Luhai Zheng

Thrust characteristics of a double-sided high temperature superconducting linear synchronous motor with a high temperature superconducting magnetic suspension system

An electromagnetic design of a double-sided high temperature superconducting (HTS) linear synchronous motor (HTSLSM) with an HTS bulk magnet secondary is introduced in this paper. A HTS magnetic suspension system is applied to replace the sliding rail to levitate the secondary mover resulting in the HTSLSM moving without sliding friction. The thrust model of the HTSLSM is built using a magnetic circuit method and the thrust characteristics obtained from the model are compared with finite element analysis and practical testing results. The theoretical analysis on the prototype has also been verified by measurements.

Performance Analysis of an HTS Magnetic Suspension and Propulsion System With a Double-Sided HTS Linear Synchronous Motor

A novel HTS magnetic suspension and propulsion system driven by a double-sided HTS linear synchronous motor (HTSLSM) has been developed, which is suspended by an HTS magnetic suspension subsystem located on the bottom of the HTSLSM secondary mover. The structural design of the suspension and propulsion system is introduced, and then the magnetization characteristics of the HTS bulk magnets for the HTSLSM are studied and compared by different magnetization methods. The finite-element analysis (FEA) model of the HTSLSM is built up by using an equivalent model of the HTS bulk magnet, and the thrust characteristics of the HTSLSM are also simulated based on the FEA model, and verified by measurements on the prototype. Furthermore, the suspension performance of the HTS magnetic suspension subsystem has also been analyzed by a numerical method based on an equivalent current sheet model of the permanent-magnet guideway. The results show that the HTS magnetic suspension and propulsion system has applicable thrust and suspension performance, and can be applied to the practical applications such as a maglev.

Influence of external traveling-wave magnetic field on trapped field of a high temperature superconducting bulk magnet used in a linear synchronous motor

A single-sided high temperature superconducting (HTS) linear synchronous motor (HTSLSM) has been developed with a pulse magnetization system to obtain the HTS bulk magnet array with alternating magnetic poles for the motor secondary. In order to identify the trapped field characteristics of the HTS bulk magnet exposed to the external traveling-wave magnetic field generated by the primary of the HTSLSM, a measurement system has been built up and the relevant experiments have been carried out. The relationships between the trapped field attenuation of the HTS bulk magnet and the amplitude, frequency and acting direction of the external traveling-wave magnetic field are experimentally obtained to allow the HTSLSM characteristics to be practically verified.

Investigation of HTS bulk magnet linear synchronous motors

A high temperature superconducting (HTS) linear synchronous motor (LSM) using HTS bulk magnets as secondary has lots of advantages than conventional permanent magnet (PM) LSM, such as smaller volume, less weight, bigger propulsion and so on. In this paper, the numerical model and equivalent magnetic-circuit of a HTS-LSM are built with results are presented. The magnetic field distribution and thrust force characteristics of the HTS-LSM are studied based on finite element method, and the analysis results are compared for different sizes of HTS bulk. The control strategy of Voltage Space Vector PWM (SVPWM) is applied to the running of the HTS-LSM, and the speed-adjusted system simulation model is also built by Matlab/Simulink lied on the mathematical model of HTS-LSM. This work has important meanings for the further studying of the HTS-LSM technology.

Design and characteristics analysis of long-primary single-sided linear induction motor

Long-primary single-sided linear induction motors (SLIMs) have unique advantages in some applications such as an electromagnetic launcher with higher force density and acceleration due to its lightweight secondary conductive sheet compared with other types of SLIM having different structures. Furthermore, long-primary SLIM will have superiorities without any friction loss and guidance control system when it is combined with high temperature superconducting (HTS) magnetic levitation system. In this work, a long-primary SLIM integrated with HTS levitation system is designed. This paper presents the design and performance analysis of the SLIM levitated by a HTS levitation system, and the magnetic field finite element method is applied to analysis its magnetic flux distribution, thrust force and normal force characteristics with results obtained. Finally, the preliminary motor running testing results are also presented.

Design and electromagnetic analysis of a HTS linear synchronous motor

High temperature superconducting (HTS) linear synchronous motor (LSM) integrated with HTS magnetic levitation system, can realize self-levitation and self-guidance without any sliding friction, which will have important applications in many fields such as electromagnetic aircraft launch system, maglev transportation. This paper presents the design and electromagnetic analysis of a HTS LSM, which is levitated by a magnetic levitation system consisting of HTS bulks-permanent magnet (PM) guideways. Numerical analysis and magnetic field finite element analysis (FEA) methods are applied to analyze the thrust, levitation and guidance force characteristics, and the electromagnetic performance of HTS LSM under no-load and load situations are studied with the analysis results are given. Finally, the primary motor running testing results are provided.

HTS Levitated Mobile Technology and Prototype

The special reaction phenomenon of a high temperature superconductor (HTS) to magnetic fields provides an alternative technical solution for design of a levitated mobilization system, in which a linear motion drive with a HTS incorporated is a critical issue. This work presents the design and performance analysis of a HTS linear synchronous driving system with a prototype built for verification. Magnetic field finite element analyses are conducted to compute the key parameters, and the steady state characteristic of the system is predicted by using the classic phasor voltage equation. A simulation model is also built to analyze the system dynamic performance, and results show that the levitated HTS mobilization system developed can be driven and controlled at the desired speed.

Experimental study on thrust and normal force of a permanent magnet linear synchronous motor

Permanent magnet linear synchronous motor (PMLSM) has important applications in transportation and industrial control systems for its direct thrust and high power density, etc. Thrust and normal force are the most important criteria for the PMLSM, and numerical methods and finite element analysis (FEA) methods have been conduced to evaluate the forces. In this paper, a prototype has been built to measure the thrust and the normal force of a PMLSM Through investigations with experiments, the traits of the thrust and the normal force have been found out, including the trends versus exciting currents with different amplitudes, different air gap lengths, variable magnetic poles, and different magnet arrangements. Conclusions are drawn through experimental analysis benefit to the electromagnetic design and control scheme evaluation for the PMLSM.

Studying the force characteristics of a high temperature superconducting linear synchronous motor

A single-sided high temperature superconducting (HTS) linear synchronous motor (HTSLSM) with an HTS bulk magnet array as its secondary has been developed. A field-cooled magnetization system has also been developed to obtain the magnet array with alternate magnetic poles. In order to identify the performance and force characteristics of the HTSLSM, an equivalent 3D finite element analysis (FEA) model has been built up to analyze its field distributions and cogging force characteristics, and an experimental system has been constructed to measure its thrust and normal force characteristics. The traits of the thrust and the normal force have been extracted by comprehensive experiments, including the trends versus different exciting currents, different air gap lengths and variable magnetic poles. The analysis and experimental results are fundamental to the electromagnetic optimum design and control scheme evaluation for the HTSLSM.

Characteristics of high temprature superconducting bulk magnet

Recent progresses of high temperature superconducting (HTS) bulk technology have made various applications realistic, especially the compact and highly efficient electric motors, magnetic levitation systems and flywheel energy storage systems. In these applications, the HTS bulks are always exposed to the AC external magnetic field. It has previously observed that the trapped magnetic field of a HTS bulk is influenced even attenuated to zero when applied by the AC external magnetic field. Therefore it is important to clarify the trapped field attenuation characteristic in external AC magnetic field. In this work, the trapped field attenuation characteristics of HTS bulk magnet exposed to external AC magnetic field are studied with results presented. The models of HTS bulk with their properties are also summarized. Different magnetization methods are applied to magnetize the HTS bulks, and the magnetization characteristics having differences are illustrated with experimental results.