JP4654262B2 - DC power supply system and charging method thereof - Google Patents

Description

  The present invention relates to a DC power supply system and a charging method thereof.

  Generally, in a DC power supply system that supplies power to a DC load device, a rectifier that receives commercial AC power and outputs DC power such as DC 48V is used. Further, in order to continue power supply to the load device even when the commercial power is interrupted, the output of the rectifier is provided with a storage battery and a charger for charging the storage battery to provide a backup power supply system. When a storage battery is applied to a DC power supply system, an assembled battery in which one or more storage batteries called single cells are connected in parallel is used.

Patent Documents 1 and 2 below describe a battery system that supplies power output from a plurality of assembled batteries to a load via a discharger. Patent Document 1 describes a battery system and a converter in the discharger. Are described as being electrically connected to each other by a common conductor, and Patent Document 2 describes that each operation of the discharger is performed based on the same operation signal transmitted by the control unit. ing.
JP 2007-143266 A JP 2007-143291 A

  FIG. 5 shows a DC power supply system in which a rectifier, a storage battery, a charger and a discharger are combined. In the figure, the AC power of the commercial power source 1 is supplied to the rectifier 2, and the rectifier 2 converts the AC power into predetermined DC power and supplies it to the load 3. The assembled battery 4 is an assembled battery formed by combining a plurality of storage batteries, and six sets thereof are mounted. Each assembled battery 4 is charged via the charger 5 when the commercial power source 1 is active, and discharges to the load 3 via the discharger 7 when the commercial power source 1 is powered off.

  Each charger 5 performs so-called intermittent charging, which starts charging the assembled battery 4 when the remaining capacity of the connected assembled battery 4 decreases, and stops charging the assembled battery 4 when full capacity is reached. ing. The remaining capacity of the assembled battery 4 is reduced not only by discharge due to a power failure of the commercial power supply 1 but also by self-discharge of the storage battery itself. Here, when the remaining capacity of the assembled battery 4 is reduced by 10% with respect to the fully charged state, charging up to full charging (complementary charging) is started by the charger 5 connected to the assembled battery 4 And

  Here, there are cases where the remaining capacity of the six battery packs 4 decreases to 90% at the same time. In this case, since the total remaining capacity is also reduced to 90%, it is necessary to install an extra storage battery to compensate for this reduction, resulting in an increase in cost and installation space. Further, in order to avoid a decrease in remaining capacity up to 90%, for example, when charging is started when there is a decrease in remaining capacity up to 95%, the deterioration of the storage battery is promoted by increasing the charging frequency. Problems arise.

  As described above, in a storage battery system composed of a plurality of assembled batteries, if the remaining capacity of all the assembled batteries decreases at the same time, the total remaining capacity decreases, so it is necessary to install an extra storage battery and cost There is a problem that the installation space increases, and there is a problem that deterioration of the storage battery is promoted if the charging frequency is increased in order to avoid this problem.

  The above problem is a problem that occurs not only in a DC power supply system but also in a system having a storage battery in which a plurality of storage batteries are connected in parallel.

  In the present invention, when the remaining capacity of all the assembled batteries is reduced at the same time, the total remaining capacity is lowered, so that it is necessary to mount an extra storage battery, and the cost and installation space are increased. The problem to be solved by the present invention is to prevent deterioration of the storage battery while preventing a decrease in the total remaining capacity. It is providing the direct-current power supply system which suppresses, and its charging method.

In order to solve the above problem, in the present invention, as described in claim 1,
In a DC power supply system including a plurality of assembled batteries, a charger, and a charge control means for controlling a charging schedule of the charger, the number of assembled batteries is n, and the auxiliary charging unit time is T. The supplementary charging repetition ordinal number is an integer m of 0 or more, and the remaining capacity reduction rate from the full charge of the assembled battery when the supplementary charging of each assembled battery is started is c [%]. When the ratio of the required minimum remaining capacity to the fully charged capacity is Q _min [%], n, Q _min and c are Q _min ≦ 100% − (c / 2) (1 + 1 / n)
A DC power supply system characterized in that, when k is a natural number from 1 to n, supplementary charging of the kth assembled battery is started at time (k / n + m) T. Constitute.

In the present invention, as described in claim 2,
In a charging method of a DC power supply system comprising a plurality of assembled batteries, a charger, and a charging control means for controlling a charging schedule of the charger, the number of assembled batteries is n, and a supplementary charging unit time , T, the supplementary charging ordinal number being an integer m of 0 or more, and the remaining capacity decrease rate from the full charge of each assembled battery when the supplementary charging of each assembled battery is started, and c [%] When the ratio of the required minimum remaining capacity to the full charge capacity of the entire battery is Q _min [%], n, Q _min and c are Q _min ≦ 100% − (c / 2) (1 + 1 / n)
The charging of the DC power supply system is characterized in that at time (k / n + m) T, supplementary charging of the k-th assembled battery is started when k is a natural number from 1 to n. Configure the method.

