Induction motor drives for domestic appliances

The three-phase induction motor has been adopted for the drive described in this article. The target performance of the drive is based on the requirements for a commercial front-loading washing machine, with a load capacity of 11 lbs., which has an inner drum size of 460 mm. The production washing machine uses a universal motor drive, fed with AC from a phase-controlled triac. The motor rotates the drum through a belt drive, and the pulley ratio is 15:1. The aim is to design the induction motor drive to meet the torque speed needs. The base speed range is 1:14.5 for a wash speed of 55 r/min and a spin speed of 800 r/min. Increased spin speeds are desirable, requiring an extended speed range. Also, a slower “gentle wash” speed may be used. By applying variable frequency, variable voltage with slip control these requirements can be met by a high-speed induction motor operating with a suitable pulley ratio. The experimental drive comprises a high-speed three-phase induction motor fed by an inverter