• Journal of Electrical Engineering and Technology
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• v.11 no.1
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• pp.241-246
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• 2016

This paper presents a method that can improve the performance of permanent magnet synchronous motor current control by minimizing the measured current phase delay caused by the Low Pass Filter(LPF) used to cut off the noises that flowed in when feedback currents are measured. Although existing methods that change the Cutoff Frequency of the LPF can minimize phase delays during high speed rotations, their noise cutoff effects are much lower and this may lead to the decline of control performance. Therefore, in this study, an algorithm that can compensate current phase delays through relatively simple calculations from the synchronous motor d-q axis coordinate transformation matrix and the inverse transformation matrix is proposed and the validity of the proposed method is verified by comparing the waveform of the calculated current with the waveform of actual currents through simulations and experiments.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.10
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• pp.3272-3281
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• 1996

The flow analysis method which had been developed for the numerical calculation of 3-dimensional, incompressible and turbulent flow within an axial compressor was extended to the flow field within centrifugal impeller. In this method based on the SIMPLE(Semi Implicit Method Pressure Linked Equations) algorithm, the coordinate transformation was adopted and the standard k-.epsilon. model using wall function was used for turbulent flow analysis. The calculated flow fields have agreed very well with measurement results. Especially, 3-dimensional and viscous flow characteristics including secondary flows, jet-wake flow and decreased pressure rise along impeller passage, which can't be predicted by inviscid Q3D calculation were predicted very reasonably.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.815-816
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• 2006

This paper proposes a novel design method for flux barrier which built in q-axis in rotor of IPM type BLDC motor. It aims to reduce the motor vibration with reduced cogging torque and lessened torque ripple by the sinusoidal waveform distribution of flux generated in the permanent magnet, which results from designed flux barriers. Design of flux barrier optimized using the Taguchi methods that considered multiple quality characteristics, such as cogging torque, average torque and efficiency are considered. The result of proposed method is compared and verified with 2D finite element method (FEM).

• Journal of Power Electronics
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• v.13 no.1
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• pp.77-85
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• 2013

This paper proposes a new dead time compensation method of independent six-phase permanent magnet synchronous motors (IS-PMSM). The current of the independent phase machines contains odd-numbered harmonics because of the dead time and the nonlinear characteristics of the switching devices. By using the d-q-n three-dimensional vector analysis, these harmonics can be extracted at the n-axis current. Thus, the current distortion can be compensated by controlling the n-axis current of the IS-PMSM to zero. The proposed method is simple and can be easily implemented without additional hardware setup. The validity of the proposed compensation method is verified with simulations and several experiments.

• Journal of Magnetics
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• v.22 no.1
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• pp.122-132
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• 2017

This study dealt with the design process of the 78 kW permanent magnet synchronous generator for engines. After the calculation of the basic dimensions through a theoretical method in the process of initial model design, FEA (finite-element analysis) and a d,q-axis equivalent circuit were used to identify the generator characteristics depending on the number of poles. With the use of the space harmonic analysis method, the back-EMF (electromotive force) and THD were checked, and then the number of slots was determined. In addition, the most optimized generator dimensions were determined through a sizing optimization technique. Based on this, the optimum model with enhanced efficiency, material costs, and temperature characteristics was derived, and the availability of the design method was confirmed through a comparative analysis of the initial and optimum models.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.11
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• pp.671-679
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• 2004

This paper presents the on-line current controller tuning method of grid-connected inverter using PSO(particle swarm optimization) technique for minimizing the harmonic current. Synchronous frame PI current regulator is commonly used in most distributed generation. However, due to the source voltage distortion, specially in weak AC power system, current may contain large harmonic components, which increase THD(total harmonic distortion) and deteriorates power quality. Therefore, some tuning method is necessary to improve response of current controller. This paper used the PSO technique to tune the current regulator and through simulation and experiments, usefulness of the tuning method has been verified. Especially in simulating the tuning process, ASM(average switching model) of inverter is used to shorten execution time.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.5 s.347
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• pp.35-44
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• 2006

Reflective semiconductor optical amplifiers(R-SOAs) were designed with high gain, wide optical bandwidth, high thermal reliability and wide modulation bandwidth in TO-can package for the transmitter of wavelength division multiplexed-passive optical network(WDM-PON) application. Double trench structure and current block layer were introduced in designing the active layer of R-SOA to enable high speed modulation. The injection power requirement and the viable temperature range of WDM-PON system are experimentally analysed in based on Amplified Spontaneous Emission(ASE)-injected R-SOAs. The effect of the different injection spectrum in the gain-saturated R-SOA was experimentally characterized based on the measurements of excessive intensity noise, Q factor, and BER. The proposed spectral pre-composition method reduces the bandwidth of injection source below the AWG bandwidth and thereby avoids spectrum distortion impeding the intensity noise reduction originated from the amplitude squeezing.

• Journal of fish pathology
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• v.24 no.2
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• pp.65-73
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• 2011

In analysis of DNA viruses from the contaminated shellfish using PCR, preparation method of template DNA is an important factor to get enough copy number of viruses. In this study, we evaluated the efficiency of PCR template of Megalocytivirus (sT50mg-D) DNA obtained from 50 mg digestive gland homogenate of oyster using commercial method, and compared with that obtained from 5 g of the same tissues (T5g-D) after PEG precipitation procedures of virus. Both templates DNA suspended in the same volume of distilled water showed positive results by primary PCR with 35 cycles, and the presence of Megalocytivirus was confirmed in oysters collected from cultured farms in Korea. Moreover, PCR with sT50mg-D allowed us to discriminate the contaminated oyster individually, that can not be done in PCR with T5g-D prepared from the mixture of three different individual oyster to get 5 g digestive gland homogenate. In quantitative analysis with real time PCR, Megalocytivirus concentrations in 50 ${\mu}l$ templates prepared using 0.5~50 mg of one positive sample were appeared in the range 6.14E+00~1.2E+02/${\mu}l$. We were not able to get positive result using template DNA contained less than 6.14E+00 copies. Consequently, 2-step PCR performed with DNA extracts from oyster homogenate of small amount (sT50mg-D) i) was enough to detect the contaminated Megalocytivirus in shellfish, ii) allowed us to do the analysis for individual shellfish rather than mixture of several shellfish and iii) showed the presence of Megalocytivirus in oyster from Korea.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.637-640
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• 1991

In this paper deals with linearized control of induction motor by vector control. Output equation induced from d-q axies voltage and current equation of induction moter. The condition of induced equation is that rotor's current of axies has 0 and state current of D axies which was driven by synchronous speed is constant. The fully digital controlled induction motor drive system based on the proposed linearized method and the control circuit of system consists of 16bits micro computer and all the function are implemented with software. When the voltage source inverter control with PI controller is empolyed, in spite of secondary resistance Rr Variation, the Vector control condition is satisfied.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.4
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• pp.203-208
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• 2006

This paper presents characteristics of SynRM(Synchronous Reluctance Motor) that is compared with a high speed induction motor. SynRM is much suitable for high speed electric machines because of structural robustness. There are many kinds of SynRM according to the shape of rotors. Particularly, axially laminated anisotropic (ALA) rotor is suitable for high speed instruments. Characteristics of SynRM with ALA rotor is obtained from a governing voltage and torque equation mainly composed of d-axis and q-axis inductance that will be identified with finite element method.