JPH03293938A - Uninterruptiple power supply device - Google Patents

Abstract

PURPOSE:To enable remaining life of an electrolytic capacitor to be diagnosed without stopping a power supply device for a long time by detecting charging characteristics when the power supply device is operated without any load and by estimating electrostatic capacity of the electrolytic capacitor. CONSTITUTION:After a switch 11 is turned on and a switch 10 is turned off by a sequence control circuit 21 and then switching is made to power-feed by a direct-supply commercial power supply 1 without any interruption, a rectifier 3 is stopped, a battery connection switch is turned off, and only an inverter 8 is operated without any load with residual charge of an electrolytic capacitor 5 as an input. Charging characteristics of the electrolytic capacitor 5 at this time are detected by a voltage detector 22, which is fed to a remaining life detector. An electrostatic capacity C is estimated by voltage and charging time of the electrolytic capacitor 5. The electrostatic capacitor C and an electrostatic capacity C0 of initial value are compared and it is diagnosed that life expired when the electrostatic capacity was reduced remarkably.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention provides a stabilized alternating current circuit that receives alternating current power or direct current power from a storage battery and has a smoothing electrolytic capacitor in the direct current circuit. The present invention relates to an uninterruptible power supply that supplies electric power, and particularly to an uninterruptible power supply equipped with a means for diagnosing the remaining life of an electrolytic capacitor.

(Conventional technique*) Conventionally, inverter devices have been widely used as uninterruptible power supplies to supply uninterrupted power by inputting DC power from storage batteries even during commercial power outages, and the DC circuit usually has a smoothing function. Many large capacity electrolytic capacitors are used.

FIG. 4 is a block diagram showing an example of the above-described uninterruptible power supply device.

In the figure, 1 is a direct commercial power supply, 2 is a commercial power supply, 3 is a rectifier, 4 is a smoothing reactor, 5 is a smoothing electrolytic capacitor, 6 is a storage battery, and 7 is a storage battery 6 when the commercial power supply 2 is out of power.
8 is an inverter, 9 is an AC filter that improves the rectangular wave output of the inverter to a sine wave, and 10.11 is a static changeover switch (thyristor switch).

12 is a load. Always AC filter 9. Power is supplied to the load by the inverter 8 via the changeover switch 10.

When the inverter 8 is out of order or equipment maintenance/inspection is performed, the changeover switch 10 is switched to the changeover switch 11 without a momentary interruption to supply power from the direct commercial power supply 1, and after the failure is recovered or the maintenance/inspection is completed, the changeover switch is switched to the inverter 8 again. This allows continuous power to be supplied to the load.

Large-capacity electrolytic capacitors are generally used as smoothing capacitors in DC circuits from the standpoint of miniaturization and economic efficiency, especially in large-capacity uninterruptible power supplies.
Used by connecting many in parallel.

(Problem to be solved by the invention) However, as is well known, electrolytic capacitors utilize electrochemical reactions, and as the capacitance decreases and losses increase with time of use, the lifespan of electrolytic capacitors is limited depending on the usage conditions. is stipulated.

Therefore, in order to check the remaining life of an electrolytic capacitor and determine whether it is safe to replace it with a new one, we conduct periodic inspections, remove each capacitor one by one, and measure the capacitance of the capacitor.
We use a method to determine whether or not replacement is necessary based on the rate of decrease in capacity relative to the initial capacity.

This has the problem of not only requiring the equipment to be stopped for a long time, but also making inspection work difficult.

Also, since inspections are usually only carried out once a year,
In the worst case, if the life of the device reached its end, there was a risk that the device would fail and stop.

The present invention has been made in view of the above points, and an object of the present invention is to provide an uninterruptible power supply device that can diagnose the remaining life of an electrolytic capacitor in a DC circuit without stopping the device for a long time. .

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a power supply device that has a smoothing electrolytic capacitor in a DC circuit and supplies stabilized AC power, and another backup power supply, In an uninterruptible power supply that is configured with an uninterruptible switch that switches between the output of the power supply and a standby power source without momentary interruption, the uninterruptible switch switches to the standby power supply and the power supply only drains the residual charge of the electrolytic capacitor. A means for controlling the no-load operation as an input, and a signal corresponding to the discharge characteristic during the no-load operation is compared with a signal corresponding to the initial characteristic or the characteristic at the time of the previous inspection to diagnose the remaining life of the electrolytic capacitor. This means that there is a means to do so.

