JP2011188700A - Power supply system, discharge control method, and discharge control program - Google Patents

Power supply system, discharge control method, and discharge control program Download PDF

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JP2011188700A
JP2011188700A JP2010054175A JP2010054175A JP2011188700A JP 2011188700 A JP2011188700 A JP 2011188700A JP 2010054175 A JP2010054175 A JP 2010054175A JP 2010054175 A JP2010054175 A JP 2010054175A JP 2011188700 A JP2011188700 A JP 2011188700A
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storage battery
series
battery units
units
discharge
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JP5314626B2 (en
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Takahisa Masashiro
Akihiro Miyasaka
Keita Takahashi
Akira Yamashita
明宏 宮坂
山下  明
尊久 正代
慶多 高橋
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Nippon Telegr & Teleph Corp <Ntt>
日本電信電話株式会社
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    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10Energy storage
    • Y02E60/12Battery technologies with an indirect contribution to GHG emissions mitigation

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power supply system which removes variations in the SOCs (charging rates) of a plurality of systems of battery units which are connected in parallel and the battery voltages during discharges and completely discharges the battery units of all the systems. <P>SOLUTION: In a configuration, dischargers 31, 32, ..., 3N at every system controlling the current values of discharge currents supplied to a load 2 from each of a plurality of systems of the battery units connected in parallel are connected to each of a plurality of systems of respective battery unit. In the configuration, a control circuit 90 computes the difference between the charging statuses of two systems of mutually adjacent battery units 4i and 4(i+1), such as, the SOCs or the battery voltages regarding each of a plurality of systems of the battery units 41, 42, ..., 4N. In the configuration, the control circuit controls the current values of the discharge currents of two systems of the dischargers 3i and 3(i+1) connected corresponding to two systems of the battery units 4i and 4(i+1) to an equal value, when the difference is a preset charging-status threshold value, such as, an SOC threshold or a battery-voltage threshold or less. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a power supply system, a discharge control method, and a discharge control program. More specifically, the present invention relates to a power supply system, a discharge control method, and a discharge control program that control a discharge operation in a power supply system including a plurality of storage battery units.

  Nickel metal hydride storage batteries and nickel cadmium batteries are generally charged at a constant current. Since a large storage battery requires a large amount of current for charging, in a storage battery system in which multiple series are connected in parallel, charging is not performed for all storage batteries at the same time, but is performed for each of the divided series. Often. After charging, the storage battery is placed in an open circuit state, and due to self-discharge, the charging rate (SOC; State of Charge: the amount of electricity being charged relative to the capacity) falls below a certain limit. At this stage, the charging operation of charging with a constant current is repeated until the battery is fully charged again. Such a charging operation is usually called supplementary charging in the sense of compensating for self-discharge.

  As a specific example, in the DC power supply system for mobile phone base stations disclosed in 'High Performance Backup Power Supply System' (IEICE / IEEE INTELEC'03) by K. Saito et al. 10 nickel-metal hydride storage battery cells are connected in series to form a storage battery module, and further, four storage battery modules are connected in series to constitute a series of storage battery units. Further, the storage battery units are connected in parallel in two lines, and the auxiliary charging is performed one line at a time with a current of 10A. Here, the auxiliary charging is designed to be performed when the SOC of the storage battery unit is reduced to about 90% by self-discharge. At this time, the SOCs of the storage battery units do not necessarily match in the two series. The SOC difference between the two storage battery units is maximized immediately after one of the storage battery units is supplementarily charged and immediately before the other storage battery unit is supplementarily charged, and the SOC difference is about 10%. There is also. However, this SOC difference is a case where the estimation of the SOC of the storage battery unit is correct, and actually, the SOC difference between the two series of storage battery units may further increase.

K. Saito, T. Shodai, A. Yamashita, and H. Wakaki; 'High Performance Backup Power Supply System', IEICE / IEEE INTELEC'03 (The 25th International Telecommunications Energy Conference), 261-266 ( 2003)

  As described above, when a plurality of storage battery units are connected in parallel and connected to a load in a state where there is a difference in SOC between storage battery units of different systems, the SOC of the battery is generally relatively A large current flows from the storage battery unit of the higher series, and a small current flows from the storage battery unit of the relatively low SOC, so the SOC difference between the two storage battery units gradually decreases. Eventually, there is a possibility of obtaining a state in which the discharge ends almost simultaneously.

  However, when a storage battery unit is configured using a nickel hydride storage battery or a nickel cadmium storage battery as a storage battery cell, the voltage difference due to the difference in the SOC of the storage battery unit is small, and the internal resistance also changes according to the SOC. The storage battery unit of the higher SOC series does not always flow a larger current than the storage battery unit of the lower SOC series. Therefore, even if discharged, the SOC of the two series storage battery units does not flow. The difference may not shrink.

  If the discharge current from the storage battery unit of the lower SOC series is not smaller than the discharge current from the storage battery unit of the higher SOC series, the storage battery unit of the lower SOC series is the first. It reaches the end-of-discharge voltage and is disconnected from the power supply system. In this case, the discharge concentrates on the remaining battery units, and as a result, the power supply system exceeds the maximum current value. Alternatively, the discharge operation is stopped when the voltage drops greatly and falls below the minimum voltage value. Thus, when the power supply system stops discharging, the storage battery unit still has a remaining capacity. That is, a state occurs in which the entire capacity of the storage battery cannot be used up.

  In the system of Non-Patent Document 1, a discharger is connected to each storage battery unit series. However, the function of the discharger is to have only two functions of step-up / step-down and current limiting. When there is a difference in SOC between two battery units, the discharge current is controlled. Thus, it does not have a function of reducing the SOC difference.

  As described above, in the case of a storage battery unit using a nickel hydride storage battery or nickel cadmium storage battery that is supplemented (intermittently charged) with a constant current, it has only the functions of step-up / step-down and current limiting, and the discharge current can be set to an arbitrary value. Even if a conventional discharger that does not have a control function is used, it is difficult to eliminate variations in SOC and storage battery voltage between the two series of storage battery units during discharge. In order to make the SOC and storage battery voltage uniform between the two storage battery units, it is necessary to simultaneously charge the two series of storage battery units simultaneously. However, for that purpose, it is necessary to connect one charger to each storage battery unit series, which is only used for auxiliary charging, and the wiring must also correspond to the current value of simultaneous charging. It is not an economically advantageous solution.

(Object of the present invention)
The present invention has been made to solve the above-described problems, and the present invention eliminates variations in SOC (charge rate) and storage battery voltage of storage battery units connected in parallel during discharging, It is an object of the present invention to provide a power supply system, a discharge control method, and a discharge control program for completely discharging a storage battery unit of a group.

  The present invention comprises the following technical means in order to solve the above-mentioned problems.

  The first technical means includes a storage battery unit having a configuration in which a plurality of storage battery cells are connected in series, a plurality of storage battery units connected in parallel, and each discharge current supplied to each load from the plurality of storage battery units. A discharger for each series capable of controlling the current value of the battery, and the discharger for each series connected to the storage battery unit based on a result of measuring a charging state of each of the storage battery units of the plurality of series. A control circuit that controls and controls a current value of a discharge current from the storage battery unit, wherein the control circuit relates to a charging status of each of the storage battery units of the plurality of series, Calculate the difference between the charging statuses of the two storage battery units adjacent to each other, and the difference is less than or equal to the preset charging status threshold If so, the discharge device for each of the series connected to the two series of storage battery units is controlled to control the current value of the discharge current from the two series of storage battery units to an equal value. To do.

