JPH0888941A - Determining device of quality of storage battery for uninterruptible power supply unit - Google Patents

Abstract

PURPOSE: To continue the operation of an uninterruptible power supply unit even when a defective cell exists mixedly in a series storage battery for backup and to detect the defective cell without interrupting power supply to a load. CONSTITUTION: An alternating current IAC flowing through a series storage battery 6 during a floating charge is extracted through the intermediary of an alternating current detector 30 and a band-pass type filter 33, while an AC voltage VAC impressed on the series storage battery 6 is extracted through the intermediary of a series capacitor 31, an AC voltage detector 32 and a band-pass type filter 34, and an impedance computation circuit 35 determines an internal impedance by the computation of VAC÷IAC. An alarm is issued when the value of this impedance exceeds a prescribed value. In another way, the voltage of each cell constituting the series storage battery 6 is detected with the cells switched over and a discrete impedance computation circuit calculates the internal impedance of each cell. In still another way, the cells constituting the series storage battery 6 are divided into a plurality of cell groups and a group impedance computation circuit calculates the internal impedance of each cell group.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a storage battery quality determination device for an uninterruptible power supply, which can determine the quality of a storage battery constituting the uninterruptible power supply while operating the uninterruptible power supply. .

[0002]

2. Description of the Related Art Electronic devices such as computers operate continuously for 24 hours, and it is not allowed to stop the supply of electric power even for a short time. Therefore, power is supplied through the uninterruptible power supply. FIG. 4 is a circuit diagram showing a conventional example of an uninterruptible power supply. In the conventional circuit of FIG. 4, a charger as a first power converter 3, an inverter as a second power converter 4, a DC intermediate circuit 5, which connects the DC side of the charger 3 and the DC side of the inverter 4, Further, the series storage battery 6 connected to the DC intermediate circuit 5 constitutes an uninterruptible power supply device, and the uninterruptible power supply device is installed between the AC power supply 2 and the load 7 via the circuit breaker 8. The charger 3 supplies direct-current power to the inverter 4 and floatingly charges the series storage battery 6 so that the series storage battery 6 is always in a charging completed state. Therefore, even if the AC power supply 2 suddenly loses power due to an accident, etc., this series storage battery 6
Supplies DC power to the inverter 4 instead of the AC power source 2, so that the load 7 connected to the inverter 4
Can continue to operate without a power failure.

Since the DC intermediate circuit voltage of the uninterruptible power supply is generally 300V to 400V, the series storage battery 6 connected to the DC intermediate circuit 5 has a structure in which 150 to 200 cells are connected in series. If a cathode absorption lead-sealed storage battery is used as the series storage battery 6, it is frequently used because it can save the trouble of maintenance and inspection, but it has a characteristic that the internal resistance increases due to long-term use. If the internal resistance increases, the discharge capacity will be adversely affected. Therefore, even one of the cells in the series storage battery 6 may be abnormal (the defect in which the internal resistance increases as described above is the majority of the abnormality). If it occurs, the power cannot be supplied from the series storage battery 6 to the load 7 when the AC power supply 2 fails. Alternatively, the power supply ends in a short time. Therefore, the uninterruptible power supply device tries to detect a defective cell during operation while floating charging the series storage battery 6, but since the charging current during floating charging is small, the voltage of each cell during charging is small. Therefore, it is extremely difficult to detect the increase in internal resistance. If a large current is passed, a defective cell can be detected from the voltage of each cell, but in order to pass a large current, a load resistor commensurate with the storage battery capacity must be prepared, and the series storage battery 6 sends a current to this load resistor. If the AC power supply 2 fails during this time, there is the inconvenience that this power failure cannot be backed up.

