Patent ID: 8817508

Claim:
A bidirectional inverter for a renewable energy storage system, the bidirectional inverter being configured to provide power from a direct current (DC) link to an electric power system or to provide power from the electric power system to the DC link, the bidirectional inverter comprising: a pulse-width-modulation (PWM) signal provider for providing a PWM signal; a push-pull inverter coupled to the PWM signal provider and the DC link; and an offset voltage provider coupled to the push-pull inverter and the electric power system, and configured to level-shift an AC input voltage, and wherein the offset voltage provider is configured to provide an offset voltage to the electric power system, the offset voltage being a sum of a negative offset voltage and the AC input voltage, wherein the AC input voltage is an AC voltage from the push-pull inverter, and wherein the negative offset voltage level-shifts the AC voltage from the push-pull inverter in a negative direction by one half of the AC voltage.