So-Young Sung

Design Considerations of EM-PM Hybrid Levitation and Propulsion Device for Magnetically Levitated Vehicle

This paper deals with the design considerations of electromagnet/permanent magnet (EM-PM) hybrid levitation and propulsion device for magnetically levitated (maglev) vehicle. The machine requires PMs with high coercive force in order to levitate the vehicle by only PMs, and propulsion force is supplied by long-stator linear synchronous motor (LSM). The advantages of this configuration are an increasing levitation airgap length and decreasing total weight of the vehicle, because of the zero-power levitation control. Several design considerations such as machine structure, manufacturing, and control strategy are described. Moreover, this paper proposes the novel translator structure with segmented U-shape magnets for easy manufacturing. In order to verify the design scheme and feasibility of control strategy, dynamic test set is implemented and tested.

Improved Analytical Modeling of Axial Flux Machine With a Double-Sided Permanent Magnet Rotor and Slotless Stator Based on an Analytical Method

This paper presents the results of an experimental verification and electromagnetic field analysis for an axial flux permanent magnet (PM) synchronous generator (AFPMSG) with a double-sided PM rotor and slotless stator windings based on analytical field computation to offer improved analytical modeling method. An analytical approach to analyze the magnetic field distribution and estimate the equivalent circuit parameters is presented that dramatically reduces analysis time while maintaining high reliability. Since the flux leakage phenomenon is dominant in the inner and outer radii of this type of AFPMSG, it is specifically considered. In addition, an actual device was fabricated on the basis of one of the analysis models, and used to experimentally verify all of the analysis results.

Dynamic and Experimental Performance of Linear-Switched Reluctance Machine With Inductance Variation According to Airgap Length

This paper deals with the dynamic and experimental performance of a linear-switched reluctance machine with inductance variation according to airgap length. First, analytical solutions for flux density due to mover winding currents are derived for the case when the mover is located at an aligned and unaligned position. And then, using the inductance at an aligned and unaligned position obtained from 2-D analytical solutions and Fourier series expansion proposed in this paper, we predict the inductance profile of the linear-switched reluctance machine (LSRM) analytically. Finally, with the experiment of manufactured LSRM, the validity of the characteristic equations is demonstrated, and the operating experiment is performed by manufacturing the operating circuit for the experiment of the operating characteristic according to the airgap length.

Design and Characteristic Analysis on the Short-Stator Linear Synchronous Motor for High-Speed Maglev Propulsion

The design and characteristic analysis on the linear synchronous motor (LSM) for high-speed maglev propulsion is discussed. We describe the techniques for the design, analysis, construction, and experiment of a prototype propulsion system with short-stator LSM. On the basis of a 2-D analytical field analysis, this paper predicts the magnetic field due to dc excitation and three-phase winding current, the back-EMF, and the electromagnetic torque characteristics. The results are validated extensively by comparison with finite-element analysis and experiment. The propulsion performance was tested by using a high-speed rotary type test wheel with linear peripheral speed up to 283 km/h.

Comparative Investigation on Integrated System of Permanent Magnet Synchronous Generator and Power Converter Based on Machine Topology for Small-Scale Wind Power Application

This paper presents the comparative analysis and test results of permanent magnet (PM) synchronous generators based on machine topology for small-scale wind power application. For reasonable comparison, various design considerations, such as flux direction, rotor position, slot existence and PM materials, are dealt with under specific machine size limitation. Among the analysis models, five machines are manufactured for experimental verification, and the generators are integrated with AC-DC-DC converter to convert originally generated AC power to DC power. With our constructed experimental set, the electromagnetic characteristics based on measured current, and their performance are comparatively investigated under constant output voltage control condition.

