Transformerless Z-Source Four-Leg PV Inverter With Leakage Current Reduction

Due to the lack of electrical isolation, the leakage current is one of the most important issues for transformerless photovoltaic (PV) systems. In this paper, a new modulation strategy is proposed to reduce the leakage current for a Z-source four-leg transformerless PV inverter. First, the common-mode loop model is presented. And then the common mode voltage behavior and the effect of factors on the leakage current are discussed. A new modulation strategy is proposed to achieve the step-up function and constant common mode voltage. Therefore, the leakage current can be suppressed effectively. Finally, the proposed strategy is digitally implemented and tested on the TMS320F28335 DSP and XC3S400 FPGA controlled hardware platform. The experimental results verify the effectiveness of the proposed solution.