Control device and method for determining allowable output power of battery

Abstract

The present invention comprises: a current measurement unit that measures the current value of a current outputted from a battery; a voltage measurement unit that measures the voltage value of the battery; a first voltage drop amount calculation unit that calculates a first voltage drop amount of the battery on the basis of an open circuit voltage based on the current value and the voltage value; an actual discharge voltage calculation unit that calculates an actual discharge voltage of the battery cell on the basis of the first voltage drop amount; a first voltage drop amount calculation unit that calculates a second voltage drop amount of the battery when it is assumed, on the basis of the actual discharge voltage, that a prescribed current has flowed for a prescribed time; a virtual discharge voltage calculation unit that calculates the virtual discharge voltage of the battery on the basis of the second voltage drop amount; a resistance value calculation unit that calculates a virtual resistance value of the battery on the basis of the virtual discharge voltage; and a first allowable output power calculation unit that calculates a first allowable output power on the basis of the virtual resistance 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] Therefore, an object of the present invention is to provide a technology that can appropriately predict the amount of voltage drop according to the internal state of the battery and accurately calculate the output allowable power based on the predicted amount of voltage drop.

[0007] According to one aspect, the present invention provides a control device for determining and controlling an output allowable power of a battery in a battery control system, the control device including: a current measurement unit that measures a current value output from a battery cell constituting the battery; a voltage measurement unit that measures a voltage value of the battery cell; a first voltage drop amount calculation unit that calculates a first voltage drop amount of the battery cell based on the measured current value and an open circuit voltage based on the measured voltage value; an actual discharge voltage calculation unit that calculates an actual discharge voltage of the battery cell based on the calculated first voltage drop amount; a first voltage drop amount calculation unit that calculates a second voltage drop amount of the battery cell when a predetermined current is assumed to flow for a predetermined time based on the calculated actual discharge voltage; a virtual discharge voltage calculation unit that calculates a virtual discharge voltage of the battery cell based on the calculated second voltage drop amount; a resistance value calculation unit that calculates a virtual resistance value of the battery cell based on the calculated virtual discharge voltage; and a first output allowable power calculation unit that calculates a first output allowable power based on the calculated virtual resistance value.

[0008] According to another aspect, the present invention provides a method for determining an output allowable power of a battery, the method including: measuring a current value of a current output from a battery cell constituting the battery and measuring a voltage value of the battery cell, calculating a first voltage drop amount of the battery cell based on the measured current value and an open circuit voltage based on the measured voltage value, calculating an actual discharge voltage of the battery cell based on the calculated first voltage drop amount, calculating a second voltage drop amount of the battery cell when a predetermined current is assumed to flow for a predetermined time based on the calculated actual discharge voltage, calculating a virtual discharge voltage of the battery cell based on the calculated second voltage drop amount, calculating a virtual resistance value of the battery cell based on the calculated virtual discharge voltage, and determining an output allowable power based on the calculated virtual resistance value.

[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, it is possible to appropriately predict the amount of voltage drop according to the internal state of the battery, and to accurately calculate the output allowable power based on the predicted amount of voltage drop, thereby preventing the battery from outputting power exceeding the output allowable power and preventing battery degradation.

[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 diagram for explaining calculation of the internal resistance value of a battery by a control device according to an embodiment of the present invention. Fig. 4 is a diagram for explaining a method for calculating the amount of voltage drop of a battery by a control device according to an embodiment of the present invention. Fig. 5 is a flowchart for explaining an example of processing for determining an output allowable power 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 value) to the control device 30. When the vehicle and its systems are operating and the battery is energized, the voltage value measured by the voltage sensor 12a is the operating voltage or closed circuit voltage (CCV). As described below, the open circuit voltage (OCV) is calculated using the closed circuit voltage CCV to calculate the voltage drop of the battery cell. 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 value) 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 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 load 20 may also include functions as a power generation device or a power supply device. Therefore, the battery pack 10 can be charged by the 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 of the battery pack 10 in the battery control system 1. Specifically, the control device 30 appropriately predicts the internal state of the battery cells and / or the battery based on measurement values ​​output from the various sensors 12 of the battery pack 10, determines the output allowable power based on the predicted amount of voltage drop, and controls the load 20 so that it does not operate beyond the output allowable power. The control device 30 is configured to include a processor, a memory, an interface, etc.

