Management device and power supply system

Abstract

A management device (30) manages a plurality of power storage modules (M1) connected to a load (60), each power storage module (M1) being connected in parallel via a switch (RY1). In a state in which the switches (RY1) connected to some of the plurality of power storage modules (M1) are turned on and the switches (RY1) connected to the remaining power storage modules (M1) are turned off, when at least one of the switches (RY1) in the off state is to be turned on, and when an upper limit value of a current or power allowed to be discharged from the plurality of power storage modules (M1) as a whole in a case where the switch (RY1) is turned on is lower than a first threshold value based on a maximum value of a current or power required by the load (60), a determination section (313) of the management device (30) does not allow the switch (RY1) to be turned on.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a management device and a power supply system for managing a plurality of power storage modules connected in parallel and to a load. BACKGROUND

[0002] In recent years, electric motorcycles, electric golf carts, electric land cars, forklifts, and the like, which are electric vehicles with low output (for example, 48 V drive), have gradually become widespread. In such electric vehicles, there are electric vehicles that employ a power supply system in which a plurality of detachable and replaceable battery packs are connected in parallel. In the case where a plurality of battery packs are connected in parallel, it is possible that cross current occurs.

[0003] A control is proposed that makes it possible to prevent an excessive rated current from flowing in the battery pack and the relay due to cross current when connecting the disassociated battery packs in parallel (for example, refer to Patent Literature 1). In addition, a control is proposed that estimates a transient voltage at the time of disconnection between the battery packs connected in parallel, and disconnects the relay when the rated voltage of the relay is about to be exceeded (for example, refer to Patent Literature 2).

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: Japanese Patent Application Publication No. 2009-33936

[0007] Patent Literature 2: International Publication No. 2012 / 164630 SUMMARY

[0008] PROBLEMS TO BE SOLVED BY THE INVENTION

[0009] At the time of discharging, when the disassociated battery packs are connected in parallel, the upper limit value of the current or the power allowed to be discharged from the entire parallel system is generally increased. However, due to cross current generated by the parallel connection, the upper limit value of the current or the power allowed to be discharged from the entire parallel system is sometimes decreased compared to before the parallel connection. Due to this decrease in the upper limit value, there are cases where adverse effects such as a decrease in the acceleration performance of the electric vehicle occur.

[0010] At the time of charging, when the disassociated battery packs are connected in parallel, the upper limit value of the current or the power allowed to be charged to the entire parallel system is generally increased. However, due to cross current generated by the parallel connection, the upper limit value of the current or the power allowed to be charged to the entire parallel system is sometimes decreased compared to before the parallel connection. Due to this decrease in the upper limit value, there are cases where adverse effects such as an increase in the charging time and a decrease in the regenerative braking force occur.

[0011] The present disclosure was achieved in view of such circumstances, and aims to provide a technology for preventing an insufficient state of current supplied from a parallel system to a load. In addition, the present disclosure aims to provide a technology for preventing a decrease in charging efficiency when charging a parallel system.

[0012] Solution to the problem

[0013] To solve the above problem, a management device according to an aspect of the present disclosure is used to manage a plurality of power storage modules connected to a load, each of the power storage modules being connected in parallel via a switch, and the management device includes a determination section that, in a state where a switch connected to a part of the plurality of power storage modules is turned on and a switch connected to the remaining power storage modules is turned off, when at least one of the switches in the off state is to be turned on, does not allow the turning on of the switch in a case where an upper limit value of current or power allowed to discharge from the plurality of power storage modules as a whole in a case where the switch is turned on is lower than a first threshold value based on a maximum value of current or power required by the load.

[0014] Another aspect of the present disclosure is a management device. The device is used to manage a plurality of power storage modules connected to a power source, each of the power storage modules being connected in parallel via a switch, and the management device includes a determination section that, in a state where a switch connected to a part of the plurality of power storage modules is turned on and a switch connected to the remaining power storage modules is turned off, when at least one of the switches in the off state is to be turned on, does not allow the turning on of the switch in a case where an upper limit value of current or power allowed to charge the plurality of power storage modules as a whole in a case where the switch is turned on is lower than a third threshold value based on a maximum value of current or power that the power source can output.

[0015] Effects of the invention

[0016] According to the present disclosure, it is possible to prevent an insufficient state of current supplied from a parallel system to a load. In addition, it is possible to prevent a decrease in charging efficiency when charging a parallel system. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a view for explaining an electric vehicle on which a power supply system according to an embodiment is mounted.

[0018] Figure 2 is a view for explaining a battery pack according to Figure 1

[0019] Figure 3 is a view for explaining an internal structure example of a management section according to Figure 1

[0020] is a view for explaining an internal structure example of a management section according to​Figure 4 is a graph showing an example of the SOC-discharge upper limit power characteristic of a certain battery pack at 0°C.

[0021] Figure 5 is a graph showing an example of the SOC-charge upper limit current characteristic of a certain battery pack at 0°C.

[0022] Figure 6 is a graph for explaining cross current between battery packs during discharge.

[0023] Figure 7 is a flowchart for explaining the determination process of parallel connection involved in Embodiment 1.

[0024] Figure 8 is a flowchart for explaining the determination process of parallel connection involved in the application example of Embodiment 1.

[0025] Figure 9 is a graph for explaining cross current between battery packs and convergence of OCV during discharge.

[0026] Figure 10 is a graph for explaining a change example of the discharge upper limit power value of the entire parallel system before and after connecting the unconnected battery pack during discharge.

[0027] Figure 11 is a flowchart for explaining the determination process of parallel connection involved in Embodiment 2.

[0028] Figure 12 is a flowchart for explaining the determination process of parallel connection involved in the modified example of Embodiment 2.

[0029] Figure 13 is a graph for explaining cross current between battery packs during charge.

[0030] Figure 14 is a flowchart for explaining the determination process of parallel connection involved in Embodiment 3.

[0031] Figure 15 is a flowchart for explaining the determination process of parallel connection involved in the application example of Embodiment 3.

[0032] Figure 16 is a graph for explaining cross current between battery packs and convergence of OCV during charge.

[0033] Figure 17 is a graph for explaining a change example of the charge upper limit current value of the entire parallel system before and after connecting the unconnected battery pack during charge.

[0034] Figure 18is a flowchart for explaining the determination processing of the parallel connection involved in Embodiment 4.

[0035] Figure 19 is a flowchart for explaining the determination processing of the parallel connection involved in the modification of Embodiment 4. DETAILED DESCRIPTION

[0036] Figure 1 is a diagram for explaining an electric vehicle 1 equipped with the power supply system 10 involved in the embodiments. The electric vehicle 1 is an electric vehicle using a replaceable battery pack 20 as a power supply, such as an electric motorcycle, an electric golf cart, an electric land vehicle, a forklift, and the like. The battery pack 20 is a movable and replaceable battery pack which is detachably attached to the electric vehicle 1 by a user.

[0037] The power supply system 10 is connected to the motor 60 via a main relay RYc and an inverter 50. At the time of motoring, the inverter 50 converts the direct-current electric power supplied from the power supply system 10 into alternating-current electric power and supplies it to the motor 60. At the time of regeneration, the alternating-current electric power supplied from the motor 60 is converted into direct-current electric power and supplied to the power supply system 10. The motor 60 is a three-phase alternating-current motor which rotates in accordance with the alternating-current electric power supplied from the inverter 50 at the time of motoring. At the time of regeneration, the rotational energy generated due to deceleration is converted into alternating-current electric power and supplied to the inverter 50.

[0038] The vehicle ECU (Electronic Control Unit) 40 is a control device which controls the entire electric vehicle 1. The main relay RYc is a contactor which is interposed between the wiring connecting the power supply system 10 and the inverter 50. At the time of running of the electric vehicle 1, the vehicle ECU 40 controls the main relay RYc to an on state (closed state) to electrically connect the power supply system 10 and the power system of the electric vehicle 1. At the time of non-running of the electric vehicle 1, the vehicle ECU 40 controls the main relay RYc to an off state (open state) to electrically disconnect the power supply system 10 and the power system of the electric vehicle 1. In addition, other kinds of switches such as semiconductor switches can be used instead of relays.

[0039] The electric vehicle 1 is connectable to the charger 2 via a charging cable 5. The charger 2 is connectable to a commercial power system (hereinafter, referred to as a system 3) to charge the battery pack 20 in the power supply system 10 from the outside of the electric vehicle 1. In the case where the charger 2 is a normal charger, the battery pack 20 is generally charged with single-phase 100 / 200 V alternating-current electric power. In this case, the charger 2 and the battery pack 20 are connected via the charging cable 5, an external charging relay RYo, and an AC / DC converter 70.

[0040] The vehicle ECU 40 controls the external charging relay RYo to be in the on state when charging from the charger 2. Also, another kind of switch such as a semiconductor switch can be used instead of a relay. The AC / DC converter 70 includes a rectifier circuit and a DC / DC converter. The rectifier circuit rectifies the alternating-current electric power supplied from the charger 2 to generate direct-current electric power. The DC / DC converter controls the current or voltage of the direct-current electric power generated by the rectifier circuit according to a current command value or a voltage command value specified by the vehicle ECU 40. Thereby, constant current (CC) charging or constant voltage (CV) charging can be performed.

[0041] In a case where the charger 2 is a quick charger, the charger 2 rectifies the alternating-current electric power supplied from the system 3 to generate direct-current electric power. As a quick charging standard, for example, CHAdeMO (registered trademark), GB / T, Combo (Combined Charging System), or the like can be used.

[0042] In the charging cable 5 corresponding to quick charging, a communication line is included in addition to a power line. The vehicle ECU 40 can transmit a current command value or a voltage command value to the charger 2 via the communication line. The charger 2 controls the current or voltage of the direct-current electric power to be output according to the current command value or the voltage command value received from the vehicle ECU 40. In this case, the AC / DC converter 70 in the electric vehicle 1 is bypassed. Also, only the rectifier circuit of the AC / DC converter 70 can be bypassed, and the current or voltage of the direct-current electric power is not controlled on the charger 2 side but by the DC / DC converter in the AC / DC converter 70.

[0043] Figure 1 The example shown is an example in which the battery pack 20 is charged in a state where the battery pack 20 is mounted to the electric vehicle 1. In this regard, charging can also be performed in a state where the battery pack 20 is separated from the electric vehicle 1. In this case, the battery pack 20 can be charged by mounting the battery pack 20 to a charging stand outside the electric vehicle 1.

[0044] The power supply system 10 includes the management unit 30 and a plurality of battery packs 20a-20c. The plurality of battery packs 20a-20c are connected in parallel and connected to the load (mainly the motor 60) of the electric vehicle 1. Also, at the time of regeneration, the motor 60 becomes a power supply of the plurality of battery packs 20a-20c. The number of the battery packs 20 connected in parallel is determined according to the required capacity or the required output of the electric vehicle 1. In the example shown in FIG. 1, three battery packs 20a-20c are connected in parallel, but the number of the battery packs 20 connected in parallel is not limited to three. More battery packs 20 can be connected in parallel to extend the cruising distance. Also, in a case where the electric vehicle 1 is small, two battery packs 20 can be connected in parallel. Figure 1 In the example shown in FIG. 1, three battery packs 20a-20c are connected in parallel, but the number of the battery packs 20 connected in parallel is not limited to three. More battery packs 20 can be connected in parallel to extend the cruising distance. Also, in a case where the electric vehicle 1 is small, two battery packs 20 can be connected in parallel.

[0045] Figure 2 is a diagram showing Figure 1 an example of an internal structure of the battery pack 20. The battery pack 20 includes a battery pack relay RY1, a relay drive section 25, a battery module M1, a shunt resistor Rs, temperature sensors T1, T2, a voltage measurement section 21, a temperature measurement section 22, a current measurement section 23, and a control section 24. The relay drive section 25 turns on / off the battery pack relay RY1 in accordance with a control signal received from the management section 30 via the control section 24.

