Overcurrent protection method for high-power IGBT (Insulated Gate Bipolar Translator)

Abstract

The invention relates to an overcurrent protection method for a high-power IGBT (Insulated Gate Bipolar Translator), belongs to the technical field of IGBT protection, and solves the problems of shortened service life and misoperation caused by high-power IGBT protection in the prior art. The over-current protection method comprises the following steps: detecting a turn-on and turn-off signal of a high-power IGBT; collecting the collector voltage of the high-power IGBT, judging whether the collector voltage is greater than a voltage threshold value or not, and obtaining a voltage judgment result; collecting the collector current of the high-power IGBT, judging whether the collector current is greater than a current threshold value or not, and obtaining a current judgment result; according to the on-off signal, the voltage judgment result and the current judgment result, whether over-current protection is carried out on the high-power IGBT or not is determined; and if so, slowly lowering the gate voltage through the soft turn-off circuit to carry out overcurrent protection. Accurate protection of the high-power IGBT is achieved, misoperation is reduced, and the service life is prolonged.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of IGBT protection, in particular to an overcurrent protection method for a high-power IGBT. BACKGROUND

[0002] The power device IGBT (Insulated Gate Bipolar Transistor) is widely used in power electronic devices such as solar inverters, charging piles, traction converters, etc. as a semiconductor switching device.

[0003] With the rapid development of the power device IGBT, it is more and more important to ensure the safe and reliable operation of the power device IGBT, and the driver which plays a switching role and a protection role has also been rapidly developed.

[0004] In the prior art, the short-circuit detection methods of IGBT driving mainly include the VCE voltage desaturation detection method and the di / dt short-circuit overcurrent detection method. The VCE voltage desaturation detection method will accelerate the aging of the device and shorten the service life due to the increased overcurrent time of the delay time. The di / dt short-circuit overcurrent detection method needs to set a lower short-circuit threshold value because the voltage drop on the parasitic inductance is small for the general overcurrent with a small current rise rate, which can easily cause the misoperation of short-circuit protection.

[0005] Therefore, there is an urgent need for a new technical solution for protecting the power device IGBT. SUMMARY

[0006] In view of the above analysis, the embodiments of the present application aim to provide an overcurrent protection method for a high-power IGBT to solve the problems of reduced service life and misoperation of the high-power IGBT protection in the prior art.

[0007] The embodiments of the present application provide an overcurrent protection method for a high-power IGBT, which comprises:

[0008] detecting a turn-on and turn-off signal of the high-power IGBT;

[0009] collecting a collector voltage of the high-power IGBT, judging whether the collector voltage is greater than a voltage threshold value, and obtaining a voltage judgment result;

[0010] collecting a collector current of the high-power IGBT, judging whether the collector current is greater than a current threshold value, and obtaining a current judgment result;

[0011] determining whether to perform overcurrent protection on the high-power IGBT according to the turn-on and turn-off signal, the voltage judgment result and the current judgment result; if yes, performing overcurrent protection by slowly pulling down the gate voltage through a soft turn-off circuit.

[0012] Based on the further improvement of the above method, the collecting the collector voltage of the high-power IGBT comprises: collecting the collector voltage of the high-power IGBT by a collector voltage detection circuit; wherein,

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

[0014] The negative electrode of the second diode D2 is connected to the collector of the high-power IGBT, the positive electrode of the second diode D2 is connected to one end of the capacitor C1 and one end of the second resistor R2 at the same time; the other end of the second resistor R2 is connected to the positive electrode power supply VCC, and the other end of the capacitor C1 is connected to the negative electrode power supply VEE; the collector voltage is output by the positive electrode 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 a second comparator, judges whether the collector voltage is greater than a voltage threshold in the second comparator, and obtains a voltage judgment result;

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

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

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

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

[0020] Based on the further improvement of the above method, the collecting the collector current of the high-power IGBT comprises: collecting the collector current of the high-power IGBT by a collector current detection circuit; wherein,

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

[0022] The detection end of the current Hall L is connected to the collector of the high-power IGBT for collecting the collector current; the output end 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 end 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 determines whether the collector current is greater than the current threshold in the first comparator to obtain a current determination result.

