Negative voltage IGBT drive circuit with undervoltage protection function based on discrete devices

Abstract

The present invention discloses a negative voltage IGBT driving circuit with an undervoltage protection function constructed based on discrete devices, and the circuit includes an optocoupler input circuit, an undervoltage protection circuit, and a negative voltage shutdown circuit. The optocoupler input circuit isolates and outputs a driving pulse signal emitted by an MCU; the undervoltage protection circuit shuts off the driving pulse output by the optocoupler input circuit when the on-voltage is lower than a threshold; the negative voltage circuit forms a negative voltage as the shutdown voltage of the IGBT, thereby protecting the IGBT. On the basis of the IGBT driving circuit, the present invention adds an undervoltage protection circuit and a negative voltage shutdown circuit to realize the IGBT protection function, improve safety, and reduce the risk of damage to the IGBT device.

Description

Technical Field

[0001] The invention relates to the technical field of AC servo driver IGBT drive control, in particular to a negative voltage IGBT drive circuit with an undervoltage protection function constructed based on discrete devices. Background Art

[0002] IGBT (Insulated Gate Bipolar Transistor) is a composite device, a voltage-type power semiconductor device, with the advantages of high input impedance, high switching frequency, easy to drive, etc., so it is widely used in electric vehicles, servo drives and switching power supplies. Among them, servo drives are widely used in various fields, such as transmitters, follow-up devices, radar systems, etc.

[0003] At present, the IGBT drive circuits that are widely used in the market mostly use dedicated integrated drive circuits and thick film drive circuits. Although these drive circuits have advantages such as high degree of integration, perfect protection functions and strong anti-interference ability, they are expensive and most of them are produced by foreign manufacturers. In recent years, as the country advocates 100% localization of electronic components, some dedicated integrated drive circuits and thick film drive circuits can no longer meet the use requirements of servo drives in various fields. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a negative voltage IGBT drive circuit with undervoltage protection function based on discrete devices, integrating the negative voltage drive circuit and the undervoltage protection function, simplifying the peripheral circuit structure, improving the IGBT shutdown speed, and increasing the reliability of turning on and off, while achieving the 100% localization demand for components.

[0005] The purpose of the present invention is achieved in this way: a negative voltage IGBT drive circuit with an undervoltage protection function is constructed based on discrete devices, and its characteristics are: it includes an optocoupler input circuit, an undervoltage protection circuit and a negative voltage shutdown circuit that are interconnected; the optocoupler input circuit isolates and outputs the drive signal PWM_UH issued by the MCU; the undervoltage protection circuit shuts off the output pulse of the optocoupler input circuit when the on-voltage is lower than the threshold; the negative voltage shutdown circuit and the undervoltage protection circuit are integrated together, and the negative voltage shutdown circuit constitutes a negative voltage as the shutdown voltage of the IGBT.

[0006] Preferably, the optocoupler input circuit includes an optocoupler, a first resistor, a second resistor and a first capacitor, one end of the first resistor is connected to the drive signal PWM_UH issued by the MCU, the other end of the first resistor is connected to the Cath end of the optocoupler, one end of the second resistor connected in parallel with the first capacitor is connected to the Anode end of the optocoupler, and the other end is connected between the first resistor and the Cath end of the optocoupler.

[0007] Preferably, the undervoltage protection circuit includes a transistor, a first voltage regulator, a second voltage regulator, a third resistor, a fourth resistor, an eighth resistor, a second capacitor, and a third capacitor; the collector of the transistor is connected to the VCC port of the optocoupler, the emitter of the transistor is connected to the power supply, the base of the transistor, one end of the eighth resistor, and one end of the fourth resistor are connected, the other end of the eighth resistor is connected to the power supply, the other end of the fourth resistor is connected to the cathode of the second voltage regulator, the anode of the second voltage regulator is connected to the cathode of the first voltage regulator, and the anode of the first voltage regulator is connected to the power ground; one end of the second capacitor is connected to the collector of the transistor, and the other end of the second capacitor is connected to the power ground; one end of the third resistor and the third capacitor in parallel is connected to the VO end of the optocoupler, and the other end is connected to the power ground.

