Control device and method for determining allowable output power of battery

Abstract

The present invention is a control device that determines and controls the allowable output power for a battery in a battery control system. The control device includes: a current value acquisition unit that acquires the present current value of current output from a battery cell constituting a battery; a voltage value acquisition unit that acquires the present voltage value of the battery cell; a normal allowable output power calculation unit that calculates the normal allowable output power on the basis of the present voltage value; a limiting factor determination unit that calculates a voltage drop amount on the basis of the present voltage value and the present current value, and determines a limiting factor for limiting the normal allowable output power in accordance with a temporal change amount of the voltage drop amount; a voltage decrease assessment unit that assesses whether the present voltage value has decreased to below the previous voltage value; and an allowable output power calculation unit that calculates the allowable output power by multiplying the normal allowable output power by the limiting factor when the voltage decrease assessment unit has assessed that the present voltage value has decreased to below the previous voltage value.

Description

Control device and method for determining battery output allowable power

[0001] The present invention relates to a control device and a method for determining an output allowable power of a battery, and more particularly to a control device for controlling an output allowable power of a battery and a method for determining an output allowable power of a battery.

[0002] Vehicles such as electric vehicles (EVs) and hybrid vehicles (HVs) are equipped with large-capacity, high-output batteries. The control systems for such vehicles determine the allowable output power based on the current voltage of the battery and perform control so that the output power (discharge power) from the battery or the input power (charge power) to the battery does not exceed the predetermined allowable power. Because the internal condition of the battery deteriorates depending on the vehicle's usage, etc., technologies have been proposed to prevent such deterioration.

[0003] For example, Patent Document 1 below discloses a technique for controlling the charging and discharging of a secondary battery to prevent localized deterioration inside the battery, based on a battery model that can predict the internal state.

[0004] Japanese Patent Application Laid-Open No. 2007-141558

[0005] The technology described in Patent Document 1 predicts the current state inside the battery, but does not predict the amount of voltage drop when a large current flows from or to the battery, and therefore cannot properly predict the amount of battery voltage drop. In particular, when the battery is deteriorating internally or in a harsh operating environment, the amount of battery voltage drop becomes so rapid that output voltage control cannot keep up. Furthermore, because this technology uses the actual current value from the sensor to predict the state, it is difficult to predict the amount of voltage drop when a large current flows, and it is not possible to perform control that takes into account the worst-case scenario.

[0006] SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a technique that can determine an appropriate output allowable power in accordance with the amount of change over time in the amount of voltage drop of a battery.

[0007] According to one aspect, the present invention provides a control device for determining and controlling an allowable output power of a battery in a battery control system, the control device including: a current value acquisition unit that acquires a current value of a current output from a battery cell constituting a battery; a voltage value acquisition unit that acquires a current voltage value of the battery cell; a normal output allowable power calculation unit that calculates a normal output allowable power based on the current voltage value; a limiting coefficient determination unit that calculates a voltage drop amount based on the current voltage value and the current current value and determines a limiting coefficient for limiting the normal output allowable power in accordance with a temporal change in the voltage drop amount; a voltage drop determination unit that determines whether the current voltage value has decreased from the previous voltage value; and an output allowable power calculation unit that calculates the output allowable power by multiplying the normal output allowable power by the limiting coefficient when the voltage drop determination unit determines that the current voltage value has decreased from the previous voltage value.

[0008] According to another aspect, the present invention provides a method for determining an output allowable power of a battery, the method including: acquiring a current value of a current output from a battery cell constituting the battery; acquiring a current voltage value of the battery cell; calculating a normal output allowable power based on the current voltage value; calculating a voltage drop based on the current voltage value and the current current value and calculating a change in the voltage drop amount over time; determining a limiting coefficient for limiting the normal output allowable power according to the change in the voltage drop amount over time; determining whether the current voltage value has decreased from the previous voltage value; and, if it is determined that the current voltage value has decreased from the previous voltage value, calculating the output allowable power by multiplying the normal output allowable power by the limiting coefficient.

[0009] In this specification, the term "means" does not simply mean physical means, but also includes cases where the functions of the means are realized by software. Furthermore, the functions of one means may be realized by two or more physical means, or the functions of two or more means may be realized by one physical means. Furthermore, the term "system" refers to a logical collection of multiple devices (or functional modules that realize specific functions), regardless of whether each device or functional module is contained within a single housing.

