Impact of Common Mode Signal Injection on the Leakage Current of a Grid-connected Transformerless Pv Inverter

Abstract

Leakage current is one of the most relevant problems in grid-connected transformerless photovoltaic (PV) inverters due to parasitic capacitance of the PV modules. This problem is directly related to the common mode voltage generated by inverter modulation. Therefore, this paper presents an analysis of the impact of the common mode signal usually injected in carrier based modulation approaches, aiming the reduction of the leakage current in three-phase grid-connected transformerless PV inverter. The resulting leakage current is analyzed for an inverter topology with a modified LCL filter, which is utilized to attenuate the high frequency components of the voltage on the PV parasitic capacitance. Experimental results are given to evaluate the performance of a 10 kW transformerless PV inverter.

Keywords

• Geometric approach
• Leakage Current
• Transformerless PV Inverter