Exploitation of the renewable energy is expected one of the most effective expedient to reduce of green house gas emissions, principally CO 2 . In this context, small-sized hydraulic power generation is considered one effective method because of its potential energy amount. However, mechanical bearing which support the rotor shaft causes rotational loss and durability limitation. For the purpose of upgrade performance of hydraulic generator, permanent magnet hybrid type magnetic bearing is proposed in this study. Stator is designed by finite element method magnetic field analysis in order to obtain stronger bearing force with same size stator diameter. In addition, simple experimental setup is manufactured with the object of measuring bearing force of proposed magnetic bearing. Moreover, in order to predict dynamic performance of the rotor, simulation was carried out by using measured bearing force stiffness and permanent magnet negative spring constant. Simulation result show high response performances.Index Terms-Magnetic bearing, Magnetic field analysis, Bearing force characteristics.
In order to reduce greenhouse gas emissions, the generation of renewable energy is required. Therefore, this paper focused on a small-sized hydraulic generator, since small scale hydropower has a large potential for power generation. Standard mechanical bearings are installed in conventional small-sized hydraulic generators to support the rotating shaft. However, mechanical ball bearings cause rotational loss, noise and limitation of device durability. In order to upgrade the performance of a hydraulic generator, a new type of permanent magnet hybrid type magnetic bearing is proposed in this study. The stator is designed by finite element method magnetic field analysis. According to the analytical result, by making the root of stator salient pole wider and eliminating magnetic saturation, stronger bearing power was obtained. The analytical attractive force and negative spring force characteristics were then verified under static operation conditions with a simple experimental setup. Moreover, in order to confirm dynamic performance in the time domain, the impulse response was measured with the result showing good performance. In addition, by using the measured coefficient of attractive force and negative spring force, a numerical simulation was carried out to check the dynamic performance in the frequency domain and compared with an experimental result. The result of the frequency response showed good control performance in frequency domain.
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