A method for over-current protection of a high-power IGBT

Abstract

The application relates to a large-power IGBT overcurrent protection method, and belongs to the technical field of IGBT protection, which solves the problems of reduced service life and misoperation caused by the large-power IGBT protection in the prior art. The overcurrent protection method comprises the following steps: detecting a turn-on and turn-off signal of a large-power IGBT; collecting a collector voltage of the large-power IGBT, judging whether the collector voltage is greater than a voltage threshold value, and obtaining a voltage judgment result; collecting a collector current of the large-power IGBT, judging whether the collector current is greater than a current threshold value, and obtaining a current judgment result; determining whether to perform overcurrent protection on the large-power IGBT according to the turn-on and turn-off signal, the voltage judgment result and the current judgment result; and if yes, slowly pulling down a gate voltage through a soft turn-off circuit to perform overcurrent protection. The application realizes accurate protection of the large-power IGBT, reduces misoperation and improves the service life.

Description

Technical Field

[0001] This invention relates to the field of IGBT protection technology, and in particular to an overcurrent protection method for high-power IGBTs. Background Technology

[0002] Power devices such as IGBTs (Insulated Gate Bipolar Transistors) are widely used in power electronic equipment such as solar inverters, charging piles, and traction converters as semiconductor switching devices.

[0003] With the rapid development of power devices IGBTs, ensuring the safe and reliable operation of power devices IGBTs has become increasingly important, and at the same time, the drivers that play the switching and protection roles of IGBTs have also developed rapidly.

[0004] In existing technologies, short-circuit detection methods for IGBT drivers mainly include VCE voltage desaturation detection and di / dt short-circuit overcurrent detection. The VCE voltage desaturation detection method, due to the increased overcurrent time caused by the delay time, will accelerate the aging of the device and shorten its service life. The di / dt short-circuit overcurrent detection method, for ordinary currents with a small current rise rate, requires a low short-circuit threshold due to the small voltage drop on the parasitic inductance, which can easily cause false tripping of the short-circuit protection.

[0005] Therefore, there is an urgent need for a new technical solution to protect power devices such as IGBTs. Summary of the Invention

[0006] Based on the above analysis, the present invention aims to provide an overcurrent protection method for high-power IGBTs to solve the problems of reduced service life and malfunction caused by high-power IGBT protection in the prior art.

[0007] This invention provides an overcurrent protection method for high-power IGBTs, the overcurrent protection method comprising:

[0008] Detecting the on / off signals of high-power IGBTs;

[0009] The collector voltage of a high-power IGBT is collected, and it is determined whether the collector voltage is greater than the voltage threshold to obtain the voltage judgment result.

[0010] Collect the collector current of a high-power IGBT, determine whether the collector current is greater than the current threshold, and obtain the current judgment result.

[0011] Determine whether to perform overcurrent protection for high-power IGBTs based on the on / off signal, voltage judgment result, and current judgment result; if yes, perform overcurrent protection by slowly lowering the gate voltage through a soft turn-off circuit.

[0012] Based on a further improvement to the above method, the acquisition of the collector voltage of the high-power IGBT includes: acquiring the collector voltage of the high-power IGBT through a collector voltage detection circuit; wherein,

[0013] The collector voltage detection circuit includes a second resistor R2, a capacitor C1, and a second diode D2;

[0014] The negative terminal of the second diode D2 is connected to the collector of the high-power IGBT, and the positive terminal of the second diode D2 is connected to one end of the capacitor C1 and one end of the second resistor R2. The other end of the second resistor R2 is connected to the positive power supply VCC, and the other end of the capacitor C1 is connected to the negative power supply VEE. The collector voltage is output from the positive terminal of the second diode D2.

[0015] Based on the further improvement of the above method, the collector voltage detection circuit transmits the collected collector voltage to the second comparator, and the second comparator determines whether the collector voltage is greater than the voltage threshold to obtain the voltage judgment result.

