Research On Alternating Loss Of High Temperature Superconductor Suspension System And Design Of Optimal Control Algorithm

This article mainly focus on the shortcomings as heat-ness and core saturation of the electro-magnetics,which is used in normal conducting maglev system that has been into commercial use recently.And the article combines the status quo of preparation techniques and application technology of YBCO,then puts forward a superconduct levitation scheme.This article mainly carries on the construction design and simulation verification of the levitation magnet,does research on the alternative loss of the HTS levitation system and makes simulation and experiments,puts up the performance index of the optimization of alternative loss,finally solves the optimal controller.The article creates the method of the measurement of critical magnetic field called”six-lines method”,simulates the critical current of HTS maglev constructions and combines the characteristic curve of critical current of HTS materials to reach the solutions.First of all,the HTS levitation scheme based on YBCO superconducting coils is able to provide sufficient levitation force.Then,in the circumstance of 77 K,the critical current in superconducting coils is about 120 A,considering the margin of 20%,the working current in coils cannot be above 96 A,but in engineering,the levitation current is usually under 60 A,so it is considered that the superconducting current can satisfy the constrained condition.While the superconducting maglev system is in stable working condition,its exciting current is a special form called “alternating-direct current”,i.e.,adding a dynamic alternating current component in a steady direct current,but the research of the loss related to the superconducting system is rare.The article reaches the conclusion by simulation and experiment measurement of alternating loss in YBCO strip and coils which is positive correlated to the current frequency and alternating components,while fluctuating with direct components and the loss reaches its maximum in around 30 A.Therefore,if the direct component raised to 50 A,the direct loss decreases rapidly,thus making the demand of materials decreased.No matter in the view of reducing the use of material or cutting down the energy consumption of the whole system,the cost will be saved.By modeling and linearizing the HTS levitation system,this article carries out the constrained condition of HTS levitation current,and creatively puts out the quantitive relationship of index of the alternating loss and specific direct component,alternating component and frequency uniformization.Then the article carries out the performance index of the optimal alternating loss based on HTS levitation system model,then uses the linear quadratic type to solve the the optimal controller.Finally,its stability,robustness and dynamic performance is verified by simulation and it is shown that the design satisfies the demand of the levitation system,thus the feasibility of the control method is verified.To conclude,this article considered that the HTS suspension system is feasible and it is necessary to build a intergraded experiment platform to test and analyze.