[0046] The battery module M1 includes a plurality of cells E1-En connected in series. The battery module M1 can also be configured by connecting a plurality of cell blocks in series, the cell blocks being configured by a plurality of cells connected in parallel. The cells can use lithium ion cells, nickel-hydrogen cells, lead cells, or the like. Hereinafter, in the present specification, an example in which lithium ion cells (nominal voltage: 3.6 V-3.7 V) are used will be assumed.

[0047] The shunt resistor Rs is connected in series with the plurality of cells E1-En configuring the battery module M1. The shunt resistor Rs functions as a current detection element. In addition, a Hall element can also be used instead of the shunt resistor Rs. Further, a plurality of temperature sensors T1, T2 for detecting the temperature of the plurality of cells E1-En are provided. One temperature sensor or a plurality of temperature sensors can be provided in the battery module M1. The temperature sensors T1, T2 can use, for example, a thermistor.

[0048] A plurality of voltage lines are connected between each node of the plurality of cells E1-En connected in series and the voltage measurement section 21. The voltage measurement section 21 measures the voltage of each cell E1-En by measuring the voltage between adjacent 2 voltage lines, respectively. The voltage measurement section 21 transmits the measured voltage of each cell E1-En to the control section 24 via a communication line.

[0049] The voltage of the voltage measurement section 21 is higher than the voltage of the control section 24, and thus the voltage measurement section 21 and the control section 24 are connected by a communication line in an insulated state as necessary. The voltage measurement section 21 can be configured by an ASIC (Application Specific Integrated Circuit) or a general-purpose analog front-end IC. The voltage measurement section 21 includes a multiplexer and an A / D converter. The multiplexer sequentially outputs the voltage between adjacent 2 voltage lines to the A / D converter in order from top to bottom. The A / D converter converts the analog voltage input from the multiplexer into a digital value.

[0050] The temperature measuring section 22 includes a voltage dividing resistor and an A / D converter. The A / D converter sequentially converts a plurality of analog voltages obtained by voltage division by the plurality of temperature sensors T1, T2 and the plurality of voltage dividing resistors, respectively, into digital values and outputs to the control section 24. The control section 24 estimates the temperatures of the plurality of cells E1-En based on the digital values.

[0051] The current measuring section 23 includes a differential amplifier and an A / D converter. The differential amplifier amplifies the voltage across the shunt resistor Rs and outputs to the A / D converter. The A / D converter converts the analog voltage input from the differential amplifier into a digital value and outputs to the control section 24. The control section 24 estimates the current flowing in the plurality of cells E1-En based on the digital value.

[0052] Further, in a case where the A / D converter is incorporated in the control section 24 and an analog input port is provided to the control section 24, the temperature measuring section 22 and the current measuring section 23 can also output analog voltages to the control section 24, and the analog voltages are converted into digital values by the A / D converter in the control section 24.

[0053] The control section 24 manages the states of the plurality of cells E1-En based on the voltages, temperatures, and currents of the plurality of cells E1-En measured by the voltage measuring section 21, the temperature measuring section 22, and the current measuring section 23. The control section 24 can be constituted by a microcomputer and a nonvolatile memory (for example, an EEPROM (Electrically Erasable Programmable Read-Only Memory), a flash memory).

[0054] The SOC (State Of Charge)-OCV (Open Circuit Voltage) map 241 is retained in the internal memory of the microcomputer. In the SOC-OCV map 241, characteristic data of the SOC-OCV curve of the cell E1-En is described. The SOC-OCV curve of the cell E1-En is prepared in advance based on a characteristic test by a battery manufacturer and is registered in the internal memory of the microcomputer at the time of shipment. Further, the SOC-OCV map 241 can also be registered in the nonvolatile memory. In order to estimate the SOC or the OCV of the cell E1-En with higher accuracy, the battery manufacturer can also derive the SOC-OCV characteristics of the cell E1-En for each combination of the temperature division and the deterioration degree (SOH: State Of Health) division and map them. Further, a function that takes the SOC as a target variable and the OCV, the temperature, and the deterioration degree as explanatory variables can also be used instead of the map.

[0055] The control section 24 can estimate the SOC and SOH of each of the plurality of cells El-En. The control section 24 can estimate the SOC by an OCV method or a current integration method. The OCV method is a method of estimating the SOC based on the OCV of each cell El-En measured by the voltage measurement section 21 and the characteristic data of the SOC-OCV curve described in the SOC-OCV map 241. Further, the OCV at a future time point can be estimated based on the voltage of each cell El-En measured by the voltage measurement section 21, the current of the battery module Ml measured by the current measurement section 23, and the temperature of the battery module Ml measured by the temperature measurement section 22. The current integration method is a method of estimating the SOC based on the OCV at the start of charge and discharge of each cell El-En and the integrated value of the current measured by the current measurement section 23. In the current integration method, the measurement error of the current measurement section 23 accumulates as the charge and discharge time becomes longer. Thus, it is preferable to use the SOC estimated by the OCV method and correct the estimated SOC by the current integration method.

[0056] The SOH is defined as the ratio of the current full charge capacity to the initial full charge capacity, and the lower the value (the closer to 0%), the more the deterioration is severe. The SOH can be found by capacity measurement based on full charge and discharge, or by adding the preservation deterioration and the cycle deterioration. The preservation deterioration can be estimated based on the SOC, the temperature, and the preservation deterioration rate. The cycle deterioration can be estimated based on the SOC range used, the temperature, the current rate, and the cycle deterioration rate. The preservation deterioration rate and the cycle deterioration rate can be derived in advance by experiments, simulations. The SOC, the temperature, the SOC range, and the current rate can be found by measurement.

[0057] In addition, the SOH can also be estimated based on the correlation with the internal resistance of the cell. The internal resistance can be estimated by dividing the voltage drop generated when a prescribed current flows in the cell for a prescribed time by the current value. Regarding the internal resistance, there is a relationship in which the higher the temperature, the lower the internal resistance, and there is a relationship in which the lower the SOH, the higher the internal resistance.

[0058] The control section 24 of the battery pack 20 periodically transmits monitoring data including at least one of the voltage, the temperature, the current, the SOC, the SOH, and the internal resistance of the plurality of cells El-En included in the battery pack 20 to the management section 30. The communication between the control section 24 of the battery pack 20 and the management section 30 can use, for example, serial communication in accordance with the RS-485 standard. The communication between the control section 24 of the battery pack 20 and the management section 30 can be connected by a dedicated communication line, can be connected by wireless, or can be connected by power line communication.

[0059] Figure 3 is a graph showing Figure 1FIG. 1 is a diagram of an internal structure example of a management section 30. The management section 30 includes a processing section 31 and a storage section 32 for managing a plurality of battery packs 20a-20c.

[0060] The processing section 31 includes an acquisition section 311, a calculation section 312, a determination section 313, and a notification section 314. The functions of the processing section 31 can be realized by cooperation of hardware resources and software resources or by hardware resources alone. As the hardware resources, a CPU, a ROM, a RAM, a DSP, an ASIC, an FPGA, and other LSIs can be utilized. As the software resources, a program such as firmware can be utilized.

[0061] The storage section 32 includes a nonvolatile recording medium such as a flash memory. The storage section 32 holds an SOC-discharge upper limit current map 321 and an SOC-charge upper limit current map 322. In the SOC-discharge upper limit current map 321, characteristic data of SOC-discharge upper limit current curves of the cells El-En is described. The SOC-discharge upper limit current curves of the cells El-En are made based on a characteristic test performed by a battery manufacturer. The SOC-discharge upper limit current curves are characteristic data in which an upper limit value of a discharge current allowed to be discharged from a cell is specified for each SOC from the viewpoint of protection and safety of the cell. In a general cell, the lower the SOC, the lower the upper limit value of the current allowed to be discharged.

[0062] In the SOC-charge upper limit current map 322, characteristic data of SOC-charge upper limit current curves of the cells El-En is described. The SOC-charge upper limit current curves of the cells El-En are made based on a characteristic test performed by a battery manufacturer. The SOC-charge upper limit current curves are characteristic data in which an upper limit value of a charge current allowed to be charged to a cell is specified for each SOC from the viewpoint of protection and safety of the cell. In a general cell, the higher the SOC, the lower the upper limit value of the current allowed to be charged. In addition, in the present specification, for the sake of easy understanding of the explanation, it is assumed that both the discharge current and the charge current are absolute values. In practice, the discharge current is generally defined as positive, and the charge current is defined as negative.

[0063] When discharging from a cell, the greater the discharge current, the lower the CCV (Closed Circuit Voltage). The CCV of the cell at the time of discharging is defined by the following (Formula 1). When charging a cell, the greater the charge current, the higher the CCV. The CCV of the cell at the time of charging is defined by the following (Formula 2).

[0064] CCVd = OCV - Id x R... (Formula 1)

[0065] CCVc = OCV + Ic x R... (Formula 2)

[0066] Id is the discharge current, Ic is the charge current, and R is the internal resistance.

[0067] As shown in the above (Formula 1), if the discharge current Id becomes large, the CCV decreases. If the CCV enters the over-discharge region, the burden on the battery becomes large, and this becomes a main cause of deterioration. As shown in the above (Formula 1), the lower the OCV, the lower the CCV. Since the lower the SOC, the lower the OCV, the lower the SOC, it is necessary to set the upper limit value of the discharge current Id lower. As shown in the above (Formula 2), if the charge current Ic becomes large, the CCV increases. If the CCV enters the over-charge region, the burden on the battery becomes large, and this becomes a main cause of deterioration. As shown in the above (Formula 2), the higher the OCV, the higher the CCV. Since the higher the SOC, the higher the OCV, the higher the SOC, it is necessary to set the upper limit value of the charge current Ic lower.

[0068] The SOC-discharge upper limit current characteristic of the single cells E1-En depends on the temperature and the degree of deterioration (SOH). The battery manufacturer derives the SOC-discharge upper limit current characteristic of the single cells E1-En for each combination of the temperature and the degree of deterioration and maps it. The SOC-discharge upper limit current characteristic is registered in the control section 24 of the battery pack 20 (for example, in the internal memory of a microcomputer) at the time of shipment. At the time when the battery pack 20 is initially installed in the electric vehicle 1, the management section 30 of the electric vehicle 1 acquires the SOC-discharge upper limit current characteristic from the control section 24 of the battery pack 20. Further, instead of the SOC-discharge upper limit current characteristic, the SOC-discharge upper limit power characteristic can also be used, and both the SOC-discharge upper limit power characteristic and the SOC-discharge upper limit current characteristic can also be used. In addition, instead of the map, a function in which the discharge upper limit current or the discharge upper limit power is the target variable and the SOC, the temperature, and the degree of deterioration are the explanatory variables can also be used.

[0069] The SOC-charge upper limit current characteristic of the unit cells E1-En also depends on the temperature and the deterioration degree (SOH). The battery manufacturer derives the SOC-charge upper limit current characteristic of the unit cells E1-En for each combination of the temperature and the deterioration degree and maps it. The SOC-charge upper limit current characteristic is registered in the control section 24 of the battery pack 20 (for example, in the internal memory of the microcomputer) at the time of shipment. At the time when the battery pack 20 is initially installed in the electric vehicle 1, the management section 30 of the electric vehicle 1 acquires the SOC-charge upper limit current characteristic from the control section 24 of the battery pack 20. Further, instead of the SOC-charge upper limit current characteristic, the SOC-charge upper limit power characteristic can also be used, or both the SOC-charge upper limit current characteristic and the SOC-charge upper limit power characteristic can be used. For example, it can be that the upper limit value of the charging current from the charger 2 is controlled with reference to the SOC-charge upper limit current characteristic, and the upper limit value of the regenerative electric power from the motor 60 is controlled with reference to the SOC-charge upper limit power characteristic. In addition, instead of the map, a function that takes the charging upper limit current or the charging upper limit power as the argument variable and takes the SOC, the temperature, and the deterioration degree as the explanatory variable can be used.