[0016] The positive input terminal of the second comparator receives the collector voltage, the negative input terminal receives the voltage threshold, and the output terminal of the second comparator outputs the voltage judgment result.

[0017] Based on a further improvement of the above method, the collector voltage detection circuit further includes a third diode D3 and a fourth diode D4;

[0018] The negative terminal of the third diode D3 is connected to the positive power supply VCC, and the positive terminal of the third diode D3 is connected to the positive terminal of the second diode D2.

[0019] The positive terminal of the fourth diode D4 is connected to the negative power supply VEE, and the negative terminal of the fourth diode D4 is connected to the positive terminal of the second diode D2.

[0020] Based on a further improvement to the above method, the acquisition of the collector current of the high-power IGBT includes: acquiring the collector current of the high-power IGBT through a collector current detection circuit; wherein,

[0021] The collector current detection circuit includes a current Hall effect sensor L and a first resistor R1;

[0022] The detection terminal of the current Hall L is connected to the collector of the high-power IGBT to collect the collector current; the output terminal of the current Hall L is connected to one end of the first resistor R1, and the other end of the first resistor R1 is grounded; the output terminal of the current Hall L outputs the collector current.

[0023] Based on the further improvement of the above method, the collector current detection circuit transmits the detected collector current to the first comparator, and the first comparator determines whether the collector current is greater than the current threshold to obtain the current judgment result.

[0024] The positive input terminal of the first comparator receives the collector current, the negative input terminal of the first comparator receives the current threshold, and the output terminal of the first comparator outputs the current judgment result.

[0025] A further improvement to the above method, the step of determining whether to provide overcurrent protection for high-power IGBTs based on the on / off signal, voltage judgment result, and current judgment result, includes:

[0026] If the turn-on / turn-off signal is a turn-on signal, the voltage judgment result is that the collector voltage is greater than the voltage threshold, and the current judgment result is that the collector current is greater than the current threshold, then an overcurrent protection control signal is output to provide overcurrent protection for the high-power IGBT.

[0027] Based on a further improvement of the above method, the soft shutdown circuit includes a third MOSFET Q3 and a third resistor R3; the gate of the third MOSFET Q3 is used to receive a control signal for whether to perform overcurrent protection on the high-power IGBT.

[0028] The source of the third MOSFET Q3 is connected to the negative power supply VEE, and the drain of the third MOSFET Q3 is connected to one end of the third resistor R3. The other end of the third resistor R3 is connected to the gate of the high-power IGBT, which is used to reduce the gate voltage of the high-power IGBT and turn it off.

[0029] Based on further improvements to the above method, a logic circuit receives the on / off signals, voltage judgment results, and current judgment results to determine whether to provide overcurrent protection for the high-power IGBT; among which,

[0030] Logic circuits include NOT gates G INV1 First AND gate G AND1 Second AND gate G AND2 ;

[0031] NOT gate G INV1 The input terminal receives the turn-on / turn-off signal generated by the PWM control generator, and the NOT gate G... INV1 The output terminal is connected to the first AND gate G. AND1 One input terminal, the first AND gate G AND1 The other input is used to receive the voltage judgment result, the first AND gate G AND1 The output terminal is connected to the second AND gate G. AND2 One input terminal; the second AND gate G AND2 The other input is used to receive the current judgment result, the second AND gate G AND2The output terminal generates a control signal to determine whether to perform overcurrent protection on high-power IGBTs.

[0032] The PWM control generator is used to generate the turn-on and turn-off signals of the high-power IGBT; when the turn-on and turn-off signal is a high-level signal, the high-power IGBT is in the off state; when the turn-on and turn-off signal is a low-level signal, the high-power IGBT is in the on state.

[0033] The PWM control generator is used to generate the turn-on and turn-off signals of the high-power IGBT; when the turn-on and turn-off signal is a high-level signal, the high-power IGBT is in the off state; when the turn-on and turn-off signal is a low-level signal, the high-power IGBT is in the on state.

