• Journal of Electrical Engineering and Technology
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• 제9권6호
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• pp.1935-1943
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• 2014

In recent years, the induction machines are increasingly being used as self-excited induction generators (SEIG). This generator is especially widely employed for small-scale power plants driven by renewable energy sources. The application of power electronic components in the induction generator control (IGC) and the loading of SEIG using nonlinear loads will generate harmonic currents. This paper analyzes the propogation of harmonic currents on the SEIG with nonlinear loads. Transfer function method in the frequency domain is used to calculate the gain and phase angle of each harmonic current component which are generated by a nonlinear loads. Through the superposition approach, this method has also been used to analyze the propagation of harmonic currents from nonlinear load to the stator windings. The simulation for the propagation of harmonic currents for a 4 pole, 1.5 kW, 50Hz, 3.5A, Y-connected, rotor-cage SEIG with energy-saving lamps, have provided results almost the same with the experiment. It can prove that the validity of the proposed models and methods. The study results showed that the propagation of harmonic currents on the stator windings rejects high order harmonics and attenuates low order harmonics, consequently THDI diminish significantly on the stator windings.

• Journal of Power Electronics
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• 제8권2호
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• pp.181-191
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• 2008

The task performed by induction motors grows increasingly complex in modern industry and hence improvements are sought in the field of fault diagnosis. It is essential to diagnose faults at their very inception, as unscheduled machine down time can upset critical dead lines and cause heavy financial losses. Artificial intelligence (AI) techniques have proved their ability in detection of incipient faults in electrical machines. This paper presents an application of AI techniques for the detection of inter-turn insulation and bearing wear faults in single-phase induction motors. The single-phase induction motor is considered a proto type model to create inter-turn insulation and bearing wear faults. The experimental data for motor intake current, rotor speed, stator winding temperature, bearing temperature and noise of the motor under running condition was generated in the laboratory. The different types of fault detectors were developed based upon three different AI techniques. The input parameters for these detectors were varied from two to five sequentially. The comparisons were made and the best fault detector was determined.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2005년도 춘계학술대회논문집
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• pp.473-478
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• 2005

In home appliances, electric energy is optimally controlled by using power electronics technology, creating a comfortable environment in terms of energy saving, low sound generation, and reduced time consumption. Usually simplicity and robustness make the three phase induction motor attractive for use in domestic appliance, including washing machines. Two main fpes of domestic washing machine have evolved. We focus on the front loading machine favored in Europe, which has a horizontal drum axis. With the advent of electronic control, universal motor, with a phase controller operating directly from the ac source, has become popular in washing machine. The efficiency improvement in home appliances is very important for customers. Induction motor efficiency can be improved by means of loss reduction, which can be realized by motor selection and design, improvement of the waveforms supplied by power inverter, utilizing a suitable control method. So this paper describes the architecture and feature of washing machine fed induction motor drive under minimizing losses vector control.

• Journal of Power Electronics
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• 제16권2호
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• pp.572-583
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• 2016

In view of the speed control characteristics of induction traction motors and the problems of direct torque control (DTC) algorithms in current applications, this paper presents a DTC algorithm characterized by a symmetrical polygon flux control and a closed loop power control in the constant-torque base speed region and constant-power field-weakening region of induction traction motors. This algorithm only needs to add a stator flux control algorithm to the traditional DTC structures. This has the benefit of simplicity, while maintaining the features of traditional algorithms such as a rapid dynamic response, uncomplicated control circuit, reduced dependence on motor parameters, etc. In addition, it obtains a smoother flux trajectory that is conducive to improvement of the harmonic elimination capability, the switching frequency utilization as well as the torque and power performance in the field-weakening region. The effectiveness and feasibility of this DTC algorithm are demonstrated by both theoretical analysis and experimental results.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제11B권2호
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• pp.51-58
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• 2001

This paper proposes a new strategy to estimate the rotor flux of an induction machine for the direct field oriented control. Electrical model of the induction machine presents the basic idea based on observer structure, which is composed of voltage model and current model. But the former has the defects in low speed range, the latter has the defects of sensitivity to machine parameters. In spite of these shortcomings, the closed loop flux observer based on two models has been prevalent estimation method for the direct field oriented control. In this paper, generalized analysis method named "observer characteristic function method"is proposed to analyze the kinds of the linear flux observers in unified form. With the observer characteristic function, the estimated rotor flux error involved in the classical methods can be easily clarified. Moreover, the novel rotor flux observer based on this analysis is also presented and the effectiveness of the observer has been verified by the simulation and experimental results.