  According to a second technical means, in the power supply system according to the first technical means, the control circuit measures a storage battery voltage of each of the storage battery units of the plurality of series as the charging state, and two series of adjacent ones. When the difference between the storage battery voltages of the storage battery units is calculated and the difference is less than or equal to the storage battery voltage threshold set in advance as the charging status threshold, for each of the series connected to the two storage battery units And controlling the current values of the discharge currents from the two series of storage battery units to be equal to each other.

  According to a third technical means, in the power supply system according to the first technical means, the control circuit measures an SOC (State of Charge) of each of the storage battery units of the plurality of series as the charging state, and is adjacent to each other. When the difference between the SOCs of the two storage battery units that match each other is calculated and the difference is equal to or lower than the SOC threshold value that is set in advance as the charging state threshold, the two battery storage units connected to the two battery storage units Controlling the discharger for each series, the current values of the discharge currents from the two series of storage battery units are controlled to be equal.

  According to a fourth technical means, in the power supply system according to any one of the first to third technical means, a difference between the charging statuses of the two series of storage battery units adjacent to each other is equal to or less than the charging status threshold value. In this case, the equal value controlled as the current value of the discharge current from the two series of storage battery units is the current value of the maximum discharge current that can be output by both of the two series of storage battery units. To do.

  According to a fifth technical means, the storage battery units formed by connecting a plurality of storage battery cells in series are connected in parallel to a plurality of series, and based on the result of measuring the charging status of each of the storage battery units of the plurality of series, A discharge control method of a power supply system for controlling a discharge value for each series connected to each storage battery unit and controlling a current value of a discharge current supplied from each of the plurality of series storage battery units to the load, Regarding the charging status of each storage battery unit, the difference between the charging statuses of the two series of storage battery units adjacent to each other is calculated, and when the difference is less than or equal to the preset charging status threshold, the two series The discharger for each of the series connected to the storage battery unit is controlled, and the current value of the discharge current from the two series of storage battery units And controlling a value equal.

  According to a sixth technical means, in the discharge control method according to the fifth technical means, the storage battery voltage of each of the plurality of storage battery units is measured as the state of charge, and the storage batteries of two storage battery units adjacent to each other When the difference between the voltages is calculated and the difference is less than or equal to the storage battery voltage threshold set in advance as the charge state threshold, the discharger for each of the series connected to the two series of storage battery units And controlling the current values of the discharge currents from the two series of storage battery units to be equal to each other.

  A seventh technical means is the discharge control method according to the fifth technical means, wherein the SOC (State of Charge) of each of the storage battery units of the plurality of series is measured as the charging state, and two series adjacent to each other are measured. When the difference between the SOCs of the storage battery units is calculated and the difference is equal to or lower than the SOC threshold set in advance as the charging state threshold, the difference between the two battery storage units connected to the two battery storage units By controlling the discharger, the current value of the discharge current from the two series of storage battery units is controlled to be equal.

  According to an eighth technical means, in the discharge control method according to any one of the fifth to seventh technical means, a difference between the charging statuses of two series of storage battery units adjacent to each other is equal to or less than the charging status threshold value. The equal value controlled as the current value of the discharge current from the two series of storage battery units is the current value of the maximum discharge current that can be output by both of the two series of storage battery units. It is characterized by.

  The ninth technical means is characterized in that the discharge control method according to any one of the fifth to eighth technical means is a discharge control program implemented as a program executable by a computer.

  According to the power supply system, the discharge control method, and the discharge control program of the present invention, since the structure is employed, the following effects can be obtained.

  In other words, since a mechanism for controlling the discharge current value supplied to the load from each of the plurality of storage battery units is realized according to the charging status of each of the plurality of storage battery units connected in parallel, for example, the SOC (charge rate) or the storage battery voltage. The variation in SOC (charge rate) and storage battery voltage of each of the plurality of storage battery units can be eliminated during the discharge operation to the load side, and thus the remaining capacity of the plurality of storage battery units is reduced at the end of the discharge operation. All of the plurality of storage battery units can be completely discharged without variation.

1 is a system configuration diagram illustrating an example of a power supply system including a plurality of storage battery units that operate as a backup power supply for a DC power supply such as a rectifier as a power supply system according to the present invention. It is a system configuration figure showing an example system configuration used for explaining an example of discharge control operation of a power supply system concerning the present invention. It is a flowchart which shows an example which controls the discharge operation of the power supply system shown in FIG. 6 is a flowchart showing another example of controlling the discharge operation of the power supply system shown in FIG. 1. It is a graph which shows the time change of the discharge current discharged from the storage battery unit of 2 series at the time of using the conventional type discharger which cannot switch the maximum discharge current. It is a graph which shows the time change of SOC of 2 series storage battery units at the time of using the conventional type discharger which cannot switch the maximum discharge current. It is a graph which shows the time change of the discharge current discharged from the storage battery unit of 2 series in the case of the power supply system shown in FIG. 2 using the discharger which can switch a maximum discharge current. It is a graph which shows the time change of SOC of the storage battery unit of 2 series | strains in the case of the power supply system shown in FIG.

  Hereinafter, an example of a preferred embodiment of a power supply system, a discharge control method, and a discharge control program according to the present invention will be described in detail with reference to the drawings. In the following description, the power supply system and the discharge control method according to the present invention will be described. However, the discharge control method may be implemented as a discharge control program that can be executed by a computer, or the discharge control may be performed. Needless to say, the program may be recorded on a computer-readable recording medium.

(Features of the present invention)
The present invention relates to charging between two storage battery units adjacent to each other in a power supply system having a configuration in which a plurality of storage battery units (single cells) connected in series as a power storage unit are connected in series. When the difference in the situation, for example, the difference in the storage battery voltage or the SOC, is less than or equal to the preset charge situation threshold, for example, the storage battery voltage threshold or the SOC threshold, the discharge currents of the two series of storage battery units are controlled to the same current value. By repeating the operation, finally, when the difference in the charging status between the storage battery units of all series, for example, the difference in the storage battery voltage or the SOC, becomes lower than the preset charging status threshold such as the storage battery voltage threshold or the SOC threshold. Is characterized in that the discharge currents of the storage battery units of all series are controlled to be equal.

  As a result, the initial values of the charging status of the storage battery units of each series are different from each other, for example, the initial value of the storage battery voltage or SOC, and further, even if the storage battery unit of the higher storage battery voltage or SOC and the lower series of Regardless of the relationship between the discharge current and the storage battery unit, the remaining capacity unbalance between the storage battery units can be eliminated during the discharge operation, and the discharge end voltage can be made uniform. The amount of electricity stored in the storage battery unit can be used up.

(Embodiment of the present invention)
Hereinafter, although an example of the present invention will be described in detail with respect to the embodiment of the present invention, it is needless to say that the present invention is not limited to such an embodiment without departing from the gist described in the present embodiment.

(Configuration example of power supply system according to the present invention)
In general, in the case of realizing a high-output power supply system using, for example, a nickel-metal hydride storage battery, as described in Non-Patent Document 1, a nickel-metal hydride storage cell (average voltage 1.2 V, A series of 10 rated current capacities (95 Ah) connected in series is used as one storage battery module, and 4 storage battery modules are connected in series to form a single storage battery unit (output 5 kWh). In order to obtain the required output, N series (N: positive integer. For example, in the case of 30 kWh output, N = 6) is configured in parallel connection.

  FIG. 1 is a system configuration diagram showing an example of a power supply system including a plurality of storage battery units that operate as a backup power supply for a DC power supply such as a rectifier as a power supply system according to the present invention. A battery is provided for each battery unit of each series, and a charger for charging the battery series of multiple series is provided in common for the battery series of multiple series, and the DC power supply is a rectifier that rectifies commercial AC power. The case where it is used is shown.

