High-voltage power supply anti-reverse connection and slow start circuit based on optical coupling isolation

Abstract

This invention discloses a high-voltage power supply reverse connection protection and soft-start circuit based on optocoupler isolation. It consists of an auxiliary source circuit, a reverse connection protection MOSFET module, a soft-start MOSFET module, a fast discharge circuit, and an optocoupler isolation module. The auxiliary source provides the drive voltage to the MOSFETs. Q1 achieves low-loss current conduction for reverse connection protection. Q2 achieves soft start by adjusting the Miller level length through Rsoft and Csoft. The optocoupler isolates the control signal from the high-voltage circuit. The fast discharge circuit enables rapid turn-off of Q2 and protects the MOSFETs. This invention features high integration, low conduction loss, high safety, flexible control, and strong device versatility. It can be widely used in high-voltage power supply systems such as industrial high-voltage power supplies, new energy power supply modules, and airborne high-voltage power supplies, and has good industrialization prospects.

Description

Technical Field

[0001] This invention relates to the field of high-voltage power supply circuit protection technology, specifically a high-voltage power supply reverse connection protection and soft-start circuit based on optocoupler isolation. Background Technology

[0002] In fields such as industrial high-voltage power supplies, new energy power supply modules, and airborne power supplies, reverse polarity connection at the power input terminal is prone to occur, which can directly burn out core circuit components. Simultaneously, surge currents are generated during power-on startup, leading to overcurrent damage to components. However, existing circuits often employ independent designs for reverse polarity protection and soft-start functionality, which have the following drawbacks:

[0003] Traditional high-voltage reverse connection protection circuits mostly use diodes, which have high conduction losses and are not suitable for high-voltage, high-current scenarios.

[0004] Many soft-start circuits lack isolation design, with control signals directly connected to high-voltage circuits, posing electromagnetic interference and safety hazards. Furthermore, many soft-start circuits lack isolating switch control functionality and fast discharge capability, which negatively impacts the robustness of the MOSFET.

[0005] Existing integrated circuits lack dedicated discharge circuits when MOSFETs are turned off. Residual charge causes the MOSFET to pass through a variable resistance region for an extended period during the turn-off process, generating transient heat that can easily lead to thermal breakdown of the MOSFET and a short lifespan.

[0006] The independent design of the drive power supply for the reverse connection protection and soft start circuit increases the circuit size and cost, and results in low integration. Summary of the Invention

[0007] The purpose of this invention is to provide a high-voltage power supply reverse connection protection and soft start circuit based on optocoupler isolation, including an auxiliary power supply circuit, a reverse connection protection MOSFET module, a soft start MOSFET module, a fast discharge circuit, and an optocoupler isolation module;

[0008] The auxiliary power circuit provides drive voltage for the reverse connection protection MOSFET module and the soft-start MOSFET module;

[0009] When the auxiliary source circuit is working, the reverse connection protection MOSFET module is turned on to achieve low-loss current conduction;

[0010] The soft-start MOSFET module is used to limit current and achieve soft start of the power supply;

[0011] The fast discharge circuit is used to discharge residual charge on the gate of the reverse-connection MOS transistor module.

[0012] The optocoupler isolation module is used to achieve electrical isolation between the control signal and the high-voltage circuit, and to control the on / off state of the fast discharge circuit.

[0013] Furthermore, the auxiliary source circuit includes a resistor and a Zener diode connected in series;

[0014] One end of the resistor is connected to the positive input terminal of the power supply system, and the other end is connected to the cathode of the Zener diode, while the anode of the Zener diode is grounded.

[0015] The auxiliary power source circuit is connected in series between the positive input terminal and the negative input terminal of the power supply system.

[0016] Furthermore, the reverse polarity protection MOSFET module includes an N-MOSFET Q1;

[0017] The drain of the N-MOS transistor Q1 is connected to the negative input terminal of the power supply system, and the source is connected to the common S network of the power supply system.

[0018] Furthermore, when the auxiliary source circuit is not working, the N-MOS transistor Q1 of the reverse polarity protection MOS transistor module relies on the body diode for current flow.

[0019] Furthermore, the soft-start MOS transistor module includes an N-MOS transistor Q2;

[0020] The drain of the N-MOS transistor Q2 is connected to the negative output terminal of the power supply system, and the source is connected to the common S network of the power supply system.

