Overcurrent protection circuit for electric window of automobile

Abstract

The over-current protection circuit for the electric window of the automobile comprises an operational amplifier U1, a comparator U2 and a relay RL1, the non-inverting input end of the operational amplifier U1 is connected with a load electric window motor, the inverting input end of the operational amplifier U1 is connected with the resistor R9 and the resistor R10, the output end of the operational amplifier U1 is connected to the non-inverting input end of the comparator U2, the inverting input end of the comparator U2 is connected with the resistor R2 and the resistor R3, the output end of the comparator U2 is connected with the triode Q2, the NPN type triode Q2 is connected with the PNP type triode Q1, and the PNP type triode Q1 is connected with the resistor R9. The PNP type triode Q1 is connected with the relay RL1, and the relay RL is located on a path between the electric window motor and a power supply. The utility model relates to an over-current protection circuit for an electric window of an automobile, which can provide a current overload protection circuit which is low in cost, flexible in design and free of software control so as to realize a protection function of switch control. In addition, the over-current protection function can be realized through simple discrete devices.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of circuit protection, concretely is a kind of automobile electric window overcurrent protection circuit. BACKGROUND

[0002] The development of electronic circuit is very rapid at present, and overcurrent phenomenon is usually caused by the overcurrent of some load motor in circuit or improper operation, which can burn the load motor, and overcurrent protection circuit can judge whether overcurrent phenomenon occurs in circuit by detecting the size of load current, and rapidly cut off the circuit when overcurrent occurs, and the damage of load motor can be caused if corresponding protection measures are not taken. SUMMARY

[0003] The utility model discloses an automobile electric window overcurrent protection circuit to solve the problems in the above background.

[0004] To solve the above technical problems, the utility model provides the following technical scheme: including operational amplifier U1, comparator U2 and relay RL1;

[0005] Operational amplifier U1 same-phase input end is connected with load electric window motor, and opposite-phase input end is connected resistance R9 and resistance R10, and operational amplifier U1 output end is connected to the same-phase input end of comparator U2, and opposite-phase input end of comparator U2 is connected resistance R2 and resistance R3, and the output end of comparator U2 is connected triode Q2, and NPN type triode Q2 is connected PNP type triode Q1, and PNP type triode Q1 is connected with relay RL1, and relay RL is located in the passageway between electric window motor and power supply.

[0006] Preferably, the electric window motor is connected in series with a resistor R8, and one end of the resistor R8 is connected to the ground.

[0007] Preferably, the same-phase input end of the operational amplifier U1 is further connected with a resistor R6.

[0008] Preferably, the output end of the comparator U2 is further connected with a pull-up resistor R5.

[0009] Preferably, the base of the NPN type triode Q2 is connected with the collector of the PNP type triode Q1 through a resistor R4.

[0010] Compared with the prior art, the utility model has the beneficial effects that:

[0011] The utility model provides a kind of automobile electric window overcurrent protection circuit, can provide a kind of current overload protection circuit with low cost, design flexible and without software control, to further realize the protection function of switch control.And, the present application can realize overcurrent protection function by simple discrete device. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 It is the whole circuit structure schematic diagram of the utility model system. DETAILED DESCRIPTION

[0013] The technical scheme in the embodiments of the utility model will be clearly and completely described below with reference to the drawings in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the utility model.

[0014] Please refer to Figure 1 As shown in the figure, see Figure 1 , through triode Q1, Q2, resistance R1, R2, R3, R4, R5, R6, R7, R8, R9, R10, operational amplifier U1, comparator U2, relay RL1, diode D1, overcurrent protection function is realized.

[0015] Resistance R8 and load motor window are in series, and the current is equal, which is a sampling resistance; resistance R6 is the input end current limiting resistance of amplifier U1; by adjusting the resistance value of R9 and R10, the amplifier U1 can be set to an appropriate amplification factor; the function of amplifier U1 is to amplify the voltage collected at the load end; by adjusting the resistance value of R2 and R3, the comparison voltage of comparator U2 can be set; resistance R5 is a pull-up resistor; resistance R7 is the current limiting resistance of the base of triode Q2; diode D1 is a freewheeling diode of the relay coil. When the current of the load motor window is too large, the comparator U2 outputs a high level, and the triode Q2 is turned on. After Q2 is turned on, the PNP triode Q1 is provided with a conduction condition, and after Q1 is turned on, the current flows through the coil of relay RL1, and the relay is attracted. At this time, the power supply of the motor window is cut off. Since the current flows through Q1 and resistance R4 to the base of Q2 to form a self-locking, even if the comparator outputs a low level, the relay still remains attracted, and the motor window has no power supply. The utility model is mainly used for detecting the load current of the motor window of the automobile to cut off the power supply, so as to achieve the function of protecting the load.

[0016] Although the embodiments of the utility model have been shown and described, it can be understood by those skilled in the art that various changes, modifications, replacements and variations can be made to these embodiments without departing from the principles and spirits of the utility model, and the scope of the utility model is defined by the appended claims and their equivalents.

Claims

1. An overcurrent protection circuit for automotive power windows, characterized in that: It comprises an operational amplifier U1, a comparator U2 and a relay RL1. The in-phase input end of the operational amplifier U1 is connected with a load electric window motor, the anti-phase input end is connected with a resistor R9 and a resistor R10, the output end of the operational amplifier U1 is connected with the in-phase input end of the comparator U2, the anti-phase input end of the comparator U2 is connected with a resistor R2 and a resistor R3, the output end of the comparator U2 is connected with a triode Q2, the NPN triode Q2 is connected with a PNP triode Q1, the PNP triode Q1 is connected with the relay RL1, and the relay RL is located on the path between the electric window motor and the power supply.

2. An overcurrent protection circuit for an automotive power window according to claim 1, characterized in that: The electric window motor is connected in series with a resistor R8, and one end of the resistor R8 is grounded.

3. An automotive power window overcurrent protection circuit according to claim 2, wherein: The in-phase input end of the operational amplifier U1 is also connected with a resistor R6.

4. The overcurrent protection circuit for an automotive power window according to claim 1, characterized by: The output end of the comparator U2 is also connected with a pull-up resistor R5.

5. The overcurrent protection circuit for an automotive power window according to claim 1, characterized by: The resistor R4 is connected between the base of the NPN triode Q2 and the collector of the PNP triode Q1.

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