阅读说明：本技术 一种过流保护电路 (Overcurrent protection circuit ) 是由 王庆 陈友坚 于 2019-11-29 设计创作，主要内容包括：本发明涉及一种过流保护电路,包括：桥式整流电路、电机负载接口电路、MOS管输出及电流采样电路、采样高压隔离电路、MOS管驱动和保护电路、过流保护比较电路、MCU控制电路、过流保护基准电路、光耦隔离电路I、光耦隔离电路II、光耦隔离电路III。本发明可实现功率驱动的过流保护,结合了硬件电路和软件控制的各自优点,既有硬件电路的快速响应和动作可靠,又有软件控制的灵活,参数可调；MCU控制电路和MOS管驱动和保护电路之间的PWM信号和过流保护信号都采用光耦隔离,没有电气干扰,保证MCU电路的稳定工作。(The invention relates to an overcurrent protection circuit, comprising: the device comprises a bridge rectifier circuit, a motor load interface circuit, an MOS (metal oxide semiconductor) tube output and current sampling circuit, a sampling high-voltage isolation circuit, an MOS tube driving and protecting circuit, an overcurrent protection comparison circuit, an MCU (microprogrammed control unit) control circuit, an overcurrent protection reference circuit, an optical coupling isolation circuit I, an optical coupling isolation circuit II and an optical coupling isolation circuit III. The invention can realize overcurrent protection of power drive, combines the advantages of a hardware circuit and software control, has the advantages of quick response and reliable action of the hardware circuit, flexible software control and adjustable parameters; PWM signals and overcurrent protection signals between the MCU control circuit and the MOS tube driving and protecting circuit are isolated by optical couplers, no electric interference exists, and stable work of the MCU circuit is guaranteed.)

1. An overcurrent protection circuit, comprising: the device comprises a bridge rectifier circuit, a motor load interface circuit, an MOS (metal oxide semiconductor) tube output and current sampling circuit, a sampling high-voltage isolation circuit, an MOS tube driving and protecting circuit, an overcurrent protection comparison circuit, an MCU (microprogrammed control unit) control circuit, an overcurrent protection reference circuit, an optical coupling isolation circuit I, an optical coupling isolation circuit II and an optical coupling isolation circuit III; the bridge rectifier circuit is connected with alternating current and is input into the motor load interface circuit after being rectified by the bridge rectifier circuit; the motor load interface circuit is respectively connected with the sampling high-voltage isolation circuit and the MOS tube output and current sampling circuit; the MOS tube driving and protecting circuit is respectively connected with the sampling high-voltage isolating circuit, the MOS tube output and current sampling circuit, the overcurrent protection comparison circuit and the optical coupling isolating circuit I; the overcurrent protection comparison circuit, the optical coupling isolation circuit III and the MCU control circuit are sequentially connected; the MCU control circuit, the optical coupling isolation circuit II, the overcurrent protection reference circuit and the overcurrent protection comparison circuit are sequentially connected; the MCU control circuit is connected with the MOS tube driving and protecting circuit through the optical coupling isolating circuit I.

2. An overcurrent protection circuit according to claim 1, wherein: the bridge rectifier circuit comprises a fuse F1, a piezoresistor ZR1, an EMC capacitor C1 and a rectifier bridge stack D1; one end of the piezoresistor ZR1, one end of the EMC capacitor C1 and one end of the rectifier bridge stack D1 are respectively connected with an AC live wire interface through a protective tube F1, and the other end of the piezoresistor ZR1, the other end of the EMC capacitor C1 and the other end of the rectifier bridge stack D1 are respectively connected with an AC zero wire interface; the piezoresistor ZR1, the EMC capacitor C1 and the rectifier bridge stack D1 are connected in parallel; the fuse F1 plays a role in short-circuit protection, and the piezoresistor ZR1 and the EMC capacitor C14 are used for enhancing the electromagnetic compatibility of the circuit; the bridge rectifier D1 is used to convert ac power to dc power.

