Comparison of Synchronous Reluctance Motors and Permanent Magnet Synchronous Motors with Direct Liquid Cooling Arrangement

A comparison of Synchronous Reluctance Motors and Permanent Magnet Synchronous Motors with a Direct Liquid Cooling system is given. Both solutions have been analyzed, designed, and optimized considering the same constraints in terms of geometrical volume, current density, and phase voltage, for more equitable comparison. In addition, Direct Liquid Cooling introduces challenges in the selection of the number of conductors per slot and the number of slots because the slot dimensions need to satisfy an aspect ratio close to one and the adoption of a bigger conductor size. The preferred winding configuration is the concentrated one that simplifies the manufacturing process and, therefore, the cost; however, it was not possible to optimize the Synchronous Reluctance Motor with a concentrated winding arrangement achieving a competitive performance. Based on the results it is clear that mostly Permanent Magnet Synchronous Motors can exploit all the advantages of Direct Liquid Cooling, guaranteeing higher performance than Synchronous Reluctance Motors, especially the torque capability in flux weakening operation.