CN108592343B

CN108592343B - IGBT tube gate resistance adjusting circuit and air conditioner

Info

Publication number: CN108592343B
Application number: CN201810268458.3A
Authority: CN
Inventors: 江雪晨; 冯宇翔; 张土明
Original assignee: Midea Group Co Ltd; GD Midea Air Conditioning Equipment Co Ltd
Current assignee: Meiken Semiconductor Technology Co ltd
Priority date: 2018-03-28
Filing date: 2018-03-28
Publication date: 2020-07-03
Anticipated expiration: 2038-03-28
Also published as: CN108592343A

Abstract

The invention discloses an IGBT (insulated gate bipolar transistor) gate resistance adjusting circuit and an air conditioner, wherein the IGBT gate resistance adjusting circuit comprises a turn-off signal input end, a turn-on signal input end, a voltage sampling circuit, a control circuit and a driving circuit; the voltage sampling circuit is used for sampling the working current of the IGBT tube, converting the sampled working current into a voltage signal and outputting the voltage signal to the control circuit; the control circuit is used for comparing the received voltage signal with a preset voltage threshold value and outputting a corresponding control signal to the driving circuit according to a comparison result and signals of the turn-off signal input end and the turn-on signal input end; and the driving circuit is used for adjusting the gate resistance of the IGBT tube according to the received control signal when the voltage signal is greater than the preset voltage threshold value, so that the IGBT tube executes a soft turn-off process. The invention effectively inhibits the overvoltage generated when the IGBT tube is short-circuited.

Description

IGBT tube gate resistance adjusting circuit and air conditioner

Technical Field

The invention relates to the technical field of electronics, in particular to an IGBT tube gate resistance adjusting circuit and an air conditioner.

Background

Because the IGBT tube is in a desaturation area when in short circuit, the overcurrent of the IGBT tube during short circuit depends on the voltage Uge between a gate electrode and an emitter of the IGBT tube, and if the Uge can be controlled when the IGBT tube is switched off, the overcurrent of the IGBT tube during short circuit can be well controlled. For the characteristics, in the prior art, a measure of increasing the gate off resistance of the IGBT is usually adopted to suppress the overcurrent when the IGBT is short-circuited, that is, a measure of increasing the gate off resistance of the IGBT is also adopted to suppress the overvoltage generated when the IGBT is short-circuited.

Disclosure of Invention

The invention mainly aims to provide an IGBT tube gate resistance regulating circuit, which aims to effectively inhibit overvoltage generated when an IGBT tube is short-circuited without influencing output power of the IGBT tube.

In order to achieve the above object, the present invention provides an IGBT gate resistance adjusting circuit, which includes a turn-off signal input terminal, a turn-on signal input terminal, a voltage sampling circuit, a control circuit, and a driving circuit; wherein:

the turn-off signal input end is used for inputting a turn-off signal for controlling the turn-off of the IGBT tube;

the turn-on signal input end is used for inputting a turn-on signal for controlling the turn-on of the IGBT tube;

the voltage sampling circuit is used for sampling the working current of the IGBT tube, converting the sampled working current into a voltage signal and outputting the voltage signal to the control circuit;

the control circuit is used for comparing the received voltage signal with a preset voltage threshold value and outputting a corresponding control signal to the drive circuit according to a comparison result, the turn-off signal and the turn-on signal so as to control the work of the drive circuit;

and the driving circuit is used for adjusting the gate resistance of the IGBT tube according to the received control signal when the voltage signal is greater than a preset voltage threshold value, so that the IGBT tube executes a soft turn-off process.

Preferably, the sampling input end of the voltage sampling circuit is connected with the current output end of the IGBT tube, the sampling output end of the voltage sampling circuit is connected with the first control input end of the control circuit, the second control input end of the control circuit is connected with the turn-off signal input end, the third control input end of the control circuit is connected with the turn-on signal input end, the control output end of the control circuit is connected with the driving input end of the driving circuit, and the driving output end of the driving circuit is connected with the gate pole of the IGBT tube.

