CN109375087B - Protection circuit and method for detecting IGBT short-circuit fault at high speed - Google Patents

Protection circuit and method for detecting IGBT short-circuit fault at high speed Download PDF

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CN109375087B
CN109375087B CN201811184831.3A CN201811184831A CN109375087B CN 109375087 B CN109375087 B CN 109375087B CN 201811184831 A CN201811184831 A CN 201811184831A CN 109375087 B CN109375087 B CN 109375087B
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circuit
short
igbt
gate
detection
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CN109375087A (en
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席伟
刘忠超
张雨
张永浩
徐磊
廖良闯
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Lianyungang Jierui Electronics Co Ltd
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Lianyungang Jierui Electronics Co Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/26—Testing of individual semiconductor devices
    • G01R31/2607—Circuits therefor
    • G01R31/2608—Circuits therefor for testing bipolar transistors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/26—Testing of individual semiconductor devices
    • G01R31/2601—Apparatus or methods therefor
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections

Abstract

The invention relates to a protection circuit capable of detecting IGBT short-circuit fault at high speed, which comprises a detection control circuit, an HSF short-circuit detection circuit and an FUL short circuit detection circuit, OR gate logic circuit, gate drive circuit, soft turn-off circuit and gate resistor RG. The invention also discloses a method for protecting the IGBT short-circuit fault. The invention respectively detects two short circuit types of hard switch short circuit fault and on-load short circuit fault, provides a corresponding detection circuit, and is provided with a detection control circuit to control the working state of the short circuit detection circuit; the soft turn-off circuit performs short-circuit turn-off processing on the IGBT and locks an output signal of the driving circuit. The invention is to the grid voltage VGEAnd a driving voltage VGGThe detection is carried out, the detection circuit is simple, the short-circuit detection time is short, the short-circuit fault can be quickly and reliably processed, and the power device is effectively protected.

Description

Protection circuit and method for detecting IGBT short-circuit fault at high speed
Technical Field
The invention belongs to the field of power switch device drive protection, and particularly relates to a short-circuit protection method and a short-circuit protection circuit which adopt an IGBT as a power switch device.
Background
Insulated Gate Bipolar Transistor (IGBT) has the advantages of reduced on-state voltage and large current capacity, and has the advantages of high input impedance, fast response speed and simple control, so that it has been developed rapidly since the advent and is widely used in power electronic devices. However, the power device IGBT is prone to various faults in application, wherein an IGBT short-circuit fault is one of the most common faults. Generally, IGBT short-circuit faults can be divided into two categories, namely Hard Switching short-circuit faults (HSF) and Fault Under Load short-circuit faults (full), where a Hard Switching short-circuit Fault refers to a short circuit occurring during the turn-on of the IGBT, and when the IGBT is turned on, the loop impedance is relatively small. The load short-circuit fault means that the load is short-circuited after the IGBT is switched on and enters a stable conduction state. After the IGBT is short-circuited, the current of the device is rapidly increased to 5-10 times that of the IGBT under normal conditions, a large amount of heat is generated and exceeds a safe working area of the device, and because the short-circuit tolerance time of the IGBT of the power device is short, if the short-circuit happens, the IGBT of the power device fails in a short time, the short-circuit fault detection and protection of the IGBT are very important.
There are various schemes for short circuit protection of IGBTs. In the prior art, a series resistance detection technology is adopted to perform short-circuit detection on the IGBT: the short circuit detection circuit is composed of a detection resistor RSHUNTFilter resistor RFFilter capacitor CFAnd a comparator CMPT1, by detecting the resistance RSHUNTThe voltage drop of the voltage source is used for judging whether the circuit is short-circuited or not, and the voltage is generally considered to flow through RSHUNTWhen the current of the resistor reaches 1.7 times of the normal current, the IGBT is judged to be short-circuited, and the detection resistor R is arrangedSHUNTSuch that the resistance R is nowSHUNTVoltage of reaching the short-circuit protection reference threshold VREFT1And the comparator CMPT1 outputs high level, so that the NMOS tube M1 is controlled to be switched on, and the IGBT is switched off. The method is widely adopted by Smart Power Modules (SPM) designed by fairchild semiconductor companies abroad, and has the defects that an isolation circuit is required in a resistance detection method, stray inductance is introduced, instantaneous detection precision and response performance are poor, a detection resistor is required to be connected in series on a main Power high-voltage circuit, the compactness of a main circuit structure is damaged, and loss is large.
The prior art also discloses a method for carrying out short-circuit protection on the IGBT by adopting a desaturation detection method, and the technology does not damage the structural compactness of a main circuit: the desaturation detection circuit mainly comprises a high-voltage diode DSResistance RSThe delay circuit comprises a delay circuit 1, a delay circuit 2, a comparator CMPT2 and an NMOS tube M2. And a cathode of a high-voltage-resistant diode is connected to a collector of the IGBT to detect the desaturation behavior of the IGBT. When the IGBT is in a normal working state, the IGBT works in a saturation region, the voltage of the IGBT collector is very low, and at the moment, the diode DSIn a forward conducting state, the diode DSThe anode voltage being lower than a reference threshold voltage VREFT2When the IGBT has short-circuit fault, the collector current of the IGBTThe voltage of the anode of the diode rises along with the rise of the voltage of the IGBT, when the voltage of the IGBT is larger than a reference threshold value VREFT2When the IGBT short-circuit fault occurs, the IGBT is protected, the time delay circuit 1 has the function of ensuring that the IGBT can be completely conducted, the voltage of a collector electrode and an emitter electrode is reduced to saturation voltage drop, and the time delay circuit 2 has the function of filtering noise signals in work. The short circuit detection and protection scheme has the following disadvantages: firstly, the circuit is not isolated from the power stage, error detection is easy to occur, secondly, due to the existence of the delay circuit 1, the circuit needs 1-5 us of blanking time, and the detection circuit can detect the short-circuit fault, so that the HSF short-circuit fault cannot be quickly detected, the short-circuit detection time is long, and the risk of IGBT damage is increased.
