• 조명전기설비학회논문지
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• 제28권1호
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• pp.57-68
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• 2014

This paper propose a development of squirrel-cage induction motor(IM) for 5-phase 1.5kW, 220V, 60Hz in order to study a polyphase ac machinery that keep hold of advantages more than traditional three-phase a IM, such as reducing a amplitude of torque pulsation, decreasing electric noises, and increasing the reliability. Designed methods of the motor use a development tools with Maxwell 2D and Simplorer program. There are designed drawing of manufactured frames of the IM. amplitude and waveform of the generated electromotive force, FFT analysis of harmonics within output voltages and current, and reviewing a experiment results are shown by variable output. We are presenting a design and manufacture methods for the 5-phase squirrel-cage IM.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2000년도 전력전자학술대회 논문집
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• pp.228-231
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• 2000

When the vector control which does not need a speed signal from a mechanical speed sensor it is possible to reduce the cost of the control equipment and to improve the control performance in many industrial application. In this paper describes a rotor speed estimate method of induction motor based on the theory of counter EMF MRAS. This method eliminated the pure integrator. and we can be expected to rapid responsibility of the speed identification, Therefore we improve the initial condition of the integrator and drift problem. The stability of speed estimator is proved on the basis of hyperstability theory. In order to confirm the performance of the proposed system Simulation and experiment is performed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 B
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• pp.1144-1146
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• 2001

In this paper, describes a rotor speed identification method of induction motor based on the theory of counter EMF MRAS. This method eliminated the pure integrator and we can be expected to rapid responsibility of the speed identification. Therefore, we may improve the initial condition of the integrator and drift problem. The stability of speed estimator is proved on the basis of hyperstability theory. In order to confirm the performance of the proposed system, simulation and experiment is performed.

• 제어로봇시스템학회논문지
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• 제5권7호
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• pp.862-867
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• 1999

In general, the realization of high performance brushless permanent magnet motors which are widely used in servo drive is focused on the linear control for ripple-free torque. This is also the main problem that should be solved in all AC motors including induction motor to achieve high performance control, and recent papers deal with this problem. In this paper, the novel optimal excitation scheme of brushless permanent magnet motor producing loss-minimized ripple-free torque based on the d-q-0 reference frame is presented including 3 phase unbalanced condition. The optimized phase current waveforms that are obtained by the proposed method can be a reference values and the motor winding currents are forced to track it by delta modulation technique. As a results, it can be shown that the proposed work can minimize the torque ripple by the optimal excitation current for brushless permanent magnet motor with any arbitrary phase back EMF waveform. Simulation and experimental results prove the validity and practical applications of the proposed control scheme.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제5B권4호
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• pp.358-365
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• 2005

In induction machine drive without a speed sensor, the estimation of the motor flux and speed often becomes deteriorated at low speeds with low back EMF. Our analysis shows that, in addition to the state resistance variation, the estimated value of field orientation angle is often corrupted by accumulative errors from the integration of voltage variables at motor terminals that have low signal/noise ratio at low frequencies. A repetitive loop path of integration in the feedback can amplify this type of error, thus speeding up the degradation process. The control system runs into information starvation due to the loss of correct field orientation. The machine's spiral vectors are controlled only in a reduced dimension in this situation. A novel control scheme is developed to improve the control performance of motor's current, torque and speed at low frequencies. The scheme gains a full-dimensional vector control and is less sensitive to the combined effect of the error sources at the low frequencies. Experimental tests demonstrate promising performances are achievable even below 0.5 Hz.

• Journal of Magnetics
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• 제18권2호
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• pp.105-110
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• 2013

The design model and key parameters of the material design for the control of induced magnetic flux at the near-field and efficient power transfer in a modified wireless power transfer (WPT) system with a large air gap of wireless electric vehicles were investigated through analytical simulations for magnetic vector and time-domain transient analysis. Higher saturation magnetic core with low core loss induced a stronger vertical magnetic field by the W-type primary coil in the WPT system with a gap of 20 cm at 20 kHz, which is shown from the vector potentials of the magnetic induction. The transient analysis shows that the higher magnetic fluxes through the pick-up cores lead to a linear increment of the alternating voltage with a sinusoidal waveform in the non-contact energy transfer system.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 전력전자학술대회 논문집
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• pp.409-412
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• 2001

When the vector control, which does not need a speed signal from a mechanical speed sensor, it is possible to reduce the cost of the control equipment and to improve the control performance in many industrial application. In this paper, describes a rotor speed estimate method of induction motor based on the theory of counter EMF MRAS. This method eliminated the pure integrator. and we can be expected to rapid responsibility of the speed Identification. Therefore, we improve the initial condition of the integrator and drift problem. The stability of speed estimator is proved on the basis of hyperstability theory. In order to confirm the performance of the proposed system. Simulation and experiment is performed.