[0070] Figure 4 is a graph showing an example of the SOC-discharge upper limit power characteristic of a certain battery pack at 0°C. As shown in Figure 4 , the lower the SOC, the lower the discharge upper limit power. Figure 5 is a graph showing an example of the SOC-charge upper limit current characteristic of a certain battery pack at 0°C. As shown in Figure 5 , the higher the SOC, the lower the charge upper limit current.

[0071] Returning to Figure 3 , the acquisition section 311 acquires the monitoring data including at least the voltage and the SOC of the unit cells E1-En from the control section 24 of each battery pack 20. The arithmetic section 312 estimates the SOC of each battery pack 20 based on the SOCs of the plurality of unit cells E1-En included in each battery pack 20. Generally, the SOC of the lowest unit cell is set as the SOC of the battery pack at a low SOC, and the SOC of the highest unit cell is set as the SOC of the battery pack at a high SOC. Further, the arithmetic section 312 can also convert the SOCs of the plurality of unit cells E1-En included in the battery pack 20 into capacities, calculate the total capacity of the plurality of unit cells E1-En, and set the SOC corresponding to the total capacity as the SOC of the battery pack.

[0072] As described above, in the present embodiment, a state in which the battery pack relay RY1 connected to a part of the plurality of battery packs 20a-20c is turned on and the battery pack relay RY1 connected to the remaining battery packs 20 of the plurality of battery packs 20a-20c is turned off occurs.

[0073] When one of the battery pack relays RY1 in the off state (hereinafter referred to as the target battery pack relay RY1) should be turned on at the time of discharging, the operation section 312 estimates an upper limit value of the current or the electric power that is allowed to be discharged from the plurality of battery packs 20 as a whole (hereinafter referred to as the parallel system) in the case where the target battery pack relay RY1 is turned on.

[0074] The determination section 313 compares the upper limit value estimated by the operation section 312 (hereinafter referred to as the predicted upper limit value) with a first threshold value based on the maximum value of the current or the electric power required by the load (mainly the motor 60). The first threshold value can be set to the same value as the maximum value of the current or the electric power required by the load, or can be set to a value lower (condition relaxation) than the maximum value of the current or the electric power required by the load based on past travel data of the electric vehicle 1. For example, according to past travel data, in the case where the electric vehicle 1 travels with the electric power of 80% or less of the maximum value of the electric power required by the load for 95% or more of the travel time of the electric vehicle 1, the vehicle ECU 40 can also set the value of 80% of the maximum value of the electric power required by the load as the above-mentioned first threshold value. The vehicle ECU 40 sets this first threshold value to the management section 30 of the power supply system 10.

[0075] In the case where the predicted upper limit value is the first threshold value or more, the determination section 313 allows the turning on of the target battery pack relay RY1, and in the case where the predicted upper limit value is lower than the first threshold value, the determination section 313 does not allow the turning on of the target battery pack relay RY1. In the case where the determination section 313 allows the turning on of the target battery pack relay RY1, the relay drive section 25 turns on the target battery pack relay RY1.

[0076] In addition, the determination section 313 compares the upper limit value estimated by the operation section 312 (hereinafter referred to as the predicted upper limit value) with a second threshold value based on the upper limit value of the current or the electric power that is allowed to be discharged from the parallel system before the turning on of the target battery pack relay RY1 (hereinafter referred to as the current upper limit value). The second threshold value can be the same value as the current upper limit value (adjustment value a = 0), can be a value obtained by adding the adjustment value a to the current upper limit value, or can be a value obtained by subtracting the adjustment value a from the current upper limit value. The designer can set the adjustment value a in consideration of the number of parallel connections of the battery packs 20, the application program, and the like. In the case where the predicted upper limit value is the second threshold value or more, the determination section 313 allows the turning on of the target battery pack relay RY1, and in the case where the predicted upper limit value is lower than the second threshold value, the determination section 313 does not allow the turning on of the target battery pack relay RY1. In the case where the determination section 313 allows the turning on of the target battery pack relay RY1, the relay drive section 25 turns on the target battery pack relay RY1.

[0077] The notification section 314 notifies the vehicle ECU 40 of an upper limit value of the current or the electric power that is allowed to be discharged from the parallel system (hereinafter referred to as a discharge upper limit current value or a discharge upper limit electric power value of the parallel system as a whole (referred to as a discharge upper limit value in the case of collectively referring to both)). The management section 30 and the vehicle ECU 40 are connected through an in-vehicle network. As the in-vehicle network, for example, a CAN (Controller Area Network), a LIN (Local Interconnect Network) can be used. The vehicle ECU 40 sets the discharge upper limit current value or the discharge upper limit electric power value of the parallel system as a whole, which is received from the management section 30, to the inverter 50. The inverter 50 controls the output current or the output electric power supplied to the motor 60 within the range of the set discharge upper limit current value or the discharge upper limit electric power value.

[0078] At the time of charging, when the subject battery pack relay RY1 should be turned on, the operation section 312 estimates an upper limit value of the current or the electric power that is allowed to charge the parallel system in the case where the subject battery pack relay RY1 is turned on.

[0079] The determination section 313 compares the predicted upper limit value of the current or the electric power that is allowed to charge the parallel system in the case where the subject battery pack relay RY1 is turned on with a third threshold value based on the maximum value of the current or the electric power that can be output by the power supply. In running, the third threshold value can be set to the same value as the maximum value of the current or the electric power that can be regenerated from the motor 60, or can be set to a value lower (condition relaxation) than the maximum value of the current or the electric power that can be regenerated from the motor 60 based on past running data of the electric vehicle 1. For example, according to the past running data, in the case where the regeneration is performed with the electric power of 80% or less of the maximum value of the electric power that can be regenerated from the motor 60 for 95% or more of the total regeneration time of the electric vehicle 1, the vehicle ECU 40 can set a value of 80% of the maximum value of the electric power that can be regenerated from the motor 60 as the above-described third threshold value. During the period of charging from the charger 2, the above-described third threshold value is set to the maximum value of the current or the electric power that can be output by the charger 2.

[0080] In the case where the predicted upper limit value is the third threshold value or more, the determination section 313 allows the turning on of the subject battery pack relay RY1, and in the case where the predicted upper limit value is lower than the third threshold value, the determination section 313 does not allow the turning on of the subject battery pack relay RY1. In the case where the determination section 313 allows the turning on of the subject battery pack relay RY1, the relay drive section 25 turns on the subject battery pack relay RY1.

[0081] Further, the determination section 313 compares the predicted upper limit value with a fourth threshold value based on the current upper limit value before the target battery pack relay RY1 is turned on. The fourth threshold value can be the same value as the current upper limit value (adjustment value a = 0), can be a value obtained by adding the adjustment value a to the current upper limit value, or can be a value obtained by subtracting the adjustment value a from the current upper limit value. The designer can set the adjustment value a in consideration of the number of parallel connections of the battery packs 20, the application program, and the like. In a case where the predicted upper limit value is equal to or higher than the fourth threshold value, the determination section 313 permits the turning on of the target battery pack relay RY1, and in a case where the predicted upper limit value is lower than the fourth threshold value, the determination section 313 does not permit the turning on of the target battery pack relay RY1.

[0082] The notification section 314 notifies the vehicle ECU 40 of the upper limit value of the current or the electric power that is allowed to charge the parallel system (hereinafter referred to as the charging upper limit current value or the charging upper limit electric power value of the parallel system as a whole (referred to as the charging upper limit value in the case where both are collectively referred to)). The vehicle ECU 40 controls the regenerative current or the regenerative electric power regenerated by the motor 60 within the range of the charging upper limit current value or the charging upper limit electric power value of the parallel system as a whole received from the management section 30. For example, when the regenerative electric power value regenerated by the regenerative brake reaches the charging upper limit electric power value of the parallel system as a whole, the vehicle ECU 40 switches from the regenerative brake to the mechanical brake. In the mechanical brake, the regenerative energy is converted into thermal energy. Further, in a case where the quick charging is performed in direct current from the charger 2, the notification section 314 notifies the charger 2 of the charging upper limit current value or the charging upper limit electric power value of the parallel system as a whole.

[0083] Basically, the more the number of parallel connections of the battery packs 20 increases, the more the discharge upper limit value and the charging upper limit value of the parallel system as a whole increase. However, there is a case where the discharge upper limit value and the charging upper limit value of the parallel system as a whole do not increase even if the battery pack 20 is added to the parallel system. This is due to a case where cross current occurs between the plurality of battery packs 20 by connecting the unconnected battery pack 20.

[0084] Figure 6 is a view for explaining cross current between the battery packs 20 during discharging. In Figure 6 In the left side state, the first battery pack relay RY1 connected to the first battery pack 20a is turned on, and the second battery pack relay RY1 connected to the second battery pack 20b is turned off, and only the current is supplied from the first battery pack 20a to the load. In this case, the discharge upper limit current value of the parallel system as a whole coincides with the discharge upper limit current value of the first battery pack 20a.

[0085] Figure 6The state on the right side of FIG. 8 is a view showing a state after the second battery pack relay RYl is turned on. In a case where the OCV of the second battery pack 20b is lower than the CCV in a case where the first battery pack 20a is discharged at the discharge upper limit current value, a cross current occurs from the first battery pack 20a to the second battery pack 20b. Thereby, the current discharged from the first battery pack 20a is shunted to the load and the second battery pack 20b, and the discharge upper limit current value of the system as a whole is reduced. In a case where the motor 60 of the electric vehicle 1 rotates at a current value in the vicinity of the discharge upper limit current value, due to the reduction of the discharge upper limit current value, it is possible that unintended deceleration occurs.

[0086] The CCV in a case where the first battery pack 20a is discharged at the discharge upper limit current value is an estimated value. The current discharged from the first battery pack 20a varies due to load variation, and the CCV of the first battery pack 20a varies according to the variation of the discharge current. The CCV in a case where the first battery pack 20a is discharged at the discharge upper limit current value is a value indicating the lowest voltage at the time of discharge of the first battery pack 20a.

[0087] Next, a case where the second battery pack relay RYl is turned on is considered in a case where the CCV in a case where the first battery pack 20a is discharged at the discharge upper limit current value coincides with the OCV of the second battery pack 20b. In a case where the current actually discharged from the first battery pack 20a to the load coincides with the discharge upper limit current value of the first battery pack 20a, the CCV of the first battery pack 20a is equal to the OCV of the second battery pack 20b. In this case, no cross current occurs between the first battery pack 20a and the second battery pack 20b, and the discharge upper limit current value of the system as a whole is not reduced.

[0088] In a case where the current actually discharged from the first battery pack 20a to the load is lower than the discharge upper limit current value of the first battery pack 20a, the actual CCV of the first battery pack 20a is higher than the CCV in a case where the first battery pack 20a is discharged at the discharge upper limit current value. In this case, a cross current occurs from the first battery pack 20a to the second battery pack 20b. However, in a case where the consumption current of the load rises to the discharge upper limit current value of the first battery pack 20a, the cross current stops, and thus the discharge upper limit current value of the system as a whole is not reduced.