  In the configuration example shown in FIG. 1, N series storage battery units of series 1 storage battery unit 41, series 2 storage battery unit 42,..., Series N storage battery unit 4N are connected in parallel as a storage battery system from a plurality of series storage battery units. Thus, a power storage unit is formed. A plurality of storage battery units employs a configuration in which a plurality of storage battery modules in which a plurality of nickel hydride batteries or nickel cadmium battery single cells are connected in series are connected in series.

  Further, from the control circuit 90, the battery voltage output from each of the N system storage battery units is within the allowable voltage range of the load 2 and the current value of the discharge current supplied to the load 2 can be controlled. By controlling the above, the battery voltage output from each of the series 1 storage battery unit 41, the series 2 storage battery unit 42,..., The series N storage battery unit 4N is increased or decreased, or the current value of the discharge current is set to an arbitrary value. The series 1 discharger 31, the series 2 discharger 32,..., The series N discharger 3 </ b> N are assigned to each series as dischargers for each series capable of performing control (for example, switching to two maximum and small maximum discharge currents). Corresponding to the storage battery unit. In other words, the series 1 discharger 31, the series 2 discharger 32,..., The series N discharger 3N discharges the series 1 storage battery unit 41, the series 2 storage battery unit 42,. The current value is controlled.

  Further, in FIG. 1, a single common charger 10 is provided as a charger for charging a plurality of storage battery units from the rectifier 1 via the charger changeover switch 60, and a control circuit By switching the charger changeover switch 60 under the control from 90, any one of the series 1 storage battery unit 41, the series 2 storage battery unit 42,..., The series N storage battery unit 4N can be charged by the common charger 10. It has become a structure. In some cases, on the charger side, similarly to the discharger side, instead of using the common charger 10, a plurality of chargers are used to connect the series 1 storage battery unit 41, the series 2 storage battery unit 42,. You may make it arrange | position corresponding to each N storage battery unit 4N.

  Further, in FIG. 1, in order to grasp the charging status of each of the storage battery units of the plurality of series in the control circuit 90, for example, a measurement line for measuring the storage battery voltage of each of the storage battery units of the plurality of series, In order to calculate the SOC of each of a plurality of storage battery units that is one of the evaluation scales of the situation, a shunt resistor is further connected in series to each of the plurality of storage battery units, and the voltage across each shunt resistance is measured. A measurement line for this purpose is connected to the control circuit 90.

  That is, the measurement lines for measuring the storage battery voltage of the series 1 storage battery unit 41, the series 2 storage battery unit 42,..., The series N storage battery unit 4N are the series 1 storage battery voltage measurement line 71, the series 2 storage battery voltage measurement line 72,. The series N storage battery voltage measurement line 7N is laid between each storage battery unit and the control circuit 90. Further, a series 1 storage battery unit 41, a series 2 storage battery unit 42,..., A series N storage battery unit 4N are connected in series, and a series 1 shunt resistor 51, a series 2 shunt resistor 52,. Measurement lines for measuring the voltage at both ends of each shunt resistor connected are a series 1 shunt resistance voltage measurement line 81, a series 2 shunt resistance voltage measurement line 82,..., A series N shunt resistance voltage measurement line 8N. It is laid between each shunt resistor and the control circuit 90.

  In the power supply system shown in FIG. 1 having the above-described configuration, each storage battery unit (series 1 storage battery unit 41, 41) is changed by changing the connection state of the charger changeover switch 60 in accordance with the control of the control circuit 90. The series 2 storage battery unit 42,..., The series N storage battery unit 4N) are appropriately charged by the output of the rectifier 1 via the common charger 10, and further, the respective dischargers (series 1 discharger 31, series 2 discharger 32). ,..., And the series N discharger 3N) are configured to supply power to the load 2 in a manner in which the current value of the discharge current is appropriately controlled. Here, the plurality of dischargers (series 1 discharger 31, series 2 discharger 32,..., Series N discharger 3N) are electrically connected on the output side, connected to the load 2, and common The charger 10 is configured to be electrically connected to the rectifier 1 on its input side, and the battery system can be expanded by adding a discharger and a storage battery unit.

  Next, an example of the operation for performing the discharge control of the power supply system according to the present invention including a plurality of storage battery units will be described in detail with reference to the system configuration diagram of FIG. FIG. 2 is a system configuration diagram showing a system configuration example used to explain an example of the discharge control operation of the power supply system according to the present invention, and in order to simplify the explanation, a plurality of series of storage batteries shown in FIG. A case where the unit is limited to two series of N = 2 is shown. In addition, a nickel metal hydride storage battery shall be used as a unit cell (storage battery cell) which comprises a storage battery unit.

  That is, in FIG. 2, a storage battery module was formed by connecting 10 nickel hydride storage battery cells with a rated current capacity of 95 Ah in series and placing them in a case. Further, four units of the storage battery modules are connected in series to form a unit unit. As shown in FIG. 2, the first storage battery module 411 for the series 1, the second storage battery module 412 for the series 1, the third unit for the series 1 A series 1 storage battery unit 41 comprising a storage battery module 413, a series 1 fourth storage battery module 414, a series 2 first storage battery module 421, a series 2 second storage battery module 422, a series 2 third storage battery module 423, a series 2 The 2 series with the series 2 storage battery unit 42 which consists of the 4th storage battery module 424 for was comprised.

  Further, a series 1 for supplying an appropriate discharge current to the load 2 side corresponding to each series of storage battery units by connecting two series 1 storage battery units 41 and series 2 storage battery units 42 in parallel. By connecting the discharger 31 and the series 2 discharger 32 and switching and connecting one common charger 10 to the storage battery units of each series via the charger changeover switch 60, a rectifier (in FIG. The rectifier 1 shown in FIG. 1 is omitted, and only the rectifier connection terminals 1a and 1b are described.

  In FIG. 2, the storage battery voltages of the two series 1 storage battery units 41 and the series 2 storage battery units 42 are voltage detection provided for each storage battery module or each nickel hydride storage battery cell constituting each storage battery unit. It is detected by the means and transferred to the control circuit 90 via the storage battery voltage measurement lines connected correspondingly.

  In the example shown in FIG. 2, a measurement line is laid for each storage battery module. Regarding the series 1 storage battery unit 41, the series 1 first storage battery module 411, the series 1 second storage battery module 412, and the series 1 first A voltage detection means is arranged for each of the three storage battery modules 413 and the fourth storage battery module 414 for the series 1, and from each voltage detection means, the first storage battery voltage measurement line 711 for the series 1 and the second storage battery voltage for the series 1 The data is transferred to the control circuit 90 via the measurement line 712, the third storage battery voltage measurement line 713 for series 1, and the fourth storage battery voltage measurement line 714 for series 1.

  On the other hand, with respect to the series 2 storage battery unit 42, voltage detection is performed for each of the series 2 first storage battery module 421, the series 2 second storage battery module 422, the series 2 third storage battery module 423, and the series 2 fourth storage battery module 424. Means are arranged, and from each voltage detection means, first battery voltage measurement line for series 2 721, second storage battery voltage measurement line for series 2 722, third storage battery voltage measurement line for series 2 723, for series 2 It is transferred to the control circuit 90 via the fourth storage battery voltage measurement line 724.

  In the control circuit 90, the series 1 storage battery unit 41, the series, based on the result measured by each storage battery voltage measurement line as one of the evaluation measures of the charging status in each of the series 1 storage battery unit 41 and the series 2 storage battery unit 42. The storage battery voltage of each of the two storage battery units 42 is calculated.

