Storage battery monitoring system and control program

Abstract

In a storage battery monitoring system (10), a plurality of storage battery modules (30, 60) provided with storage batteries (31, 61) and conversion circuits (40, 70) are connected in parallel to a charging device (29) and a load (21). A parameter acquisition unit (16c) acquires a prescribed parameter before the start of energization and after energization of an estimation storage battery that estimates the full charge capacity. A control unit (16b) starts energization of at least one of non-estimation storage batteries that does not estimate the full charge capacity when an energization request for the storage battery is input, and controls the conversion circuit corresponding to the estimation storage battery and the non-estimation storage battery so that, after a prescribed time has elapsed from when the energization request is input, and after the prescribed parameter is acquired in the estimation storage battery, energization is started, and the energization time of the estimation storage battery is shorter than the energization time of the non-estimation storage battery.

Description

Battery monitoring system and control program CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Japanese Application No. 2023-116076 filed on July 14, 2023, the contents of which are incorporated herein by reference.

[0002] The present disclosure relates to a battery monitoring system.

[0003] For example, one system (see Patent Document 1) includes a system that disconnects a battery block (hereinafter referred to as an “estimation battery block”) from the parallel connection, where the battery block for which a full charge capacity is to be estimated is one that is connected in parallel to a load, until polarization is eliminated, and then discharges or charges the battery using the other battery blocks. The system then acquires the pre-charge voltage of the estimation battery block after polarization elimination, and acquires the post-charge voltage of the estimation battery block after a predetermined charge amount is charged to the estimation battery block (see Patent Document 1). The system described in Patent Document 1 calculates pre-charge and post-charge charge rates (predetermined parameters) from the acquired post-polarization voltages (predetermined parameters) of the estimation battery block before and after charging, and estimates the full charge capacity from these values ​​and the predetermined charge amount. The system described in Patent Document 1 is said to ensure time for polarization elimination of the estimation battery block without interfering with the use of battery blocks other than the estimation battery block, thereby enabling accurate estimation of the full charge capacity of the estimation battery block.

[0004] JP 2014-115127 A

[0005] However, in the system described in Patent Document 1, the timing for completing charging of the estimated battery block to a predetermined amount of charge is delayed by the time required to leave the battery to deflate (hereinafter referred to as "polarization deflation time") before charging (energizing) the estimated battery block. Therefore, when multiple battery blocks are used for discharging immediately after charging, it is difficult to ensure the polarization deflation time after charging the estimated battery block.

[0006] A similar problem can also occur when calculating the charge rates before and after discharge (energization) and estimating the full charge capacity from these values ​​and a predetermined discharge amount. That is, if a polarization elimination time is ensured before discharging the estimated battery block and multiple battery blocks are used for charging immediately after discharging the estimated battery block, it is difficult to ensure a polarization elimination time after discharging the estimated battery block.

[0007] The present disclosure has been made to solve the above-mentioned problems, and its main purpose is to accurately obtain, in a battery monitoring system, specified parameters used to estimate the full charge capacity of a battery, even when the interval between each current application to the battery is short.

[0008] A first means for solving the above problem is a battery monitoring system in which a plurality of battery modules, each having a battery and a conversion circuit that converts power input from the battery to a primary-side terminal pair and outputs the converted power from a secondary-side terminal pair, are connected in parallel to at least one of a charging device and a load, the system comprising: a parameter acquisition unit that acquires predetermined parameters used to estimate the full charge capacity of an estimated battery before and after energization of the estimated battery, which is the battery whose full charge capacity is to be estimated; and a control unit that controls the conversion circuits of the plurality of battery modules, respectively, to control the energization states of the batteries of the plurality of battery modules, respectively; When a request for power supply to the multiple storage batteries is input, the control unit starts power supply to at least one of the non-estimation storage batteries, which are storage batteries for which the full charge capacity is not estimated, and after a predetermined time has elapsed since the power supply request was input, starts power supply to the estimated storage battery after acquiring the predetermined parameters in the estimated storage battery using the parameter acquisition unit, and controls the conversion circuit corresponding to the estimated storage battery and the conversion circuit corresponding to the non-estimation storage battery so that the power supply time of the estimated storage battery in response to the power supply request is shorter than the power supply time of the non-estimation storage battery in response to the power supply request.

[0009] According to the above configuration, in the power supply system, a plurality of storage battery modules each including a storage battery and a conversion circuit that converts power input from the storage battery to a pair of primary terminals and outputs the converted power from a pair of secondary terminals are connected in parallel to at least one of a charging device and a load, so that the storage battery can be charged (energized) by the charging device and the storage battery can be discharged (energized) to the load.

[0010] The parameter acquisition unit acquires predetermined parameters used to estimate the full charge capacity of the estimated storage battery before the start of current application to the estimated storage battery and after the end of current application. In order to accurately acquire the predetermined parameters, it is necessary to ensure a depolarization time in the estimated storage battery before acquiring the predetermined parameters. Furthermore, the control unit can control the current application states of the storage batteries of the plurality of storage battery modules by respectively controlling the conversion circuits of the plurality of storage battery modules.

[0011] Here, when a request for energization for the plurality of storage batteries is input, the control unit starts energization of at least one of the non-estimated storage batteries. Therefore, the request for energization for the plurality of storage batteries can be fulfilled by at least one of the non-estimated storage batteries. Meanwhile, the control unit starts energization after a predetermined time has elapsed since the input of the energization request, and after the parameter acquisition unit acquires the predetermined parameters for the estimated storage battery. Therefore, even if the interval between the end of energization immediately before the input of the energization request and the input of the energization request is short, a predetermined time can be secured as a depolarization time for the estimated storage battery before acquiring the predetermined parameters. Then, energization of the estimated storage battery can be started after acquiring the predetermined parameters. However, the timing of starting energization for the estimated storage battery is later than the timing of starting energization for the non-estimated storage batteries.

[0012] In this regard, the control unit controls the conversion circuit corresponding to the estimated battery and the conversion circuit corresponding to the non-estimated battery so that the energization time of the estimated battery in response to the energization request is shorter than the energization time of the non-estimated battery in response to the energization request. Therefore, the timing of terminating energization of the estimated battery can be earlier than when the energization time of the estimated battery in response to the energization request is equal to or longer than the energization time of the non-estimated battery in response to the energization request. This makes it easier to ensure depolarization time for the estimated battery after energization of the estimated battery is terminated. Therefore, even if the interval between each energization of the battery is short, the predetermined parameters used to estimate the full charge capacity of the battery can be accurately acquired.

[0013] Specifically, as in the second aspect, the predetermined parameter may be an open circuit voltage of the estimated battery measured when the time during which it can be assumed that no current is flowing through the estimated battery is equal to or longer than the predetermined time, or a state of charge of the estimated battery calculated based on the open circuit voltage. This configuration allows the full charge capacity of the estimated battery to be calculated accurately based on the open circuit voltage of the estimated battery. For example, the full charge capacity can be calculated using the formula: full charge capacity = charge amount × 100 / (state of charge after charging - state of charge before charging).

[0014] In a third means, the multiple storage battery modules are connected in parallel to the charging device, and the request for power supply to the multiple storage batteries is a request for charging the multiple storage batteries, and the control unit controls the conversion circuit corresponding to the estimated storage battery and the conversion circuit corresponding to the non-estimated storage battery so that the charging time of the estimated storage battery in response to the charging request is shorter than the charging time of the non-estimated storage battery in response to the charging request, thereby making the average value of the current flowing to the estimated storage battery greater than the average value of the current flowing to the non-estimated storage battery from the start to the end of charging of the multiple storage batteries.

[0015] According to the above configuration, when the power supply request is a charging request, the average value of the current flowing to the estimated storage battery and the non-estimated storage battery can be controlled, thereby easily shortening the charging time of the estimated storage battery compared to the charging time of the non-estimated storage battery.

[0016] In a fourth aspect, the control unit controls the conversion circuit corresponding to the estimated battery and the conversion circuit corresponding to the non-estimated battery to make the charging end timing of the estimated battery earlier than the charging end timing of the non-estimated battery. With this configuration, even if the charging start timing of the estimated battery is later than the charging start timing of the non-estimated battery, the charging end timing of the estimated battery can be made earlier than the charging end timing of the non-estimated battery. Therefore, it is easier to ensure a depolarization time for the estimated battery after the charging of the estimated battery is completed.

[0017] In the fifth means, the positive and negative electrodes of the storage battery are connected to the primary terminal pair of the conversion circuit, and the storage battery is connected in series to the secondary terminal pair of the conversion circuit.

[0018] According to the above configuration, the output voltage Vm of the storage battery module is the sum of the output voltage Vb of the storage battery and the output voltage Vo of the conversion circuit. Therefore, compared to a storage battery module in which storage batteries are connected in parallel to the secondary terminal pairs of the conversion circuit, the output voltage Vo required of the conversion circuit when the output voltage Vm of the storage battery module is required can be reduced. Therefore, the rated voltage of the conversion circuit can be lowered, and the rated capacity of the conversion circuit can be reduced, thereby enabling the conversion circuit to be made more compact.

[0019] In a sixth aspect, the control unit controls the conversion circuit corresponding to the estimated storage battery so that, from the start of charging of at least one of the non-estimated storage batteries until the start of charging of the estimated storage battery, the current flowing to the estimated storage battery approaches 0. With this configuration, even if the storage battery module corresponding to the estimated storage battery is not disconnected from the charging device by a relay or the like, the current flowing to the estimated storage battery can be made to approach 0, and polarization of the estimated storage battery can be suppressed.

[0020] In a seventh aspect, the control unit controls the conversion circuit corresponding to the estimated battery and the conversion circuit corresponding to the non-estimated battery so that, from the start to the end of charging of the estimated battery, the voltage applied to the estimated battery from the conversion circuit corresponding to the estimated battery is higher than the voltage applied to the non-estimated battery from the conversion circuit corresponding to the non-estimated battery. With this configuration, by controlling the voltage applied to the estimated battery and the non-estimated battery, it is possible to easily control the current flowing to the estimated battery and the non-estimated battery.

