Variable Magnetic Gear Synchronous Motor for Electric Vehicles

Abstract

Electric vehicles equipped with multi-speed transmissions encounter several technical challenges that can impede their performance and efficiency. A primary concern is the additional weight from components such as clutches and gear sets, which results in a heavier vehicle and a reduced driving range. Furthermore, efficiency losses within the drivetrain, particularly during gear shifts, present issues, as interruptions in power delivery can diminish energy efficiency and affect driving comfort. These mechanical complexities also impose greater demands on the vehicle's control systems. To ensure smooth gear transitions and optimal motor performance, sophisticated algorithms and precise shift schedules are essential. In the absence of advanced control strategies, there is a significant risk of suboptimal performance, increased energy consumption, and compromised dynamic behavior. These challenges underscore the inherent difficulties of integrating multi-speed transmissions into electric vehicles and emphasize the necessity for comprehensive design, simulation, and validation processes. To address these issues, a novel topology for electric vehicles is proposed, which eliminates the need for mechanical gears. This approach utilizes magnetic gears that are both mechanically and magnetically coupled with a permanent magnet synchronous motor, thereby obviating the necessity for mechanical gears. Our proposed motor comprises a permanent magnetic inner rotor, a ferromagnetic rotor, and a permanent magnetic output rotor. The stator's magnetic winding interacts with the input rotor to generate electromagnetic torque, which is then magnetically transferred from the input rotor to the output rotor via ferromagnetic pole-pieces. This configuration facilitates high-speed operation, minimizes noise and vibration, reduces maintenance requirements, enhances reliability, ensures torque transmission, eliminates the need for complex control algorithms, and provides physical separation between the input and output shafts.