The prior art also discloses a method for carrying out short-circuit protection on the IGBT by adopting a grid charge detection method, the method has high speed for detecting short-circuit faults, and in addition, because a detection circuit in the method is separated from a main high-current power stage circuit, the working characteristics of a power device are less influenced. The detection circuit comprises a grid charge sensing circuit and a comparator CMPT3, and the detection circuit provides a feedback signal for the driving circuit after detecting the short-circuit fault. Output voltage V of grid charge induction circuitQGRepresenting the variation of the gate charge, reference voltage VREFT3Is a gate voltage VGERelated quantity, voltage V during normal operation of the IGBTQGHigher than reference voltage VREFT3Voltage V when short circuit of IGBT occursQGBelow the reference voltage VREFT3The disadvantages of this method are: one is that the grid charge detection circuit design degree of difficulty is big, and the other is that the grid charge variation of low power level IGBT is little, is difficult to distinguish.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a protection method and a circuit for detecting IGBT short-circuit fault at high speed aiming at the defects of the prior art, and the scheme passes through the grid voltage V of the IGBTGEAnd a driving voltage VGGDetecting and respectively judging whether the IGBT isAnd if the HSF short-circuit fault and the FUL short-circuit fault do not occur, the circuit is simple, the detection time is short, and the reliability problem of IGBT short-circuit protection is solved.
Another technical problem to be solved by the present invention is to provide a method for short-circuit fault protection using the protection circuit.
The technical problem to be solved by the present invention is achieved by the following technical means. The invention relates to a protection circuit for detecting IGBT short-circuit fault at high speed, which is characterized in that: comprises a detection control circuit, an HSF short circuit detection circuit, an FUL short circuit detection circuit, an OR gate logic circuit, a gate drive circuit, a soft turn-off circuit and a gate resistor RG；
Output V of the gate drive circuitGGConnected gate resistor RGOne terminal of (1), gate resistance RGThe other end of the detection control circuit is connected with the grid of the power device IGBT, and the detection control circuit detects the grid voltage VGEProcess and output the detection control signal VCPControlling the operation of the HSF short-circuit detection circuit and the FUL short-circuit detection circuit, wherein the input end of the HSF short-circuit detection circuit is connected with the VGGAnd VGEThe HSF short circuit detection circuit outputs an HSF short circuit signal VSC1The input end of the FUL short circuit detection circuit is connected with V and is used as one input end of the OR gate logic circuitGGAnd VGEThe FUL short circuit detection circuit outputs a FUL short circuit signal VSC2As a further input of the OR-gate logic circuit, the OR-gate logic circuit outputting a short-circuit signal VSCThe soft turn-off circuit is used as an input control end of the soft turn-off circuit, performs soft turn-off processing on the IGBT and outputs a locking signal VSTTo the gate drive circuit.
The invention further discloses a preferable technical scheme or technical characteristics of the protection circuit with the function of high-speed detection of the IGBT short-circuit fault, which is characterized in that: the HSF short circuit detection circuit includes: a PMOS transistor MP1, a resistor R1, a capacitor C1 and a comparator CMP1, wherein the source electrode of the PMOS transistor MP1 is connected with the output V of the drive circuitGGThe grid of the PMOS tube is connected with the grid of the IGBT, the drain of the PMOS tube is connected with one end of a resistor R1, the other end of the resistor R1 is connected with one end V of a capacitor C1C1The other terminal of the capacitor C1 is grounded, and the positive input of the comparator CMP1An input terminal reference voltage VREF2The negative input terminal of the comparator CMP1 is connected to one terminal V of the capacitor C1C1The control terminal of the comparator CMP1 is connected to the output V of the gate control circuitCPOutput signal V of comparator CMP1SC1As an output signal for HSF short detection.
The invention further discloses a preferable technical scheme or technical characteristics of the protection circuit with the function of high-speed detection of the IGBT short-circuit fault, which is characterized in that: the FUL short circuit detection circuit includes: a PMOS tube MP2, a resistor R2, a capacitor C2 and a comparator CMP2, wherein the source electrode of the PMOS tube MP2 is connected with the grid electrode of the IGBT, and the grid electrode of the PMOS tube is connected with the output V of the drive circuitGGThe drain of the PMOS tube is connected with one end of a resistor R2, the other end of the resistor R2 is connected with one end V of a capacitor C2C2The other end of the capacitor C2 is grounded, and the negative input end of the comparator CMP2 is connected with a reference voltage VREF3The positive input terminal of the comparator CMP2 is connected to one terminal V of the capacitor C2C2The control terminal of the comparator CMP2 is connected to the output V of the gate control circuitCPComparator CMP2 output signal VSC2As an output signal of the FUL short detection circuit.
