• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.884-885
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• 2011

A great deal of external magnetic variation is required to demagnetize a magnetic material. In order to analyze a demagnetization model, hysteresis is employed and the best numerical analysis technique so far, regarding hysteresis, is Preisach model. In general, Preisach model, however, bears the instability problem with respect to convergence and hence in this paper, a method adopting M-B variables is proposed to solve the problem. In addition, comparison is made between the experimental MTF equipment and the hysteresis modeling technique for the purpose of developing an effective demagnetization protocol.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.8
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• pp.1502-1509
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• 2011

This Paper presents characteristic analysis in terms of interior permanent magnet synchronous motor for electric vehicle propulsion using numerical analysis. Torque ripple analysis, thermal analysis, demagnetization analysis of permanent magnet and mechanical stress analysis with variable operating condition are presented. According to these characteristic analysis, both the performance of motor and possible problems during the operation are examined thoroughly in advance.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.863_864
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• 2009

Design and drive characteristics of SR drive for hydraulic pump system using passive converter is presented in this paper. In oder to get the high performance, a simple passive circuit is added in the front-end of a conventional asymmetric converter, which consists of three diodes and one capacitor. This passive converter has the high demagnetization voltage, to reduce the demagnetization time. Futhermore optimal turn-off angle for the proposed passive converter is proposed. According to motor speed and current, an optimal turn-off angle can be achieved by look-up table to reduce torque ripple. The characteristic of proposed hydraulic pump system using passive converter is verified by simulation and experimental results.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.8
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• pp.1519-1525
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• 2009

This paper presents a novel passive converter for single phase SRM. The proposed passive converter has additional passive power circuit which is consisted by three diodes and one capacitor in the front-end of conventional asymmetric converter to supply a high negative bias during demagnetization. The high negative bias can reduce the demagnetization time and negative torque from tail current in single phase SRM. So, It can extend positive torque region by the extended turn-off position. In this paper, the structure and operating modes of a novel passive converter are introduced with mathematical model. The proposed single phase SRM using passive converter is verified by the computer simulation and experimental results.

• 전기의세계
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• v.22 no.1
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• pp.9-19
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• 1973

This paper is for the supplementary studies of the theoretical treaties on the machine dynamics of the amplidyne generator under the influencies of the armature reaction. The author has already shown the time-domain expression of the dynamic relations of the machine with balanced control winding, under this operating condition. In this paper, analytical and experimental studies of a test machine are intended to supplement the theories derived in the previous work, entitled "On the dynamics and the demagnetization effect of the amplidyne generator with auxiliary feedback compensating winding". FACOM 230 digital computer is incorporated for processing of a series of experimental data. The machine dynamics are then numerically analyzed with the aid of the computer. The virtual machine responses to stepwise inputs are compared with the computer output to confirm the influence of the armature reaction effect on to the machine dynamics. dynamics.

• Proceedings of the KIEE Conference
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• 2004.04a
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• pp.74-76
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• 2004

This paper deals with the analytical method to calculate the high temperature demagnetization characteristics of a high-speed machine with diametrically magnetized permanent magnet rotor. The equivalent magnetic circuit model is used to analyze the magnet operating point on high temperature condition. Agreements have been obtained between the results of the analytical model and finite-element analysis on prototype high-speed motors.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.7
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• pp.337-345
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• 2006

This paper proposes a high speed SRM drive system for blower application with a new 4-level inverter and precise excitation position generator. For a high speed blower, a proper inverter and control method are proposed and the output characteristics are analyzed. In order to get a fast build-up and demagnetization of excitation current, a 4-level inverter system is proposed. The proposed 4-level inverter has additional charge capacitor, power switch and diode in the conventional asymmetric converter. The charged high voltage is supplied to the phase winding for fast current build-up, and demagnetization current is charged to additional capacitor of the 4-level inverter. In addition, a precise excitation position generator can reduce turn-on and turn-off angle error according to sampling period of digital control system. The proposed high speed SRM drive system is verified by computer simulation and experimental results.

• Journal of the Korean Society for Railway
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• v.12 no.3
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• pp.335-341
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• 2009

To predict efficiency of interior permanent magnet synchronous motor (IPMSM) for traction motor and to cope with the risk of demagnetization in the permanent magnets, accurate iron loss analysis and understanding of the characteristic of the iron loss are very important at motor design stage. In this paper, we present the method to estimate the iron loss for the IPMSM considering the driving conditions such as both field weakening control and maximum torque per ampere control.

• Proceedings of the KIEE Conference
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• summer
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• pp.905-907
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• 2004

This paper deals with the PM performance evaluations in a variable flux memory motor (VFMM) using a coupled finite element method (FEM) and Preisach modeling, which is presented to analyze the magnetic characteristics of permanent magnets. The focus of this paper is the operation characteristics evaluation relative to magnetizing direction and quantity of permanent magnets on re-, demagnetization condition in a variable flux memory motor(VFMM)

• Journal of Power Electronics
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• v.10 no.4
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• pp.388-395
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• 2010

An active boost converter for a single phase SRM using series-parallel connected capacitors is proposed in this paper. The proposed active boost converter has two diodes and one power switch with an anti-parallel diode and one additional boost capacitor. The additional boost capacitor could be series or parallel connected to the dc-link capacitor to produce proper excitation and demagnetization voltage. The proposed active boost converter can easily achieve a fast excitation and demagnetization from the capacitor connection. In this paper, series and parallel connected converters are reviewed, and the detailed operating modes as well as the voltage characteristics of the proposed converter are analyzed. The simulation and experimental results shows the effectiveness of the proposed active boost converter.