Battery management device and battery management system

Abstract

To simplify charging / discharge control over a plurality of batteries which is charged and discharged through an electric power supply network.SOLUTION: Battery management devices 14-i (i is an integer of 1 to N) which manage charging / discharging states of batteries 14-i comprise charging / discharging controllers 16-i and battery agents Ci. The batteries 14-i are connected to the charging / discharging controllers 16-i. The charging / discharging controllers 16-i control supply electric power supplied from the batteries 14-i to a load device 20 or supplied from an electric power source 26 to the batteries 14-i. A central control device 10 determines a supply electric power error for the load device 20 or electric power source 26. The battery agents Ci measure charging states of the batteries 14-i, and receive the supply electric power error from the central control device 10. The battery agents Ci determine an electric power target value based upon the charging states of the batteries 14-i and the supply electric power error. The charging / discharging controllers 16-i control the supply electric power based upon the electric power target value.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a battery management device and a battery management system, and more particularly to a technique for charging and discharging a battery. [Background technology]

[0002] Electric vehicles, such as hybrid vehicles and electric vehicles, which run on battery power, are widely used. For electric vehicles, charging devices connected to a power supply network provided by an electric power supplier or the like are installed at service stations, parking lots, etc. The batteries of the electric vehicles are charged by the charging devices.

[0003] Furthermore, battery-powered electric devices such as forklifts and transport vehicles are used in factories, offices, event venues, etc. To use multiple electric devices in various locations within the premises of a factory, office, etc., charging systems have been developed in which charging devices are connected to key points in a locally constructed power supply network.

[0004] A known technology related to such charging systems is one that controls multiple charging devices connected to a power supply network or load devices. In this technology, a control device acquires information indicating the state of charge of a battery from each charging device, and the control device controls each charging device according to the state of charge of the battery in each charging device. Patent Document 1 describes a distributed power supply system that uses this technology. This distributed power supply system includes multiple power conversion units (charging devices) and a control unit (control device) that controls each power conversion unit. A battery is connected to each power conversion unit. The control unit acquires the SOC (State of Charge) of the battery from each of the multiple power conversion units, and controls charging and discharging of each power conversion unit according to the SOC.

[0005] Non-Patent Document 1 also describes a battery power storage system, in which an average SOC value for the entire system is estimated for each battery depending on the difference in SOC between one battery and the other batteries, and charging and discharging of each battery is controlled based on the estimation result. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-116428 [Non-patent literature]

[0007] [Non-Patent Document 1] Zeraati, M., Golshan, MEH, & Guerrero, JM (2018). Distributed Control of Battery Energy Storage Systems for Voltage Regulation in Distribution Networks with High PV Penetration. IEEE Transactions on Smart Grid,9(4), 3582-3593. Summary of the Invention [Problem to be solved by the invention]

[0008] In charging systems using conventional technology, each charging device had to transmit information indicating the charging status of its own battery to a control device or another charging device, which could make controlling the charging and discharging of batteries connected to each charging device complicated.

[0009] An object of the present invention is to simplify the charge / discharge control of each of a plurality of batteries that are charged / discharged between the batteries and a load device. [Means for solving the problem]

[0010] The present invention is a method for detecting the charge and discharge state of a battery. Each one Manage Multiple management device In a battery management system including theA battery management device comprising: a charge / discharge controller connected to the battery and controlling power supplied from the battery to a load device or power supplied from a power source to the battery; and a battery agent; the battery management system includes a central control device that determines a supply power error for the load device or the power source for the plurality of battery management devices; The battery agent measures the state of charge of the battery and In the notes Central control unit Before The supply power error is received, and a power target value is calculated based on the state of charge and the supply power error. The charge / discharge controller controls the supply power based on the power target value. The central control device calculates a total supply power by adding up the power supplied from the plurality of battery management devices to the load device or the power supplied from the power source to the plurality of battery management devices, calculates the supply power error based on the difference between the total supply power and the power requested to be supplied from each of the battery management devices to the load device or the power requested to be supplied from the power source to each of the battery management devices, and transmits the supply power error to the battery agent included in each of the battery management devices. It is characterized by:

[0011] Preferably, the battery agent determines the power target value that varies based on a time rate of change according to the state of charge.