Preferably, the control circuit comprises a voltage comparator, a preset voltage threshold input end, a diode, a working voltage input end, a pull-up resistor, an RC circuit unit, an or gate, a first not gate, a second not gate, a first and gate and a second and gate; wherein:

the non-inverting input end of the voltage comparator is connected with the sampling output end of the voltage sampling circuit, the inverting input end of the voltage comparator is connected with the preset voltage threshold input end, the output end of the voltage comparator is respectively connected with the cathode of the diode, the first input end of the first AND gate and the input end of the first NOT gate, the anode of the diode is respectively connected with the first end of the pull-up resistor, the first end of the RC circuit unit and the first input end of the OR gate, the second end of the pull-up resistor is connected with the working voltage input end, and the second end of the RC circuit unit is grounded; a second input end of the or gate is a second control input end of the control circuit, a second input end of the or gate is connected with the turn-off signal input end, and an output end of the or gate is respectively connected with an input end of the second not gate and a second driving input end of the driving circuit; the output end of the second NOT gate is connected with the second input end of the first AND gate, and the output end of the first AND gate is connected with the first driving input end of the driving circuit; the output end of the first NOT gate is connected with the first input end of the second AND gate, the second input end of the second AND gate is the third control input end of the control circuit, the second input end of the second AND gate is connected with the opening signal input end, and the output end of the second AND gate is connected with the third driving input end of the driving circuit.

Preferably, the RC circuit unit includes a first resistor and a first capacitor; wherein:

the first end of the first resistor is connected with the anode of the diode, and the second end of the first resistor is grounded through the first capacitor.

Preferably, the driving circuit comprises a first switching tube driving circuit unit, a second switching tube driving circuit unit, a third switching tube driving circuit unit, a first gate resistance, a second gate resistance and a third gate resistance; wherein:

the control end of the first switching tube driving circuit unit is a first driving input end of the driving circuit, the control end of the first switching tube driving circuit unit is connected with the output end of the first AND gate, and the driving output end of the first switching tube driving circuit unit is connected with the gate of the IGBT tube through the first gate resistor;

the control end of the second switching tube driving circuit unit is a second driving input end of the driving circuit, the control end of the second switching tube driving circuit unit is connected with the output end of the OR gate, and the driving output end of the second switching tube driving circuit unit is connected with the gate pole of the IGBT tube through the second gate pole resistor;

the control end of the third switching tube driving circuit unit is a third driving input end of the driving circuit, the control end of the third switching tube driving circuit unit is connected with the output end of the second and gate, and the driving output end of the third switching tube driving circuit unit is connected with the gate of the IGBT tube through the third gate resistor.

Preferably, the first switching tube driving circuit unit includes a first NMOS tube and a first driving power supply input end; wherein:

the grid electrode of the first NMOS tube is connected with the output end of the first AND gate, the drain electrode of the first NMOS tube is connected with the gate electrode of the IGBT tube through the first gate electrode resistor, and the source electrode of the first NMOS tube is connected with the input end of the first driving power supply.

Preferably, the second switching tube driving circuit unit includes a second NMOS tube and a second driving power supply input end; wherein:

the grid electrode of the second NMOS tube is connected with the output end of the OR gate, the drain electrode of the second NMOS tube is connected with the gate electrode of the IGBT tube through the second gate resistance, and the source electrode of the second NMOS tube is connected with the input end of the second driving power supply.

Preferably, the third switching tube driving circuit unit includes a third NMOS tube and a third driving power supply input end; wherein:

the grid electrode of the third NMOS tube is connected with the output end of the second AND gate, the drain electrode of the third NMOS tube is connected with the gate electrode of the IGBT tube through the third gate electrode resistor, and the source electrode of the third NMOS tube is connected with the input end of the third driving power supply.

Preferably, the first gate resistor has a larger resistance value than the second gate resistor.

