CHARGE / DISTILLATION CONTROL SYSTEM

Abstract

The invention relates to a charge / discharge control system, wherein: in a case where battery modules (4) are to be discharged, when the battery modules are divided into a plurality of battery module groups (4G), the first battery module group being the one with the highest average voltage among the battery module groups, the second battery module group being the one with the second highest average voltage among the battery module groups, the controller activates the second and third switches (42, 8) of the first battery module group, and the controller activates these switches of the second battery module group and deactivates these switches of the first battery module group. Abstract figure: Figure 2

Description

Title of the invention: Charge / discharge control system technical field

[0001] This disclosure relates to a charge / discharge control system. Previous technique

[0002] Document JP 2019-208309 A discloses a drive control system for an electric vehicle. In the drive control system of document JP 2019-208309 A, a plurality of battery packs connected in parallel are used simultaneously, resulting in a greater amount of electric current flowing to the load from one of the battery packs with a relatively short cable length to the load than from another battery pack with a relatively long cable length to the load, depending on the difference in cable resistance between the cable lengths. This results in the possibility that the battery packs may have different intrinsic degradation rates depending on a variation in cable length.The drive control system described in document JP 2019-208309 A aims to mitigate such a problem in the drive control system.

[0003] More specifically, in document JP 2019-208309 A, the drive control system comprises a battery control unit, a power supply unit, and an energy capacity acquisition unit. The battery control unit selects one of the battery packs as the drive battery pack. The power supply unit provides electrical energy from the drive battery pack to an electric motor. The power capacity acquisition unit acquires information regarding the energy capacity of the selected battery pack. When the energy capacity of the selected battery pack becomes equal to or less than a given value, the battery control unit of the drive control system selects another of the battery packs as the drive battery pack.

[0004] The above drive control system acts only to switch, for drive, from one of the battery packs to the other when the energy capacity becomes equal to or less than the given value, but is not designed to minimize, given the frequency of use of these, an imbalance in the degree of deterioration among the battery packs.

[0005] The present invention was developed in light of the above problems. One object of the invention is to provide a charge / discharge control system capable of minimize an imbalance in the frequency of use among the battery modules and reduce an imbalance in the degree of deterioration among the battery modules.

[0006] According to one aspect of the invention, a charge / discharge control system is proposed comprising: a power generation unit; an electrical load; a plurality of battery modules; a first connection path through which the battery modules are connected in parallel to each other; a first switch which is disposed among the first connection path, the power generation unit and the electrical load and switchable between a conducting state in which the first connection path is connected to the power generation unit or to the electrical load, and a blocking state in which the first connection path is disconnected from the power generation unit and the electrical load; and a controller which is supplied with electrical power by the power generation unit or the battery modules, in which each of the battery modules comprises a battery,a second switch that can be switched between a conducting state in which the battery is connected to the first connection path and a blocking state in which the battery is disconnected from the first connection path, and a battery management device that controls a battery state and a switching operation of the second switch, a third switch is disposed between each of the battery management devices and the first connection path, the third switch being switchable between a conducting state in which the battery management device is connected to the first connection path and a blocking state in which the battery management device is disconnected from the first connection path, the controller can control the switching operations of the first switch and the third switches,and in a case where the first switch is placed in the conducting state in which the first connection path is connected to the electrical load in order to discharge the battery modules: when the battery modules are divided into a plurality of battery module groups, each comprising at least one of the battery modules, a first of the battery module groups having the highest average voltage among the battery module groups,a second group of battery modules being the second highest average voltage among the battery module groups; the controller activates the second and third switches of each battery module in the first group of battery modules; and the controller activates the second and third switches of each battery module in the second group of battery modules and deactivates the second and third switches of each battery module in the first group of battery modules, provided that a first average voltage level, which is the average voltage at the first level, group of battery modules, becomes less than a second average voltage level, which is the average voltage at the level of the second group of battery modules, and that a difference between the first average voltage level and the second average voltage level becomes greater than a first given value.

[0007] According to the present invention, it is possible to propose a charge / discharge control system capable of minimizing an imbalance in the frequency of use among the battery modules and reducing an imbalance in the degree of deterioration among the battery modules.

[0008] In one embodiment, the battery modules are, in order from highest voltage level to lowest voltage level, divided to form battery module groups, each battery module group not comprising two or more battery modules between which the voltage levels at its batteries differ by more than a second given value.

[0009] In one embodiment, the first average voltage level is lower than the second average voltage level, and a time interval from the start of the discharge of the first group of battery modules until a difference between the first average voltage level and the second average voltage level becomes greater than the first given value is shorter than a given duration, the controller prevents the first group of battery modules from being charged or discharged.

[0010] In one embodiment, when the battery modules are divided into groups of battery modules, with two or more of the battery module groups each having the highest average voltage among the battery module groups, the controller selects the one of the two or more battery module groups that has the lowest total number of discharges as the first battery module group, and when a total amount of electrical energy discharged from each of the batteries reaches 100%, which is equivalent to a full capacity of the corresponding battery, the controller increments the number of discharge occurrences by one.

[0011] In one embodiment, the controller estimates the total amount of electrical energy discharged from each of the batteries by means of a map representing a correlation between a battery discharge capacity, a battery temperature, and a battery voltage level.

[0012] In one embodiment, the power generation unit is a power generator that generates electricity by means of renewable energy.

