Power Factor Operation of a Boost Integrated Three-Phase Solar Inverter using Current Unfolding and Active Damping Methods

This paper proposes a three-phase solar inverter with integrated boost function. The circuit operating principle is based on current unfolding and injection method. This approach requires only two high frequency switches for the boost function as well as shaping its output currents, thus leading to a significant reduction in switching losses. Other switches only operate at line frequency to unfold the output currents to sinusoidal three-phase currents, and thus can be optimized to reduce conduction losses. The proposed inverter therefore could deliver high efficiency. This paper discusses the basic operating principle and control method for the inverter. The paper proposes an active damping method to overcome intrinsic oscillation due to overlapping time in switching operation. It also shows that the inverter is capable of supplying reactive power up to a limit of 0.866 power factor. Stable operation of the proposed inverter is confirmed by both simulation and experiment.