[0021] A resistor Rsoft and a capacitor Csoft are connected between the gate and drain of the N-MOS transistor Q2. One end of the resistor Rsoft is connected to the gate of the N-MOS transistor Q2, and the other end is connected to one end of the capacitor Csoft. The other end of the capacitor Csoft is connected to the drain of the N-MOS transistor Q2.

[0022] Furthermore, the fast discharge circuit includes a PNP transistor and resistors and capacitors;

[0023] The fast discharge circuit is electrically connected to the gate of N-MOS transistor Q2 and is used to discharge the residual charge on the gate of N-MOS transistor Q2.

[0024] Furthermore, the optocoupler isolation module includes an optocoupler U1; the optocoupler U1 is electrically connected to the control terminal and the fast discharge circuit respectively.

[0025] Furthermore, when the control terminal is at a low level, the output of optocoupler U1 is cut off; when the control terminal is at a high level, optocoupler U1 is turned on.

[0026] Furthermore, when the control terminal is at a low level, the fast discharge circuit is turned on; when the control terminal is at a high level, the output of the fast discharge circuit is turned off.

[0027] Furthermore, the high-voltage power supply reverse connection protection and soft start circuit works as follows: after the system is powered on, the auxiliary power supply circuit starts, and the reverse connection protection MOS transistor module automatically turns on to achieve reverse connection protection;

[0028] When the control terminal is high, the optocoupler isolation module is turned on, the fast discharge circuit is turned off, and the soft-start MOSFET module achieves soft start and remains on.

[0029] When the control terminal is at a low level, the optocoupler isolation module is turned off, the fast discharge circuit is turned on, the soft-start MOSFET module is turned off, and the power supply stops supplying power to the load.

[0030] The technical effects of this invention are undeniable, and it has the following significant beneficial effects:

[0031] 1. High degree of integration: It integrates reverse connection protection, soft start, fast shutdown, device protection, and optocoupler isolation functions into one circuit, which simplifies the circuit structure, reduces the size, and lowers the hardware cost;

[0032] 2. Low conduction loss: N-MOS transistors are used to replace traditional diodes to prevent reverse connection. The MOS transistors are fully turned on under the drive of the auxiliary source, and the current loss is much lower than that of diodes, making it suitable for high voltage and high current scenarios.

[0033] 3. High safety: The control signal is electrically isolated from the high-voltage circuit through optocouplers, avoiding electromagnetic interference and high voltage interference to the control terminal. At the same time, the fast discharge circuit protects the MOSFET from thermal breakdown when turned off, improving the reliability and service life of the circuit.

[0034] 4. Flexible control: The reverse connection protection function takes effect automatically upon power-on, and the soft start function is controlled by the control terminal level. The power supply can be flexibly controlled to start and stop according to the actual application scenario, and it is compatible with a variety of high-voltage power supply systems.

[0035] 5. High versatility of components: The core components of the circuit are conventional resistors, capacitors, MOSFETs, optocouplers, transistors, and Zener diodes. The components are readily available, the wiring is simple, and it is easy to carry out industrial production and promotion. Attached Figure Description

[0036] Figure 1 This is an overall block diagram of the circuit system of the present invention;

[0037] Figure 2 This is the circuit schematic diagram of the present invention;

[0038] Figure 3 Measured waveforms (CH1: Slow-start MOS Vgs waveform; CH2: Slow-start MOS Vds waveform; CH4: Slow-start MOS Ids waveform). Detailed Implementation

[0039] The present invention will be further described below with reference to embodiments, but it should not be construed that the scope of the present invention is limited to the following embodiments. Various substitutions and modifications made based on ordinary technical knowledge and common practices in the art without departing from the above-described technical concept of the present invention should be included within the scope of protection of the present invention.

[0040] Example 1:

[0041] A high-voltage power supply reverse connection protection and soft start circuit based on optocoupler isolation includes an auxiliary power supply circuit, a reverse connection protection MOSFET module, a soft start MOSFET module, a fast discharge circuit, and an optocoupler isolation module.

[0042] The auxiliary power circuit provides drive voltage for the reverse connection protection MOSFET module and the soft-start MOSFET module;

[0043] When the auxiliary source circuit is working, the reverse connection protection MOSFET module is turned on to achieve low-loss current conduction;

[0044] The soft-start MOSFET module is used to limit current and achieve soft start of the power supply;

[0045] The fast discharge circuit is used to discharge residual charge on the gate of the reverse-connection MOS transistor module.