[0013] In one embodiment, the electric charge is a light emitter. Brief description of the drawings

[0014] Other features, details and advantages of the invention will become apparent from reading the detailed description below and from analyzing the accompanying drawings, in which: Fig. 1

[0015] [Fig.1] is a schematic view that illustrates a charge / discharge control system according to one embodiment of the invention; Fig. 2

[0016] [Fig.2] shows graphs that represent voltage level changes at the battery modules of a charge / discharge control system according to an embodiment of the invention; Fig. 3

[0017] [Fig.3] is a flowchart of a sequence of discharge control steps to be carried out by a charge / discharge control system according to an embodiment of the invention; Fig. 4

[0018] [Fig.4] shows how to calculate the number of discharge occurrences of each battery module installed in a charge / discharge control system according to an embodiment of the invention; Fig. 5

[0019] [Fig.5] is a view showing a map representing discharge characteristics of battery modules installed in a charge / discharge control system according to an embodiment of the invention; Fig. 6

[0020] [Fig. 6] is a timing diagram illustrating an example of the operation of a charge / discharge control system according to one embodiment of the invention. Description of embodiments

[0021] A charge / discharge control system according to an embodiment of the invention comprises: a power generation unit; an electrical load; a plurality of battery modules; a first connection path through which the battery modules are connected in parallel with each other; a first switch disposed among the first connection path, the power generation unit, and the electrical load, and switchable between a conducting state in which the first connection path is connected to the power generation unit or the electrical load, and a blocking state in which the first connection path is disconnected from the power generation unit and the electrical load; and a controller supplied with electrical power by the power generation unit or the battery modules, wherein each of the battery modules comprises a battery, a second switch that can be switched between a conducting state in which the battery is connected to the first connection path and a blocking state in which the battery is disconnected from the first connection path, and a battery management device that controls a battery state and a switching operation of the second switch, a third switch is disposed between each of the battery management devices and the first connection path, the third switch being switchable between a conducting state in which the battery management device is connected to the first connection path and a blocking state in which the battery management device is disconnected from the first connection path, the controller can control the switching operations of the first switch and the third switches,and in a case where the first switch is placed in the conducting state in which the first connection path is connected to the electrical load in order to discharge the battery modules: when the battery modules are divided into a plurality of battery module groups, each comprising at least one of the battery modules, a first of the battery module groups having the highest average voltage among the battery module groups,a second group of battery modules being the second highest average voltage among the battery module groups; the controller activates the second and third switches of each battery module in the first group of battery modules; and the controller activates the second and third switches of each battery module in the second group of battery modules and deactivates the second and third switches of each battery module in the first group of battery modules, provided that a first average voltage level, which is the average voltage at the level of the first group of battery modules, becomes lower than a second average voltage level, which is the average voltage at the level of the second group of battery modules, and that a difference between the first average voltage level and the second average voltage level becomes greater than a given first value.

[0022] A charge / discharge control system according to an embodiment of the present invention is described below with reference to the drawings.

[0023] The charge / discharge control system 1 according to this embodiment, as illustrated in [Fig.1], comprises a power generation unit 2, an electrical load 3, a plurality of battery modules 4, a first connection path 5, a first switch 6, and a controller 7.

[0024] The charge / discharge control system 1 is equipped with n battery modules 4. More specifically, the n battery modules 4 comprise battery modules 4a to 4n. In the following description, each of the battery modules 4a to 4n is also simply referred to as battery module 4 unless differentiated from the others.

[0025] The power generation unit 2 is a power generator, such as a solar photovoltaic unit or a wind power generator, that generates electricity using renewable energy. The power generation unit 2 may be a hydroelectric generator, a geothermal power generator, or a biomass power generator, that generates electricity using renewable energy.

[0026] The electrical load 3 includes an electrical device equipped with a light emitter, such as a light or an electronic display panel, but is not limited to the electrical device.

[0027] The battery modules 4a to 4n are connected in parallel to each other, with the first connection path 5. Each battery module 4 includes a battery 41, a second switch 42 and a battery management device 43.

[0028] In order to identify the batteries 41, the second switches 42, and the battery management devices 43 among the battery modules 4a to 4n, in the following description, the batteries 41, the second switches 42, and the battery management devices 43 shall also be designated by numbers followed by the alphabetical suffixes "a" to "n," corresponding to the respective battery modules 4a to 4n. In addition to the battery modules 4, each battery, each second switch, and each battery management device shall also be simply referred to as battery 41, second switch 42, and battery management device 43, unless otherwise specified.

[0029] Each of the batteries 41 is a rechargeable / dischargeable secondary battery, such as a lithium-ion battery. Lithium-ion batteries fitted and used in a vehicle can be reused as 4L batteries

[0030] Each of the second switches 42 is configured to toggle between a conducting state in which the battery 41 and the first connection path 5 are connected to each other and a blocking state in which they are disconnected from each other. Each of the second switches 42 is controlled by one of the corresponding battery management devices 43, so as to toggle between the conducting and blocking states of the second switch 42.

[0031] Each of the battery management devices 43 is designed to monitor and control the state of one of the corresponding batteries 41, such as the voltage level developed at the battery 41 or the amount of electrical energy remaining in the battery 41, for example, its EDC (i.e., "State of Charge," or SOC). More specifically, the battery management device 43 can switch between a conducting state and a blocking state of the second switch 42. The battery management device 43 calculates the EDC of the battery 41 using an amount of current charged into, or discharged from, the battery 41.

[0032] The battery management device 43 is connected to the controller 7 for the delivery of information on, for example, the voltage level developed at the level of the battery 41 and the EDC of the battery 41 to the controller 7.

[0033] The third switch 8 is disposed between each of the battery management devices 43 and the first connection path 5. The third switch 8 is selectively placed in a conducting state to connect or in a blocking state to disconnect the battery management device 43 from the first connection path 5. Each of the battery management devices 43 can be equipped with at least one third switch 8. In this embodiment, each of the battery management devices 43 is equipped with a single third switch 8, but may alternatively include two or more third switches 8.

[0034] In order to identify the third switches 8 among the battery management devices 43a to 43n in the following description, they shall also be designated by numbers followed by the alphabetical suffixes "a" to "n" corresponding to the respective battery management devices 43a to 43n. Each third switch shall also simply be referred to as the third switch 8 unless otherwise specified.

[0035] The switching between the passing state and the blocking state of the third switch 8 is carried out by the controller 7.

[0036] The battery modules 4a to 4n are connected in parallel to each other at the first connection path 5. The first switch 6 is connected to one end of the first connection path 5.