[0008] Preferably, the negative voltage shutdown circuit includes a third voltage regulator tube, a fourth voltage regulator tube, a gate resistor, a seventh resistor, a fifth capacitor, a seventh capacitor, an eighth capacitor and a ninth capacitor; the first end of the gate resistor is connected to the VO end of the optocoupler, and the second end of the gate resistor outputs a drive signal; the cathode of the fourth voltage regulator tube is connected to the second end of the gate resistor, the anode of the fourth voltage regulator tube is connected to the anode of the third voltage regulator tube, and the cathode of the third voltage regulator tube is connected to the ground; one end of the seventh resistor and the ninth capacitor connected in parallel is connected to the second end of the gate resistor, and the other end is connected to the ground; One end of the fifth capacitor, the seventh capacitor, and the eighth capacitor connected in parallel is connected to the ground, and the other end is connected to the power ground, and the cathode of the first voltage regulator is connected to the ground; one end of the second capacitor is also connected to the VCC port of the optocoupler, and the Vee port of the optocoupler is connected to the power ground; the negative voltage shutdown circuit uses the first voltage regulator tube, the third voltage regulator tube, the fourth voltage regulator tube, the power ground, the VCC, VO, Vee ports of the optocoupler, the third resistor, the gate resistor, the seventh resistor, the second capacitor, the third capacitor, the fifth capacitor, the seventh capacitor, the eighth capacitor, the ninth capacitor and the ground to form DC -5.1V as the shutdown voltage of the IGBT.

[0009] The beneficial effects of the present invention are: using discrete devices to integrate negative pressure shutdown and undervoltage protection functions, simplifying the peripheral circuit structure, reducing the system hardware design cost, improving the IGBT shutdown speed, increasing the reliability of opening and closing, realizing the localization needs of devices, and meeting the special needs of equipment for servo drives. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 The present invention is a schematic diagram of a negative voltage IGBT drive circuit with an undervoltage protection function constructed based on discrete devices.

[0011] Figure 2 1 is a schematic diagram of an optocoupler input circuit according to an embodiment of the present invention.

[0012] Figure 31 is a schematic diagram of an undervoltage protection circuit according to an embodiment of the present invention.

[0013] Figure 4 1 is a schematic diagram of a negative pressure shutdown circuit according to an embodiment of the present invention. DETAILED DESCRIPTION

[0014] like Figures 1 to 4 As shown, a negative voltage IGBT drive circuit with undervoltage protection function is constructed based on discrete devices, including an optocoupler input circuit 1, an undervoltage protection circuit 2 and a negative voltage shutdown circuit 3 connected to each other. The optocoupler input circuit 1 isolates and outputs the drive signal PWM_UH sent by the MCU; the undervoltage protection circuit 2 shuts off the output pulse of the optocoupler input circuit 1 when the on-voltage of the collector of the transistor V5 is lower than the threshold; the negative voltage shutdown circuit 3 and the undervoltage protection circuit 2 are integrated together, and the negative voltage shutdown circuit 3 forms a negative voltage as the shutdown voltage of the IGBT.

[0015] The optocoupler input circuit 1 includes an optocoupler N1, a first resistor R1, a second resistor R2 and a first capacitor C1, one end of the first resistor R1 is connected to the drive signal PWM_UH issued by the MCU, the other end of the first resistor R1 is connected to the Cath end of the optocoupler N1, one end of the second resistor R2 connected in parallel with the first capacitor C1 is connected to the Anode end of the optocoupler N1, and the other end is connected between the first resistor R1 and the Cath end of the optocoupler N1. The optocoupler input circuit 1 uses a resistor current limiting method to connect the drive signal PWM_UH issued by the MCU to one end of the first resistor R1.