In the present invention, as described in claim 3,
2. The DC power supply system according to claim 1, further comprising a rectifier that converts AC power into DC power, wherein each of the assembled batteries is connected in parallel via a diode that passes power only in a discharge direction of the assembled battery, and A DC power supply system is configured, which is connected in parallel to a power supply line from a rectifier to a load, and a maximum value of a charging voltage to the assembled battery is set to be equal to or lower than an output voltage of the rectifier.

In the present invention, as described in claim 4,
2. The DC power supply system according to claim 1, further comprising a rectifier that converts AC power into DC power, wherein each of the assembled batteries is connected in parallel via a discharger, and further connected in parallel to a power supply line from the rectifier to a load. The output voltage of the discharger is set to be equal to or lower than the output voltage of the rectifier to constitute a DC power supply system.

  According to the DC power supply system and the charging method of the present invention, the following effects can be obtained.

  The reduction of the total remaining capacity of the system can be reduced, and the number of extra storage batteries can be reduced, so that it is possible to save cost and space, and the charging frequency does not increase in individual assembled batteries. Deterioration of is suppressed.

In the direct-current power supply system according to the present invention, a plurality of sets of assembled batteries formed by connecting one or more storage batteries, a charger, and a charging control means for controlling a charging schedule of the charger are provided.
The number of assembled battery sets is n, the auxiliary charging unit time is T, the auxiliary charging ordinal number is an integer m of 0 or more, and from the full charging of the assembled battery when the auxiliary charging of each assembled battery is started When the remaining capacity decrease rate is c [%], and the ratio of the required minimum remaining capacity to the fully charged capacity of the entire assembled battery is Q _min [%],
n, Q _min and c are

を満たすよう定められ、ｋを１からｎまでの自然数とするとき、時刻（ｋ/ｎ＋ｍ）Ｔにおいて、ｋ番目の前記組電池の補充電が開始される。

When k is a natural number from 1 to n, supplementary charging of the k-th assembled battery is started at time (k / n + m) T.

  Hereinafter, embodiments of the present invention will be described by taking a DC backup power supply system using a nickel-metal hydride storage battery as an example, but the present invention is not limited to this.

<Embodiment 1>
FIG. 1 is a diagram for explaining an embodiment of the present invention. In the figure, AC power from a commercial power source 1 is supplied to a rectifier 2, and the rectifier 2 converts AC power into predetermined DC power, outputs 56 V, and supplies it to a load 3. The assembled battery 4 is an assembled battery (rated voltage 40.8 V, rated capacity 100 Ah) in which 34 nickel-metal hydride storage battery cells (rated voltage 1.2 V, rated capacity 100 Ah) are connected in series. System) is mounted (n = 2).

  Each assembled battery 4 is charged via a charger 5 when the commercial power source 1 is active. The operation of each charger 5 is controlled by the charge control means 8. Since the output voltage of the charger 5 is 54.4V, which is lower than the output voltage (56V) of the rectifier 2, when the commercial power source 1 is valid, the output of the rectifier 2 is supplied to the load 3, and the rectifier 2 1 is stopped due to a power failure or the like, the power output from the assembled battery 4 is supplied to the load 3 via the diode 6.

  Each charger 5 charges the connected assembled battery 4, but since each assembled battery 4 is connected in parallel via a diode 6, the charging current does not flow to other assembled batteries 4, and Since the full charge voltage of the assembled battery 4 is 54.4 V (1.6 V per cell) at the maximum, it can be charged to full charge. The assembled battery 4 is charged to the full charge by the charger 5 and the charging current becomes zero.

  Thereafter, even if the rectifier 2 continues to supply power to the load 3 without stopping, and the assembled battery 4 does not discharge to the load 3, the remaining capacity of the assembled battery 4 gradually decreases due to self-discharge. The self-discharge amount is 10% (rated capacity ratio) in 30 days.

  Therefore, it is necessary to charge the assembled battery 4 in accordance with the decrease in the remaining capacity, and the remaining capacity decrease from the full charge in which one assembled battery 4 needs to be charged is 10% (rated capacity ratio). When the remaining capacity is reduced, charging by the charger 5 (complementary charging) may be performed.

