RU2406176C1 - Quality control method for capacitors with double electric layer - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: increasing charging voltage is supplied to the capacitor being tested and dependency of internal capacitor resistance on increasing voltage charge is plotted. After that maximum voltage is determined as corresponding abnormality on the said dependency. Based on maximum voltage value, capacitor quality is defined by it's comparing with the allowable standard values.

EFFECT: improved quality control of capacitors with double electric layer.

1 dwg

Description

The invention relates to electrical and electronic equipment and can be used in the design and manufacture of capacitors with a double electric layer (DEL), in particular in the manufacture of capacitor energy storage devices (NE).

A known method of controlling the quality of electrolytic capacitors, including supplying a rising charge voltage to the test capacitor to a predetermined value and holding at this voltage for 3-10 hours. Capacitors are subject to rejection, in which during the exposure period an electric breakdown of the dielectric layer on the electrode will occur (USSR author's certificate No. 455385, M.cl. H01G 13/00, publ. 1973). The disadvantages of this method are the impossibility of its use for capacitors with a double electric layer with aqueous electrolytes, in which there is no electrical breakdown due to the absence of a dielectric layer on the electrodes, as well as the long test time and the inability to determine the cause of marriage.

The closest to the object to be sown, according to the totality of features, is a method for monitoring the quality of capacitors, including applying a charging rising voltage to the tested capacitor connected in series with the active resistance, and monitoring by detecting capacitors with an anomalous type of time dependence of the rising voltage on the capacitor (USSR author's certificate No. 942183 , M.cl. H01G 9/24, publ. 1982 - taken as a prototype). Suitable are capacitors in which for a given charge time a specified limit voltage is reached. With increased leakage current (I _y ) this condition is not satisfied and the capacitor is rejected. This control method has insufficient accuracy associated with the spread of the electrical parameters of the cells in multi-cell capacitors. Since the quality of the capacitor is determined by the actual value of the leakage current, it is possible to get a wrong idea about the quality due to the fact that the large leakage current of defective cells can be masked by the background of small leakage currents of high-quality cells. In addition, this method cannot determine the cause of the marriage.

An object of the invention is to improve the accuracy of quality control of capacitors with a double electric layer.

The technical result is achieved by the fact that in the method of controlling the quality of capacitors with a double electric layer, including supplying a charging rising voltage to the tested capacitor, the dependence of the value of the internal resistance of the capacitor on the rising voltage of the charge is built, the value of the maximum charge voltage is determined by the anomaly on the specified dependence, and by the value the maximum voltage determines the quality of the capacitor by comparing with the permissible norm.

The invention improves the accuracy of the quality control of capacitors due to the fact that two new control parameters are used - the maximum charge voltage and the nature of the dependence of internal resistance on the charge voltage. By the nature (type) of this dependence (increasing, decreasing, monotonic, nonmonotonic), one can determine the possible reason that limits the value of the maximum charge voltage.

The control method is as follows.

The test capacitor is connected to a direct current source and to a circuit for measuring voltage (U) and internal resistance (Z); include alternating current with an amplitude of not more than 1 A and a frequency of 1 kHz for measuring internal resistance; increase the DC voltage to an acceptable value (U _d ); using a plotter, build the dependence Z (U); determine the maximum charge voltage (U _max ) corresponding to the start of gas evolution in the capacitor; compare the value of U _max c U _d ; the quality of the capacitor is considered satisfactory if U _{max is} greater than or equal to the value of U _d . The capacitor test duration is 10 minutes.

Example

Two capacitor energy storage devices of the type 200PP-18 / 0.31, No. 254 and No. 256, manufactured at ZAO ELIT (Kursk) and meeting the standards of technical conditions, were tested by the claimed method. The capacitors were supplied with an increasing DC voltage of up to 212 and 242 V, respectively, and a plotter was used to plot the dependence of the internal resistance on the charge voltage. According to the figure, the graphs of the indicated dependence had characteristic sharp breaks, respectively, at voltages of 198 and 240 V, at which gas evolution in the capacitors begins. These voltages are maximum (U _max ), to which capacitors can be charged without negative consequences.

According to technical conditions, these NEs must have an internal resistance (Z) of no more than 310 mOhm, the permissible charge voltage (U _d ) is at least 210 V. According to the figure, the value of Z for both NEs complies with the standards. At the same time, NE 254 has U _max less than U _d , and, therefore, its quality is unsatisfactory. NE # 256 has U _max more than U _d , and therefore its quality is satisfactory.

According to the decreasing dependence Z (U), the reason for the small value of U _max at NE 254 is the shorting of capacitor cells. The number of shorting contacts and their area increase with increasing charge voltage due to the mutual attraction of the electrodes in the cells. Shorting leads to redistribution of voltage between buried and unburied cells, to overvoltages in unshortened cells and premature gas evolution in them.

An increase in the internal resistance of NE No. 256 with an increase in the charging voltage is associated with a decrease in the cross-sectional area of the through pores in the separators due to the mutual attraction of the electrodes.

The claimed method was used to control experimental capacitor energy storage devices with nominal charge voltages from 14 to 200 V, which were found to be suitable for monitoring them according to previously used parameters (electric capacitance, internal resistance, leakage current, and insulation resistance). In individual batches of these NEs, after control by the claimed method, up to 50% of NEs were rejected, while during control by previously applied methods, no more than 10%.

Thus, the claimed method improves the accuracy of quality control of capacitors with a double electric layer by 40%.

Claims (1)

A method for controlling the quality of capacitors with a double electric layer, comprising supplying a charging rising voltage to the tested capacitor, characterized in that the dependence of the value of the internal resistance of the capacitor on the rising voltage of the charge is determined, the maximum voltage corresponding to the anomaly in the specified dependence is determined, and the maximum voltage is determined quality of the capacitor by comparing it with an acceptable norm.