[0019] 2 is a block diagram showing an example of the functional configuration of a control device according to an embodiment of the present invention. As shown in the figure, the control device 30 of this embodiment includes functional components such as a measurement value acquisition unit 301, an open circuit voltage calculation unit (hereinafter referred to as the "OCV calculation unit") 302, a first voltage drop amount calculation unit 303, an actual discharge voltage calculation unit 304, a second voltage drop amount calculation unit 305, a virtual discharge voltage calculation unit 306, a resistance value calculation unit 307, a first output allowable power calculation unit 308, a second output allowable power calculation unit 309, and an output allowable power determination unit 310. Note that a certain functional component may be configured integrally with another functional component, or may be configured as several functional components.

[0020] The measurement value acquisition unit 301 acquires measurement values ​​measured and output by the various sensors 12 of the battery pack 10. Specifically, the measurement value acquisition unit 301 acquires the current voltage value (closed circuit voltage CCV) of the battery cell from the voltage sensor 12a, and acquires the current current I from the current sensor 12b. The measurement value acquisition unit 301 also acquires the current temperature of the battery from the temperature sensor 12c. The measurement value acquisition unit 301 passes these acquired measurement values ​​to the OCV calculation unit 302 and the second output allowable power calculation unit 309.

[0021] The OCV calculation unit 302 calculates the current open circuit voltage OCV of the battery cell based on the closed circuit voltage CCV and the current I acquired via the measurement value acquisition unit 301. Specifically, the OCV calculation unit 302 calculates the open circuit voltage OCV using the following formula: OCV=CCV+I×R where R is the internal impedance of the battery cell caused by the current I. Note that the OCV calculation unit 302 may be configured to correct the resistance value R based on temperature when calculating the OCV.

[0022] The first voltage drop amount calculation unit 303 calculates a first voltage drop amount ΔV1 based on the current I and the open circuit voltage OCV. The first voltage drop amount ΔV1 indicates the amount of voltage drop after a predetermined unit time, calculated based on the current I. The first voltage drop amount calculation unit 303 includes a first voltage drop amount calculation model (not shown) for calculating the first voltage drop amount ΔV1. The first voltage drop amount calculation model is configured to calculate the voltage drop amount ΔV1 for each circuit of the battery cell. This makes it possible to accurately calculate the first voltage drop amount ΔV1 for each battery cell circuit. The first voltage drop amount calculation model is configured to use the first voltage drop amount ΔV1 from a past time (e.g., one unit time ago) (referred to as ΔV1(n-1)) to calculate the current first voltage drop amount ΔV1 (referred to as ΔV1(n)). The unit time is a calculation period used by the processor of the control device 30 to determine the output allowable power, and is, for example, 100 ms, but is not limited to this. 4 , the first voltage drop amount calculation unit 303 uses a first voltage drop amount calculation model to calculate the current first voltage drop amount ΔV1(n) based on the first voltage drop amount ΔV1(n-1) calculated one unit time ago (one unit time ago) and the first voltage drop amount ΔV1_100ms(n) that has dropped during one unit time (e.g., 100 ms) calculated based on the current current I, according to the following formula: ΔV1(n)=ΔV1(n-1)+ΔV1_100ms(n) Then, the first voltage drop amount calculation unit 303 passes the calculated first voltage drop amount ΔV1 to the actual discharge voltage calculation unit 304.

[0023] The actual discharge voltage calculation unit 304 calculates the actual discharge voltage V1 of the battery cell based on the calculated open circuit voltage OCV and the current first voltage drop amount ΔV1. That is, the actual discharge voltage calculation unit 304 calculates the actual discharge voltage V1 using the following formula: V1=OCV−ΔV1 The actual discharge voltage calculation unit 304 passes the calculated actual discharge voltage V1 to the second voltage drop amount calculation unit 305.