  In FIG. 2, both-end voltages (shunt resistance voltages) at the series 1 shunt resistor 51 and the series 2 shunt resistor 52 connected in series to the two series 1 storage battery units 41 and the series 2 storage battery units 42 are respectively Then, the data is transferred to the control circuit 90 via the series 1 shunt resistance voltage measurement line 81 and the series 2 shunt resistance voltage measurement line 82 which are connected to each other. In the control circuit 90, the series 1 storage battery unit 41 and the series calculated from the result measured by each storage battery voltage measurement line as one of the evaluation measures of the charging status in each of the series 1 storage battery unit 41 and the series 2 storage battery unit 42. From the storage battery voltage of each of the two storage battery units 42 and the shunt resistance voltage measured by the series 1 shunt resistance voltage measurement line 81 and the series 2 shunt resistance voltage measurement line 82, the series 1 storage battery unit 41 and the series 2 storage battery unit 42 respectively. Calculate the SOC.

  Further, the control circuit 90 calculates the difference between the storage battery voltages (storage battery voltage difference) between the series 1 storage battery unit 41 and the series 2 storage battery unit 42 calculated as described above as the storage battery between the adjacent two series of storage battery units 41 and 42. The storage battery voltage between the series 1 storage battery unit 41 and the series 2 storage battery unit 42 calculated as a voltage difference and compared with a storage battery voltage threshold set in advance in the internal memory in the control circuit 90 as an example of the charging state threshold When the voltage difference of the battery is lower than the storage battery voltage threshold value, the system 1 discharger 31 and the system 2 discharger 32 are connected via the system 1 discharger control line 91 and the system 2 discharger control line 92. Then, the control signal is transmitted to set the current values of the discharge currents from both the series 1 storage battery unit 41 and the series 2 storage battery unit to the same value.

  Further, the control circuit 90 calculates the SOC difference (SOC difference) between the series 1 storage battery unit 41 and the series 2 storage battery unit 42 calculated as described above as the SOC difference between the adjacent two series of storage battery units 41 and 42. The calculated SOC difference between the series 1 storage battery unit 41 and the series 2 storage battery unit 42 is obtained by comparison with an SOC threshold value that is preset as another example of the charging state threshold value in the internal memory in the control circuit 90. If the SOC threshold value is lower than the SOC threshold value, a control signal is transmitted to the series 1 discharger 31 and the series 2 discharger 32 via the series 1 discharger control line 91 and the series 2 discharger control line 92. Then, the current value of the discharge current from both the series 1 storage battery unit 41 and the series 2 storage battery unit is set to an equal value.

  Here, the control circuit 90 is composed of a microcomputer (MPU) or the like, and two adjacent storage battery units, that is, the series 1 storage battery unit 41 and the series 2 are controlled by a control program (discharge control program) executed in the microcomputer. The charging state of the storage battery unit 42 that changes every moment is grasped, and the series 1 discharger 31 and the series 2 discharger 32 connected to the two storage battery units 41 and 42 are controlled according to the grasped charging state. Then, the discharge current value from each of the two storage battery units 41 and 42 is changed to an arbitrary value (for example, as the maximum discharge current value that each of the two storage battery units 41 and 42 can output in common) It is also possible to arbitrarily switch between two predetermined large and small current values).

  In the configuration example of the power supply system shown in FIG. 2, each of two adjacent storage battery units of the series 1 storage battery unit 41 and the series 2 storage battery unit 42 has four storage battery modules, that is, as described above. First battery module 411 for series 1, second storage battery module 412 for series 1, third storage battery module 413 for series 1, fourth storage battery module 414 for series 1, first storage battery module 421 for series 2, first series battery for series 2 Each of the two storage battery modules 422, the third storage battery module 423 for series 2 and the fourth storage battery module 424 for series 2 is connected in series, and each storage battery module is a nickel hydride storage battery having a rated current capacity of 95 Ah. Ten cells are connected in series and each is housed in a case.

  In addition, the two series of storage battery units 41 and 42 are connected in parallel, and one terminal of each is connected to the rectifier via the series 1 discharger 31 and the series 2 discharger 32. While being connected to the rectifier connection terminal 1a, it is connected to one rectifier connection terminal 1a via one common charger 10 connected via the charger changeover switch 60. The other terminals of the two series of storage battery units 41 and 42 are connected to the other rectifier connection terminal 1b to which the rectifier is connected via the series 1 shunt resistor 51 and the series 2 shunt resistor 52, respectively. The two series of storage battery units 41 and 42 are configured as a backup power source for the rectifier.

  A load to which discharge current is supplied from the rectifier or from the series 1 discharger 31 and the series 2 discharger 32 connected to the two series of storage battery units 41 and 42 forming the power storage unit of the backup power source, respectively. 2 is connected with a load that consumes 1.6 kW of power in the present embodiment.

  Here, the series 1 discharger 31 and the series 2 discharger 32 are controlled by the control circuit 90 so that the current value of the discharge current supplied to the load 2 from each of the series 1 storage battery unit 41 and the series 2 storage battery unit 42 is arbitrarily set. For example, in accordance with control from the control circuit 90, the same maximum discharge current value that can be output by both the series 1 storage battery unit 41 and the series 2 storage battery unit 42 is set. Thus, the current values of the discharge currents from the series 1 storage battery unit 41 and the series 2 storage battery unit 42 can be controlled to be equal to each other.

(Example of discharge operation of the power supply system shown in FIG. 1)
Next, in the control circuit 90 of the power supply system shown in FIG. 1 and FIG. 2, the flowchart shown in FIG. 3 and FIG. 4 shows an example of controlling the discharge operation for the load 2 depending on the charging status of the plurality of storage battery units. This will be described in further detail.

  FIG. 3 is a flowchart showing an example of controlling the discharge operation of the power supply system shown in FIG. 1. The discharge operation for the load is controlled according to the SOC of the plurality of storage battery units as the charging status of the plurality of storage battery units. An example is shown. FIG. 4 is a flowchart showing another example of controlling the discharging operation of the power supply system shown in FIG. 1, and the charging status of the plurality of storage battery units corresponds to the load depending on the storage battery voltage of the plurality of storage battery units. The example which controls discharge operation is shown. Here, the flowcharts of FIGS. 3 and 4 show an example of the operation of the discharge control method of the power supply system according to the present invention, and discharge to the load depending on the state of charge of the backup power supply using the nickel hydride storage battery An example of controlling the current value of the current is described.

(Control method of discharge current by SOC difference between storage battery units)
First, by using the flowchart of FIG. 3, the discharge currents of the plurality of storage battery units are controlled according to the SOC (charge rate) of the plurality of storage battery units as the charging status of the plurality of storage battery units forming the backup power source. The operation will be described.

  In FIG. 3, first, a unit counter i for designating the storage battery unit number and a module counter j for designating the number of the storage battery module in the storage battery unit are each initially set to ‘1’ (step S1). Thereafter, the storage battery voltage of the jth storage battery module 4ij constituting the storage battery unit 4i of the series i is measured via the j storage battery voltage measurement line 7ij for the series i (for example, the first storage battery unit 41 of the series 1 storage battery unit 41). The storage battery voltage of the 1 storage battery module 411 is measured via the first storage battery voltage measurement line 711 for series 1) (step S2).

  Further, it is confirmed whether or not the storage battery voltage of all the storage battery modules constituting the series i storage battery unit 4i has been measured (step S3). If there are still storage battery modules to be measured (NO in step S3) ), The module counter j is updated by “1” (step S4), the process returns to step S2, and the operation of measuring the storage battery voltage of the next storage battery module constituting the storage battery unit 4i of the series i is repeated.

