Magnetization and static torque characterization of a four-phase switched reluctance motor: experimental investigations

The paper presents experimental studies on measurement of magnetization and static torque characteristics of a commercially available 1-hp 4-phase 8/6 switched reluctance motor (SRM). The measured torque profile is also compared with that calculated from flux linkage data using co-energy principles. These experiments used a dSPACE DS1102 digital signal processor (DSP) card to accurately capture voltage and current signal waveforms as well as to precisely monitor rotor angular positions from a 12-bit absolute encoder. "Search coils with DC excitation" technique was used to get magnetization curves, while "balanced beam with hanging mass" method was employed in static torque measurement. The obtained results were acceptably accurate characteristics of the SRM, which will be intensively used in further study on modeling and dynamic simulation. In addition, it is found that torque calculated from the measured flux linkage data had some errors. This is due to the inherent noisy problem of numerical differentiation. Therefore, only measured torque curves will be used in the future control design. There is an attempt to directly find appropriate analytical representations of the torque by curve-fitting the measured characteristics.