[0089] Next, a case where the second battery pack relay RYl is turned on is considered in a case where the OCV of the second battery pack 20b is higher than the CCV in a case where the first battery pack 20a is discharged at the discharge upper limit current value. Since the discharge upper limit current value of the second battery pack 20b is larger than the discharge upper limit current value of the first battery pack 20a, the discharge upper limit current value of the system as a whole is not reduced at the time when the second battery pack relay RYl is turned on.

[0090] Further, in the above description, an example in which both the discharge upper limit current value of each battery group 20 and the discharge upper limit current value of the parallel system as a whole are calculated by the arithmetic unit 312 of the management unit 30 is described. In this regard, the discharge upper limit current value of the battery group 20 can also be calculated by the control unit 24 within the battery group 20. The control unit 24 within each battery group 20 transmits the calculated discharge upper limit current value of the battery group 20 to the management unit 30. The arithmetic unit 312 of the management unit 30 calculates the discharge upper limit current value of the parallel system as a whole based on the respective discharge upper limit current values received from the plurality of battery groups 20.

[0091] Next, two embodiments of the determination process for determining whether or not to allow the parallel connection of the object battery group relay RY1 during discharging will be described. Embodiment 1 is a dynamic determination process, and Embodiment 2 is a static determination process.

[0092] Figure 7 is a flowchart for explaining the determination process for the parallel connection involved in Embodiment 1. When the power of the electric vehicle 1 is turned on (equivalent to the ignition of an engine vehicle being turned on) (YES in S10), the determination unit 313 causes the relay drive unit 25 to turn on the battery group relay RY1 connected to the battery group 20 having the highest OCV among the plurality of battery groups 20 (S11). In the case where there are a plurality of battery groups 20 having the highest OCV, the determination unit 313 causes a plurality of battery group relays RY1 connected to the plurality of battery groups 20 to be turned on simultaneously.

[0093] During the execution of the parallel connection control (NO in S12), the following process is executed. The determination unit 313 determines the battery group 20 having the highest OCV among the battery groups 20 in which the battery group relay RY1 is in the off state as a connection candidate to which the battery group relay RY1 should be turned on next (S13).

[0094] The arithmetic unit 312 refers to the SOC-discharge upper limit current map 321 based on the SOC of the battery group 20 in which the battery group relay RY1 is in the on state to derive the discharge upper limit current value of the battery group 20. The arithmetic unit 312 applies the OCV, internal resistance, and discharge upper limit current value of the battery group 20 to the above-described (Formula 1) to estimate the CCV corresponding to the discharge upper limit current value of the battery group 20 (S14). Further, in deriving the SOC, internal resistance, and discharge upper limit current value of the battery group 20, the arithmetic unit 312 considers at least the temperature and SOH of the battery group 20 as parameters.

[0095] The arithmetic unit 312 estimates the current value flowing to the battery group 20 as the connection candidate in the case where the CCV of the battery group 20 as the connection candidate and the CCV corresponding to (substantially equal to) the discharge upper limit current value at which the battery group 20 already connected is discharged (S16).

[0096] The value of the current flowing to the load uses the current value. Normally, the value of the current actually flowing in the load is lower than the discharging upper limit current value, and therefore, the CCV of the battery pack 20 that has been connected is higher than the CCV in the case where the battery pack 20 is discharged at the discharging upper limit current value by an amount corresponding to the voltage corresponding to the difference in current. The arithmetic unit 312 calculates the difference voltage between the actual CCV of the battery pack 20 that has been connected and the CCV (= the CCV in the case where the battery pack 20 that has been connected is discharged at the discharging upper limit current value) of the battery pack 20 that is a connection candidate, and estimates the value of the current flowing to the battery pack 20 that is a connection candidate on the basis of the difference voltage and the internal resistance of the battery pack 20 that is a connection candidate. This value of the current is the value of the cross current flowing from the battery pack 20 that has been connected to the battery pack 20 that is a connection candidate.

[0097] The arithmetic unit 312 subtracts the estimated value of the current (the value of the cross current) from the discharging upper limit current value of the parallel connection system as a whole before the connection of the battery pack 20 that is a connection candidate, to estimate the discharging upper limit current value of the parallel connection system as a whole after the connection of the battery pack 20 that is a connection candidate (S17).

[0098] The determination unit 313 compares the estimated discharging upper limit current value after the connection with a threshold value based on the maximum value of the current required by the load (S18). In the case where the discharging upper limit current value after the connection is equal to or higher than the threshold value (YES in S18), the determination unit 313 permits the connection of the battery pack 20 that is a connection candidate (S19), and causes the relay drive unit 25 to turn on the battery pack relay RY1 connected to the battery pack 20 that is a connection candidate. The processing proceeds to step S12. In the case where the discharging upper limit current value after the connection is lower than the threshold value (NO in S18), the determination unit 313 does not permit the connection of the battery pack 20 that is a connection candidate (S110). The processing proceeds to step S12.

[0099] Further, in the case where there are a plurality of battery packs 20 in the on state, the CCVs corresponding to the discharging upper limit current value of the plurality of battery packs 20 are identical. In this state where the CCVs are identical, the arithmetic unit 312 estimates the CCV corresponding to the discharging upper limit current value of the plurality of battery packs 20 in the on state.

[0100] Figure 8 This is a flowchart for explaining the determination processing of the parallel connection involved in the application example of Embodiment 1. Figure 8 The flowchart involved in the application example of Embodiment 1 shown in FIG. 6 is a flowchart obtained by adding the processing of step S15 to the flowchart involved in the basic example of Embodiment 1 shown in FIG. 5. Figure 7 The flowchart involved in the application example of Embodiment 1 shown in FIG. 6 is a flowchart obtained by adding the processing of step S15 to the flowchart involved in the basic example of Embodiment 1 shown in FIG. 5.

[0101] In step S15, the determination section 313 compares the estimated CCV in the case where the already connected battery group 20 is discharged at the discharge upper limit current value with the OCV of the battery group 20 that is the connection candidate (S15). In the case where the estimated CCV is equal to or lower than the OCV of the battery group 20 that is the connection candidate (YES in S15), the determination section 313 permits the connection of the battery group 20 that is the connection candidate (S19), and the relay drive section 25 turns on the battery group relay RY1 connected to the battery group 20 that is the connection candidate. The processing proceeds to step S12. In the case where the estimated CCV in step S15 is higher than the OCV of the battery group 20 that is the connection candidate (NO in S15), the processing proceeds to step S16.

[0102] In the application example, in the case where the estimated CCV in the case where the already connected battery group 20 is discharged at the discharge upper limit current value is equal to or lower than the OCV of the battery group 20 that is the connection candidate, the operation processing of steps S16 to S18 can be skipped, and thus the amount of operation can be reduced.

[0103] Next, Embodiment 2 of the determination processing of parallel connection during discharging will be described. As described above, in the case where the OCVs are not consistent between the plurality of battery groups 20 connected in parallel, cross current occurs from the battery group 20 with a high OCV to the battery group 20 with a low OCV. Due to the cross current, the OCV of the battery group 20 with a high OCV decreases, and the OCV of the battery group 20 with a low OCV increases. When the voltage difference between the two disappears, the cross current stops. In the state where the cross current stops, the OCVs become consistent between the plurality of battery groups 20 connected in parallel.

[0104] Figure 9 is a graph for explaining the cross current between the battery groups 20 during discharging and the convergence of the OCVs. In Figure 9 In the left side state of FIG. 8, the first battery group relay RY1 connected to the first battery group 20a is turned on, and the second battery group relay RY1 connected to the second battery group 20b is turned off, and the OCV of the first battery group 20a is higher than the OCV of the second battery group 20b.

[0105] Figure 9 The right side state of FIG. 8 shows the state after the second battery group relay RY1 is turned on. When the first battery group 20a and the second battery group 20b are connected, current flows from the first battery group 20a to the second battery group 20b, the OCV of the first battery group 20a decreases, and the OCV of the second battery group 20b increases. When the OCVs of the two become consistent after a while, the cross current from the first battery group 20a to the second battery group 20b stops.

[0106] In the ideal condition where the battery pack capacities are uniform, the SOC of the first battery pack 20a and the second battery pack 20b in the state where the cross current is stopped becomes the average of the SOC of the first battery pack 20a before the cross current is generated and the SOC of the second battery pack 20b, and the OCV in the state where the cross current is stopped becomes the OCV corresponding to the average SOC. Further, in the case where three or more battery packs 20 whose OCVs are not uniform are connected in parallel, in the ideal condition, the OCVs of the three or more battery packs 20 become uniform due to the cross current. In this case, the OCV of the three or more battery packs 20 after the OCVs are uniform becomes the average of the OCVs of the three or more battery packs 20 before the cross current is generated.

[0107] In Embodiment 2, the operation section 312 estimates the discharge upper limit current value of the parallel system as a whole at the time point of the convergence of the OCV after the unconnected battery pack 20 is connected to the parallel system. When the estimated discharge upper limit current value is equal to or higher than the threshold value based on the maximum value of the current required by the load, the determination section 313 permits the connection of the unconnected battery pack 20. When the estimated discharge upper limit current value is lower than the threshold value based on the maximum value of the current required by the load, the determination section 313 does not permit the connection of the unconnected battery pack 20. In addition, when the estimated discharge upper limit current value is equal to or higher than the discharge upper limit current value of the parallel system as a whole before the unconnected battery pack 20 is connected, the determination section 313 permits the connection of the unconnected battery pack 20. When the estimated discharge upper limit current value is lower than the discharge upper limit current value of the parallel system as a whole before the unconnected battery pack 20 is connected, the determination section 313 does not permit the connection of the unconnected battery pack 20.

[0108] Figure 10 is a graph for illustrating an example of the change in the discharge upper limit power value of the parallel system as a whole before and after the unconnected battery pack 20 is connected during discharging. For example, consider a state where the first battery pack 20a is connected to the load and the second battery pack 20b is not connected to the load as in the left side of Figure 9 . Hereinafter, the description is made on the premise that the same conditions are used in that a battery pack using the same kind of cells and the conditions related to the battery pack capacity, SOH, and temperature are the same. The SOC of the first battery pack 20a is set to 15%, and the SOC of the second battery pack 20b is set to 5%. If the SOC-discharge upper limit power characteristic shown in Figure 10 is referred to, the discharge upper limit power value when the SOC is 15% is 5.8 kW. The discharge upper limit power value of the parallel system as a whole in the state where only the first battery pack 20a is connected is also 5.8 kW.

[0109] Next, consider a state where the first battery pack 20a and the second battery pack 20b are connected to the load as in the right side of Figure 9the state of the right side of FIG. 6. When the second battery group 20b is connected to the parallel system, cross current occurs from the first battery group 20a to the second battery group 20b. Due to the cross current, the SOC of the first battery group 20a decreases and the SOC of the second battery group 20b increases. When the SOCs of both reach 10%, the cross current stops. Referring to the SOC-discharge upper limit power characteristic shown in FIG. 6, the discharge upper limit power value at the SOC of 10% is 2.0 kW. Thus, the discharge upper limit power value of the parallel system as a whole in the state where the first battery group 20a and the second battery group 20b are connected is 4.0 kW (= 2.0 kW x 2). Figure 10

[0110] In this example, when the second battery group 20b is connected, the discharge upper limit power value of the parallel system as a whole decreases from 5.8 kW to 4.0 kW. As shown in FIG. 6, in the state where the SOCs are uniform (SOC = 10%), the discharge upper limit power value is on the lower side of a virtual line that connects the discharge upper limit power value of the first battery group 20a (5.8 kW) before the second battery group 20b is connected and the discharge upper limit power value of the second battery group 20b (1.0 kW) with a straight line. When the second battery group 20b is connected, the discharge upper limit power value of the parallel system as a whole becomes lower than the power value obtained by simply averaging the discharge upper limit power value of the first battery group 20a (5.8 kW) before the second battery group 20b is connected and the discharge upper limit power value of the second battery group 20b (1.0 kW). Figure 10

[0111] Figure 11 is a flowchart for explaining the parallel connection determination process involved in Embodiment 2. When the power supply of the electric vehicle 1 is turned on ("Yes" in S20), the determination part 313 causes the relay drive part 25 to turn on the battery group relay RY1 that connects the battery group 20 having the highest OCV among the plurality of battery groups 20 (S21). When there are a plurality of battery groups 20 having the highest OCV, the determination part 313 causes a plurality of battery group relays RY1 that connect the plurality of battery groups 20 to be turned on at the same time.