  On the other hand, when the storage battery voltage of all storage battery modules constituting the storage battery unit 4i of series i is measured (YES in step S3), the storage battery voltage of each storage battery module constituting the storage battery unit 4i of series i is added. Then, the storage battery voltage of the storage battery unit 4i of the series i is calculated (step S5).

  Thereafter, the shunt resistance voltage of the series i shunt resistor 5i connected to the series i storage battery unit 4i is measured via the series i shunt resistance voltage measurement line 8i (for example, the first of the series 1 storage battery unit 41). The shunt resistance voltage of the series shunt resistor 51 is measured via the series 1 first storage battery voltage measurement line 711) (step S6).

  Next, based on the storage battery voltage of the series i storage battery unit 4i calculated in step S5 and the series i shunt resistance voltage measured in step S6, the SOC (charge rate) of the series i storage battery unit 4i is calculated. Calculate (step S7).

  After calculating the SOC of the series i storage battery units 4i, it is next checked whether the SOCs of all series storage battery units constituting the power supply system have been calculated (step S8). If the storage battery unit remains (NO in step S8), the unit counter i is updated to “1” (step S9), and the module counter j is returned to the initial state of “1” (step S10). Returning to step S2, the storage battery voltage measurement operation of the next storage battery module constituting the next series storage battery unit, the storage battery voltage calculation of the next series storage battery unit, the shunt resistance voltage measurement operation, and the next The calculation operation of the SOC of the storage battery units of the series is repeated.

  On the other hand, when the calculation of the SOCs of the storage battery units of all series constituting the power supply system is completed (YES in step S8), the unit counter i is returned to the initial state of '1' (step S11), and then the power supply system First, the difference between the SOC of the storage battery unit 4i of the series i and the SOC of the storage battery unit 4 (i + 1) of the series (i + 1) is obtained, and the two storage battery units 4i adjacent to each other. , 4 (i + 1) is calculated (step S12).

  Next, the calculated SOC difference between the two adjacent series of storage battery units 4i, 4 (i + 1) is compared with the SOC threshold value preset in the memory in the control circuit 90 as information indicating the charging state threshold value of the storage battery unit. (Step S13). When the calculated SOC difference between two adjacent storage battery units 4i, 4 (i + 1) exceeds the SOC threshold (NO in step S13), both adjacent two storage battery units 4i, 4 (i + 1) Considering that there is still a gap in the SOC (charge rate), the series i discharger 3i connected to each of the two series of storage battery units 4i and 4 (i + 1) adjacent to each other, the series (i + 1) discharge Without controlling the electric device 3 (i + 1), the discharging operation for the load 2 is continued as it is.

  On the other hand, when the calculated SOC difference between the adjacent two series of storage battery units 4i, 4 (i + 1) is within the SOC threshold value (YES in step S13), both of the two series of storage battery units 4i, 4 (i + 1) It is determined that the SOCs (charge rates) of the two batteries are substantially equal, and the series i discharger 3i and the series (i + 1) discharger to which the two adjacent series battery storage units 4i and 4 (i + 1) are respectively connected 3 (i + 1) is controlled via the series i discharger control line 9i and the series (i + 1) discharger control line 9 (i + 1), and the series i storage battery unit 4i and the series (i + 1) storage battery unit 4 (i + 1) respectively. Current value of the discharge current supplied to the load 2 from a predetermined discharge current value (for example, two series of series i storage battery units 4i, series (i + 1) storage battery units 4 i + 1) is set to a current value equal to the maximum discharge current value) that can be output from both (step S14).

  Thereafter, it is confirmed whether or not the SOC difference between two adjacent storage battery units has been calculated for all the storage battery units constituting the power supply system (step S15). If the matching battery units remain (NO in step S15), after updating the unit counter i by “1” (step S16), the process returns to step S12 and the next adjacent two battery units The calculation of the SOC difference, the comparison between the SOC difference between the next two adjacent storage battery units and the SOC threshold value, and the discharge current changing operation based on the comparison result are repeated.

  On the other hand, when the calculation operation of the SOC difference is completed for all adjacent storage battery units (YES in step S15), the discharge currents of the plurality of storage battery units are controlled according to the SOC (charge rate). End the operation.

  By performing the operation as described above, the variation in SOC (charge rate) between the two series of adjacent storage battery units 4i, 4 (i + 1) connected in parallel, and further, all the power storage units of the power supply system are configured. Variations in SOC (charge rate) between the storage battery units 41, 42,..., 4N can be eliminated during the discharge operation with respect to the load 2, and the storage battery units of all series can be completely discharged.

(Control method of discharge current by battery voltage difference between battery units)
Next, with reference to the flowchart of FIG. 4, the operation of controlling the discharge currents of the plurality of storage battery units according to the storage battery voltage of the plurality of storage battery units as the charging status of the plurality of storage battery units forming the backup power source. explain.

  In FIG. 4, first, similarly to the case of FIG. 3, the unit counter i for designating the storage battery unit number and the module counter j for designating the number of the storage battery module in the storage battery unit are each initially set to “1” ( Step S21). Thereafter, the storage battery voltage of the jth storage battery module 4ij constituting the storage battery unit 4i of the series i is measured via the j storage battery voltage measurement line 7ij for the series i (for example, the first storage battery unit 41 of the series 1 storage battery unit 41). The storage battery voltage of the 1 storage battery module 411 is measured via the first storage battery voltage measurement line 711 for series 1) (step S22).

  Further, it is confirmed whether or not the storage battery voltage of all storage battery modules constituting the storage battery unit 4i of the series i has been measured (step S23). If there are still storage battery modules to be measured (NO in step S23) ), The module counter j is updated by “1” (step S24), the process returns to step S2, and the operation of measuring the storage battery voltage of the next storage battery module constituting the storage battery unit 4i of the series i is repeated.

  On the other hand, when the storage battery voltage of all the storage battery modules constituting the storage battery unit 4i of the series i is measured (YES in step S23), each storage battery module constituting the storage battery unit 4i of the series i is measured as in FIG. By adding the storage battery voltage, the storage battery voltage of the storage battery unit 4i of the series i is calculated (step S25).

  Once the storage battery voltage of the storage battery unit 4i of the series i is calculated, it is checked whether or not the storage battery voltage of all the storage battery units constituting the power supply system has been calculated (step S26), and the storage battery voltage is still calculated. When the storage battery unit to be processed remains (NO in step S26), the unit counter i is updated to “1” (step S27), and the module counter j is returned to the initial state of “1” (step S27). S28), returning to step S22, the measurement operation of the storage battery voltage of the next storage battery module constituting the storage battery unit of the next series and the calculation operation of the storage battery voltage of the storage battery unit of the next series are repeated.

  On the other hand, when the calculation of the storage battery voltage of all series of storage battery units constituting the power supply system is completed (YES in step S26), the unit counter i is returned to the initial state of “1” (step S29), and then the power supply Among the storage battery units of each series constituting the system, first, the difference between the storage battery voltage of the storage battery unit 4i of the series i and the storage battery voltage of the storage battery unit 4 (i + 1) of the series (i + 1) is obtained. A storage battery voltage difference between the storage battery units 4i and 4 (i + 1) is calculated (step S30).

  Next, the calculated storage battery voltage difference between the adjacent two series of storage battery units 4i, 4 (i + 1) is set in advance in the memory in the control circuit 90 as information indicating the charging status threshold of the storage battery unit. (Step S31). When the calculated storage battery voltage difference between the two adjacent storage battery units 4i, 4 (i + 1) exceeds the storage battery voltage threshold (NO in step S31), the adjacent two storage battery units 4i, 4 (i + 1) ) Considering that there is still a gap between the storage battery voltages of both, the series i discharger 3i and the series (i + 1) discharger to which the two adjacent series of storage battery units 4i and 4 (i + 1) are connected, respectively. The discharge operation for the load 2 is continued without controlling 3 (i + 1).

