DC motor has good starting and braking performance and is suitable for smooth speed regulation in a wide range. It has been widely used in many electric transmission fields that need speed regulation or fast forward and backward direction. From the control point of view, DC speed regulation is also the basis of AC drive system. The control of early DC engine is based on analog circuit, which consists of operational amplifier, nonlinear integrated circuit and some digital circuits. The hardware part of the control system is complex, the function is single, the flexibility is poor and the debugging is difficult, which hinders the development and application of DC motor control technology. With the rapid development of single chip microcomputer technology, many control functions and algorithms can be completed by software technology, which provides greater flexibility for the control of DC motor and makes the system achieve higher performance. Using single-chip microcomputer to form a control system can save human resources, reduce system cost, and thus effectively improve work efficiency [1].

The main circuit of this design adopts the power supply scheme of thyristor three-phase fully controlled bridge rectifier circuit, and the control circuit realizes the system function through software to replace the traditional double closed-loop speed regulation system. The system replaces the speed regulator, current regulator, trigger, zero lock unit and current adaptive regulator in the original analog system with single chip microcomputer and external expansion equipment, which makes the DC speed regulation system digital [2].