A novel single-stage isolated PWM half-bridge microinverter for solar photovoltaic modules

This paper presents a novel single-stage isolated pulse-width-modulated (PWM) half-bridge cyclo-converter based microinverter for photovoltaic (PV) application. The proposed topology is a single stage microinverter with reduced number of components, and provides high frequency (HF) transformer isolation. This microinverter can be operated both as grid-connected and stand-alone off-grid inverter. The secondary side of HF transformer is interfaced with cyclo-converter stepping down the frequency to line-frequency (50 Hz). Sinusoidal-pulsewidth- modulation (SPWM) is incorporated for this novel design on primary switches and uniquely all the four switches on secondary side of the HF transformer are switched at line frequency thus reducing switching losses on the secondary side. The energy stored in the leakage inductance of HF transformer is used for zero voltage switching (ZVS) of primary switches thus reducing switching losses. An experimental prototype rated at 250 W has been designed, developed, and tested in the laboratory to verify operation of the proposed topology.