JPH0451789B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a deterioration detection device for electrolytic capacitors.

[Prior Art] Figure 3 is a conceptual diagram of a conventional electrolytic capacitor deterioration detection device disclosed in Japanese Patent Application No. 60-257100.
In the figure, 1 is an electrolytic capacitor, 2 is a discharge resistor, 3 is a voltage divider, 4 is an on/off switch, 5 is a first-order lag calculator incorporating a variable resistor 5a and a variable capacitor 5b, 6 is a signal discriminator, and 7 is an alarm.

Next, the operation of the above configuration will be explained. For safety purposes, the electrolytic capacitor 1 is normally provided with a discharge resistor 2 having a relatively large resistance value at its terminal so that the capacitor 1 does not retain a charge and has no potential unless it is in use. A voltage dividing circuit 3 is provided in parallel with the discharge resistor 2 to divide the voltage to a reasonable voltage value as an input to a computing unit 5, which will be described later. One of the signals from the voltage dividing circuit 3 is inputted to an arithmetic unit 5 which can adjust the temporary delay time through a switch 4 which is normally closed and is opened when deterioration is determined. The voltage attenuation characteristic of the calculator 5 is that when the switch 4 is closed and the electrolytic capacitor 1 is charged at the rated voltage, when the switch 4 is opened, the electrolytic capacitor 1
It is adjusted by the variable resistor 5a and the variable capacitor 5b so as to match the discharge characteristics determined by the capacitance and the discharge resistor 2 when it is determined that the discharge voltage is deteriorated.

Thus, the output signal of the arithmetic unit 5 and the signal from the voltage dividing circuit 3 are input to the discriminator 6. The discriminator 6 detects the discharge characteristics transiently determined by the capacitance C (F) of the capacitor 1 and the resistance value R (Ω) of the discharge resistor 2 (reference numeral 11 in FIG. 2) and the deterioration created by the operational amplifier 5. A discharge characteristic (reference numeral 12 in FIG. 2) equivalent to that at the initial stage is compared, and when the attenuation of the discharge characteristic 11 becomes faster than the attenuation of the discharge characteristic 12, an output is output and the alarm 7 is driven.

[Problems to be solved by the invention] Since the conventional electrolytic capacitor deterioration device is configured as described above, it requires circuit components such as a first-order lag calculator and a signal discriminator, and also requires aging of these components. Changes also need to be taken into consideration, and both economic efficiency and reliability were not satisfactory.

This invention was made to solve the above-mentioned problems, and aims to provide an inexpensive and highly reliable deterioration detection device for electrolytic capacitors.

[Means for Solving the Problems] The deterioration detection device for an electrolytic capacitor according to the present invention stores the discharge characteristics of the electrolytic capacitor and the discharge resistor in a recording device at the initial stage of the product (for example, during a factory test), and when the device starts to be used. After that, the discharge characteristics of the electrolytic capacitor and the discharge resistor are compared each time with the discharge characteristics of the initial product, and if the difference exceeds a preset rated value, a deterioration detection indication is displayed.

[Function] The deterioration detection device for an electrolytic capacitor according to the present invention can determine the capacitance of an electrolytic capacitor from the voltage change of a resistor provided for discharging the electric charge charged in the electrolytic capacitor, and can detect the capacitance over time. Deterioration can be detected from the amount of change.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. In Figure 1, 1 is an electrolytic capacitor, 2 is a discharge resistor, 3 is a voltage divider, and 21 is an analog/
a digital converter; 22 is an arithmetic unit consisting of a CPU, etc.;
23 is a storage device consisting of ROM, and 7 is an alarm device.

Next, the operation of the embodiment having the above configuration will be explained. For safety purposes, the electrolytic capacitor 1 is normally provided with a discharge resistor 2 having a relatively large resistance value at its terminal so that a charge remains in the capacitor 1 and does not have a potential when the capacitor 1 is not in use. A voltage dividing circuit 3 is provided in parallel with this discharge resistor, and an A/D converter 21 to be described later.
Divide the voltage to a reasonable voltage value as an input. The signal from the voltage dividing circuit 3 is converted from an analog signal to a digital signal by the A/D converter 21 and read into the arithmetic unit 22 . Here, the calculation device 22 calculates the transient discharge characteristics when the electrolytic capacitor deteriorates from the transient discharge characteristics at the first stop during the factory test, and stores the contents in the storage device 23. During the second and subsequent stops, the arithmetic device 22 compares the signal from the A/D converter 21 (reference numeral 11 in FIG. 2) and the signal from the storage device 23 (reference numeral 12 in FIG. 2), and determines the discharge characteristics. When the attenuation of the discharge characteristic 11 becomes faster than the attenuation of the discharge characteristic 12, an output is output and the alarm 7 is driven.

In the above embodiment, the contents of the storage device 23 are set to values assuming a state of deterioration; however, the values of the discharge characteristics at the time of the first stop may be used instead of the values assuming a state of deterioration. In this case, the deterioration coefficient may be taken into consideration in the calculation process for each stop after the second time.

[Effects of the Invention] As described above, according to the present invention, a storage device is provided that stores in advance the discharge characteristics of an electrolytic capacitor with a discharge resistor connected to both ends at the initial stage of the product, and a calculation device , the electrolytic capacitor is configured to input the discharge voltage at the time of discharging the electrolytic capacitor, and determine that the electrolytic capacitor has deteriorated when the attenuation of the discharge voltage is greater than the attenuation of the discharge characteristics stored in the storage device. Therefore, it is possible to determine the deterioration of the electrolytic capacitor without installing a first-order lag calculator or signal discriminator, which eliminates the need to consider aging of the first-order lag calculator, etc., and has the effect of obtaining high accuracy. There is.

[Brief explanation of the drawing]

Fig. 1 is a conceptual diagram of an electrolytic capacitor deterioration detection device according to an embodiment of the present invention, Fig. 2 is a discharge characteristic diagram of an electrolytic capacitor and a discharge resistor, and Fig. 3 is a conceptual diagram of a conventional electrolytic capacitor deterioration detection device. It is a diagram. 1 is an electrolytic capacitor, 2 is a discharge resistor, 22 is an arithmetic device, and 23 is a storage device. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] 1. An electrolytic capacitor with a discharge resistor connected to both ends and charged with an electric charge, and a storage device that stores in advance the discharge characteristics of the electrolytic capacitor with the discharge resistor connected to both ends at the initial stage of the product. and an arithmetic device that inputs the discharge voltage during discharge of the electrolytic capacitor and determines that the electrolytic capacitor has deteriorated when the attenuation of the discharge voltage is greater than the attenuation of the discharge characteristics stored in the storage device. A deterioration detection device for electrolytic capacitors.