Design, Operation and Performance Evaluation of a Highly Integrated Wireless Excitation System for an Electrically Excited Synchronous Machine

This article presents the design, operation, and performance evaluation of a compact wireless excitation system for an electrically excited synchronous machine. The wireless power transfer system is highly integrated into the hollow shaft of the machine. First, the paper discusses the key design considerations including electrical, magnetic, mechanical, and thermal aspects, followed by a detailed description of the system architecture. Based on a heating and cooling cycle, a lumped-parameter thermal model of the inductive exciter is derived, enabling accurate assessment of the system’s thermal performance limits. The thermal operation limit of the machine is not constrained by the WPT system. Even under worst-case thermal conditions, the WPT system is capable of delivering a continuous output power of up to 2.9 kW. The measured efficiency map demonstrates high performance, with efficiencies exceeding 90 % across nearly the entire operating range and a peak above 95 %. The simulation results show excellent agreement with the experimental measurements, validating the model accuracy.