i-manager's Journal on Circuits and Systems (JCIR)


Volume 4 Issue 4 September - November 2016

Research Paper

SRAM Write Operation Using Write Assist Circuit Technique at Low Supply Voltages

A. Pulla Reddy* , G.Sreenivasulu**, R. Veerabadra Chary***
* Research Scholar, Department of Electronics and Communication Engineering, SVU College of Engineering, Tirupati, India.
** Professor, Department of Electronics and Communication Engineering, SVU College of Engineering, Tirupati, India.
*** Senior Manager, Invecas Ltd., India.
Reddy, P. A., Sreenivasulu, G., and chary, R.V. (2016). SRAM Write Operation Using Write Assist Circuit Technique at Low Supply Voltages. i-manager’s Journal on Circuits and Systems, 4(4), 1-5. https://doi.org/10.26634/jcir.4.4.12392

Abstract

The increased effect of process variation and increase in parasitic resistance and capacitance in nano scale technologies at lower supply voltages, and continuous increase in the size of SRAMs require additional techniques, such as write assist and read assist to improve the write-ability, readability, and stability of SRAM memories. The SRAM bit cell write-ability is very critical at lower voltages. The impact of the write assist technique is analysed in this paper which will improve the write-ability of the SRAM memory and also its impact on the performance, power, and area of the chip. The Negative Bit-line Voltage Bias scheme is discussed and executed at the transistor level using conventional SRAM cell (6T). With the write assist circuit, the implemented SRAM bit cell efficiently performs a write operation at lower voltages. The main objective of this paper is to improve the write-ability of the SRAM cell at lower supply voltage using Negative Bit-line Write Assist Circuit.

Research Paper

Fuzzy Logic Controller for Three Phase Neutral Point Clamped Inverter with PV System

Romi Choudhary* , A.N. Tiwari**
* PG Scholar, Department of Power Electronic and Drives Engineering from Madan Mohan Malaviya University, Gorakhpur, India.
** Associate Professor, Department of Electrical Engineering, Madan Mohan Malaviya University of Technology, Gorakhpur, India.
Choudhary, R., and Tiwari, A.N. (2016). Fuzzy Logic Controller for Three Phase Neutral Point Clamped Inverter with PV System. i-manager’s Journal on Circuits and Systems, 4(4), 6-11. https://doi.org/10.26634/jcir.4.4.12393

Abstract

The main contribution of the paper is the proposal of Fuzzy Logic Controller (FLC) for three phase transformerless neutral point clamped inverters to eliminate harmonics in photovoltaic systems without requiring any modification on the multilevel inverter or any additional hardware. Multilevel level inverter technology has been widely used in the high power Medium voltage energy control systems [1]. In this paper, the authors have proposed a Fuzzy Logic Controller for three phase neutral point clamped inverter with PV system. They have used the neutral point clamped inverter in this paper because NPC inverter results in the low frequency voltage harmonics in the NP, which is the point between the two DC-link capacitors [7]. In primary side, PV system eliminates the harmonics by using the FLC, and the voltage controller is to produce regulated output voltage with low distortions under all loading conditions. A Fuzzy Logic Controller is developed by using MATLAB/SIMULINK for the chosen inverter having applications in the PV system. FLC is found to have better performance. This paper presents a methodology to generate gating signal to control NPCVSI using MATLAB/SIMULINK.

Research Paper

Performance Analysis of Wind Energy Conversion System Employing DFIG

G. Pandu Ranga Reddy* , M. Vijaya Kumar**
* Associate Professor, Department of Electrical Engineering, G. Pullaiah College of Engineering and Technology, Kurnool, Andhra Pradesh, India.
** Professor, Department of Electrical Engineering, Jawaharlal Nehru Technological University Anantapur, Anantapuramu, Andhra Pradesh, India.
Reddy, G. P. R., and Kumar, M.V. (2016). Performance Analysis of Wind Energy Conversion System Employing DFIG. i-manager’s Journal on Circuits and Systems, 4(4), 12-18. https://doi.org/10.26634/jcir.4.4.12394

Abstract

In the socio-economic development, the requirement of energy is considered as the most essential element. Renewable energy sources can play an enormous role to fulfill this need of energy. These sources will not only improve independency of energy, but also help in many ways, such as mitigation of climate change, swift development of rural areas, improved health status, and will be the best way to move towards sustainable development. Among all the renewable energy sources, the wind energy plays a key role to reduce fossil fuels dependency and acts as a helpful tool to conflict global warming. Wind energy is indeed a form of solar energy produced by differential heating on the earth surface. Wind's kinetic energy can be captured and converted into electricity via wind turbines. This paper presents the analysis of wind energy conversion system employing DFIG when it is connected to the grid. The Back to Back Voltage Source Converter is used for converting the unregulated generated AC into regulated AC. The sinusoidal pulse width modulation technique is used for generating the control pulses to the converter

Research Paper

An Enhancement of power quality by using fuzzy logic controller for typical household applications

A.Purushotham* , Vishnuvardhan**
* PG Scholar, Department of Electrical and Electronics Engineering, Sri Venkateswara College of Engineering and Technology (Autonomous), Andhra Pradesh, India.
** Associate Professor, Department of Electrical and Electronics Engineering, Sri Venkateswara College of Engineering and Technology (Autonomous), Andhra Pradesh, India.
Purushotham, A., and Vishnuvardhan (2016). An Enhancement of power quality by using fuzzy logic controller for typical household’s applications. i-manager’s Journal on Circuits and Systems, 4(4), 19-32. https://doi.org/10.26634/jcir.4.4.12395

Abstract

This paper proposes a transformerless hybrid series active filter which is connected to a single phase distribution feeder. This system uses a sliding mode controller and filtering techniques to reduce voltage and current harmonics for a typical nonlinear load (VSC). The reactive power compensation is done by injecting sag, swell, and distortions at grid side of Point Common Coupling (PCC). In the existing methods to compensate harmonics, PI controllers were to control DC link voltage, there maybe presence of some amount of steady state error and also this PI controller may not work under continuous condition mode. So the authors have opted for Fuzzy Logic Controller (FLC) technique to improve steady state error and the system performance should be improved by reducing the harmonics. Both the existing PI based and fuzzy based controllers’ results are compared and are shown on Matlab/simulink.

Review Paper

Modern Trends in MicroGrids: A Review

G. Manohar* , D.Sreenadh reddy**
* Associate Professor, Department of Electrical and Electronics Engineering, CVR College of Engineering, Hyderabad, India.
** Assistant Professor, Department of Electrical and Electronics Engineering, CVR College of Engineering, Hyderabad, India.
Manohar, G., and Reddy, D.S. (2016). Modern Trends in MicroGrids: A Review. i-manager’s Journal on Circuits and Systems, 4(4), 33-40. https://doi.org/10.26634/jcir.4.4.12396

Abstract

Microgrids provide a powerful solution for enabling the conversion of the electric grid to a more distributed architecture and providing greater flexibility of electricity service to customers. Microgrids are small, independent electric-power grids, including both sources and loads. Microgrids have the capability to connect and disconnect effortlessly from the traditional grid. A microgrid comprises distributed generation, energy storage, loads, and a control system that is capable of operating in grid-tied mode and islanded mode. The concept of microgrid including it's architecture, components, types, mode of operation, various projects, benefits, and the challenges of microgrids have been summarized in this paper.