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

[0025] Based on the further improvement of the above method, the determination of whether to perform overcurrent protection on the high-power IGBT according to the turn-on and turn-off signal, the voltage determination result and the current determination result comprises:

[0026] If the turn-on and turn-off signal is a turn-on signal, the voltage determination result is that the collector voltage is greater than the voltage threshold, and the current determination result is that the collector current is greater than the current threshold, an overcurrent protection control signal is outputted to perform overcurrent protection on the high-power IGBT.

[0027] Based on the further improvement of the above method, the soft turn-off circuit comprises a third MOS tube Q3 and a third resistor R3; the gate of the third MOS tube Q3 is used for receiving a control signal of whether to perform overcurrent protection on the high-power IGBT;

[0028] The source of the third MOS tube Q3 is connected to the negative power supply VEE, the drain of the third MOS tube Q3 is connected to one end of the third resistor R3, and the other end of the third resistor R3 is connected to the gate of the high-power IGBT, which is used for reducing the gate voltage of the high-power IGBT and turning off the high-power IGBT.

[0029] Based on the further improvement of the above method, the turn-on and turn-off signal, the voltage determination result and the current determination result are received by a logic circuit, and it is determined whether to perform overcurrent protection on the high-power IGBT; wherein,

[0030] The logic circuit comprises a NOT gate G INV1 , a first AND gate G AND1 and a second AND gate G AND2 .

[0031] The input end of the NOT gate G INV1 receives the turn-on and turn-off signal generated by the PWM control generator, the output end of the NOT gate G INV1 is connected to one input end of the first AND gate G AND1 , the other input end of the first AND gate G AND1 is used for receiving the voltage determination result, and the output end of the first AND gate G AND1 is connected to one input end of the second AND gate G AND2 ; the other input end of the second AND gate G AND2 is used for receiving the current determination result, and the output end of the second AND gate G AND2The output end generates a control signal of whether overcurrent protection is performed on the high-power IGBT.

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

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

[0034] Based on the further improvement of the above method, the turn-on and turn-off signal controls the turn-on and turn-off of the high-power IGBT through a push-pull amplification circuit; the push-pull amplification circuit comprises a first MOS tube Q1, a second MOS tube Q2, a turn-on resistor Ron and a turn-off resistor Roff.

[0035] The source of the first MOS tube Q1 is connected to a positive power supply VCC, and the source of the second MOS tube Q2 is connected to a negative power supply VEE; the gates of the first MOS tube Q1 and the second MOS tube Q2 are simultaneously connected to the PWM control generator, for receiving the turn-on and turn-off signal.

[0036] The drain of the first MOS tube Q1 is connected to one end of the turn-on resistor Ron, and the drain of the second MOS tube Q2 is connected to one end of the turn-off resistor Roff; the other end of the turn-on resistor Ron and one end of the turn-off resistor Roff are simultaneously connected to the gate of the high-power IGBT, for generating a gate voltage to control the turn-on and turn-off of the high-power IGBT.

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

[0038] By detecting the turn-on and turn-off signal, the collector voltage and the collector current, and combining the preset voltage threshold and the current threshold, if it is determined that overcurrent protection is performed on the high-power IGBT, the gate voltage is slowly pulled down through the soft turn-off circuit to perform overcurrent protection, which reduces the false action of protection and improves the service life of the high-power IGBT.

[0039] In the present application, the above technical solutions can be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present application will be described in the subsequent specification, and some advantages will become apparent from the specification or be understood by implementing the present application. The purposes and other advantages of the present application can be achieved and obtained from the contents specifically pointed out in the specification and the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0040] The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the principles of the application.

[0041] Figure 1 A flowchart of a method for overcurrent protection of a high-power IGBT is provided for an embodiment of the application.

[0042] Figure 2 A structural diagram of an overcurrent protection circuit for a high-power IGBT is provided for an embodiment of the application. DETAILED DESCRIPTION

[0043] The preferred embodiments of the present application will be described in detail with reference to the drawings, in which the same reference numerals refer to the same elements throughout the several views. The drawings provided herein are for illustrative purposes only and, therefore, are not to be considered to be limiting of the application, the scope of which is to be determined with reference to the claims.

[0044] IGBT has high voltage and current handling capability, and faster switching speed, and is widely used in frequency converters, inverters, electric vehicle drive systems, power transmission and distribution systems, and other power electronic fields.

