Overvoltage protection circuit

Abstract

The utility model discloses a high-voltage isolation detection circuit. The high-voltage isolation detection circuit is characterized by further comprising a voltage detection circuit which is respectively connected with a power supply output circuit and an isolation driving circuit, and the voltage detection circuit comprises an operational amplifier U1A and a resistor R5 connected with the output end power supply and the operational amplifier U1A. The overvoltage protection circuit is a pure hardware overvoltage protection circuit, the output voltage of the power supply is detected through the arrangement of the voltage detection circuit, the power supply is preset to be connected with the negative input end of the operational amplifier U1A, and the resistor R5 is connected with the operational amplifier U1A. Output voltage enters the positive input end of the operational amplifier U1A after being detected and is compared with the negative input end of the operational amplifier U1A, when the voltage of the positive input end of the operational amplifier U1A is smaller than preset voltage, normal is indicated, when the voltage is larger than the preset voltage, overvoltage is indicated, and output can be rapidly cut off; the time used by the circuit is less than 15 microseconds, so that the MOS tube is protected from being broken down by overvoltage, the electronic device is protected, and the circuit has the characteristics of quick response and small damage to the electronic device.

Description

TECHNICAL FIELD

[0001] The utility model relates to new energy automobile technical field, concretely is a kind of overvoltage protection circuit. BACKGROUND

[0002] At present, in the field of new energy vehicles, to meet the safety specifications and strengthen the protection of electronic equipment, more and more electronic equipment needs to increase overvoltage protection circuit, in the existing overvoltage protection circuit, the time used by the software detection circuit of MCU for overvoltage is too long, which will cause the electronic device to be in the state of circuit overvoltage for too long time, and the electronic device is easy to be damaged once in the state of circuit overvoltage for too long time, once the electronic device is damaged, it will cause the entire electronic equipment failure, and our overvoltage protection circuit can turn off the circuit within 15 microseconds through pure hardware to prevent the electronic device from being damaged, therefore, an overvoltage protection circuit is proposed. SUMMARY

[0003] The main purpose of the utility model is to effectively solve the problems in the background art.

[0004] To achieve the above purpose, the technical scheme adopted by the utility model is as follows: an overvoltage protection circuit, including isolation driving circuit, MOS tube driving circuit connected with the isolation driving circuit, power output circuit connected with the MOS tube driving circuit, characterized in that: it further includes voltage detection circuit connected with the power output circuit and the isolation driving circuit respectively; the voltage detection circuit includes operational amplifier U1A, resistor R5 connected with the output end power supply and connected with the operational amplifier U1A, resistor R7 connected with the resistor R5, resistor R4, and the resistor R7 is grounded, resistor R8 connected with the operational amplifier U1A, capacitor C8, resistor R6, 3.3V power supply end connected with the resistor R6, and the capacitor C8, resistor R8, operational amplifier U1A are grounded, 12V power supply end connected with the operational amplifier U1A, resistor R4, diode D3 connected with the operational amplifier U1A, isolation driving circuit connected with the diode D3.

[0005] Preferably, the MOS tube driving circuit comprises MOS tube Q1, MOS tube Q2 connected with MOS tube Q1, diode D2 connected with the isolation driving circuit and connected with MOS tube Q1, resistance R1, resistance R2 connected with diode D2, resistance R2 connected with MOS tube Q1, capacitor C5, resistance R3, resistance R3 connected with capacitor C5, MOS tube Q1 and the isolation driving circuit, MOS tube Q2, capacitor C3, capacitor C4, capacitor C9, capacitor C10, capacitor C1 connected with capacitor C3, capacitor C2 connected with capacitor C4, capacitor C1 connected with capacitor C2, MOS tube Q1, VIN power supply end, diode D5 connected with the isolation driving circuit, resistance R9, resistance R10 connected with diode D5, resistance R10 connected with resistance R9, capacitor C13, resistance R11 and MOS tube Q1, resistance R11 connected with capacitor C13, MOS tube Q2, capacitor C12, capacitor C11, and capacitor C13, resistance R11, MOS tube Q2, capacitor C12, capacitor C11 are grounded, capacitor C9 connected with capacitor C12, capacitor C10 connected with capacitor C11.

