Proposal of a novel design for linear superconducting motor using 2G tape stacks

This paper presents a new design for a su- perconducting linear motor (SLM). This SLM uses stacks of second-generation (2G) superconducting tapes, which are responsible for replacing yttrium barium copper oxide bulks. The proposed SLM may operate as a synchronous motor or as a hysteresis motor, depending on the load force magnitude. A small-scale linear machine prototype with 2G stacks was constructed and tested to investigate the proposed SLM topology. The stator traveling magnetic field wave was represented by several Nd-Fe-B permanent magnets. A relative movement was produced between the stator and the stack, and the force was measured along the displacement. This system was also simulated by the finite element method, in order to calculate the induced currents in the stack and determine the electromagnetic force. The H-formulation was used to solve the problem, and a power law relation was applied to take into account the intrin- sically nonlinearity of the superconductor. The simulated and measured results were in accordance. Simulated re- sults were extrapolated, proving to be an interesting tool to scale up the motor in future projects. The proposed motor presented an estimated force density of almost 500 N/kg, which is much higher than any linear motor.This work was supported in part by the following agencies: CNPq/CAPES/INERGE, CNPq—Ci ˆ encias sem Fronteiras, FAPERJ, Catalan Government 2014- SGR-753, CONSOLIDER Excellence Network MAT2014-56063-C2-1-R and MAT2015-68994-REDC, Eurofusion EU COST ACTIONS MP1201/ MP1014/PPPT-WPMAG 2014, EUROTAPES FP7-NMP-Large-2011- 280432, FORTISSIMO FP7-2013-ICT-609029, and Spanish Govern- ment Agencies—Severo Ochoa Programme Centres of Excellence in R&D. (Corresponding author: Guilherme G. Sotelo.

