Overview of Energy-Efficient Magnetic Gears in Electric and Hybrid Vehicles

Magnetic gears offer an energy-efficient alternative to conventional mechanical gears through magnetic fields rather than physical contact. A non-contact operation eliminates frictional losses, mitigates wear, and reduces vibration, noise and maintenance requirements. In recent years, the development of magnetic gear technologies has accelerated, driven by advances in materials, innovative gear topologies, and emerging applications. This paper presents a comprehensive review of magnetic gear technologies with particular emphasis on their applications in battery electric vehicles and hybrid electric vehicles. First, the development of magnetic gears is reviewed from early converted magnetic analogues of mechanical gears to high-performance field-modulated variable gear designs. The review subsequently examines the use of magnetic gears in electric vehicle applications, including magnetic geared in-wheel motors, traction modules, and magnetic gears in hybrid electric vehicles, such as magnetic variable gears for hybrid vehicle applications, magnetic geared electric variable transmissions and power-splitting devices. The review also discusses novel and less-established MG applications before examining the challenges limiting their widespread adoption in EV and HEV drivetrains.