Energy efficiency of electric machines used in electric vehicles

Abstract

This thesis investigates the efficiency performance of two types of synchronous reluctance machines Permanent Magnet-Assisted Synchronous Reluctance Machine (PMSynRM) and non-magnet Synchronous Reluctance Machine (SynRM) in the context of electric vehicle applications. The main objective is to model their energy conversion behavior using efficiency maps and simulate their performance under various standard driving cycles. The study is divided into two main parts. In the first part, finite element analysis (FEA) and Syre software are used to generate detailed loss and efficiency maps for both machines based on geometry and material data. These maps provide insight into how torque, speed, and loss mechanisms affect overall performance. In the second part, the generated efficiency maps are implemented into a Simulink-based vehicle model. Standard driving cycles including UDDS, FTP-75, NEDC, and WLTP are applied to evaluate the dynamic performance of each machine in realistic driving conditions. The energy consumption, regenerative braking, and conversion efficiency are analyzed and compared. The results show that the PMSynRM outperforms the SynRM in terms of energy efficiency and mechanical output across all drive cycles. The presence of permanent magnets contributes to reduced copper losses and smoother torque generation. While the SynRM operates without rare earth materials, it exhibits higher I²R losses and lower average efficiency. This work provides a quantitative basis for selecting machine types based on efficiency maps and realistic driving demands. Future work will focus on detailed loss mechanism modeling within the Simulink environment to improve accuracy and system-level optimization.

Date of Award	2025
Original language	English
Supervisor	Rastko Zivanovic (Supervisor)