High Speed Permanent Magnet Assisted Synchronous Reluctance Machines - Part II: Performance Boundaries

The insertion of permanent magnets (PMs) within the rotor slots of Synchronous Reluctance Machines (SyRM) is the most common design strategy used to increase significantly their performance. In this paper it is shown how a permanent magnet assisted synchronous reluctance machine (PMaSyRM) can be optimized to satisfy all the electromagnetic and structural constraints arising as the maximum operating speed increases. This is done considering a variety PMs material. This work, the second of two companion papers, briefly recalls the novel systematic design approach proposed in Part I, and then describes the characteristics of the optimal machines achieved considering a maximum speed ranging from 1 to 140 krpm with and without the assistance of ferrite and neodymium based PMs. The reasons behind the performance deterioration as the speed increases are all investigated along with the geometrical variations of the optimal designs. The selection of the design solution to be manufactured is justified as well as the final structural and electromagnetic refinement stages leading to the prototype. All the reported considerations are experimentally validated testing an 8.5 kW at 80 krpm PMaSyRM, comparing the measured and expected performance in terms of torque and internal power factor.