IGBT (Insulated Gate Bipolar Translator) driving circuit

Abstract

The utility model discloses an IGBT drive circuit comprising a power supply VCC, a signal drive circuit, a follow current protection circuit, a selection control circuit and a drive control circuit, the power supply VCC is electrically connected with the signal drive circuit and the selection control circuit respectively, the signal drive circuit is electrically connected with the follow current protection circuit and the drive control circuit respectively, and the drive control circuit is electrically connected with the follow current protection circuit. The follow current protection circuit is electrically connected with the selection control circuit and the driving control circuit respectively, the selection control circuit is electrically connected with the driving control circuit, and the selection control circuit comprises a first comparison circuit, a second comparison circuit and a switching circuit, the first comparison circuit is electrically connected with a power supply VCC, the follow current protection circuit and the second comparison circuit respectively; the second comparison circuit is electrically connected with the power supply VCC and the switching circuit. The switching circuit is electrically connected with the power supply VCC and the drive control circuit. The first comparison circuit and the second comparison circuit carry out voltage comparison, output different level signals, carry out on-off control on the drive control circuit, and further control on-off of the IGBT.

Description

Technical Field

[0001] The utility model relates to the field of circuits, and specifically, to an IGBT drive circuit. Background Art

[0002] In the field of switching power supplies, most switching power supplies are internally designed with a rectifier circuit and an inverter circuit. The rectifier circuit and the inverter circuit can be used to turn on and off the switching power supply, adjust the voltage of the switching power supply, etc. The current and voltage in these rectifier circuits and inverter circuits are relatively large, and ordinary electrical components cannot withstand large voltages and currents. Therefore, IGBTs are usually used to implement the on-off and voltage adjustment of the rectifier circuit and the inverter circuit, so as to control the on-off of the switching power supply and the adjustment of the switching power supply voltage.

[0003] However, switching losses will occur during the operation of IGBTs. Switching losses include turn-on losses and turn-off losses. If the losses are too large, not only will the temperature of the IGBT increase, resulting in damage to the IGBT, but also the power output efficiency of the switching power supply will be affected. In the drive circuit of the IGBT, the magnitude of the switching loss is related to the magnitude of the drive resistance Rs. The magnitude of the drive resistance Rs is one of the factors affecting its switching speed.

[0004] When Rs decreases, the switching speed can be increased and the losses can be reduced. On the contrary, the larger the drive resistance Rs, the slower the switching speed and the greater the losses. However, when the drive resistance Rs is too small, the du / dt (voltage change) and di / dt (current change) during the turn-on and turn-off of the IGBT will become larger, generating a large amount of EMI interference (electromagnetic interference), which will affect the normal operation of the IGBT.

[0005] As Figure 1 shown, in the prior art, different drive resistances R S1 and drive resistance R S2 are used as the turn-on resistance and the turn-off resistance to adjust the switching time of the IGBT. And the inherent characteristic of the IGBT is that the turn-off time is greater than the turn-on time. Therefore, the drive resistance R S1 is set to be smaller than the drive resistance R S2 , so as to increase the turn-on time of the IGBT and reduce the turn-off time. Therefore, the turn-off losses will be correspondingly reduced. However, in circuit design, the resistance R S2 cannot be set too small, otherwise the du / dt during the turn-off of the IGBT will become larger, and correspondingly, a large amount of EMI interference (electromagnetic interference) will be generated. Summary of the Utility Model

[0006] Aiming at the deficiencies of the prior art, the utility model provides an IGBT drive circuit,

[0007] The object of the present utility model is achieved through the following solutions:

[0008] An IGBT drive circuit includes: a power supply VCC, a signal drive circuit, a freewheeling protection circuit, a selection control circuit, and a drive control circuit. The power supply VCC is electrically connected to the signal drive circuit and the selection control circuit respectively. The signal drive circuit is electrically connected to the freewheeling protection circuit and the drive control circuit respectively. The freewheeling protection circuit is electrically connected to the selection control circuit and the drive control circuit respectively. The selection control circuit is electrically connected to the drive control circuit. The selection control circuit includes a first comparison circuit, a second comparison circuit, and a switch circuit. The first comparison circuit is electrically connected to the power supply VCC, the freewheeling protection circuit, and the second comparison circuit respectively. The second comparison circuit is electrically connected to the power supply VCC and the switch circuit respectively. The switch circuit is electrically connected to the power supply VCC and the drive control circuit respectively.

