Control device and method for determining output allowable power of battery

Abstract

The present invention is provided with: a current measurement unit that measures the current value of a current output from a battery; a voltage measurement unit that measures a 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 obtained on the basis of 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, on the basis of the actual discharge voltage, a second voltage drop amount of the battery assuming that a predetermined current flows for a predetermined time; a virtual discharge voltage calculation unit that calculates a 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 output permissible power calculation unit that calculates a first output permissible power on the basis of the virtual resistance value.

Description

TECHNICAL FIELD

[0001] The present application relates to a control device and a method of determining an output allowable power of a battery, and particularly relates to a control device and a method of determining an output allowable power of a battery. BACKGROUND

[0002] A large-capacity and large-output battery is mounted in a vehicle such as an electric vehicle (EV) or a hybrid vehicle (HV). A control system of such a vehicle determines an output allowable power in accordance with a current voltage of the battery, and controls an output power (discharge power) from the battery or an input power (charge power) to the battery so as not to exceed the prescribed allowable power. Since the internal state of the battery deteriorates due to the use condition of the vehicle or the like, a technology of preventing such deterioration has been proposed.

[0003] For example, Patent Literature 1 below discloses a technology of performing charge and discharge control of a secondary battery for preventing local deterioration in the inside of the battery, based on a battery model capable of predicting the internal state.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: Japanese Patent Application Publication No. 2007-141558 SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] The technology described in Patent Literature 1 above is for predicting the current state in the inside of the battery, and is not for predicting the amount of voltage drop when a large current flows from or to the battery, and cannot appropriately predict the amount of voltage drop of the battery. Especially in a case where the deterioration in the inside of the battery is progressing, or in a case where the use environment is harsh, the amount of voltage drop of the battery is drastic, and the control of the output voltage is not performed in time. In addition, since this technology predicts the state using the actual current value from the sensor, it is difficult to predict the amount of voltage drop when a large current flows, and the control assuming the worst condition cannot be performed.

[0009] Therefore, an object of the present application is to provide a technology capable of appropriately predicting the amount of voltage drop in accordance with the internal state of the battery, and calculating the output allowable power with high precision based on the predicted amount of voltage drop.

[0010] MEANS FOR SOLVING THE PROBLEMS

[0011] The application according to one aspect is a control device that determines and controls an output allowable power of a battery in a battery control system. The control device includes: 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, the open circuit voltage being obtained based on the measured current value and 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, assuming that a prescribed current has flowed for a prescribed 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.

[0012] In addition, the application according to another aspect is a method of determining an output allowable power of a battery. The method includes: measuring a current value of a current output from a battery cell that constitutes 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, the open circuit voltage being obtained based on the measured current value and 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, assuming that a prescribed current has flowed for a prescribed 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.

[0013] Further, in this specification and the like, a unit can be a physical unit, and can also be a functional unit that includes a case where the functional unit is implemented by software. In addition, the functional unit of one unit can be implemented by two or more physical units, and the functional units of two or more units can be implemented by one physical unit. In addition, a "system" refers to a logical collection of a plurality of devices (or functional modules that implement a specific function), and is independent of whether the devices, the functional modules are present in a single housing or not.

[0014] Effects of the Invention

[0015] According to the present application, the voltage drop amount can be appropriately predicted in accordance with the internal state of the battery, so the output allowable electric power can be calculated with high precision on the basis of the predicted voltage drop amount. Thus, the electric power by which the battery output exceeds the output allowable electric power can be suppressed, so the deterioration of the battery can be prevented.

[0016] Other technical features, objects, and effects of the present application will become apparent from the following embodiments described in reference to the accompanying drawings. The effects described in the present specification are merely illustrative or illustrative, and the present application can have additional effects. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a block diagram showing an example of the outline structure of a battery control system according to an embodiment of the present application.

[0018] Figure 2 is a block diagram showing an example of the functional structure of a control device according to an embodiment of the present application.

[0019] Figure 3 is a graph for explaining the calculation of the internal resistance value of a battery by a control device according to an embodiment of the present application.

[0020] Figure 4 is a graph for explaining the calculation method of the voltage drop amount of a battery by a control device according to an embodiment of the present application.

[0021] Figure 5 is a flowchart showing an example of the process for determining the output allowable electric power by a control device according to an embodiment of the present application. DETAILED DESCRIPTION

[0022] Hereinafter, embodiments of the present application will be described with reference to the accompanying drawings. However, the embodiments to be described below are merely examples, and are not intended to exclude various modifications, applications of technology, and the like, which are not explicitly shown below. The present application can be implemented in various modifications (for example, combination of the embodiments, and the like) without departing from the spirit of the present application. In addition, in the description of the accompanying drawings below, the same or similar parts are denoted by the same or similar reference numerals to represent. The drawings are schematic, and do not necessarily agree with the actual dimensions, ratios, and the like. There are sometimes parts that differ in the dimensional relationship, ratio, and the like between the drawings.