[0021] If the voltage difference between the output voltage of the non-estimated storage battery and the output voltage of the estimated storage battery becomes too large, it becomes difficult to adjust the output voltage of the storage battery module corresponding to the non-estimated storage battery to match the output voltage of the storage battery module corresponding to the estimated storage battery using a conversion circuit.

[0022] In this regard, in an eighth aspect, when a voltage difference between the output voltage of the non-estimated battery and the output voltage of the estimated battery is greater than a predetermined voltage difference from the start to the end of charging of the plurality of batteries, the control unit controls the conversion circuit corresponding to the estimated battery and the conversion circuit corresponding to the non-estimated battery to increase the current amount of power or current input to at least one battery included in the non-estimated battery or the estimated battery with the lower output voltage, or to decrease the current amount of power or current input to at least one battery included in the non-estimated battery or the estimated battery with the higher output voltage. This configuration can prevent the voltage difference between the output voltage of the non-estimated battery and the estimated battery from becoming too large. Therefore, a state in which the conversion circuit can adjust the output voltage of the battery module corresponding to the non-estimated battery to match the output voltage of the battery module corresponding to the estimated battery can be maintained.

[0023] In a ninth aspect, the control unit selects, as the estimation battery, at least one of the storage batteries that is predicted to be most deteriorated and the storage battery that has not had its full charge capacity calculated for the longest period of time among the storage batteries. This configuration makes it possible to estimate the full charge capacity of a storage battery that is predicted to have a low full charge capacity or a storage battery that is predicted to have a large error in its known full charge capacity. Therefore, when controlling the power supply to the multiple storage batteries using the full charge capacities of the multiple storage batteries, the effectiveness of the control can be improved.

[0024] When energizing the non-estimation batteries, if the total power of the energized non-estimation batteries is significantly smaller than the power that can be supplied to the battery monitoring system, the energization efficiency of the battery monitoring system may decrease.

[0025] In this regard, in a tenth aspect, the control unit determines the number of batteries to be selected as the estimated batteries when energization of the non-estimation batteries begins, based on the available power of each battery and the available power of the battery monitoring system. With this configuration, the number of batteries to be selected as the estimated batteries when energization of the non-estimation batteries begins, and ultimately the number of non-estimation batteries to be energized, can be determined taking into account the available power of each battery and the available power of the battery monitoring system. Therefore, a decrease in the energization efficiency of the battery monitoring system can be suppressed.

[0026] In an eleventh aspect, if the available power of the battery monitoring system is greater than the total available power of all the non-estimation batteries between the start of energization of all the non-estimation batteries and the start of energization of the estimation battery, the control unit changes at least one of the batteries selected as the estimation battery at the start of energization of the non-estimation batteries to the non-estimation battery and starts energizing the non-estimation batteries. With this configuration, if the available power of the battery monitoring system is not reached even when all the non-estimation batteries are energized, at least one of the batteries selected as the estimation battery at the start of energization of the non-estimation batteries can be changed to the non-estimation battery to increase the total available power of the non-estimation batteries. Therefore, even if too many batteries are selected as the estimation battery at the start of energization of the non-estimation batteries, a decrease in the energization efficiency of the battery monitoring system can be suppressed.

[0027] If a next current supply request for multiple storage batteries is input between the start and end of current supply to the estimated storage battery, and current supply to the estimated storage battery is started immediately, it is not possible to ensure time for the estimated storage battery to depolarize and obtain the specified parameters before current supply to the estimated storage battery begins in response to the next current supply request.

[0028] In this regard, in a twelfth aspect, the control unit terminates energization of the estimated storage battery when a next energization request for the plurality of storage batteries is input between the start and end of energization of the estimated storage battery, and starts energization after the predetermined time has elapsed since the end of energization of the estimated storage battery and the parameter acquisition unit has acquired the predetermined parameter for the estimated storage battery. With this configuration, even if a next energization request for the plurality of storage batteries is input between the start and end of energization of the estimated storage battery, it is possible to ensure a predetermined time as a polarization elimination time for the estimated storage battery and acquire the predetermined parameter.

[0029] The thirteenth means is a control program applied to a storage battery monitoring system in which a plurality of storage battery modules, each including a storage battery and a conversion circuit that converts power input from the storage battery to a primary-side terminal pair and outputs the converted power from a secondary-side terminal pair, are connected in parallel to at least one of a charging device and a load, the control program including: a process of acquiring predetermined parameters used to estimate the full charge capacity of an estimated storage battery before and after energization of the estimated storage battery, which is the storage battery whose full charge capacity is to be estimated; and a process of controlling the energization states of the storage batteries of the plurality of storage battery modules by controlling the conversion circuits of the plurality of storage battery modules, respectively. When a request for energization is input for the plurality of storage batteries, energization is started for at least one of the non-estimation storage batteries, which are storage batteries for which full charge capacity is not estimated, and after a predetermined time has elapsed since the input of the energization request, energization is started for the estimation storage battery after the predetermined parameters have been acquired, and the computer is caused to execute a process of controlling the conversion circuit corresponding to the estimation storage battery and the conversion circuit corresponding to the non-estimation storage battery so that the energization time of the estimation storage battery in response to the energization request is shorter than the energization time of the non-estimation storage battery in response to the energization request.

[0030] According to the above configuration, by causing a computer to execute a control program applied to the storage battery monitoring system, it is possible to achieve the same effects as those of the first means.

[0031] The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which Fig. 1 is a circuit diagram of a power supply system according to a first embodiment, Fig. 2 is a circuit diagram showing an example of a conversion circuit, Fig. 3 is a time chart showing how full charge capacity is calculated in an ideal use case, Fig. 4 is a graph showing the relationship between OCV and SOC and how SOC is acquired, Fig. 5 is a schematic diagram showing the relationship between use cases and whether or not SOH can be calculated, Fig. 6 is a schematic diagram showing an overview of full charge capacity calculation according to the first embodiment, Fig. 7 is a flowchart showing the procedure for calculating full charge capacity according to the first embodiment, Fig. 8 is a time chart showing how full charge capacity calculation according to the first embodiment is performed, and Fig. 9 is a schematic diagram showing an overview of a modified example of full charge capacity calculation. 10 is a circuit diagram of a modified example of the power supply system, FIG. 11 is a circuit diagram of a power supply system of the second embodiment, FIG. 12 is a flowchart showing the procedure for calculating the full charge capacity of the second embodiment, FIG. 13 is a schematic diagram showing the relationship between the number of non-estimated storage batteries and estimated storage batteries and the chargeable current of the system, FIG. 14 is a circuit diagram of another modified example of the power supply system, FIG. 15 is a circuit diagram of a modified example of the conversion circuit, FIG. 16 is a circuit diagram of another modified example of the conversion circuit, FIG. 17 is a circuit diagram of a modified example of the storage battery module, FIG. 18 is a circuit diagram of another modified example of the storage battery module, and FIG. 19 is a schematic diagram showing an outline of another modified example of the full charge capacity calculation.

[0032] First Embodiment A first embodiment of a power supply system mounted on a vehicle to supply power to a load will be described below with reference to the drawings. The vehicle may be, for example, a hybrid vehicle or an electric vehicle, and is equipped with an activation switch (e.g., an IG switch or a start switch) for activating the vehicle. The vehicle is placed in an operating state (in operation) by turning on the activation switch (not shown), and placed in a stopped state (stopped) by turning off the activation switch.

[0033] 1 , the power supply system 10 includes buses 11 and 12 (power supply buses), a first storage battery module 30, a second storage battery module 60, a voltage sensor 13, a current sensor 19, an ECU (Electronic Control Unit) 16, etc. The positive side of the buses is referred to as bus 11, and the negative side of the buses is referred to as bus 12. The bus 12 is grounded.

[0034] A first storage battery module 30 (storage battery module), a second storage battery module 60 (storage battery module), a load 21, an external charger 29, and a voltage sensor 13 are connected in parallel to the buses 11 and 12. The storage battery modules 30 and 60 input and output power to and from the buses 11 and 12. The load 21 inputs power from the buses 11 and 12, or inputs and outputs power to and from the buses 11 and 12. The external charger 29 charges the storage batteries 31 and 61 by inputting power to the buses 11 and 12. The voltage sensor 13 detects a bus voltage Vbus, which is the voltage between the buses 11 and 12. The current sensor 19 detects a current flowing through the bus 12 (the load 21 or the external charger 29).

[0035] The load 21 is, for example, a combination of an inverter and a motor generator (MG) (a motor unit with an inverter), an electric heater, a DC-DC converter, or the like. The MG (motor generator) drives, for example, an electric vehicle using power supplied from the inverter, or generates electricity regeneratively using rotational force imparted by the electric vehicle. The inverter converts power between the buses 11 and 12 and the MG. The electric heater generates heat using voltage supplied from the buses 11 and 12, for example, to warm the interior of the vehicle or the battery. The DC-DC converter converts DC power supplied from the buses 11 and 12, for example, to supply DC power, or converts DC power supplied from a solar panel or the like to supply DC power to the buses 11 and 12. The load 21 may be singular or plural.

[0036] The external charger 29 (charging device) is a well-known DC charger installed outside the vehicle. The rated charging power (chargeable power) of the external charger 29 is predetermined based on the specifications of the external charger 29. For example, the external charger 29 has a rated voltage of 400 V and a rated power of 150 kW. The external charger 29 is connected to the buses 11 and 12 (vehicle) via charging cables 29 a and 29 b and outputs charging power to the buses 11 and 12. The external charger 29 can communicate with the ECU 16. The external charger 29 transmits information about charging, such as its own rated charging power, to the ECU 16. When the charging cables 29 a and 29 b are connected to the buses 11 and 12, the external charger 29 transmits a signal indicating the connection to the ECU 16.

