The Effect of Transformer Leakage Inductance on the Steady State Performance of Push-pull based Converter with Continuous Current Qian Chen†, Trillion Q. Zheng*, Yan Li*, and Tiancong Shao*

The Effect of Transformer Leakage Inductance on the Steady State Performance of Push-pull based Converter with Continuous Current Qian Chen†, Trillion Q. Zheng*, Yan Li*, and Tiancong Shao* †*School of Electrical and Engineering, Beijing Jiaotong University, Beijing, China Abstract As a result of the advantages such as high efficiency, continuous current and high stability margin, push-pull converter with continuous current (PPCWCC) is competitive for battery discharge regulator (BDR) which plays an important role in power conditioning unit (PCU).Leakage inductance yields current spike in low-ripple current of PPCWCCs. The operating modes are added due to leakage inductance. Therefore the steady state performance is affected, which is embodied in the spike of low-ripple current. PPCWCCs which are suitable for BDR can be separated into three types by current spike characteristics. Three representative topologies IIs1, IIcb2 and Is3 are analyzed in order to investigate the factors on the magnitude and duration of spike. Equivalent current sampling method (ECSM) which eliminates the sampling time delay and achieves excellent dynamic performance is adopted to prevent the spike disturbance on current sampling. However, ECSM reduces the sampling accuracy and telemetry accuracy due to neglecting the spike. In this paper, ECSM used in PPCWCCs is summarized. The current sampling error is analyzed in quality and quantity, which provides the foundation for offsetting and enhancing the telemetry accuracy. Finally, current sampling error rate of three topologies is compared by experiment results, which verify the theoretical analysis.
LINK
http://jpe.or.kr/archives/view_articles.asp?seq=735

Design of an LCL-Filter for Three-Parallel Operation of Power Converters in Wind Turbines Hae-Gwang Jeong*, Dong-Keun Yoon**, and Kyo-Beum Lee†

Design of an LCL-Filter for Three-Parallel Operation
of Power Converters in Wind Turbines
Hae-Gwang Jeong*, Dong-Keun Yoon**, and Kyo-Beum Lee†
†*Department of Electrical and Computer Engineering, Ajou University, Suwon, Korea
**Research Group, LG Innotek Co., Ltd., Ansan, Korea

This paper proposes a design scheme for an LCL-filter used for the three-parallel operation of the power converters in high-capacity wind turbines. The designs of the power devices and grid connected filter are difficult due to the high level voltages and currents in huge-capacity wind turbines. To solve these problem, this paper presents three-parallel operation and LCL-filter design techniques optimized by parallel operation. Furthermore, the design of an inverter side inductance of the LCL-filter is discussed in detail considering the switching modulation method. Simulation and experimental results demonstrate the validity of the designed filter and wind turbines.
LINK
http://jpe.or.kr/archives/view_articles.asp?seq=744
https://www.mediafire.com/?f2tlal6acrdao3a

GRAU DE PROTEÇÃO IP PARA EQUIPAMENTOS ELÉTRICOS

Parallel Operation of Three-Phase Four wire UPS using Droop Control ( Hyunseob Kim․Jungho Han․Joong-Ho Song )

Parallel Operation of Three-Phase Four wire UPS using Droop Control

* Main author：Dept. of Railway Electrical and
Signaling Engineering, Seoul National
University of Science and Technology,
Candidate of MS
** Corresponding author：Dept. of Electrical and
Information Engineering, Seoul National
University of Science and Technology,
Professor
Tel：02-970-6415, Fax：02-978-2754
E-mail：joongho@seoultech.ac.kr
 Abstract
A new droop control method which can be applied to 3-phase 4-wire uninterruptible power supply is
proposed in this paper. The droop control method for parallel operation is very attractive one as UPS
parallel operation can be carried out without any data communication devices provided among UPS
systems connected, but it reportedly shows a PnP(plug-and-play) problem. A basic reason why a
circulating current could flow among parallel-connected UPS systems is clearly investigated as well
when droop-controlled-ups systems are operated in the manner of PnP. The proposed algorithm is
deduced from the investigated result and is basically structured to keep a balanced frequency and
balanced voltage profile against power variation. This paper shows that balanced parallel operation of
droop control method can be obtained under unbalanced load as well as balanced load conditions .when PnP operation is needed and load change occurs.
LINK
http://www.koreascience.or.kr/article/ArticleFullRecord.jsp?cn=JMJGCE_2013_v27n4_88

https://www.mediafire.com/?gyedgrq3fd38alx

Power Factor Correction of Single-phase Boost Converter for Low-cost Type UPS Configuration Jong-Chan Park․Jin-Geun Shon