[0009] In one embodiment, the first comparison circuit includes a voltage stabilizing module, a first comparison module, and a voltage dividing module. The voltage stabilizing module is electrically connected to the power supply VCC, the first comparison module, and the voltage dividing module respectively, and is also grounded to GND. The first comparison module is electrically connected to the power supply VCC, the voltage dividing module, the freewheeling protection circuit, and the second comparison circuit respectively, and is also grounded to GND. The voltage dividing module is electrically connected to the freewheeling protection circuit and is also grounded.

[0010] In one embodiment, the second comparison circuit includes a reference power supply Vref, a first protection module, and a second comparison module. The first protection module is electrically connected to the first comparison circuit and the second comparison module respectively. The second comparison module is electrically connected to the reference power supply Vref and the switch circuit respectively.

[0011] In one embodiment, the switch circuit includes a second protection module, a first tuning module, and a switch module. The second protection module is electrically connected to the second comparison circuit and the first tuning module respectively. The first tuning module is electrically connected to the switch module. The switch module is electrically connected to the drive control circuit.

[0012] In one embodiment, the signal drive circuit includes a negative voltage power supply VEE and a push-pull module. The power supply VCC is electrically connected to the push-pull module. The negative voltage power supply VEE is electrically connected to the push-pull module. The push-pull module is electrically connected to the drive control circuit, and a signal input is externally connected to the push-pull module.

[0013] In one embodiment, the freewheeling protection circuit includes a first freewheeling module and a second freewheeling module. The first freewheeling module is electrically connected to the second freewheeling module, the selection control circuit, and the drive control circuit respectively. The second freewheeling module is electrically connected to the selection control circuit and the drive control circuit respectively.

[0014] In one embodiment, the drive control circuit includes a second voltage dividing module, a third voltage dividing module, a conduction module, a breaking module, a third tuning module, and an IGBT module. The second voltage dividing module is electrically connected to the freewheeling protection circuit, the conduction module, and the signal drive circuit respectively; the third voltage dividing module is electrically connected to the freewheeling protection circuit and the IGBT module respectively; the conduction module is electrically connected to the signal drive circuit, the second voltage dividing module, the breaking module, and the third tuning module respectively; the breaking module is electrically connected to the third tuning module; the third tuning module is electrically connected to the IGBT module; the IGBT module is also grounded to GND.

[0015] In one embodiment, the output voltage of the power supply VCC is a positive voltage, and the output voltage of the negative voltage power supply VEE is a negative voltage.

[0016] Compared with the prior art, the present utility model has at least the following advantages:

[0017] An IGBT drive circuit of the present utility model controls the turn-on and turn-off of the IGBT effectively by setting the first comparison circuit, the second comparison circuit, and the switch circuit in the selection control circuit, comparing voltages through the first comparison circuit and the second comparison circuit, and then outputting different level signals to control the turn-on and turn-off of the drive control circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings described herein are used to provide a further understanding of the present application, and constitute a part of the present application. The schematic embodiments of the present application and their descriptions are used to explain the present application, and do not constitute an improper limitation of the present application. In the drawings:

[0019] Figure 1 is the IBGT drive circuit diagram in the prior art;

[0020] Figure 2 is the circuit diagram of an IGBT drive circuit of the present utility model;

[0021] Among them, the reference numerals are: 1 power supply VCC; 2 signal drive circuit; 21 negative voltage power supply VEE; 22 push-pull module; 3 freewheeling protection circuit; 31 first freewheeling module; 32 second freewheeling module; 4 selection control circuit; 41 first comparison circuit; 411 voltage stabilization module; 412 first comparison module; 413 first voltage dividing module;

[0022] 42 second comparison circuit; 421 first protection module; 422 second comparison module; 43 switch circuit; 431 second protection module; 432 first tuning module; 433 switch module; 5 drive control circuit; 51 second voltage dividing module; 52 third voltage dividing module; 53 conduction module; 54 breaking module; 55 third tuning module; 56 IGBT module. Detailed implementation manners

[0023] The following will disclose multiple implementation manners of the present utility model with the aid of drawings. For the sake of clear description, many practical details will be described together in the following narrative. However, it should be understood that these practical details are not used to limit the present utility model. That is to say, in some implementation manners of the present utility model, these practical details are not necessary. In addition, for the purpose of simplifying the drawings, some conventional structures and components will be illustrated in a simple schematic manner in the drawings.