[0006] Preferably, the power output circuit comprises transformer T1, capacitor CX1 connected with the VIN power supply end, capacitor CX2, capacitor CX2 connected with capacitor CX1, capacitor CX3, capacitor CX4 connected with capacitor CX3, inductor L2, transformer T1 connected with inductor L2, current transformer L1 connected with transformer T1, MOS tube driving circuit connected with current transformer L1, diode D1 connected with transformer T1, capacitor EC1 connected with diode D1, capacitor EC2, capacitor C6 and output end power supply, diode D4 connected with transformer T1, capacitor EC3 connected with diode D4, capacitor EC4, output end power supply, and capacitor EC1, capacitor EC2, capacitor EC3, capacitor EC4 are also connected with transformer T1, capacitor C7 connected with capacitor C6, and the transformer T1, capacitor EC1, capacitor EC2, capacitor EC3, capacitor EC4, capacitor C7 are grounded.

[0007] Preferably, the isolation drive circuit comprises an isolation drive U2, an R14 connected with the PWM4A and the isolation drive U2, a capacitor C15 connected with the resistor R14, a resistor R13, a resistor R15 connected with the PWM4B and the isolation drive U2, a capacitor C14 connected with the resistor R15, a resistor R12, and the capacitor C14, the resistor R12, the capacitor C15 and the resistor R13 are grounded, a capacitor C18 connected with the isolation drive U2, a resistor R19, a resistor R18, a voltage detection circuit connected with the resistor R18, a capacitor C18 connected with the resistor R19, and the resistor R19 and the capacitor C18 are grounded, a capacitor C21 connected with the isolation drive U2, a resistor R20, a resistor R20 connected with the capacitor C21, and the capacitor C21 and the resistor R20 are grounded, a capacitor C19 connected with the isolation drive U2, a capacitor C20, a resistor R16, a 3.3V power supply end connected with the resistor R16, a capacitor C20 connected with the capacitor C19, and the capacitor C19 and the capacitor C20 are grounded, a capacitor C16 connected with the isolation drive U2, a diode ZD1, a diode D6, a capacitor C16 connected with the isolation drive U2, a diode ZD1, a MOS tube drive circuit, a capacitor C17 connected with the isolation drive U2, a resistor R17, a diode ZD2 and a diode D6, a capacitor C22 connected with the resistor R17, and a 12V power supply end, the capacitor C17, the diode ZD2, the isolation drive U2, the MOS tube drive circuit connected with the isolation drive U2, and the capacitor C17, the diode ZD2, the isolation drive U2, and the capacitor C22 are grounded.

[0008] The utility model has the following beneficial effects: the circuit is a pure hardware overvoltage protection circuit, the voltage detection circuit is arranged, the power output voltage is detected, a power connection operational amplifier U1A negative input end is preset, the output voltage is detected and enters the operational amplifier U1A positive input end, compares with the operational amplifier U1A negative input end, when the operational amplifier U1A positive input end voltage is less than the preset voltage and indicates normal, is greater than the preset voltage and indicates overvoltage, can quickly shut off the output, the time used is less than 15 microseconds, so as to protect the MOS tube from being overvoltage breakdown, thereby protecting the electronic device, and the utility model has the characteristics of quick response and small electronic device damage;

[0009] The MOS tube drive circuit is arranged, the upper MOS tube and the lower MOS tube are controlled by PWM to drive the transformer.

[0010] The power output circuit is arranged, the transformer is powered on and powered off on both sides, the transformer is reduced in pressure and output, and the effect of output voltage is achieved.

[0011] Through the setting of the isolation driving circuit, the isolation driving circuit is used for converting 3.3V PWM into 12V PWM for driving the MOS to work, and plays an isolation role, the voltage detection circuit output is connected with an isolation driving enable pin, when the enable pin is low, the PWM output is started, when the enable pin is high, the PWM output is closed, and the driving is disconnected to achieve the overvoltage protection of the circuit. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 is a principle block diagram of the utility model;

[0013] Figure 2 is a circuit diagram of the MOS driving circuit of the utility model;

[0014] Figure 3 is a circuit diagram of the power output circuit of the utility model;

[0015] Figure 4 is a circuit diagram of the voltage detection circuit of the utility model;

[0016] Figure 5 is a circuit diagram of the isolation driving circuit of the utility model.

