Optimal advance angle for aided maximum-speed-node design of switched reluctance machines

In the design processes of Switched Reluctance Machines that operate in wide constant power speed ranges, the maximum power available at maximum speed must be evaluated for every machine candidate. This is critical to ensure compliance with the power requirement. Important parameters to include in the design routine are the duration of the energizing period and the advance of the turn-on instant, i.e. advance angle. The latter is highly related to the machine geometry and is usually evaluated through time-consuming finite-element-based iterative methods. In this paper, a simple, yet novel analytical model is proposed to cater for the torque maximising advance angle in a closed-form analytical expression, directly from the machine geometry. The goal is to provide a non-iterative design tool that speeds up the design process. Successful validations against finite element analyses and experimental results on an SR machine prototype are reported. The main outcome of this paper is shown by the improvement in computation time, without any significant loss of accuracy.