High Gain, High Frequency Link DC-AC Converter with Hybrid SPWM Scheme

Abstract

A high gain, single-stage DC-AC converter with high frequency AC link is proposed in this paper. The single-stage DC-AC converter has the advantage of high efficiency, less component count and high power density. The proposed converter consists of a high frequency switching buck-boost bridge followed by a low frequency switching cycloconverter. A hybrid sinusoidal PWM switching scheme is used for the buck-boost bridge to control the output and to mitigate the DC-current in the transformer primary winding. In the proposed converter, soft transition is achieved in all the devices. The steady-state voltage gain achieved is twice that of the conventional H-bridge phase-shift converter. The input current is continuous in the proposed converter which reduces the DC bus capacitor requirement for solar PV fed applications. The steady-state analysis with the modes of operation of the proposed converter are presented. A 2 kVA proposed converter feeding the R and RL load is designed and implemented in the simulations and the analytical model is verified. The comparison studies of the proposed converter with the topologies in literature are presented.