[0037] The first storage battery module 30 includes a first storage battery 31, a first current sensor 33, a first drive circuit 35, a first conversion circuit 40, and relays 40a and 40b. The first storage battery 31 (storage battery) is a high-voltage secondary battery, such as a lithium-ion battery or a nickel-metal hydride battery, and may be of any type. The first current sensor 33 (current sensor) detects the current flowing through the first storage battery 31. The value detected by the first current sensor 33 is input to the ECU 16 and used, for example, to calculate the state of charge (SOC) [%] of the first storage battery 31. The first drive circuit 35 (drive circuit) drives a switching element (described below) included in the first conversion circuit 40 to turn on and off. The first drive circuit 35 is controlled by the ECU 16. The relays 40a and 40b connect and disconnect the storage battery module 30 to and from the buses 11 and 12, respectively. The first storage battery 31 (storage battery) may be a secondary battery that is not a high voltage battery.

[0038] The first conversion circuit 40 (conversion circuit) includes a primary-side terminal pair, that is, a primary-side positive terminal 41 and a negative terminal 42, and a secondary-side terminal pair, that is, a secondary-side positive terminal 47 and a negative terminal 48. The negative terminal of the first storage battery 31 is connected to the bus 12. The primary-side positive terminal 41 is connected to the positive terminal of the first storage battery 31, and the primary-side negative terminal 42 is connected to the negative terminal of the first storage battery 31. The secondary-side negative terminal 48 is also connected to the positive terminal of the first storage battery 31. The secondary-side positive terminal 47 is connected to the bus 11. That is, the positive and negative terminals of the first storage battery 31 are connected to the primary-side terminal pair 41, 42 of the first conversion circuit 40, respectively, and the first storage battery 31 is connected in series to the secondary-side terminal pair 47, 48 of the first conversion circuit 40. The first conversion circuit 40 converts the power input from the first storage battery 31 to the pair of primary side terminals 41 and 42 and outputs it from the pair of secondary side terminals 47 and 48. The first conversion circuit 40 is a bidirectional conversion circuit that can also convert the power input to the pair of secondary side terminals 47 and 48 and output it from the pair of primary side terminals 41 and 42.

[0039] The second storage battery module 60 has a configuration similar to that of the first storage battery module 30 and includes a second storage battery 61 (storage battery), a second current sensor 63 (current sensor), a second drive circuit 65 (drive circuit), a second conversion circuit 70, relays 70a and 70b, etc. The second conversion circuit 70 (conversion circuit) has a configuration similar to that of the first conversion circuit 40 and includes a primary-side terminal pair consisting of a primary-side positive terminal 71 and a negative terminal 72, and a secondary-side terminal pair consisting of a secondary-side positive terminal 77 and a negative terminal 78. The connection configuration of these components is also similar to that of the first storage battery module 30, and therefore the above description of the first storage battery module 30 is incorporated herein. Note that although the first storage battery module 30 and the second storage battery module 60 have components with similar functions, the ratings and withstand voltages of the respective components may differ from each other.

[0040] FIG. 2 shows an example of a first conversion circuit 40. The first conversion circuit 40 is a well-known center-tap isolated DC-DC converter. The first conversion circuit 40 includes switching elements 43 to 46, 54, and 55, smoothing capacitors 50 and 57, a transformer 53, a reactor 56, voltage sensors 51 and 59, and current sensors 52 and 58. The switching elements 43 to 46, 54, and 55 are, for example, MOSFETs or IGBTs (insulated gate bipolar transistors). The switching elements 43 to 46 form a full-bridge circuit. The connection point between the switching element 43 and the switching element 44 and the connection point between the switching element 45 and the switching element 46 are connected to both ends of the primary coil of the transformer 53, respectively. The switching elements 54 and 55 are connected between both ends of the secondary coil of the transformer 53 and the reactor 56, respectively. The voltage sensor 51 detects the voltage between the negative terminal 42 and the positive terminal 41 on the primary side, i.e., the output voltage Vb (primary voltage) of the first storage battery 31. The current sensor 52 detects the input current Ii (primary current) that is the current input to the primary circuit. The voltage sensor 59 detects the voltage between the negative terminal 48 and the positive terminal 47 on the secondary side, i.e., the output voltage Vo (secondary voltage) of the first conversion circuit 40. The current sensor 58 detects the current flowing through the reactor 56, i.e., the output current Io (secondary current) of the first conversion circuit 40. The detected values ​​of the voltage sensors 51, 59 and the current sensors 52, 58 are input to the ECU 16.

[0041] The ECU 16 (control device) is configured as a microcomputer (computer) including, for example, a CPU, ROM, RAM, an input / output interface, etc. The ECU 16 controls the states of the relays 40a, 40b, 70a, 70b and the state of the load 21. Furthermore, the ECU 16 executes a control program applied to the power supply system 10 to realize functions of a bus voltage setting unit 16a, a control unit 16b, a parameter acquisition unit 16c, etc. The storage battery modules 30, 60, the control unit 16b, and the parameter acquisition unit 16c constitute a storage battery monitoring system.

[0042] The bus voltage setting unit 16a sets a bus voltage request value Vbus*, which is a voltage that is requested to be supplied from the buses 11 and 12 to the load 21. The bus voltage setting unit 16a sets the bus voltage request value Vbus* based on the state of the load 21.

[0043] The control unit 16b controls the output voltages Vo1 and Vo2 of the conversion circuits 40 and 70, respectively, so that the output voltages Vm1 and Vm2 of the storage battery modules 30 and 60 become the requested bus voltage value Vbus* (approach the requested bus voltage value Vbus*). For example, the control unit 16b controls the switching elements 43-46, 54, and 55 based on the detected values ​​of the voltage sensors 51 and 59 and the current sensors 52 and 58, thereby controlling the first output voltage Vo1 of the first conversion circuit 40 to become the requested first output voltage value Vo1* (approach the requested first output voltage value Vo1*). More specifically, the control unit 16b sets the requested first output voltage value Vo1* to a voltage obtained by subtracting the first output voltage Vb1 of the first storage battery 31 from the requested bus voltage value Vbus* (Vo1*=Vbus*−Vb1). Similarly, the control unit 16b controls the second output voltage Vo2 of the second conversion circuit 70 to become equal to (approach) the second output voltage request value Vo2*. Specifically, the second output voltage request value Vo2* is set to a voltage obtained by subtracting the second output voltage Vb2 of the second storage battery 61 from the bus voltage request value Vbus* (Vo2*=Vbus*−Vb2).

[0044] Furthermore, if the voltage difference between the first output voltage Vb1 of the first storage battery 31 and the second output voltage Vb2 of the second storage battery 61 becomes too large, it becomes difficult to adjust the output voltage Vm1 of the first storage battery module 30 and the second output voltage Vm2 of the second storage battery module 60 so that they match using the conversion circuits 40, 70.

[0045] FIG. 3 is a time chart showing how the full charge capacity is calculated in an ideal use case. When vehicle travel ends at timing t11, the polarization of the storage batteries 31, 61 gradually disappears. When the voltages of the storage batteries 31, 61 stabilize at timing t12, the parameter acquisition unit 16c causes the voltage sensor 51 to detect the pre-charge OCV (Open Circuit Voltage) of the storage batteries 31, 61 with the circuits of the storage batteries 31, 61 open. Thereafter, the control unit 16b controls the conversion circuits 40, 70 to charge the storage batteries 31, 61 with charging power from the external charger 29. When charging of the storage batteries 31, 61 ends at timing t13, the polarization of the storage batteries 31, 61 gradually disappears. When the voltages of the storage batteries 31, 61 stabilize at timing t14, the parameter acquisition unit 16c causes the voltage sensor 51 to detect the post-charge OCV of the storage batteries 31, 61. The pre-charge OCV and the post-charge OCV correspond to predetermined parameters used to estimate the full charge capacity of the storage batteries 31 and 61 .

[0046] FIG. 4 is a graph showing the relationship between OCV and SOC and how the SOC is acquired. The parameter acquisition unit 16c stores the graph of FIG. 4, which defines the relationship between OCV and SOC in a stable state. The relationship between OCV and SOC in a stable state can be acquired in advance based on tests or the like. The parameter acquisition unit 16c calculates the pre-charge SOC (predetermined parameter) by applying the pre-charge OCV detected at timing t12 in FIG. 3 to the graph of FIG. 4. The parameter acquisition unit 16c calculates the post-charge SOC (predetermined parameter) by applying the post-charge OCV detected at timing t14 in FIG. 3 to the graph of FIG. 4. The parameter acquisition unit 16c (ECU 16) then calculates the full charge capacity using the formula: full charge capacity [Ah] = charge amount × 100 / (post-charge SOC - pre-charge SOC). The charge amount is the integrated value of the current from the start to the end of charging, and can be calculated, for example, by integrating the currents detected by the current sensors 33, 63. The parameter acquisition unit 16c (ECU 16) calculates the SOH of the storage batteries 31, 61 using the formula: SOH [%] = current full charge capacity × 100 / full charge capacity at the time of manufacture. Note that if the pre-charge OCV (post-charge OCV) is detected when the voltage of the storage batteries 31, 61 is not stable, the pre-charge OCV (post-charge OCV) to be applied to the graph in FIG. 4 cannot be accurately detected. In this case, the full charge capacity of the storage batteries 31, 61 cannot be accurately estimated, and therefore the SOH of the storage batteries 31, 61 cannot be accurately estimated.

[0047] 5 is a schematic diagram showing the relationship between use cases and whether or not the SOH can be calculated. Note that the star marks indicate the timing at which the OCV after stabilization can be detected.

[0048] In an ideal use case, after the vehicle has finished traveling, a time period during which the storage batteries 31, 61 are left to deflate (polarization deflation time) can be secured, and the stabilized pre-charge OCV can be detected at timing t21. Even after the charging of the storage batteries 31, 61 has finished, a time period during which the storage batteries 31, 61 are allowed to deflate their polarization can be secured, and the stabilized post-charge OCV can be detected at timing t25. Therefore, the SOH can be accurately estimated.

[0049] In the problematic use case, the user charges the storage battery 31, 61 immediately after the vehicle has finished traveling. Therefore, it is not possible to ensure time for the storage battery 31, 61 to deflate, and it is not possible to detect the pre-charge OCV after the storage battery 31, 61 has stabilized. Therefore, it is not possible to accurately estimate the SOH.