In addition, in order to achieve the above object, the present invention further provides an air conditioner, which includes the IGBT gate resistance adjusting circuit as described above.

The invention provides an IGBT (insulated gate bipolar transistor) gate resistance regulating circuit, which comprises a turn-off signal input end, a turn-on signal input end, a voltage sampling circuit, a control circuit and a drive circuit, wherein the turn-off signal input end is connected with the turn-on signal input end; the turn-off signal input end is used for inputting a turn-off signal for controlling the turn-off of the IGBT tube; the turn-on signal input end is used for inputting a turn-on signal for controlling the turn-on of the IGBT tube; the voltage sampling circuit is used for sampling the working current of the IGBT tube, converting the sampled working current into a voltage signal and outputting the voltage signal to the control circuit; the control circuit is used for comparing the received voltage signal with a preset voltage threshold value and outputting a corresponding control signal to the drive circuit according to a comparison result, the turn-off signal and the turn-on signal so as to control the work of the drive circuit; and the driving circuit is used for adjusting the gate resistance of the IGBT tube according to the received control signal when the voltage signal is greater than a preset voltage threshold value, so that the IGBT tube executes a soft turn-off process. According to the IGBT tube gate resistance adjusting circuit, when the voltage signal sampled by the voltage sampling circuit is larger than the preset voltage threshold value, the driving circuit can adjust the gate resistance of the IGBT tube according to the received control signal output by the control circuit, so that the IGBT tube executes a soft turn-off process, the overvoltage generated when the IGBT tube is short-circuited is effectively inhibited, and the reliability of the IGBT tube is improved; meanwhile, the IGBT tube gate resistance adjusting circuit also has the advantage of not influencing the output power of the IGBT tube during normal operation.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.

Fig. 1 is a functional module schematic diagram of an embodiment of an IGBT gate resistance adjusting circuit according to the present invention;

FIG. 2 is a schematic structural diagram of an embodiment of a gate resistance adjusting circuit of an IGBT according to the present invention;

fig. 3 is a schematic diagram illustrating operating mode switching of an IGBT according to an embodiment of the IGBT gate resistance adjusting circuit of the present invention.

The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.

Detailed Description

It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The invention provides a gate resistance regulating circuit of an IGBT (insulated gate bipolar transistor), which is used for effectively inhibiting overvoltage generated when the IGBT is short-circuited without influencing the output power of the IGBT so as to improve the reliability of the IGBT.

Fig. 1 is a functional block schematic diagram of an embodiment of an IGBT gate resistance adjusting circuit according to the present invention, and referring to fig. 1, IN an embodiment, the IGBT gate resistance adjusting circuit includes an off signal input terminal IN1, an on signal input terminal IN2, a voltage sampling circuit 101, a control circuit 102, and a driving circuit 103.

Specifically, the turn-off signal input terminal IN1 is used for inputting a turn-off signal for controlling the turn-off of the IGBT 200;

the turn-on signal input end IN2 is used for inputting a turn-on signal for controlling the turn-on of the IGBT tube 200;

the voltage sampling circuit 101 is configured to sample a working current of the IGBT 200, convert the sampled working current into a voltage signal, and output the voltage signal to the control circuit 102;

the control circuit 102 is configured to compare the received voltage signal with a preset voltage threshold, and output a corresponding control signal to the driving circuit 103 according to a comparison result, the turn-off signal and the turn-on signal, so as to control the operation of the driving circuit 103;

the driving circuit 103 is configured to adjust a gate resistance of the IGBT tube 200 according to the received control signal output by the control circuit 102 when the voltage signal is greater than a preset voltage threshold, so that the IGBT tube 200 performs a soft turn-off process.