The invention further discloses a preferable technical scheme or technical characteristics of the protection circuit with the function of high-speed detection of the IGBT short-circuit fault, which is characterized in that: the gate driving circuit includes: schmitt trigger SMT1, inverter INV1, NAND gate NAND1, AND gate AND1, buffer circuits BUF1 AND BUF2, PMOS pipe MP3, NMOS pipes MN1 AND MN2, AND resistor RD(ii) a Schmitt input terminal as input V of drive circuitINShort-circuit signal VSCThe gate of the NMOS transistor MN1 is connected, the output of the Schmitt trigger is connected with one input end of the NAND gate 1 AND the input end of the inverter INV1, the output end of the inverter INV1 is connected with one input end of the AND gate AND1, AND the resistor RDOne end of the resistor (B) is connected with a source electrode of a PMOS tube MP3 to be connected with a power supply VCC, source ends of an NMOS tube MN1 and an NMOS tube MN2 are connected with a ground GND, and a resistor RDThe other end of the first transistor, the drain of the NMOS transistor MN1, the other input end of the NAND gate 1 AND the other input end of the AND gate AND1 are connected together, the output end of the NAND gate 1 is connected with the input end of the buffer BUF1, the output end of the AND gate AND1 is connected with the input end of the buffer BUF2, AND the output of the BUF1 is connected with the output end of the buffer BUF2The end of the NMOS transistor MP2 is connected with the grid electrode of a PMOS transistor MP3, the output end of the BUF2 is connected with the grid electrode of an NMOS transistor MN2, the drain electrode of the PMOS transistor MP3 and the drain electrode of the NMOS transistor MN2 are connected together to be used as the output V of the drive circuitGG。
The invention further discloses a preferable technical scheme or technical characteristics of the protection circuit with the function of high-speed detection of the IGBT short-circuit fault, which is characterized in that: the soft turn-off circuit comprises: schmitt trigger SMT2, NMOS transistors MN3 and MN4, and resistors R3 and RSOFTCapacitor CGAnd C3, diodes D1 and D2, zener diode Z1; anode of diode D1 and resistor RSOFTOne end of the NMOS tube MN3 is connected with the grid electrode of the power device IGBT, the source electrodes of the NMOS tubes MN3 and MN4 and one end of the capacitor C3 are connected with the ground end GND, the grid electrode of the NMOS tube MN3, one end of the resistor R3 and the cathode of the diode D2 are connected together and used as the input end V of the soft turn-off circuitSCCathode of diode D1 and capacitor CGOne terminal of the first diode is connected with the cathode of a Zener voltage regulator tube Z1, and a capacitor CGThe other end of the Zener voltage-stabilizing tube, the anode of the Zener voltage-stabilizing tube and the drain electrode of an NMOS tube MN3 are connected together, the anode of a diode D2, the other end of a resistor R3, the other end of a capacitor C3 and the input end of a Schmidt trigger SMT2 are connected together, the output end of the Schmidt trigger is connected with the gate electrode of an NMOS tube MN4, the drain electrode of an NMOS tube MN4 and the drain electrode of the resistor R are connected togetherSOFTAre connected together at the other ends.
The invention further discloses a preferable technical scheme or technical characteristics of the protection circuit with the function of high-speed detection of the IGBT short-circuit fault, which is characterized in that: the input signal of the detection control circuit is the grid voltage V of the power deviceGEDetecting the output signal V of the control circuitCPControlling whether the HSF short circuit detection circuit and the FUL short circuit detection circuit work normally or not when the grid voltage V is detectedGEReach the reference threshold value VREF1The detection control circuit outputs VCPThe HSF short circuit detection circuit and the FUL short circuit detection circuit work normally when the level is high; when the gate voltage VGETo be lower than a reference threshold value VREF1The detection control circuit outputs VCPFor low level, the HSF short circuit detection circuit and the FUL short circuit detection circuit are abnormally operated, and the detection circuit outputs VSCIs low.
The invention further discloses a preferable technical scheme or technical characteristics of the protection circuit with the function of high-speed detection of the IGBT short-circuit fault, which is characterized in that: in the HSF short circuit detection circuit: during the turn-on process of the IGBT, if (V)GG-VGE) Is higher than the conduction threshold | V of the PMOS transistor MP1TH1When | is, the PMOS transistor MP1 is turned on to drive the voltage VGGThe capacitor C1 is charged through the PMOS transistor MP1 and the resistor R1, and when the IGBT is turned off, the capacitor C1 discharges through the resistor R1 and the body diode of the PMOS transistor MP1 by utilizing the body diode characteristic of the PMOS transistor.
The invention further discloses a preferable technical scheme or technical characteristics of the protection circuit with the function of high-speed detection of the IGBT short-circuit fault, which is characterized in that: in the FUL short circuit detection circuit: after the IGBT is turned on, if (V)GE-VGG) Is higher than the conduction threshold | V of the PMOS transistor MP2TH2When | is, the PMOS transistor MP2 is turned on to drive the voltage VGGThe capacitor C2 is charged through the PMOS transistor MP2 and the resistor R2, and when the IGBT is turned off, the capacitor C2 discharges through the resistor R2 and the body diode of the PMOS transistor MP2 by utilizing the body diode characteristic of the PMOS transistor.
In the technical scheme of the protection circuit for detecting the short-circuit fault of the IGBT at high speed, the reference voltage V isREF1、VREF2And VREF3Provided by the chip internal reference circuit.
