Implementation issues and performance evaluation of sinusoidal, surface-mounted PM machine drives with Hall-effect position sensors and a vector-tracking observer

This paper presents the implementation and evaluation of a high-resolution position estimation system for sinusoidal, surface phase modulation machines based on Hall-effect sensors and a vector-tracking observer. First, the tuning of the observer is presented and a speed-dependent gain scheduling strategy is proposed. Then various harmonic decoupling strategies are investigated to improve the performance of the observer, particularly at low speeds. Stability analysis is performed leading to the definition of local stability limits, within which the actual position is tracked with bounded estimation error. Both simulation and experimental testing illustrate the performance and limitations of the proposed observer topology and of the drive when this observer is used for state feedback.