Current distortion improvement for power compensation with bi-directional inverter in DC-distribution system

This paper presents current distortion improvement for power compensation with a single-phase bi-directional inverter in a dc-distribution system. For achieving high power quality, the bi-directional inverter can shift the phase of inductor current to compensate reactive power when injecting power into utility grid. In the phase-shift region, the inverter needs to change the switching operation which might result in current distortion, especially near the zero crossing of the line voltage. In this paper, we propose two switching operations, including unipolar and bipolar, to shift the inductor current and improve its current distortion. Experimental results measured from a 5 kW bi-directional inverter have verified the proposed inverter operations.