Linear analysis of two-, three- and four-phase switched reluctance machines with variable pitched winding configurations

The results from a generalised linear analysis of switched reluctance machines with various winding and phase configurations are presented. The generalised analysis is used to analyse ten 4/2, 6/4, and 8/6 pole machines with various stator coil pitches and excitation patterns. Twenty-six combinations are analysed with a fixed frame size. The optimum stator and rotor pole arc combinations for maximum torque per unit current production are determined. An iterative procedure is then used to determine the optimum rotor diameter, given the frame size, permissible total copper loss and flux density. The restrictions on copper loss and flux density provide a reasonable comparison between the average torque developed by each machine. The technique is linear, therefore it does not incorporate saturation and pole flux fringing effects. The analysis highlights that the optimised machine geometry is a function of the current excitation pattern and coil pitch employed.