High-frequency Soft-switching Rectifier Voltage Regulator Circuit Technology And Power Factor Crection

The chopper power regulation of induction heating power supply is usually adopted by hard chopper, which limits the improvements of power and frequence because of the significant loss of power devices. It is urgent requirment of achieving to the high-efficiency and high power factor.According to the need of the subject, this paper gives the detail analysis of the series resonant inverter and parallel resonant inverter, and compares their characteristics, and chooses series resonant inverter as the induction heating power supply's inverter. In order to overcome the disadvantage of the losses of power devices, a novel soft-switching Buck converter is proposed to adjust the power of induction heating power supply.The proposed novel soft-switching Buck converter is analyzed in detail by thoery and simulation, the main switching turns on and off with zero voltage and the auxiliary switching turns on and off with zero current. All of the diode were under soft condition, and switching losses are reduced. The main circuit contains three-phase uncontrolled rectifier, DC soft chopper and series resonant inverter, then the parameter of components are calculated and the components are selected. Taking AC harmonic as the research subject, this paper uses Fourier series to analyze the harmonic of equivalent model of induction heating power supply. According to the project and considering the complexity and cost of the whole system, three-phase uncontrolled rectifier with inductor and capacitor combinating of chopper circuits are selected to reduce harmonics and improve power factor.The simulation results show the proposed novel soft-switching Buck converter achieve the desired soft-switching results, the additional voltage and current stresses on the main switching do not take place and the switching losses are reduced, which verified the theoretical analysis and designed scheme. An experimental device has been designed, and the output voltage and current were measured, the waveforms met the requirements and proved the device was stable. The input voltage and current of uncontrolled single-phase and three-phase rectifier with inductance and capacitance were measured, and the actual waveforms were consistent with the theoretical analysis basically.