[0012] Preferably, the battery agent calculates a control gain according to the state of charge, calculates a control value that changes at a time rate according to the control gain, and applies limit processing to the control value to restrict the range of possible values, thereby calculating the power target value.

[0013] Preferably, the limit processing is a process that, when the control value is within a predetermined variable range, calculates the power target value so that it increases or decreases in response to an increase or decrease in the control value, and, when the control value is outside the variable range, calculates the power target value so that it is constant at an upper limit value or a lower limit value in response to changes in the control value.

[0014] Preferably, the battery agent measures a value indicating the amount of charge of the battery, and when the value indicating the amount of charge of the battery is outside a predetermined range, the charge / discharge controller stops charging or discharging the battery.

[0015] Preferably, the battery agent measures the degree of deterioration of the battery, and when the degree of deterioration exceeds a predetermined level, the charge / discharge controller stops charging or discharging the battery.

[0016] Preferably, the battery agent measures a value indicating the amount of charge stored in the battery, and when the value indicating the amount of charge stored in the battery matches a target value or the difference between the value indicating the amount of charge stored in the battery and the target value falls within a predetermined range, the charge / discharge controller stops charging or discharging the battery.

[0017] The present invention also provides a battery management system including a plurality of battery management devices, the system including the central control device. It is characterized by do. [Effects of the Invention]

[0018] According to the present invention, it is possible to simplify the charge / discharge control of a plurality of batteries that are charged / discharged between the batteries and a load device. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a diagram showing a battery system according to an embodiment of the present invention; [Figure 2] 10 is a flowchart of a process executed by a central control device and a battery agent. [Figure 3] FIG. 10 is a diagram showing a power target value yi relative to a control value φi. [Figure 4] FIG. 10 is a diagram showing the simulation results of the total power supply y measured by the central control device. [Figure 5] FIG. 10 is a diagram showing the simulation results of the supply power error e obtained by the central control device. [Figure 6] FIG. 10 is a diagram showing the power target value yi determined by each battery management device and the SOC of each battery. [Figure 7] FIG. 10 is a diagram illustrating control gains during charging and discharging. [Figure 8] FIG. 10 is a diagram showing target power values ​​during charging and discharging. [Figure 9] FIG. 2 is a diagram showing an equivalent circuit of a battery. DETAILED DESCRIPTION OF THE INVENTION

[0020] The embodiments of the present invention will be described with reference to the drawings. The same elements shown in multiple drawings will be designated by the same reference numerals to simplify the description.

[0021] FIG. 1 shows a battery management system 100 according to an embodiment of the present invention. The battery management system 100 includes a central control device 10, battery management devices 12-1 to 12-N, batteries 14-1 to 14-N, and a power transmission line 18. The batteries 14-1 to 14-N are connected to the battery management devices 12-1 to 12-N, respectively. The battery management devices 12-1 to 12-N are connected to the power transmission line 18. The power transmission line 18 is connected to a load device 20 and a power source 26 at a distance from the battery management devices 12-1 to 12-N. The power transmission line 18 may be a power transmission line that transmits AC power or a power transmission line that transmits DC power. The central control device 10 is connected to each of the battery management devices 12-1 to 12-N via a communication line 22. The central control device 10 is also connected to the load device 20 via a communication line 24, and the central control device 10 is also connected to the power source 26 via a communication line 28. These communication lines may be wireless communication lines, wired communication lines, or a combination of these.

