Abstract
This article introduces the speed control principle of DC motor, expatiates on the speed control system taking PIC16F877 SCM as the main control component, utilizes the characters of catching module, comparing module and analog-to-digital conversion module in PIC16F877 SCM to be the trigger circuit, and gives the program flow chart. The system has many advantages including simple structure, synchronization with the main circuit, stable shifting phase and enough shifting phase range, the control angle of 10000 steps, stepless smooth control of motor, steep pulse front edge, enough amplitude value, setting pulse width, good stability and anti-jamming, and cheap cost, and this speed control system with good practical values can be realized easily.
Highlights
Work principle of the systemThe system is mainly composed by master switch, motor exciting circuit, thyristor speed control circuit (including tachometer circuit), rectifying filter circuit, flat wave reactor and discharge circuit, energy consumption braking circuit, and the system adopts the closed loop PI regulator to implement control
The quick development of electric technology makes the speed control of DC motor gradually translate from analog to digital, and at present, the KZ-D towage system which extensively adopts the thyristor equipment in the electrical towage control systems to supply power to electromotor has replaced cumbersome F-D system of generator-electromotor, and especially the application of SCM technology makes the speed control technology of DC motor enter into a new phase
The control circuit adopting analogy or digital circuit can be implemented by SCM
Summary
The system is mainly composed by master switch, motor exciting circuit, thyristor speed control circuit (including tachometer circuit), rectifying filter circuit, flat wave reactor and discharge circuit, energy consumption braking circuit, and the system adopts the closed loop PI regulator to implement control. When the master switch closes, the single-phase AC obtains continual current with small pulse through the control of thyristor speed control circuit, and bridge rectifier, filtering and flat wave reactor for the motor, and at the same time, through the rectifying of exciting circuit, AC makes the motor obtain excitation to begin to work. The speed in the regulation trigger circuit sets the potentiometer RP1 to make the control angle output by PIC16F877 decrease when AN1 input voltage decreases, and the flow angle of thyristor increases with that, and the output voltage of main circuit increase, and the motor speed increases, and the output voltage of tachometer circuit increases, and the motor stably runs in the setting speed range through the function of PI regulator
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