• 조명전기설비학회논문지
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• 제29권11호
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• pp.35-40
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• 2015

In accordance with global energy conservation policies such as MEPS (Minimum Energy Performance Standard), electric motor industry is moving to super-high-efficiency machines and research to develop IE4 (International Energy Efficiency Class 4) motors has been launched. In this situation, SynRM (Synchronous Reluctance Motor) has been attracting attention in place of induction motor which hardly provides super premium efficiency. As a result, much research on SynRM is being performed at home and abroad. Also, some products have already been appearing in the market. Compared to induction motor, SynRM has better efficiency per unit area and wider operating range. Although the utilization of control system in synchronous motor results in higher prices, we still need to concentrate on developments of SynRM so as to comply with the new policies. This study demonstrated the electromagnetic design methods of super premium SynRM while maintaining the frame of existing IE3 induction motor. We documented the design procedures for generating high saliency which is the most essential and mechanical stress anlaysis is also treated. In conclusion, we proved the validity of our design by manufacturing and testing our 3 models.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 추계학술대회 논문집
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• pp.338-345
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• 2013

Induction motors play an increasing importance in industrial manufacturing. Therefore, the state monitoring systems also have been considering as the key in dealing with their negative effect by absorbing faulty symptoms in motors. There are numerous proposed systems in literature, in which, several kinds of signals are utilized as the input. To solve the multiple faults problem of induction motors, like the proposed system, the vibration signals is good candidate. In this study, a new signal processing scheme was utilized, which transforms the time domain vibration signal into the spatial domain as an image. Then the spatial features of converted image then have been extracted by applying the dominant neighbourhood structure (DNS) algorithm. In addition, these feature vectors were evaluated to obtain the fruitful dimensions, which support to discriminate between states of motors. Because of reliability, the conventional one-against-all (OAA) multi-class support vector machines (MCSVM) have been utilized in the proposed system as classifier module. Even though examined in severity levels of signal-to-noise ratio (SNR), up to 15dB, the proposed system still reliable in term of two criteria: true positive (TF) and false positive (FP). Furthermore, it also offers better performance than five state-of-the-art systems.

• 동력기계공학회지
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• 제21권3호
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• pp.37-44
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• 2017

In this study, failure analysis of the angular pin for molding machines to aluminum component molding was carried out. SM45C steel was used for the angular pin, it was surface hardened by the induction surface hardening heat treatment. The cross section of damaged angular pin was observed, and micro Vickers hardness value from the fractured part was measured. Brittle fracture was occurred from the fracture surface of angular pin, therefore, impact toughness value was evaluated by V-notch Charpy impact test. It was confirmed that the impact absorption energy was high when was tempered at a high temperature for a long time, and the toughness was slightly increased. Also, 2-parameter Weibull statistical analysis was investigated in order to evaluate the reliability of the measured micro Vickers hardness values and absorbed energy. The micro Vickers hardness and absorbed energy well followed a two-parameter Weibull probability distribution, respectively. The reverse design against angular pin was proposed as possible by using test results.

• Journal of Power Electronics
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• 제19권4호
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• pp.968-979
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• 2019

Recently, there has been increased interest in the study of multiphase machines due to their higher fault-tolerant capability when compared to their conventional three-phase counterparts. For six-phase machines, stator windings configured with a single isolated neutral (1N) provide significantly more post-fault torque/power than two isolated neutrals (2N). Hence, this configuration is preferred in applications where post-fault performance is critical. It is well known that min-max injection has been commonly used for three-phase and multiphase machines in healthy condition to maximize the modulation limit. However, there is a lack of discussion on min-max injection for post-fault condition. Furthermore, the effects in terms of the common-mode voltage (CMV) in modulating signals has not been discussed. This paper investigates the effect of min-max injection in post fault-tolerant control on the voltage and speed limit of a symmetrical six-phase induction machine with single isolated neutral. It is shown that the min-max injection can minimize the amplitude of reference voltage, which maximizes the modulation index and post-fault speed of the machine. This in turn results in a higher post-fault power.

• Journal of international Conference on Electrical Machines and Systems
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• 제3권2호
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• pp.207-214
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• 2014

If two or more Permanent Magnet Synchronous Motors (PMSM) can be controlled by one inverter, a train can be driven by less energy than the present Induction Motor (IM) drive system. First, this paper proposes a method for simulating the movement of wheels and a vehicle to develop a control method. Next, a method is presented for controlling two or more PMSMs by one inverter.