[0022] The battery management device 12-i (i is an integer from 1 to N) includes a battery agent Ci and a charge / discharge controller 16-i, and manages the charge / discharge state of the battery 14-i. The battery agent Ci may be a processor that controls the charge / discharge controller 16-i by executing a program. The battery 14-i is connected to the charge / discharge controller 16-i, which is connected to a power transmission line 18. The charge / discharge controller 16-i may include a DC / AC converter circuit that performs direct current / alternating current conversion between the battery 14-i and the power transmission line 18. The charge / discharge controller 16-i may also include a DC / DC converter circuit that adjusts the magnitude relationship between the output voltage of the battery 14-i and the voltage of the power transmission line 18. The charge / discharge controller 16-i adjusts the supply power output from the battery 14-i to the power transmission line 18 under the control of the battery agent Ci. Here, when the supplied power is positive, it represents the power discharged from the battery 14-i to the power transmission line 18. When the supplied power is negative, the absolute value of the supplied power represents the power charged from the power transmission line 18 to the battery 14-i.

[0023] The power (total supply power) obtained by adding up the power supplied from each battery management unit 12-i to the load device 20 via the power transmission line 18 is supplied to the load device 20. In addition, the power supplied from the power source 26 to each battery management unit 12-i via the power transmission line 18 is supplied to each battery 14-i.

[0024] 2 shows a flowchart of the processing executed by the central control device 10 and the battery agent Ci provided in each battery management device 12-i. Steps S11 to S14 are processing executed by the central control device 10, and steps S21 and S22 are processing executed by the battery agent Ci.

[0025] The central control device 10 acquires the requested power from the load device 20 via the communication line 24 (S11). Alternatively, the central control device 10 acquires the requested power from the power source 26 via the communication line 28 (S11). Here, the requested power of the load device 20 is a target value of power to be supplied to the load device 20 from the power transmission line 18. The requested power of the power source 26 is a target value of power to be supplied from the power source 26 to the power transmission line 18. The central control device 10 measures the total supply power supplied from each battery management unit 12-i to the load device 20, or the total supply power supplied from the power source 26 to each battery management unit 12-i (S12). That is, the central control device 10 measures the total supply power supplied from each battery 14-i to the load device 20, or the total supply power supplied from the power source 26 to each battery 14-i (S12). The central control device 10 calculates a supply power error by subtracting the measured value of the total supply power from the requested power (S13). The central control device 10 generates control information for controlling each battery management device 12-i based on the supply power error and transmits the control information to the battery agent Ci of each battery management device 12-i via the communication line 22 (S14). The control information includes the supply power error and a charge / discharge command flag indicating whether each battery 14-i should be charged or discharged. The battery agent Ci controls the charge / discharge of the battery 14-i based on the control information.

[0026] The battery agent Ci measures the SOC (State Of Charge) as a physical quantity representing the state of charge of the battery 14-i (S21). The SOC represents the amount of charge relative to the charge capacity of the battery. The battery agent Ci determines the power target value y based on the control information transmitted from the central control device 10 and the SOC of the battery 14-i. i The power target value y is calculated (S22). i is a target value for the supply power supplied from the battery 14-i to the power transmission line 18, or the charging power supplied from the power transmission line 18 to the battery 14-i. iThe charge / discharge controller 16-i outputs the power supply value y to the charge / discharge controller 16-i (S23). The charge / discharge controller 16-i controls the supply power supplied from the battery 14-i to the power transmission line 18 or the charging power supplied from the power transmission line 18 to the battery 14-i to the power target value y i To approach or match.

[0027] The battery agent Ci sets the power target value y i The process of calculating the control value φ will be described below. The battery agent Ci calculates the control value φ according to (Equation 1) based on the supply power error e included in the control information. i (Equation 1) is K i The control value φ is calculated based on the proportional integral with the control gain i As will be described later, the battery agent Ci determines the control gain K i Ask for.

[0028]

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[0029] Here, φ with a dot on it i is the control value φ i In the following explanation, a variable with a dot above it indicates the time derivative of that variable. i is the control value φ i is a positive number that adjusts for time variations.

