A Novel Torque-Coupled Axial-Flux Permanent Magnet Motor with Magnetic Coupler for Flux Weakening

This paper proposes a torque-coupled axial-flux permanent magnet (AFPM) motor with a wide speed operating range. The motor system incorporates an innovative and adaptive mechanical flux weakening method comprising a single-stator dual-rotor type AFPM and a magnetic coupler with a rigid stopper. The two components are concentrically integrated to maximize radial space utilization, enabling the torque generated by both rotors to collaboratively act on the load side through the magnetic coupler. As the load torque varies, the torque of both rotors is also regulated. This enables the automatic adjustment of the angular displacement between the two rotors through the magnetic coupler, thereby changing the combined electromotive force (EMF) to achieve a wide speed range flux weakening operation. In addition, the implementation for calculating the flux weakening degree during constant power operation is presented. Finally, the effectiveness and feasibility of the design are validated through three-dimensional finite element simulations.