  However, when two sets of assembled batteries 4 independently determine that the remaining capacity is reduced by 10% from full charge and perform supplementary charging, both remaining capacities are reduced by 10% at the same time (the two sets of assembled batteries 4). The remaining capacity may also be reduced by 10%. Therefore, the time for the 10% remaining capacity to decrease after full charge is 30 days, and two sets of assembled batteries 4 are alternately supplemented every 15 days. That is, after one set of assembled batteries 4 is supplementarily charged at a certain time, the remaining one set is supplemented after 15 days, and then each assembled battery 4 is supplemented every 30 days. The minimum value of the remaining capacity is (95% + 90%) / 2 = 92.5% as shown in FIG. 2, and the total capacity reduction can be reduced.

  Regarding supplementary charging, the time required for one supplementary charging is negligibly short with respect to the repetition period of supplementary charging (complementary charging unit time T). "Is used without distinction.

  In the system (FIG. 3) in which three sets of the same assembled battery 4 are connected to the system of two sets of assembled batteries 4 described so far (FIG. 1) (FIG. 3), the first (1 System), the second (second system) assembled battery 4 is supplemented 10 days later, and the third (third system) assembled battery 4 is further supplemented 10 days later. After performing, supplementary charging of each assembled battery 4 is performed in a cycle of 30 days. At this time, the minimum value of the ratio of the total remaining capacity to the total capacity at full charge is (96.6% + 93.3% + 90%) / 3 = 93.3%.

In a system with n battery packs 4 set, the k-th set is 30 × k ÷ n days (k = 1, 2,..., N, k are numbers assigned to the battery pack 4) starting from a certain point in time. The auxiliary charging of the battery 4 is performed, and then the auxiliary charging of each assembled battery 4 is performed at a cycle of 30 days. At this time, the minimum value Q _min [%] of the ratio of the total remaining capacity to the total capacity at full charge is obtained as follows.

組電池４全体の、満充電時容量に対する所要最低残容量の割合（以下、所要最小割合と呼ぶ）を、同じく、Ｑ_ｍｉｎ［％］で表すとき、逆に、下記の式（３）を用いることで、所要最小割合Ｑ_ｍｉｎが先に決まっている場合に、組電池４の組数を決定することが可能である。

Similarly, when the ratio of the required minimum remaining capacity to the fully charged capacity (hereinafter referred to as the required minimum ratio) of the entire assembled battery 4 is expressed by Q _min [%], the following formula (3) is used. Thus, when the required minimum ratio Q _min is determined in advance, the number of assembled batteries 4 can be determined.

例えば、所要最小割合Ｑ_ｍｉｎが９４％とされた場合、式（３）よりｎ≧５と求められるから、組電池４の組数を５とし、６日毎に順番に組電池４を補充電していくようにすればよい。

For example, when the required minimum ratio Q _min is 94%, n ≧ 5 is obtained from Equation (3). Therefore, the number of the assembled batteries 4 is set to 5, and the assembled batteries 4 are supplemented in order every six days. You should make it go.

Further, when the required minimum ratio _Qmin is 93%, n ≧ 2.5 is obtained from Equation (3). Therefore, the number of assembled batteries 4 is set to 3, and the assembled batteries 4 are supplemented in order every 10 days. You should make it charge.

That is, the number n of the assembled batteries 4 and the required minimum ratio Q _min of the total remaining capacity satisfy Expression (3), and start from a certain point in time 30 × k ÷ n days (k = 1, 2,... n) supplementary charging of the k-th assembled battery 4 and then supplementarily charging each assembled battery 4 in a cycle of 30 days, so that the ratio of the total remaining capacity to the total capacity at full charge is the required minimum ratio so as not to fall below the Q _min, and it is possible to suppress the auxiliary charge frequency.

In Equation (3), no matter how large n is, since Q _min ≦ 95%, the required minimum ratio Q _min cannot be set exceeding 95%.

Next, the rate of capacity decrease from full charge that is required to perform supplementary charging (set to 10% in the above description) for one set of assembled batteries 4 is set to c [%] (that is, one set of battery packs 4). The rate of remaining capacity reduction from full charge of the assembled battery 4 when supplementary charging of the assembled battery 4 is started is defined as c [%]), and the relationship between n and the required minimum ratio Q _min is as follows: expressed.

電源システムの設計に際して、式（４）を用いて合計残容量の所要最小割合Ｑ_ｍｉｎと組電池４の組数ｎと補充電を行う容量低下割合ｃ［％］とを互いに調整することで、合計残容量の、満充電時合計容量に対する割合が所要最小割合Ｑ_ｍｉｎを下回らないようにすることができる。

When designing the power supply system, the required minimum ratio Q _min of the total remaining capacity, the number n of the assembled batteries 4 and the capacity reduction ratio c [%] for performing supplementary charging are mutually adjusted using Equation (4). it can be the total remaining capacity, the ratio for the full charge when the total volume so as not to fall below the required minimum ratio Q _min.

