JPS63228917A - Defect identification circuit for source ripple eliminating electrolytic capacitor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention detects ripples that increase due to deterioration of an electrolytic capacitor for removing ripples after rectification in a power supply circuit that rectifies alternating current to generate direct current, and provides an alarm. The present invention relates to a defect determination circuit for electrolytic capacitors for removing power supply ripples, which is suitable for use in power supply ripple removal.

[Conventional technology]

Aluminum electrolytic capacitors are widely used to remove ripples after rectification in conventional power supply circuits that rectify alternating current to generate direct current. However, aluminum electrolytic capacitors have a shorter lifespan than other circuit components, and are prone to circuit failure due to capacity reduction due to evaporation (dry-up) of the internal electrolyte in aluminum electrolytic capacitors. This has also been pointed out for switching power supplies that have a power supply circuit that rectifies alternating current to generate direct current, but it has not been possible to actually determine the quality of electrolytic capacitors.

Note that a device for detecting this type of capacitor failure is described in Japanese Utility Model Publication No. 37-6230.
This is a monitoring device for a capacitor trip device that mainly detects disconnection in a capacitor circuit.The method and device for detecting a disconnection in a capacitor circuit includes an auxiliary transformer and a failure disconnection device, and detects deterioration of the capacitor and issues an alarm. No consideration has been given to the

[Problem that the invention seeks to solve]

The above conventional technology detects disconnection of the capacitor circuit in a capacitor trip device, but does not take into account the detection of deterioration of the capacitor. It is not possible to determine the quality of the electrolytic capacitor for ripple removal by detecting its deterioration.

The purpose of the present invention is to prevent the life of electrolytic capacitors and circuit failures by detecting the deterioration of electrolytic capacitors and determining whether they are good or bad. An object of the present invention is to provide a defect determination circuit for an electrolytic capacitor for removing power supply ripples, which can improve reliability.

[Means for solving problems]

The above objective is to focus on the fact that in an AC/DC conversion circuit that has an electrolytic capacitor for removing power supply ripples, if the electrolytic capacitor for removing power supply ripples deteriorates due to dry-up etc., the ripples contained in the DC after AC rectification increase. This is achieved by a defect determination circuit for an electrolytic capacitor for removing power supply ripple, which is equipped with a ripple voltage detection circuit that detects the difference between the high and low ripple voltages to monitor the increase in ripple and issue an alarm.

[Effect]

In the defect determination circuit for the electrolytic capacitor for removing power supply ripples, the ripple voltage of the electrolytic capacitor for removing power supply ripples is detected by the ripple voltage detection circuit, the ripple voltage detection signal is integrated by, for example, an integrating circuit, and the integrated voltage level is The signal can drive a pass/fail determination signal output circuit to issue an alarm. In this case, the ripple voltage detection circuit has two sets of circuits that divide the voltage across the electrolytic capacitor for removing power supply ripples with a resistor, and the resistor-divided one is provided with a capacitor to maintain its peak voltage, and the voltage division ratio is the resistor. Voltage only is set to have a higher divided voltage.

These two divided voltages are input to a voltage comparator, and a ripple voltage detection signal is output from the voltage comparator.

Such a resistive voltage divider circuit allows for a wide range of DC voltages after AC rectification. Then, since the ripple voltage detection signal becomes a pulse-like signal synchronized with the troughs of the ripple voltage, it becomes a voltage level signal when integrated by an integrating circuit. Such an integrating circuit prevents erroneous detection during momentary power outages or when power is turned on. When the output voltage level of this integrating circuit exceeds a predetermined voltage, an output circuit for a pass/fail determination signal is activated to warn that the electrolytic capacitor for removing power supply ripples has deteriorated.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

FIG. 1 is a circuit diagram showing an embodiment of a defect determination circuit for an electrolytic capacitor for removing power supply ripples according to the present invention. 1st
In the figure, the defect judgment circuit of the electrolytic capacitor for power supply ripple removal consists of a ripple voltage detection circuit, an integration circuit for the ripple voltage detection signal, and an output circuit for the pass/fail judgment signal. The voltage across the power supply ripple removal capacitor is input.

