Common-mode voltage characteristics of matrix converter-driven AC machines

This paper investigates the common-mode voltage characteristics induced by PWM switching of the Matrix Converter (M×C). Since the three-phase matrix converter has 27 output voltage vectors available, different common-mode voltage patterns exist even with the same line-to-line output voltages. High common-mode dv/dt contributes high leakage currents to the ground through the parasitic capacitances. Since output voltage vectors can be grouped according to the magnitude of common-mode voltage, PWM patterns should be designed to select the low common-mode voltage vector groups satisfying the requirement of output voltages and input currents. In this paper, practical PWM patterns of M×C are illustrated and their common-mode voltage characteristics are presented. A new PWM method is proposed and discussed considering both low common-mode voltage and low dv/dt in the PWM pattern. The results are also compared with the data obtained by the Voltage Source Inverter (VSI).