CN-114640282-B - Control circuit and method for direct current motor

CN114640282BCN 114640282 BCN114640282 BCN 114640282BCN-114640282-B

Abstract

The invention provides a control circuit and a control method for a direct current motor, wherein the control circuit is connected to a direct current power supply through setting the direct current motor, and comprises a voltage monitoring unit for monitoring the output voltage of the direct current power supply and a switching circuit for controlling the direct current motor to work, and further comprises a PWM signal output unit for outputting a PWM signal for controlling the switching circuit, and the PWM signal output unit is configured to adjust the duty ratio of the output PWM signal according to the result of the voltage monitoring unit. The motor with different resistance values can continuously work in a voltage-stabilized state, and the motor start can be identified when the load such as the motor is in heavy load or overload, so that the motor is prevented from being damaged after the load such as the motor works for a long time due to the pull-down of the power supply voltage, when the input power supply voltage is too high, the size of the input power supply voltage can be regulated, the excitation current of the motor is prevented from being increased along with the increase of the external voltage, and the iron core loss is prevented.

Inventors

HUANG ZHIXIONG
ZHANG YINGBIAO

Assignees

明达实业(厦门)有限公司
明达实业(厦门)有限公司

Dates

Publication Date: 20260421
Application Date: 20201216
Priority Date: 20201216

Claims (7)

1. A control circuit for a direct current motor is characterized in that the direct current motor is connected to a direct current power supply, the control circuit comprises a voltage monitoring unit for monitoring output voltage of the direct current power supply, a current monitoring unit for monitoring output current of the direct current power supply and a switching circuit for controlling the direct current motor to work, the control circuit further comprises a PWM signal output unit for outputting PWM signals for controlling the switching circuit, the PWM signal output unit is configured to adjust the duty ratio of the output PWM signals according to the results of the voltage monitoring unit and the current monitoring unit, the PWM signal output unit is configured to gradually increase the duty ratio of the PWM signals when the output voltage of the direct current power supply is detected to be higher than a first set voltage, and synchronously acquire current values monitored by the current monitoring unit, the PWM signal output unit judges that the direct current motor is started and stored at the moment when the output voltage is detected to be equal to or lower than the first set voltage, the PWM signal output unit is synchronously acquired, the PWM signal output unit is continuously controlled to enter a constant current power monitoring mode when the current monitoring unit is detected to be equal to or lower than the first set voltage, the PWM signal is continuously output in a constant power monitoring mode when the maximum power monitoring voltage is detected to be equal to the first set voltage, and the PWM signal is continuously output in a constant current monitoring mode when the maximum power monitoring unit is continuously constant at the first set voltage, and the maximum power monitoring value is continuously constant at the current monitoring unit is continuously output in a constant current monitoring voltage value, and the constant at the constant value is set to be constant at the maximum power voltage value, and if the voltage value is lower than the second set voltage value, judging that the carrying capacity of the power supply is insufficient, and stopping outputting the signal by the PWM signal output unit.
2. The control circuit for a direct current motor according to claim 1, wherein the switching circuit includes a transistor switch, and the PWM signal output by the PWM signal output unit is input to a control terminal of the transistor switch.
3. The control circuit for a dc motor according to claim 1, wherein the first set voltage is a difference between a static voltage and a voltage difference, the static voltage is a dc power voltage value collected and recorded in real time when the motor stops working, and the voltage difference ranges from 0.1V to 1V.
4. A control circuit for a direct current motor according to claim 3, wherein the first set voltage and the third set voltage are respectively greater than the second set voltage.
5. The control circuit for a direct current motor according to claim 1, wherein the voltage monitoring unit includes a voltage divider circuit provided with a test potential point and a first a/D sampling circuit that collects a voltage value of the test potential point.
6. The control circuit for a direct current motor according to claim 1, wherein the current monitoring unit includes a sampling resistor and a second a/D sampling circuit that acquires a current value flowing through the sampling resistor.
7. A control method for a direct current motor, the method controlling operation of the direct current motor using the control circuit for a direct current motor according to any one of claims 1 to 6.

Description

Control circuit and method for direct current motor Technical Field The invention relates to the technical field of intelligent control, in particular to a control circuit and method for a direct current motor. Background Because the load capacity of the direct current power supply is limited, the output voltage of the direct current power supply can be obviously reduced when the direct current power supply is in heavy load or overload, and the load can be greatly influenced. When the power supply voltage drops, the rotational torque of the motor is greatly reduced. If the load remains unchanged, the current of the motor must be increased substantially to produce the required torque. If the required torque exceeds the limits of the motor, the motor may be overloaded and damaged. If the voltage is too low for a long period of time, the motor may burn out due to heat generation. When the power supply voltage is lower than the rated voltage of the motor in the starting process of the motor, the rated voltage of the motor can be weakened by the magnetic field induced by the rotor, so that the current of the rotor winding and the rotating magnetic field of the induced magnetic field of the motor are weakened. Thus, both of these reductions can significantly reduce torque, and in severe cases the motor may be difficult or impossible to start. In normal operation, as the voltage decreases, the speed of the motor may slow down due to the decrease in torque and constant load. This will increase the speed of cutting the magnetic lines of force of the rotor windings, increasing the induced current and stator current. Sometimes overcurrent operation is caused, and the motor is overheated and even burnt out for a long time. When the power supply voltage is higher than the rated voltage of the motor, the exciting current of the motor increases with an increase in the applied voltage, which increases the core loss, decreases the power factor of the motor, and is disadvantageous for the operation of the motor. The detection circuit for the power supply voltage of the direct current motor in the prior art has the advantages of complex structure, higher cost, main acquisition function for the power supply voltage and calculation for other voltages, therefore, the detection circuit has no function of regulating and stabilizing voltage, and the problem that the motor is damaged due to the change of the power supply voltage in the starting and working processes of the motor cannot be solved. Therefore, a direct current motor control circuit and a direct current motor control method capable of adjusting power supply voltage to enable a system to be in a voltage stabilizing state during operation and avoid damage of a motor during starting and operation are needed to be solved. Disclosure of Invention In order to solve the technical problems that the power supply voltage of the direct current motor in the prior art does not have the function of regulating and stabilizing voltage, the motor is damaged due to the change of the power supply voltage in the starting and working processes of the motor, and the like, the invention provides a control circuit and a control method for the direct current motor, which are used for solving the technical problems. In one aspect, the present invention provides a control circuit for a dc motor, comprising the steps of: The control circuit comprises a voltage monitoring unit for monitoring the output voltage of the direct current power supply and a switching circuit for controlling the direct current motor to work, and further comprises a PWM signal output unit for outputting a PWM signal for controlling the switching circuit, wherein the PWM signal output unit is configured to adjust the duty ratio of the output PWM signal according to the result of the voltage monitoring unit. The PWM signal output unit adjusts the output voltage of the direct current power supply according to the value of the power supply voltage monitored by the acquisition voltage monitoring unit, and stabilizes the output voltage of the direct current power supply at a set voltage value. Further, the device further comprises a current monitoring unit for monitoring the output current of the direct current power supply, and the PWM signal output unit is configured to adjust the duty ratio of the output PWM signal according to the results of the voltage monitoring unit and the current monitoring unit. The PWM signal output unit adjusts the output voltage of the direct current power supply according to the value of the power supply voltage monitored by the collected voltage monitoring unit, stabilizes the output voltage of the direct current power supply within a set voltage range, monitors in real time, and determines the maximum output power of the motor according to the collected voltage value and current value, so that the motor is always in a working mode of maximum power. Further, the switching circuit includes a transis