The Development Of Medium Frequency Power Supply Of Thyristor With Single Chip Control

The medium frequency power supply of thyristor is an equipment to heating workpiese by whirling current. It has been widely used in industrial cooking because of its simplicity, high efficiency and convenience. However, this kind of power supplies have some defects, such as harmonic, starting up, power regulating, control systems. This paper discusses a new scheme, including BUCK circuit, softly starting up with sweeping-frequency, impedance PI regulation and single chip control system, to improve the performance of power supply. A model machine has been made according to the design, and experiments have been done. The results show that the design is reasonable, reliable and useful.This paper is divided in six chapters, including the medium frequency power supply of thyristor's theory, design, regulation strategy, control system, experiments and conclusion. The first chapter analyzed the work theory of rectifier and converter, and chiefly discussed the harmonic content of BUCK circuit and the scheme of softly starting up with sweeping-frequency. The second chapter introduced the main circuit design of this paper, and chosen the parameter of the devices in the circuit. The third chapter analyzed the theory and course of PI regulation, which inchide voltage, current and impedance. The algorithm routine has also been given, and emulated by MATLAB. The forth chapter introduced the design of control systems, which is made up of hardware and software. The fifth chapter presented the experiments that has been done on the model machine, and analyzed the results. The last chapter drew the conclusion of this paper.