Operating Range Evaluation of Double-Side Permanent Magnet Synchronous Motor/Generator for Flywheel Energy Storage System

This paper deals with the operating rage evaluation on double-side permanent magnet synchronous motor/generator (DPMSM/G) for flywheel energy storage system (FESS). The motor/generators used in FESS have wide operating range due to its charge/discharge mechanism. The motor/generators should be operated to satisfy not only the required electric power but also structural stability in operating range of FESS. To evaluate the operating range of FESS, this paper presents the approach on the electromagnetic and mechanic characteristic analysis using a developed DPMSM/G. As the electromagnetic characteristic, the motoring and generating characteristic analysis are performed by circuit parameter estimation. In addition, as the mechanical characteristic, the rotor dynamics analysis of the flywheel rotor is performed. Finally, the operating performance and analysis result will be confirmed by experiment.

Improved Analytical Modeling of a Ellipse Shape Permanent Magnet Rotor in Ultra-High-Speed Brushless DC motor for the Reduction of Torque Ripple

This paper deals with the ellipse permanent magnet machines for the minimization of torque ripple based on electromagnetic field theory. On the basis of a magnetic vector potential and a two dimensional (2-D) polar system, analytical solutions for flux density due to permanent magnet (PM) and current are obtained. In particular, the analytical solutions for mathematical expressions of magnets with different circumferential thicknesses can be solved introducing improved magnetization modeling techniques. The analytical results are validated extensively be nonlinear finite element solutions, a reduction of torque ripple can be achieved.

Thrust Analysis and Experiments on Low-Speed Single-Sided Linear Induction Motor

When the characteristics of a linear induction motor (LIM) are analyzed using finite element analysis (FEA), it is desirable to set the voltage source as an input. If the voltage source is set as an input in FEA, the leakage inductance and primary resistance of the equivalent circuit must be entered by direct calculation, and the magnetizing inductance and secondary reaction effects are directly considered in FEA. Exact calculation is necessary because the primary winding resistance and leakage inductance directly entered will have a significant effect on the LIM output. Therefore, in this study, we accurately calculated the primary leakage inductance and analyzed the resulting LIM characteristics. We calculated the leakage inductance using an analytical equation and FEA, and we confirmed the accuracy by comparing the results with the value experimentally calculated using a manufactured model. We also analyzed the instrument performance and thrust of the LIM as a function of the difference in the leakage inductance. Finally, we present the conclusions on the precise analysis based on the calculation of the leakage inductance.

Torque Analysis of Magnetic Spur Gear with Radial Magnetized Permanent Magnets based on Analytical Method

Abstract - This paper deals with torque analysis of magnetic spur gear with radial magnetized permanent magnets based on analytical method. The analysis is implemented in three parts: First, on the basis of magnetic vector potential and a two-dimensional (2D) polar-coordinate system, the magnetic field solution due to permanent magnet of source gear are obtained. And by using derived magnetic field solutions, the analytical solutions for external magnetic field distribution which affects load gear are obtained. Second, by using coordinate conversion, external magnetic field which is on the primary coordinate system is converted to the secondary coordinate system. Finally, the load gear is reduced to equivalent current densities, and the torque is computed on these currents in the external field of the source magnet. These analytical results are validated by comparing with the 2-D finite element analysis (FEA).Key Words : Magnetic spur gear, Coordinate conversion, Analytical solutions, FEA†Corresponding Author : Dept. of Electrical Engineering,Chungnam National University, Korea.E-mail: choi_jy@cnu.ac.kr* Dept. of Electrical Engineering, Chungnam National University,Korea.** Korea Research Institute of Ships & Ocean Engineering, Korea.Received : January 30, 2015; Accepted : March 22, 2015그림 1 기어의 구조 : (a) 기계적인 스퍼 기어 (b) 자기 스퍼 기어Fig. 1 Structure of : (a) mechanical spur gear (b) magnetic spur gear

Improved thrust calculations of active magnetic bearings considering fringing flux

A methodology for deriving fringing permeance in axisymmetric devices such as active thrust magnetic bearings (ATMBs) is presented. The methodology is used to develop an improved equivalent magnetic circuit (EMC) for ATMBs, which considers the fringing effect. This EMC was used to characterize the force between the housing and mover and the dependence of thrust and inductance on the air gap and input current, respectively. These characteristics were validated by comparison with those obtained by the finite element method and in experiments.