In this paper, the electromagnetic design of a 10-MW-class high-temperature superconducting (HTS) wind turbine synchronous generator is discussed The primary designed machine is modeled using a finite-element method, and the generator characteristics are obtained As one of the most important characteristics of a generator is voltage harmonics contents, excitation field winding dimensions through sensitivity analysis are optimized in order to reduce voltage and magnetic field harmonics Behavior of both the excitation field winding producing magnetic flux density and voltage harmonic components by varying HTS coil width and height is obtained This paper shows that output voltage harmonics contents of the proposed generator are sensitive to the excitation field coil dimensions

Design of a 10-MW-Class Wind Turbine HTS Synchronous Generator With Optimized Field Winding

This paper describes the passive quench protection system selected for the muon ionization cooling experiment (MICE) cooling channel coupling magnet. The MICE coupling magnet will employ two methods of quench protection simultaneously. The most important method of quench protection in the coupling magnet is the subdivision of the coil. Cold diodes and resistors are put across the subdivisions to reduce both the voltage to ground and the hot-spot temperature. The second method of quench protection is quench-back from the mandrel, which speeds up the spread of the normal region within the coils. Combining quench back with coil subdivision will reduce the hot spot temperature further. This paper explores the effect on the quench process of the number of coil sub-divisions, the quench propagation velocity within the magnet, and the shunt resistance.

/pdf/quench-protection-for-the-mice-cooling-channel-coupling-4kndg4cb9f.pdf

Quench Protection for the MICE Cooling Channel Coupling Magnet

High temperature superconducting (HTS) armature windings have the potential for increasing the electric loading of a synchronous generator due to their high current transport capacity, which could increase the power density of an HTS rotating machine In this work, a novel synchronous generator prototype with an HTS stator and permanent magnet rotor has been developed It has a basic structure of four poles and six slots The armature winding was constructed from six double-pancake race-track coils with 44 turns each It was designed to deliver 25 kW at 300 rpm A concentrated winding configuration was proposed, to prevent interference at the ends of adjacent HTS coils The HTS stator was pressure mounted into a hollow Dewar cooled with liquid nitrogen The whole stator could be cooled down to around 82 K by conduction cooling In the preliminary testing, the machine worked properly and could deliver 18 kW power when the armature current was 144 A Ic for the HTS coils was found to be suppressed due to the influence of the temperature and the leakage field

https://iopscience.iop.org/article/10.1088/0953-2048/27/4/044026/pdf

Development and testing of a 2.5?kW synchronous generator with a high temperature superconducting stator and permanent magnet rotor

This paper focuses on the comparison of electromagnetic performance of the superconducting permanent magnet (SCPM) generators with two different topologies. The torque capabilities of the two generators are first investigated. The peak torque is largely restricted by the material characteristics of the superconducting (SC) and the permanent magnet. The SCPM generators with iron-cored rotor and iron-cored stator topology (IRIST) is superior to the one with iron-cored rotor and air-cored stator topology in terms of torque capability. Furthermore, the flux density, line electromotive force, torque and its torque ripple, and the efficiency of the designed generators are evaluated by using numerical model. The simulation results confirm that IRIST has higher output torque and efficiency with the penalty of higher harmonics and torque ripples.

/pdf/comparison-of-electromagnetic-performance-of-scpm-wind-power-1ehlqm7a5v.pdf

Comparison of Electromagnetic Performance of SCPM Wind Power Generators With Different Topologies

The purpose of the MICE spectrometer solenoid is to provide a uniform field for a scintillating fiber tracker. The uniform field is produced by a long center coil and two short end coils. Together, they produce 4T field with a uniformity of better than 1% over a detector region of 1000 mm long and 300 mm in diameter. Throughout most of the detector region, the field uniformity is better than 0.3%. In addition to the uniform field coils, we have two match coils. These two coils can be independently adjusted to match uniform field region to the focusing coil field. The coil package length is 2544 mm. We present the spectrometer solenoid cold mass design, the powering and quench protection circuits, and the cryogenic cooling system based on using three cryocoolers with re-condensers.

/pdf/the-design-and-construction-of-the-mice-spectrometer-384fi2cpqu.pdf

The Design and Construction of the MICE Spectrometer Solenoids

The Muon Ionization Cooling Experiment (MICE) will demonstrate ionization cooling in a short section of a realistic cooling channel using a muon beam at Rutherford Appleton Laboratory in the UK. The coupling magnet is a superconducting solenoid mounted around four 201 MHz RF cavities, which produces magnetic field up to 2.6 T on the magnet centerline to keep muons within the iris of RF cavities windows. The coupling coil with inner radius of 750 mm, length of 285 mm and thickness of 102.5 mm will be cooled by a pair of 1.5 W at 4.2 K small coolers. This paper will introduce the updated engineering design of the coupling magnet made by ICST in China. The detailed analyses on magnetic fields, stresses induced during the processes of winding, cool down and charging, and cold mass support assembly are presented as well.