[0037] The first switch 6 is disposed among the first connection path 5, the power generation unit 2 and the electrical load 3 and is selectively placed in a conducting state to connect the first connection path 5 to the power generation unit 2 or to the electrical load 3, or a blocking state to disconnect the first connection path 5 from these.

[0038] In other words, the first switch 6 is selectively placed in an electrically generating passing state to connect the first connection path 5 with the power generating unit 2, an electrically discharging passing state to connect the first connection path 5 with the electrical load 3, or a blocking state to disconnect the first connection path 5 from both the power generating unit 2 and the electrical load 3.

[0039] The switching between the electrical generation on state, the electrical discharge on state, and the blocking state is performed by the controller 7. When the controller 7 is not yet energized, for example, the control system of charge / discharge 1 is off, it is preferable that the first switch 6 be placed in the electrical generation forward state in order to ensure the electrical energy necessary to start the charge / discharge control system 1.

[0040] The controller 7 is implemented by a computer unit composed of a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read-Only Memory), an input port, and an output port. The ROM of the computer unit stores a plurality of constants and programs used to operate the computer as controller 7. In other words, the CPU uses RAM as a workspace to execute the programs stored in ROM, thereby operating the computer unit as controller 7.

[0041] The controller 7 is connected to the first connection path 5 and supplied with electrical energy from the power generation group 2 or from at least one of the battery modules 4a to 4n via the first connection path 5. The controller 7 acts to switch between the on state and the blocking state of the first switch 6 and between the on state and the blocking state of each of the third switches 8.

[0042] The controller 7 has a plurality of sensors 9 connected to it. In this embodiment, the sensors 9 required depending on the type of power generation group 2 and the electrical load 3 are connected to the controller 7. For example, the sensors 9 include sensors such as a wind sensor, a light sensor, and a temperature sensor that are capable of detecting changes in the external environment. In a case where the electrical load 3 is a light, the controller 7 can be equipped with a timer that controls the duration for which the light remains on or the time at which the light should be activated.

[0043] LOAD CONTROL

[0044] A load control task performed by the load / discharge control system 1 is described below.

[0045] When it is necessary to discharge at least one of the n battery modules 4, the controller 7 divides the n battery modules 4 into a plurality of battery module groups 4G, each of which includes at least one of the battery modules 4.

[0046] More specifically, the controller 7 divides the n battery modules 4 into groups of 4G battery modules in order from the highest voltage level to the lowest voltage level of the battery modules 4, each of which comprises at least one of the battery modules 4. In other words, the n battery modules 4 are selected in order from the highest voltage level to the lowest voltage level to constitute the respective 4G battery module groups.

[0047] For example, if there are eight battery modules 4 with different voltage levels, the battery modules 4 are classified into first, second, third, and fourth groups of battery modules 4G. The first group of battery modules 4G comprises two battery modules 4 developing voltages that are the highest and second highest voltages among the battery modules 4. The second group of battery modules 4G comprises two battery modules 4 developing voltages that are the third and fourth highest voltages among the battery modules 4. The third group of battery modules 4G comprises two battery modules 4 developing voltages that are the fifth and sixth highest voltages among the battery modules 4.The fourth group of 4G battery modules comprises two 4 battery modules developing voltages that are the seventh and eighth highest voltages among the 4 battery modules.

[0048] The reason why it is not a single battery module but groups of battery modules composed of battery modules that are used in the system is that, if the single battery module 4 were used in the system to discharge electrical energy, a failure of it during electrical energy discharge, resulting from any factor other than that leading to a voltage drop below a discharge activation voltage level, could lead to a failure in the supply of electrical power to the controller 7, leading to a malfunction of the discharge / charge control system 1. It is therefore desirable that the 4G groups of battery modules composed of battery modules 4 be used to discharge electrical energy.

[0049] However, it is preferable that each of the 4G battery module groups be designed so as not to include two or more battery modules 4 whose voltage level difference is greater than a given value Ath (second given value), that is to say, two or more battery modules 4 between which the voltage levels differ by more than a given value Ath should not belong to the same 4G battery module group. For example, in the case where a voltage level difference between the two battery modules 4 that have the highest and second highest voltage levels is greater than the given value Ath, the first 4G battery module group consists only of the module with the highest battery 4.In such a case, if a voltage level difference between two battery modules 4 that are the second and third highest in voltage levels among the battery modules 4 is less than or equal to the given value Ath, the second group of 4G battery modules is made up of said two battery modules 4. That is to say, in the case where there exist groups of 4G battery modules each comprising battery modules 4, a level difference of . voltage between battery modules 4 in each group of 4G battery modules is equal to or less than the given value Ath.

[0050] The reason why it is intended that none of the 4G battery module groups may include two of the battery modules 4 between which the voltage level difference is greater than the given value Ath is that when a part of the battery modules 4 in each of the battery module groups 4G develops an undesirably high voltage, a large amount of electric current may be caused to flow between the battery modules 4 in each group of 4G battery modules due to the large voltage difference between them, resulting in a malfunction of an electrical circuit of the charge / discharge control system 1.

[0051] Accordingly, the respective 4G battery module groups consist of the battery modules 4 in order from highest to lowest voltage level, each 4G battery module group comprising at least one battery module 4 but not two or more of the battery modules 4 whose voltage level difference between them is less than or equal to the given value Ath.

[0052] The controller 7 selects two of the 4G battery module groups that have the highest and second-highest average voltages of the battery modules 4 among the 4G battery module groups, and defines them as the first 4G1 battery module and the second 4G2 battery module. More specifically, one of the 4G battery module groups that has the highest average voltage (also referred to below as the average voltage) developed at its batteries 41 among the 4G battery module groups is defined as the first 4G1 battery module group. Another of the 4G battery module groups that has the second-highest average voltage developed at its batteries 41 among the 4G battery module groups is defined as the second 4G2 battery module group.Here, in a case where a 4G battery module group consists of a battery module 4, the average voltage of the latter corresponds to the voltage level in said battery module 4.

