Changes In Circuit Parameters Research Articles

Influence of Electrical Circuit Parameter Changes on the Local Stability of a Three-Phase Cage Induction Motor Fed with Variable Frequency

The paper presents the mathematical support and the results of some simulations related to a new method of analyzing the stability of induction motors powered at variable frequency. After a brief introduction to the proposed issue, the mathematical model of the motor, written with relative values, is detailed. Taking this model as a starting point, a Matlab stability analysis program was created. By running this program, a series of graphs were obtained, detailed in the paper (two graphs are represented each, obtained for different conditions, which facilitate their comparison and obtaining conclusions). They refer to four specific cases regarding the modification of static inductance, rotor inductance, stator resistance and rotor resistance. Analyzing these graphs, the necessary conclusions were drawn. The conclusions are important, mainly in the design phase of the machine, to finalize the structure corresponding to the most stable operation of the drive system with asynchronous motor and static voltage and frequency converter. They highlight the influences of the most important parameters of the motor on the stability of the functioning of systems with such a structure. The paper ends with a representative bibliography for the proposed study.

Comparison of Different Optimization Techniques for Model-Based Design of a Buck Zero Voltage Switching Quasi-Resonant Direct Current to Direct Current Converter

The present paper provides a comparison of different optimization techniques applied to the model-based design of a Buck Zero Voltage Switching (ZVS) Quasi-Resonant DC-DC Converter. The comparison was made both on the basis of the duration of the optimization procedures and in terms of guaranteeing the performance of the power electronic device. The main task of the paper is to present various techniques based on the use of mathematical software for the optimal design of Quasi-Resonant DC-DC converters. These topologies were chosen because in them, the design is carried out according to computational procedures, in which several iterations are often necessary for the successful completion of the process. An optimization procedure with a target function reference curve of the output voltage was used. In this way, the optimization is performed without the need for a complete design of the device but only by using base ratios, design constraints, and past experience to determine initial values and intervals of change in circuit parameters. This is also the main advantage of the used optimization of the reference curve type of the output, compared to applying other objective functions, such as achieving minimum losses or maximum efficiency of the device.

Condition Monitoring and Feature Extraction of Stator Current Phasors for Enhanced Fault Diagnosis in AC Drive

AC drives are employed mainly in process plants for various applications. In most industrial applications, Induction motor drives are preferred as they are robust, reliable, and efficient. Process industries have seen a paradigm shift from manual control to automatic control. Advancements in power electronics technology have led to smooth control of the induction motor using variable frequency drives over an entire speed range. Variable Frequency Drives (VFD) comprises of Voltage source inverter and a three phase squirrel cage induction motor. Various electric faults that are incipient in the VFD cause an abrupt change in circuit parameters resulting in insulation damage, reduced efficiency, and leading to catastrophic failure of the entire system. Hence, continuous monitoring of the system parameters such as stator current, speed, and the vibration of the machine is essential to diagnose incipient faults in the system. AI techniques have been effectively used in the fault diagnosis of electrical systems. In the proposed work, simulation results of machine learning-based fault diagnosis techniques are presented. Real-time IoT-based condition monitoring of the Variable Frequency Drive is also implemented for enhanced fault diagnosis of various incipient electrical faults in AC drives. The experimental results obtained are validated with the simulation data.

Modeling and Analysis of PV System with Fuzzy Logic MPPT Technique for a DC Microgrid under Variable Atmospheric Conditions

Due to the easiness of setup and great energy efficiency, direct current (DC) microgrids (MGs) have become more common. Solar photovoltaic (PV) and fuel cell (FC) systems drive the DC MG. Under varying irradiance and temperature, this work proposes a fuzzy logic controller (FLC) based maximum power point tracking (MPPT) approach deployed to PV panel and FC generated boost converter. PV panels must be operated at their maximum power point (MPP) to enhance efficiency and shorten the system’s payback period. There are different kinds of MPPT approaches for using PV panels at that moment. Still, the FLC-based MPPT approach was chosen in this study because it responds instantaneously to environmental changes and is unaffected by circuit parameter changes. Similarly, this research proposes a better design strategy for FLC systems. It will improve the system reliability and stability of the response of the system. An FLC evaluates PV and FC via DC–DC boost converters to obtain this enhanced response time and accuracy.

