With ever-increasing concerns on our environment, there is a fast growing interest in electric vehicles (EVs) and hybrid EVs (HEVs) from automakers, governments, and customers. As electric drives are the core of both EVs and HEVs, it is a pressing need for researchers to develop advanced electric-drive systems. In this paper, an overview of permanent-magnet (PM) brushless (BL) drives for EVs and HEVs is presented, with emphasis on machine topologies, drive operations, and control strategies. Then, three major research directions of the PM BL drive systems are elaborated, namely, the magnetic-geared outer-rotor PM BL drive system, the PM BL integrated starter-generator system, and the PM BL electric variable-transmission system.
Index Terms-Electric variable transmission (EVT
), electric vehicle (EV), hybrid EV (HEV), integrated starter generator (ISG), magnetic gear, permanent-magnet (PM) brushless (BL) drives. I. INTRODUCTION V EHICLES equipped with internal combustion engine (ICE) have been in existence for over a hundred years. Although ICE vehicles (ICEVs) are being improved by modern automotive electronics technology, they need a major change to significantly improve the fuel economy and reduce the emissions. Electric vehicles (EVs) and hybrid EVs (HEVs) have been identified to be the most viable solutions to fundamentally solve the problems associated with ICEVs [1]-[3]. Electric drives are the core technology for EVs and HEVs. The basic characteristics of an electric drive for EVs are the following [4]-[6]:
- high torque density and power density; 2) very wide speed range, covering low-speed crawling and high-speed cruising; 3) high efficiency over wide torque and speed ranges; 4) wide constant-power operating capability; 5) high torque capability for electric launch and hill climbing; 6) high intermittent overload capability for overtaking; 7) high reliability and robustness for vehicular environment; Manuscript