[0112] During the execution of the parallel connection control ("No" in S22), when there is a battery group 20 for which the battery group relay RY1 is in the off state, the following process is executed. The determination part 313 determines the battery group 20 having the highest OCV among the battery groups 20 for which the battery group relay RY1 is in the off state as a connection candidate for which the battery group relay RY1 should be turned on next (S23).

[0113] ​​The operation section 312 estimates the convergence value of the OCV of the plurality of battery groups 20 connected to the parallel system in the case where the battery group 20 that is the connection candidate is connected (S24). The operation section 312 refers to the SOC-discharge upper limit current map 321 on the basis of the SOC corresponding to the converged OCV to derive the discharge upper limit current value of one battery group 20. The operation section 312 multiplies the discharge upper limit current value of one battery group 20 by the parallel number to estimate the discharge upper limit current value of the parallel system as a whole (S25). Furthermore, in deriving the SOC and the discharge upper limit current value of the battery group 20, the operation section 312 considers at least the temperature and the SOH of the battery group 20 as parameters.

[0114] The determination section 313 compares the estimated discharge upper limit current value of the parallel system as a whole with a threshold value based on the maximum value of the current required by the load (S27). In the case where the estimated discharge upper limit current value is equal to or higher than the threshold value (YES in S27), the determination section 313 permits the connection of the battery group 20 that is the connection candidate (S28), and causes the relay drive section 25 to turn on the battery group relay RY1 connected to the battery group 20 that is the connection candidate. In the case where the estimated discharge upper limit current value is lower than the threshold value (NO in S27), the determination section 313 does not permit the connection of the battery group 20 that is the connection candidate (S29). The processing proceeds to step S22.

[0115] Figure 12 is a flowchart for explaining the determination processing of the parallel connection involved in the modified example of Embodiment 2. Figure 12 The flowchart involved in the modified example of Embodiment 2 shown in Figure 11 The flowchart shown in FIG. 26 is obtained by adding the processing of step S26 to the flowchart involved in the basic example of Embodiment 2.

[0116] In step S26, the determination section 313 determines whether the estimated discharge upper limit current value of the parallel system as a whole will decrease due to the connection of the battery group 20 that is the connection candidate (S26). In the case where the discharge upper limit current value of the parallel system as a whole will not decrease (NO in S26), the determination section 313 permits the connection of the battery group 20 that is the connection candidate (S28), and causes the relay drive section 25 to turn on the battery group relay RY1 connected to the battery group 20 that is the connection candidate. In the case where the discharge upper limit current value of the parallel system as a whole will decrease (YES in S26), the processing proceeds to step S27.

[0117] In a modification, in the case where the discharge upper limit electric power value of the parallel system as a whole after connecting the unconnected battery group 20 is not lowered as a basic judgment criterion, even in the case where the discharge upper limit electric power value is lowered, if there is no problem in actual use, connection of the unconnected battery group 20 is allowed, whereby the waiting time of the battery group 20 can be reduced.

[0118] As explained above, according to Embodiments 1, 2, when the discharge upper limit current value or the discharge upper limit electric power value of the parallel system as a whole is lower than the threshold value based on the maximum value of the current or electric power required by the load due to connection of the unconnected battery group 20, connection of the unconnected battery group 20 is prohibited. Thereby, it is possible to prevent the current supplied from the parallel system to the load from becoming in an insufficient state, and thus it is possible to prevent generation of adverse effects such as reduction in acceleration performance of the electric vehicle 1.

[0119] Figure 13 is a view for explaining cross current between the battery groups 20 during charging. In Figure 13 In the left side state of FIG. 8, the first battery group relay RY1 connected to the first battery group 20a is turned on, and the second battery group relay RY1 connected to the second battery group 20b is turned off, and thus the state is a state where only the first battery group 20a is supplied with current from the power source (for example, the charger 2). In this case, the charge upper limit current value of the parallel system as a whole coincides with the charge upper limit current value of the first battery group 20a.

[0120] Figure 13 The right side state of FIG. 8 is a view showing a state after the second battery group relay RY1 is turned on. In the case where the OCV of the second battery group 20b is higher than the CCV in the case where the first battery group 20a is charged at the charge upper limit current value, cross current occurs from the second battery group 20b to the first battery group 20a. Thereby, although the charge upper limit current value of the first battery group 20a does not change, the current with which the first battery group 20a is charged from the power source decreases, and the charge upper limit current value of the parallel system as a whole from the power source decreases. In the case where the charger 2 charges at the maximum current, it is possible that charging is stopped due to control in the charger 2.

[0121] The CCV in the case where the first battery group 20a is charged at the charge upper limit current value is an estimated value. The current with which the first battery group 20a is charged varies depending on variation in the power source voltage and the like, and the CCV of the first battery group 20a varies depending on variation in the charging current. The CCV in the case where the first battery group 20a is charged at the charge upper limit current value is a value indicating the highest voltage at the time of charging of the first battery group 20a.

[0122] Next, consider a case where the second battery pack relay RYl is turned on in a case where the CCV in the case of charging the first battery pack 20a at the upper limit current value for charging coincides with the OCV of the second battery pack 20b. In a case where the current actually charging the first battery pack 20a from the power source coincides with the upper limit current value for charging of the first battery pack 20a, the CCV of the first battery pack 20a is equal to the OCV of the second battery pack 20b. In this case, no cross current occurs between the first battery pack 20a and the second battery pack 20b, and the upper limit current value for charging as a whole of the system does not decrease.

[0123] In a case where the current actually charging the first battery pack 20a from the power source is lower than the upper limit current value for charging of the first battery pack 20a, the actual CCV of the first battery pack 20a becomes lower than the CCV in the case of charging at the upper limit current value for charging. In this case, a cross current occurs from the second battery pack 20b to the first battery pack 20a. However, since the cross current stops in a case where the output current from the power source rises to the upper limit current value for charging of the first battery pack 20a, the upper limit current value for charging as a whole of the system does not decrease.

[0124] Next, consider a case where the second battery pack relay RYl is turned on in a case where the OCV of the second battery pack 20b is lower than the CCV in the case of charging the first battery pack 20a at the upper limit current value for charging. Since the upper limit current value for charging of the second battery pack 20b is greater than the upper limit current value for charging of the first battery pack 20a, the upper limit current value for charging as a whole of the system does not decrease when the second battery pack relay RYl is turned on.

[0125] Further, in the above description, an example in which both the upper limit current value for charging of each battery pack 20 and the upper limit current value for charging as a whole of the system are calculated by the arithmetic unit 312 of the management unit 30 is described. In this regard, the upper limit current value for charging of each battery pack 20 can also be calculated by the control unit 24 within the battery pack 20. The control unit 24 within each battery pack 20 transmits the calculated upper limit current value for charging of the battery pack 20 to the management unit 30. The arithmetic unit 312 of the management unit 30 calculates the upper limit current value for charging as a whole of the system based on the upper limit current value for charging of each received from the plurality of battery packs 20.

[0126] Next, two embodiments of the determination process for determining whether to allow parallel connection of the subject battery pack relay RYl during charging will be described. Embodiment 3 is a dynamic determination process, and Embodiment 4 is a static determination process.

[0127] Figure 14is a flowchart for explaining the determination process for the parallel connection involved in Embodiment 3. When the power supply of the electric vehicle 1 is turned on (equivalent to the ignition on of an engine vehicle) (YES in S30), the determination section 313 causes the relay drive section 25 to turn on the battery group relay RY1 connected to the battery group 20 having the lowest OCV among the plurality of battery groups 20 (S31). In the case where there are a plurality of battery groups 20 having the lowest OCV, the determination section 313 causes a plurality of battery group relays RY1 connected to the plurality of battery groups 20 to be turned on simultaneously.

[0128] During the execution of the parallel connection control (NO in S32), the following process is executed. The determination section 313 determines the battery group 20 having the lowest OCV among the battery groups 20 having the battery group relays RY1 in the off state as a connection candidate to which the battery group relay RY1 should be turned on next (S33).

[0129] The operation section 312 refers to the SOC-charging upper limit current map 322 based on the SOC of the battery group 20 having the battery group relay RY1 in the on state to derive the charging upper limit current value of the battery group 20. The operation section 312 applies the OCV, the internal resistance, and the charging upper limit current value of the battery group 20 to the above (Equation 2) to estimate the CCV corresponding to the charging upper limit current value of the battery group 20 (S34). Further, in deriving the SOC, the internal resistance, and the charging upper limit current value of the battery group 20, the operation section 312 considers at least the temperature and the SOH of the battery group 20 as parameters.

[0130] The operation section 312 estimates the current value flowing to the battery group 20 as the connection candidate in the case where the CCV of the battery group 20 as the connection candidate corresponds (is substantially equal to) to the CCV in the case where the battery group 20 already connected is charged at the charging upper limit current value (S36).

[0131] The current value flowing from the power supply uses a current value at the present time. Normally, the current value actually flowing from the power supply is lower than the charging upper limit current value, and therefore, the CCV of the battery group 20 already connected is lower than the CCV in the case where the battery group 20 already connected is charged at the charging upper limit current value by an amount corresponding to a voltage corresponding to the difference between the current values. The operation section 312 calculates a difference voltage between the actual CCV of the battery group 20 already connected and the CCV (= the CCV in the case where the battery group 20 already connected is charged at the charging upper limit current value) of the battery group 20 as the connection candidate, and estimates the current value flowing to the battery group 20 as the connection candidate based on the difference voltage and the internal resistance of the battery group 20 as the connection candidate. The current value is a cross current value flowing from the battery group 20 as the connection candidate to the battery group 20 already connected.

[0132] The operation section 312 estimates the charge upper limit current value of the parallel system as a whole after the connection of the battery group 20 that is the connection candidate, by subtracting the estimated current value (cross current value) from the charge upper limit current value of the parallel system as a whole before the connection of the battery group 20 that is the connection candidate (S37).

[0133] The determination section 313 compares the estimated charge upper limit current value after the connection with a threshold value based on the maximum value of the current that the power supply is able to output (S38). In the case where the charge upper limit current value after the connection is equal to or higher than the threshold value (YES in S38), the determination section 313 permits the connection of the battery group 20 that is the connection candidate (S39), and causes the relay drive section 25 to turn on the battery group relay RY1 that is connected to the battery group 20 that is the connection candidate. The processing proceeds to step S32. In the case where the charge upper limit current value after the connection is lower than the threshold value (NO in S38), the determination section 313 does not permit the connection of the battery group 20 that is the connection candidate (S310). The processing proceeds to step S32.

[0134] Further, in the case where there are a plurality of battery groups 20 in the on state, the CCVs corresponding to the charge upper limit current values of the plurality of battery groups 20 are identical. In this state where the CCVs are identical, the operation section 312 estimates the CCVs corresponding to the charge upper limit current values of the plurality of battery groups 20 that are in the on state.

