Wireless Power Transmission Excitation Systems for Electrically Excited Motors: Comparison of Magnetic Coupler Topologies

Brushless excitation technology based on wireless power transmission can replace the brush and slip ring in the electrically excited synchronous machine (EESM), and further exert the advantages of EESM with strong speed expansion capability, low cost, and high efficiency in high-speed areas. The rotary magnetic coupler is the core component for transmitting power in wireless excitation devices. Based on the characteristic of magnetic field distribution and the characteristic of the rotating part of the receiver side, this paper divides the magnetic coupler into four types: axial rotating-core type, axial rotating-winding type, radial rotating-core type, and radial rotating-winding type. On this basis, different magnetic couplers are compared and analyzed in terms of output power, rotational centrifugal force, temperature, cost, and installation portability, and then the application areas of different couplers are given.