[0053] The controller 7 activates the second switch 42 of the battery module(s) 4 constituting the first group of battery modules 4G1, and the third switch 8 located between said battery module 4 and the first connection path 5 (hereinafter these switches 42, 8 are also referred to as the second switch 42 and third switch 8 of the battery module 4).

[0054] When a first average voltage level BMV1, which is an average of the voltages developed at the batteries 41 of the first group of battery modules 4G1, is lower than a second average voltage level BMV2, which is an average of the voltages developed at the batteries 41 of the second group of 4G2 battery modules, and that a difference between the first average voltage level BMV1 and the second average voltage level BMV2 is greater than a given value Vth (first given value), the controller 7 activates the second switch 42 and the third switch 8 of each battery module 4 of the second group of 4G2 battery modules and also deactivates the second switch 42 and the third switch 8 of each battery module 4 of the first group of 4G1 battery modules.

[0055] The given value Vth is a voltage range within which a voltage drop which occurs at the level of the battery modules 4 immediately after the battery modules 4 are connected to the electrical load 3 does not cause the frequency switching of one to the other of the groups of battery modules 4G, and which is experimentally obtained and stored in the ROM of the controller 7 in advance.

[0056] The use of the given value Vth prevents the second switches 42 and the third switches 8 from being activated unnecessarily, and also reduces a variation in voltage applied to the electrical load 3 or in electrical current flowing to the electrical load 3, both resulting from the activation or deactivation operations of the second switches 42 and the third switches 8.

[0057] Typically, the discharge rate of the 4G battery module groups differs between the moment when the first switch 6 is in the conducting state for electrical discharge and the moment when the first switch 6 is in the blocking state. The given value Vth can therefore be modified between the moment when the first switch 6 is in the conducting state for electrical discharge and the moment when the first switch 6 is in the blocking state.

[0058] A discharge operation of the charge / discharge control system 1 equipped, for example, with the four groups of 4G battery modules is described below with reference to [Fig.2](a) to 2(e).

[0059] The bars arranged on a horizontal axis in the bar graphs illustrated in [Fig. 2] represent the average voltages developed at the level of the 4G battery module groups. A bar, as designated by "1", shows the average voltage of the first 4G1 battery module group. A bar, as designated by "2", shows the average voltage of the second 4G2 battery module group.

[0060] Each vertical axis of [Fig.2] represents a level of the average voltage of each of the 4G battery module groups. Each interval between the dashed lines on the vertical axis represents the given value Vth described above.

[0061] Fig. 2 shows the change in average voltage of each of two groups of 4G battery modules, i.e. the first group of 4G1 battery modules and the second group of 4G2 battery modules, which results from their discharge.

[0062] First, the controller 7, as shown in [Fig. 2](a), defines one of the 4G battery module groups with the highest average voltage as the first 4G battery module group, 4G1, and another of the 4G battery module groups with the second highest average voltage as the second 4G battery module group, 4G2. In the following discussion, the average voltage at the first 4G battery module group is, as described above, referred to as the first average voltage level, BMV1. The average voltage at the second 4G battery module group is referred to as the second average voltage level, BMV2.

[0063] The controller 7 then activates the second switch 42 and the third switch 8 of each battery module 4 of the first group of battery modules 4G1 to begin discharging electrical energy from them.

[0064] Then, when the first average voltage level BMV1 falls below the second average voltage level BMV2 due to the discharge of the first group of battery modules 4G1, and a difference between the first average voltage level BMV1 and the second average voltage level BMV2 exceeds the given value Vth, the controller 7, as illustrated in [Fig.2](b), updates the first group of battery modules 4G1 and the second group of battery modules 4G2. In the illustrated example, the 4G battery module group designated by "2" in [Fig.2](a) initially selected as the second 4G2 battery module group is updated as the first 4G1 battery module group (which is designated by "1" in [Fig.2](b)), while the 4G battery module group initially selected as the first 4G1 battery module group is updated as the second 4G2 battery module group.

[0065] Subsequently, when the first average voltage level BMV1 falls below the second average voltage level BMV2 due to the discharge of the first group of battery modules 4G1, and the difference between the first average voltage level BMV1 and the second average voltage level BMV2 exceeds the given value Vth, the controller 7, as shown in [Fig. 2](c), re-defines the previously selected group of 4G battery modules as the second group of battery modules 4G2 as the first group of battery modules 4G1, and also re-defines the previously selected group of battery modules 4G1 as the second group of battery modules 4G2. The same applies to [Fig. 2](d) and [Fig. 2](e).In this way, the first group of 4G1 battery modules and the second group of 4G2 battery modules are re-selected to continue discharging electrical energy from the 4G battery module groups.

[0066] A sequence of discharge operations to be carried out by the charge / discharge control system 1 is described below with reference to the flowchart of [Fig.3].

[0067] The discharge operations illustrated in [Fig.3] are mainly executed by the controller 7 and the battery management device 43. The discharge control program is executed cyclically at given intervals.

[0068] After entering the discharge control program, the routine proceeds to the SI step in which the controller 7 determines whether there is a request to actuation the electrical load 3. More specifically, the controller 7 determines whether a request to actuation the electrical load 3 should be submitted based on an external factor. For example, when the ambient light level, measured by the light sensor, falls below a reference level that requires the light (i.e., the electrical load 3) to be activated, or when a defined time is reached at which the light (i.e., the electrical load 3) must be activated, the controller 7 submits the request to the electrical load 3 to actuation. Alternatively, the controller 7 can determine whether the request should be submitted to the electrical load 3 based on the presence or absence of pedestrians or vehicles detected by the sensors 9.

[0069] If a NO response is obtained in the IF step, meaning that there is no request to actuation the electrical load 3, then the routine proceeds to step S3 in which the controller 7 places the first switch 6 in the blocking state. The routine then proceeds to step S5. This prevents unwanted or excessive discharge of the battery modules 4.