[0050] In the comparative example, when the user charges the storage batteries 31, 61 at timing t21 immediately after the vehicle has stopped traveling, charging of the first storage battery 31, for example, for estimating the full charge capacity, is prohibited from timing t21 to timing t22. Therefore, the stabilized pre-charge OCV can be detected at timing t22. However, the charging end timing t24 of the first storage battery 31 is later than the charging end timing t23 of, for example, the second storage battery 61, which starts charging immediately after the charging operation. Therefore, when the user requests traveling at timing t25, the first storage battery 31 cannot have enough time to depolarize, and the stabilized post-charge OCV of the first storage battery 31 cannot be detected. Therefore, the SOH cannot be accurately estimated.

[0051] FIG. 6 is a schematic diagram illustrating an overview of full charge capacity calculation in this embodiment. In this embodiment, when the user performs a charging operation on the storage batteries 31, 61 at timing t31 immediately after the vehicle has finished traveling, charging of the non-estimation storage battery, which is a storage battery whose full charge capacity is not estimated, begins. At this time, charging is performed, for example, using the rated charging power of the external charger 29. Meanwhile, the estimation storage battery, which is a storage battery whose full charge capacity is estimated, is left to eliminate polarization from timing t31 to timing t32. Therefore, at timing t32, the stabilized pre-charge OCV can be detected. After detecting the pre-charge OCV, charging of the estimation storage battery begins, and the charging power of the non-estimation storage battery and the estimation storage battery is controlled. At this time, the charging power of the estimation storage battery is set to be greater than the charging power of each non-estimation storage battery. This allows the charging time Te2 of the estimation storage battery to be shorter than the charging time Te1 of the non-estimation storage battery. As a result, the estimation storage battery is fully charged, for example, at timing t33. Thereafter, the estimation storage battery is left to eliminate polarization. When the user requests driving at timing t34, the estimated battery has had enough time to deflate polarization, and the post-charge OCV after stabilization of the estimated battery can be detected. Therefore, the SOH can be accurately estimated.

[0052] 7 is a flowchart showing the procedure for calculating the full charge capacity according to this embodiment. This series of processes is repeatedly executed at a predetermined interval by the ECU 16. Here, an example will be described in which the first storage battery 31 is determined to be the estimated storage battery and the second storage battery 61 is determined to be the non-estimated storage battery.

[0053] First, it is determined whether it is time to start charging (S10). For example, when the charging cables 29a, 29b are connected to the buses 11, 12, and a signal indicating this connection is received from the external charger 29, it is determined that it is time to start charging (a charging request has been made, a power supply request has been made). If it is determined that it is time to start charging (YES in S10), a non-estimated battery and an estimated battery are determined (S11). Specifically, at least one of the battery predicted to be most degraded among the multiple batteries 31, 61 and the battery for which the full charge capacity has not been calculated for the longest period among the multiple batteries 31, 61 is selected as the estimated battery. For example, the battery with the smallest most recently estimated full charge capacity is selected as the battery predicted to be most degraded. For example, the battery for which the longest time has elapsed since the most recently calculated full charge capacity is selected as the battery for which the full charge capacity has not been calculated for the longest period. Then, of the multiple storage batteries 31, 61, for example, the first storage battery 31 selected as the estimated storage battery is determined to be the estimated storage battery, and the remaining second storage battery 61 not selected as the estimated storage battery is determined to be the non-estimated storage battery. Note that if the storage battery predicted to be most degraded and the storage battery for which the full charge capacity has not been calculated for the longest period are selected and are different, either one may be determined to be the estimated storage battery. Furthermore, the storage battery with the highest SOC among the multiple storage batteries 31, 61 may be selected as the estimated storage battery, or the estimated storage battery may be selected randomly. Next, charging of the non-estimated storage battery is started (S12).

[0054] On the other hand, if it is determined in S10 that it is not the timing to start charging (S10: NO), it is determined whether the elapsed time since the start of charging is equal to a predetermined time (S13). Specifically, it is determined whether the elapsed time since the start of charging is equal to a time threshold set, for example, longer than the standby time required for the first storage battery 31 (storage battery) to dissipate polarization and stabilize its OCV. The time threshold may be a variable value so that it is set longer as the temperature of the estimated storage battery decreases. Furthermore, if the estimated storage battery has already been left for a time Te3 before the timing to start charging, the time obtained by subtracting the time Te3 from the time threshold may be set as a new time threshold. The elapsed time since the start of charging may be, for example, the time elapsed since it was determined in S13 that it is the timing to start charging, or the time elapsed since charging of the non-estimated storage battery was started in S12. If it is determined that the elapsed time since the start of charging is equal to the predetermined time (S13: YES), the pre-charge OCV (predetermined parameter) of the estimated storage battery is acquired (S14). Specifically, in a state where the circuit of the estimated battery is open (a state where it can be assumed that no current is flowing through the estimated battery), the voltage sensor 51 detects the output voltage Vb of the estimated battery. Then, charging of the estimated battery is started (S15).

[0055] Furthermore, if it is determined in S13 that the elapsed time since the start of charging is not equal to the predetermined time (S13: NO), it is determined whether any storage battery satisfies the charging termination condition (S16). Specifically, among the non-estimated storage battery and the estimated storage battery, a storage battery whose output voltage Vb has reached the full charge voltage threshold is determined to be a storage battery that satisfies the charging termination condition. The full charge voltage threshold is set to a value that allows determination that the storage battery 31, 61 is fully charged. If it is determined in this determination that any storage battery satisfies the charging termination condition (S16: YES), charging of the storage battery that satisfies the charging termination condition is terminated (S17). To terminate charging of the storage battery, for example, the conversion circuits 40, 70 may be controlled so that no current flows through the storage batteries 31, 61, or the storage batteries 31, 61 may be disconnected from the buses 11, 12 by the relays 40a, 40b, 70a, 70b, respectively. On the other hand, if it is determined that no storage battery satisfies the charging termination condition (S16: NO), the process proceeds to S18.

[0056] Next, the charging power of each storage battery 31, 61 is controlled according to the state of the storage battery that has started or finished charging (S18). Here, for example, when charging of the non-estimated storage battery 61 has started and the estimated storage battery 31 is left alone to eliminate polarization, the conversion circuit 70 corresponding to the non-estimated storage battery 61 is controlled to charge the non-estimated storage battery 61 with the rated charging power of the external charger 29. At this time, for example, the conversion circuit 40 corresponding to the estimated storage battery 31 is controlled so that it can be considered that no current is flowing to the estimated storage battery 31 (the current flowing to the estimated storage battery approaches zero), or the estimated storage battery 31 is disconnected from the buses 11, 12 by the relays 40a, 40b, respectively. The ECU 16 can obtain the rated charging power of the external charger 29 through communication with the external charger 29. Furthermore, when charging of the estimated battery 31 has also started and the non-estimated battery 61 and the estimated battery 31 are being charged, the conversion circuit 40 corresponding to the estimated battery 31 and the conversion circuit 70 corresponding to the non-estimated battery 61 are controlled so that the charging time of the estimated battery 31 in response to the connection of the charging cables 29 a, 29 b (charging request) is shorter than the charging time of the non-estimated battery 61 in response to the charging request. Specifically, by controlling the conversion circuit 40 corresponding to the estimated battery 31 and the conversion circuit 70 corresponding to the non-estimated battery 61, the average value of the current flowing through the estimated battery 31 is made larger than the average value of the current flowing through the non-estimated battery 61 from the start to the end of charging of the multiple batteries 31, 61. More specifically, the conversion circuit 40 corresponding to the estimated battery 31 and the conversion circuit 70 corresponding to the non-estimated battery 61 are controlled so that the output voltage Vo applied from the conversion circuit 40 corresponding to the estimated battery 31 to the estimated battery 31 is higher than the output voltage Vo applied from the conversion circuit 70 corresponding to the non-estimated battery 61 to the non-estimated battery 61. When the charging termination condition for the non-estimated storage battery 61 or the estimated storage battery 31 is met and only one of the non-estimated storage battery 61 and the estimated storage battery 31 is being charged, the one of the batteries being charged is charged using the rated charging power of the external charger 29.

[0057] Next, it is determined whether charging of the estimated battery has ended and whether the predetermined time or more has elapsed since the end of charging of the estimated battery (S19). If this determination is negative (S19: NO), this series of processes is temporarily terminated (END). On the other hand, if this determination is positive (S19: YES), the post-charge OCV (predetermined parameter) of the estimated battery is acquired (S20). Based on the acquired pre-charge OCV and post-charge OCV and the charge amount from the start to the end of charging of the estimated battery, the pre-charge SOC and post-charge SOC, and full charge capacity are calculated (S21). Specifically, the pre-charge SOC (predetermined parameter) and post-charge SOC (predetermined parameter) are calculated by applying the acquired pre-charge OCV and post-charge OCV to the graph of FIG. 4. Then, the full charge capacity is calculated using the formula: full charge capacity [Ah] = charge amount × 100 / (post-charge SOC - pre-charge SOC). Then, this series of processes is terminated.

[0058] The processes of S14, S20, and S21 correspond to the processes performed by the parameter acquisition unit 16c, and the processes of S12, S15, and S18 correspond to the processes performed by the control unit 16b.

[0059] FIG. 8 is a time chart showing the manner in which full charge capacity is calculated in this embodiment. When a charging request is input at timing t41, charging of the non-estimated battery is initiated, and the estimated battery is left uncharged. When the elapsed time from the start of charging reaches a time threshold at timing t42, the OCV of the estimated battery is acquired. Then, charging of the estimated battery is initiated, and the charging current of the estimated battery is controlled to be greater than the charging current of the non-estimated battery. At timing t43, the output voltage Vb of the estimated battery reaches the full power receiving voltage threshold, and charging of the estimated battery is terminated. At timing t44, the output voltage Vb of the non-estimated battery reaches the full power receiving voltage threshold, and charging of the non-estimated battery is terminated. That is, the control unit 16b controls the conversion circuit corresponding to the estimated battery and the conversion circuit corresponding to the non-estimated battery to make the charging end timing t43 of the estimated battery earlier than the charging end timing t44 of the non-estimated battery. When the vehicle is started for traveling at timing t45, the time threshold value corresponding to the predetermined time has elapsed since the charging end timing t43 of the estimated battery, and the OCV of the estimated battery is acquired.

