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On-line Estimation of Electrolytic Capacitor Parameters using Recursive Least Squares and Sliding Mode Differentiators
... This method estimates the capacitance according to the relationship between the decoupling capacitor and other variables in PFC converter based on a large amount of data. In [9], a sliding mode differentiator obtains the derivatives of the voltage and current of the decoupling capacitor, and the recursive least square method is used to estimate the capacitance of the decoupling capacitor. In addition, neural network [10,11,12,13], level modulation theory [14] and signal injection method [15,16] are used to achieve the relationship between the decoupling capacitor voltage and the grid current to realize high-precision estimation of decoupling capacitance. ...
Inaccurate capacitance significantly increases the DC-Link ripple voltage of active power decoupling circuit (APDC). To solve this problem, a high-precision online capacitance estimation method is proposed. This method converts the AC components of decoupling capacitor into the sum of DC component and AC component with 8 times grid frequency, which is beneficial to the extraction of DC component. This DC component replaces the AC component to effectively eliminate the periodic capacitance mutation, and accurately estimate the capacitance. Based on the capacitance, the DC-Link ripple is controlled with the set scope. Experimental results verify the effectiveness of the proposed method.
... This scheme utilizes the sliding mode differentiators and Kalman filter for the online estimation of ESR and capacitance parameters of AEC under noisy conditions. In [10] an on-line parameter measuring scheme for Aluminium Electrolytic Capacitor degradation which involves the Recursive Least Square algorithm with sliding mode differentiators and forgetting factor is proposed. It can concurrently estimate the equivalent capacitance Ceff and the AEC Equivalent Series Resistance (ESR) in noisy current and voltage measurements. ...
Objectives: To design and simulate a buck converter and detector circuit which can prognostically indicate the power supply failure. Failure of Aluminium Electrolytic Capacitor (AEC) is considered as the parameter causing the power supply failure. To analyse variation of output ripple voltage due to possible changes in the Equivalent Series Resistance (ESR) and effective capacitance of the capacitor and design a detector to detect the failure of power supply prognostically. Methods: A DC-DC buck converter in SMPS topology is designed by assuming an input voltage of 12V with 3 volts possible fluctuations and an output voltage of 3.3 volts is desired. Simulation is carried out to measure the variation in output ripple voltage caused due to aging of electrolytic capacitor using TINA by Texas Instruments. A detector is also designed to compare the ripple voltage and a predefined threshold voltage so as to indicate the possible failure of Switched Mode Power Supply (SMPS) well in advance by monitoring the output ripple increase. Novelty: Having a fault tolerant power supply is very important in safety critical applications. Here by monitoring the output ripple variation, the degradation of AEC is predicted by calculating the ESR and capacitance variation. This simple yet effective prognostic detection will support in the design of fault tolerant power supplies. Highlight: It is found that, the ripple at the output increases with aging of the electrolytic capacitor, as with time the equivalent capacitance decreases and Equivalent Series Resistance (ESR) of the capacitor increases. The designed detector output is found to prognostically indicate the failure of SMPS.
... However, they are offline methods that require isolating the capacitor from the operation mode. The online scheme estimates capacitor parameters using sliding mode differentiators and recursive algorithms, as reported in [47,48]. The capacitor voltage and current can be affected by noise; therefore, the sliding mode differentiator is used to provide satisfactory derivatives. ...
Capacitors are critical components of power converter systems as they influence the cost, size, performance, and scale of such systems. However, capacitors exhibit the highest degeneration and breakdown rates among all power converter components due to their wear-out failures and short lifespans. Therefore, condition monitoring is a vital process to estimate the health status of capacitors and to provide predictive maintenance for ensuring stability in the operation of power converter systems. The equivalent series resistance (ESR) and the capacitance of the capacitor are two widely used parameters for evaluating the health status of capacitors. Unlike the ESR, the capacitance of a capacitor is suitable for the health monitoring of various types of capacitors; therefore, it is more preferable for large-scale systems. This paper presents an overview of previous research addressing this aspect of capacitors and provides a better understanding of the capacitance monitoring of capacitors utilized in power converter systems.