The invention also provides a method for protecting the IGBT short-circuit fault, which is characterized by comprising the following steps: the method uses any one of the protection circuits with high-speed detection of the IGBT short-circuit fault in the technical scheme to realize the protection of the IGBT short-circuit fault; the method is based on the gate drive voltage V of IGBTGGAnd a gate voltage VGEJudging whether the IGBT has HSF short-circuit fault and FUL short-circuit fault or not in different characteristic states in the normal conduction process and the short-circuit fault; the short circuit detection circuit firstly compares the grid voltage VGEDetecting when the gate voltage V is detectedGEWhen the voltage is higher than a set threshold value, starting HSF short circuit detection and FUL short circuit detection, and if short circuit faults are not detected, indicating that the IGBT is in a normal working state; if short-circuit fault is detected, the IGBT is subjected to soft turn-off processing, meanwhile, the grid is locked, and finally, the IGBT is turned offIGBT。
The above method for protecting against IGBT short-circuit fault further preferably adopts the following technical solutions:
when short-circuit fault of IGBT is detected, short-circuit signal VSCWhen the voltage is high, the NMOS transistor MN1 is in a conducting state, the drain voltage of the NMOS transistor MN1 is low, that is, the input terminal X2 of the NAND gate NAND1 AND the input terminal X4 of the AND gate AND1 are low, the output terminal of the NAND gate NAND1 is high, the output terminal of the AND gate AND1 is low, the PMOS transistor MP3 AND the NMOS transistor MN2 are in a shutdown state, AND the gate input signal V is inputGGIndependent of input signal VINThe influence of (a);
when short-circuit fault of IGBT is not detected, short-circuit signal VSCWhen the voltage is low, the NMOS transistor MN1 is in a closed state, the drain voltage of the NMOS transistor MN4 is high, the input end X2 of the NAND gate NAND1 AND the input end X4 of the AND gate AND1 are high, AND the output end of the NAND gate NAND1 AND the output end of the AND gate AND1 are subjected to the input signal VINWhen V isINAt high level, the gate drives the output VGGAt a high level, when VINAt low level, the gate drives the output VGGIs low level;
when the short-circuit fault of IGBT occurs, the short-circuit signal VSC is high level, the NMOS tube MN3 is in conduction state, the Zener diode Z1 breaks down, the grid voltage VSC drops to a lower voltage quickly, the voltage is higher than the conduction voltage of IGBT, the short-circuit current born by IGBT is reduced, the short-circuit endurance time of IGBT is prolonged, and the short-circuit signal V is highSCAfter time delay through a capacitor C3 and a resistor R1, the output V is outputSCT，VSCTOutputting V after being shaped by Schmitt trigger SMT2SOFT，VSOFTThe NMOS transistor MN4 is controlled to be switched on, and the IGBT passes through the resistor RSOFTAnd the NMOS transistor MN4 is turned off slowly.
Compared with the prior art, the invention has the following advantages:
(1) the invention is to the gate drive voltage V of IGBTGGAnd a gate voltage VGEThe detection is carried out, the conduction transient state of the power device is detected, the detection circuit is simple, the short-circuit detection time is short, and the short-circuit fault can be quickly and reliably detectedTherefore, the power device is effectively protected.
(2) The invention does not need to introduce a high-voltage device, the protection circuit is isolated from the power circuit, the power consumption is low, and the integration is easy;
(3) the invention respectively detects two short circuit types of hard switch short circuit fault (HSF) and loaded short circuit Fault (FUL), provides a corresponding detection circuit, and is provided with a detection control circuit to control the working state of the short circuit detection circuit; the soft turn-off circuit performs short-circuit turn-off processing on the IGBT and locks an output signal of the driving circuit.
(4) The invention designs the detection circuit for two short-circuit faults of the IGBT respectively, and compared with the existing grid charge-based detection method, the detection method has the advantages of simple implementation circuit, easy parameter setting and high reliability.
Drawings
FIG. 1 shows the gate drive voltage V of an IGBT in normal turn-on and HSF short circuitGGAnd a gate voltage VGEA comparison plot over time;
FIG. 2 shows the gate drive voltage V of an IGBT under normal turn-on conditions and under FUL short-circuit conditionsGGAnd a gate voltage VGEA comparison plot over time;
FIG. 3 is a schematic circuit diagram of the present invention;
FIG. 4 is a schematic diagram of a gate driving circuit;
FIG. 5 is a schematic diagram of a soft turn-off circuit;
FIG. 6 is a schematic diagram of the detection control circuit during normal turn-on operation of the IGBT;
FIG. 7 is a schematic diagram of the operation of the detection control circuit in the case of HSF short circuit of the IGBT;
FIG. 8 is a schematic diagram of the operation of the detection control circuit in the case of FUL short circuit of the IGBT;
fig. 9 is a schematic flow chart of an IGBT short-circuit protection method.
The specific implementation mode is as follows:
the principles and features of this invention are described below in conjunction with the following drawings, the examples given are intended to illustrate the invention and are not intended to limit the scope of the invention.
As shown in fig. 1, the IGBT gate drive voltage V under normal conduction and under HSF short circuitGGAnd a gate voltage VGETime-dependent contrast diagram in which the gate drive voltage V is shown in dotted lineGGGraph of the change with time, the solid line portion being the gate VGEGraph of the relationship with time.