[0030] In the battery management system 100 according to this embodiment, the batteries 14-1 to 14-N are charged and discharged at a rate (change in SOC per unit time) according to their respective SOCs, so that the SOCs of the batteries 14-1 to 14-N are equalized over time. This control is performed by using a control gain K i Here, the battery agent Ci determines the control gain K i is determined, and the control value φ i Based on the power target value y i The process for obtaining this will be described.

[0031] When the charge / discharge command flag included in the control information indicates a discharge request, the battery agent Ci calculates the control gain K according to (Equation 2) based on the SOC measured in step S21 of FIG. i Ask for.

[0032]

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[0033] where K L and K. H is the control gain K for SOC i In (Equation 2), when the SOC is less than 10%, when the SOC is 10% or more and less than 20%, or when the SOC is 90% or more, the control value φ i is forced to 0. As a result, when the SOC of the battery 14-i is 20% or more and less than 90%, discharge control is performed on the battery 14-i, and when the SOC is less than 20% and 90% or more, discharge of the battery 14-i is stopped. Furthermore, (Equation 2) has a positive slope (K H -K L ) / 60 is the control gain K i The larger the SOC, the faster the discharge rate. i The range of change is K L That's all, K H is less than.

[0034] Control value φ i The battery agent Ci calculates the power target value y i Ask for.

[0035]

number

[0036] The power target value y i is 0 or a positive value. The power target value yi A positive value of φ means that the battery 14-i is discharged. ni and φ pi is the power target value y i is any positive number that defines the properties of Y. p is the power target value y i Here, the charge / discharge command flag indicates a discharge request, so Y p indicates the maximum discharge power. i Power target value y i The horizontal axis represents the control value φ i The vertical axis represents the power target value y i Shows.

[0037] When the charge / discharge command flag included in the control information indicates a charge request, the battery agent Ci calculates the control gain according to (Equation 4) based on the SOC measured in step S21 of FIG.

[0038]

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[0039] In (Equation 4), when the SOC is 10% or less, when the SOC is 80% or more but less than 90%, or when the SOC is 90% or more, the control value φ i is forced to 0. As a result, when the SOC of the battery 14-i is greater than 10% and less than or equal to 80%, charging control is performed on the battery 14-i, and when the SOC is less than or equal to 10% and greater than 80%, charging of the battery 14-i is stopped. Furthermore, (Equation 4) indicates that when the SOC is in the range of greater than 20% and less than or equal to 80%, a negative slope (K L -K H ) / 60 is the control gain K i The smaller the SOC, the faster the charging speed. i The range of change is K L That's all, K H The range is less than.

[0040] Control value φ i The battery agent Ci calculates the power target value y i Ask for.

[0041]

number

[0042] The power target value y i is 0 or a negative value. i A negative value of -Y means that the battery 14-i is being charged. p is the power target value y i Here, the charge / discharge command flag indicates a charge request, so Y p indicates the maximum charging power. i Power target value y i The horizontal axis represents the control value φ i The vertical axis represents the power target value y i Shows.

[0043] In this way, the battery agent Ci performs the processing according to (Equation 1) to (Equation 5) to obtain the power target value y i The battery agent Ci calculates the power target value y i The charge / discharge controller 16-i outputs the power target value y i When is a positive number, the power supplied from the battery 14-i to the power transmission line 18 is set to the power target value y i The charge / discharge controller 16-i makes the target power value y i When |y| is a negative number, the charging power supplied to the battery 14-i from the power transmission line 18 is set to the absolute value of the power target value |y| i The charge / discharge controller 16-i makes the target power value y i When the value is 0, charging and discharging of the battery 14-i is stopped.

