• The Transactions of the Korean Institute of Electrical Engineers P
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• v.60 no.3
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• pp.126-132
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• 2011

A conventional LDO(Low Dropout Regulator) uses one OPAMP and one signal path. This means that OPAMP's DC Gain and Bandwidth can't optimize simultaneously within usable power. This also appears that regulation property and settling time of LDO can't improve at the same time. Based on this idea, a proposed LDO uses two OPAMP and has two signal path. To improve regulation property, OPAMP where is used in the path which qualities DC gain on a large scale, bandwidth designed narrowly. To improve settling time, OPAMP where is used in the path which qualities DC gain small, bandwidth designed widely. A designed LDO used 0.5um 1P2M process and provided 200mA of output current. A line regulation and load regulation is 12.6mV/V, 0.25mV/mA, respectively. And measured settling time is 1.5us in 5V supply voltage.

• Journal of Power Electronics
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• v.15 no.6
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• pp.1508-1516
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• 2015

A single phase H-bridge inverter is employed in conventional Inductive Power Transfer (IPT) systems as the primary side power supply. These systems may not be suitable for some high power applications, due to the constraints of the power electronic devices and the cost. A high-frequency cascaded multi-level inverter employed in IPT systems, which is suitable for high power applications, is presented in this paper. The Phase Shift Pulse Width Modulation (PS-PWM) method is proposed to realize power regulation and selective harmonic elimination. Explicit solutions against phase shift angle and pulse width are given according to the constraints of the selective harmonic elimination equation and the required voltage to avoid solving non-linear transcendental equations. The validity of the proposed control approach is verified by the experimental results obtained with a 2kW prototype system. This approach is expected to be useful for high power IPT applications, and the output power of each H-bridge unit is identical by the proposed approach.

• Journal of Power Electronics
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• v.16 no.4
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• pp.1268-1276
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• 2016

A triode for alternating current (TRIAC) dimming light emitting diode (LED) driver, which adopts a variable switched capacitor for LED dimming and LED power regulation, is proposed in this paper. The proposed LED driver is power efficient, reliable, and long lasting because of the TRIAC switch that serves as its main switch. Similar to previous TRIAC dimmers for lamps, turn-on timing of a TRIAC switch can be controlled by a volume resistor, which modulates the equivalent capacitance of the proposed variable switched capacitor. Thus, LED power regulation against source voltage variation and LED dimming control can be achieved by the proposed LED driver while meeting the global standards for power factor (PF) and total harmonic distortion (THD). The long life and high power efficiency of the proposed LED driver make it appropriate for industrial lighting applications, such as those for streets, factories, parking garages, and emergency stairs. The detailed analysis of the proposed LED driver and its design procedure are presented in this paper. A prototype of 80 W was fabricated and verified by experiments, which showed that the efficiency, PF, and THD at V_s = 220 V are 93.8%, 0.95, and 22.5%, respectively; 65 W of LED dimming control was achieved with the volume resistor, and the LED power variation was well mitigated below 3.75% for 190 V < V_s < 250 V.

• Journal of Power Electronics
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• v.5 no.2
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• pp.109-119
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• 2005

This paper deals with the performance analysis of static compensator (STATCOM) based voltage regulator for self­excited induction generators (SEIGs) supplying balanced/unbalanced and linear/ non-linear loads. In practice, most of the loads are linear. But the presence of non-linear loads in some applications injects harmonics into the generating system. Because an SEIG is a weak isolated system, these harmonics have a great effect on its performance. Additionally, SEIG's offer poor voltage regulation and require an adjustable reactive power source to maintain a constant terminal voltage under a varying load. A three-phase insulated gate bipolar transistor (IGBT) based current controlled voltage source inverter (CC- VSI) known as STATCOM is used for harmonic elimination. It also provides the required reactive power an SEIG needs to maintain a constant terminal voltage under varying loads. A dynamic model of an SEIG-STATCOM system with the ability to simulate varying loads has been developed using a stationary d-q axes reference frame. This enables us to predict the behavior of the system under transient conditions. The simulated results show that by using a STATCOM based voltage regulator the SEIG terminal voltage can be maintained constant and free from harmonics under linear/non linear and balanced/unbalanced loads.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.5
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• pp.2249-2253
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• 2011

