Yutaka Terao

Electromagnetic Design of 10 MW Class Fully Superconducting Wind Turbine Generators

We have studied a 10 MW class fully superconducting synchronous machine for direct-drive wind turbine generators. This machine has been designed using two kinds of superconducting wires. Multifilament wires have been used for armature windings. The DC field coils of the machine rotor are made of HTS tapes. Electromagnetic design of the generators has been carried out by FEM analysis. Analysis results show that 10 MW output is achievable with less use of HTS tapes than wind turbine generators having superconducting field coils and copper armature windings. Then, calculated AC losses are low.

Comparison of Conventional and Superconducting Generator Concepts for Offshore Wind Turbines

This paper deals with the comparison of electromagnetic characteristics of 10 MW class direct-drive wind turbine generators for offshore wind farms. Four kinds of wind turbine generators including a conventional permanent magnet generator, a salient/nonsalient pole superconducting generator, and a fully superconducting generator are investigated. Electromagnetic characteristics for these generators have been investigated with FEM analysis. The results show that a fully and a salient pole type superconducting wind turbine generators have a potential for 10 MW class offshore wind turbine generators from the aspect of size and economical points.

Design study of wind turbine generators using superconducting coils and bulks

Superconducting wind turbine generators having arc-shaped bulk superconductors as a magnetic shielding component in the rotor, superconducting coils for DC field generation and armature windings have been studied. Three-dimensional finite element analysis of electromagnetic characteristics of the machines has been carried out to design the machines and to evaluate their fundamental performance.

Wind turbine generators using superconducting coils and bulks

Superconducting wind turbine generators having arc-shaped bulk superconductors as a magnetic shielding component in the rotor, superconducting coils for DC field generation and armature windings have been studied. Three-dimensional finite element analysis of electromagnetic characteristics of the machines has been carried out to design the machines and to evaluate their fundamental performance.

Design and characteristic analysis of 10 MW class superconducting wind turbine generators with different types of stator and rotor configurations

Wind power generation facilities have been installed in the world. Recently offshore wind energy attracts greater attention, and development of wind turbine generators of higher power rating becomes more important. Superconducting technologies is expected to be applied to over 10 MW class generators. We have studied 10 MW class large wind turbine generators using superconducting technologies. The paper presents fundamental structures of large-scale wind turbine generators, paying attention to the reduction of superconducting wire length, and generator size and weight. Some design results of 10 MW wind turbine generators are shown and compared.

Design study of linear synchronous motors using superconducting coils and bulks

Superconductors have advantages of zero resistance, generation of high magnetic fields, large current density. Practical high-temperature superconductors are now available for fabricating coils and bulk magnets. These materials have a variety of potential applications in power industry. In this paper, we propose conceptual design of new linear synchronous motors using high-temperature superconducting coils and bulks, and perform three-dimensional finite-element analyses of electromagnetic characteristics. A DC field magnet is designed using superconducting coils and bulks taking into account the characteristics of high-temperature superconducting materials. The thrust characteristics of the linear motors were analyzed.

Magnetic Shielding Characteristics of Multiple Bulk Superconductors for Higher Field Applications

High performance (RE) BaCuO bulk superconductors are now available and can be used as a strong magnet or a good magnetic shield. There are a variety of potential magnetic shielding applications using bulks. Magnetic shielding characteristics and size of bulk superconductors are the key issues to realize these applications. In this paper, magnetic shielding experiments using GdBaCuO bulk superconductors at 77 K are reported. Multiple bulk super conductors are arrayed and stacked in layers to obtain a large magnetic shield. We successfully obtained a uniform magnetic shielding area with properly arranged three layers of tiled bulks at 0.1 T, 77 K. We also discuss the magnetic shielding characteristics for different external magnetic fields strengths.

Vibrational characteristics of a superconducting magnetic bearing employed for a prototype polarization modulator

We present the vibrational characteristics of a levitating rotor in a superconducting magnetic bearing (SMB) system operating at below 10 K. We develop a polarization modulator that requires a continuously rotating optical element, called half-wave plate (HWP), for a cosmic microwave background polarization experiment. The HWP has to operate at the temperature below 10 K, and thus an SMB provides a smooth rotation of the HWP at the cryogenic temperature of about 10 K with minimal heat dissipation. In order to understand the potential interference to the cosmological observations due to the vibration of the HWP, it is essential to characterize the vibrational properties of the levitating rotor of the SMB. We constructed a prototype model that consists of an SMB with an array of high temperature superconductors, YBCO, and a permanent magnet ring, NdFeB. The rotor position is monitored by a laser displacement gauge, and a cryogenic Hall sensor via the magnetic field. In this presentation, we present the measurement results of the vibration characteristics using our prototype SMB system. We characterize the vibrational properties as the spring constant and the damping, and discuss the projected performance of this technology toward the use in future space missions.

Design and development of a polarization modulator unit based on a continuous rotating half-wave plate for LiteBIRD

We present our design and development of a polarization modulator unit (PMU) for LiteBIRD space mission. LiteBIRD is a next generation cosmic microwave background (CMB) polarization satellite to measure the primordial B-mode. The science goal of LiteBIRD is to measure the tensor-to-scalar ratio with the sensitivity of δr < 10-3. The baseline design of LiteBIRD is to employ the PMU based on a continuous rotating half-wave plate (HWP) at a telescope aperture with a diameter of 400 mm. It is an essential for LiteBIRD to achieve the science goal because it significantly reduces detector noise and systematic uncertainties. The LiteBIRD PMU consists of a multi-layered sapphire as a broadband achromatic HWP and a mechanism to continuously rotate it at 88 rpm. The whole system is maintained at below 10K to minimize the thermal emission from the HWP. In this paper, we discuss the current development status of the broadband achromatic HWP and the cryogenic rotation mechanism.

Optimal Design of a Superconducting Motor for Electric-drive Aeropropulsion Based on Finite-Element Analysis and Genetic Algorithm

Electric-drive Aeropropulsion is one of the key technologies in design of future aircrafts because the electric motor drive has high efficiency and the this would reduce operational cost and pollutant emission. This paper discusses the optimization of electromagnetic design of superconducting motors. Finite element analysis, multi-objective genetic algorithm and analytical equations are applied in the optimization. Power density, power loss including AC loss of superconducting materials, and torque ripple are considered in the objective function. The results of optimization suggest that the application of superconducting motor is feasible for electric-drive aeropropulsion with power density higher than 16.4 kW/kg.