Comparative Analysis and Design of Double-Rotor Stator-Permanent-Magnet Motors with Magnetic-Differential Application for Electric Vehicles

Abstract

In order to get rid of the bulky and lossy differential gears and to enhance the system robustness, the magnetic differential (MagD) system is proposed after the mechanical differential (MechD) and electronic differential (ElecD) systems. The MagD system is mainly composed of the double-rotor (DR) stator-permanent-magnet (PM) motor with a new set of winding whose magnetic field reversely interacts with the PM field in two rotors. As a result, the compactness and reliability of the system are improved. This paper quantitatively compares and analyzes the three major types of stator-PM motors applied in the MagD system, which can give an essential guideline on the choice of motor types in various situations. All kinds of motors are optimized in the same exercise, and their performances are thoroughly evaluated and compared by using three-dimensional finite element analysis. Finally, the motor with the best overall performance is prototyped, and the MagD system is set up for experimental verification of the optimized flux-switching PM motor.