Fuzzy Logic MPPT Techniques in Solar Photovoltaic System

Abstract: This paper presents the comparative analysis of most commonly used Maximum Power Point Tracking (MPPT) techniques viz Open Circuit Voltage (OCV), Perturb and Observe (PnO) and Incremental Conductance (INC) methods that are capable of extracting maximum power from the PV generation system. The OCV technique is an indirect MPPT method that tracks the Maximum Power Point (MPP) using empirical data or mathematical expressions with numerical corrections and approximations. To operate PV panels at that point (MPP) there are many MPPT method in literature, FLC MPPT method was preferred in this study because, its rapid response to changing environmental conditions and not affecting by change of circuit parameters. The accuracy of FLC MPPT method used in this system to find MPP changes, from 94.8% to 99.4%. To charge a battery there are two traditional methods which are constant current (CC), and constant voltage (CV) methods. For fast charging with low loss constant current and voltage source is a need. One of the methods providing constant is PI control which used in this study. Keywords: FLC (Fuzzy Logic Controller), CV, CC, Simulink, MPPT

DESIGN OF MAXIMUM POWER POINT TRACKER CONTROLLER FOR BOOST CONVERTER PHOTOVOLTAIC ARRAY SYSTEM BASED ON FUZZY MAMDANI LOGIC

This paper discusses the analysis for a proposed design of a maximum power point tracker (MPPT) controller for a photovoltaic (PV) array solar system. Deploying a fuzzy Mamdani logic to track the maximum- power for the PV system when the atmospheric conditions are changed. The fuzzy Mamdani logic controller techniques have high efficiency, rapid response to new environmental factors, and are unaffected by circuit parameter changes. This controller able to adjust the duty cycle fed switching circuit of DC/DC boost to increase the output voltage of the system. By using a Simulink MATLAB, the system with the controller is stimulated and studied for different atmospheric conditions. We choose three irradiation levels of 1000, 800, and 600 W/m2 at a certain temperature of 25 ℃ and three values for the temperature of 20, 30,35 ℃ at irradiation level of 1000 W/m2 to calculate the efficiency of the algorithm. The extracted efficiency results are compared with the usual Perturb and Observe algorithm MPPT topology (P&O) for the same system design and atmospheric conditions. It was found to be the controller efficiency of the proposed algorithm is improved up to 99%. This improvement maximizes performance and reduces costs, provides adequate current and voltage, and minimizes booster losses, and improves booster reliability.

Design of PID Controller Based on ELM and Its Implementation for Buck Converters

Buck converter is a kind of converter device with high efficiency, wide adjustable output voltage, small loss, small size and light weight. Its circuit has nonlinearity and will exhibit abundant nonlinear phenomena with the change of circuit parameters, resulting in unstable output voltage and being susceptible to load and external disturbances. Therefore, a control method based on Extreme Learning Machine (ELM) combined with a proportionalintegral-derivative (PID) controller is proposed in this paper and used for output voltage control of buck converter. Firstly, the mathematical model of buck converter in Continuous Conduction Mode (CCM) is established by the state space averaging method. Then the PID tuning algorithm is designed in combination with ELM, and the stability analysis of the model is carried out. Finally, the simulation experiment is carried out under different disturbances. By comparing with the open-loop control strategy, the effectiveness of the proposed ELM-PID control strategy is verified, indicating that the proposed method can achieve the stability of output voltage and good dynamic response.

Detection of islanding and non-islanding fault disturbances in microgrid using LMD and deep stacked RVFLN based auto-encoder

This paper presents a hybrid AC/DC microgrid consisting of multiple distributed energy sources, modeled in MATLAB/Simulink environment that undergoes islanding and non-islanding (symmetrical and unsymmetrical Faults) disturbances. These disturbances result in various changes in circuit parameters (voltage, current, and frequency) and this paper focuses only on disturbed current signals that are extracted from the solar and wind-connected buses. Further to extract rich and useful fault features from the extracted current signals, an adaptive detection technique, local mean decomposition (LMD) is proposed that results in series of product functions (PFs). Various feature extraction indices are used to extract the underlying features of the decomposed PFs that are processed through a deep-stacked random vector functional link network (RVFLN) based auto-encoder (AE) technique for classifying the faults. The effectiveness of the proposed RVFLN based AE technique is evidenced in terms of classification accuracy (CA) and confusion matrix (CM). The performance of the proposed technique has been evaluated through reliability analysis (MAPE, MAE, RMSE, and CM) by comparison with various artificial neural networks under both islanding and non-islanding mode of operation.