• 한국산업보건학회지
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• 제32권4호
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• pp.381-392
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• 2022

Objectives: Objective of this study is to review briefly exposure characteristics, monitoring instruments and threshold limit values for extremely low frequency-magnetic field (ELF-MF) methods. This study was undertaken through brief literature review. We performed a literature search in PubMed to identify ELF-MF studies conducted in workplaces. Initial search keywords such as 'extremely low frequency-magnetic field (ELF-MF)' and 'electromagnetic fields (EMF)' combined or singly. We limited our review to occupational rather than general nonworkplace environmental exposures. Methods: The contents we reviewed: key industry and occupations generating ELF-MF, several direct-reading instruments monitoring ELF-MF and threshold limit values (TLV) preventing health effects may be caused by the exposure to ELF-MF. Results: The industries related to the generation and supply of electricity, electrolytic installations, welding, and induction heating and more were regarded as high ELF-MF exposure industries. All jobs handling or employed performed in power cable lines, electrical wiring, and electrical equipment are found to be exposed to ELF-MF. Threshold or ceiling limit, 1,000 µT, is established to prevent acute effects of exposure to low-frequency EMFs on the nervous system: the direct stimulation of nerve and muscle tissues and the induction of retinal phosphenes. The International Agency for Research on Cancer (IARC) has classified ELF-MF as possibly carcinogenic to humans chiefly based on epidemiological studies on childhood leukemia. However, a causal relationship between magnetic fields and several types of cancer including childhood leukemia has not been established nor has any other long-term effects. Risk management using precautionary measures, has been initiated by the US and EU to prevent chronic health effects related to ELF-MF exposure in workplaces. Conclusion: This study recommends the implementation of various measures such as theestablishment of occupational exposure limit values for ELF-MF and precautionary principle to prevent potential chronic occupational health effects may be caused by ELF-MF in Korea.

• Journal of Power Electronics
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• 제11권3호
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• pp.294-303
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• 2011

In this paper an effective five-phase induction motor (IM) and its drive methods are proposed. Due to the additional degrees of freedom, the five-phase IM drive presents unique characteristics for enhancing the torque producing capability of the motor. Also the five-phase motor drives possess many other advantages when compared to traditional three-phase motor drives. Some of these advantages include, reducing the amplitude and increasing the frequency of the torque pulsation, reducing the amplitude of the current without increasing the voltage per phase and increasing the reliability. In order to maximize the torque per ampere, the proposed motor has concentrated winding, the produced back electromotive force (EMF) is almost trapezoidal, and the motor is supplied with the combined sinusoidal plus the third harmonic of the currents. For demonstrating the superior performance of the proposed five-phase IM, the motors are also analyzed on the synchronously rotating reference frame. To supply trapezoidal current waveform and to exclude the effect of the $3^{rd}$ harmonic current, a new control stratagem is proposed. The proposed control method is based on direct torque control (DTC) and rotor flux oriented control (RFOC) of the five-phase IM drives. It is able to reduce the acoustical noise, the torque, the flux, the current, and the speed pulsations during the steady state. The DTC transient merits are preserved, while a better quality steady-state performance is produced in the five phase motor drive for a wide speed range. Experimental results clearly demonstrated a more dynamic steady state performance with the proposed control system.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제52권6호
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• pp.254-261
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• 2003

This study investigates magnetic circuit design of the Single-phase Line-start Permanent Magnet Synchronous Motor (LSPM) to develop the characteristics in steady state. In this paper, the saliency ratio, that is the ratio of q-axial inductance to d-axial inductance, and the inductance difference between q-axial inductance and d-axial inductance are increased. Design factor is selected permanent magnet position and rotor diameter. The analysis method of the synchronous motor on d-/q- axis coordinates is used for the positive component and the equivalent circuit of the induction motor is applied for the negative component analysis. Back-emf and d-q- axial inductance is analyzed by using 2 dimensional Finite Element Method (FEM). Characteristic analysis results with variation of design factor are reflected magnetic circuit design of LSPM. The characteristics of design model are compared with the characteristic of initial model.