Power Factor Correction of Single-phase Boost Converter for Low-cost Type UPS Configuration 박 종 찬*․손 진 근† (Jong-Chan Park․Jin-Geun Shon) The Transactions of the Korean Institute of Electrical Engineers Vol. 62P, No. 3, pp. 145～150, 2013

 Abstract -A novel AC to DC PWM converters with unity input power factor are proposed to overcome the above shortcoming. The main function of these converters is to shape the input line current to force it exactly in phase with the input AC voltage. Therefore, the input power factor can be improved to near unity and the input current harmonics can be eliminated. In this paper, half-bridge converter with two active switches and two diodes are utilized for low-cost type UPS configuration. By having only two semiconductors in the current path at any time, losses can be reduced over the conventional boost topology. Also, this converter provides controllable dc-link voltage, high power factor, and low cost type converter by simple power circuits. Simulation results show that the proposed half-bridge converter/inverter control technique can be applied to single-phase low-cost type UPS systems successfully.
LINK
http://www.koreascience.or.kr/article/ArticleFullRecord.jsp?cn=DHJGHA_2013_v62n3_145

https://www.mediafire.com/?fqu14xattw5nwkp

LLC Resonant Converter design for Uninterruptible Power Supply Battery Discharger

LLC Resonant Converter design for Uninterruptible Power Supply Battery
Discharger
Kwang-Min Yoo1, Seung-Joo Kim1, Kyoung-Dong Kim1, Seung-Hee Park1, Yong-Seop Byeon,
Seung-Beom Lim, and Jun-Young Lee

Abstract - An Uninterruptible Power Supply(UPS) is a system designed to deliver energy during accidents that the AC mains is out of its acceptable limits, without interruption of power flow through the load. Battery Discharger is the device to supply high quality power to the Inverter, when accidents occur, such as Power Failure. The Battery Discharger should have a fast response characteristics. The LLC resonant converter for UPS battery discharger is proposed. The proposed Battery Discharger offers substantial improvements in efficiency, size and cost. The proposed Battery Discharger of UPS approach is a good solution for high power applications above KW. To verify the validity of proposed Battery Discharger, simulations and experiments are carried out. Paper number: TKPE-2013-18-3-6 ISSN: 1229-2214 ✝ Corresponding author: pdpljy@mju.ac.kr, Dept. of Electrical Engineering, MyongJi University Tel: +82-31-330-6357 Fax: +82-31-330-6977 1 Dept. of Electrical Engineering, Myongji University 2 Eon Co., Ltd Manuscript received Oct. 5, 2012; accepted Feb. 20, 2013 ─ 본 논문은 2012년 전력전자학술대회 외부장학금 수혜논문임
DOWNLOAD
 http://www.koreascience.or.kr/article/ArticleFullRecord.jsp?cn=JRJJC3_2013_v18n3_240

https://www.mediafire.com/?143thdj9xfgg61s

A Controller Design for a Stability Improvement of an On-Board Battery Charger Hae-Gwang Jeong* and Kyo-Beum Lee†

A Controller Design for a Stability Improvement of an On-Board
Battery Charger
Hae-Gwang Jeong* and Kyo-Beum Lee†
Corresponding Author: Department of Electrical and Computer
Engineering, Ajou University, Suwon, Korea. (kyl@ajou.ac.kr)
* Dept. of Electrical and Computer Engineering, Ajou University,
Suwon, Korea. (lite88@ajou.ac.kr)
Received: May 27, 2013; Accepted: June 7, 2013

Abstract – This paper proposes the controller design for a stability improvement of an on-board
battery charger. The system is comprised of a power factor correction (PFC) circuit and phase shift
full-bridge DC-DC converter. The PFC circuit performs the control of the DC-link voltage and the
input power factor. The DC-DC converter regulates the voltage and the current in the battery using the
DC-link voltage. This paper proposes the design method of PI controller for the PFC circuit using a
small signal model. The analysis and design of a type-three controller for the DC-DC converter is also
presented. A simulation and experiment has been performed on the on-board battery charger and their
results are presented to verify the validity of the proposed system.
DOWNLOAD
http://www.koreascience.or.kr/article/ArticleFullRecord.jsp?cn=E1EEFQ_2013_v8n4_951

https://www.mediafire.com/?b466cwi2g7t404z

A Three-Phase High Frequency Semi-Controlled Battery Charging Power Converter for Plug-In Hybrid Electric Vehicles

