Position estimation scheme robust for rapid change of inductances in synchronous reluctance motors

Generally, It is supposed that there is the difference of 20% at least between the inductance at a light load and the one at the ratings load. Position sensorless control methods robust for the change of the inductance have been proposed by other researchers, but they have the demerits that the system configuration and/or the calculation scheme is complex and that it is difficult to cope with a rapid change of the inductance. Although the authors are studying a position sensorless control in all speed ranges in synchronous reluctance motors, first the method which can drive in steady in more than 10% of rating speed has been investigated. The method is characterized by the calculation scheme for the position estimation and the use of the inductance table for stable speed control. In this paper, the merits of the proposal position calculation scheme and using the inductance table are shown theoretically and through experiments.