This paper analyzed the problems of the Korean output regulation in the relevant band through an analytic comparison of the current trend of each country and their standard values concerning the technical standard of low power u-IT equipments. In connection with the standard value of technical values of each country, which has been proposed in the registration of the appropriate electric wave, the paper aims to propose the standard value that could actually be introduced for suitable low power u-IT installations in Korea. Provided that the Korean standard may be upgraded based on the tolerances of technical standards proposed in this paper, this is expected to be committed to the distribution and advancement of low power u-IT equipments; and further, it is anticipated to be prepared with competitiveness not only in the Korean communications market, but also in the international communications market.

• Journal of Electrical Engineering and Technology
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• v.11 no.2
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• pp.300-308
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• 2016

Application of demand-side resources to automatic generation control (AGC) has a great significance for improving the dynamic control performance of power system frequency regulation. This paper investigates the possibility of providing regulation services by demand-side energy storage in electric vehicle battery swapping stations (BSS). An interaction framework, namely station-to-grid (S2G), is presented to integrate BSS energy storage into power grid for giving benefits to frequency regulation. The BSS can be regarded as a lumped battery energy storage station through S2G framework. A supplementary AGC method using demand-side BSS energy storage is developed considering the vehicle user demand of battery swapping. The effects to the AGC performance are evaluated through simulations by using a two-area interconnected power grid model with step and random load disturbance. The results show that the demand-side BSS can significantly suppress the frequency deviation and tie-line power fluctuations.

• Journal of Electrical Engineering and Technology
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• v.8 no.4
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• pp.667-674
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• 2013

Wind power producers face many regulation costs in deregulated environment, which remarkably lowers the value of wind power in comparison with conventional sources. One of these costs is associated with the real-time variation of power output and being paid in frequency control market according to the variation band. This paper presents a new approach to coordination of battery energy storage in wind generation system for reducing the payment in frequency control market. The approach depends on the statistic data of wind generation and the prediction of frequency control market price to determine the optimal variation band which is then kept by the real-time charging and discharging of batteries, ultimately the minimum cost of frequency regulation can be obtained. The optimization problem is formulated as trade-off between the decrease in the regulation payment and the increase in the cost of using battery, and vice versus. The approach is applied to a study case and the results of simulation show its effectiveness.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1998.06a
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• pp.432-437
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• 1998

Power systems have uncertain dynamics due to a variety of effects such as lightning, severe storms and equipment failures. The variation of the effective reactance of a transmission line due to a fault is an example of uncertainty in power system dynamics. Hence, a robust controller to cope with these uncertainties is needed. Recently fuzzy controllers have become quite popular for robust control due to its capability of dealing with unstructured uncertainty. Thus in this paper we design an adaptive fuzzy controller using an input-output linearization approach for the transient stabilization and voltage regulation of a power system under a sudden fault. Simulation results show that satisfactory performance is achieved by the proposed controller.

• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.208-211
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• 2003

This paper presents an improved droop method of the high voltage DC power supply which minimizes the voltage droop of a parallel-connected power supply. Conventionally, the droop method has been used to achieve a simple structure and no-interconnections among the power sources. However, it has a trade-off between output voltage regulation and load sharing accuracy. In this paper, the droop is minimized with a current and droop gain control using steady-stage estimation. The proposed method can achieve both high performance voltage regulation and load sharing. Two 10kV, 100mA parallel power modules were made and tested to verify the proposed current-sharing method.

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.4
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• pp.281-290
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• 2012

This paper describes a Cross-regulation characteristics of a multi-output LLC resonant converter widely used in consumer electronics. The output characteristics of the multi-output LLC converter is derived from the assumption that the current and voltage in the resonant network is sinusoidal and the duty loss exists. The simulation and experimental results are provided to verify the theoretic results.