JP2003299261A - Power storage device - Google Patents

Abstract

(57) [Problem] To provide a function as an emergency power supply to a power storage device which has been practically impossible to use as an emergency power supply without significantly increasing the cost. The power storage device includes a storage battery, means for detecting the presence or absence of electric power supplied from the external power supply to the storage battery, storage battery voltage detection means, and discharge interruption means for ending the discharge of the storage battery. While the power supplied from the battery is detected, the battery discharge is terminated when the battery voltage reaches the predetermined voltage V2, and while the power supplied from the external power supply is not detected, the battery voltage is determined in advance. A power storage device configured to terminate discharge of the storage battery when the voltage V1 (V1 <V2) is reached.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a power storage device. 2. Description of the Related Art As a typical method of using an electric power storage device, a storage battery is charged at midnight when the electricity rate is low, and discharged from the charged storage battery immediately before noon when demand for commercial power reaches a peak. So-called load leveling (load standardization) that suppresses the use of commercial power. In such a usage method, the storage battery used for the power storage device is different from the storage battery of the float use used for the emergency power supply which is discharged only in an emergency, and is different from the cycle use in which the battery is repeatedly charged and discharged during the use period. Become. [0003] In many cases, a storage battery using a cycle has a shorter life (useful life instead of the number of times of charge and discharge) than a storage battery using a float. This is due to a change in the form of the active material due to charge and discharge. In order to prevent such deterioration, it is necessary to avoid overcharging or overdischarging of the storage battery as much as possible, which adversely affects the life performance. [0004] As a method of avoiding the above overcharge and overdischarge,
Methods for preventing overcharge include calculation of the amount of electricity, detection of storage battery voltage, detection of charging time, and the like. Methods of preventing overdischarge are mainly based on detection of storage battery voltage, which is generally used. When the discharge lower limit voltage (V2) is reached, the discharge is forcibly terminated. However, actually, the discharge is not always performed up to the set discharge lower limit voltage (V2), and the discharge is often stopped at a higher voltage state. In addition, the set discharge lower limit voltage (V2)
In general, it is general to set a voltage in a state where a certain amount of capacity remains, instead of a voltage in a state where the capacity of the storage battery is almost exhausted. [0005] Generally, such power storage devices rarely have a function as an emergency power supply. The reason for this is that when used as a power storage device, the battery is mainly discharged at a current of 1 CA or less with respect to the rated capacity of the storage battery so that discharge can be performed for at least several hours. This is because the power supply for use only has to satisfy a discharge time of several minutes to several tens of minutes at the time of power failure, and is mainly discharged with a current larger than 1 CA with respect to the rated capacity of the storage battery. Especially when the storage battery used is a lead storage battery,
As the discharge current increases, the voltage drop immediately after the start of discharge increases. This example is shown in FIG. In this example, the voltage-time curve when the 6-cell monoblock battery is discharged at 3 CA and the voltage-time curve when discharged at 0.05 CA are 1
It is summarized in two graphs. As can be seen from this figure, in the power storage device, the above-described discharge lower limit set voltage (V2) is temporarily set to 11.11.
When the voltage is set to 4 V (1.9 V / cell), the discharge can be performed only for 1 to 2 minutes when the discharge is performed at 3 CA like an emergency power supply. In the power storage device, if the discharge lower limit setting voltage (V2) is lower than 1.9 V / cell,
In normal use, the discharge may be deep and the charge / discharge cycle life may be shortened. If it is higher than 1.9 V / cell, it becomes more unsuitable as an emergency power supply. For this reason, the power storage device cannot be practically used as an emergency power source. SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has been proposed for an electric power storage device which has been practically impossible to be used as an emergency power source. The function as a power supply is provided. The present invention has been made to solve the above-mentioned problems. According to the present invention, there is provided a storage battery, means for detecting the presence or absence of power supplied from an external power supply to the storage battery, storage battery voltage detection means, In a power storage device including a discharge interrupting unit that terminates discharge of a storage battery, the discharge of the storage battery is terminated when the storage battery voltage reaches a predetermined voltage V2 while power supplied from an external power supply is detected. A power storage device configured to terminate discharging of the storage battery when the storage battery voltage reaches a predetermined voltage V1 (V1 <V2) while power supplied from an external power supply is not detected. is there. Hereinafter, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention. The power storage device of the present invention, a storage battery such as a lead storage battery,