For example, when the required minimum ratio Q _min of the total remaining capacity is determined to be 95% and the number n of the assembled batteries 4 is determined to be 18, the capacity decrease ratio c for performing supplementary charging is 9.47% or less from the equation (4). Therefore, supplementary charging is performed by setting c to 9%. At this time, the number of days in which the remaining capacity decreases by 9% (c) from the full charge is 27 days, and 18 battery packs 4 are supplementarily charged in turn every 1.5 days (27 days ÷ 18 battery packs). The ratio of capacity to the total capacity at full charge is reduced to a minimum of 95.25%.

Thus, the number n of the assembled batteries 4 and the required minimum ratio Q _min of the total remaining capacity satisfy the formula (4), and the remaining capacity is reduced by c [%] from the full charge of the one assembled battery 4. Is T (auxiliary charging unit time), the auxiliary charging of the k-th assembled battery is performed at time T × k ÷ n (k = 1, 2,..., N) starting from a certain time point, and then each assembled battery 4 the by auxiliary charge with a period T, then the total remaining capacity ratio full charge when the total capacity so as not to fall below the required minimum rate Q _min, and it is possible to suppress the auxiliary charge frequency.

  In the present embodiment, the maximum value of the charging voltage to the assembled battery 4 is set to be equal to or lower than the output voltage of the rectifier 2.

<Embodiment 2>
FIG. 5 is also used to describe the embodiment of the present invention. In the figure, AC power from a commercial power source 1 is supplied to a rectifier 2, and the rectifier 2 converts AC power into predetermined DC power, outputs 56 V, and supplies it to a load 3. The assembled battery 4 is an assembled battery (rated voltage 48 V, rated capacity 100 Ah) in which 40 nickel-metal hydride battery cells (rated voltage 1.2 V, rated capacity 100 Ah) are connected in series, and 6 sets (1 system to 6 systems) It is installed.

  Each assembled battery 4 is charged via a connected charger 5 when the commercial power source 1 is active, and is connected in parallel to a wiring from the rectifier 2 to the load 3 via a discharger 7. ing. The assembled battery 4 reaches 64 V (1.6 V per cell) when fully charged, but the discharger 7 performs a step-down operation to maintain the output voltage at 55 V or less. Thus, since the output voltage of the discharger 7 is set to be equal to or lower than the output voltage (56V) of the rectifier 2, when the commercial power source 1 is valid, the output of the rectifier 2 is supplied to the load 3, and the rectifier 2 When the commercial power supply 1 is stopped due to a power failure or the like, the power output from the assembled battery 4 is supplied to the load 3 via the discharger 7. It is assumed that the operation of each charger 5 is controlled by a charging control means (not shown) as in the first embodiment.

  If the remaining charge of the assembled battery 4 is reduced to 90% (30 days elapse, c = 10%) when supplementary charging is performed in the same manner as in the first embodiment, the assembled battery is sequentially installed every 5 days. 4 is sufficient, and the minimum value of the ratio of the total remaining capacity to the total capacity at full charge is 94.17% by setting n = 6 in equation (2).

Also in the present embodiment, as in the first embodiment, when the required minimum ratio Q _min [%] of the total remaining capacity is determined in advance, the number of the assembled batteries 4 is set using Expression (3). It is also possible to obtain n. Further, the power supply system is designed by adjusting the required minimum ratio Q _min , the number n of the assembled batteries 4 and the capacity reduction c [%] for auxiliary charging using the formula (4), and the total remaining capacity is calculated. It is also possible to prevent the ratio to the total capacity at full charge from falling below Q _min [%].

As described above, the required minimum ratio of the total remaining capacity is defined as Q _min [%], and the remaining capacity decrease from full charge, which determines that supplementary charging is required again for one set of the assembled batteries, is expressed as c [%]. When n, Q _min and c are

を満たし、１組の組電池４に対して満充電から残容量がｃ［％］低下する時間をＴ、ｋを１からｎまでの自然数、ｍを０以上の整数とするとき、ｋ番目の前記組電池は、時刻（ｋ/ｎ＋ｍ)Ｔに前記補充電が行われるようにすることによって、システムの合計残容量の低下を減らすことができ、余分に設置する蓄電池を減らすことができ、蓄電池の劣化を抑制することができる。

When the time when the remaining capacity is reduced by c [%] from a full charge to a set of assembled batteries 4 is T, k is a natural number from 1 to n, and m is an integer greater than or equal to 0, the kth The assembled battery can reduce the decrease in the total remaining capacity of the system by reducing the total remaining capacity of the system by performing the auxiliary charging at time (k / n + m) T. Can be prevented.