[0034] Based on the further improvement of the above method, the turn-on and turn-off signals control the turn-on and turn-off of the high-power IGBT through a push-pull amplifier circuit; the push-pull amplifier circuit includes a first MOSFET Q1, a second MOSFET Q2, a turn-on resistor Ron, and a turn-off resistor Roff.

[0035] The source of the first MOSFET Q1 is connected to the positive power supply VCC, and the source of the second MOSFET Q2 is connected to the negative power supply VEE; the gates of the first MOSFET Q1 and the second MOSFET Q2 are simultaneously connected to the PWM control generator to receive the turn-on and turn-off signals.

[0036] The drain of the first MOSFET Q1 is connected to one end of the on-resistance Ron, and the drain of the second MOSFET Q2 is connected to one end of the off-resistance Roff. The other end of the on-resistance Ron and one end of the off-resistance Roff are connected to the gate of the high-power IGBT to generate a gate voltage to control the on and off of the high-power IGBT.

[0037] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0038] By detecting the on / off signals, collector voltage, and collector current, and combining them with preset voltage and current thresholds, if it is determined that overcurrent protection is needed for a high-power IGBT, the gate voltage is slowly lowered through a soft-shutdown circuit to perform overcurrent protection, reducing false tripping of the protection and improving the service life of the high-power IGBT.

[0039] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0040] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0041] Figure 1 A flowchart illustrating the overcurrent protection method for high-power IGBTs provided in an embodiment of the present invention;

[0042] Figure 2 This is a schematic diagram of the overcurrent protection circuit for a high-power IGBT provided in an embodiment of the present invention. Detailed Implementation

[0043] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0044] IGBTs have high voltage and current handling capabilities, as well as fast switching speeds, and are widely used in power electronics fields such as frequency converters, inverters, electric vehicle drive systems, and power transmission and distribution systems.

[0045] One specific embodiment of the present invention discloses an overcurrent protection method for a high-power IGBT, where a high-power IGBT refers to an IGBT with a rated power greater than 1KW, such as... Figure 1 As shown, the overcurrent protection method includes:

[0046] Step S1: Detect the on / off signal of the high-power IGBT;

[0047] Step S2: Collect the collector voltage of the high-power IGBT, determine whether the collector voltage is greater than the voltage threshold, and obtain the voltage judgment result;

[0048] Step S3: Collect the collector current of the high-power IGBT, determine whether the collector current is greater than the current threshold, and obtain the current judgment result;

[0049] Step S4: Determine whether to perform overcurrent protection for high-power IGBTs based on the turn-on / turn-off signal, voltage judgment result, and current judgment result; if yes, perform overcurrent protection by slowly lowering the gate voltage through a soft turn-off circuit.

[0050] Specifically, high-power IGBTs are turned on or off by the gate voltage connected to their gate. When on, a positive gate voltage is applied to the gate relative to the emitter, forming an N-channel between the P-type substrate and the N-type drift layer below the gate. This N-channel connects the collector and emitter, allowing current to flow through the IGBT, and the IGBT is in the on state. When off, the gate voltage drops below the turn-on threshold voltage, the N-channel disappears, the current path between the collector and emitter is cut off, and the IGBT enters the off state.

[0051] Specifically, such as Figure 1 As shown, when performing overcurrent protection on high-power IGBTs, steps S1, S2, and S3 can be executed synchronously or asynchronously. The turn-on / turn-off signals, voltage judgment results, and current judgment results obtained from steps S1, S2, and S3 are transmitted to step S4, where they are jointly used to determine whether to perform overcurrent protection on the high-power IGBTs.

[0052] Specifically, if overcurrent protection for high-power IGBTs is not required, no protection action will be taken; if it is determined that overcurrent protection for high-power IGBTs is required, the gate voltage connected to the gate of the high-power IGBT needs to be slowly lowered through a soft-shutdown circuit to turn off the high-power IGBT and prevent it from being damaged.

