Design of a Synchronous Reluctance Motor Assisted with Permanent Magnets for Pump Applications

Sammanfattning: This Master thesis focuses on the design of a high efficiency Permanent-Magnet-Assisted Synchronous Reluctance Motor (PMASynRM) intended for pump applications. The new motor is designed to replace an existing Induction Motor (IM) in a pump product. The basic principles of SynRM, and PMASynRM Motors and a good analytical model were introduced. Due to the complexity and high non-linearity of this specific electrical machine, Finite Element Method (FEM) and an analytical model were combined. First, a parameter sensitivity analysis was carried out with the software SPEED. However, SPEED does not give appropriate results for the sensitivity analysis of the distance from the shaft to the first barrier, and in this case, the FEM software FLUX was used instead. Using FEM as well, the risk of demagnetization of the magnets was controlled for the nominal current and for overload conditions. Furthermore, some conclusions were drawn in terms of the losses, and efficiency for the selected design. The design fulfills the required efficiency placing either ferrite or neodymium iron bore magnets in the rotor barriers. However, if ferrite magnets are employed, the maximum current should be controlled to avoid demagnetization. Finally, a ferrite PMASynRM prototype was built and tested in the lab. The simulation results as well as the measurement of other possible technologies including IM and Line Start Permanent Magnets (LSPM) machine were compared with the measurements of the prototype in terms of efficiency, power factor and cost. It is concluded that the designed PMASynRM is a good alternative as it surpassed the required efficiency and the results from the simulation were close to the test measurements.