Capacitors are one type of reliability-critical components in power electronic systems. In the last two decades, many efforts in academic research have been devoted to the condition monitoring of capacitors to estimate their health status. Industry applications are demanding more reliable power electronics products with preventive maintenance. Nevertheless, most of the developed capacitor condition monitoring technologies are rarely adopted by industry due to the complexity, increased cost, and other relevant issues. An overview of the prior-art research in this area is therefore needed to justify the required resources and the corresponding performance of each key method. It serves to provide a guideline for industry to evaluate the available solutions by technology benchmarking, as well as to advance the academic research by discussing the history development and the future opportunities. Therefore, this paper first classifies the capacitor condition monitoring methods into three categories, then the respective technology evolution in the last two decades is summarized. Finally, the state-of-the-art research and the future opportunities targeting for industry applications are given.
DC-link capacitors are an important part in the majority of power electronic converters which contribute to cost, size and failure rate on a considerable scale. From capacitor users' viewpoint, this paper presents a review on the improvement of reliability of dc link in power electronic converters from two aspects: 1) reliability-oriented dc-link design solutions; 2) conditioning monitoring of dc-link capacitors during operation. Failure mechanisms, failure modes and lifetime models of capacitors suitable for the applications are also discussed as a basis to understand the physics-of-failure. This review serves to provide a clear picture of the state-of-the-art research in this area and to identify the corresponding challenges and future research directions for capacitors and their dc-link applications.
The synthesis of a control algorithm that stirs a nonlinear system to a given manifold and keeps it within this constraint is considered. Usually, what is called sliding mode is employed in such synthesis. This sliding mode is characterized, in practice, by a high-frequency switching of the control. It turns out that the deviation of the system from its prescribed constraints (sliding accuracy) is proportional to the switching time delay. A new class of sliding modes and algorithms is presented and the concept of sliding mode order is introduced. These algorithms feature a bounded control continuously depending on time, with discontinuities only in the control derivative. It is also shown that the sliding accuracy is proportional to the square of the switching time delay.
In a high-rate indoor wireless personal communication system, the delay spread due to multipath propagation results in intersymbol interference (ISI) which can significantly increase the transmission bit error rate (BER). Decision feedback equalizer (DFE) is an efficient approach to combating the ISI. Recursive least squares (RLS) algorithm with a constant forgetting factor is often used to update the tap-coefficient vector of the DFE for ISI-free transmission. However, using a constant forgetting factor may not yield the optimal performance in a nonstationary environment. In this paper, an adaptive algorithm is developed to obtain a time-varying forgetting factor. The forgetting factor is used with the RLS algorithm in a DFE for calculating the tap-coefficient vector in order to minimize the squared equalization error due to input noise and due to channel dynamics. The algorithm is derived based on the argument that, for optimal filtering, the equalization errors should be uncorrelated. The adaptive forgetting factor can be obtained based on on-line equalization error measurements. Computer simulation results demonstrate that better transmission performance can be achieved by using the RLS algorithm with the adaptive forgetting factor than that with a constant forgetting factor previously proposed for optimal steady-state performance or a variable forgetting factor for a near deterministic system.
This paper presents a low cost method to realize a real time condition monitoring and a predictive maintenance system of an electrolytic capacitor used in uninterrupted power supplies (UPS). This method consists in detecting the changes on real time in equivalent series resistance (ESR) and the capacitance C values of the electrolytic capacitors. Simulation and experimental results are presented to illustrate the proposed monitoring technique. The proposed method can be used in UPS where waveforms are continuously varying in amplitude, frequency and versus temperature. The proposed on line failure prediction method has the merits of using only the existent resources in UPS and with the use of knower algorithms.
