Self-Excited Diode Rectifying Wound-Field Synchronous Motor Utilizing Space Harmonics and Flux-Intensifying with Carrier Harmonics

This paper describes a novel self-excitation technique in which space harmonics and carrier harmonic is effectively utilized for the field magnetization instead of permanent magnets. The unique point of this technique are the following points. The second-order space harmonic that is structurally unavoidably generated in the motor with concentrated winding stator is utilized for self-excitation by inductive coupling. Secondary, the carrier harmonics inevitably generated in motor controlled by inverter are utilized for flux-intensifying by inductive resonance coupling. After explaining the proposed new self-excitation principle, then, the prediction of driving characteristics by electromagnetic field analysis (FEA) is shown. In particular, the effect of value of the carrier frequency to be magnetically resonant coupled and the torque improvement effect by the flux-intensified electromagnet are clarified. Consequently, it has been clarified that the proposed new permanent- magnet free motor can improve the torque density in the low-speed area because the carrier harmonic can generates the large electromangetomotive force in rotor winding by inductive resonance coupling.