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

A novel computationally efficient finite position set-phase locked loop (FPS-PLL) is proposed in this paper for low-speed sensorless inner permanent magnet synchronous motor (IPMSM) 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 cost function for 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. No parameters need to be tuned and the fast dynamic response is achieved. The rotor speed is extracted by a tracking differentiator-based speed observer (TDSO) without introducing the differentiator. Finally, the effectiveness of proposed scheme is verified by experiment results.