Robust Position Sensorless Control Against Inductance Variations of Synchronous Reluctance Motors in Low-Speed Region Using High-frequency Current Control

Synchronous reluctance motors (SynRMs) have attracted attention because they have no magnets. The position sensorless control of SynRMs at low speeds is desired, and several methods have been proposed. A new position sensorless control method for SynRMs in a very-low-speed region has been proposed by the authors. It involves superimposing a high-frequency current with a small constant amplitude, using a high-frequency current control system. This paper shows that robust position sensorless control against inductance variations can be realized using this proposed method. Experiments showed that the proposed method is very useful even in a very-low-speed region.