Torque Density and Efficiency Improvement of a Switched Reluctance Motor via low-cost Permanent Magnets

A Switched Reluctance Motor (SRM) is often characterized with structural simplicity and low cost. However, its torque density and efficiency is generally lower than any same size AC machine. In this research, performance improvement in the SRM has been investigated under the presence of low-cost permanent magnets (PMs). The Permanent Magnet Switched Reluctance Motor (PM-SRM) is formed by burying PMs on stator yoke. A non-rare earth type magnet, Alnico, has been employed for this purpose. Alnico magnets in AC machines is limited because of low coercivity against reverse magnetic field. However, this is not an important issue for PM-SRM driven by an Asymmetric Half Bridge Converter. The analysis results of PM-SRM demonstrate that a significant increase in efficiency, torque density as well as in power factor can be obtained without losing much from the low-cost feature.