  On the other hand, when the calculated storage battery voltage difference between the two adjacent storage battery units 4i, 4 (i + 1) is below the storage battery voltage threshold (YES in step S31), the two storage battery units 4i, 4 (i + 1) ) It is determined that the storage battery voltages of the two are substantially equal, and the series i discharger 3i and the series (i + 1) discharger 3 to which the two adjacent series storage battery units 4i and 4 (i + 1) are connected, respectively. (I + 1) is controlled via the series i discharger control line 9i and the series (i + 1) discharger control line 9 (i + 1), and from each of the series i storage battery unit 4i and the series (i + 1) storage battery unit 4 (i + 1). The current value of the discharge current supplied to the load 2 is set to a predetermined discharge current value (for example, two series of series i storage battery units 4i, series (i + 1) storage battery units. (I + 1) is set to a current value equal to the maximum discharge current value) that can be output from both (step S32).

  Thereafter, with respect to the storage battery units of all series constituting the power supply system, it is confirmed whether or not the storage battery voltage difference between two adjacent storage battery units has been calculated (step S33), and the storage battery voltage difference is still calculated. If there are remaining adjacent series of storage battery units (NO in step S33), the unit counter i is updated by “1” (step S34), and then the process returns to step S30 to return to the next two series of storage battery units. The calculation of the storage battery voltage difference between them, the comparison of the storage battery voltage difference between the next two adjacent storage battery units and the storage battery voltage threshold, and the operation of changing the discharge current based on the comparison result are repeated.

  On the other hand, when the calculation operation of the storage battery voltage difference is completed for all storage battery units adjacent to each other (YES in step S33), the operation of controlling the discharge currents of the plurality of storage battery units is performed according to the storage battery voltage. finish.

  By performing the operation as described above, variations in the storage battery voltage between the two series of adjacent storage battery units 4i, 4 (i + 1) connected in parallel, and further, all the storage battery units 41 constituting the power storage unit of the power supply system. , 42,..., 4N can be eliminated during the discharge operation for the load 2, and all series of storage battery units can be completely discharged.

(Example)
Next, regarding the power supply system, the discharge control method, and the discharge control program in the present embodiment as described above, the embodiment in the case of using the power supply system having the system configuration of FIG. This will be described in detail in a contrasted form.

(Comparative Example 1)
First, as Comparative Example 1, the maximum discharge current is controlled in place of the series 1 discharger 31 and the series 2 discharger 32 that have the same circuit configuration as that of FIG. 2 but can control the maximum discharge current. The discharge operation in the case of using the conventional dischargers 31A and 32A that cannot perform the above will be described.

  That is, in Comparative Example 1, the maximum discharge current value cannot be switched by fixing the maximum current value 30A and the step-down voltage 50.5V to the two systems of the series 1 storage battery unit 41 and the series 2 storage battery unit 42, respectively. The conventional dischargers 31A and 32A are connected, and the first SOC of the series 1 storage battery unit 41 is set to “1.0”, and the first SOC of the series 2 storage battery unit 42 is set to “0.9”. The battery was discharged until the storage battery voltage fell below a predetermined discharge end voltage of 40.0 V.

  As a result, the discharge time was 235 minutes, and the remaining capacity at the end of discharge was 11% for the series 1 storage battery unit 41 and 4% for the series 2 series 2 storage battery unit 42. That is, with respect to the discharge end voltage of 40.0 V, the remaining capacity is different between the two series of storage battery units 41 and 42 having different initial SOCs (charging rates), and all the two series of storage battery units Cannot be completely discharged.

(Comparative Example 2)
Next, as Comparative Example 2, the circuit configuration is the same as that of FIG. 2, but in the same manner as in Comparative Example 1, instead of the Series 1 discharger 31 and the Series 2 discharger 32 capable of controlling the maximum discharge current. In addition, the SOC difference between the series 1 storage battery unit 41 and the series 2 storage battery unit 42 regarding the discharge operation when the conventional dischargers 31A and 32A that cannot control the maximum discharge current are used is a comparative example. The discharge operation in the case of larger than 1 will be described.

  That is, also in the comparative example 2, the maximum current value 30A and the step-down voltage 50.5V are fixed to the two systems of the system 1 storage battery unit 41 and the system 2 storage battery unit 42, respectively, and the maximum discharge current value cannot be switched. From the first comparative example, the conventional SOCs 31A and 32A are connected, the first SOC of the series 1 storage battery unit 41 is “1.0”, and the first SOC of the series 2 storage battery unit 42 is “0.8”. Similarly, in the case where the difference in SOC (charge rate) was increased, similarly to the case of Comparative Example 1, the batteries were discharged until the storage battery voltage of each of the two systems fell below a predetermined discharge end voltage of 40.0 V.

  As a result, the discharge time was 214 minutes, which was shorter than that of Comparative Example 1, and the remaining capacity at the end of discharge was 17% for Series 1 storage battery unit 41 and 3% for Series 2 storage 2 storage battery unit 42, Comparative Example 1. As compared with, it was in a state of large variation. That is, with respect to the end-of-discharge voltage of 40.0 V, the remaining capacity is much different between the two series of storage battery units 41, 42 in which the initial SOC (charge rate) is significantly different from that in Comparative Example 1. It has become more difficult to completely discharge all the two battery storage units.

  The measurement results of the time change of the discharge current and the time change of the SOC in Comparative Example 2 are shown in FIGS. 5 and 6, respectively. That is, FIG. 5 is a graph showing the time change of the discharge current discharged from the two series of storage battery units 41 and 42 when the conventional dischargers 31A and 32A that cannot switch the maximum discharge current are used. 6 is a graph showing the time change of the SOC of the two series of storage battery units 41 and 42 when the conventional dischargers 31A and 32A that cannot switch the maximum discharge current are used. When conventional dischargers 31A and 32A in which the maximum discharge current cannot be controlled at all are used, as shown in FIG. 5, the discharge currents discharged from the two series of storage battery units 41 and 42 are the respective SOCs. As shown in FIG. 6, the time changes of the SOCs of both storage battery units 41 and 42 in the two series are lowered substantially in parallel.

  Therefore, when the discharge end voltage reaches 40.0 V, the remaining capacity of the series 2 storage battery unit 42 whose initial SOC was “0.8” has fallen to 3%, The remaining capacity of the series 1 storage battery unit 41 whose initial SOC was “1.0” is 17%. As a result, the average remaining capacity of the two storage battery units constituting the power supply system, that is, the series 1 storage battery unit 41 and the series 2 storage battery unit 42 is about 10%, and 10% of the total capacity remains without being completely discharged. It will end up.

  Next, in order to specifically confirm the effect of the embodiment of the present invention, the current values of the discharge currents of the series 1 storage battery unit 41 and the series 2 storage battery unit 42 are controlled to arbitrary values in the circuit configuration of FIG. As an example, a series 1 discharger 31 and a series 2 discharger 32 that can switch the current value of the maximum discharge current between two values of 20A and 30A are used as an example. A discharge operation in the power supply system of FIG. 2 will be described.

