Design and test of capacitive power transfer coupling for wound field synchronous machines

This paper deals with the design and test of a contactless capacitive power converter operating at a frequency of 1 MHz, intended to supply the excitation winding of an 80 kW wound rotor synchronous machine. The methodology integrates the electromagnetic design of the rotor and its impact on the different parameters of the converter. To verify the validity of the concept, a first prototype was built by using surface-mounted capacitors grounded on the structure of a 1 MHz Class E resonant power converter. Then, a more representative capacitive contactless coupler was designed and implemented. Comparisons between simulation and experimental results have shown the limits of the proposed contactless power transmission. Special attention was paid on losses and efficiency which are crucial for this application.