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Electrolytic Capacitor Degradation Monitoring using an On-line Parameter Estimation Scheme involving Sliding Mode Differentiators and a Kalman Filter
... 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. ...
... The proposed approaches only employ a mathematical model for the capacitor rather than a model of the system to which the capacitor is connected. The primary advantage of these approaches is that they are capable of achieving highly accurate estimations of both the ESR and capacitance, even under noisy conditions [47]. However, the requirement of the additional capacitor current sensor results in additional costs of the converter. ...
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.
... Even if this method is accurate and cheap, it is an offline monitoring method which cannot be used during the normal operating condition of the component. In [9] a high accuracy in the estimation of the health indicators of a capacitance has been achieved involving an additional capacitor current sensor, increasing the cost of the converter. Another health monitoring technique, regarding the diagnosis of the IGBT in power modules, is exhibited in [10]. ...
The Digital Twin (DT) technology is transforming the energy conversion industry by replicating in real-time the behavior of physical systems by means of high-fidelity digital models (DMs). Specifically, close monitoring of parameters influencing the health status of components prone to failure is essential for the application of predictive maintenance strategies. This capability is made achievable through the use of the DT concept and the advanced optimization algorithms introduced in this work. This paper presents the parameters’ estimation approach based on the DT method applied to 3-phase AC-DC switching converters. First, a Particle Swarm Optimization (PSO) algorithm is employed to estimate the characteristics of the L-type AC filter and the DC capacitance. The same approach has been repeated using the Genetic Algorithm (GA) and the Simulated Annealing (SA) as optimization algorithms. Balanced and unbalanced situations have been tested to demonstrate the robustness and feasibility of the proposal and the comparison between the three proposed optimization algorithms has been carried out. The results show the potential of the procedure for application in system identification and condition monitoring.
... Unfortunately, accurate knowledge of the value of the inductance included in the intermediate circuit is required, which can change during use. The authors in [11,16] propose using a Kalman filter to estimate both the capacitance and ESR of a capacitor. This solution is problematic due to the high computational complexity involved in performing matrix operations. ...
The article concerns the problem of capacitor diagnosis in a hybrid aircraft. Capacitors are one of the most commonly damaged components of electrical vehicle drive systems. The result of these failures is an increase in voltage ripple. Most known analytical methods are based on frequency spectrum analysis, which is time-consuming and computationally complex. The use of deep neural networks (DNNs) allows for the direct use of the measurement signal, which reduces the operating time of the overall diagnostic system. However, the problem with these networks is the long training process. Therefore, this article uses transfer learning (TL), which allows for the secondary use of previously learnt DNNs. To collect data to learn the network, a test bench with the ability to simulate a capacitor failure was constructed, and a model based on it was made in the MATLAB/Simulink environment. A convolutional neural network (CNN) structure was developed and trained by the TL method to estimate the capacitance of the capacitor based on signals from the Simulink-designed model. The proposed fault diagnostic method is characterised by a nearly 100% efficiency in determining capacitance, with an operating time of about 10 ms, regardless of load and supply voltage.
... In [9] another monitoring method is presented: the estimation of the ESR of the capacitances has been reached in a PV boost converter using tunnelling magneto-resistive (TMR) sensors. Similarly, in [10] a high accuracy in the estimation of the health indicators of a capacitance has been achieved involving an additional capacitor current sensor, increasing the cost of the converter. In [11] no additional hardware is required; however, the capacitance is evaluated injecting sinusoidal voltage signal to the output terminal of a DC-DC converter, which can cause redundances or disturbances in the system. ...
... In [9] a parameters estimation scheme for AEC is proposed through simulations. This scheme utilizes the sliding mode differentiators and Kalman filter for the online estimation of ESR and capacitance parameters of AEC under noisy conditions. ...
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.
... Traditional capacitance measurement techniques use the processing of signal time derivatives [18], which are susceptible to undesired noise issues. On the other hand, the APIA requires a simple series RC circuit as a dynamical system with resistance R and capacitance C parameters as shown in Figure 2. ...
Abstract Flexible capacitive sensor devices have gained attention because of their versatility and adaptability to several requirements. However, the proper implementation of those devices into flexible electronic systems imply some challenges related to the readout strategies necessary to adequately determine capacitance values. Usually, electronic circuits are used to develop signal conditioning and processing tasks, as well as estimation of parameters. In this study, a free‐of‐signal conditioning strategy for capacitance measurement based on an algebraic parameter identification approach is presented. Furthermore, flexible capacitors over polyethylene terephthalate substrates and polydimethylsiloxane as dielectric material are fabricated with the aim to validate the behaviour of the capacitance measurement method. Experimental results are compared with standard recursive least square technique as well as standard capacitance metre. Overall results demonstrate the good performance of the proposed approach.
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.
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
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".
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.
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.
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.
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.
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
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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.
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
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.
Technical Manual on Aluminum Capacitors: introduction, basic concepts, and definitions
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