High Temperature Superconducting Linear Synchronous Motor Integrated With Magnetic Suspension System

Since the discovery of high temperature superconductors (HTS) in 1986, HTS application techniques have been widely developed. Currently, the applicable HTS materials are mainly in the forms of bulks, tapes and thin films, among which, HTS bulks based on Meissner effect and strong magnetic field trapping ability have been widely adopted for potential applications in the maglev, city metro, electric machines, linear motor, high-energy physics etc.After comprehensive research survey of HTS materials applied to HTS linear motors and HTS magnetic suspension systems, the first prototype of HTS linear synchronous motor (HTSLSM) with HTS bulk magnet array as its secondary has been proposed and developed in our laboratory. The HTSLSM in combination with an HTS magnetic suspension sub-system, has been developed in a novel HTS magnetic suspension and linear propulsion system, which brings higher efficiency for its operation with self-levitation and self-guidance capacities without any slide friction loss. Principal work focuses on the studies of the related HTSLSM models and key technologies as summarized below.Firstly, electromagnetic designs of the HTSLSM, including a long-primary stator and an HTS bulk magnet array secondary have been conducted. Two novel magnetization systems for the HTS bulk magnet array has been designed, which can be used to magnetize the HTS bulk array magnet with alternate magnetic poles efficiently. According to practical requirement and the practical parameters of the developed HTSLSM, the theoretical model of the HTS bulk magnet, the numerical model and equivalent finite element analysis (FEA) model of the HTSLSM have been built up, and its electromagnetic parameters are also calculated. The traits of electromagnetic thrust, normal force and the cogging force of the HTSLSM have also been obtained by FEA, which form the theoretical bases for the related measurements on the HTSLSM prototype.Secondly, the HTS magnetic suspension system have been designed with three different types of permanent magnet guideways (PMGs), including surface mounted PMG, flux concentration PMG and Halbach array PMG. In order to study the suspension and guidance characteristics of the HTS magnetic suspension system by numerical method, the equivalent current sheet (ECS) method is used to build up the magnetic field distribution models of the PMGs, which have been verified by relevant measurements. The interaction models between one rectangular or cylindrical HTS bulk and PMG have been built up by numerical method based on the ECS models of the PMGs, which provide effective theory approaches to study the levitation and guidance performance of the HTS magnetic suspension system.Moreover, the experiments to study the magnetization characteristics of the developed HTSLSM, including the DC field-cooled (FC), DC zero-field-cooled (ZFC), and pulse magnetizations for the HTS bulk, have been carried out. The results are helpful to find an optimal magnetization method to obtain HTS bulk magnets for the practical applications. The experimental investigations on the electromagnetic characteristics of the YBCO HTS bulk magnet exposed to the external AC traveling wave magnetic field generated by the linear motor primary have been carried out, and the trapped magnetic field attenuation characteristics of HTS bulk magnet exposed to the external AC magnetic field have been obtained, which forms the theoretical and experimental basis to improve the application performance of HTS bulk magnet for the AC applications.Based on the characteristics of the developed HTSLSM, the corresponding control and measurement systems for the HTSLSM have been developed. By the help of the control and measurement platform, main electromagnetic parameters, thrust and normal force of the HTSLSM have been measured. The methodology is verified by the optimal electromagnetic design and control algorithm analysis of the HTSLSM.Based on the developed HTSLSM model, two types of HTS magnetic suspension and linear propulsion systems driven by a double-sided HTSLSM have been proposed. The applications of the HTS suspension and linear propulsion system on the electromagnetic aircraft launch system (EMALS) and Maglev have been studied, and the design parameters of the propulsion system are obtained based on their practical requirements. Theoretical analysis has been carried out by the FEA.