Control and design of a four-switch inverter with reduced low-frequency input current ripple and capacitance requirement: A comparative study

A large amount of ripple at twice the output frequency will emerge in the input current at dc side due to the pulsating output power in a single-phase dc-ac power conversion system. In this paper, a current-source-type four-switch inverter based on switch multiplexing technique is studied, which can realize the reduction of input low-frequency current ripple as well as dc capacitor requirement. To get a more complete understanding of its performance, a full comparison is presented between it and the traditional two-stage single-phase inverter in the aspects of operation principle, equivalent circuit model, power decoupling method, key circuit parameter, and system efficiency. The four-switch inverter is proved to be input-ripple-free and more efficient, and its size is much smaller because the dc capacitor can be reduced significantly. Finally, experimental results performed on two single-phase inverter prototypes verify the analysis and conclusions.