[0024] It should be noted that all directional indications such as up, down, left, right, front, back... in the embodiments of the present utility model are only used to explain the relative positional relationship and movement conditions between components in a specific posture as shown in the drawings. If this specific posture changes, then the directional indication will also change accordingly.

[0025] In addition, in the present utility model, descriptions such as "first", "second", etc. are only for descriptive purposes, and do not particularly refer to the order or sequence, nor are they used to limit the present utility model. It is only used to distinguish components or operations described with the same technical terms, and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement them. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present utility model.

[0026] In order to further understand the content, features and effects of the present utility model, the following embodiments are exemplified and described in detail with reference to the drawings as follows:

[0027] As Figure 2 shown, the present utility model provides an IGBT drive circuit, including: a power supply VCC1, a signal drive circuit 2, a freewheeling protection circuit 3, a selection control circuit 4 and a drive control circuit 5. The power supply VCC1 is electrically connected to the signal drive circuit 2 and the selection control circuit 4 respectively. The signal drive circuit 2 is electrically connected to the freewheeling protection circuit 3 and the drive control circuit 5 respectively. The freewheeling protection circuit 3 is electrically connected to the selection control circuit 4 and the drive control circuit 5 respectively. The selection control circuit 4 is electrically connected to the drive control circuit 5.

[0028] It should be noted that the power supply VCC1 inputs electrical energy to the circuit components of the IGBT drive circuit; the signal drive circuit 2 can be used to improve the load capacity of the IGBT drive circuit and increase the speed of the on and off circuits; the freewheeling protection circuit can limit the current of the IGBT drive circuit and ensure that the current continues to flow when the circuit components are turned off, which helps to reduce the sharp change of current and noise interference and maintain the continuity in the circuit; when the IGBT drive circuit is working specifically, the selection control circuit 4 can perform on and off control operations on the drive control circuit 5, and the drive control circuit 5 can be connected to electrical equipment with large voltage and large current, so that the entire IGBT drive circuit can accurately control the electrical equipment with large voltage and large current.

[0029] Specifically, as Figure 2 shown, the selection control circuit 4 includes a first comparison circuit 41, a second comparison circuit 42 and a switch circuit 43. The first comparison circuit 42 is electrically connected to the power supply VCC1, the freewheeling protection circuit 3 and the second comparison circuit 43 respectively. The second comparison circuit 43 is electrically connected to the power supply VCC1 and the switch circuit 43 respectively. The switch circuit 43 is electrically connected to the power supply VCC1 and the drive control circuit 5 respectively. Among them, the power supply VCC1 provides electrical energy input to the first comparison circuit 41 and the second comparison circuit 42. The voltage values are compared inside the first comparison circuit 41 and the second comparison circuit 42. Finally, the first comparison circuit 42 and the second comparison circuit 43 will output the one with the larger voltage value as a digital signal.

[0030] Specifically, as Figure 2 shown, the first comparison circuit 41 includes a voltage stabilization module 411, a first comparison module 412 and a first voltage division module 413. The voltage stabilization module 411 is electrically connected to the power supply VCC1, the first comparison module 412 and the first voltage division module 413 respectively, and is also grounded to GND; the first comparison module 412 is electrically connected to the power supply VCC1, the first voltage division module 413, the freewheeling protection circuit 3 and the second comparison circuit 42 respectively, and is also grounded to GND; the first voltage division module 413 is electrically connected to the freewheeling protection circuit 3 and is also grounded.

