Current protection circuit of direct current motor

Abstract

The utility model discloses a current protection circuit of a direct current motor, which comprises a direct current motor positive and negative rotation driving power supply and a current isolation sampling unit which are connected with the motor, and a bridge rectifier unit, a power supply voltage stabilizing unit and a signal processing unit which are sequentially connected with the direct current motor positive and negative rotation driving power supply, and a signal amplification unit and a switch control circuit are respectively connected between the signal processing unit and the current isolation sampling unit and between the signal processing unit and the motor. According to the utility model, the motor stroke of the linear push rod can be controlled, the motor can be protected, the device is safe and reliable, the whole circuit structure is simple, the cost is low, and the device has practical popularization significance.

Description

Technical Field

[0001] The utility model relates to the technical field of circuit control, in particular to a DC motor current protection circuit. Background Art

[0002] With the gradual popularization of electric lift tables and electric sofas in life, the linear actuator of the motor (also called linear actuator) is more and more widely used in lift tables and electric sofas, and the product has also been supported and recognized by users.

[0003] The stroke control principle of this linear push rod is to use a stroke limit switch to achieve stroke control. A stroke switch is provided at each end of the push rod stroke. When the push rod runs to the stroke end, it will hit the stroke switch, cutting off the control circuit and thus controlling the running stroke of the linear push rod. This stroke switch is usually installed on a small PCB board to form a stroke plate. The two stroke plates at both ends of the linear push rod need to be connected by wires, and a forward and reverse control diode is installed on the stroke plate. The production of this stroke plate requires manual welding, which is time-consuming and labor-intensive, with cumbersome procedures and high overall costs. In addition, when the push rod runs to the two stroke ends, if the load is large at this time, the circuit will be cut off after hitting the stroke switch. The load will cause the stroke to slide, resulting in a hiccup-like working mode of the system, affecting the customer's experience of the product. Utility Model Content

[0004] The purpose of the utility model is to propose a DC motor current protection circuit to address the deficiencies of the prior art, to replace the existing stroke plate, to control the motor stroke of the linear push rod while protecting the motor, which is safe and reliable, has a simple overall circuit structure, is low in cost, and has practical promotion significance.

[0005] The technical solution to achieve the purpose of this utility model is:

[0006] A DC motor current protection circuit comprises a DC motor forward and reverse drive power supply and a current isolation sampling unit both connected to the motor, and a bridge rectifier unit, a power supply stabilizing unit and a signal processing unit connected to the DC motor forward and reverse drive power supply in sequence, wherein a signal amplification unit and a switch control circuit are respectively connected between the signal processing unit, the current isolation sampling unit and the motor.

[0007] Furthermore, the bridge rectifier unit adopts a full-bridge rectifier structure composed of four rectifier diodes.

[0008] Furthermore, the bridge rectifier unit includes a rectifier diode D1, a rectifier diode D2, a rectifier diode D3 and a rectifier diode D4, the positive electrode of the rectifier diode D1 is connected to the negative electrode of the rectifier diode D2 and the forward and reverse driving power supply of the DC motor at the same time, the positive electrode of the rectifier diode D3 is connected to the negative electrode of the rectifier diode D4 and the forward and reverse driving power supply of the DC motor at the same time, the negative electrode of the rectifier diode D1 and the negative electrode of the rectifier diode D3 are both grounded, and the negative electrode of the rectifier diode D2 and the negative electrode of the rectifier diode D3 are both connected to the switch control circuit.

[0009] Furthermore, the power supply stabilizing unit includes a resistor R3, a capacitor C1 and a zener diode D5, one end of the resistor R3 is connected to the bridge rectifier unit, and the other end is simultaneously connected to the capacitor C1, the cathode of the zener diode D5 and the signal processing unit, and the other end of the capacitor C1 and the anode of the zener diode D5 are both grounded.

[0010] Furthermore, the isolation sampling unit includes a current sampling resistor and two isolation devices electrically connected to the sampling resistor and having signal separation.

[0011] Furthermore, the isolation device is an optocoupler.