[0060] The present embodiment described above in detail has the following advantages.

[0061] When a charge request for the multiple storage batteries 31, 61 is input, the control unit 16b starts charging, for example, the non-estimated storage battery 61. Therefore, the charge request for the multiple storage batteries 31, 61 can be satisfied by the non-estimated storage battery 61. On the other hand, the control unit 16b starts charging after a predetermined time has elapsed since the input of the charge request, for example, after the parameter acquisition unit 16c acquires predetermined parameters for the estimated storage battery 31. Therefore, even if the interval between the end of charging immediately before the input of the charge request and the input of the charge request is short, a predetermined time can be secured as a polarization elimination time for the estimated storage battery 31 before acquiring the predetermined parameters. Then, charging of the estimated storage battery 31 can be started after acquiring the predetermined parameters.

[0062] The control unit 16b controls the conversion circuit 40 corresponding to the estimated battery 31 and the conversion circuit 70 corresponding to the non-estimated battery 61 so that the charging time of the estimated battery 31 in response to the charging request is shorter than the charging time of the non-estimated battery 61 in response to the charging request. Therefore, the charging end timing t43 of the estimated battery 31 can be made earlier than when the charging time of the estimated battery 31 in response to the charging request is equal to or longer than the charging time of the non-estimated battery 61 in response to the charging request. This makes it easier to ensure a depolarization time for the estimated battery 31 after charging of the estimated battery 31 is completed. Therefore, even when the interval between discharges before and after charging the batteries 31, 61 is short, the predetermined parameters used to estimate the full charge capacities of the batteries 31, 61 can be accurately acquired.

[0063] The predetermined parameters are the OCV of the estimated battery 31, which is measured when the time during which it can be assumed that no current is flowing through the estimated battery 31 is equal to or longer than a predetermined time, and the SOC of the estimated battery 31, which is calculated based on the OCV. With this configuration, the full charge capacity of the estimated battery 31 can be calculated with high accuracy based on the OCV of the estimated battery 31.

[0064] By controlling the average values ​​of the currents flowing through the estimated battery 31 and the non-estimated battery 61, the charging time of the estimated battery 31 can be easily made shorter than the charging time of the non-estimated battery 61.

[0065] The control unit 16b controls, for example, the conversion circuit 40 corresponding to the estimated battery 31 and the conversion circuit 70 corresponding to the non-estimated battery 61 to make the charging end timing t43 of the estimated battery 31 earlier than the charging end timing t44 of the non-estimated battery 61. With this configuration, even if the charging start timing t42 of the estimated battery 31 is later than the charging start timing t41 of the non-estimated battery 61, the charging end timing t43 of the estimated battery 31 can be made earlier than the charging end timing t44 of the non-estimated battery 61. Therefore, it becomes easier to ensure a depolarization time for the estimated battery 31 after the charging of the estimated battery 31 is completed.

[0066] The output voltage Vm of the storage battery modules 30, 60 is the sum of the output voltage Vb of the storage batteries 31, 61 and the output voltage Vo of the conversion circuits 40, 70. Therefore, compared to a storage battery module in which the storage batteries 31, 61 are connected in parallel to the secondary-side terminal pairs 47, 48, 77, 78 of the conversion circuits 40, 70, when the output voltage Vm is required of the storage battery modules 30, 60, the output voltage Vo required of the conversion circuits 40, 70 can be reduced. Therefore, the rated voltage of the conversion circuits 40, 70 can be lowered, and the rated capacity of the conversion circuits 40, 70 can be reduced, thereby enabling the conversion circuits 40, 70 to be made smaller.

[0067] The control unit 16b controls the conversion circuit 40 corresponding to the estimated storage battery 31 so as to bring the current flowing through the estimated storage battery 31 close to zero, for example, from the time when charging of the non-estimated storage battery 61 starts until charging of the estimated storage battery 31 starts. With this configuration, even if the storage battery module 30 corresponding to the estimated storage battery 31 is not disconnected from the external charger 29 by the relays 40a, 40b, the current flowing through the estimated storage battery 31 can be brought close to zero, and polarization of the estimated storage battery 31 can be suppressed.

[0068] The control unit 16b controls the conversion circuit 40 corresponding to the estimated battery 31 and the conversion circuit 70 corresponding to the non-estimated battery 61 so that the voltage applied to the estimated battery 31 from the conversion circuit 40 corresponding to the estimated battery 31 is higher than the voltage applied to the non-estimated battery 61 from the conversion circuit 70 corresponding to the non-estimated battery 61, for example, from the start to the end of charging of the estimated battery 31. With this configuration, by controlling the voltages applied to the estimated battery 31 and the non-estimated battery 61, the current flowing through the estimated battery 31 and the non-estimated battery 61 can be easily controlled.

[0069] The control unit 16b selects, as the estimated battery, at least one of the storage batteries 31, 61 that is predicted to be the most deteriorated and the storage battery 31, 61 that has not had its full charge capacity calculated for the longest period of time. This configuration makes it possible to estimate the full charge capacity of a storage battery that is predicted to have a low full charge capacity or a storage battery that is predicted to have a large error in its known full charge capacity. Therefore, when controlling the power supply to the storage batteries 31, 61 using the full charge capacities of the storage batteries 31, 61, the effectiveness of the control can be improved.

[0070] The above-described advantageous effects can be achieved by causing the ECU 16 (computer) to execute a control program applied to the storage battery monitoring system (power supply system 10).

[0071] The first embodiment can be modified as follows: The same parts as those in the first embodiment are denoted by the same reference numerals and the description thereof will be incorporated herein.

[0072] The charging end timing t44 of the non-estimated storage battery 61 may be earlier than the charging end timing t43 of the estimated storage battery 31. Even in this case, if the charging time of the estimated storage battery 31 in response to the charging request is shorter than the charging time of the non-estimated storage battery 61 in response to the charging request, it becomes easier to ensure a depolarization time for the estimated storage battery 31 after charging of the estimated storage battery 31 is completed.

[0073] Whether the non-estimation battery 61 is charged by the external charger 29 can be switched by opening and closing the relays 70a and 70b.

[0074] 9 , the parameter acquisition unit 16c acquires the OCV at timing t52, a predetermined time after the input of a charge request at timing t51. It is assumed that a driving request (a discharge request for the multiple storage batteries 31, 61, a next current request) is input between the start and end of current supply to the estimated storage battery. In this case, if discharge of the estimated storage battery is started immediately, it is not possible to ensure time for depolarization of the estimated storage battery and acquire the OCV (predetermined parameter) before the start of discharge of the estimated storage battery in response to the driving request.

[0075] Therefore, the control unit 16b may perform the following control when a travel request is input between the start and end of charging (energization) of the estimated battery. That is, the control unit 16b may end charging of the estimated battery when the travel request is input at timing t53, and may start discharging (energization) of the estimated battery after a predetermined time has elapsed since charging of the estimated battery was completed, after the parameter acquisition unit 16c acquires the OCV (predetermined parameter) of the estimated battery at timing t54. With this configuration, even if a travel request is input between the start and end of charging of the estimated battery, the OCV can be acquired after ensuring a predetermined time as a polarization elimination time for the estimated battery. Note that the control unit 16b may not perform the above control if it has not been able to acquire the stabilized pre-charge OCV.

[0076] As shown in FIG. 10 , the power supply system 10 may include a path 22 connecting the positive electrode (positive side) of the first storage battery module 30 to the bus 11, a path 24 connecting the negative electrode (negative side) of the second storage battery module 60 to the bus 12, and a path 23 connecting the path 22 and the path 24. A relay 25 (switch) for connecting and disconnecting the path 22 is provided on the path 22 between a connection point N1 between the path 22 and the path 23 and a connection point N2 between the path 22 and the bus 11. A relay 26 (switch) for connecting and disconnecting the path 23 is provided on the path 23. A relay 27 (switch) for connecting and disconnecting the path 24 is provided on the path 24 between a connection point N3 between the path 24 and the path 23 and a connection point N4 between the path 24 and the bus 12. The relays 25 to 27 are controlled by the ECU 16. The paths 22 to 24 and the relays 25 to 27 form a switching circuit.

[0077] According to the above configuration, the ECU 16 can switch the parallel connection of the first storage battery module 30 and the second storage battery module 60 to the buses 11 and 12 by turning on (connecting) the relays 25 and 27 and turning off (connecting) the relay 26. The ECU 16 can also switch the series connection of the first storage battery module 30 and the second storage battery module 60 to the buses 11 and 12 by turning off (disconnecting) the relays 25 and 27 and turning on (connecting) the relay 26. That is, the switching circuit switches the series connection and parallel connection of the storage battery modules 30 and 60 to the buses 11 and 12. When the switching circuit switches the parallel connection of the storage battery modules 30 and 60, power can be supplied from the storage battery modules 30 and 60 to the buses 11 and 12. This allows the storage battery modules 30 and 60 to be used as redundant power sources. Then, when the storage battery modules 30, 60 are switched to a parallel connection by the switching circuit, the ECU 16 can execute the above-described control of the power supply system 10 and control similar to the modified example. Furthermore, when the storage battery modules 30, 60 are switched to a series connection by the switching circuit, a voltage obtained by adding up the output voltages Vm1, Vm2 of the storage battery modules 30, 60 can be supplied to the buses 11, 12. This allows the storage battery modules 30, 60 to be used as higher-voltage power sources.

