Design, Simulation and Analysis of a Superheterodyne Receiver Using EDA

--Seema Dahiya, Rekha Yadav and D S Malik

A single-stage down conversion superheterodyne receiver was designed, simulated and analyzed using Electronic Design Automation (EDA) software. Depending on the Dynamic Range (DR) requirements and Noise Figure (NF) requirements, the gains of the LNA were adjusted so as to enable the receiver to have maximum DR and minimum noise figure. The receiver was then modeled on the EDA simulator using the in-built components available. All the parameters were set as per the requirements and then the model was simulated. The data obtained from the simulation was analyzed by using the data display screen where any kind of plot (rectangular, polar, smith chart or tabular list, etc.) can be plotted for the data available.

© 2012 IUP. All Rights Reserved.

Comparison of Various Parameters of Square Notch Patch Antenna with DGS to Various Substrates

--A Sahaya Anselin Nisha and T Jayanthy

The paper focuses on various parameters of square notch patch antenna with Defected Ground Structure (DGS) having Rogers and FR4 substrate. DGS is an etched periodic or nonperiodic cascaded configuration defect in the ground of a planar transmission line which disturbs the shield current distribution in the ground plane, because of the defect in the ground. The theoretical performances are carried out using HFSS software. The proposed antenna is circularly polarized, and it is simulated using two various substrate materials, Rogers and FR4. When Rogers is chosen, the substrate may not be smooth, FR4 provides smooth substrate and is easily available. The antenna with Rogers substrate is having better efficiency than FR4 substrate.

© 2012 IUP. All Rights Reserved.

Suitability of Learning Algorithm for Neural Network-Based Online Flux Estimator in Sensorless Vector-Controlled Induction Motor Drives

-- A Venkadesan, S Himavathi and A Muthuramalingam

The paper identifies suitable learning algorithm for online flux estimation for sensorless vector controlled Induction Motor (IM) drives. The sensorless vector controlled IM drive requires accurate estimation of flux and speed. The speed estimation depends on the motor flux, which has to be measured or estimated. The flux measurement is difficult and expensive and hence generally estimated. Conventional voltage model equations for flux estimation are computationally rigorous and encounter major drawbacks at low frequencies/speed. Neural Network (NN)-based estimator provides an alternate solution for online flux estimation. The online flux estimator requires the NN model to be accurate, simple and structurally compact to ensure faster execution time in real implementation for effective control. This in turn, to a large extent, depends on the type of neural learning algorithms used to train the neural architecture. The Single Neuron Cascaded Neural architecture is trained offline using three types of learning algorithms to efficiently model the online flux estimator. Their performance is compared in terms of accuracy, epochs needed for training and structural compactness. The suitable learning algorithm for offline training of online NN-based flux estimation in sensorlessvector controlled IM drives is identified and the promising results obtained are presented.

© 2012 IUP. All Rights Reserved.

DC Magnetic Field Suppression Model for Multipactor Microwave Breakdown in Rectangular Waveguide Geometries

-- Akoma Henry E C A, Adediran Y A, Onu O Spencer, Agboola A O,
Ogundele D A, Iliya S Z and Aiyeola S Y

Recent communication satellites are designed to cater to a constantly increasing number of users, thus demanding increasingly higher bit rates. This combination implies increasing power levels of RF equipment downstream from the power amplifiers to the OMUXs. In this situation, different discharge phenomena such as multipactor may occur inside the microwave devices, limiting the transmit power of the satellite. Multipactor suppression techniques such as surface treatment tend to degrade with time, and surface geometry modification can be a very complex operation. Due to these limitations, this work investigated, via a mathematical model, the possibility of using a DC magnetic field to effect suppression of multipaction with particular emphasis on waveguides with rectangular geometry. The result of the analysis and simulations of the model using MATLAB and MS Excel Spreadsheet applications suggested that a small magnitude DC magnetic field perpendicular to the electric field and in the wave propagation direction is effective in reducing multipaction.

© 2012 IUP. All Rights Reserved.

Tuning of PI Controller for Brushless DC Drive Using PSO Optimization Technique

-- B Mahesh Kumar and S Sathya

The paper presents a tuning methodology for the parameters of adaptive current and speed controllers in a permanent magnet Brushless DC (BLDC) motor drive system. The parameters of both inner-loop and outer-loop PI controllers, which vary with the operating conditions of the system, are adapted in order to maintain deadbeat response for current and speed. Evenly distributed operating points are selected within the preset regions of system loading. A Particle Swarm Optimization (PSO) algorithm is employed in order to obtain the controller parameters assuring deadbeat response at each selected load.

© 2012 IUP. All Rights Reserved.

Hybrid Technique for Thermal Unit Commitment

--S Ganesan and S Subramanian

This paper presents a hybrid approach consisting of Modified Priority List and Sequential Approach (MPLSA) for solving thermal Unit Commitment (UC) problems. The solution methodology comprises two-stage processes of unit selection and economic dispatch of the committed units. The Modified Priority List (MPL) was used for unit selection, which was developed by sorting the units in descending order in respect of their Contribution Factor (CF). The CF is a ratio of the maximum generation capacity to the total installed capacity of system. Sequential Approach with Matrix Framework (SAMF) was applied to obtain the optimal dispatches of the committed units. The proposed methodology was validated by solving the standard ten-unit system, and the effectiveness of Prohibited Operating Zones (POZ) in UC problem was also studied. The initial state and minimum up and down time of units and spinning reserve requirement constraints were also considered. Numerical simulation results indicate an improvement in the solution quality. The solution methodologies are entirely based on generation limits that narrow the solution space which directs to the optimal unit selection and economic scheduling. The proposed method can be extended to solve security-constrained UC problems.

© 2012 IUP. All Rights Reserved.