Design and Analysis of Brushless Wound Field Synchronous Machine With Electro-Magnetic Coupling Resonators

The increasing price of rare earth permanent magnet has refocused the attentions to substitute Permanent Magnet Synchronous Machine (PMSM) with Wound Field Synchronous Machine (WFSM), which needs an excitation device to deliver current to the field winding. This paper presents one solution transferring the excitation power into the winding on the rotor of WFSM via electro-magnetic coupling resonance. Analysis, design, and prototype construction of the system are presented. Experiments demonstrate the system can transfer 200W to the field winding of a 2kW WFSM and the overall excitation device efficiency can reach 85%. The proposed technique has unique advantages over other wireless power transfer excitation technologies.