A Novel Computationally Efficient Finite Position Set-Phase Locked Loop for Low-Speed Sensorless IPMSM Control

This letter proposes a novel computationally efficient finite position set-phase locked loop (FPS-PLL) for low-speed sensorless interior permanent magnet synchronous motor control. A novel equivalent position error is designed based on the complex operation of current responses, enabling the derivation of an improved Newton iteration formula. The iteration formula is convergent in the whole computational domain so that the iterative operations about the cost function for the appropriate iterative initial value can be avoided. Only two iterations are required to obtain the finest rotor position, which is less than existing FPS-PLL schemes. The parameter tuning is avoided in the iterative search process for rotor position, and the fast dynamic response is achieved. Moreover, a tracking differentiator-based speed observer is designed to extract the rotor speed without introducing the differentiator. Finally, the effectiveness of the proposed scheme is verified by experimental results.