CN209767144U - A New Type of Motor Drive Overcurrent Protection Circuit - Google Patents

Abstract

The utility model relates to a novel motor drive overcurrent protection circuit. Including current sampling circuit, amplifier circuit, voltage comparison circuit, optocoupler self-locking circuit, over-current reset circuit, start-up delay circuit and shutdown circuit. The circuit of the utility model has the functions of self-locking and isolation, which ensures that the circuit can maintain a closed state after overcurrent, has a reset function, and can realize the overcurrent protection of the motor with a self-locking function.

Description

A New Type of Motor Drive Overcurrent Protection Circuit

technical field

The utility model relates to a novel motor drive overcurrent protection circuit.

Background technique

In the process of motor control, it is necessary to detect the motor drive current in real time and adopt over-current protection. For the motor drive over-current protection isolated from control and drive, two methods are generally used: over-current fuse protection completed by placing a fuse at the mains input terminal, However, due to its relatively slow fusing speed and low accuracy of fusing current, it still cannot guarantee that some devices will not be damaged and burned; software overcurrent protection means that the current sampling software judges whether the current exceeds the maximum threshold, and the software turns off the motor drive signal. There is a time lag between the controller executing the judgment and closing the signal, and the controller has the problem that the CPU crashes and the software judgment is invalid. Therefore, in addition to the above two methods, the overcurrent protection of the motor drive isolated from the control and drive needs to design hardware overcurrent protection, and the overcurrent protection hardware circuit is required to have the function of self-locking and isolation to ensure that the circuit can be maintained after the overcurrent occurs. In the closed state, after the controller program judges that the motor drive is normal, the software is reset through the controller CPU.

Contents of the invention

The purpose of this utility model is to provide a new type of motor drive overcurrent protection circuit, which has the functions of self-locking and isolation to ensure that the circuit can remain closed after overcurrent, and has a reset function, which can realize the self-locking function of the motor overcurrent protection.

In order to achieve the above purpose, the technical solution of the utility model is: a new type of motor drive overcurrent protection circuit, including a current sampling circuit, an amplification circuit, a voltage comparison circuit, an optocoupler self-locking circuit, an overcurrent reset circuit, a start-up delay Time circuit and shutdown circuit;

The current sampling circuit includes a cement resistor, a first resistor, and a first capacitor, one end of the cement resistor, a bus bar, and one end of the first resistor, and the other end of the first resistor is connected to the ground through the first capacitor and the other end of the cement resistor;

The amplifying circuit includes a second resistor, a third resistor, and a first operational amplifier, one end of the second resistor is connected to ground, the other end of the second resistor is connected to one end of the third resistor, and the other end of the third resistor is connected to the first The output terminal of the operational amplifier is connected, the inverting terminal of the first operational amplifier is connected with the connection point of the first resistor and the first capacitor, and the non-inverting terminal of the first operational amplifier is connected with the connection point of the second resistor and the third resistor;

The voltage comparison circuit includes a second operational amplifier, a fourth resistor, a fifth resistor, and a seventh resistor. The non-inverting terminal of the second operational amplifier is connected to the output terminal of the first operational amplifier, and the inverting terminal of the second operational amplifier is connected to the output terminal of the second operational amplifier through the first operational amplifier. The four resistors are connected to the +15V power supply, the inverting terminal of the second operational amplifier is also connected to the ground through the fifth resistor, and the output terminal of the first operational amplifier is connected to the self-locking circuit of the optocoupler through the seventh resistor;

The optocoupler self-locking circuit includes a first optocoupler, a third tube coupler, a first triode, an eighth resistor, and a light emitting diode, the base of the first triode is connected to the seventh resistor, and the first triode is connected to the seventh resistor. The collector of the triode is connected to the +15V power supply through the eighth resistor, the collector of the first triode is also connected to the collector of the receiving end of the first optocoupler, and the emitter of the first triode is connected to the first optocoupler. The emitter anode of the coupler is connected to the receiver emitter of the first optocoupler, the emitter cathode of the first optocoupler is connected to the emitter anode of the third optocoupler, and the emitter cathode of the third optocoupler passes through The light-emitting diode is connected to the ground, the collector of the receiving end and the emitter of the receiving end of the third optocoupler are connected to the start-up delay circuit, and the anode and cathode of the emitting end of the first optocoupler are connected to the overcurrent reset circuit connection;

