JP2010093046A - Life prediction method and device for electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a life prediction method for an electrolytic capacitor that can predict an accurate life of the electrolytic capacitor used for a control board. <P>SOLUTION: The life prediction method includes a detachment step of detaching the electrolytic capacitor attached to the control board whose use elapsed period can be specified, a measurement step of measuring electrostatic capacitance and tanδ of each of the detached capacitor and a new electrolytic capacitor which has the same standard with the detached electrolytic capacitor, a calculation step of calculating a temperature rise ΔT of each of the electrolytic capacitors from measured electrostatic capacitance and tanδ, and a prediction step of predicting a temperature rise up to a temperature at which the electrolytic capacitance or tanδ of the detached electrolytic capacitor reaches an abnormal value and then predicting a period when the detached electrolytic capacitor has an abnormal value based upon the predicted temperature rise in accordance with the Arrhenius law. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electrolytic capacitor life prediction method and apparatus, and more particularly to an electrolytic capacitor life prediction method and apparatus used in a control board.

  Most control boards are equipped with electrolytic capacitors for voltage smoothing and noise removal. However, the electrolytic capacitor is a long-life product having such characteristics that the internal electrolyte causes dry-up due to permeation and scattering, thereby causing a decrease in capacitance. In many cases, it is the only product with a limited life on the control board, and the life of the electrolytic capacitor directly leads to the life of the control board.

  Further, the life estimation of the conventional aluminum electrolytic capacitor is based on the Arrhenius model equation (described later), that is, the idea that the life is halved every time the operating temperature rises by 10 ° C. is used.

In Patent Document 1 or Patent Document 2, in a large-capacity electrolytic capacitor, a capacitor deterioration degree curve is plotted by continuously measuring the capacitance / resistance value, and the deterioration degree of the capacitor is determined. Is disclosed.
JP 2002-25872 A JP 2001-76980 A

  However, the electrolytic capacitor on the control board cannot predict the temperature change of the capacitor due to the surrounding resistance or the heat generated by the capacitor itself. There is a problem that it is actually difficult to estimate the lifetime of the electrolytic capacitor from the standard capacitor deterioration degree prediction curve.

  In addition, the electrolytic capacitor on the substrate is precisely soldered together with other elements, and it is impossible to create a capacitor deterioration degree curve using the measured value of the capacitor as in the technique disclosed in Patent Document 1 or 2. Until now, the life prediction of the electrolytic capacitor on the substrate has not been carried out.

  For this reason, under the present circumstances, the corresponding Breakdown Maintenance (hereinafter referred to as BM correspondence) after the failure of the substrate, simultaneous replacement after the estimated life (about 10 years) or more, and substrate overhaul using a spare substrate (Hereinafter referred to as OH correspondence).

  However, even with these methods, there are the following problems in steelworks where the total number of substrates is several thousand and the same standard substrate is several tens or more. That is, if the substrates reach the end of their lives at the same time, there is a possibility of a shortage of spare substrates / manufacturer inventory, and if these allowances are not met in time, there is a risk of leading to a factory shutdown. In addition, even when the life is estimated in a safe direction and the board is renewed at an early stage, it is necessary to purchase a huge quantity of high-priced control boards, which requires a huge repair cost. is there.

  An object of the present invention is to provide an electrolytic capacitor life prediction method and apparatus capable of accurately predicting the life of an electrolytic capacitor used in a control board in view of these problems of the prior art.

  The invention according to claim 1 of the present invention is an electrolytic capacitor life prediction method for predicting the life of an electrolytic capacitor used on a control board, and removing the electrolytic capacitor attached to the control board capable of specifying the elapsed usage period. Measuring step of measuring capacitance and tan δ for each of the step, the removed electrolytic capacitor, and a new electrolytic capacitor of the same standard as the electrolytic capacitor, and the temperature of each electrolytic capacitor from the measured capacitance and tan δ Using the calculation step for calculating the increase ΔT and the calculated temperature increase ΔT, the temperature increase until either the capacitance of the removed electrolytic capacitor or tan δ becomes an abnormal value is predicted, and the predicted temperature increase And a prediction step for predicting when the removed electrolytic capacitor becomes abnormal based on the Arrhenius law. This is a method for predicting the lifetime of an electrolytic capacitor.

