Evaluation of efficiency and power quality for a two-phase asymmetrical induction motor drive

Variable frequency drives for two-phase low power induction motors operating from the single-phase ac utility have received much attention in domestic and commercial applications. A commonly used scheme for speed regulation is the volt per hertz control, where both the frequency and voltage applied to the motor are adjusted to match the rotor speed command. In this paper we evaluate the performance of such a drive system in terms of its energy efficiency and its effects on power quality on the supply side. It is found that the loading for optimum power efficiency is strongly affected by the stator fundamental frequency, while power quality improves at higher torque outputs.