[0010] According to the present invention, an appropriate output allowable power can be determined according to the amount of change in the amount of voltage drop of the battery over time, thereby preventing the battery from outputting power exceeding the output allowable power and preventing an unintended sudden voltage drop when the battery is in use.

[0011] Other technical features, objects, and operational effects or advantages of the present invention will become apparent from the following embodiments described with reference to the accompanying drawings. The effects described in this specification are merely examples and are not intended to be limiting, and other effects may also be present.

[0012] Fig. 1 is a block diagram showing an example of a schematic configuration of a battery control system according to an embodiment of the present invention. Fig. 2 is a block diagram showing an example of a functional configuration of a control device according to an embodiment of the present invention. Fig. 3 is a graph for explaining a return amount of limited output allowable power in a control device according to an embodiment of the present invention. Fig. 4 is a flowchart for explaining an example of a process for determining output allowable power by a control device according to an embodiment of the present invention. Fig. 5 is a flowchart for explaining an example of a process for calculating a limit coefficient by a control device according to an embodiment of the present invention.

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiments described below are merely examples, and are not intended to exclude various modifications or applications of techniques not explicitly described below. The present invention can be implemented in various modifications (e.g., by combining the various embodiments) without departing from the spirit of the present invention. Furthermore, in the following description of the drawings, identical or similar parts are denoted by identical or similar reference numerals. The drawings are schematic and do not necessarily correspond to actual dimensions, ratios, etc. Parts in the drawings may have different dimensional relationships or ratios.

[0014] 1 is a block diagram showing an example of a schematic configuration of a battery control system according to an embodiment of the present invention. As shown in the figure, the battery control system 1 includes, for example, a battery pack 10, a load 20, and a control device 30. Such a battery control system 1 is mounted on a vehicle.

[0015] The battery pack 10 is a battery configured by assembling a plurality of batteries, each of which is a minimum structural unit called a unit cell. In this disclosure, following the conventional practice, the term "battery" refers to the battery configured from the entire group of unit cells (i.e., the battery pack 10), and the term "battery cell" refers to an individual unit cell. The battery is typically, but is not limited to, a lithium-ion battery.

[0016] The battery pack 10 includes various sensors 12. The sensors 12 include, for example, a voltage sensor 12a, a current sensor 12b, and a temperature sensor 12c. The voltage sensor 12a is provided for each battery cell, measures the voltage of each battery cell, and outputs the measured value (voltage V) to the control device 30. When the vehicle and its systems are operating and the battery is energized, the voltage V measured by the voltage sensor 12a is an operating voltage or closed circuit voltage (CCV). The current sensor 12b measures the value of the current output from the battery pack 10 (or the current input to the battery pack 10) and outputs the measured value (current I) to the control device 30. The temperature sensor 12c measures the temperature of a battery cell or a group of battery cells and outputs the measured value to the control device 30.

[0017] The load 20 is a high-voltage electrical device that consumes the power supplied (output) from the battery pack 10. Typically, the load 20 is a motor for driving the wheels of a vehicle. The motor is driven and controlled by an inverter circuit (not shown) under the control of the control device 30. The load 20 may also be configured to include functions as a power generation device or a power supply device. Therefore, the battery pack 10 can be charged by power supplied from the load 20 that functions as a power generation device or a power supply device.

[0018] The control device 30 controls the current or power output (supplied) from the battery pack 10 to the load 20 in the battery control system 1. The control device 30 includes a processor, a memory, an interface, and the like.

[0019] In general, the control device 30 calculates the voltage drop Δv for each battery cell based on measurement values ​​such as the voltage V and current I output from the various sensors 12 of the battery pack 10, transitions from the normal mode to the limited mode according to the amount of change over time in the calculated voltage drop Δv, and determines a limit coefficient k for the output allowable power W. The control device 30 calculates the output allowable power W based on the determined limit coefficient k, and controls the inverter of the load 20 so that power exceeding the output allowable power W is not supplied from the battery.