A Three-Phase High Frequency Semi-Controlled
Battery Charging Power Converter for Plug-In
Hybrid Electric Vehicles
Mahmoud M. Amin and Osama A. Mohammed†
† Dept. of Electrical and Computer Eng., Florida International University, Florida, United States
Abstract
This paper presents a novel analysis, design, and implementation of a battery charging three-phase high frequency semicontrolled
power converter feasible for plug-in hybrid electric vehicles. The main advantages of the proposed topology include
high efficiency; due to lower power losses and reduced number of switching elements, high output power density realization, and
reduced passive component ratings proportionally to the frequency. Additional advantages also include grid economic utilization
by insuring unity power factor operation under different possible conditions and robustness since short-circuit through a leg is not
possible. A high but acceptable total harmonic distortion of the generator currents is introduced in the proposed topology which
can be viewed as a minor disadvantage when compared to traditional boost rectifiers. A hysteresis control algorithm is proposed
to achieve lower current harmonic distortion for the rectifier operation. The rectifier topology concept, the principle of operation,
and control scheme are presented. Additionally, a dc-dc converter is also employed in the rectifier-battery connection. Test results
on 50-kHz power converter system are presented and discussed to confirm the effectiveness of the proposed topology for PHEV
applications.
LINK DOWNLOAD
http://www.koreascience.or.kr/article/ArticleFullRecord.jsp?cn=E1PWAX_2011_v11n4_490

A Study on the Hot Spot Temperature in 154kV Power Transformers Dong-Jin Kweon†, Kyo-Sun Koo*, Jung-Wook Woo* and Joo-Sik Kwak*

A Study on the Hot Spot Temperature in 154kV Power Transformers
Dong-Jin Kweon†, Kyo-Sun Koo*, Jung-Wook Woo* and Joo-Sik Kwak*
Abstract – The life of a power transformer is dependent on the life of the cellulose paper, which
influenced by the hot spot temperature. Thus, the determination of the cellulose paper’s life requires
identifying the hot spot temperature of the transformer. Currently, however, the power transformer
uses a heat run test is used in the factory test to measure top liquid temperature rise and average
winding temperature rise, which is specified in its specification. The hot spot temperature is calculated
by the winding resistance detected during the heat run test. This paper measures the hot spot
temperature in the single-phase, 154kV, 15/20MVA power transformer by the optical fiber sensors and
compares the value with the hot spot temperature calculated by the conventional heat run test in the
factory test. To measure the hot spot temperature, ten optical fiber sensors were installed on both the
high and low voltage winding; and the temperature distribution during the heat run test, three
thermocouples were installed. The hot spot temperature shown in the heat run test was 92.6℃ on the
low voltage winding. However, the hot spot temperature as measured by the optical fiber sensor
appeared between turn 2 and turn 3 on the upper side of the low voltage winding, recording 105.9℃.
The hot spot temperature of the low voltage winding as measured by the optical fiber sensor was 13.3℃
higher than the hot spot temperature calculated by the heat run test. Therefore, the hot spot factor (H)
in IEC 60076-2 appeared to be 2.0.
LINKS DOWNLOAD
http://www.koreascience.or.kr/article/ArticleFullRecord.jsp?cn=E1EEFQ_2012_v7n3_312

https://www.mediafire.com/?skoajdlchdtoj0c

Implementation of a High Efficiency Grid-Tied Multi-Level Photovoltaic Power Conditioning System Using Phase Shifted H-Bridge Modules

Implementation of a High Efficiency Grid-Tied
Multi-Level Photovoltaic Power Conditioning
System Using Phase Shifted H-Bridge Modules
Jong-Pil Lee†, Byung-Duk Min**, and Dong-Wook Yoo*
†*Power Conversion Research Center, Korea Electrotechnology Research Institute, Changwon, Korea
**Green Power Co. Ltd, Suwon, Korea
Abstract
This paper proposes a high efficiency three-phase cascaded phase shifted H-bridge multi-level inverter without DC/DC
converters for grid-tied multi string photovoltaic (PV) applications. The cascaded H-bridge topology is suitable for PV
applications since each PV module can act as a separate DC source for each cascaded H-bridge module. The proposed phase
shifted H-bridge multi-level topology offers advantages such as operation at a lower switching frequency and a lower current
ripple when compared to conventional two level topologies. It is also shown that low ripple sinusoidal current waveforms are
generated with a unity power factor. The control algorithm permits the independent control of each DC link voltage with a
maximum power point for each string of PV modules. The use of the controller area network (CAN) communication protocol for
H-bridge multi-level inverters, along with localized PWM generation and PV voltage regulation are implemented. It is also
shown that the expansion and modularization capabilities of the H-bridge modules are improved since the individual inverter
modules operate more independently. The proposed topology is implemented for a three phase 240kW multi-level PV power
conditioning system (PCS) which has 40kW H-bridge modules. The experimental results show that the proposed topology has good performance.
LINKS DOWNLOAD
http://www.koreascience.or.kr/article/ArticleFullRecord.jsp?cn=E1PWAX_2013_v13n2_296