[0078] Furthermore, the load 28 may be connected in parallel to the second storage battery 61 (storage battery) of the second storage battery module 60 (storage battery module). In this case, the charge amount of the second storage battery 61 can be reduced by supplying power from the second storage battery 61 to the load 28. This makes it easier to reduce the second output voltage Vb2 of the second storage battery 61 of the second storage battery module 60 to a value lower than the first output voltage Vb1 of the first storage battery 31 of the first storage battery module 30. This makes it easier to perform control to add the second output voltage Vo2 of the second conversion circuit 70 to the second output voltage Vb2 of the second storage battery 61 of the second storage battery module 60, thereby regulating the second output voltage Vm2 of the second storage battery module 60 to the bus voltage request value Vbus*.

[0079] Second Embodiment The second embodiment will be described below, focusing on the differences from the first embodiment. Note that the same parts as those in the first embodiment are denoted by the same reference numerals and the description thereof will be incorporated herein.

[0080] In this embodiment, as shown in FIG. 11 , a power supply system 210 includes three or more storage battery modules 30, 60, and 90. Here, an example will be described in which the power supply system 210 includes three storage battery modules 30, 60, and 90. Note that FIG. 11 shows a simplified representation of the connection of the conversion circuits 40, 70, and 100 (PPCs: Partial Power Converters). The storage battery modules 30, 60, and 90 include voltage sensors 31 a, 61 a, and 91 a that detect the voltages of the storage batteries 31, 61, and 91, respectively, and relays 40 a, 40 b, 70 a, 70 b, 100 a, and 100 b (switches) that connect and disconnect the storage battery modules 30, 60, and 90 to and from the buses 11 and 12, respectively.

[0081] 12 is a flowchart showing the procedure for calculating the full charge capacity according to this embodiment. This series of processes is repeatedly executed by the ECU 16 at a predetermined interval.

[0082] The process of S30 is the same as the process of S10 in FIG. 7 . If it is determined that the timing for starting charging has arrived (S30: YES), the number of non-estimated batteries and estimated batteries is determined (S31). Specifically, the number of batteries to be selected as non-estimated batteries is determined based on the chargeable current (chargeable power) of the power supply system 10. The chargeable current of the power supply system 10 (system) can be, for example, a current upper limit determined by the specifications of the external charger 29 or the specifications of the conversion circuits 40, 70, 100, etc., acquired via communication or the like. The relationship between the chargeable current of the power supply system 10 and the number of batteries to be selected as non-estimated batteries can be specified in advance based on testing or the like (e.g., a table or graph stored in the ECU 16). For example, the larger the chargeable current of the power supply system 10, the greater the number of batteries to be selected as non-estimated batteries. Here, the number of batteries to be selected as non-estimated batteries can also be specified taking into account the chargeable current (chargeable power) of each battery, as described below. Then, the number of storage batteries to be selected as estimated storage batteries is determined by subtracting the number of storage batteries selected as non-estimated storage batteries from the total number N of storage batteries. That is, the number of storage batteries to be selected as estimated storage batteries when charging of the non-estimated storage batteries starts is determined based on the chargeable power (current-carrying capacity) of each storage battery and the chargeable power of the power supply system 10. When the number of storage batteries to be selected as estimated storage batteries has been determined, the method of determining the storage batteries to be preferentially selected as estimated storage batteries is the same as the process of S11 in Fig. 7. Next, charging of all non-estimated storage batteries starts (S32).

[0083] The processes of S33 to S35 are the same as the processes of S13 to S35 in Fig. 7. However, the processes of S34 and S35 are performed for all estimated batteries.

[0084] The processes of S36 and S37 are similar to the processes of S16 and S17 in Fig. 7. However, the processes of S36 and S37 are targeted at all the storage batteries 31, 61, and 91 (all the storage battery modules 30, 60, and 90).

[0085] The process of S38 is the same as the process of S18 in FIG. 7 . However, the process of S38 targets all of the storage batteries 31, 61, 91 (all storage battery modules 30, 60, 90). For example, when charging of the non-estimated storage batteries has started and the estimated storage batteries are left to depolarize, the conversion circuits corresponding to all of the non-estimated storage batteries are controlled to distribute the rated charging power of the external charger 29 to all of the non-estimated storage batteries. When charging of the estimated storage batteries has also started and the non-estimated storage batteries and the estimated storage batteries are being charged, the conversion circuits corresponding to all of the estimated storage batteries and the non-estimated storage batteries are controlled so that the charging time of the estimated storage batteries in response to the connection of the charging cables 29 a, 29 b (charging request) is shorter than the charging time of the non-estimated storage batteries in response to the charging request. When the charging termination conditions for some of the non-estimated storage batteries and some of the estimated storage batteries are met and only some of the non-estimated storage batteries and the estimated storage batteries are being charged, the rated charging power of the external charger 29 is distributed to the part of the batteries being charged.

[0086] Next, it is determined whether the chargeable current of the power supply system 10 is greater than the sum of the chargeable currents of the non-estimated storage batteries (S39). The chargeable current of the non-estimated storage batteries (storage batteries) can be specified in advance based on testing or the like (e.g., a map stored in the ECU 16). For example, the higher the temperature of the storage battery, the greater the chargeable current of the storage battery, and the lower the SOC of the storage battery, the greater the chargeable current. The chargeable current of the storage battery is then calculated by referencing the map and applying the temperature and SOC of the storage battery. If it is determined in this determination that the chargeable current of the power supply system 10 is greater than the sum of the chargeable currents of the non-estimated storage batteries (S39: YES), one of the storage batteries selected as the estimated storage battery is changed to a non-estimated storage battery, and charging is initiated (S40). As shown in FIG. 13 , when charging the non-estimated storage batteries, if the sum of the currents of the non-estimated storage batteries to be charged is significantly smaller than the chargeable current of the power supply system 10 (e.g., the number of non-estimated storage batteries = 1), the charging efficiency of the storage batteries in the power supply system 10 decreases. For example, the charging time required to charge all the non-estimation storage batteries will be longer. Here, the storage batteries cannot be charged with a current greater than the chargeable current of the power supply system 10. If a current greater than the chargeable current of each storage battery is passed through each storage battery, the storage battery will deteriorate. Therefore, the charging current is the smaller of the sum of the chargeable current of the power supply system 10 and the chargeable current of the non-estimation storage batteries. For example, if the number of non-estimation storage batteries is four, the sum of the chargeable currents of the non-estimation storage batteries will be slightly greater than the chargeable current of the power supply system 10. In this case, in the process of S38, the chargeable current of the power supply system 10 is distributed to the four non-estimation storage batteries for charging, thereby improving the charging efficiency of the storage batteries in the power supply system 10. Furthermore, the number of estimated storage batteries (N-4) can be increased as much as possible. If the number of non-estimation storage batteries (N-5) is five, the number of estimated storage batteries (N-5) will be reduced. Therefore, in the process of S40, one of the storage batteries selected as the estimated storage battery is changed to a non-estimation storage battery, and charging begins.

[0087] Next, it is determined whether the voltage difference between the output voltage Vb of the non-estimated battery and the output voltage Vb of the estimated battery is greater than a predetermined voltage difference (S41). If there are multiple non-estimated batteries, the maximum, average, minimum, etc. of the output voltages Vb of the multiple non-estimated batteries can be used as appropriate for this determination. Similarly, if there are multiple estimated batteries, the maximum, average, minimum, etc. of the output voltages Vb of the multiple estimated batteries can be used as appropriate for this determination. The predetermined voltage difference is set to a value that determines whether it will be difficult to adjust the output voltage Vm of the battery module corresponding to the non-estimated battery to match the output voltage Vm of the battery module corresponding to the estimated battery using a conversion circuit. If it is determined in this determination that the voltage difference between the output voltage Vb of the non-estimated battery and the output voltage Vb of the estimated battery is greater than the predetermined voltage difference (S41: YES), the charging power of the battery being charged is adjusted (S42). Specifically, the conversion circuit corresponding to the estimated battery and the conversion circuit corresponding to the non-estimated battery are controlled so as to increase the current amount of power or current input to at least one battery included in the one of the non-estimated battery and the estimated battery with the lower output voltage. For example, the power or current input to the battery with the lowest output voltage included in the one of the non-estimated battery and the estimated battery with the lower output voltage is increased from the current amount. Alternatively, the conversion circuit corresponding to the estimated battery and the conversion circuit corresponding to the non-estimated battery are controlled so as to decrease the current amount of power or current input to at least one battery included in the one of the non-estimated battery and the estimated battery with the higher output voltage. For example, the power or current input to the battery with the highest output voltage included in the one of the non-estimated battery and the estimated battery with the higher output voltage is decreased from the current amount.

[0088] The processing of S43 to S45 is the same as the processing of S19 to S21 in Fig. 7. However, the processing of S43 to S45 targets all estimated batteries.

[0089] The processes of S34, S44, and S45 correspond to the processes performed by the parameter acquisition unit 16c, and the processes of S32, S35, S38, S40, and S42 correspond to the processes performed by the control unit 16b.

[0090] The present embodiment described above in detail has the following advantages in addition to the advantages of the first embodiment.

[0091] When the voltage difference between the output voltage Vb of the non-estimated battery and the output voltage Vb of the estimated battery is greater than a predetermined voltage difference from the start to the end of charging of the multiple storage batteries 31, 61, 91, the control unit 16b controls the conversion circuits corresponding to the estimated storage batteries and the non-estimated storage batteries to reduce the voltage difference. This configuration makes it possible to prevent the voltage difference between the output voltage Vb of the non-estimated storage battery and the output voltage Vb of the estimated storage battery from becoming too large. Therefore, it is possible to maintain a state in which the conversion circuits can adjust the output voltage Vm of the storage battery module corresponding to the non-estimated storage battery to match the output voltage Vm of the storage battery module corresponding to the estimated storage battery.

[0092] The control unit 16b determines the number of storage batteries to be selected as estimated storage batteries when charging of the non-estimated storage batteries starts, based on the chargeable power of each storage battery and the chargeable power of the power supply system 10. With this configuration, the number of non-estimated storage batteries to be charged can be determined taking into account the chargeable power of each storage battery and the chargeable power of the power supply system 10. Therefore, a decrease in the charging efficiency of the power supply system 10 can be suppressed.

