High-voltage isolation driving circuit

Abstract

The invention relates to the field of high-voltage isolation driving circuits, in particular to a high-voltage isolation driving circuit. Comprising an isolation device 1, a discrete device driving circuit 2 and a driven device 3, an input port of the isolation device receives externally input PWM driving signals, after the signals are isolated, the isolation device outputs the PWM signals to the discrete device driving circuit, and the discrete device driving circuit comprises a triode Q1, a triode Q2, a triode Q3, a resistor R1, a resistor R2, a resistor R4, a resistor R5, a capacitor C1 and a diode V1. A driven MOS tube is driven through a triode Q1, a triode Q2 and a triode Q3, and a bootstrap circuit is formed by a diode V1, a capacitor C1 and a resistor R2 and can provide driving current when the triode Q1 is conducted, so that the triode Q1 can be started more quickly. The invention is suitable for the low-cost high-voltage isolation driving circuit.

Description

Technical Field

[0001] This invention relates to the field of high-voltage isolation drive circuits, and more specifically to a high-voltage isolation drive circuit. Background Technology

[0002] In fields such as power electronics, industrial automation, new energy, and medical equipment, high-voltage isolation drive circuits are a key technology for achieving safe and reliable signal transmission and power control. Because a kilovolt-level voltage difference exists between high-voltage systems (such as IGBTs, SiC / GaN devices, motor drives, inverters, etc.) and low-voltage control circuits (such as MCUs, DSPs), direct electrical connection would lead to serious safety hazards and signal interference. Therefore, electrical isolation technology must be employed to ensure that there is no direct current path between the high-voltage and low-voltage sides, while simultaneously achieving efficient and accurate signal transmission.

[0003] Existing technologies typically employ digital isolators with integrated isolation driver chips to improve system performance and stability, but these technologies are complex and costly. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a high-voltage isolation drive circuit that simplifies the circuit structure, ensures reliability, and greatly reduces costs.

[0005] The present invention achieves the above objectives by adopting the following technical solution: the present invention provides a high-voltage isolation drive circuit, comprising: The system includes an isolation device 1, a discrete device driving circuit 2, and a driven device 3. The isolation device 1 comprises an input section and an output section. The discrete device driving circuit 2 includes a first transistor Q1, a second transistor Q2, a third transistor Q3, a first resistor R1, a second resistor R2, a fourth resistor R4, a fifth resistor R5, a first capacitor C1, and a first diode V1. The driven device 3 includes a MOSFET Q4. The isolation device receives an externally input PWM drive signal. The positive terminal of the input section of the isolation device is connected to the signal input, and the negative terminal is grounded. The output port of the isolation device is connected to the base of the second transistor Q2. The base of the transistor is connected to the 12V voltage terminal through the first resistor R1 and to the anode of the first diode V1. The cathode of the first diode V1 is connected to the emitter of the first transistor Q1 through the first capacitor C1. The cathode of the first diode V1 is also connected to the collector of the second transistor Q2 through the second resistor R2. The collector of the second transistor Q2 is also connected to the base of the first transistor Q1 and the base of the third transistor Q3. The collector of the first transistor Q1 is connected to the 12V voltage terminal. The emitter of the first transistor Q1 is connected to the gate of the MOSFET Q4 through the fourth resistor R4. The emitter of the third transistor Q3 is connected to the gate of the MOSFET Q4 through the fifth resistor R5. The drain of the MOSFET Q4 is the PWM signal output. When the isolation device 1 uses an optocoupler, the input port of the optocoupler receives the externally input PWM drive signal. After isolating the signal, it is output through the output port. When the input signal of the isolation optocoupler is low, the output port of the optocoupler is high impedance. Current flows through the base of the second transistor Q2, and the second transistor Q2 is turned on. The collector voltage of the second transistor Q2 is pulled low, the base current of the first transistor Q1 is cut off, and the first transistor Q1 is cut off. Current flows through the base of the third transistor Q3, and the third transistor Q3 is turned on. The emitter level of the third transistor Q3 is pulled low, and the gate level of the driven MOSFET Q4 is also pulled low, and the MOSFET Q4 is cut off. At the same time, the level of the second pin of the first capacitor C1 is pulled low to close to 0V. Current flows into the first capacitor C1 through the first diode V1, charging the voltage of the first pin of the first capacitor C1 to about 11.3V. When the input signal of the isolation optocoupler 1 is high, the output port of the optocoupler is pulled low, the current flowing through the base of the second transistor Q2 is cut off, the second transistor Q2 is cut off, the collector voltage level of the second transistor Q2 is pulled up by the second resistor R2, the base voltages of the first transistor Q1 and the third transistor Q3 are pulled up, the first transistor Q1 is turned on, the third transistor Q3 is turned off, the emitter level of the first transistor Q1 is pulled up to 11.3V, the voltage at the second pin of the first capacitor C1 increases simultaneously, the voltage at the first pin of the first capacitor C1 increases, the current flowing through the base of the first transistor Q1 is larger, making the first transistor Q1 turn on faster, and the gate level of the driven MOSFET Q4 is also pulled up faster, and the MOSFET Q4 turns on quickly.