The ripple voltage detection circuit has two sets of resistance voltage dividing circuits consisting of voltage dividing resistors 1 and 2 and voltage dividing resistors 3 and 4 connected between input terminals, and one set of resistance voltage dividing circuits consisting of voltage dividing resistors 3 and 4. In the voltage circuit, a ripple removal capacitor 5 is provided in parallel with the voltage dividing resistor 4 in order to hold the divided peak voltage. The voltage dividing ratio of these two sets of resistance voltage dividing circuits is set so that the voltage divided by the voltage dividing resistors 1 and 2 is higher than the voltage divided by the voltage dividing resistors 3 and 4.

The voltage divided by the voltage dividing resistors 1 and 2 of the two sets of resistor voltage dividing circuits, the voltage divided by the voltage dividing resistors 3 and 4, and the divided voltage from which ripples are removed by the capacitor 5 are transferred to the transistors of the differential amplifier forming the voltage comparator. 6 and the base of transistor 7, respectively, and the output of this differential amplifier becomes a ripple voltage detection signal. The resistor 20 is the transistor 6.7 of the differential amplifier.
is the emitter resistance of

A Zener diode 8 is connected to the load of the transistor 7 of this differential amplifier, and the base of a transistor 10 in the next stage is connected, and the transistor 10 in the next stage and the emitter resistor 9 form a constant current circuit. A parallel path of a storage capacitor 11 and a resistor 22 forming an integrating circuit is connected to the load of the transistor 10 of this constant current circuit via a diode 21, and when transistors 1 to 10 are turned on, the capacitor 11 is charged with a constant current. . Since the ripple voltage detection signal is a pulse signal synchronized with the valley of the ripple, this pulse signal is integrated by an integrating circuit and converted into a voltage level signal, and the voltage level signal of the capacitor 11 of this integrating circuit is output as a pass/fail judgment signal. The voltage is applied to the gate 1- of a thyristor (triac) 12 forming the circuit, and when the voltage of the capacitor 11 increases and exceeds the turn-on voltage of the thyristor 12, the thyristor 12 sends an alarm to an indicator lamp, buzzer, etc. connected to the output terminal.

FIG. 2 is a waveform example diagram of each part for explaining the operation of FIG. 1. In Fig. 2, first, if the power supply ripple removal capacitor connected to the input terminal in Fig. 1 is of good quality, the divided voltage A due to the voltage dividing resistors 1 and 2 of the resistor voltage divider circuit is the solid line in Fig. 2. As shown in , the ripple voltage included in the DC after AC rectification, that is, the height difference between the peak and valley voltage levels of the ripple, is a normal value. Since the divided voltage B from which the ripple component caused by 5 has been removed is set lower than the divided voltage A, it has a constant voltage level as shown by the dashed line in FIG. In this way, since the divided voltage A is always at a higher voltage level than the divided voltage B, the differential amplifier is in a state where the transistor 6 is on and the transistor 7 is off. Therefore, since the transistor 7 is off, the next stage transistor 10 is also turned off, and at this time, the voltage across the capacitor 11 of the integrating circuit becomes zero V, and the thyristor (triac) 12 of the output circuit is turned on.

Next, if the power supply ripple removal capacitor connected to the input terminal deteriorates, the divided voltage AI by the voltage dividing resistor 1.2 will be included in the DC after AC rectification, as shown by the broken line in Figure 2. The ripple voltage increases and the valley of the ripple becomes an abnormally low value, and the divided voltage B by one of the voltage dividing resistors 3 and 4 is held at the peak value by the capacitor 5 and becomes approximately the same voltage level. Comparing divided voltage A and divided voltage B in this way, at the valley of the ripple, divided voltage A/
There is a period when the voltage level is lower than the divided voltage B,
During this period, the transistor 7 of the differential amplifier is turned on, so the next stage transistor 10 is also turned on, which causes the second
The Zener diode 8 of the load and the transistor 1 of the next stage are connected by the pulse wave ripple voltage detection signal of the differential amplifier synchronized with the valley of the ripple of the divided voltage A/ as shown in the figure.
The constant current C determined by the emitter resistance 9 of 0 is the diode 2.
1 to the capacitor 11 of the load integration circuit and charges the capacitor 11. Capacitor 1 of this integrating circuit
The voltage level across the resistor 1 gradually increases each time a pulse wave-like constant current C flows into the resistor 22, and when this integrated voltage level reaches the turn-on voltage of the thyristor 12 in the output circuit, the thyristor 12 is turned on. A defective determination signal is output to the output terminal. Therefore, if an indicator lamp or a buzzer is connected to the output terminal, the deterioration of the power supply ripple removal capacitor connected to the input terminal can be detected by an alarm.