[0053] Specifically, in step S1, the on / off signals of the high-power IGBT include two types: one is an on signal used to put the high-power IGBT in the on state, and the other is an off signal used to put the high-power IGBT in the off state.

[0054] Specifically, in step S2, the voltage threshold is a preset safe voltage. When the collector voltage is greater than the voltage threshold, the high-power IGBT may be in the on state and the high-power IGBT is in the overcurrent short-circuit state.

[0055] Specifically, in step S3, the current threshold is a preset safe current. When the collector current is greater than the current threshold, the high-power IGBT may be in the on state and the high-power IGBT is in the overcurrent short-circuit state.

[0056] Specifically, in step S4, based on the turn-on / turn-off signals, voltage judgment results, and current judgment results obtained in steps 1, 2, and S3, it is determined whether to perform overcurrent protection on the high-power IGBT.

[0057] Preferably, determining whether to provide overcurrent protection for the high-power IGBT based on the on / off signal, voltage judgment result, and current judgment result includes:

[0058] If the turn-on / turn-off signal is a turn-on signal, the voltage judgment result is that the collector voltage is greater than the voltage threshold, and the current judgment result is that the collector current is greater than the current threshold, then an overcurrent protection control signal is output to provide overcurrent protection for the high-power IGBT.

[0059] Specifically, when the turn-on / turn-off signal is a turn-on signal, the voltage judgment result is that the collector voltage is greater than the voltage threshold, and the current judgment result is that the collector current is greater than the current threshold, it can be determined that the high-power IGBT is in a short-circuit overcurrent situation. At this time, overcurrent protection needs to be implemented for the high-power IGBT. Overcurrent protection is achieved by slowly lowering the gate voltage of the high-power IGBT through a soft turn-off circuit.

[0060] Preferably, the acquisition of the collector voltage of the high-power IGBT includes: acquiring the collector voltage of the high-power IGBT through a collector voltage detection circuit; wherein,

[0061] The collector voltage detection circuit includes a second resistor R2, a capacitor C1, and a second diode D2;

[0062] The negative terminal of the second diode D2 is connected to the collector of the high-power IGBT, and the positive terminal of the second diode D2 is connected to one end of the capacitor C1 and one end of the second resistor R2. The other end of the second resistor R2 is connected to the positive power supply VCC, and the other end of the capacitor C1 is connected to the negative power supply VEE. The collector voltage is output from the positive terminal of the second diode D2.

[0063] Specifically, such as Figure 2 As shown, the collector voltage of a high-power IGBT is acquired through a collector voltage detection circuit. The second diode D2 conducts under the influence of the positive power supply VCC. When the collector voltage of the high-power IGBT rises, the positive voltage of the second diode D2 is greater than the negative voltage by the diode's forward voltage, causing the positive voltage of the second diode D2 to rise synchronously. At this time, the positive voltage of the second diode D2 can be used to represent the collector voltage of the high-power IGBT. The positive voltage of the second diode D2 is changed by charging and discharging the capacitor C1.

[0064] Preferably, the collector voltage detection circuit transmits the acquired collector voltage to the second comparator, and the second comparator determines whether the collector voltage is greater than the voltage threshold to obtain the voltage judgment result.

[0065] The positive input terminal of the second comparator receives the collector voltage, the negative input terminal receives the voltage threshold, and the output terminal of the second comparator outputs the voltage judgment result.

[0066] Specifically, such as Figure 2As shown, the positive voltage of the second diode D2 is connected to the positive input terminal of the second comparator U2, and the voltage threshold is set to the reference voltage Vref2 of the second comparator U2 and connected to the negative input terminal of the second comparator U2. The second comparator U2 compares the collector voltage and the voltage threshold to obtain the voltage judgment result, and the voltage judgment result is output through the output terminal of the second comparator U2.

