The structure optimization of novel harmonic current excited brushless synchronous machines based on open winding pattern

In an open-winding machine, the three-phase stator currents can be controlled to contain the third harmonic current component, which could generate a third harmonic vibration pulse magnetic field. The brushless harmonic excitation principle is realized by utilizing this field. On the role of producing rotor harmonic winding induced back-EMF, it hopes that the third harmonic vibration pulse magnetic field plays a maximum role, meanwhile, the influence of high harmonic magnetic field and tooth harmonic magnetic field should be minimum. This paper had carried on the theoretical analysis about the influence factors of rotor winding induced back-EMF and concluded that the 4 poles, 18 slots, pitch of 4 structure is best suited for this principle. Finally, the finite element simulation analysis was performed and the simulation results were consistent with theoretical analysis, which validated the correctness of the theory.