标题：Dual Half-Cycle-Bridges Single-Phase Photovoltaic Inverter
作者：Zhou, Liwei; Gao, Feng; Xu, Tao; Duan, Wen
作者机构：[Zhou, Liwei; Gao, Feng; Xu, Tao; Duan, Wen] Shandong Univ, Sch Elect Engn, Jinan 250100, Peoples R China.
会议名称：IEEE Energy Conversion Congress and Exposition
会议日期：SEP 20-24, 2015
来源：2015 IEEE ENERGY CONVERSION CONGRESS AND EXPOSITION (ECCE)
关键词：grid connected inverter; common mode voltage; unipolar switching; strategy
摘要：In a transformer-less photovoltaic (PV) grid connected system, there exists a galvanic connection between the grid and the PV array. Without any transformer in the inverter, common-mode leakage currents can flow through the stray capacitance between the PV array and the ground. This paper first analyzes the equivalent common-mode circuit of single-phase inverter, and compares several single-phase inverters with constant common-mode voltage. This paper then proposes a novel dual half-cycle-bridges (DHCB) single-phase PV inverter with low conduction losses. A novel hybrid SPWM modulation method is introduced to achieve the minimum switching losses under any power factor operation. Next, adding a neutral point clamped circuit to the DHCB inverter, the common-mode voltage can be clamped to half of DC voltage firmly. Finally, simulation and experimental results have validated the theoretical findings.