3. An overcurrent protection circuit according to claim 1, wherein: the motor load interface circuit comprises a relay J1, a relay J2, an RS1M diode D2, an S14L diode D3 and an S14L diode D4; the relay J1 and the relay J2 control the positive and negative rotation and stop of the motor; diodes D2 and D3 of RS1M and S14L and D4 of S14L are freewheeling diodes, diode D2 of RS1M continues current for the externally connected direct current motor, diode D3 of S14L and diode D4 of S14L respectively continue current for the relay J1 and the relay J2, and a reverse current path is provided when the inductive load is turned off.

4. An overcurrent protection circuit according to claim 1, wherein: the MOS tube output and current sampling circuit comprises an MOS tube Q6, a voltage regulator tube D7, a capacitor C4, a resistor R19 and a resistor R90; the drain electrode of the MOS tube Q6 is connected with the capacitor C4 and the output end OUT, the grid electrode of the MOS tube Q6 is connected with the voltage-regulator tube D7 and the resistor R19, and the source electrode of the MOS tube Q6 is connected with the resistor R90; the voltage regulator tube D7 is used for clamping the grid voltage of the MOS tube Q6 and ensuring that the driving voltage is not higher than 18V; the capacitor C4 is a switch buffer capacitor of the drain electrode of the MOS transistor Q6; the resistor R90 is a main sampling resistor, the MOS tube Q6 is an auxiliary sampling circuit, and a sampling signal is output from an OUT end.

5. An overcurrent protection circuit according to claim 1, wherein: the sampling high-voltage isolation circuit comprises a diode D6 and a resistor R10; the diode D6 and the resistor R10 are connected to each other.

6. An overcurrent protection circuit according to claim 1, wherein: the MOS tube driving and protecting circuit comprises a C8050 triode Q8, a C8050 triode Q9, a C8050 triode Q10, a C8050 triode Q11, a C8050 triode Q3, a C8550 triode Q12, a resistor R9, a resistor R37, a resistor R83, a resistor R11 and a resistor R14; the resistor R17 is connected with the base electrode of the C8050 triode Q8, and the collector electrode of the C8050 triode Q8 is respectively connected with the resistor R9, the resistor R37 and the resistor R83; the resistor R37 is also connected with the base of a C8050 triode Q9, the collector of the C8050 triode Q9 is respectively connected with a resistor R10, a resistor R24 and a diode D6, wherein the resistor R24 is connected to the positive input end of the over-current protection comparison circuit, and the diode D6 is connected to the collector of the MOS tube Q6; the resistor R83 is also connected with the base electrode of a C8050 triode Q10, and the collector electrode of the C8050 triode Q10 is respectively connected with a resistor R11, a C8050 triode Q11, a C8050 triode Q3 and a C8050 triode Q12; the base electrode of the C8050 triode Q11 is connected with an output end resistor R25 of the overcurrent protection comparison circuit; the C8050 triode Q3 and the C8050 triode Q12 form a push-pull circuit, and the push-pull circuit is output to the grid electrode of the MOS transistor Q6 through a resistor R14.

7. An overcurrent protection circuit according to claim 1, wherein: the over-current protection comparison circuit comprises a comparator IC4A, a resistor R24, a resistor R25 and a capacitor C7; the negative input end of the comparator IC4A is connected with a capacitor C6 of the overcurrent protection reference circuit, the positive input end of the IC4A is respectively connected with a capacitor C7 and a resistor R24, and the output end of the IC4A is connected with a resistor R25.