[0093] If the chargeable current of the power supply system 10 is greater than the sum of the chargeable currents of all the non-estimated batteries between the start of charging of all the non-estimated batteries and the start of charging of the estimated battery, the control unit 16b changes one of the batteries selected as the estimated battery at the start of charging of the non-estimated batteries to the non-estimated battery and starts charging it. With this configuration, if the chargeable current of the power supply system 10 does not reach the chargeable current of the power supply system 10 even when all the non-estimated batteries are charged, the total charging current of the non-estimated batteries can be increased. Therefore, even if too many batteries are selected as estimated batteries at the start of charging of the non-estimated batteries, a decrease in the charging efficiency of the power supply system 10 can be suppressed.

[0094] The second embodiment can be modified as follows: The same parts as those in the first and second embodiments are denoted by the same reference numerals and the description thereof will be incorporated herein.

[0095] The process of S31 in FIG. 12 may be executed before the series of processes in FIG. 12 is started.

[0096] In the processing of S38 in FIG. 12, when charging of the non-estimated storage batteries has started and the estimated storage batteries have been left to depolarize, if the non-estimated storage batteries include uncharged storage batteries, charging of one of the uncharged non-estimated storage batteries may be started instead of processing of S40.

[0097] As shown in FIG. 14 , the power supply system 210 may include a path 211 connecting a connection point N7 between the third conversion circuit 100 of the third storage battery module 90 and the relay 100a and a connection point N8 between the first storage battery 31 of the first storage battery module 30 and the relay 40b. Furthermore, the power supply system 210 may include a path 213 connecting a connection point N9 between the first conversion circuit 40 of the first storage battery module 30 and the relay 40a and a connection point N10 between the second storage battery 61 of the second storage battery module 60 and the relay 70b. The path 211 is provided with a relay 212 (switch) that connects and disconnects the path 211. The path 213 is provided with a relay 214 (switch) that connects and disconnects the path 213. The relays 212 and 214 are controlled by the ECU 16. The paths 211, 213, and the relays 212 and 214 form a switching circuit. That is, the power supply system 210 may include three or more storage battery modules (plurality of storage battery modules), and the switching circuit may switch the three or more storage battery modules between series connection and parallel connection with the buses 11 and 12 .

[0098] The first and second embodiments can also be modified as follows: The same parts as those in the first and second embodiments are denoted by the same reference numerals and the description thereof will be incorporated herein.

[0099] To determine whether the charging termination condition is met, a voltage threshold value (e.g., corresponding to a predetermined SOC) lower than the full charge voltage threshold value may be used.

[0100] As the load 21, for example, two or more combinations of an inverter and an MG (Motor Generator) (motor units with inverters) may be connected in parallel to the buses 11 and 12. In this case, the more motor units with inverters there are, the more storage battery modules may be connected to the buses 11 and 12.

[0101] As shown in Fig. 15, in the first conversion circuit 40 (conversion circuit), the switching elements 54 and 55 in Fig. 2 may be connected between the transformer 53 and the negative terminal 48. With this configuration, it is possible to achieve the same effects as the first conversion circuit 40 in Fig. 2. The same applies to the second conversion circuit 70 and the third conversion circuit 100 (conversion circuits).

[0102] 16, the first conversion circuit 40 (conversion circuit) may be a well-known isolated DC-DC converter including a non-center-tapped transformer 153 and a secondary-side full-bridge circuit composed of switching elements 143 to 146. The switching elements 143 to 146 are, for example, MOSFETs or IGBTs (Insulated Gate Bipolar Transistors). The switching elements 143 to 146 are controlled by the ECU 16. The same applies to the second conversion circuit 70 and the third conversion circuit 100 (conversion circuits).

[0103] A resonant DC-DC converter may be used as the first conversion circuit 40 (conversion circuit). Also, a non-isolated DC-DC converter such as a buck converter may be used as the first conversion circuit 40 (conversion circuit). The same applies to the second conversion circuit 70 and the third conversion circuit 100 (conversion circuit).

[0104] The storage battery modules 30, 60 may be configured as shown in FIG. 17 . That is, the positive electrode of the first storage battery 31 is connected to the bus 11. The positive electrode of the first storage battery 31 is connected to the primary-side positive terminal 41 of the first conversion circuit 40, and the negative electrode of the first storage battery 31 is connected to the primary-side negative terminal 42 of the first conversion circuit 40. The negative electrode of the first storage battery 31 is connected to the secondary-side positive terminal 47 of the first conversion circuit 40. The secondary-side negative terminal 48 of the first conversion circuit 40 is connected to the bus 12. In this case, too, the positive and negative electrodes of the first storage battery 31 are connected to the primary-side terminal pair 41, 42 of the first conversion circuit 40, respectively, and the first storage battery 31 is connected in series to the secondary-side terminal pair 47, 48 of the first conversion circuit 40. With this configuration, the same effects as those of the above embodiment can be achieved. The same applies to the second storage battery module 60, the third storage battery module 90, etc. (storage battery modules).

[0105] 18 , a general DC-DC converter other than a PPC (partial boost converter) can be used as the conversion circuits 240, 270. The secondary terminal 48 of the conversion circuit 240 is connected to the negative electrode of the first storage battery 31. That is, the first storage battery 31 may be connected in parallel to the pair of secondary terminals 47, 48 of the first conversion circuit 40. The same applies to the second storage battery module 60, the third storage battery module 90, etc. (storage battery modules).

[0106] The parameter acquisition unit 16c can also acquire the OCV (predetermined parameter) and SOC (predetermined parameter) used to estimate the full charge capacity of the estimated battery before and after discharging (energizing) the estimated battery. As shown in FIG. 19 , when a travel request (a request to discharge multiple batteries) is input at timing t61, the control unit 16b starts travelling of the vehicle by discharging at least one of the non-estimated batteries. Meanwhile, at timing t62, a predetermined time after the input of the travel request, the control unit 16b acquires the pre-discharge OCV of the estimated battery using the parameter acquisition unit 16c and then starts discharging. The control unit 16b controls the conversion circuits corresponding to the estimated batteries and the non-estimated batteries so that the discharge time Te2 of the estimated battery in response to the travel request is shorter than the discharge time Te1 of the non-estimated battery in response to the discharge request. When the voltage of the estimated battery is stabilized at timing t64, the parameter acquisition unit 16c acquires the post-discharge OCV of the estimated battery. The parameter acquisition unit 16c then calculates the pre-discharge SOC and the post-discharge SOC by applying the pre-discharge OCV and the post-discharge OCV to the graph in Figure 4. The parameter acquisition unit 16c (ECU 16) then calculates the full charge capacity using the formula: full charge capacity [Ah] = discharge amount x 100 / (pre-discharge SOC - post-discharge SOC). The discharge amount is the integrated value of the current from the start to the end of discharge. Even with this configuration, it is possible to achieve the same effects as the first and second embodiments and their modifications.

[0107] At least one of the functions of the bus voltage setting unit 16 a, the control unit 16 b, and the parameter acquisition unit 16 c of the ECU 16 can be realized by, for example, a battery management unit (BMU) provided for each storage battery to manage the state of the storage battery, a power control electronic control unit (ECU) that controls the power of the electric vehicle, or a vehicle control ECU (host ECU) that controls the electric vehicle overall. Furthermore, when the power supply system 10, 210 is used as, for example, a stationary power source, the functions of the bus voltage setting unit 16 a, the control unit 16 b, and the parameter acquisition unit 16 c of the ECU 16 can be realized by a stationary power source control ECU (control device) that controls the stationary power source.

[0108] The ECU 16 and the methods described herein may be implemented by a special-purpose computer configured with a processor and memory programmed to execute one or more functions (instructions) embodied in a computer program. Alternatively, the ECU 16 and the methods described herein may be implemented by a special-purpose computer configured with a processor implemented by one or more dedicated hardware logic circuits. Alternatively, the ECU 16 and the methods described herein may be implemented by one or more special-purpose computers configured with a processor and memory programmed to execute one or more functions and a processor implemented by one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by a computer on a computer-readable non-transitory storage medium.

[0109] The above-described embodiment and modifications may be combined within the scope of possible combinations.