[0045] One specific embodiment of the present application discloses a method for overcurrent protection of a high-power IGBT, wherein the high-power IGBT refers to an IGBT with a rated power greater than 1KW, such as Figure 1 As shown in the figure, the overcurrent protection method comprises:

[0046] Step S1: detecting a turn-on and turn-off signal of the high-power IGBT;

[0047] Step S2: collecting a collector voltage of the high-power IGBT, determining whether the collector voltage is greater than a voltage threshold, and obtaining a voltage determination result;

[0048] Step S3: collecting a collector current of the high-power IGBT, determining whether the collector current is greater than a current threshold, and obtaining a current determination result;

[0049] Step S4: determining whether to perform overcurrent protection on the high-power IGBT according to the turn-on and turn-off signal, the voltage determination result, and the current determination result; if yes, performing overcurrent protection by slowly pulling down the gate voltage through a soft turn-off circuit.

[0050] Specifically, the high-power IGBT is turned on or off by a gate voltage connected to its gate. When turned 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, which connects the collector and the emitter, allowing current to flow through the IGBT. At this time, the IGBT is in the on state. When turned off, the gate voltage is lowered below the threshold voltage, the N-channel disappears, and the current path between the collector and the emitter is cut off, and the IGBT enters the off state.

[0051] Specifically, as shown in Figure 1 When overcurrent protection is performed on the high-power IGBT, steps S1, S2 and S3 can be executed synchronously or asynchronously. The on-off signals, voltage determination results and current determination results obtained by steps S1, S2 and S3 are transmitted to step S4, and it is determined whether to perform overcurrent protection on the high-power IGBT in step S4.

[0052] Specifically, if the high-power IGBT does not need to be protected, no protection action is taken; if it is determined that the high-power IGBT needs to be protected, the gate voltage connected to the gate of the high-power IGBT is slowly pulled down through the soft turn-off circuit, and then the high-power IGBT is turned off to prevent the high-power IGBT from being damaged.

[0053] Specifically, in step S1, the on-off signal of the high-power IGBT includes two types, one is an on signal for the high-power IGBT to be in the on state, and the other is an off signal for the high-power IGBT to be in the off state.

[0054] Specifically, in step S2, the voltage threshold is a pre-set safety 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 pre-set safety 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, it is determined whether to perform overcurrent protection on the high-power IGBT according to the on-off signal, voltage determination result and current determination result obtained by steps 1, 2 and 3.

[0057] Preferably, the determination of whether to perform overcurrent protection on the high-power IGBT according to the on-off signal, voltage determination result and current determination result comprises:

[0058] If the conduction-off signal is a conduction signal, the voltage determination result is that the collector voltage is greater than the voltage threshold, and the current determination result is that the collector current is greater than the current threshold, an overcurrent protection control signal is output to perform overcurrent protection on the high-power IGBT.

[0059] Specifically, when the conduction-off signal is a conduction signal, the voltage determination result is that the collector voltage is greater than the voltage threshold, and the current determination result is that the collector current is greater than the current threshold, it can be determined that the high-power IGBT is in short-circuit overcurrent, and overcurrent protection needs to be performed on the high-power IGBT. The gate voltage of the high-power IGBT is slowly pulled down by the soft-off circuit to perform overcurrent protection.

[0060] Preferably, the collector voltage of the high-power IGBT is collected by a collector voltage detection circuit.

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

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

[0063] Specifically, as shown in Figure 2 The collector voltage of the high-power IGBT is collected by the collector voltage detection circuit. The second diode D2 is turned on under the action of the positive electrode power supply VCC. When the collector voltage of the high-power IGBT rises, the positive electrode voltage of the second diode D2 is greater than the negative electrode voltage by one conduction voltage of the second diode, and the positive electrode voltage of the second diode D2 rises synchronously. At this time, the positive electrode voltage of the second diode D2 can be used to represent the collector voltage of the high-power IGBT, and the positive electrode voltage of the second diode D2 is changed by charging and discharging the capacitor C1.

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

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

[0066] Specifically, as shown in Figure 2As shown, the positive voltage of the second diode D2 is connected to the positive input terminal of the second comparator U2, the voltage threshold is set to the reference voltage Vref2 of the second comparator U2, and is 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 a 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 cathode of the third diode D3 is connected to the positive power supply VCC, and the anode of the third diode D3 is connected to the anode of the second diode D2;

[0069] An anode of the fourth diode D4 is connected to the negative power source VEE, and a cathode of the fourth diode D4 is connected to the anode 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 and a glitch signal is generated, the third diode D3 and the fourth diode D4 can maintain the positive electrode voltage of the second diode D2 within the range of the positive power supply VCC and the negative power supply VEE, thereby protecting the collector voltage detection circuit.