[0046] The optocoupler isolation module is used to achieve electrical isolation between the control signal and the high-voltage circuit, and to control the on / off state of the fast discharge circuit.

[0047] Example 2:

[0048] A high-voltage power supply reverse connection protection and soft start circuit based on optocoupler isolation, with the same technical content as Embodiment 1, further wherein the auxiliary source circuit includes a resistor and a Zener diode connected in series.

[0049] One end of the resistor is connected to the positive input terminal of the power supply system, and the other end of the resistor is connected to the cathode of the Zener diode. The anode of the Zener diode is grounded, thus forming an auxiliary power supply to ground at the cathode of the Zener diode.

[0050] The auxiliary power source circuit is connected in series between the positive input terminal and the negative input terminal of the power supply system.

[0051] Example 3:

[0052] A high-voltage power supply reverse connection protection and soft start circuit based on optocoupler isolation, with the same technical content as any one of embodiments 1-2, further wherein the reverse connection protection MOS transistor module includes an N-MOS transistor Q1;

[0053] The drain of the N-MOS transistor Q1 is connected to the negative input terminal of the power supply system, and the source is connected to the common S network of the power supply system.

[0054] Example 4:

[0055] A high-voltage power supply reverse connection protection and soft start circuit based on optocoupler isolation, with the same technical content as any one of embodiments 1-3, further wherein when the auxiliary source circuit is not working, the N-MOS transistor Q1 of the reverse connection protection MOS transistor module relies on the body diode for current flow.

[0056] Example 5:

[0057] A high-voltage power supply reverse connection protection and soft start circuit based on optocoupler isolation, with the same technical content as any one of embodiments 1-4, further wherein the soft start MOS transistor module includes an N-MOS transistor Q2;

[0058] The drain of the N-MOS transistor Q2 is connected to the negative output terminal of the power supply system, and the source is connected to the common S network of the power supply system.

[0059] A resistor Rsoft and a capacitor Csoft are connected between the gate and drain of the N-MOS transistor Q2. One end of the resistor Rsoft is connected to the gate of the N-MOS transistor Q2, and the other end is connected to one end of the capacitor Csoft. The other end of the capacitor Csoft is connected to the drain of the N-MOS transistor Q2.

[0060] Example 6:

[0061] A high-voltage power supply reverse connection protection and soft start circuit based on optocoupler isolation, with the same technical content as any one of embodiments 1-5, further wherein the fast discharge circuit includes a PNP transistor and resistors and capacitors;

[0062] The fast discharge circuit is electrically connected to the gate of N-MOS transistor Q2 and is used to discharge the residual charge on the gate of N-MOS transistor Q2.

[0063] Example 7:

[0064] A high-voltage power supply reverse connection protection and soft start circuit based on optocoupler isolation, with the same technical content as any one of embodiments 1-6, further wherein the optocoupler isolation module includes an optocoupler U1; the optocoupler U1 is electrically connected to the control terminal and the fast discharge circuit respectively.

[0065] Example 8:

[0066] A high-voltage power supply reverse connection protection and soft start circuit based on optocoupler isolation, with the same technical content as any one of embodiments 1-7, further wherein when the control terminal is low level, the output of optocoupler U1 is cut off; when the control terminal is high level, optocoupler U1 is turned on.

[0067] Example 9:

[0068] A high-voltage power supply reverse connection protection and soft start circuit based on optocoupler isolation, with the same technical content as any one of embodiments 1-8, further wherein when the control terminal is at a low level, the fast discharge circuit is turned on; when the control terminal is at a high level, the output of the fast discharge circuit is turned off.

[0069] Example 10:

[0070] A high-voltage power supply reverse connection protection and soft start circuit based on optocoupler isolation, with the same technical content as any one of embodiments 1-9. Further, the high-voltage power supply reverse connection protection and soft start circuit works as follows: after the system is powered on, the auxiliary power supply circuit starts, and the reverse connection protection MOS transistor module is automatically turned on to realize reverse connection protection.

[0071] When the control terminal is high, the optocoupler isolation module is turned on, the fast discharge circuit is turned off, and the soft-start MOSFET module achieves soft start and remains on.

[0072] When the control terminal is at a low level, the optocoupler isolation module is turned off, the fast discharge circuit is turned on, the soft-start MOSFET module is turned off, and the power supply stops supplying power to the load.