[0012] Furthermore, the isolation sampling unit includes an optocoupler U1, an optocoupler U2, a resistor R4, a resistor R5, a resistor R9 and a resistor R12, pin 1 of the optocoupler U1 is electrically connected to the resistor R5 and the pin 2 of the optocoupler U2 at the same time, pin 2 is electrically connected to the resistor R4 and the pin 1 of the optocoupler U2 at the same time, pin 3 is grounded, pin 4 is connected to the resistor R12, the pin 4 of the optocoupler U2 and the signal amplification unit at the same time, pin 3 of the optocoupler U2 is grounded, the other end of the resistor R4 is connected to the resistor R9 and the switch control circuit at the same time, and the other ends of the resistor R9 and the resistor R5 are both connected to the forward and reverse drive power supply of the DC motor.

[0013] Furthermore, the signal processing unit is a small microprocessor or a discrete device.

[0014] Furthermore, the signal processing unit is a single chip microcomputer IC1, model F003.

[0015] Furthermore, the switch control circuit includes an electrically connected control switch and a switch control unit, the control switch is connected between the motor and the DC motor forward and reverse drive power supply and is electrically connected to the switch control unit, and the other end of the switch control unit is electrically connected to the signal processing unit.

[0016] Furthermore, the control switch is a relay, an electronic separation device or a switch function circuit module.

[0017] Furthermore, pin 4 of the control switch relay K1 is connected to the anode of the diode D7 and the resistor R1, pin 1 is connected to the cathodes of the diodes D7 and D4, pin 2 is connected to the forward and reverse driving power supply of the motor, pin 3 is connected to the resistor R9, and pin 5 is connected to the motor and the diode D6. The relay K1, the diode D7 and the diode D6 form a locking unit. After the driving power supply is cut off and the motor stops running, it is still in a closed loop so that it has a certain locking ability.

[0018] Furthermore, the switch control unit includes a resistor R1, a field effect transistor Q1, a capacitor C2 and a resistor R2, one end of the resistor R1 is connected to the relay, and the other end is connected to the D pole of the field effect transistor Q1, the S pole of the field effect transistor Q1, the capacitor C2 and the resistor R2 are grounded at the same time, and the G pole of the field effect transistor Q1, the capacitor C2 and the other pole of the resistor R2 are all connected to the signal processing unit.

[0019] Further, the signal amplification unit includes an operational amplifier U3, a resistor R13, a resistor R14, a resistor R15, a resistor R16, a resistor R17, a resistor R18, a resistor R19, a capacitor C11 and a capacitor C12. Pin 1 of the operational amplifier U3 is connected to resistors R16 and R17 at the same time, the other end of the resistor R17 is grounded, the other end of the resistor R16 is connected to resistor R15 and capacitor C11 at the same time, the other end of the capacitor C11 is connected to resistors R18 and R19 at the same time, the other end of the resistor R18 is grounded, the other end of the resistor R19 is connected to resistor R14 and pin 3 of the operational amplifier U3 at the same time, the other end of the resistor R14 and the resistor R13 are both connected to pin 4 of the operational amplifier U3, and the other end of the resistor R13 is connected to capacitor C12 and the signal processing unit at the same time.

[0020] Furthermore, two ends of the motor are respectively connected to two ends of a bidirectional TVS diode D6 to suppress instantaneous high voltage and protect subsequent circuits.

[0021] By adopting the above technical solution, the utility model has the following beneficial effects:

[0022] The utility model is provided with a DC motor forward and reverse driving power supply to provide an independent power supply for the circuit. After the output signal of the DC motor forward and reverse driving power supply is rectified by a bridge rectifier unit, it is stabilized by a power supply voltage stabilizing unit to obtain a DC regulated power supply to supply other units to work. The current signal is collected by a current isolation sampling unit and given to a signal amplifying unit. After the circuit signal is amplified, it is given to a signal processing unit. The signal processing unit controls a switch to control the circuit to disconnect and conduct the circuit, thereby controlling the motor to stop and start operation. When the single chip microcomputer IC1 determines that the current is too large, it sends a signal to the switch control unit to control the relay to disconnect the circuit. When the motor stops running, the motor forward and reverse drive power supply is always valid, so the signal processing unit power supply is always valid, and the switch control circuit will always keep the relay K1 in a state where pins 5 and 2 are disconnected and pins 5 and 3 are connected. After the power is cut off, the motor stops running but is still in a closed loop composed of pins 5 and 3 of K1, R9 and the motor, so it has a certain locking ability when it stops. In this way, the purpose of motor overcurrent protection is achieved and the hiccup state of the push rod is avoided. The motor stroke of the linear push rod can be controlled while the motor can be protected. It is safe and reliable, the overall circuit structure is simple, the cost is low, and it has practical promotion significance. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to make the content of the utility model easier to understand, the utility model is further described in detail below according to specific embodiments and in conjunction with the accompanying drawings, wherein:

[0024] Figure 1 This is a circuit principle block diagram of the utility model;

[0025] Figure 2 This is the single chip microcomputer interface diagram of the utility model;

[0026] Figure 3 This is a circuit diagram of the utility model. DETAILED DESCRIPTION

[0027] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0028] (Example 1)

[0029] like Figures 1 to 3The DC motor current protection circuit shown includes a DC motor forward and reverse driving power supply, a current isolation sampling unit, a bridge rectifier unit, a power supply voltage stabilizing unit, a signal processing unit, a signal amplifying unit and a switch control circuit, wherein the DC motor forward and reverse driving power supply is connected to the motor and the bridge rectifier unit at the same time, the bridge rectifier unit is connected to the power supply voltage stabilizing unit and the signal processing unit in sequence, the signal processing unit is connected to the switch control circuit and the signal amplifying unit at the same time, the output end of the switch control circuit is connected to the motor and the DC motor forward and reverse driving power supply, and the other end of the signal amplifying unit is connected to the current isolation sampling unit and the motor in sequence.

[0030] The bridge rectifier unit adopts a full-bridge rectifier structure composed of four rectifier diodes, which is not limited to being composed of discrete devices, but can also be an integrated module or other circuit modules. The isolation sampling unit includes a current sampling resistor and two isolation devices electrically connected to the sampling resistor and having signal separation. The isolation device is not limited to an optocoupler device, but also includes other isolated analog circuits or modules. In this embodiment, optocouplers are preferred, which have low cost and simple circuits. The signal processing unit is a small microprocessor or a discrete device. In this embodiment, the signal processing unit is preferably a single-chip microcomputer IC1, model F003, which is small in size, light in weight, and has high data processing efficiency. The switch control circuit includes an electrically connected control switch and a switch control unit, the control switch is connected between the motor and the DC motor forward and reverse drive power supply and is electrically connected to the switch control unit, the input end of the switch control unit is connected to the signal processing unit, and the output end is connected to the control switch. The control switch is a relay, an electronic separation device or a switch function circuit module. In this embodiment, a relay is preferably connected between the DC motor forward and reverse drive power supply and the motor, and is controlled to be opened and closed by the switch control unit.

[0031] Specifically, the bridge rectifier unit includes a rectifier diode D1, a rectifier diode D2, a rectifier diode D3 and a rectifier diode D4; the power supply voltage stabilization unit includes a resistor R3, a capacitor C1 and a voltage stabilization diode D5; the switch control unit includes a resistor R1, a field effect tube Q1, a capacitor C2 and a resistor R2; the isolation sampling unit includes an optical coupler U1, an optical coupler U2, a resistor R4, a resistor R5, a resistor R9 and a resistor R12; the signal amplification unit includes an operational amplifier U3, a resistor R13, a resistor R14, a resistor R15, a resistor R16, a resistor R17, a resistor R18, a resistor R19, a capacitor C11 and a capacitor C12. Resistor R9 is a resistor for sampling current, which needs to withstand a certain current, and is preferably a power type precision resistor. Optocouplers U1 and U2 are isolated optical couplers, and preferably have a better linearity. The operational amplifier U3 uses an ordinary operational amplifier, preferably a rail-to-rail type device, and the selection of the amplification factor depends on the strength of the current signal. The FET Q1 uses an N-channel MOSFET, which is a voltage-driven device. The power of the relay is determined by the motor load power. The microcontroller IC1 is selected with an analog-to-digital conversion peripheral, and the port of the microcontroller IC1 meets the requirements of directly driving the FET.

