Torque Observer Based Sensorless Starting Control of SPMSM for Wankel Rotary Engine Drives Using I‐F and EKF

ABSTRACT The Wankel rotary engine (WRE), renowned for its high power density and compact structure, faces challenges in starting performance due to periodic load torque fluctuations and sensor reliability issues in harsh operating environments. To address these limitations, this study proposes an integrated control strategy combining sensorless control and an improved sliding mode observer (SMO) with an optimized reaching law design. The sensorless control integrates the extended Kalman filter (EKF) for rotor position estimation and I‐F control to achieve smooth start‐up of the surface‐mounted permanent magnet synchronous motor (SPMSM) under zero and low‐speed conditions, eliminating dependence on physical position sensors. A sliding mode observer with an optimized reaching law is designed to estimate periodic load torque disturbances, enabling real‐time feedforward compensation. Simulation results demonstrate that the proposed strategy ensures a smooth starting and seamless transition from standstill to target speed while reducing speed overshoot by 7.6% and suppressing steady‐state speed fluctuations by 76.5% compared to uncompensated systems. These advancements significantly enhance the SPMSM‐driven WRE's dynamic response accuracy, steady‐state stability, and operational robustness under harsh conditions. The proposed framework provides a scalable solution for high‐performance WRE control, particularly suited for compact, weight‐sensitive systems requiring high power density and reliability.