• Journal of Power Electronics
• /
• v.16 no.2
• /
• pp.414-424
• /
• 2016

This paper proposes a novel high-efficiency high-step-up interleaved converter with a voltage multiplier, which is suitable for electric vehicle power management applications. The proposed interleaved converter is capable of achieving high step-up conversion by employing a voltage-multiplier circuit. The proposed converter lowers the input-current ripple, which can extend the input source's lifetime, and reduces the voltage stress on the main switches. Hence, large voltage spikes across the main switches are alleviated and the efficiency is improved. Finally, a prototype circuit with an input voltage of 24 V, an output voltage of 380 V, and an output rated power of 1 kW is implemented and tested to demonstrate the functionality of the proposed converter. Moreover, satisfying experimental results are obtained and discussed in this paper. The measured full-load efficiency is 95.2%, and the highest measured efficiency of the proposed converter is 96.3%.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.56 no.11
• /
• pp.1910-1920
• /
• 2007

This paper deals with the optimal evaluation algorithms for voltage regulation in the case where new dispersed generations(DG) are operated in distribution systems. It is very difficult and complicated to handle the interconnection issues for proper voltage managements, because professional skills and enormous amounts of data for the evaluations are required. The typical evaluation algorithms mainly depending on human ability and quality of data acquired, inevitably cause the different results for the same issue, so unfair and subjective evaluations are unavoidable. In order to overcome these problems, the paper proposes reasonable and general algorithms based on the standard model system and proper criterion, which offers the fair and objective evaluations in any case. The proposed algorithms are divided by two main themes. One is an optimal algorithm for the voltage control of multiple voltage regulators in order to deliver suitable voltage to as many customers as possible, and the other is a proper evaluation algorithm for the voltage management at normal and emergency conditions. The results from a case study show that the proposed methods can be a practical tool for the voltage management in distribution systems including dispersed sources.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.17 no.7
• /
• pp.1660-1671
• /
• 2013

In this paper two types of power management circuits for solar energy harvesting self-powered systems are proposed. First, if the output voltage of a solar cell is enough to drive load, a power management unit(PMU) directly supplies load with solar energy. Second, if a solar cell outputs very low voltage less than 0.5V as in miniature solar cells or monolithic integrated solar cells such that it cannot directly power the load, a voltage booster is employed to step up the solar cell's output voltage, and then PMU delivers the boosted voltage to the load. The proposed power management systems are designed and fabricated in a $0.18{\mu}m$ CMOS process, and their performances are compared and analyzed through measurements.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.29 no.7
• /
• pp.28-37
• /
• 2015

Owing to the variability of large-scaled wind power system, the development of wind farm management technologies and related compensation methods have been receiving attention. To provide an accurate and reliable output power, certain wind farm adopts a specified management system including a wind prediction model and grid expectation solutions for considering grid condition. Those technologies are focused on improving the reliability and stability issues of wind farms, which can affect not only nearby system devices but also a voltage condition of utility grid. Therefore, to adapt the develop management system, an expectation process about voltage condition of Point of Common Coupling should be integrated in operating system for responding system requirements in real-time basis. This paper introduce a grid imposing method for a real-time based wind farm management system. The expected power can be transferred to the power flow section and the required quantity about reactive power can be calculated through the proposed system. For the verification process, the gauss-seidel method is introduced in the Matlab/Simulink for analysing power flow condition. The entire simulation process was designed to interwork with PSCAD for verifying real power system condition.

• Journal of Advanced Engineering and Technology
• /
• v.5 no.4
• /
• pp.349-353
• /
• 2012

