Structures and modulation algorithms of direct ac/ac converters with two legs and three legs for two-phase systems

Abstract

Two-phase ac/ac matrix converter configurations are presented based on direct power conversion processes from three-phase input ac supplies to two-phase output ac loads. Two types of two-phase matrix converter topologies, utilizing the standard matrix converter configuration, are introduced with two-leg and three-leg based structures. Pulse width modulation (PWM) strategies with high-frequency composition for the two-leg and the three-leg based two-phase matrix converters are developed to synthesize sinusoidal output waveforms of two-phase loads from time-varying input ac voltages. Grounded on the developed modulation algorithms, the presented matrix converters directly generate controllable two-phase output voltages from sinusoidal input voltages with no intermediate dc conversion and concomittant dc-link elements. The proposed matrix converters can provide sinusoidal output current/voltage waveforms with independently controlled magnitude and 90 degrees phase angle to two-phase loads. Thus, the converters are effective for both balanced and unbalanced two-phase loads. The presented two-phase operations with the standard matrix converter structures add the versatility for the matrix converter systems to function in multi-phase loads as a universal converter. Simulation and experimental results are presented to verify the developed modulation techniques and the converter configurations for the two-phase matrix converters.