A Modular Approach and Simulation of an Asynchronous Machine

This article presents the modeling and simulation of the asynchronous machine. The aim of this research is the mastery of the electrical, mechanical and magnetic behaviors of this type of machine. The Matlab/Simulink is used for simulation two types of no-load and additional load services in transitional and permanent operation. The Analytical equations describing the two operating systems are evaluated and developed by a generalized model of a three-phase induction motor. The simulation results presented in this article confirms that the proposed model gave a satisfactory response in terms of torque characteristics and speed

High throughput FPGA Implementation of Data Encryption Standard with time variable sub-keys

The Data Encryption Standard (DES) was the first modern and the most popular symmetric key algorithm used for encryption and decryption of digital data. Even though it is nowadays not considered secure against a determined attacker, it is still used in legacy applications. This paper presents a secure and high-throughput Field Programming Gate Arrays (FPGA) implementation of the Data Encryption Standard algorithm. This is achieved by combining 16 pipelining concept with time variable sub-keys and compared with previous illustrated encryption algorithms. The sub-keys vary over time by changing the key schedule permutation choice 1. Therefore, every time the plaintexts are encrypted by different sub-keys. The proposed algorithm is implemented on Xilinx Spartan-3e (XC3s500e) FPGA. Our DES design achieved a data encryption rate of 10305.95 Mbit/s and 2625 number of occupied CLB slices. These results showed that the proposed implementation is one of the fastest hardware implementations with much greater security

High throughput FPGA Implementation of Advanced Encryption Standard Algorithm

 The growth of computer systems and electronic communications and transactions has meant that the need for effective security and reliability of data communication, processing and storage is more important than ever. In this context, cryptography is a high priority research area in engineering. The Advanced Encryption Standard (AES) is a symmetric-key criptographic algorithm for protecting sensitive information and is one of the most widely secure and used algorithm today. High-throughput, low power and compactness have always been topic of interest for implementing this type of algorithm. In this paper, we are interested on the development of high throughput architecture and implementation of AES algorithm, using the least amount of hardware possible. We have adopted a pipeline approach in order to reduce the critical path and achieve competitive performances in terms of throughput and efficiency. This approach is effectively tested on the AES S-Box substitution. The latter is a complex transformation and the key point to improve architecture performances. Considering the high delay and hardware required for this transformation, we proposed 7-stage pipelined S-box by using composite field in order to deal with the critical path and the occupied area resources. In addition, efficient AES key expansion architecture suitable for our proposed pipelined AES is presented. The implementation had been successfully done on Virtex-5 XC5VLX85 and Virtex-6 XC6VLX75T Field Programmable Gate Array (FPGA) devices using Xilinx ISE v14.7. Our AES design achieved a data encryption rate of 108.69 Gbps and used only 6361 slices ressource. Compared to the best previous work, this implementation improves data throughput by 5.6% and reduces the used slices to 77.69%

High –Performance using Neural Networks in Direct Torque Control for Asynchronous Machine

This article investigates solution for the biggest problem of the Direct Torque Control on the asynchronous machine to have the high dynamic performance with very simple hysteresis control scheme. The Conventional Direct Torque Control (CDTC) suffers from some drawbacks such as high current, flux and torque ripple, as well as flux control at very low speed. In this paper, we propose an intelligent approach to improve the direct torque control of induction machine which is an artificial neural networks control. The principle, the numerical procedure and the performances of this method are presented.  Simulations results show that the proposed ANN-DTC strategy effectively reduces the torque and flux ripples at low switching frequency, compared with Fuzzy Logic DTC and The Conventional DTC

Torque estimator using MPPT method for wind turbines

In this work, we presents a control scheme of the interface of a grid connected Variable Speed Wind Energy Generation System based on Doubly Fed Induction Generator (DFIG). The vectorial strategy for oriented stator flux GADA has been developed To extract the maximum power MPPT from the wind turbine. It uses a second order sliding mode controller and Kalman observer, using the super twisting algorithm. The simulation describes the effectiveness of the control strategy adopted.For A step and random profiles of the wind speed, reveals better tracking and perfect convergence of electromagnetic torque and concellation of reactive power to the stator. This control limits the mechanical stress on the tansmission shaft, improves the quality of the currents generated on the grid and optimizes the efficiency of the conversion chain