Recently, Mobile multimedia equipments as smart phone and tablet pc requirement is increasing and this market is also being expanded. These mobile equipments require large multi-media function, so more power consumption is required. For these reasons, the needs of power management IC as switching type dc-dc converter and linear regulator have increased. DC-DC buck converter become more important in power management IC because the operating voltage of VLSI system is very low comparing to lithium-ion battery voltage. There are many people to be concerned about digital DC-DC converter without using external passive device recently. Digital controlled DC-DC converter is essential in mobile application to various external circumstance. This paper proposes the DC-DC Buck Converter using the AVR RISC 8-bit micro-processor control. The designed converter receives the input DC 18-30 [V] and the output voltage of DC-DC Converter changes by the feedback circuit using the A/D conversion function. Duty ratio is adjusted to maintain a constant output voltage 12 [V]. Proposed converter using the micro-processor control was compared to a typical boost converter. As a result, the current loss in the proposed converter was reduced about 10.7%. Input voltage and output voltage can be displayed on the LCD display to see the status of the operation.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.56 no.10
• /
• pp.1757-1762
• /
• 2007

Recently, the demand for the low cost power conversion equipment is rapidly increased. To develop this three phase voltage source inverter, optimum power conversion equipment to system is designed. The optimum operation method to minimize the power loss also satisfy the life time of the power electronics that is request in the present industry. In this paper, the efficient operating method to change of the acceleration, jerk, and switching frequency in the interval of acceleration is selected to optimize the power loss and life time of the power electronics by using the elevator model. So, we proposed the method that 50[A] rating power electronics is adopted in 9[kW] load.

• Proceedings of the Safety Management and Science Conference
• /
• 2001.05a
• /
• pp.67-75
• /
• 2001

Circuitry to be connected to a Telecommunication Network consists of SELV CIRCUITS or TNV CIRCUITS. So International Standards, like as ITU-T Recommendation K.11, UL 1950, CSA C22.2 950 have been taken to reduce the risk that the Overvoltages from the power lines and from electrictraction lines, that may be received from the telecommunication network. Legal requirements may exist regarding permission to connect equipment having PTC components to a telecommunication network. Surge suppressors that bridge the insulation shall have a minimum d.c. sparkover voltage of 1.6 times the rated voltage or 1.6 times the upper voltage of the tared voltage range of the equipment. If left in place during electric strength testing of insulation, they shall not be damaged. In this work, The Conception ＆ Fail-Mode Analysis of PTC components for Over-Current Protection is proposed. It guarantees the protection for PL Claim about this Subject.

• ETRI Journal
• /
• v.33 no.3
• /
• pp.407-414
• /
• 2011

In an effort to reduce energy consumption, research into adaptive power management in real-time systems has become widespread. In this paper, a novel dynamic voltage scaling scheme is proposed for multiprocessor systems. Based on the concept of the Nash bargaining solution, a processor's clock speed and supply voltage are dynamically adjusted to satisfy these conflicting performance metrics. In addition, the proposed algorithm is implemented to react adaptively to the current system conditions by using an adaptive online approach. Simulation results clearly indicate that the superior performance of the proposed scheme can strike the appropriate performance balance between contradictory requirements.

• Proceedings of the KIEE Conference
• /
• 2005.07e
• /
• pp.100-102
• /
• 2005

This paper is purpose to introduce the database management program of insulation tests for high voltage rotating machines. KEPRI has carried out insulation tests for high voltage equipment since 1998, the number of tests grow larger every year. It is difficult to manage the numerous test results, so we developed the insulation diagnostic database program. The features of this program are an easy-search test result and making a graph of AC, tan${\Delta}$ test. the most useful function is the trend management. Using the trend function, we can find the aging deterioration for high voltage machines easily.

• Journal of Information Processing Systems
• /
• v.7 no.4
• /
• pp.613-626
• /
• 2011

In this paper, we focus on the pinwheel task model with a variable voltage processor with d discrete voltage/speed levels. We propose an intra-task DVS algorithm, which constructs a minimum energy schedule for k tasks in O(d+k log k) time We also give an inter-task DVS algorithm with O(d+n log n) time, where n denotes the number of jobs. Previous approaches solve this problem by generating a canonical schedule beforehand and adjusting the tasks' speed in O(dn log n) or O($n^3$) time. However, the length of a canonical schedule depends on the hyper period of those task periods and is of exponential length in general. In our approach, the tasks with arbitrary periods are first transformed into harmonic periods and then profile their key features. Afterward, an optimal discrete voltage schedule can be computed directly from those features.