Wireless Power Transfer Based Contactless Excitation of Electrically Excited Synchronous Motor

The present paper describes a contactless excitation system suitable for the control of an electrically excited synchronous motor without the structures of electric brush or slip ring. The proposed contactless excitation system is based on magnetically coupled resonance wireless power transfer. Applying GaN based high-electron mobility transistors, the resonant frequency is set at 1MHz, which avoids the use of iron core and effectively improves the compactness of the system. The resonant network of this strongly coupled system is presented, considering the influence of frequency splitting due to high frequency and minor gap spacing which degrades power output capacity. The physical dimension of circular planar spiral coils is also discussed in this paper. Through simulation and experimental results, the proposed system, which can transmit excitation power under 2mm gap spacing, is shown capable of guaranteeing contactless excitation operation.