Optimal advance angle for torque maximisation in high-speed, single-pulse operated, switched reluctance machines

It is well reported that Switched Reluctance Machines typically operate in ‘single-pulse mode’ when rotating at high speed. For such operating mode, the control parameters are the duration of the energizing period along with the advance of the turn-on instant, i.e. advance angle. To maximize the output torque, the energizing period is normally kept equal to half of the electric period, i.e. 180° (elec.), whilst the optimal advance angle is evaluated through time consuming finite-element-based optimization algorithms. In this paper, a simple and novel analytical model is proposed that determines the optimal advance angle in a closed-form analytical expression, directly from the machine geometry. Successful validation against accurate finite element models on two Switched Reluctance prototypes is reported.