A Carrier-Based Low Total Current Ripple Modulation Strategy for Parallel Converters With Leakage Current Attenuation

Abstract

In order to meet the high performance and low leakage current requirements in high power rating photovoltaic applications, an improved carrier-based modulation (ICBM) for parallel converters is presented in this paper. Different from existing methods which are based on PS-PWM, a proper zero-sequence modulation wave is injected into the three-phase modulation waves to achieve low total current ripple based on the root mean square value analysis of output current ripple. Aside from this, the initial phase shift angles for the carriers in each converter are modified to minimize the excitation source of leakage current, while the quality of total output current is not affected. Furthermore, the proposed ICBM is extended to parallel multilevel converters according to the vector shift principle. By using the proposed ICBM, total current ripple reduction and leakage current attenuation in parallel converters can be achieved simultaneously. Experimental results validated the correctness and effectiveness of the proposed method.