Modeling of a Microwave Amplifier Operating around 11 GHz for Radar Applications

The low noise amplifier is one of the basic functional blocks in communication systems. The main interest of the LNA at the input of the analog processing chain is to amplify the signal without adding significant noise. In this work, we have modeled a LNA for radar reception systems operating around 11 GHz, using the technique of impedance transformations with Smith chart utility. The type of transistor used is: the transistor HEMT AFP02N2-00 of Alpha Industries®. The results show that the modeled amplifier has a gain greater than 20 dB, a noise figure less than 2 dB, input and output reflection coefficients lower than -20 dB and unconditional stability

Analytic Estimation of Two-Dimensional Electron Gas Density and Current-Voltage Characteristic in AlGaN/GaN HEMT’s

This paper is mainly dedicated to understand the phenomena governing the formation of two-dimensional electron gas (2DEG) confined in the quantum well which hold the role of the channel in the high electron density transistors (HEMT) based on AlGaN / GaN heterojunction. The theory takes into account: the crystal structure, the spontaneous and piezoelectric polarization concept, the formation mechanism of two-dimensional electron gas at the AlGaN / GaN interface, the approximate resolution of the Poisson and Schrödinger equations to determine the density of Two-dimensional electron gas after the analytical formula of the current-voltage characteristic is established. Our study is also concerned with the dependence of the two-dimensional electron gas density on the following technological parameters: Aluminum molare fraction, AlGaN layer thickness and AlGaN layer doping, In order to control the influence of these parameters on the device performance. Finally, the current-voltage characteristic which reflects the variation of the drain-source current as a function of the modulation of the gate voltage has been discussed

Improvements the direct torque control performance for an induction machine using fuzzy logic controller

This article examines a solution to the major problems of induction machine control in order to achieve superior dynamic performance. Conventional direct torque control and indirect control with flux orientation have some drawbacks, such as current harmonics, torque ripples, flux ripples, and rise time. In this article, we propose a comparative analysis between previous approaches and the one using fuzzy logic. Results from the simulation show that the direct torque control method using fuzzy logic is more effective in providing a precise and fast response without overshooting, and it eliminates torque and flux fluctuations at low switching frequencies. The demonstrated improvements in dynamic performance contribute to increased operational efficiency and reliability in industrial applications

Analysis of Substrate Integrated Waveguide (SIW) Resonator and Design of Miniaturized SIW Bandpass Filter

In this paper, the substrate integrated waveguide (SIW) resonator is designed to study the influence of dielectric materials on its operating parameters (insertion loss, fractional bandwidth and unloaded Q-factor). The results obtained show that the use of high permittivity substrate in the SIW resonator by increasing its thickness allows reducing the size of resonator by causing the increase in its unloaded Q-factor. A SIW bandpass filter is designed using low temperature co-fired ceramic (LTCC) technology and high permittivity substrate. The filter has a fractional bandwidth of 27 % centered at 14.32 GHz with insertion loss of 0.7 dB

New investigation of an E-mode metal-insulator-semiconductor AlInN/AlN/GaN HEMT with an Au-T-gate

In a high electron mobility transistor (HEMT), the density of the two-dimensional electron gas (2DEG) channel is modulated by the application of a bias to a Schottky metal gate. These devices are depletion mode (D-mode), which means that a negative bias must be applied to the gate to deplete the electron channel and turn. The most challenging aspect in the present research activity on based-GaN devices is the development of a reliable way to achieve an enhancement-mode (E-mode) HEMT. Enhancement-mode GaN HEMTs would offer a simplified circuitry by eliminating the negative power supply. In this work, the aim is to investigate the different techniques which can influence the threshold voltage and shift it to a positive value. A novel E-mode metal-insulator-semiconductor (MIS) AlInN/GaN HEMT with an Au-T-gate has been investigated. The impacts of window-recess and deep-recess have been discussed, it was found that for dp=28 nm and wn=1.8 μm the threshold voltage achieves 0.7 V and the transconductance (Gm) peak value of 523 mS at Vgs=3.5 V. The drain current characteristic has been demonstrated