[0135] Figure 15 is a flowchart for explaining the determination processing of the parallel connection involved in the application example of Embodiment 3. Figure 15 The flowchart involved in the application example of Embodiment 3 shown in Figure 14 The flowchart involved in the basic example of Embodiment 3 shown in

[0136] In step S35, the determination section 313 compares the estimated CCV in the case where the battery group 20 that has been connected is charged at the charge upper limit current value with the OCV of the battery group 20 that is the connection candidate (S35). In the case where the estimated CCV is equal to or higher than the OCV of the battery group 20 that is the connection candidate (YES in S35), the determination section 313 permits the connection of the battery group 20 that is the connection candidate (S39), and causes the relay drive section 25 to turn on the battery group relay RY1 that is connected to the battery group 20 that is the connection candidate. The processing proceeds to step S32. In the case where the estimated CCV in step S35 is lower than the OCV of the battery group 20 that is the connection candidate (NO in S35), the processing proceeds to step S36.

[0137] In the application example, in a case where the connected battery group 20 is being charged at the upper limit charging current value, if the estimated CCV is equal to or higher than the OCV of the battery group 20 that is a connection candidate, the operation processing of steps S36-S38 can be skipped, and thus the amount of calculation can be reduced.

[0138] Next, Embodiment 4 of the determination processing of parallel connection during charging will be described. As described above, in a case where the OCVs among the plurality of battery groups 20 that are connected in parallel are not uniform, cross current occurs from the battery group 20 with a high OCV to the battery group 20 with a low OCV. Due to the cross current, the OCV of the battery group 20 with a high OCV decreases, and the OCV of the battery group 20 with a low OCV increases. When the voltage difference between the two disappears, the cross current stops. In the state where the cross current stops, the OCVs among the plurality of battery groups 20 that are connected in parallel become uniform.

[0139] Figure 16 is a graph for explaining the cross current among the battery groups 20 during charging and the convergence of the OCVs. In Figure 16 , in order to make the explanation easy to understand, the parallel connection of two battery groups 20 is shown. The state on the left is a state where the first battery group relay RY1 connected to the first battery group 20a is on, and the second battery group relay RY1 connected to the second battery group 20b is off, showing a state where the OCV of the first battery group 20a is lower than the OCV of the second battery group 20b.

[0140] Figure 16 The state on the right of shows a state after the second battery group relay RY1 is on. When the first battery group 20a and the second battery group 20b are connected, current flows from the second battery group 20b to the first battery group 20a, the OCV of the second battery group 20b decreases, and the OCV of the first battery group 20a increases. When the OCVs of the two become uniform after a while, the cross current from the second battery group 20b to the first battery group 20a stops.

[0141] Under ideal conditions where the battery group capacities and the like are uniform, the SOC of the first battery group 20a and the second battery group 20b in the state where the cross current stops becomes an average of the SOC of the first battery group 20a before the cross current occurred and the SOC of the second battery group 20b, and the OCV in the state where the cross current stops becomes an OCV corresponding to the average SOC. Further, in a case where three or more battery groups 20 with non-uniform OCVs are connected in parallel, under ideal conditions, the OCVs of the three or more battery groups 20 become uniform due to the cross current. In this case, the OCVs of the three or more battery groups 20 after the OCVs become uniform become an average of the OCVs of the three or more battery groups 20 before the cross current occurred.

[0142] In Embodiment 4, the arithmetic portion 312 estimates the charge upper limit current value of the parallel system as a whole at the time point of OCV convergence after the unconnected battery group 20 is connected to the parallel system. When the estimated charge upper limit current value is equal to or higher than a threshold value based on the maximum value of the current that the power supply is able to output, the determination portion 313 permits connection of the unconnected battery group 20. When the estimated charge upper limit current value is lower than the threshold value based on the maximum value of the current that the power supply is able to output, the determination portion 313 does not permit connection of the unconnected battery group 20. In addition, when the estimated charge upper limit current value is equal to or higher than the charge upper limit current value of the parallel system as a whole before the unconnected battery group 20 is connected, the determination portion 313 permits connection of the unconnected battery group 20. When the estimated charge upper limit current value is lower than the charge upper limit current value of the parallel system as a whole before the unconnected battery group 20 is connected, the determination portion 313 does not permit connection of the unconnected battery group 20.

[0143] Figure 17 is a graph for explaining a change example of the charge upper limit current value of the parallel system as a whole before and after connection of the unconnected battery group 20 during charging. For example, consider a state in which the first battery group 20a is connected to the power supply and the second battery group 20b is not connected to the power supply, as in the left side of Figure 16 The SOC of the first battery group 20a is set to 80%, and the SOC of the second battery group 20b is set to 90%. If reference is made to the SOC-charge upper limit current characteristic shown in Figure 17 , the charge upper limit current value when the SOC is 80% is 15 A. The charge upper limit current value of the parallel system as a whole in a state in which only the first battery group 20a is connected is also 15 A.

[0144] Next, consider a state after the second battery group 20b is connected to the parallel system, as in the right side of Figure 16 When the second battery group 20b is connected to the parallel system, cross current occurs from the second battery group 20b to the first battery group 20a. Due to the cross current, the SOC of the second battery group 20b decreases and the SOC of the first battery group 20a increases. When the SOCs of both reach 85%, the cross current stops. If reference is made to the SOC-charge upper limit current characteristic shown in Figure 17 , the charge upper limit current value when the SOC is 85% is 6 A. Thus, the charge upper limit current value of the parallel system as a whole in a state in which the first battery group 20a and the second battery group 20b are connected is 12 A (= 6 A x 2).

[0145] In this example, when the second battery group 20b is connected, the charge upper limit current value of the parallel system as a whole decreases from 15 A to 12 A. AsFigure 16 As shown, the charging upper limit current value at the state where the SOC is uniform (SOC = 85%) is on the lower side of a virtual line connecting the charging upper limit current value (15 A) of the first battery group 20a before connection with the charging upper limit current value (2 A) of the second battery group 20b with a straight line, and the charging upper limit current value of the parallel system as a whole becomes lower than a current value obtained by simply averaging the charging upper limit current value (15 A) of the first battery group 20a before connection and the charging upper limit current value (2 A) of the second battery group 20b. Thus, when the charging upper limit current value of the parallel system as a whole after connection of the second battery group 20b is estimated without reference to the SOC-charging upper limit current characteristic, a state where the charging upper limit current value is estimated to be excessively large and the actual charging upper limit current value is lower than the charging current value from the charger 2 can occur.

[0146] Figure 18 is a flowchart for explaining the determination processing of the parallel connection involved in Embodiment 4. When the power supply of the electric vehicle 1 is turned on (YES in S40), the determination part 313 causes the relay drive part 25 to turn on the battery group relay RY1 that connects the battery group 20 having the lowest OCV among the plurality of battery groups 20 (S41). In the case where there are a plurality of battery groups 20 having the lowest OCV, the determination part 313 causes a plurality of battery group relays RY1 that connect the plurality of battery groups 20 to be turned on simultaneously.

[0147] During execution of the parallel connection control (NO in S42), in the case where there is a battery group 20 in which the battery group relay RY1 is in the off state, the following processing is executed. The determination part 313 determines the battery group 20 having the lowest OCV among the battery groups 20 in which the battery group relay RY1 is in the off state as a connection candidate in which the battery group relay RY1 should be turned on next (S43).

[0148] The calculation part 312 estimates the converged value of the OCVs of the plurality of battery groups 20 connected to the parallel system in the case where the battery group 20 that is the connection candidate is turned on (S44). The calculation part 312 refers to the SOC-charging upper limit current map 322 on the basis of the SOC corresponding to the converged OCV to derive the charging upper limit current value of one battery group 20. The calculation part 312 multiplies the charging upper limit current value of one battery group 20 by the number of parallel connections to estimate the charging upper limit current value of the parallel system as a whole (S45). Furthermore, in deriving the SOC and the charging upper limit current value of the battery group 20, the calculation part 312 considers at least the temperature and the SOH of the battery group 20 as parameters.

[0149] The determination section 313 compares the estimated charging upper limit current value of the parallel system as a whole with a threshold based on the maximum value of the current that the power supply is able to output (S47). In the case where the estimated charging upper limit current value is equal to or higher than the threshold ("Yes" in S47), the determination section 313 permits connection of the battery pack 20 that is a connection candidate (S48), and causes the relay drive section 25 to turn on the battery pack relay RY1 that is connected to the battery pack 20 that is a connection candidate. In the case where the estimated charging upper limit current value is lower than the threshold ("No" in S47), the determination section 313 does not permit connection of the battery pack 20 that is a connection candidate (S49). The processing proceeds to step S42.

[0150] Figure 19 Fig. 9 is a flowchart for explaining the determination processing of the parallel connection involved in the modified example of Embodiment 4. Figure 19 The flowchart involved in the modified example of Embodiment 4 shown in Fig. 9 is a flowchart obtained by adding the processing of step S46 to the flowchart involved in the basic example of Embodiment 4 shown in Fig. 8. Figure 18 The flowchart involved in the modified example of Embodiment 4 shown in Fig. 9 is a flowchart obtained by adding the processing of step S46 to the flowchart involved in the basic example of Embodiment 4 shown in Fig. 8.

[0151] In step S46, the determination section 313 determines whether the estimated charging upper limit current value of the parallel system as a whole will decrease due to connection of the battery pack 20 that is a connection candidate (S46). In the case where the charging upper limit current value of the parallel system as a whole will not decrease ("No" in S46), the determination section 313 permits connection of the battery pack 20 that is a connection candidate (S48), and causes the relay drive section 25 to turn on the battery pack relay RY1 that is connected to the battery pack 20 that is a connection candidate. In the case where the charging upper limit current value of the parallel system as a whole will decrease ("Yes" in S46), the processing proceeds to step S47.

[0152] In the modified example, in the case where the charging upper limit power value of the parallel system as a whole after connection of the unconnected battery pack 20 is the basic determination criterion, even in the case where the charging upper limit power value decreases, connection of the unconnected battery pack 20 is permitted in the case where there is no problem in actual use, and thus the waiting time of the battery pack 20 can be reduced.

[0153] As explained above, according to Embodiments 3 and 4, in the case where the charging upper limit current value or the charging upper limit power value of the parallel system as a whole decreases due to connection of the unconnected battery pack 20, the connection of the unconnected battery pack 20 is prohibited when the charging upper limit current value or the charging upper limit power value is lower than the threshold based on the maximum value of the current or the power that the power supply is able to output. Thus, it is possible to prevent an increase in charging time, waste of regenerative energy, and thus to prevent a decrease in charging efficiency of the battery pack 20.

[0154] The present disclosure has been described based on the embodiments. It should be understood by those skilled in the art that the embodiments are examples, and various modifications can be made to the respective elements and combinations of the processes, and such modifications are also within the scope of the present disclosure.

[0155] The determination process of parallel connection according to Embodiment 1 and the determination process of parallel connection according to Embodiment 2 can be combined. In this case, when connection is allowed in both determination processes, the battery group 20 is connected as a connection candidate, and when connection is not allowed in at least one determination process, the battery group 20 is not connected as a connection candidate. For example, there is also a case where, even when connection of the battery group 20 as a connection candidate is allowed in the determination process according to Embodiment 2, connection is not allowed in the determination process according to Embodiment 1.

[0156] The determination process according to Embodiment 2 determines whether the battery group 20 as a connection candidate can be connected based on the discharge upper limit value of the parallel system as a whole at a certain time point in the future. The discharge upper limit value during the process until the time point is not taken into account. On the other hand, the determination process according to Embodiment 1 determines whether the battery group 20 as a connection candidate can be connected based on the discharge upper limit value of the current time point that changes from time to time. Thus, there is also a case where the determination results of the two are not consistent. In the case where the determination process of parallel connection according to Embodiment 1 and the determination process of parallel connection according to Embodiment 2 are combined, the stability of the current supplied from the parallel system to the load can be further improved.