As shown in fig. 1, when the IGBT is normally turned on, the gate voltage of the IGBT has a miller plateau during the rising process, and the gate driving voltage V is at this timeGGAnd a gate voltage VGEA large difference, and a gate drive voltage V when the IGBT is short-circuited by HSFGGAnd a gate voltage VGEDirect fast linear ramp up to supply voltage VCC, gate drive voltage VGGAnd a gate voltage VGEThe gate charging time of the IGBT under the condition of HSF short circuit is shorter than that of the IGBT under the condition of normal opening, and the difference | V between the gate driving voltage and the gate voltage is found by comparisonGG-VGEThe value of | during the normal on condition is much higher than that in the case of HSF short circuit, and by using this characteristic, the gate voltage V of the IGBT is detectedGEAnd a gate drive voltage VGGTo judge whether the IGBT has HSF short circuit fault.
As shown in FIG. 2, the IGBT has a gate drive voltage V under normal conduction and FUL short circuitGGAnd a gate voltage VGETime-dependent contrast diagram in which the gate drive voltage V is shown in dotted lineGGGraph of the change with time, the solid line portion being the gate VGEGraph of the relationship with time. Collector current I of IGBT under condition of FUL short circuitCRapidly increases and thereby the collector-emitter voltage VCEAlso rapidly increased due to thedv/dtInfluence of, the gate voltage VGEWill also increase, the gate voltage VGEA large overshoot occurs, the overshoot voltage and the gate resistance RGIn the case of a 15V power supply voltage without a gate clamp circuit, the gate voltage can be as high as 25V and higher than the power supply voltage VCC. Therefore, the gate voltage overshoot in the turn-on process of the IGBT is detectedWhether the IGBT has the FUL short-circuit fault or not can be judged.
As shown in FIG. 3, a protection circuit with high-speed IGBT short-circuit fault detection comprises a detection control circuit 001, an HSF short-circuit detection circuit 002, an FUL short-circuit detection circuit 003, an OR gate logic circuit 004, a gate drive circuit 005, a soft turn-off circuit 006 and a gate resistor RGOutput V of the gate driving circuit 005GGConnected gate resistor RGOne terminal of (1), gate resistance RGThe other end of the detection control circuit is connected with the grid of the power device IGBT, and the detection control circuit 001 detects the grid voltage VGEProcess and output the detection control signal VCPControlling the HSF short circuit detection circuit 002 and the FUL short circuit detection circuit 003 to work, wherein the input end of the HSF short circuit detection circuit 002 is connected with VGGAnd VGEThe HSF short circuit detection circuit 002 outputs an HSF short circuit signal VSC1The input terminal of the FUL short circuit detection circuit 003 is connected to V as one input terminal of the OR gate logic circuit 004GGAnd VGEThe FUL short circuit detection circuit 003 outputs a FUL short circuit signal VSC2As another input terminal of the or gate logic circuit 004, the or gate logic circuit (004) outputs a short-circuit signal VSCAs an input control terminal of the soft shutdown circuit 006, the soft shutdown circuit 006 performs soft shutdown processing on the IGBT and outputs a lock signal VSTTo the gate driver circuit 005.
The HSF short circuit detection circuit comprises a PMOS tube MP1, a resistor R1, a capacitor C1 and a comparator CMP1, wherein the source electrode of the PMOS tube MP1 is connected with the output V of the drive circuitGGThe grid of the PMOS tube is connected with the grid of the IGBT, the drain of the PMOS tube is connected with one end of a resistor R1, the other end of the resistor R1 is connected with one end V of a capacitor C1C1The other end of the capacitor C1 is grounded, and the positive input end of the comparator CMP1 is connected with a reference voltage VREF2The negative input terminal of the comparator CMP1 is connected to one terminal V of the capacitor C1C1The control terminal of the comparator CMP1 is connected to the output V of the gate control circuitCPOutput signal V of comparator CMP1SC1As an output signal for HSF short detection;
the FUL short circuit detection circuit comprises a PMOS tube MP2, a resistor R2, a capacitor C2 and a comparator CMP2, wherein the source electrode of the PMOS tube MP2 is connected with the grid electrode of the IGBT, and the grid electrode of the PMOS tubeOutput V of pole connection driving circuitGGThe drain of the PMOS tube is connected with one end of a resistor R2, the other end of the resistor R2 is connected with one end V of a capacitor C2C2The other end of the capacitor C2 is grounded, and the positive input end of the comparator CMP2 is connected with a reference voltage VREF3The negative input terminal of the comparator CMP2 is connected to one terminal V of the capacitor C2C2The control terminal of the comparator CMP2 is connected to the output V of the gate control circuitCPComparator CMP2 output signal VSC2As an output signal of the FUL short detection circuit;
the protection circuit with high-speed detection of IGBT short-circuit fault comprises two detection circuits, one is an HSF short-circuit fault detection circuit, and the other is an FUL short-circuit fault detection circuit, according to the gate drive voltage V of IGBTGGAnd a gate voltage VGEAnd judging whether the IGBT has the HSF short-circuit fault and the FUL short-circuit fault or not according to different characteristic states in the normal conduction process and the short-circuit fault.
