Design of Common and Differential Mode Filters for Single-Phase Full-Bridge Photovoltaic Inverters

Abstract

Photovoltaic arrays have high parasitic capacitance between positive/negative poles and earth. Therefore, conventional single-phase full bridge inverters with unipolar modulation are not suitable for applications in photovoltaic inverters because they have leakage currents higher than the limits acceptable by the standards. Additionally, high common mode currents tend to result in electromagnetic noise of significant magnitude. This paper proposes an integrated methodology for common and differential mode filter design for single phase full-bridge photovoltaic topology with a LCL filter. The differential mode filter is designed to meet the constraints of harmonic current distortion, while the common mode filter is designed to suit the ripple of common mode current and the filter quality factor to the design constraints. Simulation results show that the proposed methodology is simple and effective.