[0024] The second voltage drop amount calculation unit 305 uses the calculated actual discharge voltage V1 as an initial value and calculates a sufficiently large predetermined current I ＬThe second voltage drop amount calculation unit 305 calculates a second voltage drop amount ΔV2 when it is assumed that a predetermined current I Ｌ For example, in the case of a battery mounted on a vehicle, the current I is about 400 A or more, and may be the maximum current allowed by the specifications of the battery control system 1. Ｌ is a value greater than the measured current I. The predetermined time is a time sufficiently longer than the above-mentioned one unit time, for example, 2 seconds, but is not limited to this. The second voltage drop amount calculation unit 305 includes a first voltage drop amount calculation model (not shown) for calculating the second voltage drop amount ΔV2. The second voltage drop amount calculation model is configured to calculate the voltage drop amount ΔV2 for each circuit of the battery cell. This makes it possible to calculate an accurate second voltage drop amount ΔV2 for each battery cell circuit. The second voltage drop amount calculation model is configured to use a second voltage drop amount ΔV2 from a past time (for example, one unit time ago) (denoted as ΔV1(n-1)) to calculate the current second voltage drop amount ΔV2 (denoted as ΔV2(n)).

[0025] Specifically, the first voltage drop amount calculation unit 303 uses the second voltage drop amount calculation model to calculate the current second voltage drop amount ΔV2(n) based on the current first voltage drop amount ΔV1(n) and the second voltage drop amount ΔV2_2s(n) after a predetermined time (for example, 2 seconds) calculated based on the current I, according to the following formula: ΔV2(n)=ΔV2(n-1)+ΔV2_2s(n)=ΔV1(n)+ΔV2_2s(n) In other words, in the present disclosure, the current first voltage drop amount ΔV1(n) is used to calculate the second voltage drop amount ΔV2, instead of the previous second voltage drop amount ΔV2(n-1). As a result, the current second voltage drop amount ΔV2 is calculated based on the predetermined current I. Ｌ The second voltage drop amount calculation unit 305 transfers the calculated second voltage drop amount ΔV2 to the virtual discharge voltage calculation unit 306.

[0026] The virtual discharge voltage calculation unit 306 calculates a virtual discharge voltage V2 of the battery cell based on the calculated open circuit voltage OCV, the first voltage drop amount ΔV1, and the second voltage drop amount ΔV2. That is, the virtual discharge voltage calculation unit 306 calculates the virtual discharge voltage V2 using the following formula: V2=OCV−(ΔV1+ΔV2) The virtual discharge voltage calculation unit 306 passes the calculated virtual discharge voltage V2 to the resistance value calculation unit 307.

[0027] The resistance value calculation unit 307 calculates the resistance value based on the measured and acquired voltage CCV (which is assumed to be voltage V0), the virtual discharge voltage V2, the current I, and the predetermined current I Ｌ That is, the resistance value calculation unit 307 calculates the virtual resistance R' using the following formula: R'=(V0-V2) / (I-I Ｌ That is, the calculated virtual resistance R' is the internal impedance when ion diffusion in the internal state of the battery cell increases (deteriorates), and is calculated by applying a predetermined current I for a predetermined time. Ｌ The calculated virtual resistance R′ is passed to the first output allowable power calculation unit 308.

[0028] The first output allowable power calculation unit 308 calculates the first output allowable power W1 based on the calculated virtual resistance R'. The first output allowable power calculation unit 308 includes, for example, a mapping table for calculating the first output allowable power W1. That is, the first output allowable power calculation unit 308 receives the calculated virtual resistance R' as input and calculates the corresponding first output allowable power W1. The first output allowable power calculation unit 308 may be configured to correct the resistance R in accordance with the measured temperature. The first output allowable power calculation unit 308 passes the first output allowable power W1 to the output allowable power determination unit 310.

[0029] The second output allowable power calculation unit 309 calculates the resistance R of the battery cell based on the current I acquired via the measurement value acquisition unit 301, and further calculates the second output allowable power W2 based on the calculated resistance R. The second output allowable power calculation unit 309 includes, for example, a mapping table for calculating the second output allowable power W2. That is, the second output allowable power calculation unit 309 receives the calculated resistance R as input and calculates the corresponding second output allowable power W2. The second output allowable power calculation unit 309 may be configured to correct the resistance R in accordance with the measured temperature. The second output allowable power calculation unit 309 passes the second output allowable power W2 to the output allowable power determination unit 310. Note that the second output allowable power calculation unit 309 is an optional component.