[0073] Example 11:

[0074] A high-voltage power supply reverse connection protection and soft start circuit based on optocoupler isolation consists of five parts: an auxiliary power supply circuit, a reverse connection protection MOSFET module, a soft start MOSFET module, a fast discharge circuit, and an optocoupler isolation module. The modules are electrically connected to form an integrated high-voltage power supply protection circuit.

[0075] For the circuit diagram of the high-voltage power supply reverse connection protection and soft start circuit, please refer to [link / reference]. Figure 2 When setting up the high-voltage power supply reverse connection protection and soft start circuit, Figure 2 The equivalent of resistor R15, switch Q4, switch Q6, and switch Q7 is: Figure 1 Q1 in the middle; will Figure 2 D1, U3, C1, R1-R4 in the equation are equivalent to Figure 1 The auxiliary source circuit in; Figure 2 D3, R6, R7, and Q5 in the equation are equivalent to: Figure 1 The fast discharge circuit in the middle. Figure 2 C2, Q1-Q3, R8, R12, and R13 are equivalent to Figure 1 Q2 in the text.

[0076] The specific structure of the high-voltage power supply reverse connection protection and soft start circuit is as follows:

[0077] 1. Auxiliary source circuit

[0078] Connected in series between the positive and negative terminals of the power supply, it consists of a series resistor and a Zener diode, providing drive voltage for the reverse connection protection MOSFET module and the soft-start MOSFET module; preferably, 12V is used as the drive voltage, and the core component is a 12V Zener diode, which is adapted to the drive characteristics of N-MOSFETs to ensure stable conduction of the MOSFETs.

[0079] 2. Reverse polarity protected MOSFET module

[0080] The core component is an N-MOS transistor Q1. The drain of Q1 is connected to the negative terminal VIN- network of the power supply system input, and the source is connected to the common terminal S network of the system. When the circuit is not working, current flows through the body diode of Q1. After the auxiliary source circuit is working, Q1 is fully turned on, achieving low-loss current flow.

[0081] 3. Soft-start MOSFET module

[0082] The core component is an N-MOS transistor Q2. The drain of Q2 is connected to the negative terminal Vout- network of the power supply system output, and the source is connected to the common terminal S network of the system. The gate and drain of Q2 are connected in parallel with an Rsoft resistor and a Csoft capacitor. By adjusting the Miller level of Q2 gate charging, the current during the turn-on process of Q2 is limited, thus achieving a soft start. The switching on and off of Q2 is controlled by an optocoupler isolation module and a fast discharge circuit.

[0083] 4. Fast Discharge Circuit

[0084] Composed of a PNP transistor and resistors and capacitors, it automatically generates bias according to the input voltage. When the control terminal is low, the circuit turns on, discharging the residual charge on the gate of Q2 to the S network, thus achieving rapid turn-off of Q2. When the control terminal is high, the circuit turns off, without affecting the soft-start process. This circuit can reduce the operating time of the variable resistor during the turn-off process of Q2, protecting Q2 from thermal breakdown.

[0085] 5. Optical isolation module

[0086] The core component is the optocoupler U1, which provides electrical isolation between the control signal and the high-voltage circuit to avoid electromagnetic interference. When the control terminal is low, the optocoupler U1 output is cut off, and the fast discharge circuit operates. When the control terminal is high, the optocoupler U1 is turned on, and the fast discharge circuit is reverse biased and stops operating.

[0087] The operating logic of this circuit is as follows: After the system is powered on, the auxiliary power supply circuit starts, the reverse connection protection MOSFET module automatically turns on, and the reverse connection protection function takes effect; when the control terminal inputs a high level, the optocoupler isolation module turns on, the fast discharge circuit turns off, the Rsoft resistor and Csoft capacitor of the slow-start MOSFET module slowly charge, Q2 gradually turns on, realizing the power supply slow start, and finally maintaining a fully open state; when the control terminal inputs a low level, the optocoupler isolation module turns off, the fast discharge circuit quickly turns on, discharges the residual charge on the gate of Q2, Q2 quickly turns off, and the power system completely stops supplying power to the load.

[0088] The scope of protection of this invention is not limited to the above embodiments. The selection of devices can be adjusted according to the voltage and current requirements of the actual high-voltage power supply system. For example, the Zener diode can be selected with specifications such as 9V or 15V, the MOSFET can be selected with a model that is adapted to higher voltage, and the parameters of the Rsoft resistor and Csoft capacitor can be adjusted according to the soft start current requirements. All equivalent substitutions or improvements made based on the technical solution of this invention fall within the scope of protection of this invention.

