Single-Step Commutation Method for Three-Phase to Single-Phase Matrix Converter

Abstract

This paper proposes a single-step commutation method based on an output current direction estimation for a three-phase-to-single-phase matrix converter. Conventional four or two-step commutation causes a commutation failure due to the detection error of grid voltages. In addition, an input current is distorted due to an output voltage error in the low modulation index on a three-phase to single-phase matrix converter. A zero vector to decrease an output current up to zero is proposed to achieve single-step commutation under all region. In the proposed single-step commutation, by modulating only one of two devices in a bi-directional switch and utilizing a zero vector, the commutation failures are avoided completely regardless of the voltage detection error. As experimental results, the input current distortion is 2.3% at 10 kW with the proposed single-step commutation. The input current THD in low modulation index is reduced by 34.9% in comparison with the conventional four-step commutation. The proposed single-step commutation has a considerably simple commutation algorithm.