Also, in an uninterruptible power supply system, which is constructed by connecting multiple power supply units in parallel, each having a smoothing electrolytic capacitor in the DC circuit and supplying stabilized AC power.

A means for disconnecting one of the power supply devices from the parallel connection and controlling the disconnected power supply device to operate with no load using only the residual charge of the electrolytic capacitor as input, and a discharge characteristic of the electrolytic capacitor during this no-load operation. A means is provided for diagnosing the remaining life of the electrolytic capacitor by comparing the corresponding signal with the signal corresponding to the initial characteristic or the characteristic at the time of the previous inspection.

(effect) In an uninterruptible power supply with such a configuration.

Since the capacitance of an electrolytic capacitor decreases with usage time, the discharge characteristics of the electrolytic capacitor when the power supply is operated with no load using only the residual charge of the electrolytic capacitor as input determines how much the capacitance is from its initial value. The remaining life of the electrolytic capacitor is diagnosed by estimating whether the capacitance has decreased to %.

(Example) An embodiment of the present invention will be described below with reference to FIG.

In FIG. 1, the same parts as those in FIG. 4 are given the same reference numerals, and the explanation thereof will be omitted, and only the different points will be described here. That is, in FIG.

21 is a sequence control circuit that turns off the changeover switch 10 and turns on the changeover switch 11 to switch to power supply from the direct commercial power supply 1, stops the rectifier 3, and turns off the storage battery connection switch; 22 detects the discharge characteristics of the electrolytic capacitor 5; The voltage detector 23 is an electrolytic capacitor remaining life detector.

Next, the operation of the uninterruptible power supply configured as described above will be described. In normal operating conditions, the changeover switch 11 is off, the changeover switch 10 is on, and power is supplied by the inverter 8.

In order to determine the remaining life of the electrolytic capacitor 5, first, the sequence control circuit 21 turns on the changeover switch 11.
After turning off the changeover switch 10 and switching to power supply from the direct commercial power supply 1 without momentary interruption, the input switch is turned off to stop the rectifier 3 or the gate of the rectifier thyristor is turned off), and the storage battery connection switch is turned off (the commercial power supply 2, (Originally off when in good condition), and only the inverter 8 is operated with no load using the residual charge of the electrolytic capacitor 5 as input. The discharge characteristics of the electrolytic capacitor 5 at this time are detected by the voltage detector 22 and input to the remaining life detector.

The solid line waveform in FIG. 2 shows the discharge characteristics of the electrolytic capacitor 5 detected by the voltage detector 22. The broken line waveform corresponds to the initial discharge characteristics of the electrolytic capacitor 5 at the time of manufacture.

The voltage E of the electrolytic capacitor 5 at time t1 in FIG.
Letting the electrostatic capacitance of the electrolytic capacitor 5 be C, it is expressed by the following relational expression.

E = Eo (1eXP(ti/RC)) In other words, it is possible to estimate the capacitance C from the above relational expression, and the remaining life detector 23 calculates the capacitance C based on this m principle. Then, compare it with the capacitance C0 corresponding to the broken line waveform in Figure 2, calculate the decrease in capacitance,
Determine remaining life.

(For example, if the capacitance has decreased by about 30%, it is determined that the life span has been reached.) This makes it easy to determine whether or not replacement is necessary.

In this way, in this embodiment, the inverter 5 is operated with no load using the residual charge of the electrolytic capacitor 5 as input,
The remaining life of the electrolytic capacitor 5 is determined by estimating the capacitance of the electrolytic capacitor 5 from the discharge characteristics of the electrolytic capacitor 5 at that time and comparing it with the initial value of capacitance. Therefore, the capacitance can be easily determined without having to measure the capacitance of each individual piece.

Furthermore, with the configuration of this embodiment, instead of being limited to once a year like conventional periodic inspections, it is possible to check at any time or, for example, once a month. It is also possible to avoid the risk that the equipment will reach the end of its service life during the inspection period and the equipment will fail and stop.

