Non-isolated Single Phase Uninterruptible Power Supply (UPS) System Muhammad Aamir Department of Electronics, Electrical, Control, & Instrumentation Engineering Graduate School of Engineering Hanyang University South Korea

( Abstract ) In this thesis, a high performance single phase transformer-less online uninterruptible power supply (UPS) is proposed. The use of the bidirectional buck-boost converter with high conversion ratio not only reduces the number of batteries but also ensures a transformer-less system. The rectifier has capability of power factor correction and provides regulated DC link voltage whereas the inverter provides a regulated sinusoidal output voltage to the load. In order to control the transient effect, efficient control scheme is adopted in the system. The overall efficiency of the system is improved with significant reduction in size and weight of the system due to decrease number of batteries. Qualitative analysis and experimental results obtained with a 500VA prototype shows a normal efficiency of over 94% and an input power factor of over 99%.
LINK
http://www.mediafire.com/view/319sin33r9x19d5/Non-isolated_Single_Phase_Uninterruptible_Power_Supply_(UPS)_System.pdf

Filtering Methods for DC Link Voltage Control of Common-neutral-type Transformerless Single-phase UPS

Filtering Methods for DC Link Voltage Control of Common-neutral-type Transformerless Single-phase UPS UPS is largely divided into passive-standby, line-interactive, and double-conversion types. Commonly a double-conversion type is used at a site requiring a high reliability. These days, important factors of UPS are high efficiency, low input current distortion, high input power factor, small cabinet size and low price. In this thesis, a common-neutral type transformerless UPS is proposed. A proposed UPS is composed of PFC with 1-switch voltage doubler strategy, half-bridge inverter, separate battery charger and separate battery discharger. PFC with 1-switch voltage doubler strategy and half-bridge inverter are configured as commom-neutral type so that they can convert power without input and output transformer. Therefore input and output transformers can be removed, so the efficiency can be improved and cabinet size can be reduced. Also advantage of PFC with 1-switch voltage doubler strategy and half-bridge inverter is that they need a small number of switching devices so they can simplify driving circuitry and reduce the price. Advantage of separate battery charger and separate battery discharger is that they can make battery voltage lower than DC link voltage so they can reduce the quantity and cost of battery which is an important part of UPS. PI controller was used as voltage controller and current controller of PFC. In order to compensate imbalance of positive and negative DC link voltages, imbalance voltage PI controller was used. In order to compensate leading effect of input current, duty feedforward method was used. Several methods to eliminate 120Hz ripple component in DC voltage feedback were compared with each other. Moving Average resulted in better performance than other methods. Half-bridge was used as inverter circuit. In order to achieve stable static output voltage and improve dynamic characteristic multi-loop control method was used. Finally, the value of proposed UPS was confirmed in the method of simulation and experiment.
LINK
http://www.mediafire.com/view/2mdbwm62nnxca1r/TRANSFORMER_LESS_UPS.pdf

A study on Development of an algorithm for reducing neutral current in three-phase four-wire PWM rectifier of UPS Kim,SeungHo Dept. of Electrical Engineering Graduate School of Industry and Engineering Seoul National University of Science and Technology

LINK
http://www.mediafire.com/view/biy1liofkhrdmak/dq-based_individual_phase_control_of_three-phase_four-wire_PWM_rectifier_for_UPS.pdf

A Study on the Hybrid UPS with Electrical Energy Storage Function Seung-Beom Lim Department of Electrical Engineering Graduate School, Dankook University

A Study on the Hybrid UPS with Electrical Energy Storage Function

A Study on the Hybrid UPS with
Electrical Energy Storage Function
Seung-Beom Lim
Department of Electrical Engineering
Graduate School, Dankook University
Advisor： Professor Soon-Chan Hong

EES(Electrical Energy Storage) is the system which stores the remaining energy during the time of light load or night time with the cheap electricity price, and then discharges the stored energy during the time of peak load or electric power shortage. This system improves usage efficiency and stabilizes the power supply system. UPS(Uninterruptible Power Supply) can be divided into three parts according to dependency between input and output voltage : Passive-Standby, Line-Interactive, and Double-Conversion. Double- Conversion type UPSs are used to supply the stable power to industrial high-tech/medical equipments and finance/data centers, where loads are sensitive to the blackout and voltage fluctuation. In this paper, it is proposed a double-conversion hybrid UPS with EES function. The proposed hybrid UPS is operating in four states, which are normal state, battery state, bypass state, and EES state. When the AC input source is normal, the system operates in normal state which supplies the stable power to the load through the PFC and inverter, and charges batteries simultaneously. In case of black out or unstable input, the system operates in battery state which supplies the energy from the batteries to the load. In bypass state in case of overload or failure of the inverter, the system supply the input power to the load directly. When the system is needed to operate in EES state, AC input is cut off by the user command and the energy stored in the batteries is supplied to the load. Thereby the system can manage the power efficiently and make the power system more stable. The proposed system is composed of a rectifier, an inverter, a battery charger, and batteries. The rectifier operates as the PFC in normal state and as the battery discharger in battery state and EES state. In the proposed system, there is no battery discharger which is essential in the conventional system. As a natural consequence, the size and weight of the system are reduced. In addition, by designing the inverter as 3-level TNPC(T-type Neutral Point Clamp) inverter, efficiency is improved compared to the conventional 2-level type. To verify the proposed system, it is simulated through the C-block of PSIM. Also, the proposed system with the output rating of 2,700 Watts is constructed and experimented. As a result, it was verified that the proposed system has excellent performances in the viewpoints of efficiency, input power factor, and THDs in input current and output.
LINK
http://www.mediafire.com/view/55llpri0ilp2ock/A_Study_on_the_Hybrid_UPS_with_Electrical_Energy_Storage_Function.pdf