When the IGBT normally operates, the specific operating waveform diagram is shown in fig. 6, when the IGBT is normally turned on, the gate voltage of the IGBT has a plateau stage, and at this time, the gate voltage V isGELower than the driving voltage VGGAs in FIG. 1t 1-t 2In the time period, the PMOS transistor MP1 is turned on, and the gate voltage V is at the timeGEThe capacitor C1 is charged through the resistor R1, and the voltage on the capacitor gradually rises when the grid voltage V isGEAbove a reference threshold value VREF1In the meantime, the comparator CMP1 works normally, and the voltage V is obtained after the capacitor C1 is chargedC1Above a reference threshold value VREF2Comparator output voltage VSC1At low level, when the IGBT is completely conducted, the gate voltage V of the IGBTGEIs equal to the driving voltage VGGThe PMOS transistor MP2 is turned off, so the voltage on the capacitor C2 is always at low level, and the output V of the comparator CMP2SC2Is low, so that the short-circuit detection circuit outputs a signal VSCIs low. When the IGBT is turned off, the grid voltage VGGAnd VGEAt low level, PMOS tubes MP1 and MP2 are equivalent to GGMOS devices, capacitor C1 discharges through the body diodes of R1 and MP1, and capacitor C2 discharges through the body diodes of resistors R2 and MP 2.
When the IGBT is sending outWhen HSF short circuit occurs, the specific working waveform diagram is shown in FIG. 7, the gate voltage of IGBT and the gate driving voltage VGGQuickly and linearly rises to the power supply voltage VCC, and the grid voltage V is in the turn-on process of the IGBTGEAnd a driving voltage VGGClose to, and at the same time the gate voltage V is due to the short IGBT on-time in case of short circuitGGThe charge on the capacitor C1 is much less than that in the normal on-state, via the resistor R1, and the voltage V on the capacitorC1Very low, below a set threshold VREF2Therefore, when the gate voltage V isGEReaches a set threshold value VREF1Comparator CMP1 works normally, and comparator CMP1 outputs VSC1At high level, the short circuit detection circuit outputs VSCAnd outputting a high level, and detecting that the IGBT has a short-circuit fault.
When the IGBT is short-circuited by full, the specific operating waveform diagram is shown in fig. 8, in fig. 2t 3At the moment, the IGBT is short-circuited, and the grid voltage V is at the momentGEHigher than the gate drive voltage VGGA gate overshoot phase occurs, see fig. 2t 3-t 4The PMOS transistor MP2 is turned on, so the gate voltage VGGThe capacitor C2 is charged through the resistor R2, and the voltage V on the capacitorC2Gradually rising above a set threshold VREF3While, at the same time, the gate voltage VGEAbove a set threshold VREF1Comparator CMP2 works normally, and comparator CMP2 outputs VSC2At high level, the short circuit detection circuit outputs VSCAnd outputting a high level, and detecting that the IGBT has a short-circuit fault.
The gate driving circuit diagram is shown in fig. 4. The gate drive circuit comprises a Schmitt trigger SMT1, an inverter INV1, a NAND gate NAND1, an AND gate AND1, buffer circuits BUF1 AND BUF2, a PMOS tube MP3, NMOS tubes MN1 AND MN2, AND a resistor RD. Schmitt input terminal as input V of drive circuitINShort-circuit signal VSCThe gate of the NMOS transistor MN1 is connected, the output of the Schmitt trigger is connected with one input end of the NAND gate 1 AND the input end of the inverter INV1, the output end of the inverter INV1 is connected with one input end of the AND gate AND1, AND the resistor RDOne end of the PMOS transistor MP3 is connected with the source electrode of the power supply VCC, NMThe source ends of the OS tubes MN1 and MN2 are connected to the ground GND and the resistor RDThe other end of the first transistor, the drain of the NMOS transistor MN1, the other input end of the NAND gate 1 AND the other input end of the AND gate AND1 are connected together, the output end of the NAND gate 1 is connected with the input end of the buffer BUF1, the output end of the AND gate AND1 is connected with the input end of the buffer BUF2, the output end of the BUF1 is connected with the gate of the PMOS transistor MP3, the output end of the BUF2 is connected with the gate of the NMOS transistor MN2, AND the drain of the PMOS transistor MP3 AND the drain of the NMOS transistor MN2 are connected together to serve as the output V ofGG。
When short-circuit fault of IGBT is detected, short-circuit signal VSCWhen the voltage is high, the NMOS transistor MN1 is in a conducting state, the drain voltage of the NMOS transistor MN1 is low, that is, the input terminal X2 of the NAND gate NAND1 AND the input terminal X4 of the AND gate AND1 are low, the output terminal of the NAND gate NAND1 is high, the output terminal of the AND gate AND1 is low, the PMOS transistor MP3 AND the NMOS transistor MN2 are in a shutdown state, AND the gate input signal V is inputGGIndependent of input signal VINThe influence of (c). When short-circuit fault of IGBT is not detected, short-circuit signal VSCWhen the voltage is low, the NMOS transistor MN1 is in a closed state, the drain voltage of the NMOS transistor MN4 is high, the input end X2 of the NAND gate NAND1 AND the input end X4 of the AND gate AND1 are high, AND the output end of the NAND gate NAND1 AND the output end of the AND gate AND1 are subjected to the input signal VINThe analysis shows that when V isINAt high level, the gate drives the output VGGAt a high level, when VINAt low level, the gate drives the output VGGIs low.
