2PO8-10 The Characteristic Analysis of the Flux Damper located in High-T_c Superconducting Synchronous Motor Through 3-Dimensional Magnetic Field Analysis Using F.E.M

Myung-Kon Song 1, Sang-Jin Lee 2, and Tae-Kuk Ko 1. 1 Dept. of EE. in Yonsei Univ., 120-749, 134 Shinchon-Dong, Seodaemun-GU, Seoul, Republic of Korea. 2 Dept. of EE. in Uiduk Univ., 780-713, Fangdong, Kyongju, Korea.

Presenting Author: S.J. Lee

This paper deals with the characteristic analysis of the flux damper with respect to the load and the size of flux damper itself in the high-T_c superconducting synchronous motor. First, the electrical equivalent circuit of high-T_c superconducting motor with the flux damper was derived and computer simulation was performed with the equivalent circuit using F.D.M. and Second, the 3-dimensional magnetic distribution in high-T_c superconducting synchronous motor was solved by F.E.M. The simulation results show that the transient state lasts for about 2 sec. and the flux damper shields the time varying field up to 10 percent.

2PO8-11 Hysteresis and Reluctance Electric Machines on the Basis of the Bulk HTS Elements. Recent Results and Future Development

K.L. Kovalev 1, K.V. Ilushin 1, S.M.-A. Koneev 1, L.K. Kovalev 1, V.T. Penkin 1, W. Gawalek 2, and B. Oswald 3. 1 Moscow State Aviation Institute (Technical University), Moscow, Russia. 2 Institut fuer Physikaliche Hochtechnologie, Jena, Germany. 3 OSWALD Elektromotoren GmbH, Miltenberg, Germany.

Presenting Author: K.L. Kovalev

Novel types of electric HTS motors with the rotor containing bulk YBCO elements are presented. Different schematics of hysteresis, reluctance and trapped field HTS motors are discussed. The two-dimensional mathematical models describing the processes in such types of HTS machines were developed on the basis of the theoretical analysis of the electrodynamic and hysteresis processes in the multi-domain and single-domain YBCO ceramic samples. The test results of the series of hysteresis, reluctance and trapped field motors with output power rating 0.1-40kW and current frequency 50Hz and 400Hz are given. These results show that in the media of liquid nitrogen the specific output power per one weight unit is 4-5 time better then for conventional electric machines. HTS hysteresis and reluctance motors worked for several hours and had stable mechanical characteristics. Comparison of the theoretical and experimental characteristics of the developed hysteresis and reluctance HTS motors show that they are in good agreement. The test results for liquid nitrogen cryogenic pump system with hysteresis 500W HTS motor are given. The design of a new reluctance HTS motor operating in the media of liquid nitrogen with output power 500kW and power factor more then 0.8 is described. Future applications of new types of HTS motors for airspace and on-land transport systems are discussed.

2PO8-13 Analysis of Dynamic Response for HTS Maglev Vehicle Model

Yong Zhang and Shangang Xu, Institute of Electrical Engineering Chinese Academy of Sciences, Beijing 100080 P.R.China and Texas Center for Superconductivity, University of Houston, Houston, TX 77204.

Presenting Author: Y. Zhang

Stable levitation force can be obtained with YBCO HTS bulk material and NdFeB permanent magnets acting on each other. To explore the possible application of HTS bulk material in a Maglev vehicle, we have developed an HTS Maglev vehicle model. Random vibration analysis and experiments are carried out on the vehicle model. All of the analysis and experimental results show that the amplitude of vibration in the degrees of freedom of lateral direction and side roll are larger than others. To improve the performance of the vehicle in this regard, the author advances some steps to increase the stability of the Maglev vehicle model in the direction of lateral and side roll.

2PO8-14 Static Structure Analysis of Vertical Rotational System With Hybrid Superconducting Magnetic Bearings

Hong Ye 1,2, Pingchou Xia 1, and Liangzhen Lin 1. 1 Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100080, China. 2 Texas Center for Superconductivity at the University of Houston, Houston, TX 77204-5932.

Presenting Author: H. Ye

A small restoring force of Superconducting Magnetic Bearings (SMB) may be used to balance larger unstable property brought by Permanent Magnetic (PM) bearings. To illustrate this principle, a prototype of a vertical rotational system consisting of a SMB and a passive PM bearing is designed and made. An SMB is put at the bottom of the vertical rotor to provide stable force in both the axial and radial directions. The passive PM bearing is assembled on the top of the rotor to provide stable levitation force in the axial direction. The static structure of this vertical rotational system with SMB and PM bearings is analyzed.

2PO8-15 The Design and Characteristic Analysis of Active Quench Protection System for Superconducting Magnet

Yong Chu, Ho Min Kim, and Tae Kuk Ko, Dept. of Electrical Eng., Yonsei Univ., 120-749 134 Shinchon-Dong Sedaemu-Gu Seoul, South Korea

Presenting Author: T.K. Ko

The detection of the normal zones in the coil winding and the initiation of the proper dump sequence have been one of the most important areas in the superconducting magnet technology. The active protection scheme is also needed for protection of the high-T_c superconducting magnet. In this paper, the theoretical process to derive the optimal dump sequence has been investigated in the magnetically coupled adiabatic magnet system. The magnet terminal voltage, maximum temperature in the quench initiation point and resistance rise in the winding are calculated numerically with respect to various input variables such as operation current, dump resistance, etc. The experimental system is comprised of 3-nested solenoidal coils, data aquisition device, external circuit breakers and dump resistor. The quench behavior of the magnet (e.g., the temperature profile and the voltage signals) was measured as a function of operation current, dump resistance, etc. From these results, the theoretical predictions were found to coincide with the experimental observations.