[0017] Legend: 1, MOS driving circuit; 2, power output circuit; 3, voltage detection circuit; 4, isolation driving circuit. DETAILED DESCRIPTION

[0018] In order to make the technical means, creative features, purposes and effects of the utility model easy to understand, the utility model is further described below in combination with specific embodiments.

[0019] As Figures 1-5As shown, an overvoltage protection circuit, comprising an isolation drive circuit 4, a MOS tube drive circuit 1 connected with the isolation drive circuit 4, a power output circuit 2 connected with the MOS tube drive circuit 1, characterized in that: further comprising a voltage detection circuit 3 connected with the power output circuit 2 and the isolation drive circuit 4 respectively; the voltage detection circuit 3 comprises an operational amplifier U1A, a resistor R5 connected with an output power supply and the operational amplifier U1A, a resistor R7 connected with the resistor R5, a resistor R4, and the resistor R7 is grounded, a resistor R8, a capacitor C8, a resistor R6 connected with the operational amplifier U1A, a 3.3V power supply end connected with the resistor R6, and the capacitor C8, the resistor R8, the operational amplifier U1A are grounded, a 12V power supply end connected with the operational amplifier U1A, a resistor R4, a diode D3 connected with the operational amplifier U1A, and the isolation drive circuit 4 connected with the diode D3; the circuit is a pure hardware overvoltage protection circuit, through the setting of the voltage detection circuit 3, the output voltage of the power supply is detected, a negative input end of the operational amplifier U1A connected with the power supply is preset, after the output voltage is detected, the positive input end of the operational amplifier U1A is entered, and the negative input end of the operational amplifier U1A is compared, when the voltage of the positive input end of the operational amplifier U1A is less than the preset voltage, it indicates normal, and when it is greater than the preset voltage, it indicates overvoltage, and the output can be quickly turned off; the time used is less than 15 microseconds, so as to protect the MOS tube from being broken down by overvoltage, thereby protecting the electronic device, and the circuit has the characteristics of fast response and small damage to the electronic device.

[0020] In one embodiment, the MOS tube drive circuit 1 comprises a MOS tube Q1, a MOS tube Q2 connected with the MOS tube Q1, a diode D2 connected with the isolation drive circuit 4 and the MOS tube Q1, a resistor R1, a resistor R2 connected with the diode D2, a resistor R2 connected with the MOS tube Q1, a capacitor C5, a resistor R3, a capacitor C3 connected with the resistor R3, the MOS tube Q1 and the isolation drive circuit 4, the MOS tube Q2, a capacitor C4, a capacitor C9, a capacitor C10, a capacitor C1 connected with the capacitor C3, a capacitor C2 connected with the capacitor C4, a capacitor C1 connected with the capacitor C2, the MOS tube Q1, a VIN power supply end; a diode D5 connected with the isolation drive circuit 4, a resistor R9, a resistor R10 connected with the diode D5, a resistor R10 connected with the resistor R9, a capacitor C13, a resistor R11 and a MOS tube Q1, a resistor R11 connected with the capacitor C13, the MOS tube Q2, a capacitor C12, a capacitor C11, and the capacitor C13, the resistor R11, the MOS tube Q2, the capacitor C12, the capacitor C11 are grounded, a capacitor C9 connected with the capacitor C12, a capacitor C10 connected with the capacitor C11; through the setting of the MOS tube drive circuit 1, the upper MOS tube and the lower MOS tube are controlled to work by PWM, so as to drive the transformer.

[0021] In one embodiment, the power output circuit 2 comprises a transformer T1, a capacitor CX1 connected to the VIN power supply end, a capacitor CX2, a capacitor CX2 connected to the capacitor CX1, a capacitor CX3, a capacitor CX4, a capacitor CX4 connected to the capacitor CX3, an inductor L2, a transformer T1 connected to the inductor L2, a current transformer L1 connected to the transformer T1, a MOS tube driving circuit 1 connected to the current transformer L1, a diode D1 connected to the transformer T1, a capacitor EC1 connected to the diode D1, a capacitor EC2, a capacitor C6 and an output power supply, a diode D4 connected to the transformer T1, a capacitor EC3 connected to the diode D4, a capacitor EC4, an output power supply, and the capacitor EC1, the capacitor EC2, the capacitor EC3 and the capacitor EC4 are also connected to the transformer T1; a capacitor C7 connected to the capacitor C6; the transformer T1, the capacitor EC1, the capacitor EC2, the capacitor EC3, the capacitor EC4 and the capacitor C7 are grounded; by setting the power output circuit 2, the transformer is powered on and powered off on both sides, the transformer is stepped down, and the output voltage effect is achieved.