According to this embodiment, the input of the differential amplifier is given unstabilized using a resistive voltage dividing circuit using voltage dividing resistors, and
Since the capacitor of the integrating circuit is powered by a constant current, it is not affected by fluctuations in the power supply.

It can operate over a wide voltage range for DC voltage after AC rectification, and can be used alone as a measuring device.

FIG. 3 is a block diagram of an AC/DC converter circuit showing an embodiment of the power supply ripple blocking capacitor defect determination circuit according to the present invention. In FIG. 3, an AC/DC conversion circuit that rectifies AC from an AC power source 23 and converts it into DC by a rectifier 13 has a power supply ripple removal capacitor 14 for removing ripples contained in the DC after AC rectification. A power ripple blocking capacitor defect determination circuit 15 as shown in FIG. 1 which receives the voltage across the power ripple blocking capacitor 14 as input is inserted into the DC output of the rectifier 13 of this AC/DC converter circuit, and its output is is alarm 16
When the relays 17 are connected in parallel and the relays 17 operate, the relay contacts close, and the reserve capacitor 18 functions as an electrolytic capacitor for removing power supply ripples. resistance 1
Reference numeral 9 denotes a preparatory capacitor deterioration prevention resistor for applying voltage to the preparatory capacitor 18 to prevent it from deteriorating due to natural neglect, and for preventing current from flowing to the preparatory capacitor 18 and deteriorating it when the relay 17 is off.

In this AC/DC conversion circuit, when the power supply ripple removal electrolytic capacitor 14 for removing ripples in the DC output obtained by rectifying the AC input of the AC power supply 23 by the rectifier 13 deteriorates, the ripples increased due to the deterioration of the electrolytic capacitor 14 The voltage is detected by the main power supply ripple removal capacitor defect judgment circuit], 5, and the output activates the alarm 16 to issue an alarm. At the same time, the relay 17 is turned on to charge the spare capacitor 18 through the relay contact, thereby reducing the power supply. Since it functions as an electrolytic capacitor for removing ripples, even if the recognition of the defective judgment alarm of the electrolytic capacitor 14 is delayed, no failure will occur.

According to this embodiment, the ripple voltage of the electrolytic capacitor for removing ripples from the DC output of the AC/DC converter circuit is monitored, and deterioration due to dry-up of the electrolytic capacitor is detected due to an increase in the ripple voltage, and a defect is determined before the end of its life. Since the capacity can be increased with a spare capacitor at the same time as an alarm is issued, it is particularly effective for power supply circuits that require high reliability such as for emergency use, and power supply circuits that cannot be converted immediately even if deterioration of the electrolytic capacitor is discovered.

〔Effect of the invention〕

According to the present invention, deterioration of an electrolytic capacitor for removing power supply ripples can be detected before it reaches the end of the life of the capacitor or a failure of the circuit, so that downtime of the power supply circuit can be minimized and reliability of the power supply circuit can be improved.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an embodiment of a failure determination circuit for electrolytic capacitors for power supply ripple removal according to the present invention, Fig. 2 is an example of operation waveforms of each part of Fig. 1, and Fig. 3 is a power supply ripple removal according to the present invention. FIG. 2 is a block diagram of an AC/DC conversion circuit showing an embodiment of a defect determination circuit for an electrolytic capacitor. 1 to 4...Voltage dividing resistor, 5. Capacitor, 6, 7...
Differential amplification transistor, 8... Zener diode,
9... Resistor, 10... Transistor, 11... Integrating capacitor, 12... Output thyristor, 13...
- Rectifier, 14... Electrolytic capacitor for power supply ripple removal, 15... Defective judgment circuit for electrolytic capacitor for power supply ripple removal, 16... Alarm, 17... Relay, 18
... Reserve capacitor, 19, 20.22... Resistor,
21...Diode, 23...AC power supply. Figure 1

Claims (1)

[Claims] 1. In an AC/DC converter circuit having an electrolytic capacitor for power supply ripple removal, a ripple voltage detection circuit is provided to monitor the increase in ripple due to dry-up of the power supply ripple removal electrolytic capacitor, etc., and to issue an alarm. Features a defective judgment circuit for electrolytic capacitors for removing power supply ripples.