[0031] Among them, the voltage stabilization module 411 includes a resistor R1, a voltage stabilizing diode U2 and a capacitor C1. The resistor R1 and the capacitor C1 each have a terminal 1 and a terminal 2, and the voltage stabilizing diode U2 has terminals 1 - 3; the first comparison module 412 includes an operational amplifier U1A, and the operational amplifier U1A has terminals 1 - 5; the first voltage division module 413 includes a resistor R2 and a capacitor C2. The resistor R2 and the capacitor C2 each have a terminal 1 and a terminal 2.

[0032] It should be noted that the No. 1 terminal of the resistor R1 is electrically connected to the power supply VCC1, and the No. 2 terminal of the resistor R1 is electrically connected to the No. 1 terminal of the voltage stabilizing diode U2 and the No. 2 terminal of the operational amplifier U1A respectively; the No. 1 terminal of the voltage stabilizing diode U2 is electrically connected to the No. 2 terminal of the operational amplifier U1A, the No. 2 terminal of the voltage stabilizing diode U2 is grounded, and is electrically connected to the No. 2 terminals of the capacitor C1, the resistor R2, the capacitor C2 and the No. 4 terminal of the operational amplifier respectively, and the No. 3 terminal of the voltage stabilizing diode U2 is electrically connected to the No. 2 terminal of the operational amplifier U1A and the No. 1 terminal of the capacitor C1 respectively; the No. 1 terminal of the capacitor C1 is electrically connected to the No. 2 terminal of the operational amplifier; the No. 1 terminal of the operational amplifier U1A is electrically connected to the second comparison circuit 42, the No. 3 terminal of the operational amplifier U1A is electrically connected to the No. 1 terminal of the resistor R2, the No. 1 terminal of the capacitor C2 and the freewheeling protection circuit 3 respectively, the No. 4 terminal of the operational amplifier U1A is grounded, and the No. 5 terminal of the operational amplifier U1A is electrically connected to the power supply VCC1; the No. 1 terminal and the No. 2 terminal of the resistor R2 are connected in parallel with the No. 1 terminal and the No. 2 terminal of the capacitor C2, the No. 1 terminal of the resistor R2 and the No. 1 terminal of the capacitor C2 are electrically connected to the freewheeling protection circuit 3, and the No. 2 terminal of the resistor R2 and the No. 2 terminal of the capacitor C2 are grounded.

[0033] During specific operation, the voltage of the power supply VCC1 is input to the voltage stabilizing diode U2 after passing through R1, and is also input to the operational amplifier U1A, enabling both to operate normally. The voltage stabilizing diode U2 generates a voltage value and inputs it to the operational amplifier U1A as a comparison voltage, and the comparison voltage does not have voltage fluctuations, making the first comparison circuit 41 operate more stably; the capacitor C1 filters the comparison voltage to reduce voltage ripple; the capacitor C2 filters the voltage on R2 to reduce voltage ripple. R2 serves as a voltage dividing resistor to divide the voltage on the branch connected to the freewheeling protection circuit. Depending on the specific situation, the voltage at the No. 3 terminal of the operational amplifier U1A is greater than or less than the above-mentioned comparison voltage, and then a high-level or low-level signal is output.

[0034] Specifically, such as Figure 2As shown in the figure, the second comparison circuit 42 includes a reference power supply Vref, a first protection module 421, and a second comparison module 422. The first protection module 421 is electrically connected to the first comparison circuit 41 and the second comparison module 422 respectively, and the second comparison module 422 is electrically connected to the reference power supply Vref and the switch circuit 43 respectively. Among them, the first protection module 421 includes a resistor R3 and a diode D2. The resistor R3 and the diode D2 each have a terminal 1 and a terminal 2. The second comparison module 422 includes an operational amplifier U1B, and the operational amplifier U1B has terminals 1-3. It should be noted that the terminal 1 of the resistor R3 is electrically connected to the power supply VCC1, the terminal 2 of the resistor R3 is electrically connected to the first comparison circuit 41 and the diode D2 respectively; the terminal 1 of the diode D2 is electrically connected to the first comparison circuit 41, and the terminal 2 of the diode D2 is electrically connected to the terminal 2 of the operational amplifier U1B; the terminal 1 of the operational amplifier U1B is electrically connected to the switch circuit 43, and the terminal 2 of the operational amplifier U1B is electrically connected to the reference power supply Vref. During specific operation, the voltage of the power supply VCC1 is input to the terminal 2 of the operational amplifier U1B, the reference power supply Vref is input to the terminal 3 of the operational amplifier U1B. At this time, the level signal output by the first comparison circuit 41 is input to the terminal 2 of the operational amplifier U1B, determining the positive and negative of the voltage of the power supply VCC1. Finally, the reference power supply Vref is compared with the power supply VCC1, and the operational amplifier U1B thus outputs a high-level or low-level signal. R3 functions as current-limiting protection to prevent damage to the operational amplifier, and the diode D2 functions as a freewheeling diode to ensure the stability of the circuit.

