An Improved Asymmetric Modulation of Current-Source Rectifier With CM Filter for Low Voltage Stress on Switching Devices

Common-mode (CM) filters are usually utilized in high power density three-phase current-source rectifier (3ph-CSR) to suppress the CM noise in the input currents. However, when CM filters are utilized, the inductor currents at the positive and negative ends of the dc side of 3ph-CSR are unequal, which brings high voltage stress on switching devices. To reduce the voltage stress on the switching devices, an improved asymmetric modulation is proposed in this letter. In the proposed asymmetric modulation, two switching devices are always turned on in each sector, which clamps the voltage of the switching devices to the peak of the input line voltages. A 1 kW experimental prototype of the 3ph-CSR is built to verify the analysis results.

I. Introduction

Three-phase current-source rectifier (3ph-CSR) features low distortion of ac input currents and inherent start-up inrush current limiting capability. The 3ph-CSR, also known as the three-phase buck rectifier (3ph-BR), has been successfully used in more electric aircraft (MEA) [1], [2] and electric vehicle charger [3]. For 3ph-CSR, the high voltage stress on switching devices not only brings high power loss but also makes selection of switching device difficult. Besides, the switching devices with high voltage rating means a high cost of 3ph-CSR. Therefore, some research works on reducing the voltage stress on switching devices have been performed to improve the performance of 3ph-CSR [4], [5], [6], [7].