Means for detecting the presence or absence of power supplied from an external power supply such as a voltmeter or ammeter having an output terminal, storage battery voltage detecting means such as a voltmeter having an output terminal, and forcing discharge of a storage battery such as a relay This is provided with a discharge interrupting means that terminates the power supply, and is normally connected to a load while receiving power supply from an external power supply such as a commercial power supply or a generator. A means for detecting the presence or absence of power supplied from an external power supply of the power storage device (power detection means in FIG. 1) determines whether or not power is supplied from the external power supply to the power storage device. Means, and can be selected from detection means such as magnetic field detection in addition to the above-described voltage detection and current detection. If the power detection means determines that power is being supplied, the output lower limit voltage of the power storage device is changed to the normal discharge lower limit voltage V2 by a signal from its output terminal.
Is selected, but if it is determined that power is not being supplied due to a power failure, a generator failure, or the like, the discharge lower limit setting voltage is set to V1 lower than V2 by a signal from its output terminal. In the lead storage battery, V1 is 1.9 to 1.9.
It is preferable that 2.0 V / cell and V2 be set to about 1.6 to 1.7 V / cell. The storage battery of this power storage device is charged / discharged according to a load request or a set charging / discharging program, and its voltage is detected by storage battery voltage detecting means such as a voltmeter having an output terminal, and corresponds to the voltage. A signal is emitted. The storage battery voltage detection means activates the discharge cutoff means such as a relay by a signal generated by a voltmeter or the like having an output terminal when the storage battery voltage reaches the discharge lower limit set voltage (V2 or V1), and electrically connects the load and the power storage device. Cut. Note that the discharge interrupting means is not limited to a relay, and a logic circuit or the like can be used. Here, the storage battery is not limited to the above-mentioned lead storage battery, but may be a nickel cadmium battery, a nickel hydrogen battery,
Various secondary batteries such as lithium ion batteries can be selected. Their capacity, number, and combination method (series connection, parallel connection, combination of both) can be freely selected according to the design of the power storage device. It is possible. Further, the storage battery voltage detecting means may detect the voltage of the whole assembled battery, may detect the voltage of one or more storage batteries, and may detect and calculate the voltage of a plurality of storage batteries. The power storage device of the present invention does not require a significant system change as compared with the conventional power storage device, so that the manufacturing cost does not increase significantly. Further, when a lead storage battery is used in the power storage device of the present invention, when discharging with a large current in an emergency such as a power failure, the discharge lower limit setting voltage V1 can be set to a value that is about 1/2 of V2. Therefore, it is useful and suitable as an emergency power supply. According to the present invention, a power storage device, which has been practically impossible to use as an emergency power source,
The function as an emergency power supply is provided without significantly increasing the cost.

[Brief description of the drawings] FIG. 1 is a block diagram of the present invention. FIG. 2 Discharge curve of lead storage battery

Claims (1)

Claims: 1. A storage battery, comprising: means for detecting the presence or absence of power supplied from an external power supply to the storage battery; storage battery voltage detection means; and discharge interrupting means for ending discharge of the storage battery. In the power storage device, while the power supplied from the external power supply is detected, the discharge of the storage battery is terminated when the storage battery voltage reaches the predetermined voltage V2, and while the power supplied from the external power supply is not detected. A power storage device configured to stop discharging the storage battery when the storage battery voltage reaches a predetermined voltage V1 (V1 <V2).