[0035] Specifically, as Figure 2 shown in the figure, the switch circuit 43 includes a second protection module 431, a first tuning module 432, and a switch module 433. The second protection module 431 is electrically connected to the second comparison circuit and the first tuning module 432 respectively, the first tuning module 432 is electrically connected to the switch module 433, and the switch module 433 is electrically connected to the drive control circuit 5. Among them, the second protection module 431 includes a resistor R4 and a diode D3. The resistor R4 and the diode D3 each have a terminal 1 and a terminal 2. The first tuning module 432 includes a resistor R5 and a capacitor C3. The resistor R5 and the capacitor C3 each have a terminal 1 and a terminal 2. The switch module 433 includes a triode Q1, and the triode Q1 has a collector C, a base B, and an emitter E.

[0036] It should be noted that the 1st terminal of resistor R4 is electrically connected to the power supply VCC1, and the 2nd terminal of resistor R4 is electrically connected to the second comparison circuit 42 and diode D3 respectively; the 1st terminal of diode D3 is electrically connected to the second comparison circuit 42, and the 2nd terminal of diode D2 is electrically connected to the 1st terminal of resistor R5, capacitor C3 and the base B of triode Q1 respectively; the 1st terminal and the 2nd terminal of resistor R5 are connected in parallel with the 1st terminal and the 2nd terminal of capacitor C3, the 1st terminal of resistor R5 and the 1st terminal of capacitor C3 are electrically connected to the base B of triode Q1, and the 2nd terminal of resistor R5 and the 2nd terminal of capacitor C3 are grounded; the emitter E of triode Q1 is grounded, and the collector of triode Q1 is electrically connected to the drive control circuit 5. During specific operation, the power supply VCC1 inputs voltage, the base B of triode Q1 is the control terminal, and through the high level or low level output by the second comparison circuit, it controls the input voltage of the power supply VCC1 to be a positive voltage or a negative voltage, thereby controlling the on-off of triode Q1. The functions of resistor R4 and triode D3 are the same as those of resistor R3 and triode D2. Resistor R5 and capacitor C3 are connected in parallel as a filter, which can effectively suppress the interference received by the circuit. The on-off of triode Q1 controls the switch of the drive control circuit 5.

[0037] As Figure 2 shown, the signal drive circuit 2 includes a negative voltage power supply VEE 21 and a push-pull module 22. The power supply VCC1 is electrically connected to the push-pull module 22, the emitter power supply VEE 21 is electrically connected to the push-pull module 22, the push-pull module 22 is electrically connected to the drive control circuit, and a signal input is externally connected to the push-pull module 22. Among them, the push-pull module 22 includes triode Q2 and triode Q3, and triode Q2 and triode Q3 respectively have a collector C, a base B and an emitter E.

[0038] It should be noted that the bases B of triode Q2 and triode Q3 are electrically connected to the externally input signal, the collector C of triode Q2 is electrically connected to the power supply VCC1, and the emitter E of triode Q2 is electrically connected to the emitter E of triode Q3 and the drive control circuit 5 respectively; the emitter E of triode Q3 is electrically connected to the drive control circuit 5, and the collector C of triode Q3 is electrically connected to the negative voltage power supply VEE 21. During specific operation, the externally input signal is PWM, and the PWM signal is provided by the MCU. According to the high level or low level of the input PWM signal to the bases B of triode Q2 and triode Q3, it controls the conduction and cut-off of triode Q2 and triode Q3, and further controls the on-off of the drive control circuit 5.

