The challenges of using variable-speed motor drives in appliance applications

Consumer applications, and in particular appliances such as washers, dryers, and air conditioners, have long been users of conventional AC Induction Motors (ACIM) for operating pumps, compressors, blowers and agitators as common examples. To meet the increasing demand of energy- savings initiatives, the ACIM is rapidly being replaced with Brushless DC motors (BLDC) and Permanent Magnet Synchronous Motors (PMSM). This article presents the reasons why permanent- magnet motors (and their necessary drive and control electronics) are used, and the tradeoffs and challenges in doing so in a cost-effective manner.