무절연 고온초전도 계자 권선의 초전도 동기 모터 적용성 연구

학위논문(박사) -- 서울대학교대학원 : 공과대학 전기·정보공학부, 2022. 8. 한승용.최근 지구온난화가 가속화됨에 따라 세계 각국에서는 탄소중립을 달성하기 위하여 온실가스 배출을 줄이기 위한 기술 연구를 활발하게 수행하고 있다. 온실가스 저감을 위한 노력은 전력시스템, 수송, 제조 산업, 생활 건물 등 사회 전 분야에서 이뤄지고 있다. 이중 특히 대형 화물 트럭, 선박 및 항공기를 포함하는 수송 분야에서는 온실가스 배출을 획기적으로 절감하기 위하여 기존 화석연료 기반 추진 시스템을 대체할 수 있는 수소 혹은 전기 에너지 기반의 새로운 고성능 추진 시스템의 개발이 요구되고 있다. 대체 연료에 기반한 추진 시스템 개발 시 중요하게 여겨지는 부분 중 하나는 경량화 및 소형화를 위한 추진 시스템의 출력 및 에너지 밀도의 향상이다. 고온초전도 모터를 기반으로 하는 전기추진 시스템은 고온초전도 코일의 높은 통전 전류를 기반으로 기존 상전도 기반 시스템을 뛰어넘는 높은 출력밀도를 달성할 수 있을 것으로 예상된다. 이에 따라 전기추진 항공기 등 차세대 수송 시스템에 적용하기 위한 고온초전도 전기추진 시스템 개발 프로젝트가 미국, 일본, 유럽을 포함한 선진국들을 중심으로 착수되어 진행되고 있다. 기존 고온초전도 모터의 기술적 난제 중 하나로써 고온초전도 계자 권선의 운전 안정성과 보호의 어려움이 지속적으로 논의되어 왔다. 이를 개선하기 위하여 무절연 고온초전도 권선 기술을 적용한 무절연 고온초전도 모터 개념이 제안되었다. 무절연 고온초전도 권선 기술은 초전도 턴간의 절연을 제거함으로써 고온초전도 코일의 운전 신뢰성을 크게 향상 시킨 기술로써, 퀜치 사고 시 코일의 보호에 매우 효과적임이 실험적으로 여러 차례 검증된 바 있다. 하지만, 턴간의 절연 제거로 인하여 무절연 고온초전도 계자 권선의 누설 전류가 발생에 따라 일반적인 절연된 계자 권선과 다소 다른 운전 특성을 보일 수 있으며, 이러한 무절연 특성에서 비롯된 운전 특성으로 인하여 무절연 계자 권선이 실제 모터에 적용 가능한 기술인지에 대한 논의가 필요하다. 이를 위해서, 무절연 계자 권선을 모터에 적용할 시 운전 특성을 해석하기 위한 모델의 수립과 실험을 통한 특성 분석 연구가 요구된다. 본 연구에서는, 무절연 고온초전도 계자 권선의 초전도 모터에의 적용 가능성에 대하여 논의하였다. 이를 위하여 기존에 제시된 절연 초전도 코일과 무절연 초전도 코일의 해석 기법들을 바탕으로, 무절연 특성이 반영된 무절연 고온초전도 모터의 해석 모델을 최초로 제시하고 이를 바탕으로한 해석을 수행하였다. 또한, 실제 실험을 통한 특성 분석을 위하여 무절연 계자 권선을 적용한 특성 시험 장치의 설계 및 제작을 수행하였다. 액체질소 기반 냉각 시스템과 초전도 모터 시험을 위한 다이나모 실험 장치를 구축하였으며, 설계 시 고려되어야 하는 주요 전기적, 구조적, 열적 특성을 분석하여 이를 설계에 반영하였다. 구축한 시험장치를 이용하여 무절연 계자 권선이 적용된 시험용 모터를 다양한 조건에서 운전을 수행하였고, 이 때 나타나는 무절연 고온초전도 계자 권선의 응답 특성을 최초로 관측하고 정리하였다. 무절연 고온초전도 계자 권선에서 나타나는 응답 특성의 원인을 시험 시스템의 조건을 고려하여 제안한 해석모델을 통해 분석하였고, 이러한 무절연 고온초전도 계자 권선의 응답이 모터의 운전 특성에 어떠한 영향을 미칠 수 있는지 논의하였다. 마지막으로, 실제 모터에 무절연 고온초전도 계자권선을 적용하기 위한 개선점들과 추가적인 연구의 필요성에 대하여 정리하였다.As global warming becomes a significant issue in recent years, major countries around the world are actively developing technical solutions to reduce greenhouse gas emissions in all areas of society to achieve carbon neutrality. Major fields requiring greenhouse gas reduction can be broadly classified into power systems, buildings, transportation, and industry. In particular, in the transportation field, which includes the operation of large cargo trucks, ships, and aircraft, the development of a new high-performance propulsion system based on alternative fuels like hydrogen or electricity is necessary to replace the conventional fossil fuel-based propulsion system. One of the important aspects in the development of an alternative fuel-based propulsion system is the improvement of the power density and energy density to achieve lightweight and small sizes. An electric propulsion system adopting a superconducting motor is expected to achieve high power density based on the high current density of a superconductor coil compared to a non-superconducting counterpart. Hence, for the development of eco-friendly propulsion systems in the next generation, various superconducting propulsion system development projects have been launched and conducted. The operation reliability and protection problem of high-temperature superconductor (HTS) winding have been one of the key challenges for conventional HTS motors. A new concept of a no-insulation (NI) HTS motor adopting an NI HTS coil as a field winding was proposed to improve the operation reliability and protection of the HTS motor. NI HTS winding technology, which intentionally removes insulation between turns of the HTS coil, has been used to construct ultra-high field superconductor magnets, and its improved protection performance has been experimentally verified several times. However, in the case of a field winding in a superconducting motor, NI HTS field winding might affect the operating characteristics of the motor and could operate differently from those of the conventional insulated field winding, due to the leakage current between turns. Due to the unknown operation characteristics that might be derived from unique NI behaviors, it is necessary to discuss whether NI HTS field winding can be a potential option applicable to actual motors. Therefore, derivation of the analysis model and experimental verification are necessary to understand the operating characteristics of an NI HTS motor. In this study, the applicability of NI HTS field winding to superconducting motors was discussed. First, based on the previously presented analysis techniques for insulated HTS coils and NI HTS coils, the first analysis model of a NI HTS motor considering NI characteristics was presented, and an analysis of operation characteristics was performed based on the suggested model. In addition, for the experimental investigations, the design and construction of a test machine with NI HTS field winding and an experiment system were conducted. The liquid nitrogen-based cooling