[0070] Alternatively, if a YES response is obtained at the IF step meaning that the demand to actuation the electrical load 3 exists, then the routine proceeds to the S2 step in which the controller 7 determines whether there is one or more battery module(s) 4 which develop(s) a voltage greater than or equal to the discharge activation voltage level.

[0071] The controller 7 determines which battery module(s) 4 equipped with the battery 41 develop a voltage that is greater than or equal to the discharge activation voltage level as a dischargeable battery module. The controller 7 can determine which battery module(s) 4 equipped with the battery 41 have an EDC greater than or equal to a given EDC that can be discharged as a dischargeable battery module(s).

[0072] The discharge activation voltage level is a voltage level that is developed at each of the battery modules 4 and is high enough to keep the controller 7 actuated for a given time in the absence of power to the power generation unit 2. The given time is an interval The expected time interval before a subsequent charging cycle begins can be adjusted based on output data from sensors 9 or alternatively set to a predetermined, experimentally obtained constant value. Typically, the amount of sunshine or the number of rainy or sunny days per year varies depending on the area where the charge / discharge control system 1 is installed. Therefore, the expected time interval is adjusted according to the installation area of ​​the charge / discharge control system 1. The discharge activation voltage level can also be adjusted according to the installation area of ​​the charge / discharge control system 1.

[0073] If a NO response is obtained at step S2, meaning that there is no battery module 4 developing voltages greater than or equal to the discharge activation voltage level, then the routine proceeds to step S3 in which the controller 7 places the first switch 6 in the blocking state. The routine then proceeds to step S5. This prevents over-discharging of the battery modules 4.

[0074] Alternatively, if a YES response is obtained in step S2, meaning that there is one or more battery module(s) 4 developing a voltage greater than or equal to the discharge activation voltage level, then the routine proceeds to step S4 where the controller 7 places the first switch 6 in the electrical discharge on state. For example, in repeated operations, in a case where the first switch 6 is already in the electrical discharge on state, the electrical discharge on state is maintained in step S4.

[0075] Next, the routine proceeds to step S5 where the controller 7 defines the 4G battery module groups, each of which, as described above, includes at least one of the battery modules 4. More specifically, the controller 7 divides the n battery modules 4 into a plurality of 4G battery module groups, each of which includes at least one of the battery modules 4.

[0076] The routine proceeds to step S6 in which the controller 7, as described above, determines one of the 4G battery module groups that has the highest average voltage among the 4G battery module groups as the first 4G1 battery module group. The controller 7 also determines another of the 4G battery module groups that has the second highest average voltage among the 4G2 battery module groups as the second 4G1 battery module group.

[0077] The routine proceeds to step S7 in which the controller 7 activates the second switch 42 and the third switch 8 of each battery module 4 of the first group of battery modules 4G1. This causes the first group of battery modules 4G1 to begin discharging electrical energy.

[0078] The routine proceeds to step S8 in which the controller 7 disables the second switches 42 and the third switches 8 of all battery modules 4 of the other 4G battery module groups than the first 4G1 battery module group. This causes only the first 4G1 battery module group, which has the highest average voltage, to discharge electrical energy; in other words, it prevents the other 4G battery module groups from discharging.

[0079] The routine then proceeds to step S9 in which the controller 7 determines whether the first average voltage level BMV1 of the first group of battery modules 4G1 is greater than an average discharge activation voltage level.

[0080] The average discharge activation voltage level is, like the discharge activation voltage level, a voltage level that is developed by each of the battery modules 4 and high enough to keep the controller 7 operated for a given time in the absence of power from the power generation unit 2. The given time is a time interval that is expected to elapse before a subsequent charging cycle begins.

[0081] It is desirable that the average discharge activation voltage level be set as a voltage threshold higher than the discharge activation voltage level. This is because when battery modules 4 with different voltage levels are connected together, the voltage levels will equalize over time, but a considerable amount of time is required to equalize the voltage levels when the connection time during which the battery modules 4 are connected together is short or when the number of battery modules 4 constituting the battery module group 4G is large.To prevent each of the 4 battery modules in the 4G battery module group from developing a voltage lower than the discharge activation voltage level during the above time period due to the voltage values ​​of the respective 4 battery modules, the average discharge activation voltage level is preferably set higher than the discharge activation voltage level. This prevents the 4 battery modules with the lowest voltage level in each of the 4G battery module groups from excessively discharging.

[0082] The operations of steps S6 and S9 serve to minimize a difference in the degree of deterioration of the battery modules 4 which results from a difference in the frequency of use of the battery modules 4 constituting one of the groups of 4G battery modules.

[0083] If a NO response is obtained at step S9, meaning that the first average voltage level BMV 1 is less than or equal to the average discharge activation voltage level, then the routine terminates.

[0084] Alternatively, if a YES response is obtained at step S9, meaning that the first average voltage level BMV1 is greater than the discharge activation average voltage level, then the routine proceeds to step S10 where the controller 7 determines whether a value obtained by subtracting the first average voltage level BMV1 from the second average voltage level BMV2 is greater than the given value Vth.

[0085] The given value Vth is set to a positive value in this embodiment. This allows the controller 7 to determine in step S10 whether the first average voltage level BMV1 is less than the second average voltage level BMV2, and whether the difference between the first average voltage level BMV1 and the second average voltage level BMV2 is greater than the given value Vth.

[0086] If a NO response is obtained at step S10 meaning that the value obtained by subtracting the first average voltage level BMV 1 from the second average voltage level BMV2 is less than or equal to the given value Vth, then the routine returns to step S9.

[0087] Alternatively, if a YES response is obtained at step S10 meaning that the value obtained by subtracting the first average voltage level BMV1 from the second average voltage level BMV2 is greater than the given value Vth, then the routine terminates.

