Integrated Modular Motor Drives Based on Multiphase Axial-flux PM Machines with Fractional-slot Concentrated Windings

The integrated motor drive (IMD) concept with possible modularization has attracted much attention in a broad spectrum of applications ranging from low-power general-purpose industrial drives to high-power electric propulsion. This paper presents the feasibility study and performance evaluation of using common axial-flux permanent-magnet (AFPM) machines with fractional-slot concentrated windings in IMDs, with the same diameter and a minimum increase in its axial length. Different winding configurations are compared in terms of the torque/power capability and fault tolerance without changing the winding current rating. The possibility of further torque improvement is discussed from the perspective of making full use of the air-gap field harmonics produced by PMs. An AFPM machine available in the lab has been dissembled and used to build the proof-of-concept design, to show the feasibility of the proposed design and benefits of the IMD.