[0044] As shown in (Equation 3) and (Equation 5), the control value φ i is within a predetermined variable range, the control value φ i The power target value y increases or decreases with an increase or decrease in i That is, the control value is -φ pi Exceeds -φ ni or, φ ni Above, φ pi If it is less than φ i The power target value y increases or decreases with an increase or decrease in i Also, the control value φ i When is out of the variable range, the control value φ i The power target value y that remains constant at the upper or lower limit with respect to the change in i is required.

[0045] In this way, the battery agent Ci controls the control value φ which changes at a time rate according to the SOC. i The limiting process to limit the range of possible values ​​is performed using the control value φ i By applying this to the power target value y i The limit process is performed by using the control value φ i is within a predetermined variable range, the control value φ i The power target value y increases or decreases with an increase or decrease in i and the control value φ i When is out of the variable range, the control value φ i The upper limit for the change in Y p Constant or lower limit - Y p The power target value y i The limiting process prevents excessive power from being supplied from the battery 14-i to the power transmission line 18 and prevents excessive charging power from being supplied to the battery 14-i.

[0046] As shown in (Equation 2) to (Equation 5), when the SOC of the battery 14-i is close to 0 or close to 100%, that is, when the control value φ i If is close to 0, the power target value y iis 0. Generally, when the charge amount of a battery is 0 or when the battery is fully charged, the power efficiency may be low. According to the control expressed by (Equation 1) to (Equation 5), the battery 14-i is charged and discharged within the SOC range in which the power efficiency of the battery 14-i is relatively high.

[0047] Each battery agent Ci executes control according to Equations 1 to 5, causing batteries 14-1 to 14-N to charge and discharge at a rate (change in SOC per unit time) according to their respective SOCs. This equalizes the SOCs of batteries 14-1 to 14-N over time, preventing a particular battery from being overloaded with electricity. For example, this prevents a charge / discharge controller connected to a particular battery from experiencing large losses, or a particular battery from having a shorter lifespan than other batteries.

[0048] Furthermore, for a battery 14-k (k is an integer between 1 and N) whose SOC is not within a predetermined range (in the above example, the range is between 20% and 90% when discharging, and the range is between 10% and 80% when charging), the power target value y k is forcibly set to 0. That is, when the value indicating the amount of charge stored in battery 14-k is outside a predetermined range, charge / discharge controller 16-k stops charging or discharging battery 14-k. Even when charge / discharge control of battery 14-k is stopped in this way, other battery management devices perform control according to (Equation 1) to (Equation 5), and the shortfall in total power supply is made up by other batteries.

[0049] The battery agent Ci may constitute a deterioration level meter that measures the deterioration level of the battery 14-i. The deterioration level may be a value that increases as the SOH (State Of Health) decreases. Here, the SOH is defined as the ratio of the current charge capacity (Ah) to the charge capacity (Ah) when the battery is new. In step S22 shown in FIG. 2, when the deterioration level of the battery 14-i exceeds a predetermined level, the power target value y imay be forced to 0. As a result, when the degree of deterioration of the battery 14-i exceeds a predetermined level, the charge / discharge controller 16-i stops charging or discharging the battery 14-i.

[0050] Furthermore, when the SOC of the battery 14-i reaches a predetermined target value, or when the difference between the SOC of the battery 14-i and the target value falls within a predetermined range, the battery agent Ci adjusts the power target value y i may be forcibly set to 0. In this case, the charge / discharge controller 16-i stops charging or discharging the battery 14-i when the SOC of the battery 14-i matches the target value or when the difference between the SOC of the battery 14-i and the target value falls within a predetermined range. This stops the charge / discharge control of the battery 14-i whose SOC has approached or matched the target value.

[0051] Even when the charge / discharge control of battery 14-i is stopped, the other battery management devices perform control according to (Equation 1) to (Equation 5), and the shortage of total power supply is made up by the other batteries.

