Improvement of two grid power factor control methods for matrix converter open‐end‐winding drive with common‐mode voltage elimination supplied by unbalanced grid

Abstract

Abstract This paper investigates space‐vector‐modulation (SVM) technique that uses only rotating space vectors to drive a direct matrix converter (DMC) with zero common‐mode voltage (CMV). Two methods for controlling grid power factor have been proposed in the literature for such a drive. Until now, analysis has been limited to balanced grid conditions. However, total harmonic distortion (THD) of grid currents significantly increases under unbalanced conditions. Hence, the aims of this paper are: (1) derivation of DMC model consisting of general equations for output voltages and input currents, written in the complex form. (2) Analysis and comparison of two existing methods for grid power factor control under balanced grid conditions, by using the previously derived model. (3) Proposal of extended versions of both methods in order to improve converter's performance under unbalanced grid conditions. The proposed control strategy aims to achieve sinusoidal currents and maintain the same power factor on the grid side while completely compensating grid unbalance on the load side. (4) Determination of the maximum transfer ratio under balanced and unbalanced grid conditions. Experimental results with Hardware In the Loop (HIL) are provided to verify the theoretical analysis and effectiveness of the proposed control strategy.