[0006] Furthermore, when the isolation device 1 uses a signal transformer, if the input signal of the signal transformer is low and the transformer output voltage is 0V, the current flowing through the base of the second transistor Q2 increases, the second transistor Q2 turns on, the collector voltage of the second transistor Q2 is pulled low, the base current of the first transistor Q1 is cut off, the first transistor Q1 is cut off, current flows through the base of the third transistor Q3, the third transistor Q3 turns on, the emitter level of the third transistor Q3 is pulled low, the gate level of the driven MOSFET Q4 is also pulled low, the MOSFET Q4 is cut off, at the same time, the level of the second pin of the first capacitor C1 is pulled low to close to 0V, the current flows into the first capacitor C1 through the first diode V1, charging the voltage of the first pin of the first capacitor C1 to about 11.3V; When the input signal of the signal transformer of isolation device 1 is high, the output port of the signal transformer becomes negative. The current flowing through the base of the second transistor Q2 is cut off, and the second transistor Q2 is turned off. The collector voltage level of the second transistor Q2 is pulled up by the second resistor R2. The base voltages of the first transistor Q1 and the third transistor Q3 are pulled up. The first transistor Q1 is turned on, and the third transistor Q3 is turned off. The emitter level of the first transistor Q1 is pulled up to 11.3V. At the same time, the voltage at the second pin of the first capacitor C1 increases. The voltage at the first pin of the first capacitor C1 increases, and the current flowing through the base of the first transistor Q1 is larger, making the first transistor Q1 turn on faster. The gate level of the driven MOSFET Q4 is also pulled up faster, and the MOSFET Q4 turns on quickly.

[0007] Furthermore, the circuit also includes a third resistor R3, through which the cathode of the optocoupler LED is grounded.

[0008] The beneficial effects of this invention are as follows: This invention uses a high-speed optocoupler or signal transformer to replace the digital isolator. The high-speed optocoupler has an extremely high signal isolation voltage, and the high-speed optocoupler transmits signals with strong anti-interference ability. This invention uses discrete device driver modules to replace integrated isolation driver chips. The discrete device driver modules achieve driving through transistors. The discrete driver circuits have high reliability and greatly reduce circuit costs. Attached Figure Description

[0009] Figure 1 This is a structural diagram of a high-voltage isolation drive circuit using optocoupler isolation provided in an embodiment of the present invention.

[0010] Figure 2 This is a structural diagram of a high-voltage isolation drive circuit using signal transformer isolation provided in an embodiment of the present invention. Detailed Implementation