system and dynamo test facility were constructed and major electrical, structural, and thermal characteristics that should be considered in the design were analyzed and applied to the system. The test motor with NI HTS field winding was operated under various conditions, and the nonlinear responses of NI HTS field winding were observed for the first time. The mechanism of the observed nonlinear responses of the NI HTS field winding was analyzed through the proposed analysis model considering the conditions of the test system, and how these responses of the NI HTS field winding could affect the operating characteristics of the motor was discussed. Finally, additional required studies and improvements for applying NI HTS field winding to actual motors were discussed.1 INTRODUCTION 1 1.1 Superconducting Electric Propulsion System for Next-generation Mobility 1 1.1.1 Requirements of Alternative-fueled Transportation for Net-zero 2050 1 1.1.2 Basic Concept and General Properties of Superconducting Motor 5 1.1.3 Previous Cases, Current Trends, and Key Challenges 8 1.2 No-insulation High-temperature Superconductor Coil as Potential Technical Solution for Superconducting Motor 13 1.2.1 Background of No-insulation High-temperature Superconductor Coil 14 1.2.2 Applicability of No-insulation High-temperature Superconductor Coil to Superconducting Motor 17 1.2.3 What Needs to be Studied for NI HTS Motor: Requirements of Analysis Model and Experimental Study 20 1.3 Goal and Significance of this Study 22 1.4 Structure of the Thesis 23 2 THEORETICAL BACKGROUND ON SUPERCONDUCTIVITY AND SUPERCONDUCTOR WIRE 25 2.1 Superconductivity 25 2.2 Classification of Superconductors 26 2.2.1 Type-I and Type-II Superconductor 26 2.2.2 Low-temperature Superconductor and High-temperature Superconductor 27 2.3 Key Properties of (RE)Ba2Cu3O7x Coated Conductor 30 3 ANALYSIS METHODS OF COIL AND ROTATING MACHINE ADOPTING NO-INSULATION TECHNIQUE 33 3.1 Electromagnetic Analysis Model of Superconductor Coil 34 3.1.1 Magnetic Field Analysis Based on Finite Element Method 34 3.1.2 Critical Current Estimation with Load Line Method 37 3.2 Analysis Model of NI Characteristics in NI HTS Coil 38 3.3 The First Non-linear Analysis Models for NI HTS Motor 44 3.3.1 Equivalent Circuit Model of Synchronous Motor with NI HTS Field Winding 44 3.3.2 Finite Element Method Analysis Model Combined with Lumped Parameter Circuit Model 46 4 DESIGN OF TEST MACHINE AND EXPERIMENTAL SYSTEM FOR APPLICABILITY TEST OF NI HTS FIELD WINDING 49 4.1 Electromagnetic Design of Test Machine for Experiment 49 4.1.1 Purpose of Test System and Overall Design Directions 50 4.1.2 Electromagnetic Design Based on Parameter Sweep 52 4.1.3 Operation Characteristics Analysis of Designed Test Machine 59 4.2 Rotor Assembly and Cryogenic System Design for Experiment 73 4.2.1 Rotor Assembly Design and Mechanical Characteristics Analysis 75 4.2.2 LN2 Chamber Design and Thermal Loss Estimation 82 4.2.3 Conceptual Design of Dynamo Test System with LN2 Cooling 92 5 CONSTRUCTION OF TEST MACHINE AND EXPERIMENT SYSTEM 95 5.1 Fabrication of NI HTS Racetrack Coils 95 5.1.1 NI HTS Single Pancake Racetrack Coil Winding 95 5.1.2 Performance Inspection of Wound NI HTS Racetrack Coils 97 5.2 Construction of Test Machine with Wound NI HTS Racetrack Coils 101 5.3 Experiment System Construction 105 5.3.1 Construction of Axial Type Dynamo Test System 105 5.3.2 Power Supply, Motor Drive System, and Measurement Instruments 107 6 EXPERIMENTAL STUDY ON APPLICABILITY OF NI HTS FIELD WINDING TO SUPERCONDUCTING MOTOR 110 6.1 Overview on Tests: Key Questions, Test Plans, and Test Procedure 111 6.1.1 Theoretical Expectations Based on Suggested Analysis Model 111 6.1.2 Test Plans and Overall Test Procedure 112 6.2 Test 1: Interaction Between Stator Winding and NI HTS Field Winding 115 6.2.1 Experiment Scenarios, Results, and Key Findings 115 6.2.2 Detailed Analysis on Response of NI HTS Field Winding 119 6.3 Test 2: Steady-state Operation Characteristics of NI HTS Test Machine 121 6.3.1 Selected Experiment Results and Key Findings 121 6.3.2 Detailed Analysis on Ripple Response of NI HTS FieldWinding 128 6.4 Test 3: Transient Operation Characteristics of NI HTS Test Machine 135 6.4.1 Experiment Scenarios, Results, and Key Findings 136 6.4.2 Detailed Analysis on Transient Behavior of NI HTS FieldWinding 138 6.5 Experiment Summary and Lessons Learned 144 6.5.1 Summary on Key Findings 144 6.5.2 Lessons Learned, Potential Challenges, and Required Improvements 145 7 CONCLUSION 151 A APPENDICES 154 A.1 Bending Strain of REBCO Coated Conductor 154 A.2 Derivation of Effective Mechanical Properties 155 A.3 Stability and Protection Properties of NI HTS Coil 160 A.4 Detailed Simulink Modeling for Transient Simulation 165 Bibliography 170 Abstract (In Korean) 186박

