Research On The Mechanical Characteristics Of A Cylindrical Three-Phase Linear Motor With High-Temperature Superconducting Magnets As The Magnetic Poles

As the high-temperature superconducting (HTS) technology can make motors more efficient and miniaturized, it has been applied to motor technology earlier. In the field of rotating motors, the research results have proved their superiority. Linear motors aim at higher efficiency, thus, HTS technology becomes more important in high-thrust linear motors. Nowadays, HTS linear motors have a variety of different designs. Some scholars researched on using HTS wire instead of copper wire to make the armature of the linear motor. Such designs have greatly reduced the volume of the armature, but the problem of AC losses affects the performance of the motor. Other scholars used HTS bulks or HTS wire-windings as the magnetic poles of the linear synchronous motor to improve performance. Most of the researches are about the flat linear motors, and there are only a few researches about the cylindrical linear motors. However, the cylindrical linear motors are widely applied under limits, such as oil pumps and machine tools. Therefore, the researches on the HTS cylindrical linear motors are meaningful. The only experimental researches of the cylindrical linear motors are using HTS wire to make the armature, and using HTS materials as the magnetic poles of the linear motor is only a concept of some scholars. This paper focuses on how to, by the concepts, design and make a motor model composed of a cylindrical three-phase linear windings made of copper wire and magnetic poles made of HTS bulks or HTS coils to study the mechanical characteristics of the motor through some experiments and simulations.Firstly, we measure the characteristics of the traveling magnetic fields and the trapped magnetic fields of the HTS bulk. The static thrusts of the HTS bulk magnets under the traveling magnetic fields are studied in experiments. At the temperature of 77 K and the RMS current of 10 A for the armature coils at a frequency of 20 Hz, with a charging magnetization current of 40 A for one YBCO bulk, a peak thrust of 27.2 N is measured. Effects of armature RMS current and frequency, charging magnetization current, running time, magnetizers are discussed. The thrusts of more than one HTS bulk magnets and the induced thrusts of one HTS bulk magnet are also studied. Finally, we study the motions of the HTS bulk magnets in the experiments.Secondly, this paper introduces the design parameters of the HTS single pancake and double pancake coil magnets. The static thrusts of the HTS coil magnets under the traveling magnetic fields are studied in experiments. At the temperature of 77 K and the RMS current of 10 A for the armature coils at a frequency of 20 Hz, with excitation currents of 40 A for one YBCO single pancake coil and one YBCO double pancake coil, peak thrusts of 2.1 N and 3.8 N are measured, respectively. Effects of armature RMS current and frequency, excitation current, running time, magnetizers and seams between magnetizers are discussed. The thrusts of more than one HTS coil magnets and the induced thrusts of one closing HTS coil magnet are also studied. Finally, we study the motions of the closing HTS coil magnet in the experiments.And finally, the theoretical analysis and the simulation calculation are used to study the cylindrical three-phase linear motor with HTS magnets as the magnetic poles. This paper first analyzes the motor using the analytic method. And then, the motor was modeled and simulated using the finite element method. The comparisons are made between the theoretical results and the simulation results and the experimental results. Therefore, the effectiveness for the theoretical model and the simulation model has been verified. Effects of structure parameters of HTS coil magnets on the thrusts are studied through making the simulation model, including the number of turns and height of the coil, the size of magnetizers. Effects of the cylindrical three-phase linear winding type are also studied.This paper has found out a new direction of the development of HTS linear motor technology. It provides the basis for designing HTS cylindrical linear motors, and will serve as the foundation of the research on the large-scale practical HTS cylindrical linear motors in the future.