Series Connected Active Power Buffer Using a Coupled Inductor for a Grid Inverter

Abstract:
This work investigates the use and control of a coupled inductor in a series-connected active-power buffer to further reduce the size of passive components. Using the coupled inductor as a current-source, a control scheme is proposed to maintain constant dc input power, despite the output power ripple at twice the grid frequency. Feed-forward and gain compensation in control of the dc and buffer voltages ensures stable operation under transient loads. A small scale prototype with a coupled-inductor and gallium-nitride devices is presented and experimentally verified.