Document Type

Conference Proceeding



Publication Date



Institute of Electrical and Electronics Engineers (IEEE)

Source Publication

2016 IEEE Energy Conversion Congress and Exposition (ECCE)

Source ISSN



This paper presents the performance trade-offs in the design optimization of spoke-type permanent magnet (PM) motors for high speed and very high torque density traction motors. An example 18-slot 16-pole machine for a direct drive Formula E race car over the Le Mans driving cycle is considered. Both low speed and extended speed/field-weakening operations are evaluated using high fidelity finite element (FE) simulations, to simultaneously increase the torque density and decrease the power losses over the high energy-throughput-zones of the machine torque-speed plane. The results of the design optimization process yielding 3,400 design candidates are utilized to quantify the performance trade-offs for increasing the power density in spoke-type PM motors. These trade-offs include the impacts on other performance metrics such as power losses, PM demagnetization, and torque ripple. The analysis is supplemented by multi-physics simulation of three counterpart optimized designs, and successful experimental verification of a prototype of one of those three designs which represents a record high power density motor in traction applications.


Accepted version. Published as part of the proceedings of the 2016 IEEE Energy Conversion Congress and Exposition (ECCE). DOI. © Institute of Electrical and Electronics Engineers (IEEE). Used with permission.