Thermal stability analysis of 6/4 switch reluctance motor using finite element method

This paper studies the thermal stability of a 6/4 switch reluctance machine under nominal operating condition. Transient finite elements method has been used to calculate the machine copper loss and the core loss in magnetic domain. To calculate the copper loss the precise evaluation of current was needed which has been obtained by applying a voltage sources as the input of the electrical circuit of the finite element method. Meanwhile the switching commands have been considered to give a real duty cycle. Moreover the Bertotti loss calculation method has been used to compute the core loss of the machine in the operating condition. The calculated losses in the magnetic domain has been imported to the thermal domain as the heat sources for analyzing the thermal stability of the machine in the operating condition. This study shows that the machine losses are mostly produced by copper loss as the machine does not contain permanent magnet materials to produce high value of flux density in all parts of machine simultaneously. In other words it is shown that most parts of the machine core does not contain high value of magnetic flux as there are just two conducting coils in each moment. Finally it is shown that by a well-designed machine a good thermal stability is feasible for a continuous operating condition.