Design and efficiency comparison of electric motors for low power variable speed drives with focus on permanent magnet motors

Low power industrial motor drives are dominated by the induction motor, followed by permanent magnet (PM) motors. This paper presents an efficiency comparison of these motors from measurements on six 100 W motors of comparable size, fed by VSI PWM DC-link inverters. The focus is on the PM motors as these seem to offer the highest efficiency at low power ratings. To set the PM motors in perspective, comparison is made to a 2 pole, 3 phase, induction motor.