• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.5
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• pp.448-457
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• 2013

This paper proposes a control method under stand-alone operating mode for distributed-module type photovoltaic power conditioners. In conventional schemes, there are some problems of a controller saturation in the DC-link (or load) voltage controller when overly-heavy load, light load, and the generated PV power reduction occurs, as well as when a transition occurs from an overly-loaded to normal conditions. To overcome these problems, the proposed controller method switches the main control target from DC-link voltage to the maximum power point, which is closer to the stable operating point when it returns to normal operating conditions. For the analysis, a state-plane trajectory was given and the circuit analysis by PSIM simulation was done. For the verification, a prototype hardware with 110[W] and 50[W] dual photovoltaic modules has been implemented. From the results, it can be seen that PV power tracking is successfully done with the proposed method even under a stand-alone operation mode.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.2051-2054
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• 2004

This paper proposes a more accurate task level energy measurement technique for high speed microprocessors. The technique is based on the relationship of the amount of current consumed by the microprocessor and the pulse width of the power supply controller chip, employed in the synchronous buck DC-DC converter in the microprocessor's power supply. The accuracy of the measurement is accomplished by measuring variation in pulse width in each power supply cycle. The major advantage of this technique is that its accuracy does not depend on the operating frequency of the microprocessor. To prove the proposed technique, we implemented the measurement unit of the microprocessor energy meter using an FPGA chip operating at 50 MHz. Both static and dynamic load measurement are tested in order to obtain some behaviours. Moreover, various commercially available mainboards which employ synchronous buck regulators at 200 KHz switching frequency, were measured. The results agree with previous works with better accuracy at higher operating frequency.

• Journal of Power Electronics
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• v.13 no.4
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• pp.729-736
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• 2013

Knowledge of a power semiconductor's operating temperature is important in circuit design and converter control. Designing appropriate circuitry that does not affect regular circuit operation during virtual junction temperature measurement at actual operating conditions is a demanding task for engineers. The proposed method enables virtual junction temperature estimation with a dedicated modified gate driver circuit based on real-time measurement of a semiconductor's quasi-threshold voltage. A simulation was conducted before the circuit was designed to verify the concept and to determine the basic properties and potential drawbacks of the proposed method.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.4
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• pp.93-99
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• 2008

The clutch is a subcomponent of the transmission that is designed to engage and disengage power flow between the engine and the transmission. Recently, the engine power of automobile has been continuously increased because of customer's demand for the bigger one. As the engine power is increased, the vibration transmitted to the hydraulic clutch operating system has been increased. Therefore the demand for the reduction of clutch pedal vibration during the operation of the clutch system has been increased. This paper describes the pressure pulsation reduction characteristics of the damper cylinder which is applied to the hydraulic clutch operating system. And the purpose of this study is to confirm the availability of a simulation model and investigating the test results of hydraulic clutch operating system. The test results are compared with the simulation results. Therefore it may be concluded that the simulation model and test results will be very useful f3r the design of hydraulic clutch damper cylinder.

• 전기의세계
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• v.24 no.5
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• pp.97-102
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• 1975

This paper describes the result of a Study for the Optimum Operating method with Spinning reserve in case of outage of large generator unit to improve the system stability and prevent the system frequency drop. This is usually done by governor free operation, so we focused our attention to the operating Char acteristics of spinning reserve. Nexy, a study was made to mesure the upper limit of Spinning reserve and when this upper limit cannot match the required power, a relationship between the amount of spinning reserve and that of the load shedding requirement was searched with regard to several system operating conditions to use it in our future system operation. By this study, the optimum system operating method was recommended for reliable operation of power system.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2003.11a
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• pp.169-173
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• 2003

This paper analyzes the effects of various operating voltages on the electrical and light output characteristics of 20mW(5mm-Ф), 1W and 5W high-power RGB LEDs. Operating voltages of three types are compared on a simple LED circuit: DC, full-wave rectified DC. and square-wave DC. As a result, it is found that the 1W and 5W high-power LEDs should be provided with appropriate heat sinks that hold down the increase of junction temperature. As for the operating efficiency the case of full-wave rectification gives the highest value.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.4
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• pp.290-294
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• 2014

PID(Proportional, Integral, Derivative) controller is the most popular process controllers in nuclear power plants. The optimized parameter setting of the process controller contributes to the stable operation and the efficiency of the operating nuclear power plants. PID parameter setting is tuned when new process control systems are installed or current process control systems are changed. When the nuclear plant is shut down, a lot of PID tuning methods such as the Trial and Error method, Ultimate Oscillation method operation, Ziegler-Nichols method, frequency method are used to tune the PID values. But inadequate PID parameter setting can be the cause of the unstable process of the operating nuclear power plant. Therefore the results of PID parameter setting should be simulated, optimized and finally verified. This paper introduces the simulation method of PID tuning to optimize the PID parameter setting and confirms them of the actual PID controller in the operating nuclear power plants. The simulation method provides the accurate process modeling and optimized PID parameter setting of the multi-loop control process in particular.

• Journal of Power Electronics
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• v.9 no.5
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• pp.772-780
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• 2009

A novel soft-switching two-switch flyback converter is proposed in this paper. This converter is composed of two active power switches, a flyback transformer, a blocking diode, and two passive regenerative clamping circuits. The proposed converter has the advantages of a low cost circuit configuration, a simple control scheme, a high efficiency, and a wide operating range. The circuit topology, analysis, design considerations, and experimental results of the new flyback converter are presented.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.987-992
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• 1998

Solar cell has an optimum operating point to extract maximum power. To control operating point of the solar cell, a fuzzy controller has already been proposed by our research group. However, several parameters are determined by trial and error. To overcome this problem, this paper adopts Fuzzy Neural Network (FNN) for maximum power point tracking control for photovoltaic array. The FNN can be trained to perfect fuzzy rules and to find an optimum membership functions on-line.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.359-359
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• 2000

Generally, level control in the steam generator of a nuclear power plant is difficulty process control, because the low power operating can lead nonminimum phase characteristics(swell and shrink phenomenon) and flow measurement are unreliable and nonlinear characteristics. This paper presents a framework for solving this problem based on the constrained linear model predictive control and introduces the design of method for the level of the controller in the entire operating power of the steam generator, and compares with conventional PI controller.