The object of this paper is to present an economic electronic
module integrated on an electrolytic capacitor that is able to indicate
the moment when it must be changed. First, with a switchmode power
supply as an example, the high probability of electrolytic capacitor
failure with respect to other power components is noted. Second, the
authors recall that the increase of the equivalent series resistance
(ESR) of the capacitor is the best indicator of their faulty state. From
the measurements of the voltage ripple and the capacitor current, one
can deduce the ESR; the latter is compared to the ESR value of the sound
capacitor deduced from the component case temperature. Thus, the
capacitor deterioration can be diagnosed
This work presents a cost-motivated method for reliability health monitoring of an electrolytic capacitor. The monitoring system uses a combination of analogue and digital electronics to optimize the cost. The capacitor aging is detected by on-line and in-situ detection of the evolution of the ESR (Equivalent Series Resistance) which is the most reliable ageing indicator. The algorithm uses waveforms naturally present in the power electronic train and thus the condition monitoring can be performed continuously and without interruption of the industrial process. The monitoring method estimates the ESR by adjusting a capacitor model that emulates the monitored capacitor. The limitation in accuracy of the estimation has no significant influence on the lifetime determination. The principle of the method is explained, along with the design tradeoffs and the monitoring procedure is described in detail. The paper also presents the experimental results obtained from a prototype during accelerated in-situ/inverter ageing tests.
Electrolytic capacitors are an important component within power electronics systems which are known to exhibit poorer reliability compared to other components within the system. In this paper, the changes in electrical parameters (capacitance and equivalent series resistance) which occur as electrolytic capacitors age are characterised at regular intervals over the life of the capacitors. Ageing is observed under three different bias conditions: no bias; constant voltage bias and square wave excitation and at two different ambient temperatures. The data captured within this work presents the changes in capacitor properties from new, reaching to a point which the capacitor parameters have changed sufficiently, such that the capacitor can be considered to have failed. Such data will prove valuable in the development of a system designed to determine the state of health of a capacitor, or could be used to predict its remaining useful lifetime.
The first article in this series [1] covered the early history of electrolytic capacitors, from their invention around 1880 to the invention of the modern Al electrolytic capacitor structure in 1925. The second article [2] takes us from Samuel Ruben's 1925 invention to the wide range of Al electrolytic capacitors presently on the market. The present article discusses electrolytic capacitors based on metals other than Al.
The sliding mode control methodology has proven effective in dealing with complex dynamical systems affected by disturbances, uncertainties and unmodeled dynamics. Robust control technology based on this methodology has been applied to many real-world problems, especially in the areas of aerospace control, electric power systems, electromechanical systems, and robotics. Sliding Mode Control and Observation represents the first textbook that starts with classical sliding mode control techniques and progresses toward newly developed higher-order sliding mode control and observation algorithms and their applications.
The present volume addresses a range of sliding mode control issues, including:
*Conventional sliding mode controller and observer design
*Second-order sliding mode controllers and differentiators
*Frequency domain analysis of conventional and second-order sliding mode controllers
*Higher-order sliding mode controllers and differentiators
*Higher-order sliding mode observers
*Sliding mode disturbance observer based control
*Numerous applications, including reusable launch vehicle and satellite formation control, blood glucose regulation, and car steering control are used as case studies
Sliding Mode Control and Observation is aimed at graduate students with a basic knowledge of classical control theory and some knowledge of state-space methods and nonlinear systems, while being of interest to a wider audience of graduate students in electrical/mechanical/aerospace engineering and applied mathematics, as well as researchers in electrical, computer, chemical, civil, mechanical, aeronautical, and industrial engineering, applied mathematicians, control engineers, and physicists. Sliding Mode Control and Observation provides the necessary tools for graduate students, researchers and engineers to robustly control complex and uncertain nonlinear dynamical systems. Exercises provided at the end of each chapter make this an ideal text for an advanced course taught in control theory.
Choosing a capacitor technology for a given task can be easy, but laying out the reasons why it is the best choice is not. In this report, the authors shares is expertise in this field. The author has spent the past thirty years designing, specifying and troubleshooting capacitors.
The practical implementation of sliding mode controllers usually assumes knowledge of all system states. It also typically requires information (at least in terms of the boundaries) about the combined effect of drift terms, i.e., the internal and external disturbances of the system. In this chapter a feedback linearization-like technique is used for obtaining the input–output dynamics and reducing all disturbances to the matched ones. Then the sliding variables are introduced and their dynamics are derived. The higher-order sliding mode differentiator-based observer, which was discussed in Chap. 7, is used to the estimate system states, the derivatives of the sliding variables, as well as the drift terms. Therefore, in finite time, all information about the sliding variable dynamics becomes available. The estimated drift term is then used in the feedback loop to compensate the disturbances. The observed states are then used to design any (continuous) robust state-space controller while eliminating the chattering effect. Two case studies, launch vehicle and satellite formation control, illustrate the discussed robust control technique.
