Active Common-Mode Filter for Ground Leakage Current Reduction in Grid-Connected PV Converters Operating with Arbitrary Power Factor

This paper proposes a solution for reducing the ground leakage current in transformerless single-phase grid-connected PV converters. This is obtained with the introduction of an active common-mode filter able to compensate for variations of the output common-mode voltage of the power converter. The active common-mode filter is applied to a widespread and efficient full-bridge driven by a 3-level PWM, allowing the power converter to operate with low ground leakage current and with arbitrary power factor. After showing the desired voltage waveform for common-mode voltage compensation, this paper presents the design guidelines for the needed additional magnetic component together with the power losses considerations for all the devices added for the proposed solution. Experimental results show the performance of the proposed solution in terms of ground leakage current reduction, effectiveness of the dead-time compensation, THD of the injected grid current and power losses.