Sensorless direct field oriented control of three-phase induction motors based on "sliding mode" for washing machine drive applications

Sensorless direct field oriented (SDFO) control of three-phase induction motors based on "sliding mode" has been studied and applied to domestic washing machine drives. In this paper, three related techniques, sliding mode flux observer, sliding mode speed controller and direct rotor speed estimator are presented for the application of SDFO "sliding mode" in induction motor control system. Specifically, the investigations focus on how improving speed regulation, system robustness and some special technical issues in washing machine drives. The complete control schemes have been developed and implemented in a low cost DSP-based electronic controller. Through a variety of system performance validation tests, it has been proved that the developed SDFO control not only achieves satisfied steady as well as dynamic performance, but also is robust for washing machine driving applications.