[0032] The cathode of the rectifier diode D1 is connected to the anode of the rectifier diode D2 and the forward and reverse driving power supply of the DC motor at the same time, the cathode of the rectifier diode D3 is connected to the anode of the rectifier diode D4 and the forward and reverse driving power supply of the DC motor at the same time, the anode of the rectifier diode D1 and the anode of the rectifier diode D3 are both grounded, the cathode of the rectifier diode D2 and the cathode of the rectifier diode D3 are both connected to the resistor R3, the other end of the resistor R3, the capacitor C1, and the cathode of the voltage regulator diode D5 are all connected to the 1st pin of the single-chip microcomputer IC1, and the other end of the capacitor C1 and the anode of the voltage regulator diode D5 are all grounded. The DC regulated power supply obtained by rectifying the output signal of the forward and reverse driving power supply of the DC motor through the rectifier bridge stack and passing through the power supply stabilization unit is used by other units.

[0033] Pin 1 of relay K1 is connected to the cathodes of D4 and D7, pin 4 is connected to the anode of D7 and one end of resistor R1, the other end of R1 is connected to the D pole of field effect tube Q1, the S pole of field effect tube Q1, capacitor C2 and resistor R2 are grounded at the same time, and the G pole of field effect tube Q1, capacitor C2 and the other pole of resistor R2 are all connected to pin 4 of single chip IC1. Pin 1 of optocoupler U1 is electrically connected to resistor R5 and pin 2 of optocoupler U2 at the same time, pin 2 is electrically connected to resistor R4 and pin 1 of optocoupler U2 at the same time, pin 3 is grounded, pin 4 is connected to resistor R12, pin 4 of optocoupler U2 and resistor R15 at the same time, pin 3 of optocoupler U2 is grounded, the other end of resistor R4 is connected to resistor R9 and pin 3 of relay at the same time, the other ends of resistor R9 and resistor R5 are connected to the forward and reverse drive power supply of DC motor, the other end of resistor R12 is connected to pin 1 of single chip IC1, and the two ends of motor are respectively connected to the two ends of bidirectional TVS diode D6.

[0034] Pin 1 of the operational amplifier U3 is connected to resistors R16 and R17 at the same time, the other end of resistor R17 is grounded, the other end of resistor R16 is connected to the other end of resistor R15 and capacitor C11 at the same time, the other end of capacitor C11 is connected to resistors R18 and R19 at the same time, the other end of resistor R19 is connected to resistor R14 and pin 3 of the operational amplifier U3 at the same time, the other end of resistor R14 and resistor R13 are both connected to pin 4 of the operational amplifier U3, the other end of resistor R13 is connected to capacitor C12 and pin 3 of microcontroller IC1 at the same time, and the other ends of resistor R18 and capacitor C12 are grounded.

[0035] The working principle of this embodiment is as follows: when the forward and reverse driving power supply of the DC motor is effective, the bridge rectifier unit obtains the power supply of the single-chip microcomputer IC1 through rectification and transformation, and the signal processing unit is powered on and starts to work. The 5th and 2nd feet of the relay are normally closed and conductive, so when the forward and reverse driving power supply of the DC motor is effective, the motor immediately has current and the motor starts to run; at this time, the current isolation sampling unit collects the real-time current signal and sends it to the signal amplification unit, and the circuit signal is amplified and sent to the single-chip microcomputer IC1 for processing. At this time, the single-chip microcomputer IC1 that has started working quickly filters the current signal, obtains the effective current signal, and then compares it according to the internally set current threshold. When the current value is greater than the threshold, the single-chip microcomputer IC1 sends a signal to the switch control unit to control the relay to disconnect the circuit and the motor stops running. At this time, the forward and reverse driving power supply of the motor is always valid, so the power supply of the signal processing unit is always valid, and the switch control circuit will always keep the relay K1 in a state where pins 5 and 2 are disconnected and pins 5 and 3 are connected. After the power is cut off, the motor stops running but is still in a closed loop composed of pins 5 and 3 of K1, R9 and the motor, so it has a certain locking ability when it stops, thereby achieving the purpose of motor overcurrent protection and avoiding the occurrence of the push rod hiccup state. It is safe and reliable, the overall circuit structure is simple, the cost is low, and it has practical promotion significance.