The overcurrent reset circuit includes a second optocoupler and a sixth resistor, the anode of the emitter of the second optocoupler is connected to the +5V power supply through the sixth resistor, and the cathode of the emitter of the second optocoupler is used as an overcurrent reset Pins, the receiver collector and the receiver emitter of the second optocoupler are respectively connected to the emitter anode and emitter cathode of the first optocoupler;

The start-up delay circuit includes a ninth resistor and a second capacitor, one end of the ninth resistor is connected to a +5V power supply, and the other end of the ninth resistor and one end of the second capacitor are connected to the receiving end set of the third optocoupler An electrode, the other end of the second capacitor is connected to the receiving end emitter of the third optocoupler;

The shut-off circuit includes a tenth resistor and a second transistor, the base of the second transistor is connected to one end of the second capacitor, and the emitter of the second transistor is connected to the other end of the second capacitor. Connect to the ground, the collector of the second triode is connected to the +5V power supply through the tenth resistor, and the collector of the second triode is also used as a PWM shutdown pin.

In an embodiment of the present invention, both the first diode and the second diode are NPN transistors.

In an embodiment of the present invention, the ground between the emitter of the second triode and the other end of the second capacitor is a digital ground.

Compared with the prior art, the utility model has the following beneficial effects: the circuit of the utility model has the functions of self-locking and isolation, which ensures that the circuit can remain closed after overcurrent, and has a reset function, which can realize the self-locking function of the motor. overcurrent protection.

Description of drawings

Fig. 1 is a functional block diagram of the utility model circuit.

Fig. 2 is a circuit diagram of the utility model.

Detailed ways

Below in conjunction with accompanying drawing, the technical solution of the utility model is described in detail.

As shown in Figure 1, the utility model provides a novel motor-driven overcurrent protection circuit with self-locking function based on an optocoupler, including a current sampling circuit, an amplifier circuit, a voltage comparison circuit, and an optocoupler self-locking circuit. circuit, overcurrent reset circuit, start-up delay circuit and shutdown circuit.

As shown in Figure 2, the current sampling circuit includes a resistor R1, a cement resistor Rs, and a capacitor C1; the cement resistor is connected to the bus bar and the resistor R1 respectively, one end of the capacitor C1 is grounded, and the other end is connected to the resistor R1, and the resistor R1 and the capacitor C1 form a Low pass RC filtering.

The amplifying circuit includes an operational amplifier U4A, resistors R2 and R3; the resistor R2 is connected to the same-phase terminal of the operational amplifier U4A and one end of R3, and the other end of R2 is connected to the ground wire PGND of the motor drive power part; the other end of R3 is connected to the output terminal of the operational amplifier U4A ; The inverting terminal of the operational amplifier U4A is connected to the resistor R1 and the capacitor C1.

The voltage comparison circuit includes an operational amplifier U4B, resistors R4, R5 and R7; one end of the resistor R4 is connected to the inverting terminal of the resistor R5 and the operational amplifier U4B, the other end of the resistor R4 is connected to the +15V power supply, and the other end of the R5 is connected to the PGND; One end of R7 is connected to the output end of U4B, and the other end is connected to the base of NPN transistor Q1; pin 8 and pin 4 of operational amplifier U4 are respectively connected to +15V and PGND.

The optocoupler self-locking circuit includes optocouplers U1 and U3, NPN transistor Q1, resistor R8 and light emitting diode LED. The collector of NPN transistor Q1 is connected to one end of resistor R8 and the fourth pin of optocoupler U1; the other end of resistor R8 is connected to +15V; the emitter of NPN transistor Q1 is connected to the first pin of optocoupler U1 and the first pin of U2 4 pins are connected; the second pin of optocoupler U1 is connected to the third pin of U2 and the first pin of U1; the second pin of optocoupler U3 is connected to the anode of LED, the third pin is connected to capacitor C2 and the controller The digital ground line DGND is connected, the fourth pin is connected with the other end of the capacitor C2, and one end of the resistor R9.

The overcurrent reset circuit includes an optocoupler U2 and a resistor R6; wherein, the first pin of the optocoupler U2 is connected to one end of the resistor R6, and the second pin is connected to the microprocessor for realizing software reset; the other end of the resistor R6 Connected to +5V; the 3rd pin of optocoupler U2 is connected to the 2nd pin of U1 and the 1st pin of U3; the 4th pin of U2 is connected to the emitter of NPN transistor Q1, and the 1st and 3rd pins of optocoupler U1 connected.