Experts shared views on the development of aluminum electrolytic capacitors. Concepts emerged for increasing the specific capacitance of the anode after the introduction of wound foils for Al electrolytic capacitors. The use of electro-chemical etching from the mid-1930s from increased the effective surface of the aluminum anode greatly. The German manufacturer AEG-Hydra-Werke in Berlin was manufacturing electrolytic capacitors on an industrial scale from the early 1930s in addition to William Dubilier who advanced electrolytic capacitor technology based on the 1931 industrial-scale factory in Plainfield, New Jersey, US.
This first of three articles on electrolytic-capacitor technology places the technology in a broad historical context and traces the technology from the 1880s to about 1925, when a patent was submitted for the modern form of electrolytic capacitor. The second article will trace the development of modern "e-caps".
Precise dynamic models of processes are required for many applications, ranging from control engineering to the natural sciences and economics. Frequently, such precise models cannot be derived using theoretical considerations alone. Therefore, they must be determined experimentally. This book treats the determination of dynamic models based on measurements taken at the process, which is known as system identification or process identification. Both offline and online methods are presented, i.e. methods that post-process the measured data as well as methods that provide models during the measurement. The book is theory-oriented and application-oriented and most methods covered have been used successfully in practical applications for many different processes. Illustrative examples in this book with real measured data range from hydraulic and electric actuators, machine tools, industrial robots, pumps, vehicles to combustion engines. Real experimental data is also provided on the Springer webpage, allowing readers to gather their first experience with the methods presented in this book. Among others, the book covers the following subjects: determination of the nonparametric frequency response, (fast) Fourier transform, correlation analysis, parameter estimation with a focus on the method of Least Squares and modifications, identification of time-variant processes, identification in closed-loop, identification of continuous time processes, and subspace methods. Some methods for nonlinear system identification are also considered, such as the Extended Kalman filter and neural networks. The different methods are compared by using a real three-mass oscillator process, a model of a drive train. For many identification methods, hints for the practical implementation and application are provided. The book is intended to meet the needs of students and practicing engineers working in research and development, design and manufacturing. © Springer-Verlag Berlin Heidelberg 2011. All rights are reserved.
Homogeneous sliding-mode-based differentiators (HD) are known to provide for the high-accuracy robust estimation of derivatives in the presence of sampling noises and discrete measurements, provided that the differentiator dynamics evolve in continuous time. The popular one-step Euler discrete-time implementation is proved to cause differentiation accuracy deterioration, if the differentiation order exceeds 1. A novel discrete-time realization of the HD is proposed, which preserves the ultimate accuracy of the continuous-time HD also with discrete measurements.
This paper discusses experimental setups for health monitoring and prognostics of electrolytic capacitors under nominal operation and accelerated aging conditions. Electrolytic capacitors have higher failure rates than other components in electronic systems like power drives, power converters etc. Our current work focuses on developing first-principles-based degradation models for electrolytic capacitors under varying electrical and thermal stress conditions. Prognostics and health management for electronic systems aims to predict the onset of faults, study causes for system degradation, and accurately compute remaining useful life. Accelerated life test methods are often used in prognostics research as a way to model multiple causes and assess the effects of the degradation process through time. It also allows for the identification and study of different failure mechanisms and their relationships under different operating conditions. Experiments are designed for aging of the capacitors such that the degradation pattern induced by the aging can be monitored and analyzed. Experimental setups and data collection methods are presented to demonstrate this approach.
This paper describes online techniques for monitoring the health of the two most sensitive components in power electronic systems, namely electrolytic filtering capacitors and controllable semiconductor switches (i.e. MOSFETs and IGBTs). The paper begins with a brief discussion of the primary failure mechanisms for these two types of components. It then presents an online technique designed to measure capacitor ESR, which is a key indicator of capacitor health. Subsequent sections address similar online approaches for tracking the on-state resistance of MOSFETs and the collector-to-emitter saturation voltage of IGBTs. Experimental results demonstrate the effectiveness of these techniques.