The sampling input end of the voltage sampling circuit 101 is connected with the current output end of the IGBT tube 200, the sampling output end of the voltage sampling circuit 101 is connected with the first control input end a of the control circuit 102, the second control input end B of the control circuit 102 is connected with the turn-off signal input end IN1, the third control input end C of the control circuit 102 is connected with the turn-on signal input end IN2, the control output end of the control circuit 102 is connected with the driving input end of the driving circuit 103, and the driving output end of the driving circuit 103 is connected with the gate of the IGBT tube 200.

Fig. 2 is a schematic structural diagram of an embodiment of a gate resistance adjusting circuit of an IGBT according to the present invention, and referring to fig. 1 and fig. 2 together, in this embodiment, the control circuit 102 includes a voltage comparator U1, a preset voltage threshold input terminal E, a diode D1, an operating voltage input terminal VCC0, a pull-up resistor R0, an RC circuit unit 1021, an or gate U2, a first not gate U3, a second not gate U4, a first and gate U5, and a second and gate U6. Specifically, a non-inverting input terminal of the voltage comparator U1 is a first control input terminal a of the control circuit 102, a non-inverting input terminal of the voltage comparator U1 is connected to a sampling output terminal of the voltage sampling circuit 101, an inverting input terminal of the voltage comparator U1 is connected to the preset voltage threshold input terminal E, an output terminal of the voltage comparator U1 is connected to a cathode of the diode D1, a first input terminal of the first and gate U5, and an input terminal of the first not gate U3, an anode of the diode D1 is connected to a first terminal of the pull-up resistor R0, a first terminal of the RC circuit unit 1021, and a first input terminal of the or gate U2, a second terminal of the pull-up resistor R0 is connected to the working voltage input terminal VCC0, and a second terminal of the RC circuit unit 1021 is grounded; a second input terminal of the or gate U2 is a second control input terminal B of the control circuit 102, a second input terminal of the or gate U2 is connected to the turn-off signal input terminal IN1, and an output terminal of the or gate U2 is respectively connected to an input terminal of the second not gate U4 and a second driving input terminal B1 of the driving circuit 103; an output end of the second not gate U4 is connected to a second input end of the first and gate U5, and an output end of the first and gate U5 is connected to the first driving input end a1 of the driving circuit 102; an output end of the first not gate U3 is connected to a first input end of the second and gate U6, a second input end of the second and gate U6 is a third control input end C of the control circuit 102, a second input end of the second and gate U6 is connected to the turn-on signal input end IN2, and an output end of the second and gate U6 is connected to a third driving input end C1 of the driving circuit 103.

In this embodiment, the RC circuit unit 1021 includes a first resistor R1 and a first capacitor C1. Specifically, a first terminal of the first resistor R1 is connected to the anode of the diode D1, and a second terminal of the first resistor R1 is connected to ground via the first capacitor C1.

In this embodiment, the driving circuit 103 includes a first switching transistor driving circuit unit 1031, a second switching transistor driving circuit unit 1032, a third switching transistor driving circuit unit 1033, a first gate resistor Roff1, a second gate resistor Roff2, and a third gate resistor Ron. Specifically, the control terminal of the first switching tube driving circuit unit 1031 is the first driving input terminal a1 of the driving circuit 103, the control terminal of the first switching tube driving circuit unit 1031 is connected to the output terminal of the first and gate U5, and the driving output terminal of the first switching tube driving circuit unit 1031 is connected to the gate G of the IGBT tube 200 through the first gate resistor Roff 1;

the control end of the second switching tube driving circuit unit 1032 is a second driving input end b1 of the driving circuit 103, the control end of the second switching tube driving circuit unit 1032 is connected to the output end of the or gate U2, and the driving output end of the second switching tube driving circuit unit 1032 is connected to the gate G of the IGBT 200 through the second gate resistor Roff 2;

the control end of the third switching tube driving circuit unit 1033 is a third driving input end c1 of the driving circuit 103, the control end of the third switching tube driving circuit unit 1033 is connected to the output end of the second and gate U6, and the driving output end of the third switching tube driving circuit unit 1033 is connected to the gate G of the IGBT 200 through the third gate resistor Ron.

