Identification of synchronous reluctance motor parameters

The detection of the neutral point voltage of three-phase synchronous reluctance motors is useful for obtaining information on the operating conditions of the motor and also on the Fourier coefficients of the air gap permeance. It is known that these parameters are crucial for the accurate evaluation of the motor’s main quantities. Modelling the motor so as to take into account of the harmonics of both magneto-motive force and air gap permeance, the homopolar component of the induced voltages is obtained. It is shown that amplitude and phase of each harmonic of the homopolar voltage can be expressed as a function of two Fourier coefficients of air gap permeance, which suggests using a procedure for on-line calculating these coefficients. The parameters of a small prototype of reluctance motor have identified using a seven bit digitizing oscilloscope connected to a digital computer in which a DFT algorithm has been implemented for evaluating amplitude and phase of the harmonics of neutral point voltage.