[0067] Preferably, the collector voltage detection circuit further includes a third diode D3 and a fourth diode D4;

[0068] The negative terminal of the third diode D3 is connected to the positive power supply VCC, and the positive terminal of the third diode D3 is connected to the positive terminal of the second diode D2.

[0069] The positive terminal of the fourth diode D4 is connected to the negative power supply VEE, and the negative terminal of the fourth diode D4 is connected to the positive terminal of the second diode D2.

[0070] Specifically, a third diode D3 and a fourth diode D4 are added to the collector voltage detection circuit. When the collector voltage of the high-power IGBT increases instantaneously due to interference, the third diode D3 and the fourth diode D4 can keep the positive voltage of the second diode D2 within the range of the positive power supply VCC and the negative power supply VEE, thus protecting the collector voltage detection circuit.

[0071] Preferably, the acquisition of the collector current of the high-power IGBT includes: acquiring the collector current of the high-power IGBT through a collector current detection circuit; wherein,

[0072] The collector current detection circuit includes a current Hall effect sensor L and a first resistor R1;

[0073] The detection terminal of the current Hall L is connected to the collector of the high-power IGBT to collect the collector current; the output terminal of the current Hall L is connected to one end of the first resistor R1, and the other end of the first resistor R1 is grounded; the output terminal of the current Hall L outputs the collector current.

[0074] Specifically, such as Figure 2 As shown, the collector current of the high-power IGBT is acquired through a collector current detection circuit. The detection terminal of the current Hall L is connected to the collector of the high-power IGBT to detect the collector current of the high-power IGBT. The first resistor R1 is used to sample the acquired collector current.

[0075] Preferably, the collector current detection circuit transmits the detected collector current to the first comparator, and the first comparator determines whether the collector current is greater than the current threshold to obtain the current judgment result.

[0076] The positive input terminal of the first comparator receives the collector current, the negative input terminal of the first comparator receives the current threshold, and the output terminal of the first comparator outputs the current judgment result.

[0077] Specifically, such as Figure 2 As shown, in the collector current detection circuit, one end of the first resistor R1 is connected to the positive input terminal of the first comparator U1, that is, the collector current is input into the first comparator. The negative input terminal of the first comparator is used to set the current threshold, which serves as the reference voltage Vref1 of the first comparator. After comparing the collector current with the current threshold, the first comparator U1 obtains the current judgment result, which is output through the output terminal of the first comparator U1.

[0078] Preferably, such as Figure 2 As shown, the soft-shutdown circuit includes a third MOSFET Q3 and a third resistor R3; the gate of the third MOSFET Q3 is used to receive a control signal for whether to perform overcurrent protection on the high-power IGBT.

[0079] The source of the third MOSFET Q3 is connected to the negative power supply VEE, and the drain of the third MOSFET Q3 is connected to one end of the third resistor R3. The other end of the third resistor R3 is connected to the gate of the high-power IGBT, which is used to reduce the gate voltage of the high-power IGBT and turn it off.

[0080] Specifically, the gate of the third MOSFET Q3 is used to receive control signals for overcurrent protection of the high-power IGBT and control signals for not providing overcurrent protection. When the gate of the third MOSFET Q3 receives the control signal for overcurrent protection of the high-power IGBT, it turns on the third MOSFET Q3. After the third MOSFET Q3 turns on, it divides the gate voltage of the high-power IGBT through the third resistor R3, causing the gate voltage of the high-power IGBT to decrease slowly. After the gate voltage decreases to a certain level, the high-power IGBT will be turned off, thereby achieving overcurrent protection for the high-power IGBT.