[0052] In the battery management system 100 according to this embodiment, common control information is transmitted from the central control device 10 to each battery management device 12-i. Each battery management device 12-i performs autonomous and decentralized charge and discharge control of the battery 14-i in accordance with the common control information in the battery management system 100. This reduces the amount of information transmitted between the central control device 10 and each battery management device 12-i, and simplifies the charge and discharge control of the multiple batteries 14-1 to 14-N in the battery management system 100.

[0053] FIG. 4 shows the results of a simulation of the total supply power y measured by the central control device 10 in the battery management system 100. The horizontal axis indicates time, and the vertical axis indicates the total supply power y. As shown in the lower part of FIG. 4, a first state in which the total supply power y is positive and power is supplied from the power transmission line 18 to the load device 20, and a second state in which the total supply power y is negative and power is supplied from the power source 26 to the power transmission line 18 are repeated over time. The characteristics of the total supply power y shown on the left and right sides of the upper part of FIG. 4 are enlarged versions of the characteristics of the total supply power y shown in the lower part in the vertical and horizontal directions. The left side of the upper part of FIG. 4 shows the total supply power y when the battery management system 100 transitions from the second state to the first state, compared to the required power y r 4, the total supply power y when the battery management system 100 transitions from the first state to the second state is shown together with the required power y. r In this way, the total power supply y is shown on the left and right of the top row of Figure 4. r It has been shown that the temperature changes in accordance with the

[0054] FIG. 5 shows the supply power error e=y r 5 shows the simulation results for -y. The horizontal axis represents time, and the vertical axis represents the supply power error e. As shown in the lower part of FIG. 5, when the battery management system 100 transitions from the second state to the first state and from the first state to the second state, the supply power error e becomes a non-zero value. The characteristics of the supply power error e shown on the left and right sides of the upper part of FIG. 5 are enlarged versions of the characteristics of the supply power error e shown in the lower part along the vertical and horizontal axes. The upper left side of FIG. 5 shows the supply power error e when the battery management system 100 transitions from the second state to the first state. The upper right side of FIG. 5 shows the supply power error e when the battery management system 100 transitions from the first state to the second state. As shown, the upper left and right sides of FIG. 5 show that the supply power error e becomes a non-zero value when the battery management system 100 transitions between states, but quickly converges to zero.

[0055] The upper part of FIG. 6 shows the power target value y obtained by the battery management units 12-1 to 12-10 when N=10. i (i=1 to 10) is shown. The horizontal axis indicates time, and the vertical axis indicates the power target value y i The power target value y1 has the largest absolute value, and the power target value y 10 The absolute value of y1, y2, y9, y 10 The absolute values ​​are larger in this order. In the lower part of Fig. 6, SOCi (i = 1 to 10) is shown as the SOC of battery 14-i. The horizontal axis indicates time and the vertical axis indicates SOC. In the example shown in Fig. 6, the battery management system 100 repeats a first state and a second state over time. As shown in the lower part of Fig. 6, of SOC1 to SOC10, SOC1 has the largest value. The values ​​are then larger in this order: SOC2, SOC3, ..., SOC10, with SOC10 being the smallest.

[0056] y i In the first state where y is positive, power is supplied from each battery management unit 12-i to the load device 20 via the power transmission line 18. That is, power is discharged from each battery 14-i to the power transmission line 18. The higher the SOC of a battery 14-i, the faster the discharge rate and the greater the decrease in SOC per unit time. i In the second state where is negative, in principle, power is supplied from the power source 26 to each battery management unit 12-i via the power transmission line 18. That is, power is supplied to each battery 14-i from the power transmission line 18, and each battery 14-i is charged. The smaller the SOC of a battery 14-i, the faster it is charged, and the greater the increase in SOC per unit time.

[0057] However, in the example shown in FIG. 6, the SOC10 is equal to or lower than the lower limit in the time period Ts, and the power target value y 10 is 0. In the time period Ts, the time change of SOC10 is 0. Also, in the time period Ts, the power target value y 10The power target values ​​y1 to y9 of the other batteries 14-1 to 14-9 have increased by the amount that the power target value y1 to y9 of the other batteries 14-1 to 14-9 has become 0. That is, the shortage in the total power supply caused by the battery 14-10 stopping discharging is made up for by the discharged power of the batteries 14-1 to 14-10.

