A New Permanent-Magnet Double-Rotor Electric Variable Transmission With Nested-Loop Inductors

Abstract

The magnetic-field modulated brushless double-rotor permanent-magnet machine presents a promising electrification solution, potentially replacing traditional mechanical transmissions such as planetary gear sets in hybrid power systems. However, it faces challenges such as uneven air-gap-length distribution, significant magnetic flux leakage, and limited magnetic field conversion capacity, thereby restricting performance improvement. To overcome these limitations, this paper proposes a new permanent-magnet double-rotor electric variable transmission with nested-loop inductors. The key innovation lies in the introduction of the nested-loop inductor into the permanent magnet double-rotor machine, leveraging electromagnetic induction principles for pole pairs transformation between the permanent magnet and armature magnetic fields. The induced current in the nested-loop inductor generates additional magnetomotive force, significantly enhancing magnetic field conversion capacity and achieving a higher power factor compared to traditional modulating rings. Finite-element-analysis-based simulation results validate the superior performance of the proposed machine.