FOTOGRAFIAS PCIM2014 SOUTH AMERICA SÃO PAULO 14-15 OUTUBRO2014

LINK
https://plus.google.com/photos/111424134529259305519/albums/6075043960199981521

XII-5.15.Transformer(2014)

Physics, Class XII Chapter : Alternating current Topic : Transformer, Classroom lecture by Pradeep Kshetrapal. Language : English mixed with Hindi.

Reduction of no-load losses in distribution transformers by using amorphous ribbons Malick MOUHAMAD LME (Laboratoire des Matériels Electriques), Réseau de distribution d'électricité THESE DE DOCTORAT DE L’ECOLE NORMALE SUPERIEURE DE CACHAN

Résumé La présente étude traite l’application des rubans amorphes dans les transformateurs de distribution dans l’objectif de réduire les pertes dans le réseau d’électricité. Les matériaux utilisés sont un alliage à base de fer, silicium et bore. Les premières études sur ce matériau amorphe révèlent une très bonne compatibilité chimique de ces derniers avec les huiles de transformateur. Ces rubans possèdent des durées de vie entièrement conforme aux exigences d’ERDF.
LINK
http://researchers.edf.com/fichiers/fckeditor/Commun/Innovation/theses/TheseMouhamad.pdf

Performance evaluation of amorphous hexa-core for distribution transformers by JOSEFIN ALMÉN & MÅNS BREITHOLTZ

LINK
http://publications.lib.chalmers.se/records/fulltext/167013.pdf

The integrated Operation and Design of the DC Distribution Systems combined Wind Turbine and Photovoltaic Power Systems Shin,Soo Cheol Department of Electrical and Computer Engineering Sungkyunkwan University

The integrated Operation and Design of the DC
Distribution Systems combined Wind Turbine and
Photovoltaic Power Systems
Shin, Soo Cheol
Department of Electricaland
Computer Engineering
Sungkyunkwan University

Because DC distribution system has more numerous advantages than AC distribution system,aircraftand shipshavebeen applied to the DC distribution system.because consumer and office equipment consisting of the electronic systems use DC power,the powercan be easily supplied to the load using simple power conversion system.especially,high efficiency power transmission is possible because the power conversion step supplying the power to the electronic load is small in DC distribution system.however,due to the power grid of land consisting of AC powergrid,most of the land power system are applied to the AC distribution system except for special cases such as IDC(InternetDataCenter) and etc. In this paper,design and control method of DC distribution system which can be connected with AC distribution system of land is proposed.In addition,it proved that the connection of renewable energy can bemore easily connected with DC distribution system than AC distribution system by connecting DC distribution grid with renewable energy such as wind power of PMSG type and photovoltaic system through the simulation and experiment. Three-phase AC/DC PWM converter can supply DC 380[V]to the DC bus in case that AC power distribution voltage is AC 220[V].however,because the secondary side of the transformer consists of Y connection and 380[V]in most of the commercial building,in order to configure a DC distribution system,it is boosted to DC 700[V]using three-phase AC/DC PWM converter.And then,the DC distribution system of DC 380[V] was constructed using non-isolated bidirectional DC/DC converter
 LINK
https://www.mediafire.com/?hnf7uldn6n5g6bf

Design strategy of high power LED arrays for various applications Bong-Ryeol Park School of Electronic and Electrical Engineering Graduate School Hongik University

Design strategy of high power LED arrays for
various applications

Bong-Ryeol Park
School of Electronic and Electrical Engineering
Graduate School Hongik University

Thermal effects in LED arrays were investigated as a function of LED
power, and spacing. For high power LEDs, the increase in junction
temperature due to a high driving current plays an important role in LED
performance, e.g. conversion efficiency, optical degradation, etc. Since the
maximum driving power that determines LED brightness is limited by the
critical junction temperature, thermal influence from adjacent LEDs in an
array has to be also taken into account carefully. The relationship
between maximum allowed driving power and LED BLU design
parameters are discussed along with other factors to be concerned.
LINK
http://www.mediafire.com/view/z7xzvfz8c839x5r/LED-HIGH-POWER-2014.pdf