The main problem in differentiator design is to combine differentiation exactness with robustness in respect to possible measurement errors and input noises. The proposed differentiator provides for proportionality of the maximal differentiation error to the square root of the maximal deviation of the measured input signal from the base signal. Such an order of the differentiation error is shown to be the best possible one when the only information known on the base signal is an upper bound for Lipschitz’s constant of the derivative.
A remaining useful life prediction methodology for elec-trolytic capacitors is presented. This methodology is based on the Kalman filter framework and an empirical degradation model. Electrolytic capacitors are used in several applications ranging from power supplies on critical avionics equipment to power drivers for electro-mechanical actuators. These devices are known for their comparatively low reliability and given their criticality in electronics subsystems they are a good can-didate for component level prognostics and health manage-ment. Prognostics provides a way to assess remaining use-ful life of a capacitor based on its current state of health and its anticipated future usage and operational conditions. We present here also, experimental results of an accelerated ag-ing test under electrical stresses. The data obtained in this test form the basis for a remaining life prediction algorithm where a model of the degradation process is suggested. This prelim-inary remaining life prediction algorithm serves as a demon-stration of how prognostics methodologies could be used for electrolytic capacitors. In addition, the use degradation pro-gression data from accelerated aging, provides an avenue for validation of applications of the Kalman filter based prognos-tics methods typically used for remaining useful life predic-tions in other applications.
Approach your problems from the right end It isn't that they can't see the solution. It is and begin with the answers. Then one day, that they can't see the problem. perhaps you will find the final question. G. K. Chesterton. The Scandal of Father 'The Hermit Clad in Crane Feathers' in R. Brown 'The point of a Pin'. van Gulik's The Chinese Maze Murders. Growing specialization and diversification have brought a host of monographs and textbooks on increasingly specialized topics. However, the "tree" of knowledge of mathematics and related fields does not grow only by putting forth new branches. It also happens, quite often in fact, that branches which were thought to be completely disparate are suddenly seen to be related. Further, the kind and level of sophistication of mathematics applied in various sciences has changed drastically in recent years: measure theory is used (non-trivially) in regional and theoretical economics; algebraic geometry interacts with physics; the Minkowsky lemma, coding theory and the structure of water meet one another in packing and covering theory; quantum fields, crystal defects and mathematical programming profit from homotopy theory; Lie algebras are relevant to filtering; and prediction and electrical engineering can use Stein spaces. And in addition to this there are such new emerging subdisciplines as "experimental mathematics", "CFD", "completely integrable systems", "chaos, synergetics and large-scale order", which are almost impossible to fit into the existing classification schemes. They draw upon widely different sections of mathematics.
Aluminum electrolytic capacitors are usually used in DC-DC converters as smoothing capacitors. According to the statistics data, they are the weakest among various power components in the DC-DC converter. With the increase of the running time, the performance degradation of electrolytic capacitors reflects in electrical parameters, mainly the Equivalent Series Resistance (ESR) and capacitance. The best indicator of the output filter capacitor failure is the increase of ESR. And the output ripple voltage of the converter increases with respect to ESR. Monitoring the ESR variation of the electrolytic capacitor, achieving by voltage and current ripple, can estimate the health state of the converter.
Understanding the ageing mechanisms of electronic components critical avionics systems such as the GPS and INAV are of critical importance. Electrolytic capac-itors and MOSFET's have higher failure rates among the components of DC-DC power converter systems. Our current work focuses on analyzing and modeling elec-trolytic capacitor degradation and its effects on the out-put of DC-DC converter systems. The output degrada-tion is typically measured by an increase in ESR (Equiv-alent Series Resistance) and decrease in the capacitance value over long periods of use even under nominal oper-ating conditions. Typically the primary effect of degra-dation is increased ripple current and this has adverse effects on downstream components. For example, in avionics systems where the power supply drives a GPS unit, ripple currents can cause glitches in the GPS posi-tion and velocity output, and this may cause errors in the Inertial Navigation (INAV) system, causing the aircraft to fly off course. In this paper, we present the details of our ageing methodology along with details of experi-ments and analysis of the results.