However, if the series storage battery 6 constituting the uninterruptible power supply unit has a defect, not only the uninterruptible power supply unit cannot perform its function but also the blackout of the load 7 has a serious influence. It is necessary to be able to check the quality of the series storage battery 6 while continuing the operation of the device. Therefore, the conventional example circuit of FIG. 4 is provided with a circuit that can determine the quality of the series storage battery 6 while operating the uninterruptible power supply. That is, in response to the inspection command signal, the storage battery inspection command circuit 11 gives a cutoff signal to the circuit breaker 8 to turn it off, so that the series storage battery 6 supplies power to the load 7 via the inverter 4 instead of the AC power supply 2. To supply. The discharging current of the series storage battery 6 at this time is much larger than the charging current during floating charging. A voltage detector (not shown) is provided in the DC intermediate circuit 5.
, And monitors the voltage of the series storage battery 6, and when the value reaches the discharge end voltage, the circuit breaker 8 is turned on to return to the original state (that is, the state in which the AC power supply 2 supplies power). During the discharging period until then, the storage battery check command circuit 11 gives a switching command to the cell changeover switch 12 to detect the voltage of each cell constituting the series storage battery 6. The defective cell detection circuit 13 detects defective cells by comparing the cell voltages with each other and by comparing the cell voltages with a reference value.

[0005]

In the conventional circuit of FIG. 4, since the series storage battery 6 has a large discharge current, it is easy to detect a defective cell by checking the voltage of each cell. However, if there is a defective cell, the series storage battery 6 is in a state in which it cannot back up the power failure, so if the circuit breaker 8 is turned off in accordance with the command of the storage battery inspection command circuit 11, the load 6 will be in a power failure. There is. .

Therefore, an object of the present invention is to detect a defective cell without interrupting the load by continuing the operation of the uninterruptible power supply even if the series battery for backup contains defective cells. Is to

[0007]

In order to achieve the above-mentioned object, a quality determining device for a storage battery for an uninterruptible power supply according to the present invention is a first power for converting AC power into DC power and outputting the DC power to a DC intermediate circuit. In the uninterruptible power supply device including a converter, a second power converter connected to the DC intermediate circuit to convert DC power into AC power, and a storage battery connected to the DC intermediate circuit, the power flows to the storage battery. An alternating current detection circuit that detects an alternating current component of a charging current, an alternating voltage detection circuit that detects an alternating voltage component of a charging voltage applied to the storage battery, and an ac current detection value and an alternating voltage detection value of the storage battery An impedance calculation circuit for calculating internal impedance and a pass / fail judgment circuit for issuing an alarm when the calculated internal impedance value exceeds a set value are provided.

Alternatively, a first power converter that converts AC power into DC power and outputs the DC power to a DC intermediate circuit, and a second power converter that is connected to the DC intermediate circuit and converts DC power into AC power. In an uninterruptible power supply having a configuration in which a series storage battery composed of a plurality of cells connected in series is connected to the DC intermediate circuit, an AC current detection circuit that detects an AC current component of a charging current flowing to the series storage battery, and the series storage battery. An individual AC voltage detection circuit that detects the AC voltage component of the applied charging voltage for each individual cell, and an individual impedance calculation circuit that calculates the internal impedance of each cell from these AC current detection values and individual AC voltage detection values. And a pass / fail judgment circuit that issues an alarm when the calculated individual internal impedance value exceeds a set value.

Alternatively, an alternating current detection circuit for detecting an alternating current component of a charging current flowing to the series storage battery, and the series storage battery are divided into a plurality of cell groups, and an alternating voltage component of a charging voltage applied to the series storage battery. A group AC voltage detection circuit for detecting each cell group, a group impedance calculation circuit for calculating the internal impedance of each cell group from the AC current detection value and the group AC voltage detection value, and the group internal impedance calculation value is And a pass / fail judgment circuit for issuing an alarm when the set value is exceeded.

[0010]

When the series storage battery 6 connected to the DC intermediate circuit 5 of the uninterruptible power supply is floating-charged, the charger 3
Due to the influence of the input current of 1 or the output current of the inverter 4, a small amount of AC current flows through the series storage battery 6 and an AC voltage is applied.