[0020] In the present disclosure, the temporal change in the voltage drop amount Δv refers to the amount of voltage drop per predetermined time Δt (i.e., Δv / Δt), and is sometimes referred to as the voltage drop rate. In the limited mode, the output allowable power W is more restricted than in the normal mode to prevent a sudden drop in the battery cell voltage V. That is, when the temporal change in the battery cell voltage drop amount Δv is greater than the normally expected change (state), the limit coefficient k is determined so that the output allowable power W is more restricted than normal. In other words, a region of the voltage V where the temporal change in the battery cell voltage drop amount Δv is greater than the normally expected change is a region where the behavior of the battery cell voltage V is unstable (a region where the so-called hunting phenomenon occurs). Therefore, in such a region where the behavior of the battery cell voltage V is unstable, the predetermined limit coefficient k is used to continue to further restrict the output allowable power W regardless of the temporal change in the voltage drop amount Δv, thereby promoting recovery of the battery cell (guiding the voltage drop amount Δv to an appropriate value).

[0021] Furthermore, in the limit mode, the control device 30 reduces the output allowable power W by the return amount Δw each time the battery cell voltage v approaches the normal state. This makes it possible to gradually stabilize the output state of the battery cell without immediately canceling the limit mode and transitioning to the normal mode, even when the battery cell voltage V has recovered.

[0022] 2 is a block diagram showing an example of the functional configuration of a control device according to one embodiment of the present invention. As shown in the figure, the control device 30 of this embodiment is configured to include functional components such as a measurement value acquisition unit 301, a voltage drop determination unit 302, a normal output allowable power calculation unit 303, a limit coefficient determination unit 304, a return amount determination unit 305, and an output allowable power calculation unit 306. Note that a certain functional component may be configured integrally with another functional component, or may be configured as several functional components.

[0023] The measurement value acquisition unit 301 acquires measurement values ​​measured and output by the various sensors 12 of the battery pack 10 at intervals of time. Specifically, the measurement value acquisition unit 301 acquires the current voltage V of each battery cell from the voltage sensor 12a and the current current I from the current sensor 12b, for example, every 100 ms. The current value acquisition unit and the voltage value acquisition unit are examples of specific aspects of the measurement value acquisition unit 301. The measurement value acquisition unit 301 may acquire the lowest voltage V (minimum cell voltage) among the voltages V measured at each battery cell. In this way, using the minimum cell voltage allows for stricter limitations on the output allowable power W, thereby making it possible to avoid a sudden drop in the battery output voltage, etc. The measurement value acquisition unit 301 may also acquire the current temperature of the battery from the temperature sensor 12c. The measurement value acquisition unit 301 passes the acquired measurement values ​​to the voltage drop determination unit 302 , the normal output allowable power calculation unit 303 , the limit coefficient determination unit 304 , and the return amount determination unit 305 .

[0024] The voltage drop determination unit 302 compares the acquired current voltage V with the voltage V acquired one unit time (e.g., 100 ms) earlier to determine whether or not a drop in the voltage V has occurred. The voltage drop determination unit 302 notifies the output allowable power calculation unit 306 of the result of the determination as to whether or not a drop in the voltage V has occurred. The voltage drop determination unit 302 stores the acquired current voltage V in, for example, a register (not shown) for comparison with the voltage V to be acquired at the next timing.

[0025] The normal output allowable power calculation unit 303 calculates the normal output allowable power W0 based on the voltage V acquired via the measurement value acquisition unit 301. The normal output allowable power calculation unit 303 includes, for example, a mapping table for calculating the normal output allowable power W0. That is, the normal output allowable power calculation unit 303 uses the acquired voltage V as input, refers to the mapping table, and calculates the corresponding normal output allowable power W0. The normal output allowable power calculation unit 303 may be configured to correct the normal output allowable power W0 in accordance with the measured temperature. The normal output allowable power calculation unit 303 passes the normal output allowable power W0 to the output allowable power calculation unit 306.