[0058] In the first state, the discharge control of each battery 14-i is performed so that the battery 14-i with a higher SOC is discharged at a faster rate, and in the second state, the charge control of each battery 14-i is performed so that the battery 14-i with a lower SOC is charged at a faster rate. This causes the SOCs of the batteries 14-1 to 14-10 to converge to the same value over time, thereby preventing a particular battery from being subjected to a large electrical load.

[0059] The principle of equalizing the SOC of N batteries by controlling each battery management unit 12-i will be described in detail. i , the charge capacity of battery 14-i is cap i , the current flowing out of the battery 14-i is i i Then, x i is expressed as (Equation 6).

[0060]

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[0061] where x i (0) is the SOC of the battery 14-i at time t = 0. By differentiating both sides of (Equation 6) with respect to time, (Equation 7) is obtained.

[0062]

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[0063] Supply power error e, control gain K i and the control value φ i There is a relationship expressed by (Equation 8).

[0064]

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[0065] Control gain K i (x i ) is the control gain K obtained according to (Equation 2) and (Equation 4). i Regarding SOC x i In Fig. 7(a), the control gain K i (x i ) is shown. The horizontal axis is x i The vertical axis indicates the control gain K i (x i ) Control gain K i (x i ) is x min That's all, x max In the range less than x i The slope β i In (Equation 2), x min is 20%, and x max is 80%. β i (K H -K L ) / (x max -x min )

[0066] Figure 7(b) shows the control gain K i (x i ) is shown. The horizontal axis is x i The vertical axis indicates K i (x i ) Control gain K i (x i ) intercept is β i0 and the control gain K i (x i ) is x min Exceeds x max In the following range, x i The slope of -β i In (Equation 4), x min is 20%, and x max is 80%. -β i (K L -K H ) / (xmax -x min )

[0067] Control value φ i and the power target value y i There is a relationship expressed by (Equation 9).

[0068]

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[0069] Figure 8(a) shows the power target value σ i (φ i ) is shown, and Fig. 8(b) shows the power target value σ i (φ i ) are shown. The power target values ​​σ i (φ i ) are respectively shown in Fig. 3(a) and (b) as φ ni = 0. That is, φ in Fig. 3(a) and (b) ni is approximated to 0 as being sufficiently small. i ) control value φ i The slope g i is Y p / φ pi is.

[0070] x i If we assume that the time change of is sufficiently small, and time-integrate (Equation 8), we get φ i and control gain K i (x i ) we obtain the following equation (10).

[0071]

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[0072] Here, E is the time integral value of the supply power error e, and is expressed by (Equation 11).

[0073]

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[0074] Based on the relationships shown in (Equation 7) to (Equation 11) and FIGS. 7 and 8, the power target value y i is expressed as (Equation 12).

[0075]

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[0076] where σ i (φ i ) slope g i is defined as (Equation 13) using an arbitrary constant α common to the batteries 14-1 to 14-N belonging to the battery management system 100.

[0077]

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[0078] By this definition, the power target value y i is expressed as in (Equation 14).

[0079]

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[0080] Figure 9 shows an equivalent circuit of the battery 14-i. The battery 14-i is represented by a circuit in which a DC constant voltage source 30 and an internal resistor 32 are connected in series. The output voltage of the DC constant voltage source 30 (open circuit voltage of the battery 14-i) is expressed as v oi The resistance value of the internal resistor 32 is R i In this case, the output voltage of battery 14-i is v i and discharge power z i are expressed as (Equation 15) and (Equation 16), respectively.