[0030] The output allowable power determination unit 310 determines the output allowable power W based on the result of comparison between the first output allowable power W1 and the second output allowable power W2. That is, the output allowable power determination unit 310 compares the first output allowable power W1 and the second output allowable power W2 and determines the smaller value as the output allowable power W. The output allowable power determination unit 310 controls the power supplied from the battery pack 10 so that it does not exceed the output allowable power W. This allows the battery control system 1 to supply a predetermined current I Ｌ (For example, maximum current I ＭＡＸ ) flows, the battery pack 10 can be protected and deterioration can be suppressed. If the second output allowable power calculation unit 309 is omitted, the first output allowable power W1 calculated by the first output allowable power calculation unit 308 becomes the output allowable power W.

[0031] 5 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, for example, every 100 ms.

[0032] As shown in the figure, the control device 30 acquires measurement values ​​measured by the various sensors 12 of the battery pack 10 (S501). That is, the control device 30 acquires the current voltage value (closed circuit voltage CCV) of the battery cell from the voltage sensor 12a and the current current I from the current sensor 12b. In addition, the measurement value acquisition unit 301 can acquire the current temperature T of the battery from the temperature sensor 12c.

[0033] Next, the control device 30 calculates the current open circuit voltage OCV based on the acquired voltage CCV and current I (S502). That is, the control device 30 calculates the open circuit voltage OCV using the internal impedance of the battery caused by the current I.

[0034] Next, the control device 30 calculates a first voltage drop amount ΔV1 using a first voltage drop amount calculation model based on the current I and the open-circuit voltage OCV (S503). In this case, the control device 30 uses the first voltage drop amount ΔV1(n-1) calculated one unit time earlier (100 ms in this example) to calculate the current first voltage drop amount ΔV1(n). Next, the control device 30 calculates an actual discharge voltage V1 based on the calculated open-circuit voltage OCV and the current first voltage drop amount ΔV1 (S504).

[0035] Next, the control device 30 sets the calculated actual discharge voltage V1 as an initial value, and calculates a predetermined current I Ｌ The control device 30 calculates a second voltage drop amount ΔV2 based on the calculated open circuit voltage OCV, the first voltage drop amount ΔV1, and the second voltage drop amount ΔV2, which are assumed to occur when a current (e.g., a maximum current) flows for a predetermined time using the second voltage drop amount calculation model (S505). The predetermined time is, for example, two seconds. Next, the control device 30 calculates a virtual discharge voltage V2 based on the calculated open circuit voltage OCV, the first voltage drop amount ΔV1, and the second voltage drop amount ΔV2 (S506).

[0036] Next, the control device 30 calculates the output voltage % based on the calculated open circuit voltage OCV, the virtual discharge voltage V2, the current I, and the predetermined current I Ｌ In other words, the control device 30 calculates the virtual resistance R′ based on the predetermined current I Ｌ A virtual resistance R' is estimated from a margin for the amount of voltage drop when current flows.

[0037] Next, the control device 30 calculates the first output allowable power W1 based on the calculated virtual resistance R' using a predetermined mapping table (S508). The control device 30 may be configured to correct the resistance R' in accordance with the measured temperature.

[0038] Furthermore, control device 30 calculates first output allowable power W2 using a predetermined mapping table based on battery resistance R calculated based on current I (S509).

[0039] Next, the control device 30 determines whether the first output allowable power W1 calculated as described above is equal to or greater than the second output allowable power W2 (S510). If the control device 30 determines that the first output allowable power W1 is smaller than the second output allowable power W2 (No in S510), the control device 30 determines the first output allowable power W1 as the output allowable power W (S511). In other words, the output allowable power W is determined based on the predetermined current I Ｌ is the output allowable power based on the virtual resistance R' obtained when it is assumed that the first output allowable power W1 flows for a predetermined period of time. On the other hand, when the control device 30 determines that the first output allowable power W1 is equal to or greater than the second output allowable power W2 (Yes in S510), the control device 30 determines the second output allowable power W2 as the output allowable power W (S512). The control device 30 controls the power supplied from the battery pack 10 so that it does not exceed the output allowable power W.