In the embodiment shown in FIG. 1, the configuration may be such that the storage battery connection switch 7 is not provided. In this case, in order to disconnect the storage battery, it is sufficient to turn off the switch for the storage battery input. In the description of the embodiment, the calculated value of the capacitance C of the electrolytic capacitor 5 is compared with the initial capacitance value, but it may also be compared with a value from a past measurement.

Furthermore, the present invention can also be applied to an uninterruptible power supply device using a parallel system in which the outputs of the power supply devices shown in FIG. 1 are connected in parallel, and FIG. 3 shows an embodiment thereof. The figure is
This shows an example of application to a two-unit parallel system, where 32 is a switch for parallel connection/disconnection, and 31 is provided in place of 21 in FIG.

This is a sequence control circuit that turns off the switch to disconnect the parallel connection, stops the rectifier 3, and turns off the storage battery connection switch 7.

Furthermore, the configurations of the power supply unit w3^ of the first machine and the power supply unit 3B of the second machine are exactly the same.

For example, to determine the remaining life of the electrolytic capacitor 5 of the power supply device 3A of the first unit, the sequence control circuit 31 turns off the switch 32, the power is supplied only by the power supply unit 3B of the second unit, and then the rectifier 3 is stopped. , the storage battery connection switch is turned off, and the inverter 8 is operated with no load using the residual charge of the electrolytic capacitor 5 as input. The means for determining the remaining life of the electrolytic capacitor 5 is exactly the same as in the embodiment shown in FIG.

Further, in the embodiment shown in FIG. 3, a two-unit parallel system is used, but it goes without saying that the same effect can be obtained even if there are three or more units.

〔Effect of the invention〕

As described above, according to the present invention, the capacitance of the electrolytic capacitor is estimated from the discharge characteristics when the power supply is operated with no load using the residual charge of the electrolytic capacitor as input, and is compared with the initial value. Accordingly, it is possible to provide an uninterruptible power supply device having a means for diagnosing the remaining life of an electrolytic capacitor without stopping the power supply device for a long time.

[Brief Description of the Drawings] Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a characteristic diagram showing the discharge characteristics of an electrolytic capacitor due to no-load operation of the inverter in the embodiment of Fig. The figure is a block diagram showing another embodiment of the present invention, and FIG. 4 is a block diagram showing an example of the configuration of a conventional uninterruptible power supply. 1... Direct commercial power supply, 2... Commercial power supply, 3... Rectifier, 4... Smoothing reactor, 5... Electrolytic capacitor. 6-...Storage battery, 7...Storage battery connection switch. 8... Inverter, 9... AC filter, 10
．． 11... Selector switch, 12... Load, 21
... sequence control circuit, 22 ... voltage detector,
23... Remaining life detector, 31... Sequence control circuit, 32... Switch. Figure 1 Figure 3 Figure 2

Claims (2)

[Claims] (1) A power supply device that receives AC power or DC power as input, has a smoothing electrolytic capacitor in the DC circuit, and supplies stabilized AC power, another backup power source, and the output of the power supply device and the backup power source. In an uninterruptible power supply device configured with an uninterruptible switch that switches the power supply without instantaneous interruption, the uninterruptible switch switches the power supply from the standby power source, and at the same time, the power supply device is operated without interruption using only the residual charge of the electrolytic capacitor as input. A means for controlling the electrolytic capacitor to operate under load, and comparing a signal corresponding to the discharge characteristics of the electrolytic capacitor during no-load operation with a signal corresponding to the initial characteristic or the characteristic at the time of past inspection to determine the remaining life of the electrolytic capacitor. An uninterruptible power supply characterized by comprising means for diagnosing. (2) In an uninterruptible power supply device, which is constructed by connecting in parallel a plurality of power supply devices that input AC power or DC power, have a smoothing electrolytic capacitor in the DC circuit, and supply stabilized AC power, Means for disconnecting one of the units from the parallel connection and controlling the disconnected power supply unit to perform no-load operation using only the residual charge of the electrolytic capacitor as input, and corresponding to the discharge characteristics of the electrolytic capacitor during this no-load operation. 1. An uninterruptible power supply device comprising means for diagnosing the remaining life of the capacitor by comparing the signal corresponding to the initial characteristic or the characteristic at the time of past inspection.