Design of a field-intensified interior permanent magnet synchronous machine for electric vehicle application

[摘要] ENGLISH ABSTRACT: The focus of this thesis is on the optimal design and evaluation of FI-PM machines to be usedwith a MG transmission drive-train for EV application.The machines presented are optimised using a gradient-based optimisation algorithm ofthe VisualDoc software together with FE software and Python scripts. Each machine isoptimised for its own objective function. The focus is to reduce expensive rare earth material.High torque ripple issues of the optimised machines are solved by implementing a relativelynew topology where the rotor poles/barriers are made asymmetric. The asymmetric rotortopology implemented is effective and can be used as an alternative for rotor stack skewing.PM demagnetisation and rotor deformation studies are conducted on the optimum designedmachines to ensure that no PM demagnetisation on the surface of the PMs and criticalrotor deformation occur.The FE performance results of the optimum designed machines are shown and discussed.One of the optimum designed FI-PM machines is manufactured and tested in the laboratory.The FE and measured results of the machine are compared and shows good correlation.The saliency performance of the optimum designed machines are evaluated as it determinesits position sensorless control capability. It is shown that the saliency ratios increaselinearly with load, making it favourable for position sensorless control. It is also shown thatthe asymmetric rotor topologies introduced a larger mutual inductance compared to theirsymmetric counterparts, thus higher cross-coupling is present in these rotors and therefore ahigher saliency shift, which is undesirable. Two case studies are performed in order to improvesaliency performance. The objective of the first case study is to improve the saliency shiftby reducing the flux leakage paths in the rotor. The objective of the second case study is tooptimise a FI-PM machine in order to improve the saliency ratio and -shift. The results ofthe two case studies are compared with the saliency performance of the other machines.

[发布机构] Stellenbosch University