In this embodiment, the first switch driving circuit unit 1031 includes a first NMOS transistor M1 and a first driving power input terminal VCC 1. Specifically, the gate of the first NMOS transistor M1 is connected to the output terminal of the first and gate U5, the drain of the first NMOS transistor M1 is connected to the gate G of the IGBT 200 via the first gate resistor Roff1, and the source of the first NMOS transistor M1 is connected to the first driving power input terminal VCC 1.

In this embodiment, the second switch driving circuit unit 1032 includes a second NMOS transistor M2 and a second driving power input terminal VCC 2. Specifically, the gate of the second NMOS transistor M2 is connected to the output terminal of the or gate U2, the drain of the second NMOS transistor M2 is connected to the gate G of the IGBT 200 through the second gate resistor Roff2, and the source of the second NMOS transistor M2 is connected to the second driving power input terminal VCC 2.

In this embodiment, the third switch driving circuit unit 1033 includes a third NMOS transistor M3 and a third driving power input terminal VCC 3. Specifically, the gate of the third NMOS transistor M3 is connected to the output terminal of the second and gate U6, the drain of the third NMOS transistor M3 is connected to the gate G of the IGBT 200 via the third gate resistor Ron, and the source of the third NMOS transistor M3 is connected to the third driving power input terminal VCC 3.

In this embodiment, the resistance of the first gate resistor Roff1 is greater than the resistance of the second gate resistor Roff 2.

It can be understood that, in this embodiment, the voltages of the first driving power input terminal VCC1, the second driving power input terminal VCC2 and the third driving power input terminal VCC3 can be set according to actual situations. Preferably, in this embodiment, the voltage of the first driving power input terminal VCC1 is 0V, the voltage of the second driving power input terminal VCC2 is-15V, and the voltage of the third driving power input terminal VCC3 is + 15V.

In addition, in order to simplify the circuit structure and reduce the volume of the driving device of the IGBT 200 in the present embodiment, the IGBT gate resistance adjusting circuit of the present embodiment uses field effect transistors (i.e., the first NMOS transistor M1, the second NMOS transistor M2, and the third NMOS transistor M3) to transmit an on signal and an off signal to the gate of the IGBT 200.

The operating principle of the IGBT gate resistance adjusting circuit of this embodiment is described as follows: the voltage sampling circuit 101 samples the working current of the IGBT 200 and converts the sampled working current into a voltage signal Ur, and simultaneously outputs the voltage signal Ur to the non-inverting input terminal of the voltage comparator U1 in the control circuit 102, and the inverting input terminal of the voltage comparator U1 inputs a preset voltage threshold Uref.

If Ur < Uref, it indicates that the IGBT 200 is in a normal operating state, the voltage comparator U1 outputs a low level, and the first input terminal of the first and gate U5 is at a low level, so that the first NMOS transistor M1 is turned off; the low level signal output by the voltage comparator U1 passes through the first not gate U3 and then outputs a high level, and at this time, when the on signal input by the on signal input terminal IN2 is a high level, the output terminal of the second and gate U6 is a high level, so that the third NMOS transistor M3 is turned on. And, since the diode D1 is turned on IN a forward direction when the voltage comparator U1 outputs a low level, the output of the or gate U2 is determined by the level of the off signal input from the off signal input IN1, and the second NMOS transistor M2 is turned on when the off signal input from the off signal input IN1 is at a high level.

