n improved space vector modulation for a three-to-seven-phase matrix converter with reduced number of switching vectors

Abstract

This paper proposes a space vector modulation (SVM) scheme for a three-to-seven-phase matrix converter (MC), feeding a variable-voltage variable-frequency multiphase drive. The main feature of the proposed technique is that it utilizes only 129 out of 2187 possible active space vectors for a successful ac-ac power conversion. Since the number of vectors is significantly reduced, the switching patterns are simplified, and the execution time of the algorithm is shortened. Despite the drastic reduction in the number of active vectors, it is found that there is no significant degradation in the performance of the MC. Furthermore, the SVM also produces balanced sinusoidal input currents with a unity power factor over a wide operational frequency range (1-110 Hz). In this paper, the theoretical analysis is supported by simulation and validated using a hardware prototype. The output voltage can reach up to 76.93% of the input voltage, which is the maximum physical limit of a three-to-seven-phase MC. In addition, it exhibits a better harmonic profile than the carrier-based modulation scheme; the total harmonic distortion for the output voltage waveform is measured to be below 5% over the entire operating frequency range.