  According to a second aspect of the present invention, in the electrolytic capacitor life prediction method according to the first aspect, the temperature rise ΔT is obtained from the following equation (3): Is the method.

  Furthermore, the invention according to claim 3 of the present invention is an electrolytic capacitor lifetime predicting apparatus for predicting the lifetime of an electrolytic capacitor used on a control board, the electrolytic capacitor removed from the control board capable of specifying the elapsed usage period, For each new electrolytic capacitor of the same standard as the electrolytic capacitor, a measuring means for measuring the capacitance and tan δ, and the capacitance and tan δ measured by the measuring means are input, and the temperature rise ΔT of each electrolytic capacitor And calculating the temperature rise ΔT calculated by the calculation means, predicting the temperature rise until either the capacitance of the removed electrolytic capacitor or tan δ becomes an abnormal value, and predicting the temperature And a predicting means for predicting when the electrolytic capacitor removed becomes abnormal based on the Arrhenius law. This is a device for predicting the life of a decoupling capacitor.

  According to the present invention, it is possible to accurately predict the lifetime of the electrolytic capacitor used in the control board, and thus it is possible to obtain information on the degree of deterioration of the board that has been unknown until now. Furthermore, by estimating the degree of deterioration of the control board that has not been updated yet in the same standard and the same environment from the degree of deterioration of the board, the effect of lowering the renewal cost due to the prevention of failure troubles and adjustment of the renewal time can be achieved. can get.

  FIG. 5 is a diagram illustrating the configuration of the electrolytic capacitor. Electrolytic capacitors can be broadly classified into aluminum electrolytic capacitors and tantalum electrolytic capacitors. In FIG. 5, an example of an aluminum electrolytic capacitor will be described.

  The tantalum electrolytic capacitor has a very stable chemical film and little deterioration. Compared to an aluminum electrolytic capacitor, the tantalum electrolytic capacitor has a low leakage current, a long life and high reliability, but is expensive. For this reason, aluminum electrolytic capacitors are widely used in the industry.

  An aluminum electrolytic capacitor is formed by forming a dielectric oxide film on a roughened aluminum anode and then winding it together with an aluminum cathode with a separator (electrolytic paper containing an electrolyte such as ammonium borate) interposed between them. Thus, a capacitor element is formed. And after accommodating this capacitor | condenser element in a bottomed cylindrical aluminum case, it is comprised by sealing the open end of this aluminum case with the sealing member which consists of elastic bodies, such as rubber | gum.

  In the aluminum electrolytic capacitor configured in this manner, the aluminum case containing the capacitor element impregnated with the electrolytic solution is sealed with a sealing member made of an elastic material such as rubber, so that it is completely sealed. Is difficult. For this reason, the electrolyte solution gradually evaporates with the passage of time, and there is a problem that important electrical characteristics as an aluminum electrolytic capacitor deteriorate, such as a decrease in capacitance and an increase in tan δ (loss angle). is doing.

  The tan δ (loss angle) described above has a relationship represented by the following equation (1).

  In estimating the life of an aluminum electrolytic capacitor, it is known to follow the Arrhenius model equation shown by the following equation (2).

  Since the evaporation rate of the electrolytic solution is approximated to be doubled every time the temperature rises by 10 ° C., the lifetime is reduced by half every time the operating temperature rises by 10 ° C.

  However, in the electrolytic capacitor on the control board, as described above, the temperature change of the capacitor cannot be predicted or measured successfully, and the Arrhenius model formula cannot be directly applied.

  In the present invention, in the situation where the temperature of the capacitor is unknown and the capacitor deterioration degree prediction curve cannot be measured and created, it is determined how long the capacitor can be used from the amount of deterioration of the capacitor performance and the period of use of the capacitor. It is to be predicted.

  Up to now, when requesting manufacturers to handle OH on the control board, replacement of limited-life products such as electrolytic capacitors and batteries on the control board, and operation tests have been conducted to see if there are any deteriorations or problems. The inventors of the present invention paid attention to a used electrolytic capacitor that was discarded as it was when replacing a limited-life product.

