Electromagnetic Design Characterization of Synchronous Machines with Flux Switching Effect Employing Reluctance Rotors and Stators with PMs and AC Concentrated Coils

This paper introduces an innovative design for a synchronous electric motor that has phase coils and permanent magnets (PM) embedded in the stator. The electric machine contains both concentrated winded phase coils in dedicated slots and spoke-type permanent magnets solely in the stator. The spoke-type magnet arrangement achieves a high flux intensity even with low remanence non-rare earth permanent magnets. As the rotor has no active electromagnetic components, the risk for demagnetization is reduced and advanced cooling applied to the stator can enable high-speed operation. The principle of operation and polarity of the motor are investigated with a unique approach including analytical flux density analysis and piece-wise computational modeling. A design optimization is performed for a 100 kW motor at a speed of 3,000 rpm, which is typical for industrial applications. The conflicting objectives of active material cost and motor losses are considered using both rare-earth and non-rare-earth ferrite PMs in the inner and outer rotor configurations of the proposed motor topology. Discussions on the trade-off between conflicting objectives, a specific EV motor design using ferrites, as well as alternative manufacturing, considering achievable slot fill factor (SFF) and choice of steel are also presented. Furthermore, an open-frame lab prototype (OFLP) of the proposed motor topology is constructed and tested to validate the principle of operation and design optimization approach, with due consideration to manufacturing.