Novel compact and fast magnetic bearings by saturated main coils and linear auxiliary coils for the gas turbine generator of next generation fast reactors

This paper presents a new design of magnetic bearing structure for application in Nuclear Power Plant (NPP). The proposed design includes so-called saturated coils which is used to generate the bias flux for bearing almost the whole mass of the rotor, and so-called linear auxiliary coil controlled to stabilize the suspension. The saturated coil is considered as an special electromagnet which is controlled to operate in the region of magnetic saturation in order to minimize the bias current as well as to enhance the magnetic flux density. This strategy will result in a very compact size of magnetic bearing as well as increasing the speed of the response of the current controller. The novel structure is expected to be applied to design very high power gas turbine generator of next generation of fast reactor in which the mass of rotor can reach 50 tons. The total power of the NPP can reach 2,000 MW. Moreover, the issue of arc occurrence between coils is also discussed and two solutions are proposed.