Stability Analysis And Integrative Protection System Design On Small-Scale Experimental Superconducting Magnet

Superconducting magnet's characteristic is that it can produce strong magnetic field in large area with the low supplied power, and the field keeps constant at the superconducting condition. At the present time, the technologies of superconducting magnets are successfully applied in different domains, such as science researching, electrical power system, railway traffic, medical treatment and so on.The research object of this dissertation is the small-scale NbTi superconducting magnet, which has the requirement of quickly energy-transferring used in experimental research. The paper firstly summarizes the development of superconductivity and the technology of superconducting magnets, then the researching background is simply introduced. According to the experimental magnet, the paper analyzes magnet's stability and insulated structure. The stability of the magnet is analyzed in adiabatic condition, and the hot spot is also estimated to check the maximum temperature of the magnet after quenching, and this is the basic analysis for quench protection. Magnet's quench transmitting property is researched to master the changes of magnet's inner resistance, and this is good academic foundation for the magnet's quench detection and protection. Comparing with other methods of quench detection, the method of voltage detecting is better and more popular for the magnet's protection. In order to ensure magnet's safety when it running, the paper adopt different protective methods when the magnet works in different phases, and it's helpful for the magnet's protection, the designed system includes two parts: quench protection and over-voltage protection. The circuits are calculated and simulated to satisfy the requirement of the protective system, such as electrical bridge circuit, absolute value circuit and so on. Two methods of keeping the voltage as the constant are also discussed in the paper, comparing with the ordinary ways, these methods can evidencely improve the speed of the discharge, and the energy-transfer efficiency becomes higher.Finally, a new method based on detecting the changes of magnet's inner resistance for quench detection is put forward, and it can be very useful for advancing the magnets' stability.