[0026] The limiting coefficient determination unit 304 calculates or determines a limiting coefficient k for limiting the output allowable power W based on the amount of change over time in the voltage drop amount Δv of the battery cell (i.e., Δv / Δt). The voltage drop amount Δv is calculated based on the acquired current I and the internal resistance R of the battery cell corresponding to the current I. In general, in the normal mode, the limiting coefficient determination unit 304 determines whether the amount of change over time in the calculated voltage drop amount Δv is equal to or greater than a predetermined threshold, and if it determines that the amount of change over time in the voltage drop amount Δv is equal to or greater than the predetermined threshold, determines a limiting coefficient k so as to transition the operating mode from the normal mode to the limited mode and limit the output allowable power W. In the limited mode, the limiting coefficient k has a value greater than 0 and less than 1. Whether the operating mode is the normal mode or the limited mode depends on the value of a limiting mode limiting coefficient k1, as described below. The limit coefficient k is set to either a normal mode limit coefficient k0 corresponding to the normally expected change in the voltage drop amount Δv over time, or a limit mode limit coefficient k1 when the change in the voltage drop amount Δv over time is greater than or equal to a predetermined threshold value.

[0027] Furthermore, if the limiting coefficient determination unit 304 determines that the current voltage V acquired during the limiting mode has become equal to or greater than the limiting start voltage V0, which is the voltage at the time of transition to the limiting mode, the limiting mode is released and the mode transitions to the normal mode (k1=1). On the other hand, if the limiting coefficient determination unit 304 determines that the current voltage V acquired has not returned to the limiting start voltage V0, the limiting coefficient k1 is updated so that the value of the limiting coefficient k becomes even smaller (i.e., so that the output allowable power W is further limited). In this way, when the current voltage V has returned to the limiting start voltage V0, the output allowable power W is optimized by transitioning to the normal mode.

[0028] The return amount determination unit 305 determines a return amount (relaxation amount) Δw for changing the current allowable output power W to a new allowable output power W that relaxes the restrictions on the current allowable output power W, based on the current voltage V. The normal allowable output power calculation unit 303 includes, for example, a mapping table for calculating the return amount Δw. That is, the return amount determination unit 305 inputs the acquired voltage V and references a mapping table such as the graph shown in FIG. 3 to determine the corresponding return amount Δw. For example, the return amount Δw is set to increase at a slope a from the voltage value v1(V) to v2(V) and at a slope a' (a' > a) from the voltage value v2(V) to v3(V). Furthermore, the return amount Δw is constant above the voltage value v3(V). In this way, by gradually returning the output allowable power W by the variable return amount Δw, it is possible to gradually stabilize the behavior of the battery cell voltage V when the battery cell voltage V recovers. In particular, in the region where the behavior of the battery cell voltage V is unstable (first region; less than v2 (V) in this example), the incremental change in the return amount Δw (first incremental change) is small, and in the region where the battery cell voltage V is recovering (second region; v2 to v3 (V) in this example), the incremental change in the return amount Δw (second incremental change) is large, thereby stabilizing the behavior of the battery cell voltage V. Furthermore, in the region where the battery cell voltage V has sufficiently recovered (third region; v3 (V) or higher in this example), by keeping the return amount Δw constant, it becomes possible to obtain an optimal output allowable power W according to the battery cell voltage V. The return amount determination unit 305 passes the determined return amount Δw to the output allowable power calculation unit 306.

[0029] The output allowable power calculation unit 306 determines the output allowable power W in accordance with the determination result by the voltage drop determination unit 302. That is, when the determination result by the voltage drop determination unit 302 indicates that there has been a drop in the voltage V, the output allowable power calculation unit 306 determines a new output allowable power W based on the current normal output allowable power W0 and the limit coefficient k. On the other hand, when the determination result by the voltage drop determination unit 302 indicates that there has not been a drop in the voltage V, the output allowable power calculation unit 306 determines a new output allowable power W based on the current output allowable power W and the return amount Δw. As a result, the power supplied from the battery pack 10 is controlled so as not to exceed the output allowable power W, making it possible to prevent an unintended sudden voltage drop in the battery due to an excessive supply of power.

[0030] 4 is a flowchart illustrating an example of a process for determining the output allowable power by a control device according to an embodiment of the present invention. This process is realized by the control device 30 executing a predetermined battery control program under the control of a processor, thereby cooperating with predetermined hardware resources. Through this process, the control device 30 operates to determine the output allowable power W, for example, every 100 ms.

[0031] As shown in the figure, the control device 30 acquires measurement values ​​measured by the various sensors 12 of the battery pack 10 (S401). That is, the control device 30 acquires the current voltage V of the battery cell from the voltage sensor 12a and the current current I from the current sensor 12b. The measurement value acquisition unit 301 can also acquire the current temperature T of the battery from the temperature sensor 12c.