Soft-off circuit as shown in FIG. 5, the soft-off circuit includes a Schmitt trigger SMT2, NMOS transistors MN3 and MN4, and resistors R3 and RSOFTCapacitor CGAnd C3, diodes D1 and D2, zener diode Z1. Anode of diode D1 and resistor RSOFTOne end of the NMOS tube MN3 is connected with the grid electrode of the power device IGBT, the source electrodes of the NMOS tubes MN3 and MN4 and one end of the capacitor C3 are connected with the ground end GND, the grid electrode of the NMOS tube MN3, one end of the resistor R3 and the cathode of the diode D2 are connected together and used as the input end V of the soft turn-off circuitSCCathode of diode D1 and capacitor CGOne terminal of the first diode is connected with the cathode of a Zener voltage regulator tube Z1, and a capacitor CGThe other end of the Zener voltage-stabilizing tube, the anode of the Zener voltage-stabilizing tube and the drain electrode of an NMOS tube MN3 are connected together, the anode of a diode D2, the other end of a resistor R3, the other end of a capacitor C3 and the input end of a Schmidt trigger SMT2 are connected together, the output end of the Schmidt trigger is connected with the gate electrode of an NMOS tube MN4, the drain electrode of an NMOS tube MN4 and the drain electrode of the resistor R are connected togetherSOFTAre connected together at the other ends.
When the IGBT has short-circuit fault, the output signal VSC of the short-circuit detection circuit is high level, the NMOS tube MN3 is in a conducting state, the Zener diode Z1 breaks down, the grid voltage VSC rapidly drops to a lower voltage, the voltage is higher than the conducting voltage of the IGBT, the short-circuit current born by the IGBT is reduced, the short-circuit endurance time of the IGBT is improved, and the short-circuit signal V is highSCAfter time delay through a capacitor C3 and a resistor R1, the output V is outputSCT，VSCTOutputting V after being shaped by Schmitt trigger SMT2SOFT，VSOFTThe NMOS transistor MN4 is controlled to be switched on, and the IGBT passes through the resistor RSOFTAnd the NMOS transistor MN4 is turned off slowly.
Fig. 9 shows a flow chart of a method for short-circuit protection of an IGBT by the circuit shown in fig. 3, when the driver is in operation, the short-circuit detection circuit first applies a gate voltage VGEDetecting when the gate voltage V is detectedGEAnd starting HSF short circuit detection and FUL short circuit detection when the threshold value is higher than the set threshold value, and if the short circuit fault is not detected, indicating that the IGBT is in a normal working state. If short-circuit fault is detected, the IGBT is subjected to soft turn-off processing, meanwhile, the grid electrode is locked, and finally, the IGBT is turned off, and the protection circuit is based on grid electrode voltage V in the turn-on process of the IGBTGEAnd a gate drive voltage VGGThe detection time is short, the detection time is less than 300ns, the soft off time is less than 400ns, and the total short circuit response time is less than 700 ns.
The above description is only a preferred example of the present invention and is not limited to the present invention, and various modifications and changes may be made to the present invention by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (7)

1. The utility model provides a protection circuit with high-speed detection IGBT short-circuit fault which characterized in that: comprises a detection control circuit, an HSF short circuit detection circuit, an FUL short circuit detection circuit, an OR gate logic circuit, a gate drive circuit, a soft turn-off circuit and a gate resistor RG；
Output V of the gate drive circuitGGConnected gate resistor RGOne terminal of (1), gate resistance RGThe other end of the detection control circuit is connected with the grid of the power device IGBT, and the detection control circuit detects the grid voltage VGEProcess and output the detection control signal VCPControlling the operation of the HSF short-circuit detection circuit and the FUL short-circuit detection circuit, wherein the input end of the HSF short-circuit detection circuit is connected with the VGGAnd VGEThe HSF short circuit detection circuit outputs an HSF short circuit signal VSC1The input end of the FUL short circuit detection circuit is connected with V and is used as one input end of the OR gate logic circuitGGAnd VGEThe FUL short circuit detection circuit outputs a FUL short circuit signal VSC2As a further input of the OR-gate logic circuit, the OR-gate logic circuit outputting a short-circuit signal VSCThe soft turn-off circuit is used as an input control end of the soft turn-off circuit, performs soft turn-off processing on the IGBT and outputs a locking signal VSTProviding the grid drive circuit;
the HSF short circuit detection circuit includes: a PMOS transistor MP1, a resistor R1, a capacitor C1 and a comparator CMP1, wherein the source electrode of the PMOS transistor MP1 is connected with the output V of the drive circuitGGThe grid of the PMOS tube is connected with the grid of the IGBT, the drain of the PMOS tube is connected with one end of a resistor R1, the other end of the resistor R1 is connected with one end V of a capacitor C1C1The other end of the capacitor C1 is grounded, and the positive input end of the comparator CMP1 is connected with a reference voltage VREF2The negative input terminal of the comparator CMP1 is connected to one terminal V of the capacitor C1C1The control terminal of the comparator CMP1 is connected to the output V of the gate control circuitCPOutput signal V of comparator CMP1SC1As an output signal for HSF short detection;
the FUL short circuit detection circuit includes: a PMOS tube MP2, a resistor R2, a capacitor C2 and a comparator CMP2, wherein the source electrode of the PMOS tube MP2 is connected with the grid electrode of the IGBT, and the grid electrode of the PMOS tube is connected with the output V of the drive circuitGGThe drain of the PMOS tube is connected with one end of a resistor R2, the other end of the resistor R2 is connected with one end V of a capacitor C2C2The other end of the capacitor C2 is grounded, and the negative input end of the comparator CMP2 is connected with a reference voltage VREF3The positive input terminal of the comparator CMP2 is connected to one terminal V of the capacitor C2C2The control terminal of the comparator CMP2 is connected to the output V of the gate control circuitCPComparator CMP2 output signal VSC2As an output signal of the FUL short detection circuit.