Detection of Unusual Thermal Activities in a Semiconductor Chip Using Backside Infrared Thermal Imaging

Abstract Rapid detection of hardware Trojans on a semiconductor chip that may run malicious processes on the chip is a critical and ongoing security need. Several approaches have been investigated in the past for hardware Trojan detection, mostly based on changes in circuit parameters due to Trojan activity. Chip temperature is one such parameter that is closely related to the degree of Trojan activity. This paper carries out backside infrared (IR) imaging of a two-die three-dimensional integrated circuit (3D IC) thermal test chip in order to detect unusual thermal activities on the chip. Four distinct image processing algorithms are evaluated and compared in terms of speed, accuracy, and occurrence of false positives and negatives. The impact of background thermal activity and finite duration of Trojan activity on the accuracy of detection is investigated. Within the parameter space tested in this work, the histogram method is found to be the most effective at Trojan detection in the 3D IC. Modifications in data analysis techniques are proposed that improve Trojan detection performance. This work may help develop thermal imaging as a means for real-time Trojan detection and enhancement of security of modern semiconductor chips, including 3D ICs.

A Multigap Multiaperture Pseudospark Switch and Its Performance Analysis for High-Voltage Applications

In this article, the development and switching characterization of a coaxial three-gap demountable multigap multiaperture pseudospark switch (MGMA-PSS) prototype is presented. The investigated MGMA-PSS geometry has three gaps which are separated by two cavity drift space regions. A high dielectric constant ferroelectricbased single plasma trigger unit, located within the hollow cathode of the first gap, is used for effective discharge initiation and subsequent synchronous breakdown of the three gaps of the MGMA-PSS. To guarantee long lifetime with high currents and high hold-off voltages and optimized plasma coupling, kidney-shaped ring slot electrodes with baffles are used. Each of the gaps is designed for a minimum voltage hold-off up to 30 kV, with a total voltage hold-off for the MGMA-PSS of approximately 70 kV. Studies of switching behavior are carried out at different operating conditions, such as operating voltages (5-40 kV), hydrogen gas pressures (10-40 Pa), various trigger configurations,and change of circuit parameters [charging capacitance (36, 200, and 380 nF), load resistance(2.7 and 8.3 Ω)]. The short time-scale analysis of the breakdown voltage waveform shows steps in the voltage fall at low gas pressure (<; 20 Pa) and low hold-off voltages (<; 15 kV), which indicates a too-long time delay in plasma formation and coupling within the drift regions. This effect could not be observed at higher voltages (≥15 kV) and gas pressure (≥20 Pa). The overall performance of the threegap prototype PSS has been analyzed in terms of hold-off voltage, fall time, current rise time, peak current, delay time, and related parameters.

Coexisting Multi-Dynamics of a Physical SBT Memristor-Based Chaotic Circuit

This paper presents a new physical [Formula: see text] (SBT) memristor-based chaotic circuit. The equilibrium point and the stability of the chaotic circuit are analyzed theoretically. This circuit system exhibits multiple dynamics such as stable point, periodic cycle and chaos by means of Lyapunov exponents spectra, bifurcation diagrams, Poincaré maps and phase portraits, when the initial state or the circuit parameter changes. Specially, the circuit system exhibits coexisting multi-dynamics. This study provides insightful guidance for the design and analysis of physical memristor-based circuits.

