A low frequency input current reduction scheme of a two-stage single-phase inverter with DC-DC boost converter

초록

A two-stage single-phase grid-connected inverter has 120Hz component in input current as influence of pulsating output power at double of the grid frequency. The 120Hz component of input current has to be reduced or eliminated because low frequency current can damage a source or reduce efficiency in the photovoltaic, fuel cell and battery systems. Prior studies which deal with reduction of the 120Hz component have their own limits. Thus, it is unavoidable to use a bulky dc link capacitor or a high gain controller. This paper proposes the feed-forward compensation for current control of the boost converter in a two-stage single-phase grid-connected inverter. The feed-forward compensation substantially removes 120Hz component from the input current without a bulky dc link capacitor or a high gain current controller as removes the disturbance of dc link voltage from the current control. Removal of the disturbance and reduction of the 120Hz component of input current are analyzed with a small-signal model and bode plot. Simulation and experimental results are provided for validation.