The classical filtering and prediction problem is re-examined using the Bode-Sliannon representation of random processes and the “state-transition” method of analysis of dynamic systems. New results are: (1) The formulation and methods of solution of the problem apply without modification to stationary and nonstationary statistics and to growing-memory and infinitememory filters. (2) A nonlinear difference (or differential) equation is derived for the covariance matrix of the optimal estimation error. From the solution of this equation the coefficients of the difference (or differential) equation of the optimal linear filter are obtained without further calculations. (3) The filtering problem is shown to be the dual of the noise-free regulator problem. The new method developed here is applied to two well-known problems, confirming and extending earlier results. The discussion is largely self-contained and proceeds from first principles; basic concepts of the theory of random processes are reviewed in the Appendix.
This paper presents an economic and automatic experimental technique that allows the determination of the equivalent circuit of aluminum electrolytic capacitors at their operating conditions. The equivalent circuit of an electrolytic capacitor comprises an equivalent series inductance (ESL), an equivalent series resistance (ESR) and a capacitance (C). Both C and ESR values change with frequency, temperature and aging. The knowledge of the capacitor ESR value is essential to achieve the best design proposal for switch mode power supplies (SMPS) and in the selection of the best capacitors used in the DC link of adjustable speed drives (ASD). On the other hand, the accurate knowledge of the capacitor capacitance is also very important in the rectifiers design and in the choice of the best capacitor for the DC link of ASD. Moreover, the knowledge of both parameters allows the evaluation of the capacitor state condition. To implement the proposed technique, two distinct circuits should be considered. The first one accounts for the estimation of the ESR and reactance of the capacitor, while the second one allows the estimation of the capacitor capacitance. To implement the first circuit, it is necessary to put the capacitor under test in series with a resistor and connect them to a sinusoidal voltage. The relationship between the gain and phase of the capacitor voltage and current waveforms, obtained from sinusoidal fitting, gives enough information to compute both ESR and reactance of the capacitor. The second circuit is a simple charge/discharge circuit. From the relationship between the capacitor current and voltage, during discharge, it is possible to compute its capacitance using the least mean square algorithm.
In this paper, a novel online technique for estimating the parameters of a DC/DC buck converter through a continuous time model is proposed. Standard least mean squares algorithm is applied among other formulations, taking into account only the non conduction state during a single switching cycle. The problem of derivative calculation of the needed voltage and current signals is solved by polynomial interpolation.
In this paper, simplified regression models useful for parameter extraction are obtained from the hybrid models of Buck and Boost DC/DC converters. These models are used in the ESR estimation of output filter capacitors present in the same circuits for diagnostic purposes. Advantages obtained through the simplified models are outlined regarding the original complete regression models obtained from the respective hybrid models. The simplified and the original parameter estimation methods are both applied and compared between them regarding accuracy, data processing time and reliability of the implemented algorithms. Results obtained from simulations and experimental results are presented.
A century of diligent R&D has resulted in a wide range of ceramic dielectrics and processing technologies. The technology used to manufacture an MLCC (multilayer ceramic capacitors) that costs pennies was unimaginable 30 years ago. The present trends of enhanced mobility, connectivity, and reliability in consumer, industrial, and military electronics will continue to drive future innovations in ceramic capacitor technology. In addition, power electronics applications are an emerging market in which ceramic capacitors will play an increasing role through improved breakdown strength, enhanced dielectric stability in harsh environments, and innovative packaging. The investment made by the US government to develop high energy density and high temperature capacitor technology will also contribute to the advancement of dielectric materials technology for pulse and power electronic capacitors.
The electrolytic capacitor usually has the shortest span of life in the power converter. This paper presents a new low cost implementation of a real time condition monitoring and a predictive maintenance system of an electrolytic capacitor used in Uninterruptible Power Supplies (UPS). It consists of detecting the changes in real time in equivalent series resistance (ESR) and the capacitance C values of the electrolytic capacitors. The proposed method can be used in UPS where waveforms are continuously varying in amplitude, frequency and versus ambient temperature. This method has the merits of using known algorithms and only the existent resources in UPS.