FIG. 5 is a model circuit diagram showing the DC circuit portion of the uninterruptible power supply as a model.
The series storage battery 6 is connected to a series circuit of the AC power supply 22 and the AC power supply 22. Therefore, attention is paid to the fact that a current in which the alternating current I _AC is superimposed on the direct current I _DC flows to the series storage battery 6, and the alternating current I _AC flowing to the series storage battery 6 and the alternating voltage V _AC applied thereto. From the above, the internal impedance of the series storage battery 6 or the individual impedance of each cell forming the series storage battery 6 or the cells forming the series storage battery 6 is divided into a plurality of cell groups, and the group impedance of each cell group is calculated. The quality is judged from this calculated value.

[0012]

FIG. 1 is a model circuit diagram showing a first embodiment of the present invention, in which a DC circuit portion of an uninterruptible power supply is modeled, and a series storage battery 6, a DC power supply 21, and Since the name, application, and function of the AC power supply 22 have been described in FIG. 5, their description will be omitted.

In the first embodiment circuit of FIG. 1, the series storage battery 6
An alternating current I _AC flowing to the impedance detection circuit 35 is detected by the alternating current detector 30 and the filter 33 and sent to the impedance calculation circuit 35.
It is a band-pass filter that extracts the most existing frequency components. On the other hand, when the series connection circuit of the series capacitor 31 and the AC voltage detector 32 and the primary side of the AC voltage detector 32 are connected in series and connected between the positive and negative electrodes of the series storage battery 6, the AC voltage detector 32 Since the high-pass transmission type filter is constituted by the exciting inductance of the above and the capacitance of the series capacitor 31, the DC voltage component is applied to the series capacitor 31, so that the AC voltage component is present on the secondary side of the AC voltage detector 32. Only appears. Therefore, the AC voltage V detected through the filter 34, which is a bandpass filter.
_AC is sent to the impedance calculation circuit 35.

The impedance calculation circuit 35 uses an AC voltage V
_The internal impedance is calculated by dividing _AC by the AC current I _AC , and when this value exceeds a predetermined value, the quality determination circuit 36 issues an alarm. FIG. 2 is a model circuit diagram showing a second embodiment of the present invention. The series storage battery 6, the DC power supply 21, the AC power supply 22, the AC current detector 30, the series capacitor 31 shown in the second embodiment circuit are shown. The names, applications, and functions of the AC voltage detector 32, the filter 33, the filter 34, the impedance calculation circuit 35, and the pass / fail judgment circuit 36 are the same as those in the first embodiment circuit described above with reference to FIG. Is omitted. The series capacitor 31 and the AC voltage detector 32 are shown as a single line, but their connections are the same as in the first embodiment circuit of FIG.

The circuit of the second embodiment is provided with a cell changeover switch 41 so that the AC voltage V _AC of each cell constituting the series storage battery 6 can be individually detected, and instead of the impedance calculation circuit 35. 1 is different from the circuit of the first embodiment described above in FIG. 1 in that the individual impedance calculation circuit 42 is used.
The description of the circuit of the second embodiment is omitted.

FIG. 3 is a model circuit diagram showing a third embodiment of the present invention. The series storage battery 6, DC power source 21, AC power source 22, AC current detector 3 shown in the third embodiment circuit are shown.
0, series capacitor 31, AC voltage detector 32, filter 33, filter 34, impedance calculation circuit 35,
The names, uses, and functions of the pass / fail judgment circuit 36 are the same as those in the case of the circuit of the first embodiment described above with reference to FIG. The series capacitor 31 and the AC voltage detector 32 are shown as a single line, but their connections are the same as in the first embodiment circuit of FIG.

In the circuit of the third embodiment, each cell constituting the series storage battery 6 is divided into a plurality of cell groups, and the cell group changeover switch 51 is provided so that the AC voltage V _AC of each cell group can be detected separately. 1 and the point that a group impedance calculation circuit 52 is provided instead of the impedance calculation circuit 35, which is the same as the circuit of the first embodiment described above with reference to FIG. Therefore, the description of the third embodiment circuit will be omitted.

