A minimum-switch direct-link drive with common-mode voltage suppression and active filtering for open-end winding AC machines

Conventional pulse-width modulated inverters cause switching of common-mode voltage at the terminals of ac machines, which result in undesirable bearing currents and damage to the bearing. This paper presents a two-level indirect-matrix converter-based direct-link drive for three-phase open-end winding ac machines. The proposed topology suppresses common-mode voltage, outputs up to 1.5 times the peak input phase voltage and has controllable input power factor using a novel active filtering mechanism. Simulation results are presented that verify the operation of the proposed topology.