[0088] Consequently, in a subsequent charge / discharge control cycle, the second switch 42 and the third switch 8 of each battery module 4 in the second group of 4G2 battery modules are activated, while the second switch 42 and the third switch 8 of each battery module 4 in the first group of 4G1 battery modules are deactivated. This is because, in the subsequent charge / discharge control cycle, the second group of 4G2 battery modules from the previous cycle must be treated as one of the 4G battery module groups (i.e., the first group of 4G1 battery modules) with the highest average voltage among the 4G battery module groups.

[0089] When the time interval from the start of charging at step S7 until the value obtained by subtracting the first average voltage level BMV1 from the second average voltage level BMV2 is determined at step S10 to be greater than the given value Vth is shorter than a given duration, the controller 7 can determine that at least one of the batteries 41 in the battery modules 4 of the first battery module group 4G1 is too old. This is because the aging of the batteries 41 results in an increase in the rate at which the voltage thus developed falls (i.e., an increase in the amplitude with which the voltage falls per unit of time). The given duration is set to a lower limit of a time range during which it is possible to diagnose that The 41 batteries are not yet too old, which is experimentally obtained and stored in advance in the ROM of controller 7.

[0090] When it is determined in the above manner that the battery 41 is too old and that the first average voltage level BMV1 is less than or equal to the average discharge activation voltage level, the controller 7 then prevents the first group of battery modules 4G1 from charging or discharging in order to avoid malfunction or overheating of the first group of battery modules 4G1.

[0091] When it is determined in step S6 that there are two or more groups of battery modules S6, each with the highest average voltage, the controller 7 selects two of said groups of 4G battery modules as the first group of 4G battery modules and the second group of 4G1 battery modules in order from the smallest to the largest total number of discharge occurrences in the battery module(s) 4 of each of said groups of 4G battery modules. In other words, in such a case, one of said groups of 4G battery modules, with the smallest total number, must be treated as the first group of 4G1 battery modules, which has the highest average voltage, and another of said groups of 4G battery modules, with the second smallest total number, must be treated as the second group of 4G2 battery modules, which has the second highest average voltage.The total number is the sum of the number of discharge occurrences in all 4 battery modules of a 4G battery module group.

[0092] More specifically, when, in each of the battery modules 4, a total amount of electrical energy discharged from the battery 41 of them reaches 100%, which is equivalent to a full capacity of said battery 41, the controller 7 increments the number of occurrences of discharges mentioned above.

[0093] For example, when the battery module 4 (which will be called first battery module 4) whose state of charge (EDC) is, as shown in [Fig.4](a), initially 100% discharged, so that its EDC falls to 40%, as illustrated in [Fig.4](b), the amount of electrical energy discharged drops to 60% at that time.

[0094] Next, when the first battery module 4 is, as shown in [Fig. 4](c), charged until its EDC is 80%, and then its EDC drops to 40%, the amount of electrical energy discharged reaches 40% at that point. Consequently, the total amount of electrical energy discharged from the first battery module 4 becomes 60% plus 40% (= 100%), which is equivalent to the full capacity of the battery 41 of the corresponding battery module 4 (the first battery module 4). The controller 7 then increments the number of discharges of the battery 41 of the first battery module 4 by one. When such a discharge is repeated, the controller 7 increments the number of occurrences of discharges in this manner. In [Fig.4], "state of charge" indicates a quantity of charge as a percentage (%).

[0095] The controller 7 can estimate a discharged quantity of the battery 41 using a map, as illustrated in [Fig.5], representing a correlation between a discharge capacity of the battery 41, the temperature of the battery 41 and the voltage level developed at the battery 41. The map of [Fig.5] is obtained experimentally and stored in the ROM of the controller 7 in advance.

[0096] An example of the operation of the charge / discharge control system 1 in this embodiment is described below with reference to [Fig. 6]. [Fig. 6] shows the battery modules 4a, 4b and 4n for convenience.

[0097] In the example illustrated in [Fig.6], each of the battery modules 4a, 4b and 4n constitutes a group of 4G battery modules. In other words, the battery modules 4a, 4b and 4n are divided into three groups of 4G battery modules, each of the groups of 4G battery modules comprising only one of the battery modules 4a, 4b, 4n.

[0098] At time t0, there is no demand to actuation the electrical load 3. The first switch 6 is thus placed in the blocking state. In this case, among the battery modules 4a, 4b and 4n, battery module 4a is defined as the first group of battery modules 4G1 representing the highest average voltage, and battery module 4b is defined as the second group of battery modules 4G2 representing the second highest average voltage.

[0099] The second switch 42 and the third switch 8 of battery module 4a are therefore activated. The second switches 42 and the third switches 8 of battery modules 4 other than battery module 4a are kept in the blocking position. Thus, at time t0, the charge / discharge control system 1 is powered solely by battery module 4a.

[0100] Then, at time tl, when a value obtained by subtracting the voltage level at the level of battery module 4a from that at the level of battery module 4b, in other words, a value obtained by subtracting the first average voltage level BMV1 from the second average voltage level BMV2, becomes greater than the given value Vth, the controller 7 updates the first and second groups of battery modules 4G1 and 4G2 defined at time tO.

[0101] More precisely, at time t1, battery module 4b is newly defined as the first group of 4G1 battery modules. Battery module 4n is newly defined as the second group of 4G2 battery modules. The second switch 42 and the third switch 8 of battery module 4b, as the newly defined first group of 4G1 battery modules, are therefore activated. The second switches 42 and the third switches 8 of the battery modules 4 other than battery module 4b are cut / held blocking.

[0102] At time t2, when a value obtained by subtracting the voltage level at the level of battery module 4b from that at the level of battery module 4n, in other words, a value obtained by subtracting the first average voltage level BMV1 from the second average voltage level BMV2, becomes greater than the given value Vth, the controller 7 updates again the first and second groups of battery modules 4G1 and 4G2 defined at time tl.