[0071] Preferably, said collecting the collector current of the high-power IGBT comprises: collecting 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 L and a first resistor R1;

[0073] The detection end of the current Hall L is connected to the collector of the high-power IGBT for collecting the collector current; the output end 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 end 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 collected through the collector current detection circuit, the detection end of the current Hall L is connected to the collector of the high-power IGBT for detecting the collector current of the high-power IGBT, and the first resistor R1 is used to sample the collected 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 a current determination 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, as shown in the figure, Figure 2 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, and the negative input terminal of the first comparator is used to set the current threshold as the reference voltage Vref1 of the first comparator. After the first comparator U1 compares the collector current with the current threshold, the current judgment result is obtained and output through the output terminal of the first comparator U1.

[0078] Preferably, as shown in the figure, Figure 2 the soft turn-off circuit comprises a third MOS tube Q3 and a third resistor R3; the gate of the third MOS tube 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 MOS tube Q3 is connected to the negative power supply VEE, the drain of the third MOS tube Q3 is connected to one end of the third resistor R3, and 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 off the high-power IGBT.

[0080] Specifically, the gate of the third MOS tube Q3 is used to receive a control signal for performing overcurrent protection on the high-power IGBT and a control signal for not performing overcurrent protection on the high-power IGBT. When the gate of the third MOS tube Q3 receives the control signal for performing overcurrent protection on the high-power IGBT, the third MOS tube Q3 is turned on. After the third MOS tube Q3 is turned on, the gate voltage connected to the gate of the high-power IGBT through the third resistor R3 is divided, so that the gate voltage of the high-power IGBT slowly decreases. When the gate voltage decreases to a certain extent, the high-power IGBT will be turned off, thereby realizing overcurrent protection of the high-power IGBT.

[0081] Preferably, the logic circuit receives the turn-on and turn-off signal, the voltage judgment result and the current judgment result, and determines whether to perform overcurrent protection on the high-power IGBT; wherein,

[0082] The logic circuit comprises a NOT gate G INV1 , a first AND gate G AND1 and a second AND gate G AND2 .

[0083] The input terminal of the NOT gate G INV1 receives the turn-on and turn-off signal generated by the PWM control generator, the output terminal of the NOT gate G INV1 is connected to the first AND gate G AND1one input end of the first AND gate G AND1 another input end of the first AND gate G AND1 is connected to one input end of the second AND gate G AND2 another input end of the second AND gate G AND2 is used for receiving the current judgment result, and an output end of the second AND gate G AND2 generates a control signal for whether to perform overcurrent protection on the high-power IGBT.

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

[0085] Specifically, as shown in Figure 2 , the non-inverter G INV1 , the first AND gate G AND1 and the second AND gate G AND2 included in the logic circuit perform logical judgment on the turn-on and turn-off signal, the voltage judgment result and the current judgment result, and then obtain a result for whether to perform overcurrent protection on the high-power IGBT, and finally output the result to the soft turn-off circuit through the second AND gate G AND2 , and then control the turn-on and turn-off states of the high-power IGBT.

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

[0087] Preferably, the turn-on and turn-off signal controls the turn-on and turn-off of the high-power IGBT through the push-pull amplification circuit; the push-pull amplification circuit includes a first MOS tube Q1, a second MOS tube Q2, a turn-on resistor Ron and a turn-off resistor Roff;

[0088] A source of the first MOS tube Q1 is connected to a positive power supply VCC, and a source of the second MOS tube Q2 is connected to a negative power supply VEE; a gate of the first MOS tube Q1 and a gate of the second MOS tube Q2 are connected to the PWM control generator at the same time, for receiving the turn-on and turn-off signal;

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

[0090] Specifically, as shown in Figure 2 the push-pull amplifier circuit, when the PWM control generator generates a high-level signal, the second MOS Q2 is turned on, and the first MOS is turned off, at this time, the gate voltage connected to the gate of the high-power IGBT is pulled to the negative power supply VEE, and the high-power IGBT is in an off state; when the PWM control generator generates a low-level signal, the first MOS Q1 is turned on, and the second MOS is turned off, at this time, the gate voltage connected to the gate of the high-power IGBT is pulled to the positive power supply VCC, and the high-power IGBT is in an on state.