8. An overcurrent protection circuit according to claim 1, wherein: the MCU control circuit comprises an MCU chip IC6, a crystal oscillator Y1, a capacitor C9, a capacitor C17, a capacitor C18, a capacitor C39, a capacitor C40, a capacitor C37, a capacitor C38, a capacitor C21 and a resistor R36; a capacitor C9, a capacitor C18, a capacitor C39 and a capacitor C40 are filter capacitors of a power supply pin of the MCU chip IC6, and a capacitor C17 is a filter capacitor of reference voltage inside the MCU chip IC 6; the crystal oscillator Y1 is a quartz crystal oscillator; the capacitor C37 and the capacitor C38 are load capacitors of the oscillator and are used for providing stable clock frequency for the MCU chip IC 6; the resistor R36 and the capacitor C21 are reset circuits of the MCU chip IC 6; the MCU control circuit is used for generating a driving signal M-PWM and an overcurrent protection reference signal C-PWM and reading an overcurrent protection state signal.

9. An overcurrent protection circuit according to claim 1, wherein: the optical coupling isolation circuit I comprises an optical coupling IC2, a resistor R16, a resistor R20 and a resistor R17, and is used for isolation transmission of M-PWM signals;

the optical coupling isolation circuit II comprises an optical coupling IC8, a resistor R28 and a resistor R31, and is used for isolating and transmitting a C-PWM signal;

the optical coupling isolation circuit III comprises an optical coupling IC5, a resistor R29, a resistor R26 and a capacitor C42; and the optical coupling isolation circuit III is used for transmitting overcurrent protection state signals.

10. An overcurrent protection circuit according to claim 1, wherein: the over-current protection reference circuit comprises a triode Q14, a triode Q15, a resistor R27, a resistor R32, a resistor R30, a capacitor C5 and a capacitor C6; the C-PWM signal input by the optical coupling isolation circuit II is subjected to push-pull driving of a triode Q14 and a triode Q15, then is divided by a resistor R27 and a resistor R32 to become a PWM signal, and then is input into a low-pass filter circuit consisting of a capacitor C5, a resistor R30 and a capacitor C6 to be processed to become smooth direct-current voltage; the voltage is a reference voltage of overcurrent protection and is used for comparing with an effective overcurrent protection signal, and the comparison result determines whether the circuit enters an overcurrent protection state or not.

Technical Field

The invention relates to the technical field of protection circuits, in particular to an overcurrent protection circuit.

Background

In the aspect of power electronic technology, a novel semiconductor power device is widely applied due to high power, high speed, small volume and simple control. However, semiconductor devices have inherent disadvantages, namely, poor overload capability, insufficient shock resistance, and susceptibility to damage by slight overvoltage or overcurrent. The overcurrent protection is the key point, and the technical difficulty is also large. The general overcurrent protection circuit has a hardware circuit and also has a circuit of hardware and software. The hardware protection circuit has the advantages of good real-time performance and high response speed, but has simple function and is generally current-limiting protection. The hardware plus software protection circuit has better protection function due to the participation of software control, but has slightly poor real-time performance and inferior overall reliability to the hardware circuit. Therefore, it is very necessary to design an overcurrent protection circuit.

Disclosure of Invention

The invention aims to overcome the defects and provides the overcurrent protection circuit, which can realize power-driven overcurrent protection, combines the advantages of a hardware circuit and software control, has the advantages of quick response and reliable action of the hardware circuit, flexible software control and adjustable parameters; PWM signals and overcurrent protection signals between the MCU control circuit and the MOS tube driving and protecting circuit are isolated by optical couplers, no electric interference exists, and stable work of the MCU circuit is guaranteed.