[0039] Specifically, as Figure 2As shown, the freewheeling protection circuit 3 includes a first freewheeling module 31 and a second freewheeling module 32. The first freewheeling module 31 is electrically connected to the second freewheeling module 32, the selection control circuit 4, and the drive control circuit 5 respectively; the second freewheeling module 32 is electrically connected to the selection control circuit 4 and the drive control circuit 5 respectively. Among them, the first freewheeling module includes a diode D4, the second freewheeling module includes a diode D5, and the diode D4 and the diode D5 each have a terminal 1 and a terminal 2.

[0040] It should be noted that the terminal 1 of the diode D4 is electrically connected to the drive control circuit 5, the terminal 2 of the diode D4 is electrically connected to the terminal 2 of the diode D5 and the selection control circuit 4 respectively, the terminal 1 of the diode D5 is electrically connected to the drive control circuit 5, and the terminal 2 of the diode D5 is electrically connected to the selection control circuit 4. During specific operation, the diode D4 and the diode D5 can form a loop with other components to play a freewheeling role and maintain the stable operation of the circuit.

[0041] Specifically, as Figure 2 shown, the drive control circuit 5 includes a second voltage dividing module 51, a third voltage dividing module 52, a conduction module 53, a breaking module 54, a third tuning module 55, and an IGBT module 55. The second voltage dividing module 51 is electrically connected to the freewheeling protection circuit 3, the conduction module 53, and the signal drive circuit 2 respectively; the third voltage dividing module 52 is electrically connected to the freewheeling protection circuit 3 and the IGBT module 55 respectively; the conduction module 53 is electrically connected to the signal drive circuit 2, the second voltage dividing module 51, the breaking module 54, and the third tuning module 55 respectively; the breaking module 54 is electrically connected to the third tuning module 55; the third tuning module 55 is electrically connected to the IGBT module 55; the IGBT module is also grounded to GND. Among them, the second voltage dividing module 51 includes a resistor R7, and the resistor R7 has a terminal 1 and a terminal 2; the third voltage dividing module 52 includes a resistor Rre, and the resistor Rre has a terminal 1 and a terminal 2; the conduction module 53 includes a resistor Ron, and the resistor Ron has a terminal 1 and a terminal 2; the breaking module 54 includes a resistor Roff, and the resistor Roff has a terminal 1 and a terminal 2; the third tuning module 55 includes a resistor R6 and a capacitor C4, and the resistor R6 and the capacitor C4 have a terminal 1 and a terminal 2; the IGBT module 55 is an IGBT, and the IGBT has a gate G, a collector C, and an emitter E.

[0042] It should be noted that the No. 1 terminal of resistor R7 is electrically connected to the No. 1 terminal of resistor Ron and the signal driving circuit 2 respectively, and the No. 2 terminal of resistor R7 is electrically connected to the freewheeling protection circuit 3; the No. 1 terminal of resistor Rre is electrically connected to the freewheeling protection circuit 3, and the No. 2 terminal of resistor Rre is electrically connected to the collector C of the IGBT; the No. 1 terminal of resistor Ron is electrically connected to the signal driving circuit 2, and the No. 2 terminal of resistor Ron is electrically connected to the Roff terminal, the No. 1 terminals of resistor R6 and capacitor C4 respectively; the No. 1 terminal of resistor Roff is electrically connected to the No. 1 terminals of resistor R6 and capacitor C4 respectively, and the No. 2 terminal of resistor Roff is electrically connected to the selection control circuit 4; resistor R6 is connected in parallel with the No. 1 and No. 2 terminals of capacitor C4 respectively, the No. 1 terminal is electrically connected to the gate G of the IGBT, and the No. 2 terminal is grounded to GND; the emitter E of the IGBT is grounded to GND. During specific operation, resistors R7 and Rre serve as voltage dividing resistors. According to the resistance values of resistors R7 and Rre, the voltage input to the branch where resistors R7 and Rre are located from the power supply VCC1 is divided. Resistors Ron and Roff serve as on-resistance and off-resistance to control the on and off of the switching circuit. Resistors R6 and capacitor C4 are connected in parallel as a filter, which has the same function as the parallel connection of resistor R5 and capacitor C3. The IGBT can be connected to electrical equipment with high voltage and large current, thereby precisely controlling the electrical equipment with high voltage and large current.

