Design and analysis of an advanced magnetic variable gear for hybrid electric vehicles

Mechanical gearbox, which plays significant roles in vehicular transmission system, inherently suffers from the drawbacks of wear-and-tear and regular maintenance. Magnetic gears are considered as the preferred gearing device for vehicular transmission system because they have the merits of silent operation, maintenance free and physical isolation. However, the gear ratio of magnetic gear is fixed whereas the gear ratio in vehicular transmission system needs to be can be flexibly varied to fulfill for different driving requirements and road conditions. The purpose of this paper is to propose an advanced magnetic variable gear with six electrically controlled gear ratios for HEVs propulsion system by combining the concept of magnetic gear and the concept of memory machine. The key is to artfully insert double-deck magnetizing/demagnetizing winding into the stationary ring in such a way the aluminum-nickel-cobalt (Alnico) permanent magnet (PM) pieces can be dynamically magnetized or demagnetized, hence achieving the ability of gear-ratio-change . By using finite element analysis, the electromagnetic performances of the proposed magnetic variable gear under different gear ratios are simulated and discussed.