High Efficiency Megawatt Motor Preliminary Design

The High Efficiency Megawatt Motor (HEMM) is being designed to meet the needs of Electrified Aircraft Propulsion (EAP). A preliminary design has been completed and risk reduction activities are being conducted in three key areas: cryogenic cooler design, superconducting rotor coil design and manufacturing, and stator thermal management. The key objective of HEMM is to establish a motor technology which simultaneously attains high specific power (>16kW/kg ratio to electromagnetic weight) and high efficiency (>98%) by judicious application of high temperature superconducting wire and integrated thermal management. Another important feature is to achieve the performance goals with an eye to aircraft integration constraints. An electromagnetic analysis was performed which shows that the proposed HEMM design meets the performance objectives if key current capability and mechanical constraints are achieved. The risk reduction activities are the first assessment of the key design features. The HEMM technology could be applied to a range of aircraft types that require megawatt level electrical power

Design of an HTS levitated double-sided HTSLSM for maglev

© 2012 Published by Elsevier B.V. Selection and/or peer-review under responsibility of the Guest Editors. A hybrid high temperature superconducting (HTS) linear synchronous propulsion system composed of a double-sided HTS linear synchronous motor (HTSLSM) in the middle and HTS magnetic suspension sub-systems on both sides has been proposed for a middle-low-speed maglev. Three carriages has been made up for the proposed maglev, and each carriage consists of four HTSLSM modules. The HTSLSM has been designed to reach a speed of 69 km/h and a maximum thrust of 48.9 kN for each motor. The finite element analysis has been used for the theoretical verification. The results obtained show that the HTS linear propulsion system satisfies the principal requirements for the maglev

Characteristics and Optimization of a PMLSM for HTS Magnetic Suspension Propulsion System

¾Permanent magnet (PM) linear synchronous motors (PMLSMs) can be integrated with a high temperature superconducting (HTS) magnetic suspension system to be used in such as electromagnetic aircraft launcher and maglev transportation which have a levitated object moving on a long linear track. This paper presents the design and electromagnetic characteristic analysis of a long-primary single-sided PMLSM for a HTS bulk-PM guideway repulsion magnetic suspension propulsion system. Based on the characteristics and performance analysis of the PMLSM, a new type of HTS suspension propulsion system driven by a double-sided PMLSM with an optimal PM structure is then proposed. The running characteristics of the linear propulsion systems are studied through finite element analysis (FEA) with comprehensive performance results obtained for practical development

Superconducting electromagnetic launch system for civil aircraft

This paper considers the feasibility of different superconducting technologies for electromagnetic launch (EML) to assist civil aircraft take-off. EML has the potential of reducing the required runway length by increasing aircraft acceleration. Expensive airport extensions to face constant air traffic growth could be avoided by allowing large aircraft to operate from short runways at small airports. The new system positively affects total aircraft noise and exhaust emissions near airports and improves overall aircraft efficiency through reducing engine design constraints. Superconducting Linear Synchronous Motors (SCLSMs) can be exploited to deliver the required take-off thrust with electromagnetic performance that cannot be easily achieved by conventional electrical machines. The sizing procedure of a SCLSM able to launch A320 in weight is presented. Electromagnetic and thermal aspects of the machine are taken into account including the modelling of ac losses in superconductors and thermal insulation. The metallic high temperature superconductor (HTS) magnesium diboride (MgB2) is used and operated at 20 K, the boiling temperature of liquid hydrogen. With modern manufacturing technology, multifilament MgB2 wires appear to be the most cost-effective solution for this application. Finally the impact of the cryocooler efficiency on the machine performance is evaluated