When ur > Uref indicates that the IGBT 200 is short-circuited, the turn-off signal input from the turn-off signal input terminal IN1 is at a low level, the voltage comparator U1 outputs a high level, the high level output from the voltage comparator U1 outputs a low level after passing through the first not gate U3, the diode D1 is turned off IN reverse due to the high level output from the voltage comparator U1, the voltage at the operating voltage input terminal VCC0 is charged to the first capacitor C1 through the pull-up resistor R0 and the first resistor R1 IN the RC circuit unit 1021, after a period of time, the first capacitor C1 is charged to a voltage recognizable as the minimum voltage of the or gate U2, however, before the first capacitor C1 is charged to a voltage recognizable as the minimum voltage of the or gate U2, the or gate U2 outputs a low level, and the low level output from the or gate U2 outputs a high level after passing through the second not gate U4, that is, the second input terminal of the first and gate U5 is at a high level, and at this time, since the voltage comparator U1 outputs a high level, the first input terminal of the first and gate U5 is also at a high level, so that the first and gate U5 outputs a high level, and the first NMOS transistor M1 is turned on, at this time, the second NMOS transistor M2 is turned off due to the or gate U2 outputting a low level, and at the same time, the third NMOS transistor M3 is turned off due to the second and gate U6 outputting a low level, at this time, the gate resistance of the IGBT transistor 200 is the first gate resistance Roff 1. When the first capacitor C1 is charged to the minimum recognizable voltage of the or gate U2, the or gate U2 outputs a high level, the high level output by the or gate U2 changes to a low level after passing through the second not gate U4, so that the first NMOS transistor M1 is turned off, at this time, the second NMOS transistor M2 is turned on due to the high level output by the or gate U2, and at the same time, the third NMOS transistor M3 is turned off due to the low level output by the second and gate U6, and at this time, the gate resistance of the IGBT 200 is the second gate resistance Roff 2.

Fig. 3 is a schematic diagram illustrating switching of an operating mode of an IGBT in an embodiment of the IGBT gate resistance adjusting circuit of the present invention, and with reference to fig. 2 and fig. 3 together, to facilitate description of the above operating principle of the embodiment, an operating mode of the IGBT 200 is defined as follows:

when the third NMOS transistor M3 is turned on and both the first NMOS transistor M1 and the second NMOS transistor M2 are turned off, the operating mode of the IGBT 200 at this time is defined as a first mode 301 (also referred to as an on mode);

when the first NMOS transistor M1 is turned on and the second NMOS transistor M2 and the third NMOS transistor M3 are both turned off, the operating mode of the IGBT transistor 200 at this time is defined as a second mode 302 (also referred to as a transition mode);

when the second NMOS transistor M2 is turned on and both the first NMOS transistor M1 and the third NMOS transistor M3 are turned off, the operating mode of the IGBT 200 at this time is defined as a third mode 303 (also referred to as a soft off mode).

When the voltage signal ur input by the non-inverting input terminal of the voltage comparator U1 is greater than the preset voltage threshold Uref, that is, when the IGBT tube 200 is short-circuited, the IGBT tube 200 is in a desaturation region, and the magnitude of the overcurrent of the IGBT tube 200 depends on the voltage Uge between the gate and the emitter of the IGBT tube 200, so that when the IGBT tube 200 is turned off, if the rate of change of the voltage Uge between the gate and the emitter of the IGBT tube 200 can be controlled, the overcurrent of the IGBT tube 200 can be well controlled, that is, the overvoltage of the IGBT tube 200 can be controlled. It can be understood that the turn-off process of the IGBT 200 is a process in which the parasitic capacitance of the IGBT 200 is discharged and reversely charged through the gate resistance of the IGBT 200, and therefore, changing the gate resistance of the IGBT 200 can control the change rate of the voltage Uge between the gate and the emitter of the IGBT 200, thereby achieving the purpose of suppressing the overvoltage generated when the IGBT 200 is short-circuited, so as to improve the reliability of the IGBT.

