Dong-Woo Kang

A Study on the Optimal Rotor Design of LSPM Considering the Starting Torque and Efficiency

This paper presents the optimal rotor design method in a single-phase line-start permanent magnet motor (LSPM) considering the starting torque and efficiency. To consider nonlinear characteristics, the design process is comprised of the FEM and analytical method. During this study, permanent-magnets and cage bars were designed using the magnetic equivalent circuit method and the barriers that control all magnetic flux were designed using the FEM, and the tradeoff of starting torque and efficiency is controlled by weight function in Taguchi method simulation. Finally, the performance of the optimal model is compared with those of conventional models.

Optimal PM Design of PMA-SynRM for Wide Constant-Power Operation and Torque Ripple Reduction

This paper presents the design process of permanent magnets to enable a wide range of constant-power operation and reduce the torque ripple by using analytical and numerical methods in PMA-SynRM. For a wide range of constant-power operation, the minimum d-axis flux-linkage of the permanent magnet is designed to be close to zero. Moreover, the unbalanced flux density in each segment is adjusted by changing the size of each permanent magnet to reduce the torque ripple. Finally, control simulations and experiments will be conducted to prove the validity of the suggested process.

Method of Current Compensation for Reducing Error of Holding Torque of Permanent-Magnet Spherical Wheel Motor

A permanent magnet spherical wheel motor, which consists of magnets on rotor and coils on spherical stator, is able to operate on 3-D space as using magnetic alignment torque generated from between coils and magnets. Especially the shaft can be tilted stably by optimized coil position on stator. Because, however, the spherical wheel motor has feature of 3-D structure as relative position between coils and magnets, stable holding torque for rotor position should be analyzed as function of the tilt degree of a shaft. The characteristic of stable holding torque can be changed nonlinearly by the alpha and beta degrees of a shaft. Therefore, when reference current is commanded at coils, the shaft cannot be tilted to the reference position exactly for the nonlinear characteristic. In this paper, for improving the nonlinear phenomenon of holding torque, the authors research and improve a current compensation function to increase stable operating range. Also, the compensation function was estimated by using torque ripple computed from torque simulation.

Torque Calculation Method of a Permanent Magnet Spherical Motor

This paper presents the torque calculation method of a permanent magnet spherical motor. To calculate using the finite element method (FEM), three-dimensional (3D) FEM must be used. However, since the method requires excessive time and memory, an easier torque calculation method is hereby presented. In the proposed method, it is very important to obtain the approximation function of the torque profile curve. We present the approximation method of the torque profile curve and show that the torque calculation result can approximate the torque obtained by 3-D FEM.

Robust Zero Power Levitation Control of Quadruple Hybrid EMS System

This paper presents the improved zero power levitation control algorithm for a quadruple hybrid EMS (Electromagnetic Suspension) system. Quadruple hybrid EMS system is a united form of four hybrid EMS systems one on each corner coupled with a metal plate. Technical issue in controlling a quadruple hybrid EMS system is the permanent magnets equilibrium point deviation caused by design tolerance which eventually leads to a limited zero power levitation control that only satisfies the zero power levitation in one or two hybrid EMS system among the four hybrid EMS system. In order to satisfy a complete zero power levitation control of the quadruple hybrid EMS system, the proposed method presented in this paper adds a compensating algorithm which adjusts the gap reference of each individual axe. Later, this paper proves the stability and effectiveness of the proposed control algorithm via experiment and disturbance test.

Research on the Correlation of Control Malfunction with Induced Voltage of Control Signal Line According to Voltage Change of a Power Line

This induced voltage measurement test and electromagnetic field simulation are related to the possibility of control signal malfunction by power line. Through an experiment, this research analyzed whether the voltage causing control malfunction according to the on/off status of power permitted to power line was induced to control signal line. Also, the research calculated the voltage induced to control signal line and examined the phenomenon by conducting an electro-magnetic field-specific simulation through the finite element method for the cable model used in the experiment.

Characteristics Analysis of Single Phase Induction Motor via Equivalent Circuit Method and Considering Saturation Factor

This paper presents a motor characteristics analysis method using an equivalent circuit. Motor characteristics analysis via equivalent circuit is very important for designing a high efficiency single phase induction motor. The accuracy of the motor characteristics depends on the accuracy of the parameters, especially saturation factor, which determines the cyclical relationship in the analysis process. Therefore, using the proposed method, the saturation factor was calculated using the iteration routine and numerical technique. The proposed method was verified by comparing the finite element method results and the dynamo test results of manufactured prototype model.

Transient analysis by using current vector of three dimensional space for multi-degree of freedom permanent-magnet motor

The multi-degree of freedom surfaced permanent-magnet motor (Multi-D.O.F. SPM) researched in this paper has characteristic of rotor tilt. Generally electromagnetic field of an electric rotating machine is analyzed by using the 2-D finite element method, because the electromagnetic features show same phenomena in the rotational axis direction. However the Multi- D.O.F. SPM should be analyzed by using 3-D finite element method for spherical structure of stator. Therefore this paper proposes useful method of 3-D electromagnetic field computation. Finally the results are verified by experimentation.

Compensated phase method of current for reducing torque ripple of multi-degree of freedom surfaced permanent-magnet motor

In this paper, the torque characteristics of multi degree of freedom surfaced permanent-magnet motor (multi-D.O.F. SPM) are introduced. The multi-D.O.F. SPM can rotate a shaft while the rotor tilts to one side [1]. To decrease the torque ripple, the locus of summed wave forms of motor driving current have to be in an ellipse. Because the axis of electro motive force is generated by many numbers of currents as considering rotor position, the currents have different phase while the rotor is tilting. Therefore the phase of each current is defined as function of rotor position as using compensated phase method in this paper. The modified current is verified by comparison of analytic simulation results to experimentation results.