Bio-impedance and circuit parameters: An analysis for tracking fruit ripening

The evaluation of fruit quality from the field to the table, through its storage, handling and transport has become of paramount importance to meet production and consumers demands. For this purpose, fast, reliable and low-cost non-destructive techniques are highly desirable, to avoid food waste and allow a real-time decision making. Among non-destructive techniques, Electrical Impedance Spectroscopy (EIS) has shown great potential due to the possibility to correlate the physio-chemical evolution of the fruit to changes of electrical parameters. In this paper, the effect of ageing on apples and bananas during 13 d at room temperature was studied using a microcontroller-based EIS system, in a frequency range from 100 Hz to 85 kHz.The bio-impedance changes were evaluated over time and the influence of the applied frequencies on its variation was investigated. Data were fitted with a proposed equivalent circuit, modelling both the interaction between the fruit and the sensor and the flow of current in the samples tissues. To validate the results, the circuit parameter changes were physiologically explained and the fitting compared with models found in literature. The results highlighted the potential of this non-destructive technique for monitoring the ripening and senescence of fruit, obtaining a good correlation of the impedance evolution with the low frequency points. The model fitting resulted in a Root Mean Squared Error (RMSE), for apples (376.5 Ω - 2.66%) and bananas (110.8 Ω - 2.82%), was comparable or better than best literature models. Finally, changes of circuit component values over time was explained for the electrode-fruit interaction and for the current flow in the plant tissues, giving a better insight of fruit ripening and senescence.

Stabilization and circuit implementation of a novel chemical oscillating chaotic system

Purpose This paper is aimed at investigating a novel chemical oscillating chaotic system with different attractors at fixed parameters. The typical dynamical behavior of the new chemical oscillating system is discussed, and it is found that the state selection is dependent on initial values. Then, the stabilization problem of the chemical oscillating attractors is investigated analytically and numerically. Subsequently, the novel electronic circuit of the proposed chemical oscillating chaotic system are constructed, and the influences of the changes of circuit parameters on chemical oscillating chaotic attractors are investigated. Design/methodology/approach The different attractors of the novel chemical oscillating chaotic system are investigated by changing the initial values under fixed parameters. Moreover, the active control and adaptive control methods are presented to make the chemical oscillating chaotic systems asymptotically stable at the origin based on the Lyapunov stability theory. The influences on chemical oscillating chaotic attractors are also verified by changing the circuit parameters. Findings It is found that the active control method is easier to be realized by using physical components because of its less control signal and lower cost. It is also confirmed that the adaptive control method enjoys strong anti-interference ability because of its large number of selected controllers. What can be seen from the simulation results is that the chaotic circuits are extremely dependent on circuit parameters selection. Comparisons between MATLAB simulations and Multisim simulation results show that they are consistent with each other and demonstrate that changing attractors of the chemical oscillating chaotic system exist. It is conformed that circuit parameters selection can be effective to control and realize chaotic circuits. Originality/value The different attractors of the novel chemical oscillating chaotic system are investigated by changing the initial values under fixed parameters. The characteristic of the chemical oscillating attractor is that the basin of attraction of the three-dimensional attractor is located in the first quadrant of the eight quadrants of the three-dimensional space, and the ranges of the three variables are positive. This is because the concentrations of the three chemical substances are all positive.

Modeling of DC–DC Converter Using Exact Feedback Linearization Method: A Discussion

ABSTRACTDC–DC converter finds widespread use in variety of applications. DC–DC converter inherently possess nonlinear dynamics, therefore different linearization schemes are used to get a linearized model of the converter. The classical state-space averaging method is one of the most widely used linearizing method for DC–DC converter. But the said linearization method has some inherent limitation which limits the accuracy of the developed linearized model. This paper provides a discussion of mathematical modeling of DC–DC converter operating in continuous conduction mode as well as in discontinuous conduction mode using exact feedback linearization (EFL) technique which is based on Lie algebra. A linearized model of the converter is obtained using EFL and the effect of change in duty cycle and change in circuit parameters on the frequency response has been studied. The frequency response of the EFL model and nonlinear model is matching within the range of duty cycle and load resistance considered in this paper.

Impedance Measurement and Selection of Electrochemical Equivalent Circuit of a Working PEM Fuel Cell Cathode

The dynamic impedance analysis of direct methanol fuel cell (DMFC) cathode supplied with pure oxygen is presented. Presented results were obtained during dynamic changes of the current density in working fuel cell. Investigation of the occurring processes at cathode was carried with dynamic electrochemical impedance spectroscopy (DEIS). A discussion was conducted based on the determined correlation parameter χ2. It was shown that the selection of an appropriate equivalent circuit cannot be carried out only with correlation parameter of analysis between experimental impedance spectra and the equivalent circuit. Comprehensive analysis of equivalent circuit parameter changes during fuel cell working is needed to determine appropriate equivalent model. Thanks to DEIS technique, comparing of the different equivalent circuits proposed in other works during dynamic changes of operating condition could be presented. In addition, the new electrical circuit has been proposed to describe the cathode performance with poisoned electrocatalyst in fuel cell with reduced efficiency.Graphical The equivalent electrical circuit of an operating fuel cell cathode