[0103] More precisely, at time t2, battery module 4n is newly defined as the first group of 4G1 battery modules. Battery module 4a is newly defined as the second group of 4G2 battery modules. The second switch 42 and the third switch 8 of battery module 4n, as the newly defined first group of 4G1 battery modules, are therefore activated. The second switches 42 and the third switches 8 of battery modules 4 other than battery module 4n are closed / held closed.

[0104] Then, at time t3, when a request to activate the electrical load 3 is made, the first switch 6 is placed in the conducting state for electrical discharge because there are battery modules 4 whose voltage levels are each greater than or equal to a discharge activation voltage level. The battery module 4n remains unchanged as the first group of battery modules 4G1 and thus serves to distribute electrical energy to the electrical load 3.

[0105] The demand continues to be issued to operate the electrical load 3 until time t4. The first group of battery modules 4G1 is therefore updated cyclically in the aforementioned manner to continue discharging the first group of battery modules 4G1 until the voltage levels of all the battery modules 4 are each below the discharge activation voltage level.

[0106] At time t4, when the voltage levels at all battery modules 4 are each below the discharge activation voltage level, the controller 7 cuts off the first switch 6, whether or not there is a demand to actuation the electrical load 3. This also causes the electrical load 3 to be deactivated. At this time, battery module 4b is the first group of battery modules 4G1, and battery module 4n is the second group of battery modules 4G2.

[0107] Then, at time t5 when a value obtained by subtracting the voltage level developed at the level of battery module 4b from that at the level of battery module 4n becomes greater than the given value Vth, the controller 7 again updates the first group of battery modules 4G1 and the second group of battery modules 4G2.

[0108] More precisely, at time t5, battery module 4n is newly defined as the first group of battery modules 4G1. Battery module 4a is newly defined as the second group of battery modules 4G2. The second switch 42 and the third switch 8 of battery module 4n are therefore activated. The second switches 42 and the third switches 8 for battery modules 4 other than battery module 4n are closed / held closed.

[0109] Next, the first group of battery modules 4G1 is updated cyclically in the aforementioned manner based on the comparison of a value obtained by subtracting the first average voltage level BMV1 from the second average voltage level BMV2 and the given value Vth up to time t6.

[0110] Then, at time t6, when the voltage generated by the power generation unit 2 rises to a chargeable voltage level that allows the battery modules 4 to be charged, the controller 7 places the first switch 6 in the power generation conducting state and activates the second switches 42 and the third switches 8 of the battery modules 4b and 4n, which are at a low voltage level. This initiates the charging of the battery modules 4b and 4n.

[0111] Then, at time t7, when the voltage levels at the battery modules 4b and 4n become equal to that of the battery module 4a, the controller 7 activates the second switch 42 and the third switch 8 of the battery module 4a, thus also starting the charging of the battery module 4a.

[0112] As can be seen from the above description, the charge / discharge control system 1 acts to activate the second switches 42 and the third switches 8 of the battery modules 4 of the second group of battery modules 4G2 and to also deactivate the second switches 42 and the third switch 8 of the battery modules 4 of the first group of battery modules 4G1 on the condition that the first average voltage level BMV1 at the level of the first group of battery modules 4G1 is less than the second average voltage level BMV2 at the level of the second group of battery modules 4G2, and that a difference between the first average voltage level BMV1 and the second average voltage level BMV2 is greater than the given value Vth.

[0113] With the operation described above, the charge / discharge control system 1 first discharges the first group of 4G1 battery modules, which has the highest average voltage among the 4G battery module groups, and then switches to one of the 4G battery module groups, so that it is subsequently discharged from the first group of 4G1 battery modules to the second group of 4G2 battery modules, when the first average voltage level BMV 1 falls to become lower than the given value Vth than that of the second group of 4G2 battery modules which is the second highest in average voltage.

[0114] The charge / discharge control system 1 thus serves to minimize a voltage difference between the groups of 4G battery modules to be discharged, and to avoid a large amount of electrical current between them, by eliminating an imbalance in the usage frequency among the groups of 4G battery modules. This minimizes an imbalance in the usage frequency between the battery modules and reduces an imbalance in the degree of deterioration between the battery modules 4.

[0115] When the electrical load 3 is designed to be operated with a large amount of energy, the charge / discharge control system 1 is capable of distributing electrical energy by means of two or more of the battery modules 4. When operating the electrical load 3 using the 4G battery module groups, each comprising two or more battery modules 4, even if some of the battery modules 4 in the 4G battery module group fail to provide power, the charge / discharge control system 1 is capable of supplying energy from the remaining battery modules 4 to the electrical load 3, thus resulting in improved durability of the charge / discharge control system 1.

[0116] The charge / discharge control system 1 is equipped with battery module groups 4G in which the battery modules 4 are divided in order from highest to lowest in voltage developed at the level of the batteries 4L. Each of the battery module groups 4G is configured so as not to include two or more battery modules 4 between which the voltage levels developed at the level of the batteries 41 are different by more than the given value Ath, each battery module group 4G comprising at least one battery module 4.

[0117] The above classification of the 4G battery module groups in the charge / discharge control system 1, therefore avoids the appearance of a significant difference in voltage level between the battery modules 4 of each of the 4G battery module groups, thus avoiding the appearance of a malfunction of the circuit installed in the charge / discharge control system 1 which would be due to a large amount of electrical current flowing between the battery modules 4.

[0118] When a time interval from the start of the discharge of the first group of 4G1 battery modules until a value, such as obtained by subtracting the first average voltage level BMV1 from the second average voltage level BMV2, is determined to be greater than the given value Vth is shorter than a given duration, the charge / discharge control system 1 prevents the first group of 4G1 battery modules from being charged or discharged.

[0119] The charge / discharge control system 1 is therefore capable of diagnosing the deterioration of the battery modules 4, even when the management device battery 43 is not used continuously and thus causes a failure in the calculation of the EDC of battery 42 using a total amount of discharged or charged electrical current.

