JPS635410Y2 - - Google Patents

Description

[Detailed explanation of the idea]

The present invention relates to a battery used for power peak cut, load level or surplus power absorption, and its control management device. When using batteries for such purposes, the simplest method is to directly connect a battery group consisting of the required number of single cells connected in series to a DC bus bar. However, the voltage of a battery changes greatly when it is charged and discharged. For example, in a lead battery, 2.1V when charging/2.0~ when discharging the cell
The voltage is 1.5V/cell, so if you just connect it directly like this, if you choose a number of cells that are easy to discharge, you will likely be undercharged, and if you choose a number of cells that are easy to charge, you will end up overcharging. Therefore, as shown in the principle diagram of FIG. 1, the battery 2 and the bus bar 3 are connected via the charge/discharge control device 1, and the demand on the bus bar and the state of the battery are detected to control the flow of electricity into and out of the battery. is normal. To discharge the battery, press the discharge switch 6.
is turned on, and the charging switch 7 is turned off, and the battery is connected to the bus bar via the discharge booster 4. Note that the discharge booster 4 may be replaced by a simple connection bar. When charging the battery, turn on the charging switch 7.
When the ON discharge switch 6 is turned OFF, the voltage of the charging booster 5 is added to the bus voltage and applied to the battery. A simple connection line may be used instead of the charging booster 5. Combinations of how to abbreviate these boosters are shown in the table below.