Claims

1. A high-voltage power supply reverse connection protection and soft-start circuit based on optocoupler isolation, characterized in that, Includes auxiliary power supply circuit, reverse polarity protection MOSFET module, soft-start MOSFET module, fast discharge circuit, and optocoupler isolation module; The auxiliary power circuit provides drive voltage for the reverse connection protection MOSFET module and the soft-start MOSFET module; When the auxiliary source circuit is working, the reverse connection protection MOSFET module is turned on to achieve low-loss current conduction; The soft-start MOSFET module is used to limit current and achieve soft start of the power supply; The fast discharge circuit is used to discharge residual charge on the gate of the reverse-connection MOS transistor module. The optocoupler isolation module is used to achieve electrical isolation between the control signal and the high-voltage circuit, and to control the on / off state of the fast discharge circuit.

2. The high-voltage power supply reverse connection protection and soft-start circuit based on optocoupler isolation according to claim 1, characterized in that, The auxiliary source circuit includes a resistor and a Zener diode connected in series; One end of the resistor is connected to the positive input terminal of the power supply system, and the other end is connected to the cathode of the Zener diode, while the anode of the Zener diode is grounded. The auxiliary power source circuit is connected in series between the positive input terminal and the negative input terminal of the power supply system.

3. The high-voltage power supply reverse connection protection and soft-start circuit based on optocoupler isolation according to claim 1, characterized in that, The reverse polarity protection MOSFET module includes an N-MOS transistor Q1; The drain of the N-MOS transistor Q1 is connected to the negative input terminal of the power supply system, and the source is connected to the common S network of the power supply system.

4. The high-voltage power supply reverse connection protection and soft-start circuit based on optocoupler isolation according to claim 3, characterized in that, When the auxiliary source circuit is not working, the N-MOS transistor Q1 of the reverse polarity protection MOS transistor module relies on the body diode for current flow.

5. A high-voltage power supply reverse connection protection and soft-start circuit based on optocoupler isolation according to claim 1, characterized in that, The soft-start MOS transistor module includes an N-MOS transistor Q2; The drain of N-MOS transistor Q2 is connected to the negative output terminal of the power supply system, and the source is connected to the common S network of the power supply system. A resistor Rsoft and a capacitor Csoft are connected between the gate and drain of the N-MOS transistor Q2. One end of the resistor Rsoft is connected to the gate of the N-MOS transistor Q2, and the other end is connected to one end of the capacitor Csoft. The other end of the capacitor Csoft is connected to the drain of the N-MOS transistor Q2.

6. The high-voltage power supply reverse connection protection and soft-start circuit based on optocoupler isolation according to claim 5, characterized in that, The fast discharge circuit includes a PNP transistor and resistors and capacitors; The fast discharge circuit is electrically connected to the gate of N-MOS transistor Q2 and is used to discharge the residual charge on the gate of N-MOS transistor Q2.

7. The high-voltage power supply reverse connection protection and soft-start circuit based on optocoupler isolation according to claim 1, characterized in that, The optocoupler isolation module includes an optocoupler U1; the optocoupler U1 is electrically connected to the control terminal and the fast discharge circuit respectively.

8. A high-voltage power supply reverse connection protection and soft-start circuit based on optocoupler isolation according to claim 7, characterized in that, When the control terminal is low, the output of optocoupler U1 is cut off; when the control terminal is high, optocoupler U1 is turned on.

9. A high-voltage power supply reverse connection protection and soft-start circuit based on optocoupler isolation according to claim 1, characterized in that, When the control terminal is at a low level, the fast discharge circuit is turned on; when the control terminal is at a high level, the fast discharge circuit output is turned off.

10. A high-voltage power supply reverse connection protection and soft-start circuit based on optocoupler isolation according to claim 1, characterized in that, The high-voltage power supply reverse connection protection and soft start circuit works as follows: after the system is powered on, the auxiliary power supply circuit starts, and the reverse connection protection MOS transistor module automatically turns on to achieve reverse connection protection. When the control terminal is high, the optocoupler isolation module is turned on, the fast discharge circuit is turned off, and the soft-start MOSFET module achieves soft start and remains on. When the control terminal is at a low level, the optocoupler isolation module is turned off, the fast discharge circuit is turned on, the soft-start MOSFET module is turned off, and the power supply stops supplying power to the load.

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