Impact of modifying the stator tooth tip on electromagnetic torque production for an 8/6 switched reluctance machine

Switched reluctance machines (SRM) offer unique operational characteristics when compared to other electrical machines. For instance, SRMs tend to have higher fault tolerance when compared to the industrial standard, pulse width modulation driven induction machines, due to their phase winding isolation. Furthermore, they may remain in a locked rotor position safely without concern of faulting and have higher speeds than many other electrical machines. SRM still only have niche applications due to requiring higher currents, producing more acoustic noise and torque ripple, and needing for more advanced controls for effective operation. Such constraints contribute to the reduced commercial and industrial popularity when compared to other electrical machines and have limited the full potential of SRM from being exploited. This paper describes the impact on the electromagnetic torque production of an 8/6 switched reluctance machine when increasing and decreasing the stator pole arc at the tip. Such a technique of increasing the stator pole arc can provide torque shaping, furthermore, there is a significant improvement in the torque ripple of the machine. We focus on the qualitative analysis of the results from magnetic equivalent circuit of the SRM with modification of stator pole arc without pole tapering. Finite element analysis (FEA) with commercially available software is utilized to support our results.