Compact and low cost magnetic bearing with saturated coils for gas turbine generators

Abstract

A novel magnetic bearing system for gas turbine generators of next generation nuclear power plant is pro-posed. This system newly adopts saturated coils for generating main bias force and small size linear auxiliary coils for stabilizing the suspension. The saturated coils operate in the region of magnetic saturation in order to maximize the magnetic flux density and reduce the bias current. This results in compact size of core, significant reduction of copper loss; hence, a low cost and high efficiency magnetic bearing is achieved. The proposed sys-tem is under development for the goal of 50 t rotor mass and 300MWe power.A small prototype of the proposed magnetic bearing is being built to verify the feasibility of the saturated coils in magnetic bearing and to evaluate the advantage of the proposed one compared to ordinary active magnetic bearing. The prototype was designed to levitate a weight of 1 kg and operate with maximum speed of 3,000 rounds per minute (rpm). The design and the experimental results are also shown in the paper.