[0081] Preferably, the system receives the on / off signal, voltage judgment result, and current judgment result through logic circuitry, and determines whether to provide overcurrent protection for the high-power IGBT; wherein,

[0082] Logic circuits include NOT gates G INV1 First AND gate G AND1 Second AND gate G AND2 ;

[0083] NOT gate G INV1 The input terminal receives the turn-on / turn-off signal generated by the PWM control generator, and the NOT gate G... INV1 The output terminal is connected to the first AND gate G. AND1One input terminal, the first AND gate G AND1 The other input is used to receive the voltage judgment result, the first AND gate G AND1 The output terminal is connected to the second AND gate G. AND2 One input terminal; the second AND gate G AND2 The other input is used to receive the current judgment result, the second AND gate G AND2 The output terminal generates a control signal to determine whether to perform overcurrent protection on high-power IGBTs.

[0084] The PWM control generator is used to generate the turn-on and turn-off signals of the high-power IGBT; when the turn-on and turn-off signal is a high-level signal, the high-power IGBT is in the off state; when the turn-on and turn-off signal is a low-level signal, the high-power IGBT is in the on state.

[0085] Specifically, such as Figure 2 As shown, the NOT gate G included in the logic circuit INV1 First AND gate G AND1 Second AND gate G AND2 Logical judgments are performed on the on / off signals, voltage judgment results, and current judgment results to determine whether to apply overcurrent protection to the high-power IGBT. Finally, the result is passed through the second AND gate G. AND2 The output is sent to the soft-shutdown circuit, which in turn controls the on and off states of the high-power IGBT.

[0086] like Figure 2 As shown, the PWM control generator is used to generate the turn-on and turn-off signals for the high-power IGBT. For example, when the turn-on / turn-off signal is high, the high-power IGBT is in the off state; when the turn-on / turn-off signal is low, the high-power IGBT is in the on state. The turn-on and turn-off signals of the high-power IGBT can be determined by receiving the high and low level signals emitted by the PWM control generator.

[0087] Preferably, the turn-on and turn-off signals control the turn-on and turn-off of the high-power IGBT through a push-pull amplifier circuit; the push-pull amplifier circuit includes a first MOSFET Q1, a second MOSFET Q2, a turn-on resistor Ron, and a turn-off resistor Roff;

[0088] The source of the first MOSFET Q1 is connected to the positive power supply VCC, and the source of the second MOSFET Q2 is connected to the negative power supply VEE; the gates of the first MOSFET Q1 and the second MOSFET Q2 are simultaneously connected to the PWM control generator to receive the turn-on and turn-off signals.

[0089] The drain of the first MOSFET Q1 is connected to one end of the on-resistance Ron, and the drain of the second MOSFET Q2 is connected to one end of the off-resistance Roff. The other end of the on-resistance Ron and one end of the off-resistance Roff are connected to the gate of the high-power IGBT to generate a gate voltage to control the on and off of the high-power IGBT.

[0090] Specifically, such as Figure 2 As shown, the push-pull amplifier circuit operates according to the high-level and low-level signals generated by the PWM control generator. When the PWM control generator generates a high-level signal, it turns on the second MOSFET Q2 and turns off the first MOSFET. This pulls the gate voltage of the high-power IGBT to around the negative power supply VEE, thus putting the high-power IGBT in the off state. When the PWM control generator generates a low-level signal, it turns on the first MOSFET Q1 and turns off the second MOSFET. This pulls the gate voltage of the high-power IGBT to around the positive power supply VCC, thus putting the high-power IGBT in the on state.

[0091] Specifically, the on-resistance Ron and the off-resistance Roff can be variable resistors, thereby adjusting the switching speed of high-power IGBTs.

[0092] Specifically, such as Figure 2 As shown, the high-level and low-level signals generated by the PWM control generator are relatively weak. These are amplified by a push-pull amplifier circuit to provide sufficient drive voltage for the high-power IGBT's turn-on and turn-off. When the PWM control generator generates a high-level signal, the second MOSFET Q2 is turned on, and the gate voltage of the high-power IGBT is VEE, at which point the high-power IGBT is in the off state. When the PWM control generator generates a low-level signal, the first MOSFET Q1 is turned on, and the gate voltage of the high-power IGBT is VCC, at which point the high-power IGBT is in the on state.