The invention achieves the aim through the following technical scheme: an overcurrent protection circuit comprising: the device comprises a bridge rectifier circuit, a motor load interface circuit, an MOS (metal oxide semiconductor) tube output and current sampling circuit, a sampling high-voltage isolation circuit, an MOS tube driving and protecting circuit, an overcurrent protection comparison circuit, an MCU (microprogrammed control unit) control circuit, an overcurrent protection reference circuit, an optical coupling isolation circuit I, an optical coupling isolation circuit II and an optical coupling isolation circuit III; the bridge rectifier circuit is connected with alternating current and is input into the motor load interface circuit after being rectified by the bridge rectifier circuit; the motor load interface circuit is respectively connected with the sampling high-voltage isolation circuit and the MOS tube output and current sampling circuit; the MOS tube driving and protecting circuit is respectively connected with the sampling high-voltage isolating circuit, the MOS tube output and current sampling circuit, the overcurrent protection comparison circuit and the optical coupling isolating circuit I; the overcurrent protection comparison circuit, the optical coupling isolation circuit III and the MCU control circuit are sequentially connected; the MCU control circuit, the optical coupling isolation circuit II, the overcurrent protection reference circuit and the overcurrent protection comparison circuit are sequentially connected; the MCU control circuit is connected with the MOS tube driving and protecting circuit through the optical coupling isolating circuit I.

Preferably, the bridge rectifier circuit comprises a fuse F1, a piezoresistor ZR1, an EMC capacitor C1 and a rectifier bridge stack D1; one end of the piezoresistor ZR1, one end of the EMC capacitor C1 and one end of the rectifier bridge stack D1 are respectively connected with an AC live wire interface through a protective tube F1, and the other end of the piezoresistor ZR1, the other end of the EMC capacitor C1 and the other end of the rectifier bridge stack D1 are respectively connected with an AC zero wire interface; the piezoresistor ZR1, the EMC capacitor C1 and the rectifier bridge stack D1 are connected in parallel; the fuse F1 plays a role in short-circuit protection, and the piezoresistor ZR1 and the EMC capacitor C14 are used for enhancing the electromagnetic compatibility of the circuit; the bridge rectifier D1 is used to convert ac power to dc power.

Preferably, the motor load interface circuit comprises a relay J1, a relay J2, an RS1M diode D2, an S14L diode D3, and an S14L diode D4; the relay J1 and the relay J2 control the positive and negative rotation and stop of the motor; diodes D2 and D3 of RS1M and S14L and D4 of S14L are freewheeling diodes, diode D2 of RS1M continues current for the externally connected direct current motor, diode D3 of S14L and diode D4 of S14L respectively continue current for the relay J1 and the relay J2, and a reverse current path is provided when the inductive load is turned off.

Preferably, the MOS transistor output and current sampling circuit comprises a MOS transistor Q6, a voltage regulator D7, a capacitor C4, a resistor R19, and a resistor R90; the drain electrode of the MOS tube Q6 is connected with the capacitor C4 and the output end OUT, the grid electrode of the MOS tube Q6 is connected with the voltage-regulator tube D7 and the resistor R19, and the source electrode of the MOS tube Q6 is connected with the resistor R90; the voltage regulator tube D7 is used for clamping the grid voltage of the MOS tube Q6 and ensuring that the driving voltage is not higher than 18V; the capacitor C4 is a switch buffer capacitor of the drain electrode of the MOS transistor Q6; the resistor R90 is a main sampling resistor, the MOS tube Q6 is an auxiliary sampling circuit, and a sampling signal is output from an OUT end.

Preferably, the sampling high-voltage isolation circuit comprises a diode D6 and a resistor R10; the diode D6 and the resistor R10 are connected to each other.

Preferably, the MOS transistor driving and protecting circuit comprises a C8050 triode Q8, a C8050 triode Q9, a C8050 triode Q10, a C8050 triode Q11, a C8050 triode Q3, a C8550 triode Q12, a resistor R9, a resistor R37, a resistor R83, a resistor R11 and a resistor R14; the resistor R17 is connected with the base electrode of the C8050 triode Q8, and the collector electrode of the C8050 triode Q8 is respectively connected with the resistor R9, the resistor R37 and the resistor R83; the resistor R37 is also connected with the base of a C8050 triode Q9, the collector of the C8050 triode Q9 is respectively connected with a resistor R10, a resistor R24 and a diode D6, wherein the resistor R24 is connected to the positive input end of the over-current protection comparison circuit, and the diode D6 is connected to the collector of the MOS tube Q6; the resistor R83 is also connected with the base electrode of a C8050 triode Q10, and the collector electrode of the C8050 triode Q10 is respectively connected with a resistor R11, a C8050 triode Q11, a C8050 triode Q3 and a C8050 triode Q12; the base electrode of the C8050 triode Q11 is connected with an output end resistor R25 of the overcurrent protection comparison circuit; the C8050 triode Q3 and the C8050 triode Q12 form a push-pull circuit, and the push-pull circuit is output to the grid electrode of the MOS transistor Q6 through a resistor R14.

