A Half-Bridge PV System with Bi-direction Power Flow Controlling and Power Quality Improvement

In this paper a half-bridge photovoltaic (PV) system is proposed, which can not only process power bi-directionally but improve power quality. According to varying insolation, the system conditions real power for dc and ac loads to accommodate different amount of PV power. Furthermore, the system eliminates current harmonics and improves power factor simultaneously. As compared with conventional PV inverter, the total number of active switches and current sensors can be reduced so that its cost is lowered significantly. For current command determination, a linear-approximation method (LAM) is applied to avoid complicated calculation and achieve maximum-power-point tracking (MPPT) feature. For controlling, a direct-source-current-shaping (DSCS) algorithm is presented to shape the waveform of line current. Simulation results and practical measurements demonstrate the feasibility of the proposed half-bridge PV system.