Eddy-current machines with permanent magnets and solid rotors

This paper examines the possibility of using permanent magnets (PMs) in the design of solid-rotor eddy-current couplers and brakes. The analysis is based on a magnetostatic finite-element model modified to include an eddy-current distribution calculated in solid parts through an iterative process. Various rotor constructions, with a single layer of either iron, aluminum, or copper or with a composite layer of iron/aluminum or iron/copper, are investigated. The latter offers markedly superior performance, which should, in most cases, justify the extra construction complexity. Magnet construction, in particular the number of poles, is also investigated. The torque characteristic and the design of couplers using PMs seem to differ from their electromagnet-based counterparts, and the paper compares and contrasts the two, in order to identify the applicability of each. The model results compare satisfactorily with the test results obtained from a prototype device.