  In each embodiment of the present invention, one charger 5 is connected to one set of assembled batteries 4, but one charger 5 is shared and used by a plurality of assembled batteries 4. It is also possible. A changeover switch may be provided between one charger 5 and the plurality of assembled batteries 4 so as to perform switching so that the assembled battery 4 to be charged is charged.

  In each embodiment of the present invention, a DC power supply system using a nickel metal hydride storage battery has been described as an example. However, the present invention can also be applied to a DC power supply system equipped with a secondary battery such as a lead storage battery or a lithium ion storage battery. . Further, in addition to the DC power supply system, the present invention can also be applied to a storage battery system that does not supply a load and only stores the battery while maintaining a high remaining battery capacity.

Below, the effect produced by this invention is demonstrated.
(1) In a DC power supply system composed of a plurality of assembled batteries, when each assembled battery independently determines a remaining capacity drop due to self-discharge and performs supplementary charging, the remaining capacity of all the assembled batteries is simultaneously Since there is a possibility of lowering, there is a problem that it becomes necessary to mount an extra storage battery, and the cost and installation space increase.

According to the present invention, it is possible to reduce the reduction in the total remaining capacity of the system and reduce the number of storage batteries to be installed, so that cost and space can be saved.
(2) In order to prevent a decrease in the total remaining capacity, there is a problem that deterioration of the storage battery is promoted when the auxiliary charging frequency is increased.

  According to the present invention, it is possible to suppress a decrease in the total remaining capacity without increasing the auxiliary charging frequency, and thus it is possible to suppress the deterioration of the storage battery.

It is a figure explaining the example of embodiment of this invention. It is a figure explaining the remaining capacity progress of each assembled battery of implementation of this invention. It is a figure explaining the example of embodiment of this invention. It is a figure explaining the remaining capacity progress of each assembled battery of implementation of this invention. It is a block diagram of the direct-current backup power supply system which combined the rectifier, the charger, the discharger, and a plurality of sets of assembled batteries.

Explanation of symbols

1: commercial power supply, 2: rectifier, 3: load, 4: assembled battery, 5: charger, 6: diode, 7: discharger, 8: charge control means.

Claims (4)

In a DC power supply system having a plurality of assembled batteries, a charger, and a charge control means for controlling a charging schedule of the charger as components,
The number of assembled battery sets is n, the auxiliary charging unit time is T, the auxiliary charging ordinal number is an integer m of 0 or more, and from the full charging of the assembled battery when the auxiliary charging of each assembled battery is started When the remaining capacity decrease rate is c [%], and the ratio of the required minimum remaining capacity to the fully charged capacity of the entire assembled battery is Q _min [%],
n, Q _min and c are Q _min ≦ 100% − (c / 2) (1 + 1 / n)
To meet
When k is a natural number from 1 to n,
The DC power supply system, wherein at time (k / n + m) T, supplementary charging of the k-th assembled battery is started. In a method for charging a DC power supply system comprising a plurality of assembled batteries, a charger, and a charge control means for controlling a charging schedule of the charger, as constituent elements,
The number of assembled battery sets is n, the auxiliary charging unit time is T, the auxiliary charging ordinal number is an integer m of 0 or more, and from the full charging of the assembled battery when the auxiliary charging of each assembled battery is started When the remaining capacity decrease rate is c [%], and the ratio of the required minimum remaining capacity to the fully charged capacity of the entire assembled battery is Q _min [%],
n, Q _min and c are Q _min ≦ 100% − (c / 2) (1 + 1 / n)
Is satisfied,
When k is a natural number from 1 to n,
A charging method for a DC power supply system, wherein at time (k / n + m) T, supplementary charging of the k-th assembled battery is started. The DC power supply system according to claim 1,
It has a rectifier that converts AC power into DC power,
Each of the assembled batteries is connected in parallel via a diode that passes power only in the discharge direction of the assembled battery, and is further connected in parallel to a power supply line from the rectifier to the load,
The maximum value of the charging voltage to the assembled battery is set to be equal to or lower than the output voltage of the rectifier. The DC power supply system according to claim 1,
It has a rectifier that converts AC power into DC power,
Each of the assembled batteries is connected in parallel via a discharger, and further connected in parallel to a power supply line from the rectifier to the load,
The output voltage of the discharger is set to be equal to or lower than the output voltage of the rectifier.

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