Improvement in THD for PWM based AC-DC Converter using Switching Capacitor Technique

A novel single stage high step up full bridge AC-DC converter, based on the concept of switched capacitor topology existing in high step up DC-DC converter, is proposed in this work. In switched capacitor technique, capacitors on secondary side are charged in parallel during the switch-off period, by the energy stored in the coupled inductor, and are discharged in series during the switch-on period to achieve a high step-up voltage gain. The switched capacitor technique meant for high voltage gain is discussed in many conventional DC-DC converters. The proposed AC-DC full bridge converter converts the input AC voltage into DC and boost with a high voltage gain in a single stage. For high voltage gain AC-DC converters many techniques are proposed in literature. In this work, switched capacitor technique is used in AC-DC converter is a novel method for attaining high voltage gain. Open loop control of the proposed converter is done by using PWM control. The closed-loop control methodology is utilized in the proposed scheme to overcome the voltage-drift problem of power source under the variation of loads. The operating principle, steady state analysis and design of proposed single stage high step up AC-DC converter is carried out. Simulation results, using MATLAB, are carried out for proposed AC-DC converter.