[0091] Specifically, the on-resistance Ron and the off-resistance Roff can be variable resistors, so as to adjust the switching speed of the high-power IGBT.

[0092] Specifically, as shown in Figure 2 the push-pull amplifier circuit, when the PWM control generator generates a high-level signal, the second MOS Q2 is turned on, and the first MOS is turned off, at this time, the gate voltage connected to the gate of the high-power IGBT is pulled to the negative power supply VEE, and the high-power IGBT is in an off state; when the PWM control generator generates a low-level signal, the first MOS Q1 is turned on, and the second MOS is turned off, at this time, the gate voltage connected to the gate of the high-power IGBT is pulled to the positive power supply VCC, and the high-power IGBT is in an on state.

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

[0094] It is worth noting that when the PWM control generator generates a high-level signal, the high-power IGBT will be in an off state through the action of the push-pull amplifier circuit, at this time, no matter what the voltage judgment result is, and no matter what the current judgment result is, the logic circuit will output a low level through the second AND gate G AND2 to make the soft-off circuit not act.

[0095] When the PWM occurrence controller generates a low level signal, the first MOS tube Q1 is turned on, the high-power IGBT is in an open state, and the non-gate G INV1 outputs a high level signal, and when the collector voltage detection circuit detects an overcurrent signal and outputs a high level signal, the first AND gate G AND1 outputs a high level signal, and when the collector current detection circuit detects an overcurrent signal and outputs a high level signal in this case, the second AND gate G AND2 outputs a high level signal, the third MOS tube Q3 is turned on, and the soft turn-off circuit is actuated, so that the high-power IGBT is in a turn-off state.

[0096] Compared with the prior art, the overcurrent protection method for the high-power IGBT provided by the embodiment of the present application detects the turn-on and turn-off signals, the collector voltage and the collector current, combines the preset voltage threshold and the current threshold, and if it is determined to perform overcurrent protection on the high-power IGBT, the gate voltage is slowly pulled down through the soft turn-off circuit to perform overcurrent protection, which reduces the false action of protection and improves the service life of the high-power IGBT.

[0097] Those skilled in the art can understand that all or part of the processes of the above-mentioned embodiment methods can be completed by a computer program instructing related hardware, and the program can be stored in a computer readable storage medium, wherein the computer readable storage medium is a disk, an optical disc, a read-only memory or a random access memory, etc.

[0098] The above is only a preferred specific implementation of the present application, but the protection scope of the present application is not limited to this. Any changes or replacements that can be easily thought of by those skilled in the art within the technical scope disclosed by the present application should be covered within the protection scope of the present application.

Claims

1. A method for overcurrent protection of a high power IGBT, characterized by, The overcurrent protection method comprises: Detecting a turn-on and turn-off signal of the high-power IGBT; Collecting a collector voltage of the high-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 high-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 high-power IGBT according to the turn-on and turn-off signal, the voltage judgment result and the current judgment result; if yes, performing overcurrent protection by slowly pulling down a gate voltage through a soft turn-off circuit.

2. The overcurrent protection method of claim 1, wherein, The collector voltage of the high-power IGBT is collected by a collector voltage detection circuit; wherein, The collector voltage detection circuit comprises a second resistor R2, a capacitor C1 and a second diode D2; The negative electrode of the second diode D2 is connected to the collector of the high-power IGBT, the positive electrode of the second diode D2 is connected to one end of the capacitor C1 and one end of the second resistor R2 at the same time, the other end of the second resistor R2 is connected to the positive electrode power supply VCC, and the other end of the capacitor C1 is connected to the negative electrode power supply VEE; the collector voltage is output from the positive electrode of the second diode D2.

3. The overcurrent protection method of claim 2, wherein, The collector voltage detection circuit transmits the collected collector voltage to a second comparator, and judges whether the collector voltage is greater than the voltage threshold value in the second comparator to obtain the voltage judgment result; The positive electrode input end of the second comparator receives the collector voltage, the negative electrode input end of the second comparator receives the voltage threshold value, and the output end of the second comparator outputs the voltage judgment result.