Transformer Winding Deformation Profile using Modified Electrical Equivalent Circuit

This study presents a generalized methodology to predict the transformer winding deformation profile through Sweep Frequency Response Analysis using Finite Element Method based Magneto Structural Analysis and proposed modified equivalent circuit. Monitoring and diagnosis of fault in any power apparatus is necessary to increase the quality life of the apparatus. In general all the power transformers are designed to withstand the mechanical forces due to short circuit faults. However, mechanical forces may exceed the specified limits during severe incidents leading to winding deformation. Winding deformation is one of the causes for the power transformer outages. In the present work, deformation profile of the winding for different short circuit currents are computed using Finite Element Method based Magneto-structural analysis. The change in circuit parameters of the deformed windings are computed using Finite Element Method based field analyses and the corresponding Sweep Frequency Responses are obtained using the modified electrical equivalent circuit. From the change in resonance frequencies, the displacement profile of the winding can be predicted which will be useful for design engineers to check the withstand capability of transformer.

Thermodynamics of squeezed states in mesoscopic circuits

Based on the information theory, we present a density matrix to discuss coherent and squeezed states in a mesoscopic LC circuit with time-dependent frequency. With the relevant operators included in the density matrix, a connection between the appearance of coherent and squeezed states is established, i.e., the quantum state evolution of the system is closely related to the initial state. Generally speaking, due to the effect of environment temperature, the mesoscopic LC circuit will evolve to a squeezed state when it initially lies in an excited state. In particular, at a low temperature, step changes of circuit parameters will result in a squeezed minimum uncertainty state if the resonance frequency remains the same after the change.

Theoretical analysis of the noncardiac limits to maximum exercise.

When right atrial pressure (Pra) is greater than zero (atmospheric pressure), cardiac output is determined by the intersection of two functions, cardiac function and return function, which is used here to mean the determinants of venous return. When Pra < or = 0, flow is only determined by circuit function. The objective of this analysis was to determine the potential changes in return function that need to occur to allow the maximum cardiac output during exercise when Pra < or = 0 or is constant. The analysis expands on the model of Green and Jackman and includes the effects of changes in circuit parameters, including venous resistance, changes in capacitance, and muscle contractions. The analysis is based on the model of the circulation proposed by Permutt and co-workers, which assumes that the systemic circulation has two lumped compliant regions in parallel with independent inflow and outflow resistances. Changes in total flow in this model can come about by changes in the distribution of flow between the regions, recruitment of unstressed vascular volume, and changes in the regional venous resistances. The data for the analysis are from previous animal studies and are normalized to a 70-kg man. The major conclusions are that, to achieve the high cardiac output that occurs at peak exercise, there need to be marked changes in the distribution of blood flow, recruitment of unstressed volume, and the venous resistance draining vascular beds. A consequence of the increase in peripheral flow is a marked increase in pressure in the veins of the working muscle. Muscle contractions are potentially a very important mechanism for transiently decreasing this pressure and preventing excessive filtration of plasma during exercise.

A comparative study of constant-voltage and constant-temperature hot-wire anemometers:

The dynamic response of the constant-voltage anemometer (CVA) system was investigated both analytically and experimentally and compared to that of the CTA. The frequency response functions of the CVA system for a number of different circuit parameters and flow conditions were determined via laser-based radiative heating of the hot-wire sensor. A 2nd-order linear systems model of the CVA was developed to provide insight to the dynamic response and to interpret the experimental results. The qualitative variations in the frequency response function with changes in circuit parameters are in agreement with the model. The experimentally determined frequency-response functions of the CVA systems used in this study were found to have little dependence on the wire overheat ratio and Reynolds number.

Coexistence of excitability, Hopf and Turing modes in a one-dimensional array of nonlinear circuits

The behavior in the vicinity of a point where excitable, Hopf and Turing modes coexisting is analyzed within the framework of a simplified version of Chua's nonlinear circuits. The different factors (e.g., initial and boundary conditions and small changes in circuit parameters) which determine the final state of the system are numerically studied. >