Analysis and Control of Two Switches AC Chopper Voltage Regulator

Abstract:- In this paper, an improved topology of Buck type AC chopper voltage regulator and its control strategy are proposed. This converter only using two power switches is low cost, easy implemented and the phase synchronized circuit is not needed. The current path is provided in dead-time period by using simple snubber circuit. The over-voltage protection varistor is also applied to absorb the voltage spikes which may destroy the power switches. The voltage spikes in dead-time mode commutation are greatly reduced and the power switches are protected. Furthermore, the feedforward and feedback control strategy is proposed to suppress fluctuations and eliminate the harmonic components caused by power quality problems of the input voltage. The proposed converter could realize wide range voltage regulation with high power transfer efficiency and low total harmonic distortion. The steady-state equivalent circuit and the input power factor are derived through theoretical analysis. The output filter design method is also presented. Based on the theoretical analysis and calculation, an experimental prototype is setup. The simulation and experiment results verify the validity of the proposed design