Modelling and design optimisation of permanent magnet machines for electric vehicle traction applications

• Main Author: Chen, Liang
• Other Authors: Wang, Jiabin
• Published: University of Sheffield 2016
• Subjects: 629.22
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.713268

While the fuel resource scarcity and the environment crisis are becoming two of the major problems for the human society in the new century, in the context that the on-road transport is the largest energy-consuming society sector, electrical vehicles (EVs) serving resource-sustainable environmentally-clean transport attract increasing attention. Permanent magnet (PM) traction machines with high torque and power densities, and high energy efficiency gain great interest from the engineer and industry communities. Jointly with the chances, fresh challenges are brought by EVs to PM machine designers. In response to the vehicles' call for high speed, mighty acceleration, long range, safe and robust system, the engineers need to develop a powerful design platform that allows for multi-physic evaluations of machine designs over a large torque-speed range, especially for energy efficiency, PM health, and thermal-withstanding ability. More importantly, these evaluations must be against driving cycles rather than on a single rated operation point in catering to various real-world driving conditions. The complex and enormous computation efforts required necessitate new, effective and feasible design techniques. In this work a set of modelling techniques for PM machines are developed, in order to establish a computationally-efficient yet accurate design and optimisation method for EV traction PM machines. Through the method, comprehensive machine multi-physics assessments against driving cycles are enabled; electro-thermally coupled evaluation is achieved; 3-dimensional eddy-current loss of PMs are accurately monitored in the context of PM protection; lastly with the techniques integrated together, a fast and effective optimisation method for EV traction PM machines is acquired. To exploit the benefits of the proposed method, a design, optimisation and manufacture process of PM machines for a light-duty EV distributed traction system is formatted, which includes a quantity assessment of machine topologies, investigation of driving cycle influence on designs, optimisation of the selected 18-slot 8-pole interior PM machine against a series of EV machine design criteria, the subsequent prototype experiments, and optimisation of combinations and power split ratios of PM machines for the distributed traction system. Through the design process for the EV traction system and experiments, the effectiveness, computational efficiency, and accuracy of the proposed designing methods are exhibited and validated.