A minimized DC-bus capacitor with active combinational decoupling method for DC-AC application

This paper shows a combinational decoupling method to minimize dc-bus capacitance and improve power density for DC to AC applications, especially for single-phase inverters. The proposed method is combined with in-series structure and in-parallel structure together with power equations analyzed. The detailed control strategy is given. The simulations are conducted via PLECS software to prove the theoretical proposal. Furthermore, a 2kW prototype is built. The power density of this prototype is ~55W/inch³. The decoupling capacitance is minimized ~2/3 that of traditional series voltage compensator method. The experiments are further finished and the efficiency of the prototype is ~ 95%. Besides, the issues for 2^nd order decoupling method is investigated and an instantaneous pulse decoupling method is discussed in this paper. A brief comparison of these two methods are summarized.