[0093] Specifically, such as Figure 2 As shown, the collector current detection circuit uses a current Hall L to detect the collector current of a high-power IGBT, and adjusts the current threshold by adjusting the reference voltage Vref1.

[0094] It is worth noting that when the PWM controller generates a high-level signal, the push-pull amplifier circuit will turn off the high-power IGBT. At this time, regardless of the voltage and current judgment results, the logic circuit will still control the high-power IGBT through the second AND gate G. AND2 A low output level prevents the soft shutdown circuit from operating.

[0095] When the PWM controller generates a low-level signal, the first MOSFET Q1 turns on, the high-power IGBT is on, and the NOT gate G... INV1 When the collector voltage detection circuit detects an overcurrent signal and outputs a high-level signal, the first AND gate G... AND1 When the collector current detection circuit detects an overcurrent signal and outputs a high-level signal, the second AND gate G... AND2 When a high-level signal is output, the third MOSFET Q3 is turned on, and the soft-shutdown circuit is activated, thereby turning off the high-power IGBT.

[0096] Compared with the prior art, the overcurrent protection method for high-power IGBTs provided in this embodiment of the invention detects the turn-on / turn-off signal, collector voltage, and collector current, and combines them with preset voltage and current thresholds. If it is determined that overcurrent protection is required for the high-power IGBT, the overcurrent protection is performed by slowly lowering the gate voltage through a soft turn-off circuit. This reduces the false tripping of the protection and improves the service life of the high-power IGBT.

[0097] Those skilled in the art will understand that all or part of the processes of the methods described in the above embodiments can be implemented by a computer program instructing related hardware, and the program can be stored in a computer-readable storage medium. The computer-readable storage medium may be a disk, optical disk, read-only memory, or random access memory, etc.

[0098] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. An overcurrent protection method for a high-power IGBT, characterized in that, The overcurrent protection method includes: Detecting the on / off signals of high-power IGBTs; The collector voltage of a high-power IGBT is collected, and it is determined whether the collector voltage is greater than the voltage threshold to obtain the voltage judgment result. Collect the collector current of a high-power IGBT, determine whether the collector current is greater than the current threshold, and obtain the current judgment result. Determine whether to perform overcurrent protection for high-power IGBTs based on the on / off signal, voltage judgment result, and current judgment result; if yes, perform overcurrent protection by slowly lowering the gate voltage through a soft turn-off circuit. The process of determining whether to provide overcurrent protection for high-power IGBTs based on the on / off signal, voltage judgment result, and current judgment result includes: If the turn-on / turn-off signal is a turn-on signal, the voltage judgment result is that the collector voltage is greater than the voltage threshold, and the current judgment result is that the collector current is greater than the current threshold, then an overcurrent protection control signal is output to provide overcurrent protection for the high-power IGBT. The logic circuit receives the on / off signals, voltage judgment results, and current judgment results, and determines whether to provide overcurrent protection for the high-power IGBT; among which, Logic circuits include NOT gates G INV1 First AND gate G AND1 Second AND gate G AND2 ; NOT gate G INV1 The input terminal receives the turn-on / turn-off signal generated by the PWM control generator, and the NOT gate G... INV1 The output terminal is connected to the first AND gate G. AND1 One input terminal, the first AND gate G AND1 The other input is used to receive the voltage judgment result, the first AND gate G AND1 The output terminal is connected to the second AND gate G. AND2 One input terminal; the second AND gate G AND2 The other input is used to receive the current judgment result, the second AND gate G AND2 The output terminal generates a control signal to determine whether to perform overcurrent protection on high-power IGBTs; The PWM control generator is used to generate the turn-on and turn-off signals of the high-power IGBT; when the turn-on and turn-off signal is a high-level signal, the high-power IGBT is in the off state; when the turn-on and turn-off signal is a low-level signal, the high-power IGBT is in the on state.