[0157] The determination process of parallel connection according to Embodiment 3 and the determination process of parallel connection according to Embodiment 4 can be combined. In this case, when connection is allowed in both determination processes, the battery group 20 is connected as a connection candidate, and when connection is not allowed in at least one determination process, the battery group 20 is not connected as a connection candidate. For example, there is also a case where, even when connection of the battery group 20 as a connection candidate is allowed in the determination process according to Embodiment 4, connection is not allowed in the determination process according to Embodiment 3.

[0158] The determination process in Example 4 determines whether a battery pack 20, a candidate for connection, can be connected based on the overall charging limit of the parallel system at a future point in time. It does not consider the charging limit during the process up to that point in time. On the other hand, the determination process in Example 3 determines whether a battery pack 20, a candidate for connection, can be connected based on the constantly changing charging limit at the current point in time. Therefore, inconsistencies may occur between the two determination processes. By using both the parallel connection determination process in Example 3 and the parallel connection determination process in Example 4, it is possible to further prevent a decrease in charging efficiency.

[0159] In the above embodiment, an example was described in which a management unit 30 is provided outside the plurality of battery packs 20. However, the management unit 30 may also be provided inside any one of the plurality of battery packs 20. In this case, the battery pack 20 that implements the function of the management unit 30 becomes the master unit, and the remaining battery packs 20 become slave units.

[0160] In the above embodiment, an example of connecting detachable, replaceable battery packs 20 in parallel was described. However, fixed battery packs 20 can also be connected in parallel. When using fixed battery packs 20, the functions of multiple control units 24 and management units 30, which are respectively provided in multiple battery packs 20, can be integrated. For example, the management unit 30 and the multiple control units 24 can be implemented by a single microcomputer.

[0161] In the above embodiments, an example of using a battery pack 20 that incorporates a battery module M1 including lithium-ion battery cells, nickel-metal hydride battery cells, lead-acid battery cells, etc., was described. In this regard, a capacitor pack that incorporates a capacitor module including double-layer capacitor cells, lithium-ion capacitor cells, etc., can also be used. In this specification, the battery module and capacitor module are collectively referred to as energy storage modules, and the battery pack and capacitor pack are collectively referred to as energy storage packs.

[0162] In the above embodiments, an example of connecting detachable and replaceable energy storage packs in parallel was described. In this respect, this disclosure can also be applied to the determination process for parallel connection of multiple energy storage modules within a single energy storage pack. Furthermore, in the above embodiments, an example of installing one energy storage module within a single energy storage pack is assumed; therefore, the determination process for parallel connection of multiple energy storage packs is equivalent to the determination process for parallel connection of multiple energy storage modules.

[0163] The mobile body powered by the replaceable battery pack 20 is not limited to the electric vehicle 1. For example, the mobile body also includes an electric ship. For example, the power source of a water bus, a water taxi can be configured as the replaceable battery pack 20. The battery pack 20 can also be a battery pack that supplies power to an outboard motor. In addition, the mobile body also includes an electric train. For example, an electric train equipped with the replaceable battery pack 20 can be used instead of an internal combustion engine vehicle used in a non-electrified line. The mobile body also includes an electrically powered flying body. The electrically powered flying body includes a multicopter (drone). The multicopter also includes a so-called flying car.

[0164] Furthermore, the embodiments can also be determined by the following items.

[0165] [Item 1]

[0166] A management device (30) for managing a plurality of power storage modules (M1) connected to a load (60), each power storage module (M1) being connected in parallel via a switch (RY1), characterized by

[0167] provided with a determination section (313) that, in a state in which the switches (RY1) connected to some of the plurality of power storage modules (M1) are turned on and the switches (RY1) connected to the remaining power storage modules (M1) among the plurality of power storage modules (M1) are turned off, when at least one of the switches (RY1) in the turned-off state is to be turned on, does not allow the turning on of the switch (RY1) when an upper limit value of a current or power allowed to be discharged from the plurality of power storage modules (M1) as a whole in a case where the switch (RY1) is turned on is lower than a first threshold value based on a maximum value of a current or power required by the load (60).

[0168] Accordingly, it is possible to prevent the current supplied from the plurality of power storage modules (M1) connected in parallel to the load (60) as a whole from becoming in an insufficient state due to the connection of the unconnected power storage module (M1).

[0169] [Item 2]

[0170] The management device (30) according to item 1, characterized by further being provided with:

[0171] an acquisition section (311) that acquires at least an SOC (State Of Charge) of each of the plurality of power storage modules (M1); and

[0172] The operation unit (312) estimates an upper limit value of the current or the electric power that is allowed to be supplied from the plurality of power storage modules (M1) as a whole, on the basis of an SOC-discharge upper limit characteristic that defines a relationship between the SOC of the power storage module (M1) and an upper limit value of the current or the electric power that is allowed to be discharged from the power storage module (M1),

[0173] The SOC-discharge upper limit characteristic is a characteristic in which the lower the SOC of the power storage module (M1), the lower the upper limit value of the current or the electric power that is allowed to be discharged from the power storage module (M1).

[0174] Accordingly, the upper limit value of the current or the electric power that is allowed to be supplied from the plurality of power storage modules (M1) as a whole to the load (60) can be determined with high precision.

[0175] [Item 3]

[0176] The management device (30) according to item 2, characterized in that

[0177] The acquisition unit (311) acquires an OCV (Open Circuit Voltage) of the power storage module (M1) that is a connection candidate among the remaining power storage modules (M1),

[0178] The operation unit (312) derives an upper limit value of the current or the electric power that is allowed to be discharged from the power storage module (M1) on the basis of the SOC-discharge upper limit characteristic and an SOC (State Of Charge) of the power storage module (M1) that is connected to the load (60), and estimates a CCV (Closed Circuit Voltage) of the power storage module (M1) in a case in which the power storage module (M1) is discharged at the upper limit value,

[0179] The determination unit (313) permits the opening of the switch that is connected to the power storage module (M1) that is the connection candidate, when the OCV of the power storage module (M1) that is the connection candidate is equal to or higher than the estimated CCV of the power storage module (M1),

[0180] When the OCV of the storage module (M1) that is the connection candidate is lower than the estimated CCV of the storage module (M1), the operation section (312) estimates the current value flowing to the storage module (M1) that is the connection candidate when the CCV of the storage module (M1) that is the connection candidate corresponds to the CCV of the storage module (M1) connected to the load (60) in the case where the discharge is performed up to the upper limit value, and sets a value obtained by subtracting the estimated current value from the upper limit value as the upper limit value of the current or the electric power that is allowed to be discharged from the plurality of storage modules (M1) as a whole, and when the upper limit value is equal to or higher than the first threshold value, the determination section (313) allows the opening of the switch.

[0181] Accordingly, it is possible to dynamically determine whether the current supplied from the plurality of storage modules (M1) as a whole to the load (60) will become in an insufficient state.

[0182] [Item 4]

[0183] The management device (30) according to any one of items 2 to 3, characterized in that,

[0184] The operation section (312) estimates the upper limit value of the current or the electric power that is allowed to be supplied from the plurality of storage modules (M1) as a whole when the OCV of the storage module (M1) connected to the load (60) corresponds to the OCV of the storage module (M1) that is the connection candidate after the opening of the switch (RY1) connected to the storage module (M1) that is the connection candidate, on the basis of the SOC-discharge upper limit characteristic, the SOC corresponding to the OCV of the storage module (M1) connected to the load (60), and the SOC corresponding to the OCV of the storage module (M1) that is the connection candidate,

[0185] When the estimated upper limit value is lower than the first threshold value or is lower than a second threshold value based on the upper limit value before the opening of the switch (RY1), the determination section (313) does not allow the opening of the switch (RY1).

[0186] Accordingly, it is possible to statically predict whether the current supplied from the plurality of storage modules (M1) as a whole to the load (60) will become in an insufficient state.

[0187] [Item 5]

[0188] The management device (30) according to any one of items 1 to 4, characterized in that,

[0189] When the supply of the electric power from the plurality of storage modules (M1) to the load (60) is started, the switch (RY1) connected to the storage module (M1) having the highest OCV among the plurality of storage modules (M1) is opened,

[0190] The OCV-highest storage module (Ml) in the storage modules (Ml) with the switch (RYl) in the off state becomes a connection candidate in which the switch (RYl) should be turned on next.

[0191] Accordingly, it is possible to connect the plurality of storage modules (Ml) in parallel while preventing the current supplied to the load (60) from becoming insufficient.

[0192] [Item 6]

[0193] A power supply system (10) characterized by comprising:

[0194] a plurality of storage modules (Ml) connected to a load (60), each storage module (Ml) being connected in parallel via a switch (RYl); and

[0195] The management device (30) according to any one of items 1 to 5.

[0196] Accordingly, it is possible to realize a power supply system (10) that can prevent the current supplied from the plurality of storage modules (Ml) connected in parallel as a whole to the load (60) from becoming insufficient due to the connection of an unconnected storage module (Ml).

[0197] [Item 7]

[0198] The power supply system (10) according to item 6, characterized in that,

[0199] the load (60) is a motor (60) of a mobile body (1),

[0200] the management device (30) notifies a control section (40) in the mobile body (1) of an upper limit value of the current or the power allowed to be supplied from the plurality of storage modules (Ml) as a whole to the motor (60).

[0201] Accordingly, it is possible to prevent adverse effects such as a decrease in acceleration performance of the mobile body (1).

[0202] [Item 8]

[0203] A management device (30) for managing a plurality of storage modules (Ml) connected to a power supply (60, 2), each storage module (Ml) being connected in parallel via a switch (RYl), the management device (30) characterized by comprising:

[0204] The determination unit (313) does not allow the opening of the switch (RY1) when the upper limit value of the current or the electric power that is allowed to charge the plurality of power storage modules (M1) as a whole when the switch (RY1) is opened is lower than a third threshold value based on the maximum value of the current or the electric power that can be output by the power supply (60, 2) when at least one of the switches (RY1) in the off state is to be turned on in a state where the switch (RY1) connected to a part of the plurality of power storage modules (M1) is turned on and the switch (RY1) connected to the remaining power storage modules (M1) among the plurality of power storage modules (M1) is turned off.

[0205] Accordingly, it is possible to prevent a decrease in charging efficiency of the plurality of power storage modules (M1) as a whole from the power supply (60, 2) due to connection of the unconnected power storage module (M1).

[0206] [Item 9]

[0207] The management device (30) according to Item 8, characterized by further comprising:

[0208] an acquisition unit (311) that acquires at least an SOC (State Of Charge) of each of the plurality of power storage modules (M1); and

[0209] an arithmetic unit (312) that estimates an upper limit value of the current or the electric power that is allowed to charge the plurality of power storage modules (M1) as a whole, based on an SOC-charge upper limit characteristic that defines a relationship between the SOC of the power storage module (M1) and the upper limit value of the current or the electric power that is allowed to charge the power storage module (M1),

[0210] The SOC-charge upper limit characteristic is a characteristic in which the higher the SOC of the power storage module (M1) is, the lower the upper limit value of the current or the electric power that is allowed to charge the power storage module (M1) is.

[0211] Accordingly, it is possible to determine the upper limit value of the current or the electric power that is allowed to charge the plurality of power storage modules (M1) with high precision.