[0032] Next, the control device 30 calculates the normal output allowable power W0 corresponding to the normally expected voltage drop Δv of the battery cell based on the acquired voltage V (S402). That is, the control device 30 uses the acquired voltage V as an input, refers to a mapping table, and calculates the corresponding normal output allowable power W0. The voltage V may be the lowest cell voltage.

[0033] Next, the control device 30 calculates a limiting coefficient k for limiting the output allowable power W (S403). The calculation of the limiting coefficient k will be described later (see FIG. 5). Next, the control device 30 determines a return amount Δw for changing the current output allowable power W to a new output allowable power W according to the current voltage V (S404). That is, as described above, the control device 30 uses the acquired voltage V as an input and refers to a mapping table such as that shown in the graph in FIG. 3, for example, to determine the corresponding return amount Δw.

[0034] Next, the control device 30 determines whether or not there has been a drop in the voltage V based on the acquired current voltage V and the voltage V one unit time ago (e.g., 100 ms) stored in the register (S405). If the control device 30 determines that there has been a drop in the voltage V (Yes in S405), it calculates a new output allowable power W (i.e., W = W0 × k) by multiplying the calculated normal output allowable power W0 by the limit coefficient k (S406).

[0035] On the other hand, if the control device 30 determines that there is no decrease in the voltage V (No in S405), it calculates a new output allowable power W (i.e., W = W0 + Δw) by adding the return amount ΔW to the current output allowable power W (S406).

[0036] In this way, the control device 30 can control the power supplied from the battery pack 10 so that it does not exceed the output allowable power W, thereby preventing an unintended sudden voltage drop when the battery is in use.

[0037] 5 is a flowchart illustrating an example of the limiting coefficient calculation process performed by the control device according to an embodiment of the present invention, showing details of the process of S403 in FIG.

[0038] That is, as shown in the figure, the control device 30 calculates the normal mode limiting coefficient k0 according to the normally expected voltage drop Δv of the battery cell based on the current voltage V. The calculation of the normal mode limiting coefficient k0 is performed using, for example, a mapping table.

[0039] Next, the control device 30 determines whether the limit mode limit coefficient k1 is 1 (S502). Here, a limit mode limit coefficient k1 of 1 indicates the normal mode, and a limit mode limit coefficient k1 less than 1 indicates the normal mode in which the output allowable power W is more restricted. If the control device 30 determines that the limit mode limit coefficient k1 is 1, i.e., that the current operating mode is the normal mode (Yes in S502), the control device 30 then determines whether the amount of change over time in the voltage drop amount Δv is equal to or greater than a predetermined threshold value (S503). Here, the amount of change over time in the voltage drop amount Δv is the amount of voltage drop per predetermined time (Δv / Δt).

[0040] If the control device 30 determines that the temporal change in the voltage drop Δv is greater than or equal to a predetermined threshold value (Yes in S503), the control device 30 stores the current voltage V as the restriction start voltage V0, for example, in a register (S504).

[0041] Next, the control device 30 calculates a limit mode limit coefficient k1 (where k1<1) corresponding to the voltage drop Δv in the limit mode based on the voltage V (S505). The limit mode limit coefficient k1 is calculated using, for example, a mapping table. Therefore, by setting the limit mode limit coefficient k1 to a value smaller than 1, the operating mode transitions from the normal mode to the limit mode.

[0042] On the other hand, when the control device 30 determines that the amount of change over time in the voltage drop amount Δv is not equal to or greater than the predetermined threshold value (No in S503), the control device 30 sets the restriction mode restriction coefficient k1 to 1 (S506). Therefore, the operation mode remains the normal mode.

[0043] Furthermore, if the control device 30 determines that the limiting coefficient k1 is not 1, i.e., that the operation mode is the limiting mode (No in S502), the control device 30 then determines whether the current voltage V is equal to or greater than the limiting start voltage V0 (S507). In other words, the control device 30 determines whether the current voltage V has returned to the limiting start voltage V0 during the limiting mode.

[0044] If the control device 30 determines that the current voltage V is equal to or greater than the start voltage V0 (Yes in S507), the control device 30 sets the limit mode limit coefficient k1 to 1 (S508). Therefore, the operation mode transitions from the limit mode to the normal mode. In other words, if the voltage V returns to the limit start voltage V0 at the time the limit mode started during the limit mode that limits the output allowable power W, it is assumed that the battery state has recovered or is recovering to the normal state, and the limit mode is released. This makes it possible to avoid limiting the output allowable power W more than necessary.

[0045] On the other hand, if the control device 30 determines that the current voltage V is not equal to or higher than the limit start voltage V0 (No in S507), it calculates the limit mode limit coefficient k1 corresponding to the voltage drop amount Δv in the limit mode in accordance with the mapping table based on the voltage V (S509). In other words, if the voltage V has not returned to the limit start voltage V0 despite being in the limit mode, the control device 30 updates the limit coefficient k1 based on the current voltage V in order to further limit the output allowable power W.

[0046] Once the normal mode restriction coefficient k0 and the restriction mode restriction coefficient k1 have been determined in this manner, the control device 30 then determines whether the restriction mode restriction coefficient k1 is equal to or greater than the normal mode restriction coefficient k0 (S510). If the control device 30 determines that the restriction mode restriction coefficient k1 is equal to or greater than the normal mode restriction coefficient k0 (Yes in S510), the control device 30 sets the restriction coefficient k to the normal mode restriction coefficient k0 (i.e., k = k0) (S511). On the other hand, if the control device 30 determines that the restriction mode restriction coefficient k1 is not equal to or greater than the normal mode restriction coefficient k0 (No in S510), the control device 30 sets the restriction coefficient k to the restriction mode restriction coefficient k1 (i.e., k = k1) (S511). In other words, the control device 30 compares the restriction mode restriction coefficient k1 with the normal mode restriction coefficient k0 and selects the smaller value (the more restrictive) as the restriction coefficient k. This allows for stricter restrictions on the output allowable power W, making it possible to prevent unintended sudden voltage drops when the battery is in use.

[0047] As described above, according to this embodiment, the system transitions to the limiting mode in accordance with the amount of change over time in the amount of voltage drop Δv of the battery cell, and the output allowable power W is limited by the limiting coefficient k, so that the output allowable power W can be limited more reliably, the recovery of the battery cell can be promoted, and an unintended sudden voltage drop of the battery cell can be prevented. In particular, according to this embodiment, the amount of change over time in the amount of voltage drop Δv of the battery cell is compared with a predetermined threshold value, so that a region in which the behavior of the voltage V of the battery cell becomes unstable can be detected, and the output allowable power W can be limited in accordance with an appropriate limiting coefficient k in the unstable region.

[0048] Furthermore, according to this embodiment, in the limit mode, the output allowable power W is gradually relaxed by a variable return amount Δw as the battery cell voltage v approaches a normal state, thereby gradually stabilizing the output state of the battery cell. In particular, in a region where the behavior of the battery cell voltage V is unstable (first region; in this example, less than v2(V)), the incremental change (first incremental change) of the return amount Δw relative to the voltage value is small, and in a region where the battery cell voltage V is recovering (second region; in this example, v2 to v3(V)), the incremental change (second incremental change) of the return amount Δw relative to the voltage value is large, thereby stabilizing the behavior of the battery cell voltage V. Furthermore, in a region where the battery cell voltage V has sufficiently recovered (third region; in this example, v3(V) or higher), the return amount Δw is kept constant relative to the voltage value, thereby making it possible to obtain an optimal output allowable power W corresponding to the battery cell voltage V.

[0049] The above-described embodiments are merely examples for explaining the present invention, and are not intended to limit the present invention to these embodiments. The present invention can be embodied in various forms without departing from the spirit of the present invention.

[0050] For example, in the methods disclosed herein, steps, operations, or functions may be performed in parallel or in a different order unless the results are inconsistent. The steps, operations, and functions described are provided merely as examples, and some of the steps, operations, and functions may be omitted or combined into one, or other steps, operations, or functions may be added, without departing from the spirit of the invention.

[0051] Furthermore, although various embodiments are disclosed in this specification, specific features (technical matters) in one embodiment can be added to or substituted for specific features in other embodiments, with appropriate modifications, and such forms are also included in the spirit of the present invention.

[0052] DESCRIPTION OF SYMBOLS 1... Battery control system 10... Battery pack 12... Sensor, 12a... Voltage sensor, 12b... Current sensor, 12c... Temperature sensor 20... Load 30... Control device 301... Measurement value acquisition unit 302... Voltage drop determination unit 303... Normal output allowable power calculation unit 304... Limit coefficient determination unit 305... Return amount determination unit 306... Output allowable power calculation unit

Claims

1. a current value acquisition unit that acquires a current value of a current output from a battery cell that constitutes the battery; a voltage value acquisition unit that acquires a current voltage value of the battery cell; a normal output allowable power calculation unit that calculates a normal output allowable power based on the current voltage value; a limiting coefficient determining unit that calculates a voltage drop amount based on the current voltage value and the current current value, and determines a limiting coefficient for limiting the normal output allowable power in accordance with a time-dependent change in the voltage drop amount; a voltage drop determination unit that determines whether the current voltage value is lower than the previous voltage value; an output allowable power calculation unit that calculates an output allowable power by multiplying the normal output allowable power by the limit coefficient when the voltage drop determination unit determines that the current voltage value has dropped below the previous voltage value, The limiting coefficient determination unit When it is determined that the amount of change in the voltage drop over time is equal to or greater than a predetermined threshold value in the normal mode, the normal mode is switched to a limit mode, and a limit mode limit coefficient is calculated based on the voltage value; determining the limiting factor based on the limit mode limiting factor; A control device in a battery control system.

2. The limiting coefficient determination unit When the current voltage value is smaller than the voltage value at the time of transition from the normal mode to the limit mode in the limit mode, the limit mode limit coefficient is calculated based on the current voltage value so that the normal output allowable power is further limited; determining the limiting factor based on the limit mode limiting factor; The control device according to claim 1 .

3. the limiting coefficient determination unit transitions from the limiting mode to the normal mode when, in the limiting mode, the current voltage value is equal to or greater than the voltage value at the time of transition from the normal mode to the limiting mode; The control device according to claim 1 .

4. the limiting coefficient determination unit calculates a normal mode limiting coefficient based on the voltage value in the normal mode; When the restriction mode restriction coefficient is equal to or greater than the normal mode restriction coefficient, the normal mode restriction coefficient is determined as the restriction coefficient, and when the restriction mode restriction coefficient is smaller than the normal mode restriction coefficient, the restriction mode restriction coefficient is determined as the restriction coefficient. The control device according to claim 1 .

5. a return amount determination unit that variably determines a return amount according to the current voltage value; the output allowable power calculation unit calculates new output allowable power by reducing the current output allowable power by the return amount when the voltage drop determination unit determines that the current voltage value is not lower than the previous voltage value. The control device according to claim 1 .

6. the return amount determination unit determines the return amount to be a first incremental change with respect to the current voltage when the current voltage value is within a first region, and determines the return amount to be a second incremental change with respect to the current voltage that is larger than the first incremental change when the current voltage value is within a second region that is a voltage value higher than the first region. The control device according to claim 5 .

7. the return amount determination unit determines a constant return amount for the current voltage when the current voltage value is within a third region; The control device according to claim 6.

8. the voltage value acquired by the voltage value acquisition unit is the lowest voltage value among the plurality of battery cells; The control device according to claim 1 .

9. 1. A method for determining an output power allowance of a battery, comprising: Obtaining a current value of a current output from a battery cell that constitutes the battery; Obtaining a current voltage value of the battery cell; calculating a normal output allowable power based on the current voltage value; calculating a voltage drop amount based on the current voltage value and the current current value, and calculating a time change amount of the voltage drop amount; determining a limiting coefficient for limiting the normal output allowable power in accordance with a time-dependent change in the amount of voltage drop; determining whether the current voltage value has decreased from the previous voltage value; calculating an output allowable power by multiplying the normal output allowable power by the limit coefficient when it is determined that the current voltage value is lower than the previous voltage value; Determining the limiting factor comprises: When it is determined that the amount of change over time of the voltage drop is equal to or greater than a predetermined threshold value in the normal mode, the normal mode is switched to a limit mode, and a limit mode limit coefficient is calculated based on the voltage value; determining the limiting factor based on the limiting mode limiting factor. method.