Specifically, in this embodiment, when the IGBT tube 200 normally operates, the IGBT tube 200 is switched between the first mode 301 and the third mode 303. It can be understood that, according to the operating characteristics of the IGBT 200, there is a dead time 304 between the first mode 301 and the third mode 303. When the voltage signal ur input to the non-inverting input terminal of the voltage comparator U1 is greater than the predetermined voltage threshold Uref (i.e. ur > Uref), that is, when the IGBT 200 is short-circuited, the operating mode of the IGBT 200 is switched from the first mode 301 (corresponding to the state where M3 is on and M1 and M3 are off) to the second mode 302 (corresponding to the state where M1 is on and M2 and M3 are off), that is, when the IGBT 200 is short-circuited, the present embodiment uses a first gate resistor Roff1 (e.g. several hundred ohms) with a relatively large resistance to turn off the IGBT 200, and after a period of time (i.e. the period of time from the start of charging the first capacitor C1 in the RC circuit unit 1021 to the minimum recognizable voltage of the or gate U2), the operating mode of the IGBT 200 is switched from the second mode 302 (corresponding to the state where M1 is on and M2 and M3 are off) to the third mode 303 (M2), a state where both M1 and M3 are off). That is, when the IGBT 200 is short-circuited, in this embodiment, the first gate resistor Roff1 (for example, several hundred ohms) with a larger resistance value is used to turn off the IGBT 200, and after a period of time, the second gate resistor Roff2 (for example, several ohms) with a smaller resistance value is used to turn off the IGBT 200. In this embodiment, the change rate of the voltage Uge between the gate and the emitter of the IGBT 200 can be controlled by switching the operating mode of the IGBT 200, so as to suppress the overvoltage generated when the IGBT is short-circuited. Specifically, when the IGBT 200 is short-circuited, the IGBT 200 is first controlled to operate in the second mode 302, the gate current of the IGBT 200 is slowly decreased to a certain lower current value Ic1, and then the IGBT 200 is controlled to operate in the third mode 303, and the gate current of the IGBT 200 is decreased from the lower current value Ic1 to 0, so that the soft turn-off process of the IGBT 200 is realized (i.e., the rate of change of the voltage Uge between the gate and the emitter of the IGBT 200 is controlled), the overvoltage generated when the IGBT 200 is short-circuited is suppressed, and the reliability of the IGBT 200 is improved. That is, in the present embodiment, the second mode 302 functions only when the IGBT tube 200 is short-circuited.

In summary, when the IGBT 200 operates normally, the IGBT 200 switches between the first mode 301 and the third mode 303; when the IGBT 200 is short-circuited (that is, ur > Uref), the operating mode of the IGBT 200 is switched from the first mode 301 to the second mode 302, and after a period of time (also referred to as the waiting time of the second mode 302), the operating mode is switched from the second mode 302 to the third mode 303, so that the soft shutdown of the IGBT 200 is realized.

It should be noted that the duration of the waiting time in the second mode 302 and the resistance of the first gate resistor Roff1 are preferably selected such that the voltage Uge between the gate and the emitter of the IGBT tube 200 when switching to the third mode 303 is greater than or equal to the rated threshold voltage of the IGBT tube 200, and the operating current Ic of the IGBT tube 200 is smaller than 2 times the rated current of the IGBT tube 200, so that the total short-circuit time of the IGBT tube 200 does not burn the IGBT tube 200.

It can be understood that, when the IGBT 200 is short-circuited, the time period from the beginning of charging the first capacitor C1 in the RC circuit unit 1021 to the time period from charging the first capacitor C1 to the minimum recognizable voltage of the or gate U2 is the waiting time of the second mode 302, and the charging time constant of the first capacitor C1 can be adjusted according to actual requirements by changing the resistance value of the first resistor R1 and the capacitance of the first capacitor C1.