[0212] [Item 10]

[0213] The management device (30) according to Item 9, characterized in that,

[0214] the acquisition unit (311) acquires an OCV (Open Circuit Voltage) of the power storage module (M1) that is a connection candidate among the remaining power storage modules (M1),

[0215] The operation section (312) derives an upper limit value of current or power that is allowed to charge the storage module (M1) based on the SOC-charge upper limit characteristic and an SOC (State Of Charge) of the storage module (M1) connected to the power supply (60, 2), and estimates a CCV (Closed Circuit Voltage) of the storage module (M1) in a case where the storage module (M1) is charged at the upper limit value,

[0216] When the OCV of the storage module (M1) as the connection candidate is lower than the estimated CCV of the storage module (M1), the determination section (313) allows the opening of the switch (RY1) connected to the storage module (M1) as the connection candidate,

[0217] When the OCV of the storage module (M1) as the connection candidate is higher than the estimated CCV of the storage module (M1), the operation section (312) estimates a current value that flows to the storage module (M1) as the connection candidate when the OCV of the storage module (M1) connected to the power supply (60, 2) corresponds to the CCV in a case where the storage module (M1) is charged at the upper limit value, and sets a value obtained by subtracting the estimated current value from the upper limit value as an upper limit value of current or power that is allowed to charge the plurality of storage modules (M1) as a whole, and when the upper limit value is equal to or higher than the third threshold value, the determination section (313) allows the opening of the switch.

[0218] According to this, it is possible to dynamically determine whether the charging efficiency of the plurality of storage modules (M1) as a whole from the power supply (60, 2) will decrease.

[0219] [Item 11]

[0220] The management device (30) according to Item 9 or 10, characterized in that,

[0221] The operation section (312) estimates an upper limit value of current or power that is allowed to charge the plurality of storage modules (M1) as a whole when the OCV of the storage module (M1) connected to the power supply (60, 2) corresponds to the OCV of the storage module (M1) as the connection candidate after the opening of the switch (RY1) connected to the storage module (M1) as the connection candidate, based on the SOC-charge upper limit characteristic, an SOC corresponding to the OCV of the storage module (M1) connected to the power supply (60, 2), and an SOC corresponding to the OCV of the storage module (M1) as the connection candidate,

[0222] When the estimated upper limit value is lower than the third threshold value or a fourth threshold value based on the upper limit value before the switch (RY1) is turned on, the determination unit (313) does not allow the switch (RY1) to be turned on.

[0223] Accordingly, it is possible to statically predict whether the charging efficiency from the power supply (60, 2) to the plurality of power storage modules (M1) as a whole will decrease.

[0224] [Item 12]

[0225] The management device (30) according to any one of items 8 to 11, characterized by

[0226] When the power supply from the power supply (60, 2) to the plurality of power storage modules (M1) is started, a switch (RY1) connected to a power storage module (M1) having the lowest OCV among the plurality of power storage modules (M1) is turned on,

[0227] The power storage module (M1) having the lowest OCV among the power storage modules (M1) in which the switch (RY1) is in the off state becomes a connection candidate in which the switch (RY1) should be turned on next.

[0228] Accordingly, it is possible to connect the plurality of power storage modules (M1) in parallel while preventing a decrease in the charging efficiency from the power supply (60, 2) to the plurality of power storage modules (M1) as a whole.

[0229] [Item 13]

[0230] A power supply system (10) characterized by comprising:

[0231] a plurality of power storage modules (M1) connected to a power supply (60, 2), each power storage module (M1) being connected in parallel via a switch (RY1); and

[0232] The management device (30) according to any one of items 8 to 12.

[0233] Accordingly, it is possible to realize a power supply system (10) that can prevent a decrease in the charging efficiency from the power supply (60, 2) to the plurality of power storage modules (M1) as a whole due to a connection of an unconnected power storage module (M1).

[0234] [Item 14]

[0235] The power supply system (10) according to item 13, characterized by

[0236] the power supply (60, 2) is a motor (60) of a mobile body (1) or an external charger (2),

[0237] The management device (30) notifies a control section (40) in the mobile body (1) of an upper limit value of current or power allowed to be regenerated from the motor (60) to the plurality of electric storage modules (M1) as a whole.

[0238] Accordingly, it is possible to prevent waste of regenerated energy generated by the motor (60).

[0239] Explanation of Reference Signs

[0240] 1: Electric vehicle; 2: Charger; 3: System; 5: Charging cable; 10: Power supply system; 20: Battery pack; 30: Management section; M1: Battery module; E1-En: Cell; 21: Voltage measurement section; 22: Temperature measurement section; 23: Current measurement section; 24: Control section; 241: SOC-OCV map; 25: Relay drive section; 31: Processing section; 311: Acquisition section; 312: Operation section; 313: Determination section; 314: Notification section; 32: Storage section; 321: SOC-discharge upper limit current map; 322: SOC-charge upper limit current map; 40: Vehicle ECU; 50: Inverter; 60: Motor; 70: AC / DC converter; RYc: Main relay; RY1: Battery pack relay; Rs: Shunt resistor; T1, T2: Temperature sensor.

Claims

1. A management device for managing a plurality of power storage modules connected to a load, each power storage module being connected in parallel via a switch, characterized by a determination section that, in a state in which a switch connected to a part of the plurality of power storage modules is turned on and a switch connected to the remaining power storage modules is turned off, does not allow turning on of at least one of the switches in the off state when an upper limit value of a current or power that is allowed to be discharged from the plurality of power storage modules as a whole in a case where the switch is turned on is lower than a first threshold value based on a maximum value of a current or power required by the load.

2. The management device according to claim 1, characterized by Further characterized by: an acquisition section that acquires at least a state of charge (SOC) of each of the plurality of power storage modules; and a calculation section that estimates an upper limit value of a current or power that is allowed to be discharged from the plurality of power storage modules as a whole, based on an SOC-discharge upper limit characteristic that defines a relationship between an SOC of the power storage module and an upper limit value of a current or power that is allowed to be discharged from the power storage module, the SOC-discharge upper limit characteristic is a characteristic in which the lower the SOC of the power storage module, the lower the upper limit value of the current or power that is allowed to be discharged from the power storage module.

3. The management device according to claim 2, characterized in that the acquisition section acquires an open circuit voltage (OCV) of the power storage module that is a connection candidate among the remaining power storage modules, the calculation section derives an upper limit value of a current or power that is allowed to be discharged from the power storage module connected to the load, based on the SOC-discharge upper limit characteristic and the SOC of the power storage module, and estimates a closed circuit voltage (CCV) of the power storage module in a case where the power storage module is discharged at the upper limit value, the determination section allows turning on of the switch connected to the power storage module that is the connection candidate when the OCV of the power storage module that is the connection candidate is equal to or higher than the estimated CCV of the power storage module, the calculation section estimates a current value that flows to the power storage module that is the connection candidate when the CCV of the power storage module that is the connection candidate corresponds to the CCV of the power storage module connected to the load in a case where the power storage module is discharged at the upper limit value, and sets a value obtained by subtracting the estimated current value from the upper limit value as the upper limit value of the current or power that is allowed to be discharged from the plurality of power storage modules as a whole, and the determination section allows turning on of the switch when the upper limit value is equal to or higher than the first threshold value.

4. The management device according to claim 2 or 3, characterized in that The operation section estimates an upper limit value of current or power that is allowed to be discharged from the plurality of power storage modules as a whole when the OCV of the power storage module connected to the load corresponds to the OCV of the power storage module as the connection candidate after the switch connected to the power storage module as the connection candidate is turned on, based on the SOC-discharge upper limit characteristic, the SOC corresponding to the OCV of the power storage module connected to the load, and the SOC corresponding to the OCV of the power storage module as the connection candidate, The determination section does not allow the switch to be turned on when the estimated upper limit value is lower than the first threshold value or is lower than a second threshold value based on the upper limit value before the switch is turned on.

5. The management device according to any one of claims 1 to 4, characterized in that a switch connected to the power storage module having the highest OCV among the plurality of power storage modules is turned on when the supply of power from the plurality of power storage modules to the load is started, the power storage module having the highest OCV among the power storage modules whose switches are in the off state becomes a connection candidate to which a switch should be turned on next.

6. A power supply system characterized by comprising: provided with a plurality of power storage modules connected to a load, each power storage module being connected in parallel via a switch; and the management device according to any one of claims 1 to 5.

7. The power supply system according to claim 6, characterized in that the load is a motor of a mobile body, the management device notifies a control section in the mobile body of an upper limit value of current or power that is allowed to be supplied from the plurality of power storage modules as a whole to the motor.

8. A management device for managing a plurality of power storage modules connected to a power supply, each power storage module being connected in parallel via a switch, the management device being characterized by provided with a determination section that, in a state in which a switch connected to a part of the plurality of power storage modules is turned on and a switch connected to the remaining power storage modules is turned off, does not allow at least one of the switches in the off state to be turned on when the upper limit value of current or power that is allowed to be charged to the plurality of power storage modules as a whole in the case where the switch is turned on is lower than a third threshold value based on a maximum value of current or power that can be output by the power supply.

9. The management device according to claim 8, characterized by Further provided with an acquisition section that acquires at least a state of charge (SOC) of each of the plurality of power storage modules; and an operation section that estimates an upper limit value of current or power that is allowed to be charged to the plurality of power storage modules as a whole based on an SOC-charge upper limit characteristic that defines a relationship between the SOC of the power storage module and the upper limit value of current or power that is allowed to be charged to the power storage module, the SOC-charge upper limit characteristic is a characteristic in which the higher the SOC of the power storage module is, the lower the upper limit value of current or power that is allowed to be charged to the power storage module is.

10. The management device according to claim 9, characterized in that the acquisition section acquires an open circuit voltage (OCV) of the power storage module as the connection candidate among the remaining power storage modules, the OCV of the power storage module as the connection candidate is higher than the OCV of the power storage module connected to the load. The operation section derives an upper limit value of current or power that is allowed to charge the storage module based on the SOC-charge upper limit characteristic and the SOC of the storage module connected to the power supply, and estimates a CCV of the storage module in a case where the storage module is charged at the upper limit value, The determination section allows the opening of the switch connected to the storage module as the connection candidate when the OCV of the storage module as the connection candidate is equal to or lower than the estimated CCV of the storage module, The operation section estimates a current value flowing to the storage module as the connection candidate when the OCV of the storage module as the connection candidate corresponds to the CCV of the storage module connected to the power supply in a case where the storage module is charged at the upper limit value when the OCV of the storage module as the connection candidate is higher than the estimated CCV of the storage module, and sets a value obtained by subtracting the estimated current value from the upper limit value as an upper limit value of current or power that is allowed to charge the plurality of storage modules as a whole, and the determination section allows the opening of the switch when the upper limit value is equal to or higher than the third threshold value.

11. The management device according to claim 9 or 10, wherein The operation section estimates an upper limit value of current or power that is allowed to charge the plurality of storage modules as a whole when the OCV of the storage module connected to the power supply corresponds to the OCV of the storage module as the connection candidate after the opening of the switch connected to the storage module as the connection candidate based on the SOC-charge upper limit characteristic, the SOC corresponding to the OCV of the storage module connected to the power supply, and the SOC corresponding to the OCV of the storage module as the connection candidate, The determination section does not allow the opening of the switch when the estimated upper limit value is lower than the third threshold value or a fourth threshold value based on the upper limit value before the opening of the switch.

12. The management device according to any one of claims 8 to 11, wherein The switch connected to the storage module having the lowest OCV among the plurality of storage modules is opened when the supply of power from the power supply to the plurality of storage modules is started, The storage module having the lowest OCV among the storage modules whose switches are in the off state becomes a connection candidate to which a switch should be opened next.

13. A power supply system characterized by comprising: comprises: a plurality of storage modules connected to a power supply in parallel via switches, respectively; and The management device according to any one of claims 8 to 12.

14. The power supply system according to claim 13, wherein The power supply is a motor of a mobile body or an external charger, The management device notifies a control section in the mobile body of an upper limit value of current or power that is allowed to regenerate from the motor to the plurality of storage modules as a whole.

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