Instantaneous Electromagnetic Torque Waveform Calculations for Switched Reluctance Machines Exploiting Vector Analysis

Switched reluctance (SR) machines are magnetically non-linear electromechanical devices and their full and accurate performance prediction—especially of the instantaneous electromagnetic torque waveforms—is not amenable to closed-form analytical solutions. Consequently, the analysis of such machines is usually performed with the aid of computer-based numerical simulations that—even if providing good accuracy—do not offer physical insight into the electromagnetic energy conversion processes taking place inside the machine. For this reason, the SR machine design and analysis are not simple exercises as they require substantial computational resources and extensive prior design expertise. In this article, a methodology for a reasonably accurate prediction of the instantaneous electromagnetic torque waveforms of the SR machines is proposed using a closed-form analytical solution. The suggested approach relies on a simple vector analysis of the flux-linkage map of a non-linear SR machine and as such avoids integration, non-linear curve fitting, or geometrical series summation. The proposed vector-analysis-based methodology offers intuitive physical insight into the electromagnetic energy conversion processes taking place inside the SR machine related to the instantaneous torque generation.