rates of the ports of the controllers 1 and 2.

The embodiment of the invention also improves the IGBT gate drive resistance, and when the IGBT is charged by the drive chip, the IGBT is driven by the diode D1 and the resistor R1; when the IGBT discharges, it discharges through resistor R2. The invention has simple actual circuit and few used devices, obviously improves the on-off speed of the grid, and can carry out sectional design according to the actual driving requirement.

In summary, according to the IGBT high-voltage driving overcurrent and overvoltage protection circuit provided by the invention, through the design of the self-shutdown circuit, the voltage regulator tube D7 can ensure that the IGBT can be effectively protected when the current lifting speed is too high and even short circuit occurs. Meanwhile, the current threshold can be changed by selecting the values of the sampling resistor and the divider resistor in the current detection module according to different circuit requirements, and the method is simple to operate and convenient to calculate. The problem of IGBT overcurrent and overvoltage under the high-voltage condition is solved, the reaction speed of the protection circuit is improved, the overcurrent and overvoltage feedback protection time of the IGBT is shorter, the IGBT can be effectively protected, and the reliability of the circuit is improved.

Claims

1. An IGBT high-voltage driving overcurrent and overvoltage protection circuit comprises an IGBT, an IGBT driving module, a feedback controller, a current detection module and a voltage detection module;

the IGBT comprises a grid electrode, a collector electrode and an emitter electrode;

the IGBT driving module is used for providing voltage and current for the IGBT and controlling the on and off of the IGBT according to the received turn-on signal or turn-off signal;

the current detection module is used for detecting the passing current of the IGBT, converting a current sampling signal into a voltage signal and sending the voltage signal to the feedback controller;

the voltage detection module is used for detecting the voltages at two ends of the IGBT and sending a voltage sampling signal to the feedback controller;

the feedback controller outputs a switching-on signal or a switching-off signal to the IGBT driving module according to the current sampling signal and the voltage sampling signal;

the IGBT current detection device is characterized in that when the IGBT works, the sampling resistor samples the IGBT current and transmits the IGBT current to the feedback controller for judgment; when the current of the IGBT does not exceed the overcurrent threshold, the feedback controller outputs a switching-on signal; when the current of the IGBT exceeds an overcurrent threshold value, the feedback controller outputs a turn-off signal; when the IGBT is in short circuit, the grid voltage is accelerated to discharge through the voltage-stabilizing tube, and the IGBT is automatically turned off.

2. The IGBT high-voltage driving overcurrent and overvoltage protection circuit as claimed in claim 1, wherein after the IGBT is turned off by mistake, the voltage detection module detects that the voltage at two ends of the IGBT exceeds a voltage threshold value, the voltage detection module transmits a sampling voltage signal to the feedback controller, and the feedback controller outputs a turn-on signal to turn on the IGBT again; meanwhile, the voltage detection module feeds back voltage and current to the IGBT grid to accelerate the turn-on of the IGBT.