[0022] In one embodiment, the isolation drive circuit 4 includes an isolation drive U2, a resistor R14 connected with the PWM4A and connected with the isolation drive U2, a capacitor C15 connected with the resistor R14, a resistor R13, a capacitor C14 connected with the resistor R15 connected with the PWM4B and connected with the isolation drive U2, a resistor R12, and the capacitor C14, the resistor R12, the capacitor C15, the resistor R13 are grounded, a capacitor C18 connected with the isolation drive U2, a resistor R19, a resistor R18, a voltage detection circuit 3 connected with the resistor R18, a capacitor C18 connected with the resistor R19, and the resistor R19, the capacitor C18 are grounded, a capacitor C21 connected with the isolation drive U2, a resistor R20, a resistor R20 connected with the capacitor C21, and the capacitor C21, the resistor R20 are grounded, a capacitor C19, a capacitor C20, a resistor R16 connected with the isolation drive U2, a 3.3V power terminal connected with the resistor R16, a capacitor C20 connected with the capacitor C19, and the capacitor C19, the capacitor C20 are grounded, a capacitor C16 connected with the isolation drive U2, a diode ZD1, a diode D6, a capacitor C16 connected with the isolation drive U2, a diode ZD1, a MOS tube drive circuit 1, a capacitor C17 connected with the isolation drive U2, a resistor R17, a diode ZD2 and a diode D6, a capacitor C22 connected with the resistor R17, a 12V power terminal, the capacitor C17, the diode ZD2, the isolation drive U2, the MOS tube drive circuit 1 connected with the isolation drive U2, the capacitor C17, the diode ZD2, the isolation drive U2, the capacitor C22 are grounded; through the setting of the isolation drive circuit 4, the isolation drive circuit 4 is used for converting 3.3V PWM into 12V PWM for driving MOS work, plays an isolation role, and the voltage detection circuit 3 outputs a connection isolation drive enable pin, when the enable pin is low, the PWM output is turned on, when the enable pin is high, the PWM output is turned off, and the drive is disconnected to achieve overvoltage protection of the circuit.

[0023] The utility model discloses a working principle: isolation drive circuit 4 is connected with MOS pipe drive circuit 1, and MOS pipe drive circuit 1 is used to drive MOS pipe, drives transformer to work, and power output circuit 2 is connected with MOS pipe drive circuit 1, makes transformer work through the control transformer both ends voltage, then rectifies output voltage, voltage detection circuit is connected with 3 power output circuit 2, and a voltage is entered operational amplifier U1A negative input end, and output voltage is divided, enters operational amplifier U1A positive input end, compares with operational amplifier U1A negative input end, when operational amplifier U1A positive input end is less than operational amplifier U1A negative input end, exports 0, when operational amplifier U1A positive input end is greater than operational amplifier U1A negative input end, exports 1, and output control isolation drive enables, isolation drive circuit 4 is connected with voltage detection circuit 3, and isolation drive circuit 4 works through the PWM control MOS pipe drive circuit 1 when receiving voltage detection circuit 3 output 1, closes PWM drive, to reach the purpose of overvoltage cut-off circuit.

[0024] The above shows and describes the basic principle and main features of the utility model and the advantages of the utility model. The skilled person in the art should understand that the utility model is not limited by the above examples, and the above examples and the description in the specification are only to illustrate the principle of the utility model. Without departing from the spirit and scope of the utility model, the utility model can have various changes and improvements, and these changes and improvements all fall within the scope of the claimed utility model. The scope of protection of the utility model is defined by the appended claims and their equivalents.

