I. Introduction
Interior permanent magnet (IPM) synchronous machines are vulnerable to producing significant amounts of current-induced ripple torque if the machine is not carefully designed to prevent it. The torque ripple amplitude can vary significantly depending on the operating conditions. Accordingly, this paper defines the torque ripple at each operating point as the ratio [in per cent] of the peak-to-peak torque variation to the average torque at the operating point of interest.