A novel SVM based gating strategy for high-power current-source converters with reduced common-mode voltage and improved harmonic performance

Abstract

In high-power medium-voltage applications, the device switching frequency of current-source converters (CSCs) is usually limited to several hundred Hertz. The selective harmonic elimination (SHE) is preferred due to its superior harmonic performance. However, the valid solution for the switching angles of SHE may not exist in some cases. The converter may switch to trapezoidal pulse-width modulation (TPWM) or space vector modulation (SVM) for solution. The TPWM and SVM schemes can provide variable modulation index control but the output current contains low-order harmonics with high magnitudes. In addition, compared with SHE and TPWM, the peak value of the common-mode voltage (CMV) could be doubled with conventional SVM because of the introduction of zero vector. In this paper, a novel SVM based modulation strategy is proposed for CSCs. Compared with the conventional SVM, the proposed method provides a lower CMV magnitude. In addition, the low-order harmonic contents can be reduced compared with the TPWM or the conventional SVM. Simulation and experimental results are provided to verify the proposed concepts.