Claims

1. An overvoltage protection circuit comprising an isolation drive circuit (4), a MOS transistor drive circuit (1) connected to the isolation drive circuit (4), and a power supply output circuit (2) connected to the MOS transistor drive circuit (1), characterized in that: It also includes voltage detection circuit (3) connected with power output circuit (2) and isolation drive circuit (4) respectively; the voltage detection circuit (3) includes operational amplifier U1A, resistance R5 connected with output terminal power supply and connected with operational amplifier U1A, resistance R7 connected with resistance R5, resistance R4, and resistance R7 ground, resistance R8 connected with operational amplifier U1A, capacitor C8, resistance R6, 3.3V power supply end connected with resistance R6, and capacitor C8, resistance R8, operational amplifier U1A ground, 12V power supply end connected with operational amplifier U1A, resistance R4 connected with operational amplifier U1A, diode D3, isolation drive circuit (4) connected with diode D3.

2. The overvoltage protection circuit of claim 1, wherein: The MOS tube drive circuit (1) includes MOS tube Q1, MOS tube Q2 connected with MOS tube Q1, diode D2 connected with isolation drive circuit (4) and connected with MOS tube Q1, resistance R1, resistance R2 connected with diode D2, resistance R2 connected with resistance R1 and connected with MOS tube Q1, capacitor C5, resistance R3, resistance R3 connected with capacitor C5, MOS tube Q1 and isolation drive circuit (4), MOS tube Q2, capacitor C3, capacitor C4, capacitor C9, capacitor C10, capacitor C1 connected with capacitor C3, capacitor C2 connected with capacitor C4, capacitor C1 connected with capacitor C2, MOS tube Q1, VIN power supply end; diode D5 connected with isolation drive circuit (4), resistance R9, resistance R10 connected with diode D5, resistance R10 connected with resistance R9, capacitor C13, resistance R11 and MOS tube Q1, resistance R11 connected with capacitor C13, MOS tube Q2, capacitor C12, capacitor C11, and capacitor C13, resistance R11, MOS tube Q2, capacitor C12, capacitor C11 ground, capacitor C9 connected with capacitor C12, capacitor C10 connected with capacitor C11.

3. The overvoltage protection circuit of claim 1, wherein: The power output circuit (2) includes transformer T1, capacitor CX1 connected with VIN power supply end, capacitor CX2, capacitor CX2 connected with capacitor CX1, capacitor CX3, capacitor CX4, capacitor CX4 connected with capacitor CX3, inductor L2, transformer T1 connected with inductor L2, current transformer L1 connected with transformer T1, MOS tube drive circuit (1) connected with current transformer L1, diode D1 connected with transformer T1, capacitor EC1, capacitor EC2, capacitor C6 and output terminal power supply connected with diode D1, diode D4 connected with transformer T1, capacitor EC3, capacitor EC4, output terminal power supply connected with diode D4, and capacitor EC1, capacitor EC2, capacitor EC3, capacitor EC4 also connected with transformer T1, capacitor C7 connected with capacitor C6, the transformer T1, capacitor EC1, capacitor EC2, capacitor EC3, capacitor EC4, capacitor C7 ground.

4. The overvoltage protection circuit of claim 1, wherein: The isolation drive circuit (4) includes isolation drive U2, R14 connected with PWM4A and connected with isolation drive U2, capacitor C15 connected with resistance R14, resistance R13, resistance R15 connected with PWM4B and connected with isolation drive U2, capacitor C14 connected with resistance R15, resistance R12, and capacitor C14, resistance R12, capacitor C15, resistance R13 are grounded, capacitor C18 connected with isolation drive U2, resistance R19, resistance R18, voltage detection circuit (3) connected with resistance R18, capacitor C18 connected with resistance R19, and resistance R19, capacitor C18 are grounded, capacitor C21 connected with isolation drive U2, resistance R20, resistance R20 connected with capacitor C21, and capacitor C21, resistance R20 are grounded, capacitor C19, capacitor C20, resistance R16 connected with isolation drive U2, 3.3V power end connected with resistance R16, capacitor C20 connected with capacitor C19, and capacitor C19, capacitor C20 are grounded, capacitor C16 connected with isolation drive U2, diode ZD1, diode D6, capacitor C16 connected with isolation drive U2, diode ZD1, MOS tube drive circuit (1), capacitor C17, resistance R17, diode ZD2 and diode D6 connected with isolation drive U2, capacitor C22, 12V power end connected with resistance R17, capacitor C17, diode ZD2, isolation drive U2, MOS tube drive circuit (1) connected with isolation drive U2, capacitor C17, diode ZD2, isolation drive U2, capacitor C22 are grounded.

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