Coupled Magnetic-Thermal Fields Analysis of Water Cooling Flux-Switching Permanent Magnet Motors by an Axially Segmented Model

In permanent magnet flux-switching (PMFS) motors, both magnets and concentrated armature windings are located on the stator, which facilities the accommodation of a water cooling system. It is found that the temperature varies greatly in the PMs, since they are located between the water cooling system and armature windings that carry the heat generated by copper loss. Thus, based on the finite-element analysis, an axially segmented magnetic-thermal coupled-fields model of PMFS motor is proposed, which counts in the variations of flux density, iron loss, and temperature distributions in the axial direction. By dividing the motor into axial segments and neglecting the temperature variation along the axial direction in each segment, this new model enables the electromagnetic and thermal behaviors to be predicted more accurately than 2-D coupled-fields model, meanwhile much faster than a traditional synchronous 3-D coupled-fields model when similar accuracy is obtained. Finally, the results predicted by the new axially segmented model are validated by experimental measurements, confirming the feasibility of the proposed model.