| Magnetic refrigeration is a rising refrigeration technology. Due to characteristics of environment and safety, it becomes a hotspot for study in recent years. Now, the magnetic refrigerator technology is still undeveloped, and the superconducting magnet system and permanent magnet system are mainstream magnet systems used. In this paper, a novel repeating pulsed magnetic system has been developed for magnetic refrigerator. Compared with the existing superconducting magnet or permanent magnet system, repeating pulsed magnet can give consideration to high magnetic field and low cost, while no moving component between the magnet and the magnetic refrigeration materials is needed.The repeating pulsed magnetic system itself is a novel branch of pulsed high magnetic field, and has high repeating frequency and good potential. As it is more complex than the standard pulsed magnetic field system, its research is quite few and the pulse widths are less than10ms. In order to meet the need of magnetic refrigeration, the proposed repeating pulsed magnetic system has a pulse width of193ms, which is much longer than the existing system.In the context of magnetic refrigeration, all about design, implementation, test and its application of the proposed repeating pulsed magnetic system are presented in the dissertation, in the respects of power supply design, magnet design, control measurement design and the experiment.In the respect of power supply design, a specially designed topology for repeating pulsed magnetic system has been developed-no crowbar or choke coil used, which is quite different from the existing repeating pulsed magnetic system. With this topology, the utilization of energy is maximized. An AC power capacitor is used as main capacitor bank and bidirectional charge and discharge is implemented. After design, simulation and type selection, a1.5kV/45kJ pulsed power supply system with75capacitor bank, a charger, isolate branch, thyristors and related elements has been developed.In the respect of magnet design, a novel repeating pulsed magnet with large inductance and rapid cooling performance has been developed after absorbing related magnet design methods from America, Germany, France, England and Japan. In design, the peak magnetic field, cooling channel structure and magnetic field uniform are studied especially and ideal parameters of the magnet are obtained. Through attempt, the proposed pulsed magnet with large inductance and rapid cooling performance has been finally developed. It has an inductance of87mH and a77K resistance of0.4Ω, which meets the design requirements well.In the respect of control and measurement system, a control system with Labview software has been developed to control the power supply, magnet and electrical motor, including developing a Labview control system for the power supply and magnet, developing a PLC platform to control the electrical motor and electric cylinder, matching the PLC control system with the Labview control system and the measurement system. Communication process is presented in detail in the end.Finally, an experiment about the designed repeating pulsed magnetic system is successfully carried out. In the tests, essential shielding processes are performed for signal transmission in strong electromagnetic field interference, and safety distances between electrical devices, pulsed magnet and people in strong electromagnetic field environment are determined by electromagnetic field simulation. A bidirectional repeating pulsed magnetic field with a peak field of+6.2T/-3.8T (adjustable), a pulsed power supply of1.5kV/45kJ (adjustable), a pulse width of193ms, a peak pulsed current of802A (adjustable) and a cycle of4.2s (adjustable) are obtained. The experiments results of the proposed repeating pulsed magnetic system meet the magnetic refrigeration requirement. Compared with the existing repeating pulsed magnetic system, ours gets breakthrough in longer pulse width, and it represents a new choice for magnet system of magnetic refrigeration technology. |
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