  That is, in Example 1, it is possible to switch between two values of the maximum current value 20A and 30A for the two systems of the system 1 storage battery unit 41 and the system 2 storage battery unit 42, and The series 1 discharger 31 and the series 2 discharger 32 having a step-down voltage of 50.5 V are connected, and the first SOC of the series 1 storage battery unit 41 is set to “1.0”, the series 2 as in the case of the comparative example 2. When the initial SOC of the storage battery unit 42 is “0.8” and the SOC difference between the two is wide, as in Comparative Examples 1 and 2, the storage battery voltage of each of the two systems is set to the end of discharge. It was discharged until the voltage dropped below 40.0V.

  Here, the maximum discharge current of the higher series 1 storage battery unit 41 having the higher first SOC of '1.0' is set to 30A, and the lower series 2 storage battery of the lower first SOC of '0.8'. The maximum discharge current of the unit 42 is set to 20 A, which is the smaller one, and the discharge operation is performed on the load 2. The SOC difference between the two battery storage units 41 and 42 during the discharge operation indicates the charging status threshold of the storage battery unit. When the SOC threshold value set in advance as one piece of information is reduced to, for example, “0.005” or less, it is considered that the charging status of the two series of storage battery units 41 and 42 is substantially the same, The control circuit 90 controls the series 2 discharger 32 via the series 2 discharger control line 92 so that the maximum discharge current of the series 2 storage battery unit 42 with the lower first SOC is also the first S C is to switch to the maximum discharge current equal to 30A series 1 battery unit 41 of higher.

  The SOCs of the two series of storage battery units 41 and 42 are calculated by the control circuit 90 periodically at predetermined time intervals, for example, every 10 seconds. That is, by the storage battery voltage of the series 1 storage battery unit 41 and the series 1 shunt resistance voltage measurement line 81 calculated from the results measured every 10 seconds by the four storage battery voltage measurement lines 711 to 714 on the series 1 side shown in FIG. Based on the series 1 shunt resistance voltage measured every 10 seconds, the SOC of the series 1 storage battery unit 41 is calculated and calculated from the results measured every 10 seconds by the four storage battery voltage measurement lines 721 to 724 on the series 2 side. The SOC of the series 2 storage battery unit 42 is calculated based on the storage battery voltage of the series 2 storage battery unit 42 and the series 2 shunt resistance voltage measured every 10 seconds by the series 2 shunt resistance voltage measurement line 82.

  FIG. 7 and FIG. 8 show the measurement results of the time change of the discharge current and the time change of the SOC in Example 1, respectively. That is, FIG. 7 shows the time change of the discharge current discharged from the two battery storage units 41 and 42 in the case of the power supply system shown in FIG. 2 using the dischargers 31 and 32 capable of switching the maximum discharge current. FIG. 8 is a graph showing the time change of the SOC of the two storage battery units 41 and 42 in the case of the power supply system shown in FIG. 2 using the dischargers 31 and 32 capable of switching the maximum discharge current. is there.

  In the case of using SOC (charge rate) as information indicating the charging status of the two series of storage battery units 41, 42, the maximum discharge current is set to 20A and 30A according to the SOC difference between the two series of storage battery units 41, 42. By using the dischargers 31 and 32 that can be switched between two large and small values, the discharge current discharged from the two series of storage battery units 41 and 42 is two series of storage battery units as shown in FIG. When the SOC difference between 41 and 42 exceeds a preset SOC threshold, for example, '0.0005' as one piece of information indicating the charging state threshold of the storage battery unit, the series 2 storage battery unit with the lower first SOC The maximum discharge current from 42 is suppressed to 20 A, which is smaller, and the maximum discharge current from the series 1 storage battery unit 41 having the higher first SOC As larger 30A, depending on the respective SOC, it continues independent in time variation, the discharging operation from each other.

  However, when the SOC difference between the two series of storage battery units 41 and 42 is lower than the SOC threshold, for example, “0.0005”, the charging status of the two series of storage battery units 41 and 42 is substantially the same. Considering that, the maximum discharge current from the series 2 storage battery unit 42 is also switched to 30 A, which is equal to the maximum discharge current from the series 1 storage battery unit 41. As a result, the discharge currents from the two series of storage battery units 41 and 42 show substantially the same time change, and as shown in FIG. It will descend in substantially the same state.

  Therefore, when the discharge end voltage reaches 40.0 V, the remaining capacities of both the series 1 storage battery unit 41 and the series 2 storage battery unit 42 are less than 1%, and both the series 1 storage battery unit 41 and the series 2 storage battery unit 42 As shown in FIG. 8, the discharge time is 232 minutes, and the discharge current can be greatly extended as compared with the case of Comparative Example 2 in which the discharge current cannot be controlled at all. I was able to.

  Next, as an evaluation scale indicating the charging state of the storage battery unit in the embodiment of the present invention, the discharge operation when the storage battery voltage of the storage battery unit is used instead of the SOC (charge rate) of the storage battery unit shown in Example 1 Will be described.

  Also in the second embodiment, as in the first embodiment, for the two series of the series 1 storage battery unit 41 and the series 2 storage battery unit 42, the maximum current value 20A and the maximum current value 20A between the two values, respectively. The series 1 discharger 31 and the series 2 discharger 32 that can be switched and the step-down voltage is 50.5 V are connected, and the storage battery voltages of the two series are determined in advance as in the case of Comparative Examples 1 and 2. The battery was discharged until the discharge end voltage fell below 40.0V.

  Here, the maximum discharge current of the series 1 storage battery unit 41 having the higher first storage battery voltage is set to 30A, which is the larger one, and the maximum discharge current of the series 2 storage battery unit 42 having the lower initial storage battery voltage is set to the smaller one. It is set to 20A, the discharge operation for the load 2 is performed, and the storage battery voltage difference between the two series of storage battery units 41 and 42 during the discharge operation is set in advance as another information indicating the charging state threshold of the storage battery unit. When the storage battery voltage threshold is reduced to, for example, “0.01 V” or less, it is considered that the charging status of the storage battery units 41 and 42 of the two series is substantially the same, and the control circuit 90 causes the series 2 release. The series 2 discharger 32 is controlled via the electrical control line 92, and the first SOC is also high for the maximum discharge current of the series 2 storage battery unit 42 having the lower first SOC. It was switched to the series 1 maximum discharge current equal to 30A of the battery unit 41.

  Note that the storage battery voltages of the two series of storage battery units 41 and 42 are calculated by the control circuit 90 periodically at predetermined time intervals, for example, every 10 seconds. That is, the storage battery voltage of the series 1 storage battery unit 41 is calculated from the results measured every 10 seconds by the four storage battery voltage measurement lines 711 to 714 on the series 1 side shown in FIG. The storage battery voltage of the series 2 storage battery unit 42 is calculated from the results measured every 10 seconds by the measurement lines 721 to 724, respectively.

  Even when the storage battery voltage is used as another information indicating the charging status of the two series of storage battery units 41 and 42, the maximum discharge current is 20A and 30A according to the storage battery voltage difference between the two series of storage battery units 41 and 42. Discharge currents discharged from the two series of storage battery units 41 and 42 by using the dischargers 31 and 32 that can be switched between two values of the same as in FIG. 7 of the first embodiment. If the storage battery voltage difference between the two series of storage battery units 41 and 42 exceeds a preset storage battery voltage threshold, for example, “0.01 V” as another information indicating the charging status threshold of the storage battery unit, While the maximum discharge current from the series 2 storage battery unit 42 with the lower storage battery voltage is suppressed to 20 A, the series 1 storage with the higher initial storage battery voltage As 30A larger the maximum discharge current from the pond unit 41, in response to each of the battery voltage, and continues the discharging operation in a separate time change each other.

