Six-Phase Drives with Combined Synchronized Space-Vector Modulation

The paper presents analysis of operation of dual three-phase (six-phase) power conversion systems, controlled in accordance with combination of continuous and discontinuous schemes of synchronized pulsewidth modulation (PWM). Topology of six-phase drive includes six-phase inverter feeding asymmetrical six-phase machine which is characterized by two sets of three-phase windings that are spatially shifted by 30 electrical degrees. Algorithms of synchronized PWM provide continuous synchronization of the output voltage of six-phase inverter during the whole control range. Space-vector approach for determination of the pulse patterns provides minimum number of switchings and minimal switching losses. Simulations give the behaviour of the six-phase systems with synchronized space-vector modulation. The phase voltages of six-phase drives with synchronized PWM have quarter-wave symmetry, and its spectra do not include even harmonics and subharmonics, which is especially important for high power/current applications.