• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.8
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• pp.98-104
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• 2013

AC machines are in wide use in industry and d-q transformation from 3 phase of a, b, c is commonly used to analyze these kinds of machines. The equivalent circuits of d and q axis are, however, generally cross coupled and difficult to analyze. In this study, a modeling technique of AC machine including induction and PM synchronous motors using matrix vector is proposed. With that model, it can not only explain the AC machines physically but also make it simple to analyze them. The separating process of d and q components is not needed in this model and this model can be applied to analyze asymmetric motors like IPMSM machine. With this technique, the model becomes simple, easy to understand physically, and yields results that are the same as those from other models. These simulation results of the proposed model for induction motor are compared with those of other models to verify the method proposed.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.11
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• pp.30-35
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• 2021

In this study, a machine simulation system was built using the actual scale of an AC-type 5-axis machine tool for mold surface machining that can be used in applications, such as, modeling and machine building, stroke, and collision detection. The validity of the 5-axis machine simulation system was verified by performing tool path generation, post-processing, machine simulation, prototype motion simulation, and an actual cutting experiment. This entire process was intended to activate the 5-axis machining in mold surface machining.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.663-667
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• 1998

This paper describes for reducing harmonic distortion on CO2 welding machine with nonlinear load characteristic using single-switch three-phase AC/DC converter. The low-order harmonic component amplitude of the phase current of single-switch three-phase discontinuous mode is calculated. Experimental results show that CO2 welding machine with single-switch three-phase AC/DC converter is effectively controlled with power factor correction for phase current during welding time.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.10a
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• pp.159-163
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• 2003

In recent days, as the efficiency of electronic home applications become higher, that of the driving AC motor become higher. On this reason, the demand fir high capacity coil firming machine is increasing. Since the coil forming is not simply related with the only capacity of hydraulic cylinder, the development of a newer coil firming machine which has new filming mechanism new driving method, new filming tool, and new specification is required. In this paper, the virtual prototype which have new mechanism is developed. This prototype is tested and experimented on PC with the same condition as actual. The results from the virtual experiment is applied to the actual design process.

• Journal of Power Electronics
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• v.15 no.2
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• pp.411-418
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• 2015

In this paper, a new method for the online estimation of equivalent series resistances (ESR) of the DC-link capacitors in induction machine (IM) drive systems with a front-end diode rectifier is proposed, where the ESR estimation is conducted during the regenerative operating mode of the induction machine. In the first place, a regulated AC current component is injected into the q-axis current component of the induction machine, which induces the current and voltage ripple components in the DC-link. By processing these AC signals through digital filters, the ESR can be estimated by a recursive least squares (RLS) algorithm. To acquire the AC voltage across the ESR, the DC-link voltage needs to be measured at a double sampling frequency. In addition, the ESR current is simply reconstructed from the stator currents and switching states of the inverter. Experimental results have shown that the estimation error of the ESR is about 1.2%, which is quite acceptable for condition monitoring of the capacitor.

• Proceedings of the KIEE Conference
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• summer
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• pp.1196-1198
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• 2004

This paper represents the improvement of floating point operation for AC servo motor controller based on fixed point operation DSP. TMS320F2812 has fixed point operation processing structure. The controller parameters are modified to the digitized data by scaling the original parameters. TMS320F 2812 is a 32-bit processor, and it could have enough accuracy to got the digitized data this procedure is implemented and the experiments controling a AC servo system.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.519-521
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• 1994

In this paper, the welding machine with high-frequency inverter is described, which can save energy more than conventional ones with low efficiency. Although for part of welding machine of special type such as MIG, TIG, products were developed by inverter, but it is poor that applied to ordinary ac arc welding machine. Difference between conventional AC arc welding machine and the proposed welding machine is investigated econimically and constructionally. Untill now, kinds of welding machine and its characteristics were also described. The comparison of the proposed welding machine and the conventional is presented in the way of output control.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.299-303
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• 2003

This paper deals with the frequency sensing methods at HVDC system. The objects of frequency information in HVDC system areto fire a valve and to control a frequency of AC network. Conventionally, there are two methods to measure a frequency of AC network. The first method is to draw out from the synchronous machine and the second method is from AC network. Two methods have advantages and disadvantage each other. For the extreme case of a receiving system of zero inertia (no generation), synchronous machine is essential. In this situation, the frequency information received from the synchronous machine shaft. However, the speed of synchronous machine is oscillated when a disturbance in AC network occurs, and HVDC may be oscillated due to an oscillation speed. To solve this drawback, in this paper, new frequency sensing method is proposed. A proposed method that is use a modified curve-fitting algorithm, has a robust characteristics against a harmonics and unbalanced faults. Consequently, A proposed method is verified by PSCAD/EMTDC Program and experimental test.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1939-1941
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• 2000

Nondestructive and destructuve insulation tests were performed the high voltage rotating machine in the local thermal power plants. Nondestructive tests include measurements of insulation resistance. polarization index, AC current. tan$\delta$, partial discharge. Destructive tests include measurements of AC hipot and DC hipot. This paper propose to establish the insulation diagnosis cycle for high voltage rotating machine.

• Journal of Power Electronics
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• v.12 no.2
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• pp.276-284
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• 2012

AC/AC power conversion is widely used to feed AC loads with a variable voltage and/or a variable frequency from a constant voltage constant frequency power grid or to connect critical loads to an unreliable power supply while delivering a very balanced and accurate sinusoidal voltage system of constant amplitude and frequency. The load specifications will clearly impose the requirements for the inverter stage of the power converter, while wider ranges of choices are available for the rectifier. This paper investigates the utilization of a buck-type current source rectifier as the active front-end stage of an AC/AC converter for applications that require an adjustable DC-link voltage as well as elimination of the low-frequency common mode voltage. The proposed solution is to utilize a combination of two or more zero current vectors in the Space Vector Modulation (SVM) technique for Current Sources Rectifiers (CSR).