[0018]

According to the present invention, an AC current component and an AC voltage component flowing through the storage battery for an uninterruptible power supply during floating charging are taken out through an appropriate filter and the AC voltage is divided by the AC current. By doing so, the internal impedance of the storage battery is calculated, and if this calculated value exceeds a predetermined value, it is determined that the storage battery is defective. With such a configuration, it is possible to determine the quality of the storage battery even when the uninterruptible power supply is in operation, and thus it is possible to reliably detect a defect in the storage battery without power failure of the load. Even in the case of a series storage battery in which a large number of cells are connected in series, the quality of each cell can be sequentially determined while floating charging, so that defective cells can be detected without being restricted by time.

[Brief description of drawings]

FIG. 1 is a model circuit diagram showing a first embodiment of the present invention.

FIG. 2 is a model circuit diagram showing a second embodiment of the present invention.

FIG. 3 is a model circuit diagram showing a third embodiment of the present invention.

FIG. 4 is a circuit diagram showing a conventional example of an uninterruptible power supply.

FIG. 5 is a model circuit diagram in which a DC circuit portion of the uninterruptible power supply is modeled and represented.

[Explanation of symbols]

 2, 22 AC power supply 3 Charger as first power converter 4 Inverter as second power converter 5 DC intermediate circuit 6 Series storage battery 7 Load 8 Circuit breaker 11 Storage battery inspection command circuit 12 Cell changeover switch 13 Defective cell detection circuit 21 DC power supply 30 AC current detector 31 Series capacitor 32 AC voltage detector 33, 34 Filter 35 Impedance calculation circuit 36 Good / bad judgment circuit 41 Cell changeover switch 42 Individual impedance calculation circuit 51 Cell group changeover switch 52 Group impedance calculation circuit

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location H02J 9/02 B

Claims (3)

[Claims] 1. A first power converter that converts AC power into DC power and outputs the DC power to a DC intermediate circuit, and a second power converter that is connected to the DC intermediate circuit and converts DC power into AC power. In an uninterruptible power supply device comprising a storage battery connected to the DC intermediate circuit, an AC current detection circuit for detecting an AC current component of a charging current flowing to the storage battery, and an AC voltage component of a charging voltage applied to the storage battery. An AC voltage detection circuit for detecting, an impedance calculation circuit for calculating the internal impedance of the storage battery from the AC current detection value and the AC voltage detection value,
A pass / fail determination device for a storage battery for an uninterruptible power supply, comprising: a pass / fail determination circuit that issues an alarm when the calculated internal impedance value exceeds a set value. 2. A first power converter that converts AC power into DC power and outputs the DC power to a DC intermediate circuit, and a second power converter that is connected to the DC intermediate circuit and converts DC power into AC power. In an uninterruptible power supply having a configuration in which a series storage battery composed of a series connection of a plurality of cells is connected to the DC intermediate circuit, an AC current detection circuit for detecting an AC current component of a charging current flowing to the series storage battery, and the series storage battery. An individual AC voltage detection circuit that detects the AC voltage component of the applied charging voltage for each individual cell, and an individual impedance calculation circuit that calculates the internal impedance of each cell from these AC current detection values and individual AC voltage detection values. A storage battery for an uninterruptible power supply, comprising: a pass / fail judgment circuit that issues an alarm when the calculated individual internal impedance value exceeds a set value. Pass / fail judgment device. 3. A first power converter that converts AC power into DC power and outputs the DC power to a DC intermediate circuit, and a second power converter that is connected to the DC intermediate circuit and converts DC power into AC power. In an uninterruptible power supply having a configuration in which a series storage battery composed of a plurality of cells connected in series is connected to the DC intermediate circuit, an AC current detection circuit that detects an AC current component of a charging current flowing to the series storage battery, and the series storage battery. A group AC voltage detection circuit that divides into a plurality of cell groups and detects the AC voltage component of the charging voltage applied to the series storage battery for each cell group, and the AC current detection value and the group AC voltage detection value from each of the above. A group impedance calculation circuit for calculating the internal impedance of the cell group and a pass / fail judgment circuit for issuing an alarm when the calculated value of the group internal impedance exceeds a set value. A storage battery quality judgment device for an uninterruptible power supply.