An account is given of recursive regression and Kalman filtering that gathers the important results and the ideas that lie behind them. It emphasises areas where econometricians have made contributions, including methods for handling the initial-value problem associated with nonstationary processes and algorithms for fixed-interval smoothing.
The sections in this article are1The Problem2Background and Literature3Outline4Displaying the Basic Ideas: Arx Models and the Linear Least Squares Method5Model Structures I: Linear Models6Model Structures Ii: Nonlinear Black-Box Models7General Parameter Estimation Techniques8Special Estimation Techniques for Linear Black-Box Models9Data Quality10Model Validation and Model Selection11Back to Data: The Practical Side of Identification
2 7212 Bellona Ave. 3 Numbers in brackets designate References at end of paper. 4 Of course, in general these tasks may be done better by nonlinear filters. At present, however, little or nothing is known about how to obtain (both theoretically and practically) these nonlinear filters. Contributed by the Instruments and Regulators Division and presented at the Instruments and Regulators Conference, March 29-Apri1 2, 1959, of THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS. NOTE: Statements and opinions advanced in papers are to be understood as individual expressions of their authors and not those of the Society. Manuscript received at ASME Headquarters, February 24, 1959.Paper No. 59, IRD-11.
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This paper presents an economic and automatic experimental technique that allows the determination of the equivalent circuit of aluminum electrolytic capacitors. To implement the proposed technique it is necessary to arrange experimentally the capacitor under test in series with a resistor and connected to a sinusoidal voltage. The relationship between gain and phase of the sinusoidal voltage waveform applied to both capacitor and resistor, and the gain and phase of capacitor voltage give enough information to compute the capacitors equivalent circuit. To obtain both gain and phase of both waveforms with high accuracy, the discrete Fourier transform algorithm is used.
The aim of this paper is to present an experimental off-line technique that can be used to estimate the condition of aluminum electrolytic capacitors. The aging of aluminum electrolytic capacitors is expressed by the increase of their equivalent series resistance (ESR) and the reduction of their capacitance. Thus, the proposed technique is based in the estimation of both ESR and capacitance values. To validate the theoretical equations some experimental and simulated results will be presented.
Electrolytic capacitors are responsible for frequent breakdowns of static converters. A new DSP based method, to set a predictive maintenance, is presented. Signature of changes in capacitance and ESR, due to aging, will reflect in capacitor ripple voltage and current; and these changes are monitored using proposed method to predict the future status of the capacitor
One of the most frequent reasons of breakdown of static power
converters, and in particular switch mode power supplies, is the failure
of filter electrolytic capacitors. With the use of time-worn capacitors,
or by modelling the faults artificially, the authors have developed a
fault indicator. By comparing the latter with data representing the
system during normal running, they have achieved an estimate of imminent
failure
Common failure modes of aluminum electrolytic capacitors are due to chemical reactions between electrodes and electrolyte. From capacitance and weight change data and electron micrographs it is proposed that the attack of anode foil is primarily dissolution of oxide dielectric; that of cathode foil involves metal dissolution with hydrogen evolution.
The convergence properties of a fairly general class of adaptive
recursive least-squares algorithms are studied under the assumption that
the data generation mechanism is deterministic and time invariant.
First, the (open-loop) identification case is considered. By a suitable
notion of excitation subspace, the convergence analysis of the
identification algorithm is carried out with no persistent excitation
hypothesis, i.e. it is proven that the projection of the parameter error
on the excitation subspace tends to zero, while the orthogonal component
of the error remains bounded. The convergence of an adaptive control
scheme based on the minimum variance control law is then dealt with. It
is shown that under the standard minimum-phase assumption, the tracking
error converges to zero whenever the reference signal is bounded.
Furthermore, the control variable turns out to be bounded
Detection of faults of filter capacitors in a converter. application to predictive maintenance
- P Venet
- H Damand
- G Grellet
Sliding Mode Control - Theory and Applications
- edwards
Technical Manual on Aluminum Capacitors: introduction, basic concepts, and definitions
- Vishay Roederstein