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

In order to meet the high current quality and low leakage current requirements in high power rating photovoltaic applications, an improved carrier-based modulation (ICBM) for parallel converters is presented in this article. Different from existing methods which are based on phase-shifted pulsewidth modulation, a proper zero-sequence modulation wave is injected into the three-phase modulation waves to achieve a low total current ripple based on the root mean square value analysis of the 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.

Automated summary

This article presents an improved carrier-based modulation (ICBM) for parallel converters to meet the high current quality and low leakage current requirements in high power rating photovoltaic applications. By injecting a proper zero-sequence modulation wave into the three-phase modulation waves, a low total current ripple is achieved based on the root mean square value analysis of the output current ripple. The initial phase shift angles for the carriers in each converter are modified to minimize the excitation source of leakage current without affecting the quality of total output current. The proposed ICBM is also extended to parallel multilevel converters according to the vector shift principle, enabling simultaneous total current ripple reduction and leakage current attenuation.