Closed-Loop Common Mode Current Mitigation for Transformerless Current-Source Soft Open Points

Lihui Wang

doi:10.1109/tpel.2026.3719375

Closed-Loop Common Mode Current Mitigation for Transformerless Current-Source Soft Open Points

2026-08-03

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DOI：10.1109/tpel.2026.3719375

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Compared to voltage-source converters (VSCs), current-source converters (CSCs) are characterized by simple topology, inherent DC short-circuit limitation, and high-quality input-output waveforms. However, the mechanism of common-mode currents (CMCs) generation in CSCs differs from that in VSCs, making the mitigation of CMCs in transformerless current-source soft open points (CS-SOPs) more challenging. To address this issue, a closed-loop approach based on optimal vector approximation space vector modulation (SVM) strategy is proposed. First, a common-mode equivalent circuit is established to derive the relationship between the CMC and common mode voltage (CMV). Then, an optimal vector approximation SVM is proposed, which achieves average CMV direct regulation through the optimal selection of zero vectors during each sampling period. Furthermore, the method effectively mitigates CMCs through a closed-loop control. Moreover, power loss analysis of the CS-SOP confirms that the proposed strategy incurs negligible additional losses and maintains high efficiency, ensuring its practical viability. Finally, experimental results demonstrate the effectiveness of the proposed method.

Keywords:

Common mode current (CMC)

current-source converter (CSC)

space vector modulation (SVM)

transformerless soft open points (SOPS)

Closed-Loop Common Mode Current Mitigation for Transformerless Current-Source Soft Open Points

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