[0081]

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[0082] In the following explanation, the discharge power z i is the power target value y i The internal resistance R of the battery 14-i is assumed to be equal to i If is sufficiently small, the current i flowing out of the battery 14-i i is z i / v oi =y i / v oi Therefore, the SOC during charging and discharging, that is, x during charging and discharging, i is i i =y i / v oi Substituting into (Equation 7), and then y i are obtained by substituting (Equation 14) into (Equation 15), and are expressed as (Equation 16) and (Equation 17), respectively.

[0083]

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[0084] (Equation 17) and (Equation 18) are differential equations with a solution of an exponential function with a time constant of αE. (Equation 17) means that the SOC of the battery 14-i during discharge converges toward 0% with a time constant of αE. x i The closer to 0%, the i The time change of x becomes small. (Equation 18) means that the SOC of the battery 14-i during charging converges toward 100% with a time constant αE. i The closer to 100%, the more i In this way, the SOC of battery 14-i changes with a common time constant αE for N batteries 14-1 to 14-N so that the change over time becomes smaller as the SOC approaches the convergence value. Therefore, the SOCs of N batteries 14-1 to 14-N converge to the same value over time. [Explanation of symbols]

[0085] 10 central control unit, 12-1 to 12-N battery management unit, 14-1 to 14-N battery, 16-1 to 16-N charge / discharge controller, 18 power transmission line, 20 load device, 22, 24, 28 communication line, 26 power source, 30 DC constant voltage source, 32 internal resistance.

Claims

1. A battery management system including a plurality of management devices each managing a charge / discharge state of a battery, the battery management device being used as each of the management devices, a charge / discharge controller connected to the battery and controlling power supplied from the battery to a load device or from a power source to the battery; and a battery agent; The battery management system includes: a central control device that determines a supply power error for the load device or the power source for the plurality of battery management devices; The battery agent measuring the state of charge of the battery; receiving the supply power error from the central controller; determining a power target value based on the state of charge and the supply power error; The charge / discharge controller includes: controlling the supply power based on the power target value; The central control unit determining a total supply power by adding up the power supplied from the plurality of battery management devices to the load device or the power supplied from the power source to the plurality of battery management devices; calculating the supply power error based on a difference between the total supply power and a required power to be supplied from each of the battery management devices to the load device or a required power to be supplied from the power source to each of the battery management devices; The battery management device is characterized in that the supplied power error is transmitted to the battery agent provided in each of the battery management devices.

2. The battery management device according to claim 1, The battery agent A battery management device that calculates the power target value that changes based on a time change rate according to the state of charge.

3. The battery management device according to claim 2, The battery agent determining a control gain in accordance with the state of charge; A control value that changes at a time rate corresponding to the control gain is obtained; A battery management device that calculates the power target value by performing limit processing on the control value to restrict a range of possible values.

4. The battery management device according to claim 3, The limiting process is When the control value is within a predetermined variable range, the power target value is calculated so as to increase or decrease in response to an increase or decrease in the control value; When the control value is outside the variable range, a battery management device is characterized in that it performs a process of determining the power target value that is constant at an upper limit value or a lower limit value in response to changes in the control value.

5. The battery management device according to any one of claims 1 to 4, the battery agent measures a value indicating the amount of charge of the battery; A battery management device, characterized in that the charge / discharge controller stops charging or discharging the battery when a value indicating the amount of charge of the battery is outside a predetermined range.

6. The battery management device according to any one of claims 1 to 4, the battery agent measures a degree of deterioration of the battery; When the deterioration level exceeds a predetermined level, the charge / discharge controller stops charging or discharging the battery.

7. The battery management device according to any one of claims 1 to 4, the battery agent measures a value indicating the amount of charge of the battery; A battery management device characterized in that the charge / discharge controller stops charging or discharging the battery when a value indicating the amount of charge of the battery matches a target value or when the difference between the value indicating the amount of charge of the battery and the target value falls within a predetermined range.

8. A battery management system including a plurality of battery management devices according to any one of claims 1 to 7, further comprising the central control device.

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