In the IGBT gate resistance adjusting circuit of this embodiment, when the voltage signal Ur sampled by the voltage sampling circuit 101 is greater than the preset voltage threshold Uref (that is, when the IGBT 200 is short-circuited), the driving circuit 103 can adjust the gate resistance of the IGBT 200 according to the received control signal output by the control circuit 102, that is, in this embodiment, the gate resistance of the IGBT 200 can be automatically changed when the IGBT 200 is short-circuited, so that the IGBT 200 is soft-turned off, the overvoltage generated when the IGBT 200 is short-circuited is effectively suppressed, the IGBT 200 is protected from being damaged, and the reliability of the IGBT 200 is improved; moreover, when the IGBT 200 is short-circuited, the IGBT gate resistance adjusting circuit of this embodiment automatically controls the IGBT 200 to switch to the soft turn-off mode through a simple logic circuit (i.e., the IGBT is switched from the first mode 301 to the second mode 302, and then is switched from the second mode 302 to the third mode 303), which greatly shortens the protection response time of the IGBT 200 compared with the conventional software implementation manner; in addition, in the present embodiment, the field effect transistor (i.e., the first NMOS transistor M1, the second NMOS transistor M2, and the third NMOS transistor M3) is used to transmit the turn-on signal and the turn-off signal to the gate of the IGBT 200, so that compared with the prior art that the IGBT is driven by using the triode power amplifier circuit, the circuit structure is greatly simplified, and the area of the circuit board is saved; meanwhile, the gate resistance adjusting circuit of the IGBT of this embodiment also has the advantage of not affecting the output power of the IGBT 200 during normal operation.

The invention further provides an air conditioner, which comprises the IGBT tube gate resistance adjusting circuit, and the structure and the working principle of the IGBT tube gate resistance adjusting circuit can refer to the embodiment and are not repeated herein. Therefore, the air conditioner has all the beneficial effects of the IGBT gate resistance adjusting circuit.

The above description is only a preferred embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes, which are made by using the contents of the present specification and the accompanying drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims

1. The IGBT tube gate resistance adjusting circuit is characterized by comprising a turn-off signal input end, a turn-on signal input end, a voltage sampling circuit, a control circuit and a driving circuit; wherein:

the driving circuit is used for adjusting the gate resistance of the IGBT tube according to the received control signal when the voltage signal is greater than a preset voltage threshold value so as to enable the IGBT tube to execute a soft turn-off process;

the control circuit comprises a voltage comparator, a preset voltage threshold input end, a diode, a working voltage input end, a pull-up resistor, an RC circuit unit, an OR gate, a first NOT gate, a second NOT gate, a first AND gate and a second AND gate; wherein:

2. The gate resistance adjusting circuit of the IGBT tube according to claim 1, wherein a sampling input terminal of the voltage sampling circuit is connected to a current output terminal of the IGBT tube, a sampling output terminal of the voltage sampling circuit is connected to a first control input terminal of the control circuit, a second control input terminal of the control circuit is connected to the turn-off signal input terminal, a third control input terminal of the control circuit is connected to the turn-on signal input terminal, a control output terminal of the control circuit is connected to the driving input terminal of the driving circuit, and a driving output terminal of the driving circuit is connected to the gate of the IGBT tube.

3. The IGBT gate resistance regulating circuit of claim 2, wherein the RC circuit unit comprises a first resistor and a first capacitor; wherein:

4. The IGBT gate resistance regulating circuit according to claim 3, wherein the driving circuit comprises a first switch tube driving circuit unit, a second switch tube driving circuit unit, a third switch tube driving circuit unit, a first gate resistance, a second gate resistance and a third gate resistance; wherein:

5. The IGBT gate resistance regulating circuit according to claim 4, wherein the first switch tube driving circuit unit comprises a first NMOS tube and a first driving power supply input end; wherein:

6. The IGBT gate resistance regulating circuit according to claim 5, wherein the second switch tube driving circuit unit comprises a second NMOS tube and a second driving power supply input end; wherein:

7. The IGBT gate resistance regulating circuit according to any one of claims 4 to 6, wherein the third switch tube driving circuit unit comprises a third NMOS tube and a third driving power supply input end; wherein:

8. The IGBT gate resistance regulator circuit according to claim 4, wherein the first gate resistance has a value greater than the second gate resistance.

9. An air conditioner, characterized in that, the air conditioner includes the IGBT tube gate resistance adjusting circuit of any one of claims 1 to 8.