[0011] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0012] This invention provides a high-voltage isolation drive circuit, such as... Figure 1 As shown, the device includes an isolation device 1, a discrete device driving circuit 2, and a driven device 3. The isolation device 1 includes an input section and an output section. The discrete device driving circuit 2 includes a first transistor Q1, a second transistor Q2, a third transistor Q3, a first resistor R1, a second resistor R2, a fourth resistor R4, a fifth resistor R5, a first capacitor C1, and a first diode V1. The driven device 3 includes a MOSFET Q4. The isolation device receives an externally input PWM drive signal. The positive terminal of the input section of the isolation device is connected to the signal input, and the negative terminal of the input section is grounded. The output port of the isolation device is connected to the base of the second transistor Q2. The base of transistor Q2 is connected to the 12V voltage terminal through the first resistor R1 and to the anode of the first diode V1. The cathode of the first diode V1 is connected to the emitter of the first transistor Q1 through the first capacitor C1. The cathode of the first diode V1 is also connected to the collector of the second transistor Q2 through the second resistor R2. The collector of the second transistor Q2 is also connected to the base of the first transistor Q1 and the base of the third transistor Q3. The collector of the first transistor Q1 is connected to the 12V voltage terminal. The emitter of the first transistor Q1 is connected to the gate of the MOSFET Q4 through the fourth resistor R4. The emitter of the third transistor Q3 is connected to the gate of the MOSFET Q4 through the fifth resistor R5. The drain of the MOSFET Q4 is the PWM signal output. Isolation device 1 uses an optocoupler. The input port of the optocoupler receives the externally input PWM drive signal, isolates the signal, and outputs it through the output port. When the input signal of the isolation optocoupler is low, the output port of the optocoupler is high impedance, and the current flows through the base of the second transistor Q2, turning on the second transistor Q2. The collector voltage of the second transistor Q2 is pulled low, the base current of the first transistor Q1 is cut off, and the first transistor Q1 is cut off. The base of the third transistor Q3 has current flowing through it, turning on the third transistor Q3. The emitter level of the third transistor Q3 is pulled low, and the gate level of the driven MOSFET Q4 is also pulled low, turning off the MOSFET Q4. At the same time, the level of the second pin of the first capacitor C1 is pulled low to close to 0V, and the current flows into the first capacitor C1 through the first diode V1, charging the voltage of the first pin of the first capacitor C1 to about 11.3V. When the input signal of optocoupler 1 is high, the output port of optocoupler is pulled low, the current flowing through the base of the second transistor Q2 is cut off, the second transistor Q2 is cut off, the collector voltage level of the second transistor Q2 is pulled up by the second resistor R2, the base voltages of the first transistor Q1 and the third transistor Q3 are pulled up, the first transistor Q1 is turned on, the third transistor Q3 is cut off, the emitter level of the first transistor Q1 is pulled up to 11.3V, the voltage at the second pin of the first capacitor C1 increases simultaneously, the voltage at the first pin of the first capacitor C1 increases, the current flowing through the base of the first transistor Q1 is larger, making the first transistor Q1 turn on faster, and the gate level of the driven MOSFET Q4 is also pulled up faster, and the MOSFET Q4 turns on quickly.

[0013] like Figure 2 As shown, when isolation device 1 uses a signal transformer, if the input signal of the signal transformer is low and the transformer output voltage is 0V, the current flowing through the base of the second transistor Q2 increases, the second transistor Q2 turns on, the collector voltage of the second transistor Q2 is pulled low, the base current of the first transistor Q1 is cut off, the first transistor Q1 is cut off, current flows through the base of the third transistor Q3, the third transistor Q3 turns on, the emitter level of the third transistor Q3 is pulled low, the gate level of the driven MOSFET Q4 is also pulled low, the MOSFET Q4 is cut off, at the same time, the level of the second pin of the first capacitor C1 is pulled low to close to 0V, the current flows into the first capacitor C1 through the first diode V1, charging the voltage of the first pin of the first capacitor C1 to about 11.3V; When the input signal of the signal transformer of isolation device 1 is high, the output port of the signal transformer becomes negative. The current flowing through the base of the second transistor Q2 is cut off, and the second transistor Q2 is turned off. The collector voltage level of the second transistor Q2 is pulled up by the second resistor R2. The base voltages of the first transistor Q1 and the third transistor Q3 are pulled up. The first transistor Q1 is turned on, and the third transistor Q3 is turned off. The emitter level of the first transistor Q1 is pulled up to 11.3V. At the same time, the voltage at the second pin of the first capacitor C1 increases. The voltage at the first pin of the first capacitor C1 increases, and the current flowing through the base of the first transistor Q1 is larger, making the first transistor Q1 turn on faster. The gate level of the driven MOSFET Q4 is also pulled up faster, and the MOSFET Q4 turns on quickly.

[0014] Specifically, the circuit also includes a third resistor R3. The cathode of the light-emitting diode of the isolation optocoupler is grounded through the third resistor R3. The isolation optocoupler is a high-speed optocoupler, which can be HCPL0601 or other high-speed optocouplers.

[0015] Specifically, the signal transformer can be a self-made one or a standard model transformer with a 1:1 turns ratio.

[0016] Specifically, Q1 and Q2 are 9012 or other general-purpose NPN transistors, and Q3 is 9013 or other general-purpose PNP transistors.

