A differential-mode current-sourced high-frequency-link photovoltaic inverter

A differential-mode current-fed zero-current-switching (ZCS) based voltage-doubling photovoltaic (PV) inverter is presented. This inverter has the following features: 1) it can boost a low-voltage (30-60 V) input to a 120-V/60-Hz output; 2) it does not require a 60-Hz transformer; 3) it does not require a front-end dc/dc converter; and 4) the topology has inherent voltage boost/gain property thereby reducing the reliance on the transformer turns ratio. The inverter requires a smaller high-frequency transformer because a) the inverter switches at 100-kHz, b) the transformer voltage and current are bipolar in every switching cycle, and c) only half the input current flows through the transformer at any given instant of time. To maintain the THD within the acceptable limit, a harmonic compensation control using a proportional-resonant (PR) controller is implemented. Analysis, design, and simulation results of the proposed inverter are presented.