Novel PWM scheme with multiphase SVPWM for reducing current ripple

This paper proposes a novel pulse width modulation (PWM) scheme for multiphase space vector pulse width modulation (MSVPWM), which is used in sensorless control of interior permanent-magnet synchronous motor drives. The estimation of the rotor position is based on magnetic saliency and employs high-frequency components of voltage and current which are excited by a MSVPWM pattern. The difference between the instantaneously applied voltage vector and the reference voltage vector causes current ripples. Since six active voltage vectors are generated during a PWM period, the sequences of the six error voltage vectors lead to different types of current ripples. In this paper, the proposed PWM scheme employs six sequences based on angle range to reduce line current ripple. Experimental results confirm that the proposed PWM scheme leads to significant reduction in harmonic current while maintaining high performance of sensorless estimation despite the reduced current ripple.