Proposal and Preliminary Experimental Verification of Electrically Reversal Magnetic Pole Type Variable Magnetic Flux PM Motor

Abstract

This paper presents a variable magnetic flux PM motor in which space harmonic power is utilized for the magnetic flux weakening, automatically. The stator has a toroidally-concentrated winding structure, and the torque generation surfaces are composed of three air-gaps, which are single radial-gaps and double axial-gaps. The radial-gap rotor is a consist-magnetized PM rotor, and the axial-gap rotor is a self-excited wound-field rotor. These rotors are coaxially fastened with opposite magnetic pole position. The magnetomotive force of axial-gap rotor can automatically retrieve space harmonic power, which is inevitably generated by a concentrated winding structure. A mechanical design of the prototype is revealed, and the operation principle of the automated-magnetic flux weakening is clarified through the mathematical approach. Then, the operation principle of the electrified reversal magnetic pole is experimentally demonstrated, and the effects of the proposed variable magnetic flux technique are verified using the prototype machine in terms of the adjustable speed drive characteristics and the variable magnetic flux range.