• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.2
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• pp.111-117
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• 2005

Several of the conventional hydraulic systems in an automobile are now being replaced by more reliable and energy efficient electromechanical systems. Developments in the brushless permanent magnet machine and in the power and control electronics are the key factors responsible for this transformation. These applications brought out some performance challenges associated with the brushless machines. This paper will focus on these challenges to be able to use these machines in such applications. In terms of replacing hydraulic systems with electromechanical systems, steering system is leading the way in automobiles. Currently, steering systems using Electro-hydraulically assisted systems and Electrically assisted (Electromechanical) systems are in the market. Though the Electrically assisted power steering has several advantages over other systems, certain performance and cost challenges delayed the penetration of such systems in to the market.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.741-745
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• 2001

Reliability and safety of steer-by-wire concepts can be achieved by redundant designs. This paper discusses the design of a fault tolerant concept for a force feedback actuator with a standard three-phase PMSM. In contrast to usual drives, the phases of the machine are separated electrically. This design allows driving the machine with two instead of three phases in case of a fault. A superimposed torque controller adjusts the influence of fault currents and torque harmonics in two-phase operation and guarantees smooth torque at the steering wheel

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.5
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• pp.632-638
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• 2013

In this study, we described voltage fluctuation characteristics of distribution line during starting and normal operation condition of the small hydro generators. Based on these theories, we scrutinized the starting and operating characteristics of induction generators installed in two small hydro power plants that is connected to the distribution line and researched necessary factors when selecting the generator type. The type of turbines and capacity of generators are different. One is below 1,000kW and the other is above 1,000kW. Two generators are tested during starting, and it acts as motor not generator at the instant that the machine is connected to the grid. After connecting to the grid, the machine rotates above synchronous speed before converting to the generator mode. Therefore the characteristic of the generator during starting is same as it of motor.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.6
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• pp.23-30
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• 2013

This paper shows the method of winding connection and the balance of three phase of dual inverter systems used for offshore wind power generator. In order to satisfy low cost manufacturing of large scaled wind generator, the number of slot per pole per phase should be reduced. For this reason, in this research, the number is selected as '1' which is the minimum number that stator can have. Based on the prototype machine, three types of machine for the analysis are selected, and various performances especially in terms of electrically balanced condition are also investigated. Moreover, in this paper, new inductance modeling of dual 3-phase considering cross-coupling between two inverter systems is proposed. The several inductances such as mutual-, synchronous inductances are studied. By using FEA, based on calculated the flux linkage of d and q-axis, the validity of the proposed inductance modeling is confirmed.

• Journal of Power Electronics
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• v.9 no.3
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• pp.438-446
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• 2009

The performance of direct torque controlled (DTC) interior permanent magnet (IPM) machines is poor at low speeds due to a few reasons, namely limited accuracy of stator voltage acquisition and the presence of offset and drift components in the acquired signals. Due to factors such as forward voltage drop across switching devices in the three phase inverter and dead-time of the devices, the voltage across the machine terminals differ from the reference voltage vector used to estimate stator flux and electromagnetic torque. This can lead to instability of the IPM drive during low speed operation. Compensation schemes for forward voltage drops and dead-time are proposed and implemented in real-time control, resulting in improved performance of the space vector modulated DTC IPM drive, especially at low speeds. No additional hardware is required for these compensators.

• Journal of Ocean Engineering and Technology
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• v.16 no.5
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• pp.61-65
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• 2002

The fault detection and diagnosis of rotating machinery widely used in plants including the ship are important for maintaining the performance of Plants. Recently, the wavelet transform has been recognized an efficient method to detect a little variation of physical quantities by the synchronous localization of time and frequency domains using the translation and dilation of signals. In this Paper, In order to develop efficient and reliable fault detection and diagnosis system rotating machines, the performance of wavelet transformation to detect a little variation of machine status and neural network to diagnose the cause of machine faults are investigated and experimented.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.862-863
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• 2015

This paper presents an improved estimation procedure for the contribution to no-load flux linkage created by the permanent magnet (PM) in interior permanent magnet synchronous machines. In the proposed method, the saturation effect in stator and rotor cores are taken into account by utilizing the frozen permeability method (FPM). This improved procedure can evaluate the contribution for each local element in the PM to the no-load flux linkage. According to the analysis results, an effective PM topology optimal design can be carried out to achieve high utilization ratio of PM in the machine. In order to determine the threshold of the low contribution of PM for removing, one multi-objective optimization model is proposed. Based on the optimal threshold, the final optimal topology design of PM can be achieved.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.119-124
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• 1999

This paper presents new approach to technology pattern recognition of camera back cover and test of soldering. In real-time implementing of pattern recognition camera back cover and test of soldering, the MVB-03 vision board has been used. Image can be captured from standard CCD monochrome camera in resolutions up to 640$\times$480 pixels. Various options re available for color cameras, a synchronous camera reset, and linescan cameras. Image processing os performed using Texas Instruments TMS320C31 digital signal processors. Image display is via a standard composite video monitor and supports non-destructive color overlay. System processing is possible using c30 machine code. Application software can be written in Borland C++ or Visual C++

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.11a
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• pp.179-183
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• 1999

Rubbing occurs when a rotating element comes in contact with a stationary element. In the steam turbines, the rotating element is the rotor while the stationary elements are usually the oil deflectors and packing seals. Rubbing phenomenon may be often obseued on a new or rebuilt machine rather than on a machine that has been operating for several months or years. Rubbing in the turbine has been classified into two modes by the operating conditions: 1) start up or shut down, 2) steady state. At start up or shut down operation, rubbing produces synchronous whirl vibration, which are caused by thermal bow of the shaft due to localized heating on the shaft surface. While subsynchronous whirl vibration is caused by partial rubbing during the steady state operation. In this paper, the two case studies of troubleshooting for excessive vibration caused by rubbing in the actual steam turbines are investigated.

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.1968-1971
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• 2002

In this paper, we have presented a test- ing method for a kind of asynchronous circuits. Tar- get circuit model is the 3D machine that is one of the most successful implementation of extended burst-mode (XBM) machines. We present a high-level test generation method for the 3D machine using the specification of the circuit. We also present a gate-level test pattern generation method using a synchronous test pattern generator. Experimental results show that the combination of the above two methods achieves high fault coverage over 3D machines and saves test generation time.