2. The overcurrent protection method according to claim 1, characterized in that, The acquisition of the collector voltage of the high-power IGBT includes: acquiring the collector voltage of the high-power IGBT through a collector voltage detection circuit; wherein... The collector voltage detection circuit includes a second resistor R2, a capacitor C1, and a second diode D2; The negative terminal of the second diode D2 is connected to the collector of the high-power IGBT, and the positive terminal of the second diode D2 is connected to one end of the capacitor C1 and one end of the second resistor R2. The other end of the second resistor R2 is connected to the positive power supply VCC, and the other end of the capacitor C1 is connected to the negative power supply VEE. The collector voltage is output from the positive terminal of the second diode D2.

3. The overcurrent protection method according to claim 2, characterized in that, The collector voltage detection circuit transmits the acquired collector voltage to the second comparator, which determines whether the collector voltage is greater than the voltage threshold and obtains the voltage judgment result. The positive input terminal of the second comparator receives the collector voltage, the negative input terminal receives the voltage threshold, and the output terminal of the second comparator outputs the voltage judgment result.

4. The overcurrent protection method according to claim 2, characterized in that, The collector voltage detection circuit also includes a third diode D3 and a fourth diode D4; The negative terminal of the third diode D3 is connected to the positive power supply VCC, and the positive terminal of the third diode D3 is connected to the positive terminal of the second diode D2. The positive terminal of the fourth diode D4 is connected to the negative power supply VEE, and the negative terminal of the fourth diode D4 is connected to the positive terminal of the second diode D2.

5. The overcurrent protection method according to claim 1, characterized in that, The acquisition of the collector current of the high-power IGBT includes: acquiring the collector current of the high-power IGBT through a collector current detection circuit; wherein, The collector current detection circuit includes a current Hall effect sensor L and a first resistor R1; The detection terminal of the current Hall L is connected to the collector of the high-power IGBT to collect the collector current; the output terminal of the current Hall L is connected to one end of the first resistor R1, and the other end of the first resistor R1 is grounded; the output terminal of the current Hall L outputs the collector current.

6. The overcurrent protection method according to claim 5, characterized in that, The collector current detection circuit transmits the detected collector current to the first comparator, which determines whether the collector current is greater than the current threshold and obtains the current judgment result. The positive input terminal of the first comparator receives the collector current, the negative input terminal of the first comparator receives the current threshold, and the output terminal of the first comparator outputs the current judgment result.

7. The overcurrent protection method according to any one of claims 1-6, characterized in that, The soft-shutdown circuit includes a third MOSFET Q3 and a third resistor R3; the gate of the third MOSFET Q3 is used to receive a control signal for whether to perform overcurrent protection on the high-power IGBT. The source of the third MOSFET Q3 is connected to the negative power supply VEE, and the drain of the third MOSFET Q3 is connected to one end of the third resistor R3. The other end of the third resistor R3 is connected to the gate of the high-power IGBT, which is used to reduce the gate voltage of the high-power IGBT and turn it off.

8. The overcurrent protection method according to claim 1, characterized in that, The turn-on and turn-off signals control the turn-on and turn-off of the high-power IGBT through a push-pull amplifier circuit; the push-pull amplifier circuit includes a first MOSFET Q1, a second MOSFET Q2, a turn-on resistor Ron, and a turn-off resistor Roff; The source of the first MOSFET Q1 is connected to the positive power supply VCC, and the source of the second MOSFET Q2 is connected to the negative power supply VEE; the gates of the first MOSFET Q1 and the second MOSFET Q2 are simultaneously connected to the PWM control generator to receive the turn-on and turn-off signals. The drain of the first MOSFET Q1 is connected to one end of the on-resistance Ron, and the drain of the second MOSFET Q2 is connected to one end of the off-resistance Roff. The other ends of the on-resistance Ron and the other ends of the off-resistance Roff are connected to the gate of the high-power IGBT to generate a gate voltage to control the on and off of the high-power IGBT.

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