Neutral-point-clamped inverters with hybrid PWM for symmetrical six-phase motor drive

Specialized combined schemes of synchronized pulsewidth modulation (PWM) have been applied for control of symmetrical dual three-phase (six-phase) drive on the base of two neutral-point-clamped inverters, providing both common-mode voltage cancellation and continuous synchronization of the output voltage of inverters during the whole control diapason. Simulations give the behaviour of six-phase systems with synchronized space-vector modulation. It has been shown, that combined schemes of synchronized PWM provide better spectral composition of the useful components of the phase voltage in comparison with inverters´ control on the base of two identical PWM schemes. Phase voltages of symmetrical six-phase drives with synchronized PWM have symmetry during the whole control range including overmodulation, and their spectra do not contain even harmonics and subharmonics, which is especially important for high power/high current applications.