  That is, the capacitance / tanδ value of the electrolytic capacitor that has been discarded so far is measured, and the temperature rise of the capacitor is based on the measured capacitance / tanδ value and the capacitance / tanδ value of a new electrolytic capacitor. By calculating how much has increased, it is predicted how long it can be used from the previous period of use.

  FIG. 2 is a diagram showing a configuration example of the electrolytic capacitor life prediction apparatus according to the present invention. The capacitance measurement unit 1 that measures the capacitance value of the electrolytic capacitor, the tan δ measurement unit 2 that measures the tan δ value of the electrolytic capacitor, and the values measured using the capacitance measurement unit 1 and the tan δ measurement unit 2 A ΔT calculation unit 3 that inputs and calculates the temperature rise amount ΔT of the electrolytic capacitor, a prediction calculation unit 4 that inputs the obtained ΔT to predict the life of the electrolytic capacitor, and an output unit 5 that displays the predicted result The

  Here, a commercially available measuring instrument may be used for the capacitance measuring unit 1 and the tan δ measuring unit 2. Measure electrolytic capacitors with a known usage period and new (unused) electrolytic capacitors of the same standard. Each measurement is performed twice, but until all the measurements are completed, the measured values up to that time are temporarily stored in the ΔT calculation unit, and when all the measurements are completed, the calculation of the ΔT calculation unit is performed. Just start. Further, the ΔT calculation unit 3 and the prediction calculation unit 4 may be different computers or may be configured by one computer.

  FIG. 1 is a diagram showing an example of a processing procedure of a method for predicting the lifetime of an electrolytic capacitor according to the present invention. In the present invention, it is assumed that there are a plurality of target control boards in the same specification.

  First, in Step 11, the electrolytic capacitor is removed from one of the electrolytic capacitors that are attached to the control board and used under the same specifications and under the same conditions. The implementation time may be OH correspondence or a specific time, but it is necessary to be able to specify the elapsed usage period (for example, n years).

  Next, in Step 12, the capacitance and tan δ are measured for each of the removed electrolytic capacitor and a new electrolytic capacitor of the same standard.

  In Step 13, the temperature rise ΔT of the capacitor is calculated based on the following equation (3) from the measured capacitance and tan δ.

  The capacitor temperature rise ΔT can be calculated for each electrolytic capacitor that has been used for n years and has been removed, and a new electrolytic capacitor of the same standard. The internal resistance R in the equation (3) is calculated from the measured capacitance and tan δ by modifying the above equation (1), and the other surface area, heat dissipation coefficient and ripple current are known or rated values. is there.

  FIG. 3 is a diagram showing an example of tan δ and the temperature rise of the capacitor. This is an example of a capacitor used for 10 years, the measured tan δ is 0.038, and the calculated temperature rise is + 16.1 ° C. This shows the state of acceleration of capacitor deterioration in which tan δ increases due to capacitor deterioration and the capacitor generates heat. In addition, the measured tan δ and the calculated temperature rise are 0.015 and + 6.4 ° C., respectively, for a new electrolytic capacitor of the same standard.

  In the figure, the portion where tan δ is 0.12 or more represents the failure range determined by the capacitor manufacturer. As tan δ increases due to the deterioration of the capacitor, and the increase in tan δ causes the capacitor to generate heat, the deterioration accelerates and enters the failure range.

  Returning to FIG. 1 and continuing the explanation, in the next Step 14, the time when the capacitor to be measured becomes an abnormal value is predicted from the calculated temperature rise of the capacitor. FIG. 4 is a diagram illustrating an example of predicting a time when an abnormal value occurs. The horizontal axis represents the capacitance change (based on the manufacturer's rated value), the vertical axis represents tan δ, and each of the electrolytic capacitor removed from the substrate and the new capacitor measured in Step 12 is plotted.

  A method for predicting the time when an abnormal value occurs in the example shown in FIG. 4 will be described. In the case of this example, it can be seen that the current value that has been used for 10 years from the new product is in an approximately middle position from the new product to the failure range (capacitance change -20% or less) determined by the capacitor manufacturer. After 10 years of use, the temperature rise is about 10 ° C. (16.1 ° C.−6.4 ° C.), and it can be predicted that the temperature rise will further increase by 10 ° C. due to the acceleration of deterioration before reaching the failure range. Therefore, based on the Arrhenius rule (the lifetime is halved every time the operating temperature increases by 10 ° C.), the lifetime from the current value can be predicted to be a half value of 10 years elapsed from the current value to 5 years.