The start-up delay circuit includes a resistor R9 and a capacitor C2; wherein, one end of the resistor R9 is connected to the capacitor C2, the 4th pin of the optocoupler U3, and the base of the NPN transistor Q2; the other end of the resistor R9 is connected to +5V; the capacitor C2 The other end is connected with the third pin of optocoupler U3 and DGND.

The shutdown circuit includes a resistor R10 and an NPN transistor Q2. The base of the NPN transistor Q2 is connected to the capacitor C2 and the resistor R9; the collector is connected to one end of the resistor R10 and PWM wave off, and the emitter is connected to DGND; the other end of the resistor R10 is connected to +5V.

The above are the preferred embodiments of the utility model, and all changes made according to the technical solution of the utility model, when the functional effect produced does not exceed the scope of the technical solution of the utility model, all belong to the protection scope of the utility model.

Claims (3)

1. a novel motor drive overcurrent protection circuit is characterized by comprising a current sampling circuit, an amplifying circuit, a voltage comparison circuit, an optical coupler self-locking circuit, an overcurrent reset circuit, a start delay circuit and a turn-off circuit;

The current sampling circuit comprises a cement resistor, a first resistor and a first capacitor, wherein one end of the cement resistor is connected with one end of the bus and one end of the first resistor, and the other end of the first resistor is connected to the ground through the first capacitor and the other end of the cement resistor;

The amplifying circuit comprises a second resistor, a third resistor and a first operational amplifier, wherein one end of the second resistor is connected to the ground, the other end of the second resistor is connected with one end of the third resistor, the other end of the third resistor is connected with the output end of the first operational amplifier, the inverting end of the first operational amplifier is connected with the connection point of the first resistor and the first capacitor, and the in-phase end of the first operational amplifier is connected with the connection point of the second resistor and the third resistor;

The voltage comparison circuit comprises a second operational amplifier, a fourth resistor, a fifth resistor and a seventh resistor, wherein the in-phase end of the second operational amplifier is connected with the output end of the first operational amplifier, the inverting end of the second operational amplifier is connected to a +15V power supply through the fourth resistor, the inverting end of the second operational amplifier is also connected to the ground through the fifth resistor, and the output end of the first operational amplifier is connected with the self-locking circuit of the optical coupler through the seventh resistor;

The self-locking circuit of the optical coupler comprises a first optical coupler, a third tube coupler, a first triode, an eighth resistor and a light-emitting diode, wherein the base electrode of the first triode is connected with a seventh resistor, the collector electrode of the first triode is connected to a +15V power supply through the eighth resistor, the collector electrode of the first triode is also connected with the collector electrode of the receiving end of the first optical coupler, the emitter electrode of the first triode is connected with the anode of the transmitting end of the first optical coupler and the emitter electrode of the receiving end of the first optical coupler, the cathode of the transmitting end of the first optical coupler is connected with the anode of the transmitting end of the third optical coupler, the cathode of the transmitting end of the third optical coupler is connected to the ground through the light-emitting diode, the collector electrode of the receiving end of the third optical coupler and the emitter electrode of the receiving, the emitting end anode and the emitting end cathode of the first optical coupler are connected with the overcurrent reset circuit;

the overcurrent reset circuit comprises a second optical coupler and a sixth resistor, wherein the anode of the transmitting end of the second optical coupler is connected to a +5V power supply through the sixth resistor, the cathode of the transmitting end of the second optical coupler is used as an overcurrent reset pin, and the collector and the emitter of the receiving end of the second optical coupler are respectively connected with the anode and the cathode of the transmitting end of the first optical coupler;

The starting time delay circuit comprises a ninth resistor and a second capacitor, one end of the ninth resistor is connected to a +5V power supply, the other end of the ninth resistor and one end of the second capacitor are connected to a receiving end collector of the third optical coupler, and the other end of the second capacitor is connected to a receiving end emitter of the third optical coupler;

The turn-off circuit comprises a tenth resistor and a second triode, wherein the base electrode of the second triode is connected with one end of a second capacitor, the emitting electrode of the second triode and the other end of the second capacitor are connected to the ground, the collecting electrode of the second triode is connected to a +5V power supply through the tenth resistor, and the collecting electrode of the second triode is also used as a PWM turn-off pin.

2. The novel motor-driven over-current protection circuit as claimed in claim 1, wherein the first and second transistors are NPN transistors.

3. The novel motor-driven overcurrent protection circuit according to claim 1, wherein the grounding of the emitter of the second triode and the other end of the second capacitor is a digital ground.