Directly Cooled Windings in Switched Reluctance Machines

Compared to conventional electric machines, Switched Reluctance Machines (SRMs) are recommended to work in the saturation region to maximize the output energy. This is done by increasing the stator current to a certain limit that is usually identified by the maximal winding temperature. One method to cool the electric machine of concentrated windings is to insert cooling tubes between the windings in which a liquid is flowing. This paper investigates the influence of inserting cooling tubes between the windings of SRM on the losses and hence the resulting temperature distribution. A stator setup without rotor is employed. It is found that, in general, the losses in the cooling tubes are not significant, particularly for materials with a low electrical conductivity and a small thickness. However, the thermal analysis shows that a compromise between the thermal and the electrical conductivities for the tube material is preferred. Some experimental validations are obtained on a stator setup of 6 teeth.