科研之友
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摘要
Ultrahigh-speed electrical drive systems enable small-scale electrically driven turbo-compressors for industrial applications, such as fuel cells and heat pumps, due to their compact size, high power density, and high efficiency, in combination with oil-free operation. However, a major obstacle in the industrial implementation of such turbo-machinery is the lack of bearing technologies suited for high rotational speeds. Promising bearing candidates for long lifetime at high rotational speeds are contactless bearing types, such as gas bearings or activemagnetic bearings. Gas bearings allow for compact system integration with high load capacity and stiffness; but their application at high rotational speeds is limited by their poor dynamic stability. Active magnetic bearings facilitate a precise control of the rotor dynamics; however, at the price of a substantially increased installation and system complexity. Aiming to combine the advantages of these two bearing technologies, a hybrid bearing approach is proposed using a self-acting gas bearing for providing the main load capacity in combination with a small-sized active magnetic damper to achieve stable operation at high operational speeds. In order not to impair the compactness of the resulting drive system, dedicated displacement sensors are avoided by employing an eddy-current-based self-sensing rotor displacement measurement method using high-frequency signal injection. A previously proposed eddy-current-based self-sensing method is refined and implemented; measurement results are presented for a prototype machine proving the feasibility of the proposed hybrid bearing approach.
- 出版日期2017-4