[0016] The undervoltage protection circuit 2 turns off the output pulse when the on-voltage of the collector of the transistor V5 is lower than the threshold value. The undervoltage protection circuit 2 includes a transistor V5, a first voltage regulator V1, a second voltage regulator V2, a third resistor R3, a fourth resistor R4, an eighth resistor R8, a second capacitor C2, and a third capacitor C3. The collector of the transistor V5 is connected to the VCC port of the optical coupler N1, the emitter of the transistor V5 is connected to the power supply P15U, the base of the transistor V5, one end of the eighth resistor R8, and one end of the fourth resistor R4 are connected, the other end of the eighth resistor R8 is connected to the power supply P15U, the other end of the fourth resistor R4 is connected to the cathode of the second voltage regulator V2, the anode of the second voltage regulator V2 is connected to the cathode of the first voltage regulator V1, and the anode of the first voltage regulator V1 is connected to the power ground M15U. One end of the second capacitor C2 is connected to the collector of the transistor V5, and the other end of the second capacitor C2 is connected to the power ground M15U. One end of the third resistor R3 and the third capacitor C3 connected in parallel is connected to the VO terminal of the optical coupler N1, and the other end is connected to the power ground M15U.

[0017] Attach Figure 3Taking the transistor V5 as an example for analysis, the voltage at point A between the base of the transistor V5 and the first end of the eighth resistor R8 is represented by Ud.

[0018] The specific working process of the undervoltage protection function is: when the power supply P15U works normally, the voltage Ud at point A is within the threshold voltage range of the transistor V5, the collector of the transistor V5 is turned on, the optocoupler N1 works normally, and the VO terminal of the optocoupler N1 outputs a drive pulse; when the power supply P15U is undervoltage, in the undervoltage protection circuit, the voltage at point A is obtained by dividing the eighth resistor R8 and the fourth resistor R4, resulting in a decrease in the voltage at point A, and the voltage at point A is lower than the turn-on voltage threshold range of the transistor V5. The collector of the transistor V5 does not output voltage, and there is no voltage input to the VCC port of the optocoupler N1, resulting in no drive pulse output at the VO terminal of the optocoupler N1, and an undervoltage protection signal is issued.

[0019] The negative voltage shutdown circuit 3 includes a third voltage regulator tube V3, a fourth voltage regulator tube V4, a gate resistor R6, a seventh resistor R7, a fifth capacitor C5, a seventh capacitor C7, an eighth capacitor C8 and a ninth capacitor C9. The first end of the gate resistor R6 is connected to the VO end of the optical coupler N1, and the second end of the gate resistor R6 outputs a driving signal. The cathode of the fourth voltage regulator tube V4 is connected to the second end of the gate resistor R6, the anode of the fourth voltage regulator tube V4 is connected to the anode of the third voltage regulator tube V3, and the cathode of the third voltage regulator tube V3 is connected to the ground UG. One end of the seventh resistor R7 and the ninth capacitor C9 connected in parallel is connected to the second end of the gate resistor R6, and the other end is connected to the ground UG. One end of the fifth capacitor C5, the seventh capacitor C7, and the eighth capacitor C8 connected in parallel is connected to the ground UG, and the other end is connected to the power ground M15U, and the cathode of the first voltage regulator tube V1 is connected to the ground UG. One end of the fifth capacitor C5 is also connected to the sixth capacitor C6, the other end of the sixth capacitor C6 is connected to the power supply P15U, one end of the seventh capacitor C7 is also connected to the fifth resistor R5, the other end of the fifth resistor R5 is connected to the power supply P15U. One end of the second capacitor C2 is also connected to the VCC port of the optical coupler N1, and the Vee port of the optical coupler N1 is connected to the power ground M15U.

[0020] The negative voltage shutdown circuit uses the first voltage regulator tube V1, the third voltage regulator tube V3, the fourth voltage regulator tube V4, the power ground M15U, the VCC, VO, Vee ports of the optocoupler N1, the third resistor R3, the gate resistor R6, the seventh resistor R7, the second capacitor C2, the third capacitor C3, the fifth capacitor C5, the seventh capacitor C7, the eighth capacitor C8, the ninth capacitor C9 and the ground UG to form DC -5.1V as the shutdown voltage of the IGBT.