/pdf/magnetic-and-cryogenic-design-of-mice-coupling-solenoid-3dh983gktl.pdf

Magnetic and Cryogenic Design of MICE Coupling Solenoid Magnet System

The RF coupling coil (RFCC) module of MICE is where muons that have been cooled within the MICE absorber focus (AFC) modules are re-accelerated to their original longitudinal momentum. The RFCC module consists of four 201.25 MHz RF cavities in a 1.4 meter diameter vacuum vessel. The muons are kept within the RF cavities by the magnetic field generated by a superconducting coupling solenoid that goes around the RF cavities. The coupling solenoid will be cooled using a pair of 4 K pulse tube cooler that will generate 1.5 W of cooling at 4.2 K. The magnet will be powered using a 300 A two-quadrant power supply. This report describes the ICST engineering design of the coupling solenoid for MICE.

/pdf/the-engineering-design-of-the-1-5-m-diameter-solenoid-for-2qfdtshhmy.pdf

The Engineering Design of the 1.5 m Diameter Solenoid for the MICE RFCC Modules

A 400 kW radial-axial flux type experimental HTS synchronous motor is designed. There are twelve armature coils used HTS wires in the motor. They are accommodated in the cooling vessels made of FRP material, and twelve cooling vessels are enclosed in the vacuum vessel. In order to cool the HTS coils of the motor, a sub-cooled liquid nitrogen cryogenic system is presented. The operation temperature is below 70 K. This system consists of HTS coils cryostats, liquid nitrogen transfer-line, liquid nitrogen dewar and a cold box with liquid nitrogen pump, G-M cryorefrigerators and some control valves inside. In this paper, different kinds of the heat loads of the system including the AC loss, current lead, supporters and radiation are presented. Basis on the heat load and operating temperature, the main parameters and equipments of the system are determined.

Design of the Cryogenic System for a 400 kW Experimental HTS Synchronous Motor

A 400 kW radial-axial flux type experimental HTS synchronous motor is designed. There are twelve armature coils using HTS wires in the motor. They are accommodated in the cooling vessels made of FRP material, and twelve cooling vessels are enclosed in the vacuum vessel. In order to cool the HTS coils of the motor, a sub-cooled liquid nitrogen cryogenic system is presented. The operation temperature is below 70 K. This system consists of vacuum system, liquid nitrogen dewar, data acquisition system and a cold box with liquid nitrogen pump, G-M cryorefrigerator, cryogenic valve and a heater inside. The heater can present the heat of the HTS coils. In this paper, the design and the composition of this test cooling system are presented. When liquid nitrogen is injected into the vessel and the cryorefrigerator is operating, the cool down curve of the test system is obtained. After adding heat to the system, the capacity curve of the system is presented in this paper. The results proved that this sub-cooled liquid nitrogen system can be used for cooling the actual armature windings in the HTS motor.

Sub-Cooled Liquid Nitrogen Test System for Cooling HTS Synchronous Motor

The invention provides a constant-tension winding machine for niobium titanium-copper superconducting solenoid coils, relating to a winding machine for superconducting solenoid coils. The invention solves the problems of complex winding process, high labor intensity of operators and low use ratio of equipment space of the current winding machine for superconducting solenoid coils. In the invention, an L-shaped portal frame is provided with two first slider linear guide rails and a first ball screw, and a double-track pulley is installed on a wiring arm. A wiring support arm of the wiring arm is provided with a wiring pulley, and a wire loading support arm of the wiring arm is provided with a wire loading pulley. A movable pulley is installed on a movable pulley axis support, and a wire loading tray is rotatably installed on a wire loading support. A superconducting solenoid coil to be wound is rotatably installed on a winding support, and a lead wire is led out through the wire loading tray and wound on the superconducting solenoid coil to be wound after moving round the wire loading pulley, one slideway of the double-track pulley, the movable pulley, the other slideway of the double-track pulley and the wiring pulley. The constant-tension winding machine is suitable for winding niobium titanium-copper superconducting solenoid coils.

Fengyu Xu

Papers

Magnetic and Cryogenic Design of MICE Coupling Solenoid Magnet System

The Engineering Design of the 1.5 m Diameter Solenoid for the MICE RFCC Modules

Design of the Cryogenic System for a 400 kW Experimental HTS Synchronous Motor

Sub-Cooled Liquid Nitrogen Test System for Cooling HTS Synchronous Motor

Constant-tension winding machine for niobium titanium-copper superconducting solenoid coils