As the critical barriers to advanced high-temperature superconducting (HTS) device technologies are overcome, practical HTS devices and systems have been enabled and become available for commercial ...application. In identifying the applicability of various HTS devices, their operation principles, characteristics, performance, and efficiency are fundamental. Consequently, the corresponding verification of a wide range of HTS devices, especially the HTS power devices and their system technologies, has been comprehensively carried out, and the analytical results are presented in detail towards their practical applications.
This work covers the high-temperature superconducting (HTS) technologies based on the highlights in recent achievements in the applied HTS field in China. Its comprehensive coverage includes ...practical HTS material manufacturing and characterization, large-scale applications, and electronic applications. The applied HTS technologies have been well enabled to build applicable devices, and their characteristics have been well verified in the HTS devices developed to be industrialized for practical applications. The highlighted HTS devices and their performance details reveal the trend and the necessary improvement required to reach the goal of industrial applications of HTS technologies.
As a bellwether transportation mode, albeit with hot controversy, evacuated tube transport (ETT) can dramatically reduce air friction, and incorporating Maglev technology could also thoroughly ...eliminate wheel-rail friction. It is not difficult to imagine that incorporation of these two technologies could establish an innovative transportation system, with particular advantages in terms of high speed, safety, energy saving, and environmental protection. The integration of these two technologies has been a great challenge, however, due to the composite technology. To realize this revolutionary idea, we have successfully developed the first proof-of-principle prototype of a 45-m-long high-temperature superconducting Maglev evacuated tube transport (HTS Maglev-ETT) test system, called the "Super-Maglev," based on the passive self-stable HTS Maglev conceived in our group in 2000. The system mainly consists of three parts: an HTS Maglev-vehicle-guideway coupling system with 1-t load capability at a levitation gap of 10 mm, a 45-m-long racetrack-type evacuated tube with a 2-m-diameter circular cross section pumped by a hybrid air extraction system, and a 3-m linear induction motor to provide sectional propulsion. The system can achieve a pressure as low as 2.9 kPa in the tube. Experiments show that air drag on the vehicle is greatly reduced at that low air pressure, and a maximum speed of 50 km/h was recorded on the 6-m-diameter test guideway. Theoretically, the reduction of the aerodynamic consumed power could reach as high as to 90% under 10 kPa. This "Super-Maglev" strongly demonstrates the feasibility and potential merits of the HTS Maglev-ETT transportation concept.
With regard to the state-of-the-art technologies in the fields of applied superconductivity and electromagnetic devices, research and development highlights are presented. The recent progress and ...achievement described with principle and technical details include mainly i) applied superconducting materials; ii) superconducting magnets and their applications such as in ITER and Tokamaks; iii) high T c superconducting (HTS) magnetic levitation and applications; iv) HTS smart grids; v) superconducting and electromagnetic material modelling and characterization; and vi) advanced electromagnetic devices. The applied superconductivity technology and availability are especially focused and verified with the trend of development prospection.
HTS synchronous generators, in which the rotor coils are wound from high-Tc superconducting wire, are exciting attention due to their potential to deliver very high torque and power densities. ...However, injection of the large DC currents required by the HTS rotor coils presents a technical challenge. In this paper we discuss the development of a brushless HTS exciter which operates across the cryostat wall to inject a superconducting DC current into the rotor coil circuit. This approach fundamentally alters the thermal load upon the cryogenic system by removing the need for thermally inefficient normal-conducting current leads. We report results from an experimental laboratory device and show that it operates as a constant voltage source with an effective internal resistance. We then discuss the design of a prototype HTS-PM exciter based on our experimental device, and describe its integration with a demonstration HTS generator. This 200 RPM, 10 kW synchronous generator comprises eight double pancake HTS rotor coils which are operated at 30 K, and are energised to 1.5 T field through the injection of 85 A per pole. We show how this excitation can be achieved using an HTS-PM exciter consisting of 12 stator poles of 12 mm YBCO coated-conductor wire and an external permanent magnet rotor. We demonstrate that such an exciter can excite the rotor windings of this generator without forming a thermal-bridge across the cryostat wall. Finally, we provide estimates of the thermal load imposed by our prototype HTS-PM exciter on the rotor cryostat. We show that duty cycle operation of the device ensures that this heat load can be minimised, and that it is substantially lower than that of equivalently-rated conventional current leads.
•Our article represents the outcome of our research and improvement of an existing HTS magnetic bearing. The bearing is improved by altering the rotor's magnetic field configuration and increasing ...the number of stator superconducting windings. Improvements were also achieved by incorporating stacks of composite HTS tapes into the stator design. The relative increase in levitation force in new design is about 20% for the vertical levitation force and about 16% for the radial levitation force.
This paper presents the concept of significant improvements a previously developed magnetic bearing based on non-closed windings made of composite HTS tapes. The magnetic bearing is improved, firstly, by altering the rotor's magnetic field configuration and increasing the number of stator superconducting windings, and, secondly, by incorporating stacks of composite HTS tapes into the stator design. Using numerical simulation methods, passed experimental verification, the load characteristics of the upgraded HTS bearing are predicted. It is demonstrated that using of the Halbach magnetic assembly and additional HTS elements (HTS tapes stacks) not only increases the vertical restoring force but also enhances the radial levitation force component. The relative increase in levitation force per unit superconductor length in the new design is about 20% for the vertical levitation force and about 16% for the radial levitation force. In addition, it has been shown that the use of HTS tapes stacks has a small effect on the vertical force of the bearing and is ineffective in enhancing the support function, but makes a strong contribution to the radial stability of the device and allows the rotor position to be stabilized.
Achieving high values of specific power for electric machines needs application of high temperature superconductors (HTS). Production of HTS machines requires development of calculation methods, ...technology and experimental verification of applied methods. This paper represents the results of calculation and modeling of a 90 kW 6000 rpm synchronous machine with HTS armature winding. The considered machine consists of permanent magnet rotor and 3-phase stator HTS winding which contains 9 double pancake racetrack coils. All coils have been produced and critical current for each coil and n-value were obtained. Machine design was developed. Obtained results allow us to finally assemble the machine and provide experimental research.
A novel double-stator field-modulation high temperature superconducting electrical machine (DSFM-HTSM) has been proposed, in which the armature windings and the HTS magnets are mounted on the outer ...and inner stator respectively, realizing stationary seal of the coolant and brushless transfer of the excitation current. The HTS magnet system is the core component of the DSFM-HTSM, consisting of the HTS magnets and the cryogenic refrigeration system, the design and safe operation of which are a key issue. Therefore, this paper focuses on the thermal loss analysis, design and test methods of the new HTS magnet system for the DSFM-HTSM. An atypical HTS magnet with small dimensions is proposed to suit the topology of the DSFM-HTSM. The different thermal loss sources are carefully analyzed and theoretically calculated, considering the characteristics of each source. The detailed design process of the HTS magnet system is presented. Moreover, an experimental platform is built and tested to verify the validity of the thermal loss analysis and design method. The corresponding research results can lay the foundation for the development and application of the large scale DSFM-HTSM, and can provide some reference for the analysis and design of similar HTS magnet systems.
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