Design and Analysis of New Dual-Stator Field Modulation Machines With Multiple Magnetic Excitations

This article proposes new dual-stator field modulation machines with multiple magnetic excitations (MME-DSFMMs), i.e., NdFeB magnet excitation for rotor, ferrite magnet excitation for outer stator, and direct current (dc) excitation for inner stator. The open-slot stator teeth performs the role of modulator to modulate the magnetic field excited by NdFeB magnets. DC field windings with dc in the same direction are used to regulate the magnetic field. The ferrite magnets embedded at the top of outer stator slot are used to suppress the harmonic distortion. Therefore, the proposed machines have the merits of high torque production at low speed, wide speed range, and low torque ripple in full operation range. The configuration, operation principle, and design consideration of the proposed MME-DSFMMs are described. The electromagnetic performances of new topologies with different number of ferrite magnets, including back-electromagnetic force, torque characteristics, and power factor, are analyzed using finite-element analysis to show the merits of the proposed machines.