Electrical and Capacitance Diagnostic Techniques as a Support for the Development of Silicon Heterojunction Solar Cells

In this paper we present the utilization of capacitance and current-voltage diagnostic techniques to analyse silicon heterojunction solar cell structures properties, particularly focused on the inspection of the amorphous emitter and amorphous silicon/crystalline silicon hetero-interface. The capacitance characterization of investigated samples have revealed the need for improvement of the a-Si:H/c-Si heterointerface quality as a main direction to obtain superior output performance of heterojunction cells. In addition, current-voltage characterization emphasized importance for enhancement of the light management in the structure. The obtained results demonstrate that electrical and capacitance diagnostic techniques can represents important diagnostic tools in the process of optimization of solar cells.

Locating Pd in Transformers through Detailed Model and Neural Networks

In a power transformer as one of the major component in electric power networks, partial discharge (PD) is a major source of insulation failure. Therefore the accurate and high speed techniques for locating of PD sources are required regarding to repair and maintenance. In this paper an attempt has been made to introduce the novel methods based on two different artificial neural networks (ANN) for identifying PD location in the power transformers. In present report Fuzzy ARTmap and Bayesian neural networks are employed for PD locating while using detailed model (DM) for a power transformer for simulation purposes. In present paper PD phenomenon is implemented in different points of transformer winding using threecapacitor model. Then impulse test is applied to transformer terminals in order to use produced current in neutral point for training and test of employed ANNs. In practice obtained current signals include noise components. Thus the performance of Fuzzy ARTmap and Bayesian networks for correct identification of PD location in a noisy condition for detected currents is also investigated. In this paper RBF learning procedure is used for Bayesian network, while Markov chain Monte Carlo (MCMC) method is employed for training of Fuzzy ARTmap network for locating PD in a power transformer winding and results are compared.

Analysis of Power Converter Losses in Vector Control System of a Self–Excited Induction Generator

This paper provides analysis of losses in the hysteresis-driven three-phase power converter with IGBTs and free-wheeling diodes. The converter under consideration is part of the self-excited induction generator (SEIG) vector control system. For the analysis, the SEIG vector control system is used in which the induction generator iron losses are taken into account. The power converter losses are determined by using a suitable loss estimation algorithm reported in literature. The chosen algorithm allows the power converter losses to be determined both by type (switching/conduction losses) and by converter component (IGBT/diode losses). The overall power converter losses are determined over wide ranges of rotor speed, dc-link voltage and load resistance, and subsequently used for offline correction of the overall control system’s losses (efficiency) obtained through control system simulations with an ideal power converter. The control system’s efficiency values obtained after the correction are compared with the measured values.

Image Encryption based on Chaotic Map and Reversible Integer Wavelet Transform

In recent years, there has been growing interesting in image encryption based on chaotic maps and wavelet transform. In this paper, a novel scheme for image encryption based on chaotic maps and reversible integer wavelet transform is proposed. Firstly, the cipher key which is related to plain-image is used to generate different parameters and initial values of chaotic maps. Then the plain-image is permuted by the order from chaotic maps, and processed by integer wavelet transform. A part of transform coefficient is diffused by the orbits of chaotic maps. Finally, the cipher image is obtained by inverse integer wavelet transform based on the diffused coefficient. Numerical experimental results and comparing with previous works show that the proposed scheme possesses higher security than previous works, which is suitable for protecting the image information.

High Performances of Five–Phase Induction Machine Feeding by A [3 × 5] Matrix Converter

In this paper, we study an analytic technique to control matrix converter for a four-quadrant five-phase induction machine drive with use PWM five intervals modulation strategy. The multiphase induction machine is feeding by a matrix converter using a three-phase network. Special emphasis is given to the sinusoidal five phase voltage in the output and five phase voltage input current modulation. Simulation results are presented.

Advanced Control Strategy for Single–Phase Voltage–Source Active Rectifier with Low Harmonic Emission

This paper introduces the advanced control of single-phase voltage-source active rectifier. This control provide direct control of trolley-wire current and active damping of low-frequency disturbances at the converter ac side. Our proposed control strategy combines PR controller with feed-forward model and low-frequency harmonic compensator based on resonant controllers. Achieved experimental results show excellent converter behavior, where converter is fed by strongly distorted supply voltage.

Hybrid Chaos Synchronization of Four–Scroll Systems via Active Control

This paper investigates the hybrid chaos synchronization of identical Wang four-scroll systems (Wang, 2009), identical Liu-Chen four-scroll systems (Liu and Chen, 2004) and non-identical Wang and Liu-Chen four-scroll systems. Active control method is the method adopted to achieve the hybrid chaos synchronization of the four-scroll chaotic systems addressed in this paper and our synchronization results are established using Lyapunov stability theory. Since the Lyapunov exponents are not required for these calculations, the active control method is effective and convenient to hybrid synchronize identical and different Wang and Liu-Chen four-scroll chaotic systems. Numerical simulations are also shown to illustrate and validate the hybrid synchronization results derived in this paper.

Gain–Scheduled Controller Design: Variable Weighting Approach

Among the most popular approaches to non-linear control is gain-scheduled (GS) controller, which can have better performance than robust and other ones. Our approach is based on a consideration that in linear parameter varying (LPV) system, scheduling parameters and their derivatives with respect to time are supposed to lie in a priori given hyper rectangles. To access the performance quality a new quadratic cost function is used, where weighting matrices are time varying depends on scheduled parameter. The class of control structure includes decentralised fixed order output feedbacks like PID controller. Numerical examples illustrate the effectiveness of the proposed approach.

Modeling and Identification of Nonlinear Cascade and Sandwich Systems with General Backlash

The paper deals with modeling and identification of nonlinear cascade and sandwich systems including general backlash, where instead of the straight lines determining the upward and downward parts of backlash characteristic, general curves are considered. This enables more precise modeling of mechanical parts and improves the performance of control systems. The analytical description of the general backlash leads to mathematical models of the cascade system with output general backlash and the sandwich system with internal general backlash, where all the model parameters are separated. Hence, the identification is solved as a quasi-linear problem. Iterative algorithms with internal variables estimation are proposed and illustrative examples are included.

Inductive High Power Transfer Technologies for Electric Vehicles

Problems associated with ”how to charge the battery pack of the electric vehicle” become more important every passing day. Most logical solution currently is the non-contact method of charge, possessing a number of advantages over standard contact methods for charging. This article focuses on methods for Inductive high power contact-less transfer of energy at relatively small distances, their advantages and disadvantages. Described is a developed Inductive Power Transfer (IPT) system for fast charging of electric vehicles with nominal power of 30 kW over 7 to 9 cm air gap.