[0043] Preferably, as Figure 2 shown, the power supply VCC1 outputs a positive voltage, and the negative voltage power supply VEE 21 outputs a negative voltage as a negative voltage. It should be noted that since transistor Q2 is an NPN-type transistor and transistor Q3 is a PNP-type transistor, according to the high and low levels of the input PWM signal and the input positive voltage and negative voltage, bidirectional conduction of transistor Q2 and transistor Q3 can be achieved, thereby processing positive and negative half-cycle signals.

[0044] In summary, during specific implementation, when the PWM signal is at a high level, it is output by transistor Q2, and the current flowing through the collector C and emitter E of the IGBT forms a loop through resistor R7, diode D4, and resistor R2. At this time, a voltage V R2 is obtained across resistor R2 and input to the non-inverting input terminal No. 3 of operational amplifier U1A. The power supply VCC1 is input to voltage regulator U2, causing voltage regulator U2 to output a voltage. In this example, the output voltage of voltage regulator U2 is 2.5V. The output voltage of voltage regulator U2 enters the No. 2 terminal of operational amplifier U1A. Operational amplifier U1A compares the two voltages. In this example, the resistance value of resistor R2 is set to be greater than that of resistor R7, so that the voltage obtained across resistor R2 is greater than 2.5V, ensuring that U1A outputs a high level.

[0045] The high-level signal is input to the 2nd terminal of operational amplifier U1B together with the voltage of power supply VCC1, and the reference power supply Vref is also input to the 3rd terminal of operational amplifier U1B. In this way, operational amplifier U1B compares the two voltages and finally outputs a low level to the base of triode Q3. Triode Q1 is cut off, resistor Roff is disconnected, and the normal conduction of the IGBT is not affected.

[0046] When a low-level PWM signal is input, at this time, the output is performed by triode Q3, and the IGBT starts to turn off. As a result, the loop of diode D4 and resistor R7 is disconnected. Since the 3rd terminal of operational amplifier U1A is grounded and the input voltage of the 2nd terminal provides a voltage of 2.5V for voltage regulator U2, the output level of operational amplifier U1A should be output from the 2nd terminal, and the 2nd terminal outputs a low level at this time. When the low level enters operational amplifier U1B and is compared with the reference power supply Vref, at this time, the reference power supply Vref is greater than the low level, and operational amplifier U1B outputs a high level, causing triode Q1 to conduct. A loop is formed between Roff and the gate G of the IGBT. In this example, the resistance of Roff can be set very small, and the charge of the gate G of the IGBT will quickly discharge along the loop with a small resistance value of resistor Roff, so that the IGBT can be quickly turned off.

[0047] As can be seen from the above, when the discharge speed of the IGBT is too fast, it will cause the voltage of the collector C of the IGBT to be too high. In this example, the resistance value of resistor R2 is set so that the voltage value on resistor R2 is equal to 2.5V. When the IGBT is quickly turned off through resistor Roff, the dv / dt change of the IGBT accelerates. When the voltage on resistor R2 exceeds 2.5V, operational amplifier U1A outputs a high level, operational amplifier U1B outputs a low level, triode Q1 is turned off, resistor Roff disconnects the loop, and finally the IGBT turn-off loop is changed from resistor Roff to resistor Ron for discharging. In this example, the set resistor Ron is greater than resistor Roff, so the turn-off speed slows down and the dv / dt change becomes slower, thereby suppressing the generation of overvoltage of the IGBT.

[0048] The above is only the implementation mode of the present invention and is not used to limit the present invention. For those skilled in the art, various changes and modifications can be made to the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the scope of the claims of the present invention.

