Magnetic levitation control of high-temperature superconducting floating coils using image-data processing

点击翻译按钮获取中文摘要

A new feedback control scheme using image-data processing is proposed for magnetic levitation of superconducting floating coils such as used in the Mini-RT project. In the conventional system of our previous studies, the position of a floating coil was measured using laser sensors, and the current of the levitating coil was controlled with an analog PID circuit. The new system has incorporated a digital control program with personal computers(PC). A graphical measurement-and-control software, LabVIEW is used in the system and a sufficient feedback-control capability was confirmed by levitating permanent magnets. A miniature superconducting floating coil was fabricated using silver-sheathed Bi-2223 high-temperature superconducting cables and this could also be successfully levitated. In addition to the main PC that directly drives the PID control program, a local PC and a remote PC are also used. The real-time image of the floating coil is taken by a local PC with a CCD camera. A remote … More PC can obtain this image and can also change the parameters necessary for the PID control. The system was connected to the fast network, Super-SINET, and the magnetic levitation experiment was conducted with a remote control from the Univ. of Tokyo. As described above, the present system has already attained sufficiently sophisticated capabilities, however, the magnetic levitation with a direct image-data processing has not yet been completed. We have examined some problems related with this control scheme, such as that the characteristic time constant of control becomes much longer than that with laser sensors due to the slow frame rate of a camera. However, it was confirmed by an experiment that the characteristic time constant of motion of a superconducting coil is effectively long due to the conservation of magnetic flux, and thus, the levitation control using image data can be applied. On the other hand, the conservation of magnetic flux in superconducting coils gives another interesting finding of self-stabilized magnetic levitation, which is supposed to be used in some engineering applications. Less