• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.11
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• pp.386-393
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• 2019

In this study, we investigated the cause of a voltage controller failure that occurred in the operation of a combat vehicle and attempted to establish a solution for the failure. The failure in the voltage controller was found to be related to thermal resistance, which could be identified by disassembly analysis and a high temperature operation test. Especially, in the disassembly analysis, there was damage caused by high temperature such as soot on the molding material and cracking of the resisters. In addition, in the high temperature operation test, the test results show that the internal temperature of the voltage controller was relatively higher than the external temperature. This means that the voltage controller failure could be attributed to the excessive heat and insufficient thermal resistance. In order to improve the thermal resistance of the voltage controller, several designs with changing circuits and structures were devised. Improvement of thermal resistance was verified by measuring reduction of internal temperatures in the high temperature comparison test.

• Journal of Electrical Engineering and Technology
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• v.10 no.1
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• pp.30-40
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• 2015

For a shunt power quality controller (SPQC) the DC side voltage value which is closely related to the compensation performance is a significant parameter. Buy so far, very little discussion has been conducted on this in a quantitative manner by previous publications. In this paper, a method to design the DC side voltage of SPQC is presented according to the compensation performance in the single-phase system and the three-phase system respectively. First, for the reactive current and the harmonic current compensation, a required minimal value of the DC side voltage with a zero total harmonic distortion (THD) of the source current and a unit power factor is obtained for a typical load, through the equivalent circuit analysis and the Fourier Transform analytical expressions. Second, when the DC side voltage of SPQC is lower than the above-obtained minimal value, the quantitative relationship between the DC side voltage and the THD after compensation is also elaborated using the curve diagram. Hardware experimental results verify the design method.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.8
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• pp.1207-1214
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• 2017

In the case of frequent braking, when driving downhill or long distance, conventional brakes using friction are problematic in braking safety due to brake rupture and fading phenomenon. Therefore auxiliary brakes is essential for heavy vehicles. And several research has been actively conducted to improve energy efficiency by regenerating mechanical energy into electric energy when the vehicles brake. In this paper, a voltage control method is utilized to recover the electric energy generated in the electromagnetic retarder instead of the eddy current. To regenerate the braking energy into the electrical energy, a resonant L-C circuit is configured in the retarder. The retarder can be modeled as self-excited induction generator due to its operating principle. The driving conditions according to the retarder's parameters are made into 3-D maps. Also, the voltage of the resonant circuit changing depending on the driving pulse applied to the FET was analyzed. For the control of this voltage, we proposed an algorithm using the PI controller. The controlled voltage is converted by a 3-phase AC/DC converter and then charged to a battery inside the heavy vehicles through a DC/DC converter. Electromagnetic retarder and its controller are validated using Matlab Simulink. We also demonstrate the voltage controller through the actual M-G set experiment.

• Proceedings of the KIPE Conference
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• 2012.11a
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• pp.29-30
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• 2012

This paper describes a fuzzy PI control method to control the output voltage of three-phase Z-source PWM rectifier. The proposed fuzzy PI controller is a single input fuzzy with its fuzzification, inferences and de-fuzzification processes. The proposed method adjusts the Kp and Ki in real time in order to find the most suitable Kp and Ki for PI controller and to simplify the controller design. The PI portion of DC voltage controller is controlled by fuzzy method. The simulation is performed with PSIM and MATLAB/SIMULINK and is verified the validity of the proposed approach.

• Proceedings of the IEEK Conference
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• 2002.06e
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• pp.71-74
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• 2002

We have development the dimming controller using the ac chopper technique. The ac chopper change the amplitude of the input source voltage with the unchanged its frequency. The conventional dimming controller is operated by controlling voltage phase and is consist of the triac. It has a bad characteristic about a current THD and a power factor. But the dimming controller using the at chopper technique has a low current THD and a good power factor. The developed dimming controller is consist of the MOSFET and the low pass filter. The system is operated by the variation circuit of the input source voltage and the microprocessor.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.4
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• pp.177-182
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• 2003

We have proposed the dimming controller using the AC chopper technique. The AC chopper changes the amplitude of the input source voltage with the same frequency. The conventional dimming controller is operated by controlling voltage phase with the triac. It has bad characteristics of the input current THD and the input power factor But the dimming controller using the ac chopper technique has a low current THD and a good power factor. The developed dimming controller is consist of the IGBT and the low pass filter. The system is operated by the variation circuit of the input source voltage and the microprocessor.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.4
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• pp.177-177
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• 2003

We have proposed the dimming controller using the AC chopper technique. The AC chopper changes the amplitude of the input source voltage with the same frequency. The conventional dimming controller is operated by controlling voltage phase with the triac. It has bad characteristics of the input current THD and the input power factor But the dimming controller using the ac chopper technique has a low current THD and a good power factor. The developed dimming controller is consist of the IGBT and the low pass filter. The system is operated by the variation circuit of the input source voltage and the microprocessor.

• Proceedings of the KIPE Conference
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• 2010.11a
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• pp.298-299
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• 2010

In this paper a robust voltage controller of single-phase inverter for UPS is presented. The voltage controller is designed using ${\mu}-based$ robust control scheme to simultaneously guarantee robust stability and robust tracking performance in presence of filter and load parameter variations. Firstly the robust performance of the resulting controller is theoretically confirmed via ${\mu}-analysis$. Then simulation results for single-phase inverter system with linear and nonlinear loads demonstrate feasibility of the proposed control method providing improved performance - good regulation and fast dynamic response.

• Journal of Power Electronics
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• v.10 no.5
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• pp.518-527
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• 2010

This paper presents a new technique for directly designing a linear digital controller for a single-phase pulse width modulation (PWM) converter systems, based on closed-loop identification. The design procedure consists of three steps. First, obtain a digital current controller for the inner loop system by using the error space approach, so that the power factor of the supply is close to one. The outer loop is composed of a voltage controller, a current control loop including a current controller, a PWM converter, and a capacitor. Then, all the components, except the voltage controller, are identified by a discrete-time equivalent linear model, using the closed-loop output error (CLOE) method. Based on this equivalent model, a proper digital voltage controller is then directly designed. It is shown through PSim simulations and experimental results that the proposed method is useful for the practical design of PWM converter controllers.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.778_779
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• 2009

The maximum output torque developed by the machine is dependent on the allowable current rating and maximum voltage that the inverter can supply to the machine. Therefore, to use the inverter capacity fully, it is desirable to use the control scheme considering the voltage and current limit condition, which can yield the maximum torque per ampere over the entire speed range. The paper is proposed maximum torque control of induction motor drive using adaptive learning neuro fuzzy controller and artificial neural network(ANN). The control method is applicable over the entire speed range and considered the limits of the inverter's current and voltage rated value. For each control mode, a condition that determines the optimal d, q axis current $_i_{ds}$, $i_{qs}$ for maximum torque operation is derived. The proposed control algorithm is applied to induction motor drive system controlled adaptive learning neuro fuzzy controller and ANN controller, the operating characteristics controlled by maximum torque control are examined in detail. Also, this paper is proposed the analysis results to verify the effectiveness of the adaptive learning neuro fuzzy controller and ANN controller.