[0110] Characteristic configurations extracted from the above-described embodiment and modified examples will be described below. [Configuration 1] A storage battery monitoring system (10, 210) in which a plurality of storage battery modules (30, 60, 90) including a storage battery (31, 61, 91) and a conversion circuit (40, 70, 100) that converts power input from the storage battery to a pair of primary terminals (41, 42, 71, 72) and outputs the converted power from a pair of secondary terminals (47, 48, 77, 78) are connected in parallel to at least one of a charging device (29) and a load (21), the system comprising: a parameter acquisition unit (16c, 31a, 51, 61a, 91a) that acquires predetermined parameters used for estimating a full charge capacity of an estimated storage battery before and after energization of the estimated storage battery, which is the storage battery whose full charge capacity is to be estimated; and a control unit (16b) that controls the conversion circuits of the plurality of storage battery modules, respectively, to control energization states of the storage batteries of the plurality of storage battery modules, and a control unit that controls the conversion circuit corresponding to the estimated battery and the conversion circuit corresponding to the non-estimated battery so that a time during which it can be considered that no current is flowing through the estimated battery is equal to or longer than the predetermined time, and the control unit controls the conversion circuit corresponding to the estimated battery and the non-estimated battery so that a time during which it can be considered that no current is flowing through the estimated battery is equal to or longer than the predetermined time, and the control unit controls the conversion circuit corresponding to the estimated battery and the non-estimated battery so that a time during which it can be considered that no current is flowing through the estimated battery is equal to or longer than the predetermined time, and the control unit controls the conversion circuit corresponding to the non-estimated battery[Configuration 3] The storage battery monitoring system according to Configuration 1 or 2, wherein the plurality of storage battery modules are connected in parallel to the charging device, the request for energization for the plurality of storage batteries is a request for charging the plurality of storage batteries, and the control unit controls the conversion circuit corresponding to the estimated storage battery and the conversion circuit corresponding to the non-estimated storage battery so that the charging time of the estimated storage battery in response to the charge request is shorter than the charging time of the non-estimated storage battery in response to the charge request, thereby making an average value of current flowing through the estimated storage battery greater than an average value of current flowing through the non-estimated storage battery from the start to the end of charging of the plurality of storage batteries. [Configuration 4] The storage battery monitoring system according to Configuration 3, wherein the control unit controls the conversion circuit corresponding to the estimated storage battery and the conversion circuit corresponding to the non-estimated storage battery to make the charging end timing of the estimated storage battery earlier than the charging end timing of the non-estimated storage battery. [Configuration 5] The battery monitoring system of Configuration 3 or 4, wherein the positive and negative electrodes of the storage batteries are respectively connected to the primary terminal pair of the conversion circuit, and the storage batteries are connected in series to the secondary terminal pair of the conversion circuit. [Configuration 6] The battery monitoring system of Configuration 5, wherein the control unit controls the conversion circuit corresponding to the estimated storage battery so as to bring the current flowing to the estimated storage battery close to zero from the start of charging of at least one of the non-estimated storage batteries until the start of charging of the estimated storage battery. [Configuration 7] The battery monitoring system of Configuration 5 or 6, wherein the control unit controls the conversion circuit corresponding to the estimated storage battery and the conversion circuit corresponding to the non-estimated storage battery so that the voltage applied to the estimated storage battery from the conversion circuit corresponding to the estimated storage battery is higher than the voltage applied to the non-estimated storage battery from the conversion circuit corresponding to the non-estimated storage battery from the start of charging of the estimated storage battery to the end of charging.[Configuration 8] The battery monitoring system of any one of Configurations 5 to 7, wherein the control unit controls the conversion circuit corresponding to the estimated battery and the conversion circuit corresponding to the non-estimated battery so as to increase, from a current level, the power or current input to at least one battery included in the non-estimated battery or the estimated battery, which has a lower output voltage, or to decrease, from a current level, the power or current input to at least one battery included in the non-estimated battery or the estimated battery, which has a higher output voltage, when a voltage difference between the output voltage of the non-estimated battery and the output voltage of the estimated battery is greater than a predetermined voltage difference from the start to the end of charging of the plurality of batteries. [Configuration 9] The battery monitoring system of any one of Configurations 1 to 8, wherein the control unit controls the conversion circuit corresponding to the estimated battery and the conversion circuit corresponding to the non-estimated battery, when a voltage difference between the output voltage of the non-estimated battery and the output voltage of the estimated battery is greater than a predetermined voltage difference from the start to the end of charging of the plurality of batteries. [Configuration 10] The battery monitoring system of any one of Configurations 1 to 9, wherein the control unit determines the number of batteries to select as the estimated batteries when energization of the non-estimated batteries begins, based on the power that can be supplied to each battery and the power that can be supplied to the battery monitoring system. [Configuration 11] The battery monitoring system of Configuration 10, wherein the control unit changes at least one of the batteries selected as the estimated batteries when energization of the non-estimated batteries begins to begin to the non-estimated battery, and begins energizing the non-estimated battery, if the power that can be supplied to the battery monitoring system is greater than the total power that can be supplied to all of the non-estimated batteries during the period from when energization of all of the non-estimated batteries begins to begin to begin. [Configuration 12] The storage battery monitoring system according to any one of configurations 1 to 11, wherein the control unit terminates energization of the estimated storage battery when a next energization request for the plurality of storage batteries is input between the start and end of energization of the estimated storage battery, and starts energization after the predetermined time has elapsed since the end of energization of the estimated storage battery and the predetermined parameter is acquired in the estimated storage battery by the parameter acquisition unit.

[0111] Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and equivalent modifications. In addition, various combinations and forms, including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure.

Claims

1. A storage battery monitoring system (10, 210) in which a storage battery module (30, 60, 90) including a storage battery (31, 61, 91) and a conversion circuit (40, 70, 100) that converts power input from the storage battery to a primary terminal pair (41, 42, 71, 72) and outputs the power from a secondary terminal pair (47, 48, 77, 78) is connected in parallel to at least one of a charging device (29) and a load (21), the system comprising: a parameter acquisition unit (16c, 31a, 51, 61a, 91a) that acquires predetermined parameters used for estimating a full charge capacity of an estimated storage battery before and after energization of the estimated storage battery, which is the storage battery whose full charge capacity is to be estimated; and a control unit (16b) that controls the conversion circuits of the plurality of storage battery modules, respectively, to control the energization states of the storage batteries of the plurality of storage battery modules, The control unit, when a request for power supply to a plurality of the storage batteries is input, starts power supply to at least one of the non-estimation storage batteries, which are storage batteries whose full charge capacity is not estimated, while starting power supply to the estimated storage battery after a predetermined time has elapsed since the request for power supply was input and after the predetermined parameters have been acquired in the estimated storage battery by the parameter acquisition unit, and controls the conversion circuit corresponding to the estimated storage battery and the conversion circuit corresponding to the non-estimation storage battery so that the power supply time of the estimated storage battery in response to the power supply request is shorter than the power supply time of the non-estimation storage battery in response to the power supply request.

2. The battery monitoring system of claim 1, wherein the specified parameter is an open circuit voltage of the estimated battery measured when the time during which it can be assumed that no current is flowing through the estimated battery is equal to or longer than the specified time, or a charging rate of the estimated battery calculated based on the open circuit voltage.

3. The battery monitoring system of claim 1 or 2, wherein the multiple storage battery modules are connected in parallel to the charging device, the request for current to the multiple storage batteries is a charging request for the multiple storage batteries, and the control unit controls the conversion circuit corresponding to the estimated storage battery and the conversion circuit corresponding to the non-estimated storage battery so that the charging time of the estimated storage battery in response to the charging request is shorter than the charging time of the non-estimated storage battery in response to the charging request, thereby making the average value of the current flowing through the estimated storage battery greater than the average value of the current flowing through the non-estimated storage battery from the start of charging to the end of charging of the multiple storage batteries.

4. The battery monitoring system of claim 3, wherein the control unit controls the conversion circuit corresponding to the estimated battery and the conversion circuit corresponding to the non-estimated battery to make the charging end timing of the estimated battery earlier than the charging end timing of the non-estimated battery.

5. A battery monitoring system as described in claim 3, wherein the positive and negative terminals of the storage battery are respectively connected to the primary terminal pair of the conversion circuit, and the storage battery is connected in series to the secondary terminal pair of the conversion circuit.

6. The battery monitoring system of claim 5, wherein the control unit controls the conversion circuit corresponding to the estimated battery so as to bring the current flowing through the estimated battery closer to zero from the time charging of at least one of the non-estimated batteries is started until charging of the estimated battery is started.

7. The battery monitoring system of claim 5, wherein the control unit controls the conversion circuit corresponding to the estimated battery and the conversion circuit corresponding to the non-estimated battery so that the voltage applied from the conversion circuit corresponding to the estimated battery to the estimated battery is higher than the voltage applied from the conversion circuit corresponding to the non-estimated battery to the non-estimated battery from the start of charging of the estimated battery to the end of charging.

8. The battery monitoring system of claim 5, wherein the control unit controls the conversion circuit corresponding to the estimated battery and the conversion circuit corresponding to the non-estimated battery so as to increase the power or current input to at least one battery among the non-estimated battery and the estimated battery having the lower output voltage from the current level, or to decrease the power or current input to at least one battery among the non-estimated battery and the estimated battery having the higher output voltage from the current level, when a voltage difference between the output voltage of the non-estimated battery and the output voltage of the estimated battery is greater than a predetermined voltage difference from the start of charging to the end of charging of the multiple storage batteries.

9. A battery monitoring system as described in claim 1 or 2, wherein the control unit selects as the estimated battery at least one of the storage batteries that is predicted to be the most deteriorated among the plurality of storage batteries and the storage battery that has not had its full charge capacity calculated for the longest period among the plurality of storage batteries.

10. A battery monitoring system as described in claim 1 or 2, wherein the control unit determines the number of batteries to be selected as the estimated batteries when power supply to the non-estimated batteries begins based on the available power of each battery and the available power of the battery monitoring system.

11. The battery monitoring system of claim 10, wherein the control unit changes at least one of the batteries selected as the estimated battery at the time when power supply to the non-estimated battery is started to the non-estimated battery and starts power supply when the available power of the battery monitoring system is greater than the sum of the available power of all of the non-estimated batteries between the time when power supply to all of the non-estimated batteries is started to the time when power supply to the estimated battery is started to the non-estimated battery.

12. A battery monitoring system as described in claim 1 or 2, wherein the control unit terminates energization of the estimated battery when a next energization request for multiple storage batteries is input between the start and end of energization of the estimated battery, and initiates energization after the specified time has elapsed since the end of energization of the estimated battery, and after the specified parameters are acquired in the estimated battery by the parameter acquisition unit.

13. A control program applied to a storage battery monitoring system (10) in which a storage battery module (30, 60, 90) including a storage battery (31, 61, 91) and a conversion circuit (40, 70, 100) that converts power input from the storage battery to a primary terminal pair (41, 42, 71, 72) and outputs the power from a secondary terminal pair (47, 48, 77, 78) is connected in parallel to at least one of a charging device (29) and a load (21), the control program comprising: a process of acquiring, before the start of current supply to an estimated storage battery, which is the storage battery whose full charge capacity is to be estimated, and after the end of current supply to the estimated storage battery; a process of controlling the current supply states of the storage batteries of the multiple storage battery modules by controlling the conversion circuits of the multiple storage battery modules, respectively; a control program that causes a computer (16) to execute the following process: when a request for energization of a plurality of the storage batteries is input, energization is started for at least one non-estimation storage battery, which is a storage battery for which a full charge capacity is not estimated, while starting energization after a predetermined time has elapsed since the input of the request for energization and after the predetermined parameters have been acquired in the estimated storage battery, and controlling the conversion circuit corresponding to the estimated storage battery and the conversion circuit corresponding to the non-estimation storage battery so that the energization time of the estimated storage battery in response to the request for energization is shorter than the energization time of the non-estimation storage battery in response to the request for energization.

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