Design of Control System for DC Motor Speed Regulating Device Based on Single Chip Microcomputer
In the early 1980s, brushless DC motors entered the practical stage, and square wave and sine wave brushless DC motors have been successfully researched. The concept of "brushless DC motor" has evolved from the initial DC motor with electronic phase changer to the electronically commutated motor with the external characteristics of a conventional DC motor. Nowadays, brushless DC motors integrate motors, shifting mechanisms, detection components, control software and hardware into a new generation of electric speed control systems. Brushless DC motor has the most superior speed regulation performance, mainly in: convenient speed regulation (stepless speed regulation), wide speed range, good low speed performance (large starting torque, small starting current), stable operation, noise Low, high efficiency, applications from industry to civilians are extremely extensive. Such as electric bicycles, electric cars, elevators, range hoods, soya-bean milk machines, small cleaning machines, CNC machine tools, robots, etc. Since brushless DC motors have these advantages, they were proposed at the 2004 International Motor Conference. The motor will be replaced by a brushless motor. In the field of industrial automation, the United States, Japan, Britain and Germany have realized the conversion of brushless DC motors instead of brushed motors.
DC motor has been widely used in production machinery with high speed regulation because of its wide speed regulation range, easy and smooth speed regulation, large starting, braking and overload torque, easy control and high reliability. For the adjustment of the DC motor speed, the most common method is to change the voltage of the armature end, that is, adjust the resistance of the resistor R to change the terminal voltage to achieve the purpose of speed regulation. However, this conventional speed control method is inefficient because the connected resistor consumes part of the voltage.
With the development of power electronics technology, many new armature voltage control methods have emerged, among which PWM (PulseWidth Modulation) control is a commonly used speed control method. The PWM control refers to a technique of adjusting the pulse width by adjusting the time during which the switch is turned on while maintaining the period T, thereby achieving the purpose of adjusting the motor speed. In the pulse width speed regulation system, the voltage across the armature of the motor is a pulse voltage with adjustable pulse width. When the output pulse frequency is fast enough, due to the existence of inertia, it is only necessary to change the time of power on and off according to a certain law. The speed of the motor can be reached and maintained at a stable value [2]. For the DC motor, the stepless speed regulation system consisting of PWM control technology has no impact on the DC system during start-stop, and has the characteristics of small starting power consumption and stable operation. In this paper, a DC motor speed control device based on single-chip microcomputer is designed. The AT89C2051 single-chip microcomputer with low price is the core, and the speed control device is formed together with the keyboard and motor drive circuit to realize the stepless speed regulation of the DC motor.