[0021] In summary, the present invention constructs a negative voltage IGBT drive circuit with an undervoltage protection function based on discrete devices, has a simple control circuit, reduces costs, and achieves 100% localization of components.

[0022] The above implementation cases are only used to illustrate the technical solution of the present invention rather than to limit it. Any technician familiar with the profession may use the technical content disclosed above to change or modify it into equivalent implementation cases with equivalent changes and apply them to other fields. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A negative voltage IGBT drive circuit with undervoltage protection function is constructed based on discrete devices, which is characterized by: It includes an optocoupler input circuit, an undervoltage protection circuit and a negative voltage shutdown circuit connected to each other; The optocoupler input circuit isolates and outputs the drive signal PWM_UH issued by the MCU; the undervoltage protection circuit shuts off the output pulse of the optocoupler input circuit when the on-voltage is lower than the threshold; the negative voltage shutdown circuit and the undervoltage protection circuit are integrated together, and the negative voltage shutdown circuit forms a negative voltage as the shutdown voltage of the IGBT; the optocoupler input circuit includes an optocoupler, a first resistor, a second resistor and a first capacitor, one end of the first resistor is connected to the drive signal PWM_UH issued by the MCU, the other end of the first resistor is connected to the Cath end of the optocoupler, one end of the second resistor connected in parallel with the first capacitor is connected to the Anode end of the optocoupler, and the other end is connected between the first resistor and the Cath end of the optocoupler; the undervoltage The protection circuit includes a transistor, a first voltage-stabilizing tube, a second voltage-stabilizing tube, a third resistor, a fourth resistor, an eighth resistor, a second capacitor, and a third capacitor; the collector of the transistor is connected to the VCC port of the optocoupler, the emitter of the transistor is connected to the power supply, the base of the transistor, one end of the eighth resistor, and one end of the fourth resistor are connected, the other end of the eighth resistor is connected to the power supply, the other end of the fourth resistor is connected to the cathode of the second voltage-stabilizing tube, the anode of the second voltage-stabilizing tube is connected to the cathode of the first voltage-stabilizing tube, and the anode of the first voltage-stabilizing tube is connected to the power supply ground; one end of the second capacitor is connected to the collector of the transistor, and the other end of the second capacitor is connected to the power supply ground; one end of the third resistor and the third capacitor connected in parallel is connected to the VO end of the optocoupler, and the other end is connected to the power supply ground.

2. The negative voltage IGBT driving circuit with undervoltage protection function constructed based on discrete devices according to claim 1 is characterized in that: The negative voltage shutdown circuit includes a third voltage regulator tube, a fourth voltage regulator tube, a gate resistor, a seventh resistor, a fifth capacitor, a seventh capacitor, an eighth capacitor and a ninth capacitor; the first end of the gate resistor is connected to the VO end of the optocoupler, and the second end of the gate resistor outputs a driving signal; the cathode of the fourth voltage regulator tube is connected to the second end of the gate resistor, the anode of the fourth voltage regulator tube is connected to the anode of the third voltage regulator tube, and the cathode of the third voltage regulator tube is connected to the ground; one end of the seventh resistor and the ninth capacitor connected in parallel is connected to the second end of the gate resistor, and the other end is connected to the ground; one end of the fifth capacitor, the seventh capacitor and the eighth capacitor connected in parallel is connected to the ground, and the other end is connected to the power supply ground, and the cathode of the first voltage regulator tube is connected to the ground; one end of the second capacitor is also connected to the VCC port of the optocoupler, and the Vee port of the optocoupler is connected to the power supply ground; The negative voltage shutdown circuit uses a first voltage regulator tube, a third voltage regulator tube, a fourth voltage regulator tube, a power ground, VCC, VO, Vee ports of an optocoupler, a third resistor, a gate resistor, a seventh resistor, a second capacitor, a third capacitor, a fifth capacitor, a seventh capacitor, an eighth capacitor, a ninth capacitor and ground to form a DC -5.1V as a shutdown voltage of the IGBT.

Images