Design of an LCL-Filter for the Three-Parallel Operation of a Power Converter in Wind Turbines DONG-KEUN YOON AJOU UNIVERSITY

Permanent Magnet Synchronous Generators (PMSG) are widely used in variable-speed wind turbines. However, the power devices must support high currents to get their high-power rating because the PMSG is connected directly to the grid through a back-to-back converter. Therefore, the rated current of the power device can be reduced to one third of the rated value by using a three-parallel operation. The low switching frequency of a high power system may cause an increase in the harmonics found in the output current.
This paper proposes a design scheme for an LCL-filter used for three-parallel operation of a power converter in 2MW-wind turbines. An appropriate design method of the delta configured LCL-filter is also proposed to improve the output power quality in the system. A novel design method for the inner inductance of the LCL-filter is proposed in order to overcome the existing trial and error methods used in designing the filter. LCL-filters typically have a problem with a reduced power factor (PF), due to the capacitor used. To improve the poor PF, a simple compensation method is also proposed. The simulation and experimental results demonstrate that the grid current harmonics are low and the PF is improved.

Research on High Efficiency Non-Isolated Push-Pull Converters with Continuous Current in Solar-Battery Systems Yan Li, Trillion Q. Zheng, and Qian Chen

Research on High Efficiency Non-Isolated Push-Pull Converters with Continuous Current in Solar-Battery SystemsYan Li, Trillion Q. Zheng, and Qian Chen
Abstract
 In order to improve the output efficiency of solar cells and to extend the life span of batteries, the input currents of converters are required to be continuous. If low output voltage ripple is required at the same time, it is obvious that the application of basic two-order converters (such as Buck and Boost derived converters) will not be good enough. In this paper, a lot of non-isolated push-pull converters (NIPPCs) with continuous current will be introduced due to their lower current stress, higher efficiency and better EMC performance. By decomposing the converters into push-pull cells, inductor and free-wheeling diodes, two families of NIPPCs based on single inductor and coupled inductor separately are systematically generated. Furthermore, characteristics analyses for some of the generated converters are also shown in this paper. Finally, two prototypes based on the corresponding typical topologies are built in the lab to verify the theoretical outcomes.
LINK
http://jpe.or.kr/archives/view_articles.asp?seq=852

A Novel Circuit Configuration of UPS with Auxiliary Inverter and Its Specific Control Implementations Katsuya Hirachi and Mutsuo Nakaoka

A Novel Circuit Configuration of UPS with Auxiliary Inverter and Its Specific Control Implementations
Katsuya Hirachi and Mutsuo Nakaoka
RESEARCH AND DEVELOPMENT DIVISION POWER SUPPLY  COMPANY,YUASA,OSAKA JAPAN.
DEPT. OF ELECTRICAL AND ELECTRONICS ENGINEERING  YAMAGUCHI UNIVERSITY
YAMAGUCHI JAPAN

Abstract
 The rapid expansion of small computers over the last 10-odd years has brought about great changes in the circumstances affecting UPSs. There are strong demands that UPSs become much smaller and lighter, and more economical, which has resulted in the wide application of the circuit topology without transformer. A disadvantage of such UPS topology is that the DC link voltage is very high, which invites decreased reliability and increased cost of battery bank. Some circuit configurations were proposed to eliminate this disadvantage, but they still had problems. In this paper, a novel circuit configuration which eliminates these problems is proposed and evaluated by the experimental results of prototype UPS.
LINK
http://jpe.or.kr/archives/view_articles.asp?seq=79
LINK DIRECT
http://manuscript.jpe.or.kr/ltkPSWeb/pub/pubfpfile.aspx?ppseq=79

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
application.
LINK ORIGINAL
http://jpe.or.kr/archives/view_articles.asp?seq=536
LINK DIRECT
http://manuscript.jpe.or.kr/ltkPSWeb/pub/pubfpfile.aspx?ppseq=536

Reduction of Total Harmonic Distortion in Inverters Driving a Compressor using Active Power Filter with Phase Delay Compensation

Reduction of Total Harmonic Distortion in Inverters Driving a Compressor
using Active Power Filter with Phase Delay Compensation
Lim,Chan-Gyu
School of Electronics Engineering, Major in Control System
Graduate School, Kyungpook National University Daegu, Korea
(Supervised by Professor Choi, Jong-Woo)

ABSTRACT
 In recent years, there has been a considerable interest in the active power filters and power quality contaminated by non-linear load. Among the power filters, a shunt active filter is most preferable to protect the consumers from the power line with an harmonic load current. This paper describes the active power filter to comply with harmonics current regulation(IEC 61000-3-12) effective for the inverter air-conditioners whose operating current is more than 16A. The validity of the proposed compensating method has been verified by the experimental results for a shunt active power filter controlled by all pass filter to compensate a phase delay of harmonics. It was shown that the total harmonic distortion (THD) of the air-conditioner inverter has been much reduced to 6% from 54%. It is expected that the proposed active power filter is effective to the competitiveness of the air-conditioner inverter and the reduction of harmonic damage such as power line loss, power device overheating.
 A thesis submitted to the Council of the Graduate School of Kyungpook National University in partial fulfillment of the requirements for the degree of Master of Science. in December, 2013.
LINK
http://www.mediafire.com/view/9d091coag56oxx6/FILTRO_ACTIVO_AR_CONDICIONADO.pdf