2PO8-16 Stiffness and Damping of an Axial Superconducting Magnetic Bearing

R. de Andrade, Jr. 1, A. Ripper 2, D.F.B. David 3, and R. Nicolsky 4. 1 DEE/EE Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, 21945-970, Brazil. 2 PEM/COPPE Universidade Federal do Rio de Janeiro Rio de Janeiro, RJ, 21945-970, Brazil. 3 TEM, Universidade Federal Fluminense, Niteroi, RJ, 24210-240, Brazil. 4 Instituto de Física, Universidade Federal do Rio de Janeiro Rio de Janeiro 21945-970, Brazil.

Presenting Author: R. de Andrade, Jr.

An axial superconducting magnetic bearing with radial symmetry has been designed using two NdFeB permanent magnets levitating on a set of seven superconducting monoliths of YBCO, prepared by top-seeded-melt-texturing technique. The permanent magnet set consists of a disc shaped magnet and a ring shaped one assembled concentrically and with anti-parallel dipoles. The superconductor set consists of close-packed disc shaped monoliths thermally anchored on a Cu block. The air gap between the magnets and the superconductors for different field cooling distances has been measured depending on the levitating mass and the use of a back yoke in the permanent magnet ensemble. The air gap exhibits an increase with cooling distance asymptotically to the zero-field-cooling condition. The elastic constants for axial and radial displacement has been obtained from frequency and decay rate of the free vibration curves, of the mass element attached to the bearing, taken for different air gaps. The resulting data may indicate that the bearing stiffness and the respective damping coefficient are dependent on cooling distance. The stiffness exhibits no significant dependence on the oscillation amplitude conversely to the damping coefficient that exhibits a strong dependence on it.

2PO8-17 Numerical Optimization of the Magnetic Field of A New Hybrid Superconducting Magnetic Bearing Flywheel

J.R. Fang 1, L.G. Yan 1, L.Z. Lin 1, and P.C. Xia 2. 1 The Division of Applied Superconductivity, Institute of Electrical Engineering, Chinese Academy of Sciences, P.O. Box 2703, Beijing 100080 China. 2 The Division of Magnet Technology, Institute of Electrical Engineering, Chinese Academy of Sciences, P.O. Box 2703, Beijing 100080 China.

Presenting Author: J.R. Fang

In order to deal with low stiffness and dampness, the uncertainty of working place, a new 1kWh hybrid superconducting magnetic bearing (HSMB) flywheel including active magnetic bearings (AMB) has been presented. In this paper, by using commercial finite element method (FEM) software, the thin plate eddy current code is applied to analyze the magnetic field of HSMB flywheel, and evaluate its levitation force. Also we use a two dimensional FEM to optimizate the parameters of radial AMB. It is indicated that the load capacity and stiffness depends largely on the magnetic field configuration.

2PO8-18 A New Flywheel Energy Storage System with Hybrid Superconducting Magnetic Bearings

J.R. Fang 1, L.Z. Lin 1, L.G. Yan 1, and P.C. Xia 2. 1 The Division of Applied Superconductivity, Institute of Electrical Engineering, Chinese Academy of Sciences, P.O. Box 2703, Beijing 100080 China. 2 The Division of Magnet Technology, Institute of Electrical Engineering, Chinese Academy of Sciences, P.O. Box 2703, Beijing 100080 China.

Presenting Author: J.R. Fang

Since the discovery of high temperature superconductor (HTS) YBCO in 1987, HTS coupled with permanent magnets have been applied to construct superconducting magnetic bearings which can be utilized in many engineering fields such as flywheel energy system (FES), high-speed centrifugal machine. However, there are many problems needed to be resolved, such as the uncertainty of low stiffness and dampness, working place, flux creep and flow. In this paper, a new hybrid permanent active magnetic bearing (HSMB) has been presented. In this design, we constructed a prototype of 1kWh FES with HSMB. A passive permanent bearings is added to provide a levitation force so as to suspend more weight flywheel; on the other hand, an active magnetic bearing is joined in radial direction to improve stiffness and dampness of FES.

2PO8-19 Superconducting Flywheel Development for Upgrading Power Quality

I. Vajda 1, T. Porjesz 2, A. Szalay 3, N. Gobl 3, and J. Lukacs 1. 1 Department of Electrical Machines and Drives, Technical University of Budapest, Egry József utca 18, H-1111 Budapest, Hungary. 2 Department of General Physics, Eötvös University, Budapest, Hungary. 3 S–Metalltech, Ltd, Budapest, Hungary.

Presenting Author: I. Vajda

The quality of the supplied electrical energy is a vital issue for the electrical utilities to be competitive in satisfying the consumers’ needs. Voltage dips may cause plant outages resulting in very high costs for the sensitive consumers. Superconducting energy storage devices can offer economically beneficial solutions to power quality problems when compared to the financial loss caused by power disturbances. The case of the superconducting flywheel is discussed in terms of a feasibility study. The technical viability as well as the benefits of the application of HTS flywheels for the upgrading of power quality of power systems is shown.

For the checking of the technical requirements an experimental HTS flywheel has been designed and constructed. The calculated stored energy of the flywheel at 10,000 rpm is 2.48 kJ. The levitation force is generated by the HTS/PM interaction. We have developed the computer code "WinTer" to calculate the levitation characteristics.

One particular feature of the design is the integration of the flywheel rotor with the motor/generator unit. The rotor incorporates an aluminium body in the form of a thin-walled hollow cylinder driven by the rotating magnetic field generated by the three-phase stator winding. A special fixation mechanism has been developed to set the appropriate position of the levitator. High speed of rotation is achieved by evacuating the chamber for the rotating part of the flywheel. The conclusions of the feasibility study as well as the calculation and test results are presented.