Sensorless IPMSM Control Under Parametric Uncertainty for Washing Machine Drives

Reliable rotor position estimation is a key enabler of efficient low-speed control in sensorless Interior Permanent Magnet Synchronous Motor (IPMSM) drives used in horizontal-axis washing machines. Performance at low speeds is challenged by variable loads and temperature-induced changes in stator resistance and magnetic saturation. This paper presents a Proportional-Integral (PI) observer based on an Extended Flux (EF) model, designed to handle variations in d-q axis inductances and stator resistance during extended wash cycles and dynamic loading. Implemented on a TMS320F28335 motor control kit and validated with a 900 W IPMSM, the method achieves accurate rotor position estimation, stable torque control, and reliable operation at 87 rpm under full load. It also maintains transient stability at higher speeds. The EF model's simplicity supports deployment on low-cost microcontrollers, making it ideal for household appliances. The proposed approach improves washing performance, reduces energy consumption, and enhances long-term control stability under real-world conditions.