Input current ripple cancellation of current-fed switched inverter

摘要

High boost DC-AC conversion is one of the requirements for stand-alone or grid-tied renewable applications. Current-Fed Switched Inverter (CFSI) utilizes the shoot through of the inverter legs to provide high voltage boost which can be used in low voltage renewable systems where a low voltage DC input needs to be inverted to obtain 110 V/240 V AC. Due to the presence of inductor on the input side, CFSI draws a continuous current from the supply which makes it suitable for renewable applications. However in high boost operating mode, the inductor current ripple of CFSI becomes significantly high as it increases in proportion with its boost factor. In this paper an input current ripple cancellation network (RCN) is introduced which consists of a small inductor and a small capacitor while the main inductor is replaced by a coupled inductor. As the RCN consists of only a small inductor and capacitor, it doesn't increase the overall weight and size of the system. In this paper, the condition for input current ripple cancellation is derived from the state equations of the inverter. The steady-state analysis and PWM strategy is explained in details. A 29 V DC to 110 V (rms) AC, 300 Watt experimental prototype is build to validate the proposed RCN which shows strong correlation with the theoretical analysis.