Critical review of direct-drive electrical machine systems for electric and hybrid electric vehicles

• Main Authors: Cai, Shun, Kirtley, James L. Jr., Lee, Christopher Ho Tin
• Other Authors: School of Electrical and Electronic Engineering
• Format: Article
• Language: English
• Published: 2023
• Subjects: Engineering::Electrical and electronic engineering; Direct-Drive; Electric Vehicle
• Online Access: https://hdl.handle.net/10356/166305
• Institution: Nanyang Technological University

With ever-increasing concern of fossil fuel storage and environmental pollution, transportation electrification has recently attracted extensive attention. In conventional propulsion systems, the engine is connected to the wheel through a clutch, reduction gearbox, and mechanical differential. The mechanical transmission inevitably results in power loss, noise, vibration, and additional maintenance. With elimination of the gearbox and transmission component, the direct-drive technique exhibits significant advantages of higher systematic efficiency, more flexible wheel control, and better passenger comfort. This paper aims to provide an overview of automobile direct-drive techniques and recent electrical machine developments for direct-drive propulsion systems. Benefits and limitations of various direct-drive machines are summarized and compared with typical industrial products. Finally, the opportunities, challenges, and future development trends are discussed in related to the research 'hot spots'.