[0036] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A DC motor current protection circuit, characterized in that: The invention comprises a DC motor forward and reverse driving power supply and an isolation sampling unit both connected to the motor, and a bridge rectifier unit, a power supply voltage stabilizing unit and a signal processing unit connected to the DC motor forward and reverse driving power supply in sequence, wherein a signal amplification unit and a switch control circuit are respectively connected between the signal processing unit, the isolation sampling unit and the motor.

2. A DC motor current protection circuit according to claim 1, characterized in that: The isolation sampling unit comprises a current sampling resistor and two isolation devices electrically connected to the current sampling resistor and having signal separation.

3. A DC motor current protection circuit according to claim 2, characterized in that: The isolation device is an optocoupler device, an isolated analog circuit or an isolated analog module.

4. A DC motor current protection circuit according to claim 2, characterized in that: The isolation sampling unit includes an optocoupler U1, an optocoupler U2, a resistor R4, a resistor R5, a resistor R9 and a resistor R12. Pin 1 of the optocoupler U1 is electrically connected to the resistor R5 and the pin 2 of the optocoupler U2 at the same time, pin 2 is electrically connected to the resistor R4 and the pin 1 of the optocoupler U2 at the same time, pin 3 is grounded, pin 4 is connected to the resistor R12, the pin 4 of the optocoupler U2 and the signal amplification unit at the same time, pin 3 of the optocoupler U2 is grounded, the other end of the resistor R4 is connected to the resistor R9 and the switch control circuit at the same time, and the other ends of the resistor R9 and the resistor R5 are both connected to the forward and reverse drive power supply of the DC motor.

5. A DC motor current protection circuit according to claim 1, characterized in that: The bridge rectifier unit adopts a full-bridge rectifier structure composed of four rectifier diodes.

6. A DC motor current protection circuit according to claim 1, characterized in that: The signal processing unit is a small microprocessor or a discrete device. The signal processing unit is a single chip microcomputer IC1, model F003.

7. A DC motor current protection circuit according to claim 1, characterized in that: The switch control circuit includes an electrically connected control switch and a switch control unit. The control switch is connected between the motor and the DC motor forward and reverse drive power supply and is electrically connected to the switch control unit. The other end of the switch control unit is electrically connected to the signal processing unit.

8. A DC motor current protection circuit according to claim 7, characterized in that: The control switch is a relay, an electronic separation device or a switch function circuit module.

9. A DC motor current protection circuit according to claim 1, characterized in that: The signal amplification unit includes an operational amplifier U3, a resistor R13, a resistor R14, a resistor R15, a resistor R16, a resistor R17, a resistor R18, a resistor R19, a capacitor C11 and a capacitor C12. Pin 1 of the operational amplifier U3 is connected to resistors R16 and R17 at the same time, the other end of the resistor R17 is grounded, the other end of the resistor R16 is connected to resistor R15 and capacitor C11 at the same time, the other end of the capacitor C11 is connected to resistor R18 and resistor R19 at the same time, the other end of the resistor R18 is grounded, the other end of the resistor R19 is connected to resistor R14 and pin 3 of the operational amplifier U3 at the same time, the other end of the resistor R14 and the resistor R13 are both connected to pin 4 of the operational amplifier U3, and the other end of the resistor R13 is connected to capacitor C12 and the signal processing unit at the same time.

10. A DC motor current protection circuit according to claim 1, characterized in that: It also has a locking unit, which includes a relay K1, a diode D7 and a diode D6. Pin 4 of the relay K1 is connected to the anode of the diode D7 and the resistor R1 at the same time, pin 1 is connected to the cathodes of the diodes D7 and D4, pin 2 is connected to the forward and reverse driving power supply of the motor, pin 3 is connected to the resistor R9, and pin 5 is connected to the motor and the diode D6. After the driving power supply is cut off and the motor stops running, it is still in a closed loop so that it has a certain locking ability.

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