Preliminary design of reluctance synchronous machines using simplified magnetic circuit analysis

The performance of a reluctance synchronous machine (RSM) strongly depends on the well-designed geometry of the stator and rotor. Within the intention of a high torque and a high power factor both, the difference and the ratio of the direct-and quadrature inductance must be set to a maximum. In this paper an easy (semi-)analytic design method is used to determine these inductances for a reluctance machine with a standard induction machine stator and a multiple flux-barrier rotor. By varying the rotor and stator dimensions, such as the bore diameter and slot geometry, the effect on the difference and the ratio of the inductances and therefore on the output performance parameters is studied. For the analysis a simplified analytical model, such as a magnetic circuit model of the reluctance synchronous machine is created and solved iteratively. The RSM leakage inductances are determined by using the same analytical equations as used for induction motors. An optimum design for various objective functions like maximum torque, maximum torque per kVA and maximum torque per volume is found, by the means of the analytic model. As a result important conclusions are achieved, regarding the stator and rotor design, respectively.