A Zero Common Mode Voltage PWM Scheme with Minimum Zero-Sequence Circulating Current for Two-Parallel Three-Phase Two-Level Converters

This paper introduces a PWM scheme for both common mode voltage elimination and zero-sequence circulating current suppression. Our approach began with analyzing the relationship among basic vectors, common mode voltage elimination, and zero-sequence circulating current suppression to select optimal vectors that support both objectives. Following this, we arranged these selected vectors strategically to achieve simultaneous common mode voltage elimination and zero-sequence circulating current suppression, resulting in six optimal vector sequences for each 60° sector. Considering the redundancy of the proposed vector sequences, each 60° sector is subdivided into four subsectors for optimal performance, each employing its optimal vector sequences. Additionally, we implemented a carrier-based modulation scheme to simplify the implementation of the proposed vector sequences. The vertical and horizontal comparisons with the existing common mode voltage elimination method and other representative zero-sequence circulating current suppression modulation schemes reveal that our method attains both common mode voltage elimination and zero-sequence circulating current suppression, outperforming existing methods. Experimental results further confirm the effectiveness of our proposed approach.