Hybrid and electric vehicle technology has seen rapid development in recent years. The motor and the generator are at the heart of the vehicle drive and energy system and often utilize expensive rare-earth permanent magnet (PM) material. This paper reviews and addresses the research work that has been carried out to reduce the amount of rare-earth material that is used while maintaining the high efficiency and performance that rare-earth PM machines offer. These new machines can use either less rare-earth PM material, weaker ferrite magnets, or no magnets; and they need to meet the high performance that the more usual interior PM synchronous motor with sintered neodymium-iron-boron magnets provides. These machines can take the form of PM-assisted synchronous reluctance machines, induction machines, switched reluctance machines, wound rotor synchronous machines (claw pole or biaxially excited), double-saliency machines with ac or dc stator current control, or brushless dc multiple-phase reluctance machines.

Energy storage system (ESS) is an essential component of electric vehicles, which largely affects their driving performance and manufacturing cost. A hybrid energy storage system (HESS) composed of rechargeable batteries and ultracapacitors shows a significant potential for maximally exploiting their complementary characteristics. This study focuses on optimal HESS sizing of an example electric vehicle using a multi-objective optimization algorithm, with the overarching goal of reducing the ESS cost while prolonging battery life. To this end, a battery state-of-health (SOH) model is incorporated to quantitatively investigate the impact of component sizing on battery life. The wavelet-transform-based power management algorithm is adopted to realize the power coordination between the batteries and ultracapacitors, in which the ultracapacitors are responsible for handling high-frequency power transients, whereas the batteries deal with average power leveling. The Urban Dynamometer Driving Schedule (UDDS) is used to represent real power demands.