2. The protection circuit with high-speed detection of an IGBT short-circuit fault according to claim 1, characterized in that: the gate driving circuit includes: schmitt trigger SMT1, inverter INV1, NAND gate NAND1, AND gate AND1, buffer circuits BUF1 AND BUF2, PMOS pipe MP3, NMOS pipes MN1 AND MN2, AND resistor RD(ii) a Schmitt input terminal as input V of drive circuitINShort-circuit signal VSCThe gate of the NMOS transistor MN1 is connected, the output of the Schmitt trigger is connected with one input end of the NAND gate 1 AND the input end of the inverter INV1, the output end of the inverter INV1 is connected with one input end of the AND gate AND1, AND the resistor RDOne end of the resistor (B) is connected with a source electrode of a PMOS tube MP3 to be connected with a power supply VCC, source ends of an NMOS tube MN1 and an NMOS tube MN2 are connected with a ground GND, and a resistor RDThe other end of the first transistor, the drain of the NMOS transistor MN1, the other input end of the NAND gate 1 AND the other input end of the AND gate AND1 are connected together, the output end of the NAND gate 1 is connected with the input end of the buffer BUF1, the output end of the AND gate AND1 is connected with the input end of the buffer BUF2, the output end of the BUF1 is connected with the gate of the PMOS transistor MP3, the output end of the BUF2 is connected with the gate of the NMOS transistor MN2, AND the drain of the PMOS transistor MP3 AND the drain of the NMOS transistor MN2 are connected together to serve as the output V ofGG。
3. The protection circuit with high-speed detection of an IGBT short-circuit fault according to claim 1, characterized in that: the soft turn-off circuit comprises: schmitt trigger SMT2, NMOS transistors MN3 and MN4, and resistors R3 and RSOFTCapacitor CGAnd C3, diodes D1 and D2, zener diode Z1; anode of diode D1 and resistor RSOFTIs connected to one end ofThe source electrodes of the NMOS tubes MN3 and MN4 and one end of the capacitor C3 are connected with the ground end GND, the grid electrode of the NMOS tube MN3, one end of the resistor R3 and the cathode of the diode D2 are connected together to be used as an input end V of the soft turn-off circuitSCCathode of diode D1 and capacitor CGOne terminal of the first diode is connected with the cathode of a Zener voltage regulator tube Z1, and a capacitor CGThe other end of the Zener voltage-stabilizing tube, the anode of the Zener voltage-stabilizing tube and the drain electrode of an NMOS tube MN3 are connected together, the anode of a diode D2, the other end of a resistor R3, the other end of a capacitor C3 and the input end of a Schmidt trigger SMT2 are connected together, the output end of the Schmidt trigger is connected with the gate electrode of an NMOS tube MN4, the drain electrode of an NMOS tube MN4 and the drain electrode of the resistor R are connected togetherSOFTAre connected together at the other ends.
4. The protection circuit with high-speed detection of an IGBT short-circuit fault according to claim 1, characterized in that: the input signal of the detection control circuit is the grid voltage V of the power deviceGEDetecting the output signal V of the control circuitCPControlling whether the HSF short circuit detection circuit and the FUL short circuit detection circuit work normally or not when the grid voltage V is detectedGEReach the reference threshold value VREF1The detection control circuit outputs VCPThe HSF short circuit detection circuit and the FUL short circuit detection circuit work normally when the level is high; when the gate voltage VGETo be lower than a reference threshold value VREF1The detection control circuit outputs VCPFor low level, the HSF short circuit detection circuit and the FUL short circuit detection circuit are abnormally operated, and the detection circuit outputs VSCIs low.
5. The protection circuit with high-speed detection of an IGBT short-circuit fault according to claim 1, characterized in that: in the HSF short circuit detection circuit: during the turn-on process of the IGBT, if (V)GG-VGE) Is higher than the conduction threshold | V of the PMOS transistor MP1TH1When | is, the PMOS transistor MP1 is turned on to drive the voltage VGGThe capacitor C1 is charged through the PMOS transistor MP1 and the resistor R1, and when the IGBT is turned off, the capacitor C1 discharges through the resistor R1 and the body diode of the PMOS transistor MP1 by utilizing the body diode characteristic of the PMOS transistor.
6. The protection circuit with high-speed detection of an IGBT short-circuit fault according to claim 1, characterized in that: in the FUL short circuit detection circuit: after the IGBT is turned on, if (V)GE-VGG) Is higher than the conduction threshold | V of the PMOS transistor MP2TH2When | is, the PMOS transistor MP2 is turned on to drive the voltage VGGThe capacitor C2 is charged through the PMOS transistor MP2 and the resistor R2, and when the IGBT is turned off, the capacitor C2 discharges through the resistor R2 and the body diode of the PMOS transistor MP2 by utilizing the body diode characteristic of the PMOS transistor.
7. A method for protecting IGBT short-circuit fault is characterized in that: the method realizes IGBT short-circuit fault protection by using the protection circuit with high-speed detection of IGBT short-circuit faults as claimed in any one of claims 1 to 6; the method is based on the gate drive voltage V of IGBTGGAnd a gate voltage VGEJudging whether the IGBT has HSF short-circuit fault and FUL short-circuit fault or not in different characteristic states in the normal conduction process and the short-circuit fault; the detection control circuit firstly detects the gate voltage VGE, when the gate voltage VGE is higher than a set threshold value, HSF short circuit detection and FUL short circuit detection are started, and if no short circuit fault is detected, the IGBT is in a normal working state; and if the short-circuit fault is detected, performing soft turn-off processing on the IGBT and locking the grid at the same time, and finally turning off the IGBT.
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