[0120] When it is determined that at least one of the batteries 41 of the battery modules 4 of the first group of battery modules 4G1 is undesirably deteriorated, the charge / discharge control system 1, as described above, prevents the first group of battery modules 4G1 from being charged or discharged, thus preventing the battery modules 4 from overheating or breaking due to overcharging or over-discharging them.

[0121] When it is determined that there are two or more groups of 4G battery modules, each with the highest average voltage, the charge / discharge control system 1, as described above, selects two of these groups of 4G battery modules as the first group of 4G1 battery modules and the second group of 4G2 battery modules, in order from the smallest to the largest total number of discharge occurrences in each of their battery modules 4. When the total amount of electrical energy discharged from each of the batteries 41 in each of the battery modules 4 reaches 100%, which is equivalent to the full capacity of the corresponding battery 41, the charge / discharge control system 1 increments the aforementioned number of discharge occurrences by one.

[0122] In other words, when groups of 4G battery modules have the same average voltage level, the charge / discharge control system 1 acts to discharge first the group of these 4G battery modules with the lower discharge frequency. This reduces an imbalance in the degree of deterioration among the groups of 4G battery modules resulting from their frequency of use, thus preventing the battery modules 4 of the 4G battery module groups from needing to be replaced with new ones.

[0123] The charge / discharge control system 1 calculates an actual amount discharged from each of the batteries 41 using the card, as illustrated in [Fig.5], representing a correlation between the discharge capacity of battery 41, the temperature of battery 41 and the voltage developed at the level of battery 4L. This facilitates the simplicity with which the discharge capacity is obtained using the temperature and voltage level.

[0124] The charge / discharge control system 1, as described above, includes the power generation unit 2, which operates to generate electricity using renewable energy. This allows the charge / discharge control system 1 to be installed outdoors independently.

[0125] The charge / discharge control system 1 is designed for the electrical charge 3 implemented by a light emitter, thus enabling the control system charge / discharge 1 to be used for independently installed outdoor electronic lights or display panels.

[0126] Although the present invention has been described in terms of the preferred embodiment for ease of understanding, it should be noted that the invention can be implemented in various ways without departing from the principle of the invention. Therefore, the invention should be understood as including all possible equivalents and modifications of the illustrated embodiment that can be implemented without departing from the principle of the invention as stated in the accompanying claims. Reference signs

[0127] - 1: charge / discharge control system - 2: Power generation unit - 3: electrical charge - 4: Battery module - 4G: battery module group - 4G1: first group of battery modules - 4G2: second group of battery modules - 5: first connection path - 6: first switch - 7: controller - 8: third switch - 9: sensors - 41: battery - 42: second switch - 43: Battery management device - BMV1: first level of medium voltage - BMV2: second level of medium voltage - Vth: given value (first given value) - Ath: given value (second given value).

Claims

1. Demands Charge / discharge control system (1) comprising: a power generation unit (2); an electric charge (3); a plurality of battery modules (4); a first connection path (5) with which the battery modules are connected in parallel to each other; a first switch (6) which is disposed among the first connection path, the power generating unit and the electrical load and switchable between a conducting state in which the first connection path is connected to the power generating unit or to the electrical load, and a blocking state in which the first connection path is disconnected from the power generating unit and the electrical load; and a controller (7) which is supplied with electrical energy by the power generation group or battery modules, in which each of the battery modules includes a battery (41), a second switch (42) which can be switched between a passing state in which the battery is connected to the first connection path and a blocking state in which the battery is disconnected from the first connection path, and a battery management device (43) which controls a battery state and a switching operation of the second switch, a third switch (8) is disposed between each of the battery management devices and the first connection path, the third switch being switchable between a passing state in which the battery management device is connected to the first connection path and a blocking state in which the battery management device is disconnected from the first connection path, The controller manages the switching operations of the first switch and the third switches, and in a case where the first switch is placed in the conducting state, in which the first connection path is connected to the electrical load in order to discharge the battery modules: when the battery modules are divided into a plurality of battery module groups (4G), each of which comprises at least

2. one of the battery modules, a first of the battery module groups (4G1) having the highest average voltage among the battery module groups, a second of the battery module groups (4G2) being the second in highest average voltage among the battery module groups; The controller activates the second and third switches of each battery module in the first group of battery modules; and The controller activates the second and third switches of each battery module in the second group of battery modules and deactivates the second and third switches of each battery module in the first group of battery modules, provided that a first average voltage level (BMV1), which is the average voltage at the level of the first group of battery modules, becomes lower than a second average voltage level (BMV2), which is the average voltage at the level of the second group of battery modules, and that a difference between the first average voltage level and the second average voltage level becomes greater than a given first value (Vth), characterized in that when the battery modules are divided into groups of battery modules, two or more of the groups of battery modules each have the highest average voltage among the groups of battery modules,The controller selects the one of the two or more battery module groups with the lowest total number of discharges as the first battery module group, and when the total amount of electrical energy discharged from each battery reaches 100%, which is equivalent to the full capacity of the corresponding battery, the controller increments the number of discharge occurrences by one. A charge / discharge control system according to claim 1, wherein the battery modules are, in order from highest voltage level to lowest voltage level, divided to form battery module groups, each battery module group not comprising two or more battery modules between which the voltage levels at their batteries differ by more than a given second value (Ath).

3. Charge / discharge control system according to claim 1 or 2, wherein when the first average voltage level is less than the second average voltage level, and a time interval from the start of discharge of the first group of battery modules until a difference between the first average voltage level and the second average voltage level becomes greater than the first given value is shorter than a given duration, the controller prevents the first group of battery modules from being charged or discharged.

4. A charge / discharge control system according to claim 1, wherein the controller estimates the total amount of electrical energy discharged from each of the batteries by means of a map representing a correlation between a battery discharge capacity, a battery temperature, and a battery voltage level.

5. Charge / discharge control system according to any one of claims 1 to 4, wherein the power generation unit is a power generator that generates electricity by means of renewable energy.

6. Charge / discharge control system according to any one of claims 1 to 5, wherein the electric charge is a light emitter.

Images