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 digital signal processor-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 a dynamic performance, but also is robust for washing-machine driving applications.