Preferably, the overcurrent protection comparison circuit comprises a comparator IC4A, a resistor R24, a resistor R25 and a capacitor C7; the negative input end of the comparator IC4A is connected with a capacitor C6 of the overcurrent protection reference circuit, the positive input end of the IC4A is respectively connected with a capacitor C7 and a resistor R24, and the output end of the IC4A is connected with a resistor R25.

Preferably, the MCU control circuit includes an MCU chip IC6, a crystal oscillator Y1, a capacitor C9, a capacitor C17, a capacitor C18, a capacitor C39, a capacitor C40, a capacitor C37, a capacitor C38, a capacitor C21, and a resistor R36; a capacitor C9, a capacitor C18, a capacitor C39 and a capacitor C40 are filter capacitors of a power supply pin of the MCU chip IC6, and a capacitor C17 is a filter capacitor of reference voltage inside the MCU chip IC 6; the crystal oscillator Y1 is a quartz crystal oscillator; the capacitor C37 and the capacitor C38 are load capacitors of the oscillator and are used for providing stable clock frequency for the MCU chip IC 6; the resistor R36 and the capacitor C21 are reset circuits of the MCU chip IC 6. The MCU control circuit is used for generating a driving signal M-PWM and an overcurrent protection reference signal C-PWM and reading an overcurrent protection state signal.

Preferably, the optical coupling isolation circuit I comprises an optical coupling IC2, a resistor R16, a resistor R20 and a resistor R17, and the optical coupling isolation circuit I is used for isolating and transmitting M-PWM signals; the optical coupling isolation circuit II comprises an optical coupling IC8, a resistor R28 and a resistor R31, and is used for isolating and transmitting a C-PWM signal; the optical coupling isolation circuit III comprises an optical coupling IC5, a resistor R29, a resistor R26 and a capacitor C42; and the optical coupling isolation circuit III is used for transmitting overcurrent protection state signals.

Preferably, the overcurrent protection reference circuit comprises a transistor Q14, a transistor Q15, a resistor R27, a resistor R32, a resistor R30, a capacitor C5 and a capacitor C6; the C-PWM signal input by the optical coupling isolation circuit II is subjected to push-pull driving of a triode Q14 and a triode Q15, then is divided by a resistor R27 and a resistor R32 to become a PWM signal, and then is input into a low-pass filter circuit consisting of a capacitor C5, a resistor R30 and a capacitor C6 to be processed to become smooth direct-current voltage; the voltage is a reference voltage of overcurrent protection and is used for comparing with an effective overcurrent protection signal, and the comparison result determines whether the circuit enters an overcurrent protection state or not.

The invention has the beneficial effects that: the invention can realize overcurrent protection of power drive, combines the advantages of a hardware circuit and software control, has the advantages of quick response and reliable action of the hardware circuit, flexible software control and adjustable parameters; PWM signals and overcurrent protection signals between the MCU control circuit and the MOS tube driving and protecting circuit are isolated by optical couplers, no electric interference exists, and stable work of the MCU circuit is guaranteed.

Drawings

FIG. 1 is a schematic structural view of the present invention;

fig. 2 is a circuit schematic of the present invention.

Detailed Description

The invention will be further described with reference to specific examples, but the scope of the invention is not limited thereto: