An Innovative Variable Magnetic Gear Synchronous Motor Topology for Electric Vehicles

Abstract

The Electric vehicle (EV) performance is critically dependent on the balance between speed and torque, which is managed through the ongoing development of motor technologies and control strategies. However, achieving high rotational speeds presents substantial challenges for conventional motor controllers due to issues such as switching losses, oscillations, and increased thermal loads. Furthermore, the integration of multi-speed transmission systems introduces additional complexity and weight, particularly concerning gear ratio selection and torque management. This study presents an innovative electric motor design for EV applications that eliminates the need for mechanical gearing and specialized controllers. The proposed design incorporates a synchronous permanent magnet input rotor that is magnetically coupled to a three-stage winding output rotor. This configuration facilitates high-speed operation, reduces acoustic noise and vibration, minimizes maintenance requirements, enhances reliability, and provides magnetic isolation between the input and output shafts. The novel integration of magnetic gearing with variable-stage windings enables the motor to sustain high efficiency across a wide speed range. Regardless of the motor type—whether Interior Permanent Magnet, Electrically Excited Synchronous, or C-core Hybrid Switched Reluctance—the proposed design achieves exceptional speed performance through simplified control and precise pole-pair determination. These findings indicate a promising direction for high-speed, gearless electric motor systems designed for next-generation EVs.