Design methodology for variable-flux, flux-intensifying interior permanent magnet machines for an electric-vehicle-class inverter rating

This paper presents a design methodology for variable-flux, flux-intensifying interior permanent magnet (VFI-IPM) machines for a 30 kW electric vehicle class inverter rating requirement. Feasible VFI-IPM design considering current in operating range limits of 1 pu is a design objective. Positive I_d vector control with positive reluctance torque, resulted from having L_d > L_q, under loaded conditions and magnetization state changes within 1 pu current (defined at continuous current rating) are primary constraints. Analytical relationships between magnet size, rotor and stator design parameters are used to facilitate a feasible design. Impact of design parameters on machine torque capability and saliency characteristics is evaluated.