[0017] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A high-voltage isolation drive circuit, characterized in that, The device includes an isolation device (1), a discrete device driving circuit (2), and a driven device (3). The isolation device (1) includes an input section and an output section. The discrete device driving circuit (2) includes a first transistor (Q1), a second transistor (Q2), a third transistor (Q3), a first resistor (R1), a second resistor (R2), a fourth resistor (R4), a fifth resistor (R5), a first capacitor (C1), and a first diode (V1). The driven device (3) includes a MOSFET (Q4). The isolation device receives an externally input PWM drive signal. The positive terminal of the input section of the isolation device is connected to the signal input, and the negative terminal of the input section is grounded. The output port of the isolation device is connected to the base of the second transistor (Q2). The base of the transistor is connected to the 12V voltage terminal through the first resistor (R1) and to the anode of the first diode (V1). The cathode of the first diode (V1) is connected to the emitter of the first transistor (Q1) through the first capacitor (C1). The cathode of the first diode (V1) is also connected to the collector of the second transistor (Q2) through the second resistor (R2). The collector of the second transistor (Q2) is also connected to the base of the first transistor (Q1) and the base of the third transistor (Q3). The collector of the first transistor (Q1) is connected to the 12V voltage terminal. The emitter of the first transistor (Q1) is connected to the gate of the MOSFET (Q4) through the fourth resistor (R4). The emitter of the third transistor (Q3) is connected to the gate of the MOSFET (Q4) through the fifth resistor (R5). The drain of the MOSFET (Q4) is the PWM signal output. When the isolation device (1) uses an optocoupler, the input port of the optocoupler receives the external input PWM drive signal, isolates the signal, and outputs it through the output port. When the input signal of the isolation optocoupler is low, the output port of the optocoupler is high impedance, the current flows through the base of the second transistor (Q2), the second transistor (Q2) is turned on, the collector voltage of the second transistor (Q2) is pulled low, the base current of the first transistor (Q1) is cut off, the first transistor (Q1) is cut off, the base of the third transistor (Q3) has current flowing through it, the third transistor (Q3) is turned on, the emitter level of the third transistor (Q3) is pulled low, the gate level of the driven MOS transistor (Q4) is also pulled low, the MOS transistor (Q4) is cut off, at the same time, the level of the second pin of the first capacitor (C1) is pulled low to close to 0V, the current flows into the first capacitor (C1) through the first diode (V1), and charges the voltage of the first pin of the first capacitor (C1) to 11.3V; When the input signal of the isolation optocoupler 1 is high, the output port of the optocoupler is pulled low, the current flowing through the base of the second transistor (Q2) is cut off, the second transistor (Q2) is cut off, the collector voltage level of the second transistor (Q2) is pulled up by the second resistor (R2), the base voltages of the first transistor (Q1) and the third transistor (Q3) are pulled up, the first transistor (Q1) is turned on, the third transistor (Q3) is cut off, the emitter level of the first transistor (Q1) is pulled up to 11.3V, the voltage at the second pin of the first capacitor (C1) increases simultaneously, the voltage at the first pin of the first capacitor (C1) increases, the current flowing through the base of the first transistor (Q1) is larger, making the first transistor (Q1) turn on faster, and the gate level of the driven MOSFET (Q4) is also pulled up faster, and the MOSFET (Q4) turns on quickly.

2. The high-voltage isolation drive circuit according to claim 1, characterized in that, When the isolation device (1) uses a signal transformer, the input signal of the signal transformer is low level, the output voltage of the transformer is 0V, the current flowing through the base of the second transistor (Q2) increases, the second transistor (Q2) is turned on, the collector voltage of the second transistor (Q2) is pulled low, the base current of the first transistor (Q1) is cut off, the first transistor (Q1) is cut off, the base of the third transistor (Q3) has current flowing through it, the third transistor (Q3) is turned on, the emitter level of the third transistor (Q3) is pulled low, the gate level of the driven MOS transistor (Q4) is also pulled low, the MOS transistor (Q4) is cut off, at the same time, the level of the second pin of the first capacitor (C1) is pulled low to close to 0V, the current flows into the first capacitor (C1) through the first diode (V1), charging the voltage of the first pin of the first capacitor (C1) to 11.3V; When the input signal to the transformer is high, the output port of the signal transformer becomes negative. The current flowing through the base of the second transistor (Q2) is cut off, and the second transistor (Q2) is turned off. The collector voltage level of the second transistor (Q2) is pulled up by the second resistor (R2). The base voltages of the first transistor (Q1) and the third transistor (Q3) are pulled up. The first transistor (Q1) turns on, and the third transistor (Q3) turns off. The emitter voltage of the first transistor (Q1) is pulled up to 11.3V. At the same time, the voltage at the second pin of the first capacitor (C1) increases. The voltage at the first pin of the first capacitor (C1) increases, and the current flowing through the base of the first transistor (Q1) is larger, making the first transistor (Q1) turn on faster. The gate voltage of the driven MOSFET (Q4) is also pulled up faster, and the MOSFET (Q4) turns on quickly.

3. The high-voltage isolation drive circuit according to claim 1, characterized in that, The circuit also includes a third resistor (R3), through which the cathode of the optocoupler's light-emitting diode is grounded.

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