4. The overcurrent protection method of claim 2, wherein, The collector voltage detection circuit further comprises a third diode D3 and a fourth diode D4; The negative electrode of the third diode D3 is connected to the positive electrode power supply VCC, and the positive electrode of the third diode D3 is connected to the positive electrode of the second diode D2; The positive electrode of the fourth diode D4 is connected to the negative electrode power supply VEE, and the negative electrode of the fourth diode D4 is connected to the positive electrode of the second diode D2.

5. The overcurrent protection method of claim 1, wherein, The collector current of the high-power IGBT is collected by a collector current detection circuit; wherein, The collector current detection circuit comprises a current Hall L and a first resistor R1; The detection end of the current Hall L is connected to the collector of the high-power IGBT for collecting the collector current; the output end 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 end of the current Hall L outputs the collector current.

6. The overcurrent protection method of claim 5, wherein, The collector current detection circuit transmits the detected collector current to a first comparator, and judges whether the collector current is greater than the current threshold value in the first comparator to obtain the current judgment result; The positive electrode input end of the first comparator receives the collector current, the negative electrode input end of the first comparator receives the current threshold value, and the output end of the first comparator outputs the current judgment result.

7. The overcurrent protection method of claim 1, wherein, The determination whether to perform overcurrent protection on the high-power IGBT according to the turn-on and turn-off signal, the voltage judgment result and the current judgment result comprises: If the conduction-off signal is a conduction signal, the voltage determination result is that the collector voltage is greater than the voltage threshold, and the current determination result is that the collector current is greater than the current threshold, an overcurrent protection control signal is output to perform overcurrent protection on the high-power IGBT.

8. The overcurrent protection method according to any one of claims 1 to 7, characterized in that, The soft-off circuit includes a third MOS tube Q3 and a third resistor R3; a gate of the third MOS tube Q3 is configured to receive a control signal for determining whether to perform overcurrent protection on the high-power IGBT; A source of the third MOS tube Q3 is connected to a negative power supply VEE, a drain of the third MOS tube Q3 is connected to one end of the third resistor R3, and the other end of the third resistor R3 is connected to a gate of the high-power IGBT, for reducing a gate voltage of the high-power IGBT and turning off the high-power IGBT.

9. The overcurrent protection method of claim 7, wherein, The logic circuit is configured to receive the conduction-off signal, the voltage determination result, and the current determination result, and determine whether to perform overcurrent protection on the high-power IGBT. The logic circuit comprises a NOT gate G INV1 , a first AND gate G AND1 , and a second AND gate G AND2 ; The input end of the NOT gate G INV1 receives the on-off signal generated by the PWM control generator, the output end of the NOT gate G INV1 is connected with one input end of the first AND gate G AND1 , the other input end of the first AND gate G AND1 is used for receiving the voltage judgment result, the output end of the first AND gate G AND1 is connected with one input end of the second AND gate G AND2 , the other input end of the second AND gate G AND2 is used for receiving the current judgment result, and the output end of the second AND gate G AND2 generates the control signal of whether to perform overcurrent protection on the high-power IGBT. The PWM control generator is configured to generate the conduction-off signal of the high-power IGBT; when the conduction-off signal is a high-level signal, the high-power IGBT is in an off state; and when the conduction-off signal is a low-level signal, the high-power IGBT is in a conduction state.

10. The overcurrent protection method of claim 9, wherein, The conduction-off signal controls the conduction and the off of the high-power IGBT through the push-pull amplification circuit; the push-pull amplification circuit includes a first MOS tube Q1, a second MOS tube Q2, a conduction resistor Ron, and an off resistor Roff. A source of the first MOS tube Q1 is connected to a positive power supply VCC, and a source of the second MOS tube Q2 is connected to the negative power supply VEE; gates of the first MOS tube Q1 and the second MOS tube Q2 are simultaneously connected to the PWM control generator, for receiving the conduction-off signal. A drain of the first MOS tube Q1 is connected to one end of the conduction resistor Ron, and a drain of the second MOS tube Q2 is connected to one end of the off resistor Roff; the other end of the conduction resistor Ron and the one end of the off resistor Roff are simultaneously connected to the gate of the high-power IGBT, for generating a gate voltage to control the conduction and the off of the high-power IGBT.

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