Claims

1. An IGBT driving circuit, characterized in that: include: A power supply VCC (1), a signal drive circuit (2), a freewheeling protection circuit (3), a selection control circuit (4) and a drive control circuit (5); the power supply VCC (1) is electrically connected to the signal drive circuit (2) and the selection control circuit (4), respectively; the signal drive circuit (2) is electrically connected to the freewheeling protection circuit (3) and the drive control circuit (5), respectively; the freewheeling protection circuit (3) is electrically connected to the selection control circuit (4) and the drive control circuit (5), respectively; the selection control circuit (4) is electrically connected to the drive control circuit (5); the selection control circuit (4) comprises a first comparison circuit (41), a second comparison circuit (42) and a switch circuit (43); the first comparison circuit (41) is electrically connected to the power supply VCC (1), the freewheeling protection circuit (3) and the second comparison circuit (42), respectively; the second comparison circuit (42) is electrically connected to the power supply VCC (1) and the switch circuit (43), respectively; the switch circuit (43) is electrically connected to the power supply VCC (1) and the drive control circuit (5), respectively.

2. An IGBT driving circuit according to claim 1, characterized in that: The first comparison circuit (41) comprises a voltage stabilizing module (411), a first comparison module (412) and a first voltage dividing module (413); the voltage stabilizing module (411) is electrically connected to a power supply VCC (1), the first comparison module (412) and the voltage dividing module (423) respectively, and is also connected to a ground GND; the first comparison module (412) is electrically connected to a power supply VCC (1), the first voltage dividing module (413), a freewheeling protection circuit (3) and a second comparison circuit (42) respectively, and is also connected to a ground GND; the first voltage dividing module (413) is electrically connected to the freewheeling protection circuit (3) and is also connected to a ground.

3. An IGBT driving circuit according to claim 1, characterized in that: The second comparison circuit (42) comprises a reference power supply Vref, a first protection module (421) and a second comparison module (422). The first protection module (421) is electrically connected to the first comparison circuit (41) and the second comparison module (422) respectively, and the second comparison module (422) is electrically connected to the reference power supply Vref and the switch circuit (43) respectively.

4. The IGBT driving circuit according to claim 1, characterized in that: The switch circuit (43) comprises a second protection module (431), a first tuning module (432) and a switch module (433); the second protection module (431) is electrically connected to the second comparison circuit and the first tuning module (432), respectively; the first tuning module (432) is electrically connected to the switch module (433); and the switch module (433) is electrically connected to the drive control circuit (5).

5. The IGBT driving circuit according to claim 1, characterized in that: The signal driving circuit (2) comprises a negative voltage power supply VEE (21) and a push-pull module (22); the power supply VCC (1) is electrically connected to the push-pull module (22); the negative voltage power supply VEE (21) is electrically connected to the push-pull module (22); the push-pull module (22) is electrically connected to the driving control circuit (5); and the push-pull module (22) is externally connected to a signal input.

6. The IGBT driving circuit according to claim 1, characterized in that: The freewheeling protection circuit (3) comprises a first freewheeling module (31) and a second freewheeling module (32); the first freewheeling module (31) is electrically connected to the second freewheeling module (32), the selection control circuit (4) and the drive control circuit (5) respectively; and the second freewheeling module (32) is electrically connected to the selection control circuit (4) and the drive control circuit (5) respectively.

7. The IGBT driving circuit according to claim 1, characterized in that: The drive control circuit (5) comprises a second voltage dividing module (51), a third voltage dividing module (52), a conduction module (53), a disconnection module (54), a third tuning module (55) and an IGBT module (56); the second voltage dividing module (51) is electrically connected to the freewheeling protection circuit (3), the conduction module (53) and the signal driving circuit (2) respectively; the third voltage dividing module (52) is electrically connected to the freewheeling protection circuit (3) and the IGBT module (56) respectively; the conduction module (53) is electrically connected to the signal driving circuit (2), the second voltage dividing module (51), the disconnection module (54) and the third tuning module (55) respectively; the disconnection module (54) is electrically connected to the third tuning module (55); the third tuning module (55) is electrically connected to the IGBT module (56); and the IGBT module (56) is also grounded GND.

8. The IGBT driving circuit according to claim 1, characterized in that: The power supply VCC (1) outputs a positive voltage, and the negative voltage power supply VEE (21) outputs a negative voltage.

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