[0040] As described above, according to this embodiment, the second voltage drop amount ΔV2 is predicted when it is assumed that a current larger than the current current I flows through the battery control system 1 for a predetermined time, and therefore, it is possible to determine a more accurate output allowable power W based on the predicted second voltage drop amount ΔV2. In particular, according to this embodiment, it is possible to determine a predetermined current I that is sufficiently large and allowed by the specifications. Ｌ By predicting the second voltage drop amount ΔV2 using (maximum current), it is possible to anticipate the worst conditions when the vehicle is running, and it is possible to determine the optimum output allowable power W under any circumstances.

[0041] Furthermore, according to this embodiment, by using the current that is actually measured and acquired, it is possible to predict the second voltage drop amount ΔV2 that would occur if a large current flowed from the current battery state. In this case, when calculating the second voltage drop amount ΔV2, the current first voltage drop amount ΔV1(n) is used instead of the previous second voltage drop amount ΔV2(n-1). This takes the current battery state into consideration, making it possible to calculate the second voltage drop amount ΔV2 more accurately.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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...Open circuit voltage calculation unit (OCV calculation unit) 303...First voltage drop amount calculation unit 304...Actual discharge voltage calculation unit 305...Second voltage drop amount calculation unit 306...Virtual discharge voltage calculation unit 307...Resistance value calculation unit 308...First output allowable power calculation unit 309...Second output allowable power calculation unit 310...Output allowable power determination unit

Claims

1. a current measurement unit that measures a current value of a current output from a battery cell that constitutes the battery; a voltage measurement unit that measures a voltage value of the battery cell; a first voltage drop amount calculation unit that calculates a first voltage drop amount of the battery cell based on an open circuit voltage that is based on the measured current value and the measured voltage value; an actual discharge voltage calculation unit that calculates an actual discharge voltage of the battery cell based on the calculated first voltage drop amount; a second voltage drop amount calculation unit that calculates a second voltage drop amount of the battery cell when a predetermined current is assumed to flow for a predetermined time based on the calculated actual discharge voltage; a virtual discharge voltage calculation unit that calculates a virtual discharge voltage of the battery cell based on the calculated second voltage drop amount; a resistance value calculation unit that calculates a virtual resistance value of the battery cell based on the calculated virtual discharge voltage; a first output allowable power calculation unit that calculates a first output allowable power based on the calculated virtual resistance value, A control device in a battery control system.

2. the predetermined current is a maximum current allowed by the specifications of the battery control system; The control device according to claim 1 .

3. the first voltage drop amount calculation unit calculates the current first voltage drop amount based on the current current value and the first voltage drop amount calculated a unit time ago; The control device according to claim 1 .

4. the second voltage drop amount calculation unit calculates the current second voltage drop amount based on the current first voltage drop amount, instead of the second voltage drop amount calculated a unit time ago; The control device according to claim 3 .

5. The predetermined time is longer than the unit time. The control device according to claim 3 .

6. the resistance value calculation unit calculates the virtual resistance value based on the measured current value, the open circuit voltage, the predetermined current, and the virtual discharge voltage. The control device according to claim 1 .

7. a second output allowable power calculation unit that calculates a second output allowable power based on the current and the open circuit voltage; an output allowable power determination unit that determines an output allowable power of the battery control system based on the calculated first output allowable power and the calculated second output allowable power. The control device according to claim 1 .

8. the output allowable power determiner compares the first output allowable power with the second output allowable power and determines the smaller value as the output allowable power; The control device according to claim 7.

9. 1. A method for determining an output power allowance of a battery, comprising: measuring a current value of a current output from a battery cell constituting the battery and measuring a voltage value of the battery cell; Calculating a first voltage drop amount of the battery cell based on an open circuit voltage that is based on the measured current value and the measured voltage value; Calculating an actual discharge voltage of the battery cell based on the calculated first voltage drop amount; Calculating a second voltage drop amount of the battery cell when a predetermined current is assumed to flow for a predetermined time based on the calculated actual discharge voltage; Calculating a virtual discharge voltage of the battery cell based on the calculated second voltage drop amount; Calculating a virtual resistance value of the battery cell based on the calculated virtual discharge voltage; determining an output allowable power based on the calculated virtual resistance value. method.