  However, when the storage battery voltage difference between the two series of storage battery units 41 and 42 is less than the storage battery voltage threshold, for example, “0.01 V”, the charging status of the two series of storage battery units 41 and 42 is substantially the same. The maximum discharge current from the series 2 storage battery unit 42 is also switched to 30 A, which is equal to the maximum discharge current from the series 1 storage battery unit 41. As a result, the discharge currents from the two series of storage battery units 41 and 42 show substantially the same time change, and the time changes in the remaining capacity of the two series of storage battery units 41 and 42 also drop in a substantially similar state. Will do.

  Accordingly, when the discharge end voltage reaches 40.0 V, the remaining capacities of both the series 1 storage battery unit 41 and the series 2 storage battery unit 42 are less than 1%, as in the first embodiment, and the series 1 storage battery unit 41 In addition, all of the series 2 storage battery units 42 can be almost completely discharged, and the discharge time is 230 minutes, which is the same level as in the first embodiment, and the discharge current cannot be controlled at all. Compared with the case of 2, it was able to extend significantly.

(Explanation of effect of embodiment)
As described in detail above, in the present embodiment, a plurality of storage battery units are connected in accordance with the state of charge of each of the plurality of storage battery units 41, 42,..., 4N connected in parallel, for example, SOC (charge rate) or storage battery voltage. Since a mechanism for controlling the discharge current value supplied to the load 2 from each of 41, 42,... 4N is realized, variation in SOC (charge rate) and storage battery voltage of each of the plurality of storage battery units 41, 42,. This can be eliminated during the discharge operation to the load 2 side. Therefore, at the end of the discharge operation, the remaining capacity of the plurality of storage battery units 41, 42,... , 42,... 4N can be completely discharged.

DESCRIPTION OF SYMBOLS 1 ... Rectifier, 1a, 1b ... Rectifier connection terminal, 2 ... Load, 10 ... Common charger, 31 ... Series 1 discharger, 32 ... Series 2 discharger, 3N ... Series N discharger, 41 ... Series 1 storage battery unit, 42 ... Series 2 storage battery unit, 4N ... Series N storage battery unit, 51 ... Series 1 shunt resistance, 52 ... Series 2 shunt resistance, 5N ... Series N shunt resistance, 60 ... Charger changeover switch, 71 ... Series 1 storage battery voltage measurement line 72 ... Series 2 storage battery voltage measurement line, 7N ... Series N storage battery voltage measurement line, 81 ... Series 1 shunt resistance voltage measurement line, 82 ... Series 2 shunt resistance voltage measurement line, 8N ... Series N shunt resistance voltage measurement line, 90 ... Control circuit, 91 ... Series 1 discharger control line, 92 ... Series 2 discharger control line, 411 ... First storage battery module for series 1, 412 ... Second storage battery module for series 1, 413 ... Third storage battery module for row 1 414 ... Fourth storage battery module for series 1 421 ... First storage battery module for series 2 422 ... Second storage battery module for series 2 423 ... Third storage battery module for series 2 424 ... 4th storage battery module for series 2, 711 ... 1st storage battery voltage measurement line for series 1 712 ... 2nd storage battery voltage measurement line for series 1 713 ... 3rd storage battery voltage measurement line for series 1 714 ... 1st storage battery voltage measurement line for series 1 4 storage battery voltage measurement line, 721... Series 2 first storage battery voltage measurement line, 722... Series 2 second storage battery voltage measurement line, 723... Series 2 third storage battery voltage measurement line, 724. Voltage measurement line.

Claims (9)

  1. A storage battery unit having a configuration in which a plurality of storage battery cells connected in series is connected in parallel in a plurality of series, and
    A discharger for each series capable of controlling the current value of each discharge current supplied to the load from each of the storage battery units of the plurality of series;
    Based on the result of measuring the charging status of each of the storage battery units of the plurality of series, the discharger for each series connected to the storage battery unit is controlled to control the current value of the discharge current from the storage battery unit. A control circuit;
    A power supply system comprising at least
    The control circuit calculates the difference between the charging statuses of the two battery storage units adjacent to each other with respect to the charging status of each of the plurality of battery storage units, and the difference is equal to or less than a preset charging status threshold value. In the case where the two-series storage battery units are connected, the discharge devices for each of the series connected to the two-series storage battery units are controlled, and the current values of the discharge currents from the two-series storage battery units are controlled to be equal. And power system.
  2.   2. The power supply system according to claim 1, wherein the control circuit measures a storage battery voltage of each of the plurality of storage battery units as the charging state, and calculates a difference between storage battery voltages of two adjacent storage battery units. Then, when the difference is equal to or less than the storage battery voltage threshold set in advance as the charging state threshold, the discharger for each of the series connected to the two series of storage battery units is controlled, and the 2 A power supply system that controls a current value of a discharge current from a storage battery unit of a series to an equal value.
  3.   2. The power supply system according to claim 1, wherein the control circuit measures an SOC (State of Charge) of each of the plurality of series of storage battery units as the state of charge, and between the SOCs of the two series of storage battery units adjacent to each other. When the difference is calculated and the difference is equal to or lower than the SOC threshold set in advance as the charging state threshold, the discharger for each of the series connected to the two series of storage battery units is controlled, A power supply system that controls the current value of the discharge current from the two series of storage battery units to be equal.
  4.   The power supply system according to any one of claims 1 to 3, wherein when the difference between the charging statuses of two series of storage battery units adjacent to each other is equal to or less than the charging status threshold value, An equal value controlled as a current value of a discharge current is a current value of a maximum discharge current that can be output by both of the two battery storage units.
  5. A series of storage battery units formed by connecting a plurality of storage battery cells in series, a plurality of series connected in parallel, and a series connected to each of the plurality of series storage battery units based on the results of measuring the charging status of each of the plurality of series storage battery units A discharge control method for a power supply system that controls each discharger to control a current value of a discharge current supplied to a load from each of the plurality of storage battery units,
    Regarding the charging status of each of the plurality of storage battery units, a difference between the charging statuses of two adjacent storage battery units is calculated, and the difference is equal to or less than a preset charging status threshold. A discharge control method characterized by controlling the discharge devices for each of the series connected to the two series of storage battery units to control the current values of the discharge currents from the two series of storage battery units to be equal to each other. .
  6.   The discharge control method according to claim 5, wherein the storage battery voltage of each of the plurality of storage battery units is measured as the charging state, and a difference between storage battery voltages of two adjacent storage battery units is calculated, When the difference is less than or equal to the storage battery voltage threshold set in advance as the charging status threshold, the two series of storage battery units are controlled by controlling the dischargers for each of the series connected to the two series of storage battery units. The discharge control method characterized by controlling the current value of the discharge current from to equal value.
  7.   6. The discharge control method according to claim 5, wherein a SOC (State of Charge) of each of the plurality of storage battery units is measured as the state of charge, and a difference between the SOCs of the two storage battery units adjacent to each other is calculated. Then, when the difference is equal to or less than the SOC threshold value set in advance as the charging state threshold value, the two series of dischargers connected to the two series of storage battery units are controlled. The discharge control method characterized by controlling the electric current value of the discharge current from the storage battery unit to equal value.
  8.   8. The discharge control method according to claim 5, wherein a difference between the charging states of two adjacent storage battery units adjacent to each other is equal to or less than the charging condition threshold value. The discharge control method characterized in that the equal value controlled as the current value of the discharge current from is the current value of the maximum discharge current that can be output by both of the two battery storage units.
  9.   9. A discharge control program, wherein the discharge control method according to claim 5 is implemented as a program executable by a computer.
JP2010054175A 2010-03-11 2010-03-11 Power supply system, discharge control method, and discharge control program Expired - Fee Related JP5314626B2 (en)

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