Whether to use the combination with [Table] should be determined depending on the specific conditions of use, but in principle they are all the same. In other words, when the battery needs to be discharged, the voltage of the series connection between the battery and the booster (or connection line) is increased, and when the battery needs to be charged, the voltage of the series connection between the battery and the booster (or connection line) is decreased. It is to operate as follows. FIG. 2 shows this situation using an example. The straight line ABB'C' in FIG. 2 is the current-voltage characteristic at point Q in FIG. In other words, the straight line AB is the charging characteristic of the battery group, and the straight line B'C' is the discharging characteristic of the battery group. If the load becomes large and it becomes necessary to discharge the battery, the battery and discharge booster will be connected by the above switch operation, and the current-voltage characteristic at point P in Figure 1 will change to the characteristic shown by the broken line B''C'' in Figure 2. A discharge occurs.
On the other hand, in the case of charging by regeneration from the load, the battery is connected to the DC bus by the above operation (switch 6 OFF, switch 7 ON), so the characteristics of point P in Figure 1 are the same as those of point Q, and the characteristics of point P in Figure 2 are the same as those of point Q in Figure 2. It becomes straight line AB. Furthermore, even if there is no regeneration, if the bus voltage is high, the battery is charged using the same control.
When the load increases, the bus voltage decreases, and when regenerative power is generated, the bus voltage increases, so the above control can be performed by detecting the bus voltage and charging if it is higher than a certain set value, and discharging if it is lower. Changing this setting value changes the balance of charging and discharging the battery. The situation will be explained using FIG. 2. If the set value is selected as a relatively high value, B'' in Figure 2, the battery's discharge characteristics will be B''C'' and its charging characteristics will be AD, allowing the battery to be discharged until the bus voltage becomes relatively high and the discharge current reaches 0. On the other hand, charging occurs only in the large current portion where the voltage is higher than B'', so there are fewer opportunities to be charged. Therefore, in such a case, the battery will cancel out the charging and discharging, and when considered as a whole, the battery will discharge in the direction of progress. On the other hand, if the set voltage is set to a relatively low value B in Figure 2, the discharge characteristics will be EC'' and the charging characteristics will be
With AB, contrary to the above, the range where it can be discharged is narrowed and the range where it can be charged is widened, so charging progresses. Therefore, the discharge state of the battery is detected, and if the depth of discharge is shallow, the above set voltage is increased.For example, for lead batteries, the set voltage is increased.
2.15V/cell; the deeper the depth of discharge, the lower the set voltage; for example, 2.05V/cell for a lead-acid battery. To determine whether the depth of discharge is deep or shallow, the discharge amount determined by integrating the discharge current or the specific gravity of the electrolyte detected by an appropriate method, or the discharge amount determined in accordance with other factors, is determined by setting the discharge amount to a certain set value, for example, 60% discharge. This can be done by comparing the amount. It is common to have hysteresis characteristics in switching between discharging and charging by voltage detection and in switching the voltage setting value by detecting the battery discharge state. If the lower limit of the hysteresis of the high voltage setting value and the upper limit of the hysteresis of the low voltage setting value are selected to be equal, the following operation can be achieved.
In other words, if the discharge state of the battery is at the end of a certain set level, it will always operate to discharge the battery, and when the bus voltage exceeds the high level (i.e., the upper limit of the high set voltage hysteresis), it will switch to the operation to charge the battery. Then, when the bus voltage falls to the intermediate voltage, that is, the lower limit of the high set voltage hysteresis, that is, the upper limit of the low set level hysteresis, the operation returns to discharging the battery, and this state is maintained until the next detected voltage rise, and then the discharge continues. When the condition deepens and exceeds the rising set level, the battery is always charged, and when the detected voltage becomes low level, i.e., lower than the low set voltage or lower limit of hysteresis, the battery is discharged. When the voltage rises to the intermediate voltage, it returns to charging the battery, and then waits for a change in the bus voltage or battery discharge state. This operation allows the battery to be maintained at a depth of discharge within the target range. FIG. 3 shows an outline of an example of the device of the present invention having the above-mentioned functions. In the state shown in the figure, the battery 2, current detection shunt 16 and booster rectifier 5' are connected to the bus bar 3 via the magnet switch 6' which is always on, and the battery is discharging. This is because the voltage V _B detected from the bus is lower than the voltage V _S obtained by dividing the output of the reference voltage generator 9 by the resistors 91 and 92, so no output is output from the comparator 8 and the magnetic switch drive unit 15 does not work. state. When the bus voltage rises and becomes V _B > V _S , an output is generated from the comparator 8, and the magnetic switch drive operates to turn off contact 6' and turn on contact 7', causing battery 2 to switch between shunt 16 and contact 7'. Connects to the battery only through. In other words, the battery becomes charged. After that, when the voltage drops, the operation is reversed and the original state is restored. In order to avoid unnecessary switch operations and ensure stable switching when the bus voltage changes slightly, magnets are used to provide hysteresis characteristics so that the set voltage changes when switching from discharging to charging and vice versa. A contact 80 and resistors 81, 82, 83 operated by the switch drive unit 15 are used. In the above operation, the ratio by which the output of the reference voltage generator 9 is divided is changed using the contact 14 depending on the battery discharge depth. The state shown in FIG. 3 is a state where the depth of discharge is shallow. That is, the voltage generated by the discharge flow in the shunt 16 is integrated by the integrator 10, and its output P _d , which is proportional to the integrated value, and the output P _S of the reference voltage generator 11 are input to the comparator 12 and compared. Since P _d <P _S , the contact 14 remains closed. Therefore, the voltage of the reference voltage generator becomes V _S as it is, and the voltage setting value becomes higher, so that the discharge progresses as explained above. Now, when the depth of discharge becomes deeper and P _d > P _S ,
The output of the comparator 12 is the magnetic switch drive unit 1.
3 and opens the contact 14, the value obtained by dividing the output of the reference voltage generator 9 by the resistors 91 and 92 becomes V _S , and the voltage setting value decreases, so that charging progresses as described above. Note that the integrator 10 is a reversible integrator that can perform integration by canceling out discharge and charge. It goes without saying that magnetic switches can be made contactless by using thyristors, transistors, etc. Although detailed explanations of the booster rectifier, comparator, reference voltage generator, integrator, etc. are omitted, commonly known ones can be used.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the principle of a storage battery device for load leveling, FIG. 2 is an example of an explanatory diagram of the operation of the storage battery device for load leveling, and FIG. 3 is an example of the storage battery device of the present invention. DESCRIPTION OF SYMBOLS 1... Charge/discharge control device, 2... Battery, 3... DC bus, 4... Booster for discharging, 5... Booster for charging, 5'... Booster rectifier, 6, 6', 7,
7'...Switch, 9...Reference voltage generator, 10
... Reversible integrator, 8 ... Comparator, 11 ... Reference voltage generator, 12 ... Comparator, 13, 15 ... Magnetic switch drive section, 14 ... Contact, 16 ...
...Shyanto.

Claims (1)

[Scope of utility model registration request] In a storage battery device that performs power peak cutting, load leveling, etc. by connecting a battery to the bus bar via a charging/discharging control device consisting of a discharge or charging booster, a changeover switch, etc., means for detecting the voltage of the bus bar; Means for detecting the discharge state of the battery, and controlling the charging and discharging of the battery so that the detected bus voltage is charged above a certain set voltage level and discharged below the set voltage level, and a charging/discharging switching operation. means for providing a hysteresis characteristic so that the set voltage level itself changes in conjunction with the change, so that the set voltage level for switching from discharging to charging is higher than the set voltage level for switching from charging to discharging; , Furthermore, the set voltage of the bus voltage is set such that when the discharge state of the battery is above a certain set level, the battery is charged, and when it is below the set level, the battery is discharged. A storage battery device comprising means for changing the level.