  Incidentally, in FIG. 4, when the current value used for 10 years from the new product is about 1/3 from the new product to the failure range (capacitance change -20% or less) determined by the capacitor manufacturer. It can be predicted that the temperature rise will further increase by 20 ° C. due to the acceleration of deterioration until the failure range is reached. Therefore, based on the Arrhenius law, the lifetime from the current value can be predicted to be a half value of 2.5 years, which is a half of the elapsed period of 10 years until the current value.

  There are the following methods for obtaining the lifetime more finely. As shown in FIG. 4, the new product and the current value are plotted, and the straight line connecting the two is extended to reach the failure range, and the capacitance change and tan δ ((ΔC / C) a, tan δa) at the failure range arrival point a are obtained. . Using the obtained (ΔC / C) a and tan δa, the temperature rise at the time of failure is obtained from the above-mentioned formulas (1) and (3), and the obtained temperature rise is put into the Arrhenius model formula (2). Ask.

  Finally, in Step 15, the substrate is replaced at the time (life) predicted in the previous step.

  The OH of the control board that exceeded the manufacturer's recommended life of 7 to 10 years was implemented, and the degree of deterioration of the electrolytic capacitor on the board was measured. As a result, we were able to confirm capacitor degradation such as a decrease in capacitance and a small amount of liquid leakage, but it was well within the capacitance value determined by the manufacturer, and the lifetime was predicted by applying the present invention. I found that there was no need to update. Therefore, instead of costly renewal by purchasing a new substrate, it was possible to keep the cost low by performing OH in order using a spare substrate having a sufficient lifetime.

It is a figure which shows the example of a process sequence of the lifetime prediction method of the electrolytic capacitor which concerns on this invention. It is a figure which shows the structural example of the lifetime prediction apparatus of the electrolytic capacitor which concerns on this invention. It is a figure which shows an example of tan-delta and the temperature rise of a capacitor | condenser. It is a figure which shows the example of prediction of the time used as an abnormal value. It is a figure explaining the structure of an electrolytic capacitor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Capacitance measurement part 2 tan-delta measurement part 3 (DELTA) T calculation part 4 Prediction calculating part 5 Output part

Claims (3)

An electrolytic capacitor life prediction method for predicting the life of an electrolytic capacitor used on a control board,
Removal step of removing the electrolytic capacitor attached to the control board that can specify the elapsed usage period;
A measurement step of measuring the capacitance and tan δ for each of the removed electrolytic capacitor and a new electrolytic capacitor with the same standard as the electrolytic capacitor;
A calculation step of calculating a temperature rise ΔT of each electrolytic capacitor from the measured capacitance and tan δ;
The calculated temperature rise ΔT is used to predict a temperature rise until either the electrostatic capacity or tan δ of the removed electrolytic capacitor becomes an abnormal value, and the removed electrolytic capacitor based on the predicted temperature rise and the Arrhenius rule is A method for predicting the life of an electrolytic capacitor, comprising: a predicting step for predicting a time when an abnormal value occurs. In the electrolytic capacitor lifetime prediction method according to claim 1,
The method for predicting the lifetime of an electrolytic capacitor, wherein the temperature rise ΔT is obtained from the following equation (3).

An electrolytic capacitor life prediction device for predicting the life of an electrolytic capacitor used on a control board,
An electrolytic capacitor removed from the control board that can specify the elapsed usage period, and a measuring means for measuring the capacitance and tan δ for each of the new electrolytic capacitors in the same standard as the electrolytic capacitor,
Calculating means for inputting the capacitance and tan δ measured by the measuring means and calculating the temperature rise ΔT of each electrolytic capacitor;
Input the temperature rise ΔT calculated by the calculation means, predict the temperature rise until either the capacitance of the removed electrolytic capacitor or tan δ becomes an abnormal value, and remove based on the predicted temperature rise and Arrhenius law And a predicting means for predicting a time when the electrolytic capacitor becomes an abnormal value.

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