[0023] Figure 1 is a block diagram showing an example of the outline structure of a battery control system according to an embodiment of the present application. As shown in the drawing, the battery control system 1 is configured to include, 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.

[0024] The battery pack 10 is a battery configured by collecting a plurality of cells called unit cells as the smallest unit. In the present disclosure, the term "battery" is used conventionally to mean a battery (i.e., the battery pack 10) configured by a group of unit cells as a whole. The term "battery cell" is used to mean each unit cell. The battery is typically a lithium-ion battery, but is not limited thereto.

[0025] The battery pack 10 is configured to include 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. The voltage value measured by the voltage sensor 12a is the operating voltage or the closed-circuit voltage (CCV) in a state in which the vehicle and its systems are operating and the battery is powered on. As described later, the closed-circuit voltage CCV is used to calculate the open-circuit voltage (OCV) to calculate the voltage drop amount of the battery cell. The current sensor 12b measures the value of the current (or the current input to the battery pack 10) output from the battery pack 10, and outputs the measured value (current value) to the control device 30. The temperature sensor 12c measures the temperature of the battery cell or a group of several battery cells, and outputs the measured value to the control device 30.

[0026] The load 20 is a heavy electrical equipment that consumes the electric power supplied (output) from the battery pack 10. Typically, the load 20 is a motor for driving the wheels of the vehicle. In addition, the load 20 can be configured to include the function as a power generation device, a power supply device. Thus, the battery pack 10 can be charged by the electric power supplied from the load 20 as a power generation device, a power supply device.

[0027] The control device 30 controls the current or the electric 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 cell and / or the battery based on the measured values output from the various sensors 12 of the battery pack 10, determines the output allowable electric power based on the predicted voltage drop amount, and controls the load 20 to operate without exceeding the output allowable electric power. The control device 30 is configured to include a processor, a memory, an interface, and the like.

[0028] Figure 2is a block diagram showing an example of a functional configuration of a control device according to an embodiment of the present application. As shown in the drawing, the control device 30 according to the present embodiment is configured to include a measurement value acquisition section 301, an open-circuit voltage calculation section (hereinafter referred to as "OCV calculation section") 302, a first voltage drop amount calculation section 303, an actual discharge voltage calculation section 304, a second voltage drop amount calculation section 305, a virtual discharge voltage calculation section 306, a resistance value calculation section 307, a first output allowable power calculation section 308, a second output allowable power calculation section 309, and an output allowable power decision section 310 as functional configuration elements. Note that a certain functional configuration element can be configured integrally with another functional configuration element, or can be configured to be divided into several functional configuration elements.

[0029] The measurement value acquisition section 301 acquires measurement values measured and output by the various sensors 12 of the battery pack 10. Specifically, the measurement value acquisition section 301 acquires a current voltage value (closed-circuit voltage CCV) of the battery cell from the voltage sensor 12a, and acquires a current current I from the current sensor 12b. In addition, the measurement value acquisition section 301 acquires a current temperature of the battery from the temperature sensor 12c. The measurement value acquisition section 301 transmits these acquired measurement values to the OCV calculation section 302 and the second output allowable power calculation section 309.

[0030] The OCV calculation section 302 calculates a current open-circuit voltage OCV of the battery cell on the basis of the closed-circuit voltage CCV and the current I acquired via the measurement value acquisition section 301. Specifically, the OCV calculation section 302 calculates the open-circuit voltage OCV in accordance with the following equation.

[0031] OCV = CCV + I x R

[0032] where R is an internal resistance of the battery cell caused by the current I.

[0033] In addition, the OCV calculation section 302 can also be configured to correct the resistance value R by temperature when calculating the OCV.

[0034] The first voltage drop amount calculating section 303 calculates a first voltage drop amount AV1 based on the current I and the open circuit voltage OCV. The first voltage drop amount AV1 indicates a voltage drop amount after a prescribed unit time based on the current I. The first voltage drop amount calculating section 303 includes a first voltage drop amount calculating model (not shown) for calculating the first voltage drop amount AV1. The first voltage drop amount calculating model is configured to calculate the voltage drop amount AV1 of the circuit of each battery cell. Thereby, an accurate first voltage drop amount AV1 can be calculated for each battery cell circuit. The first voltage drop amount calculating model is configured to calculate the current first voltage drop amount AV1 (set as AV1(n)) using the past (for example, one unit time ago) first voltage drop amount AV1 (set as AV1(n-1)). The unit time is an operation period of the processor of the control device 30 for deciding the output allowable power, for example, 100 ms, but is not limited thereto. Specifically, as shown in FIG. 3, the first voltage drop amount calculating section 303 uses the first voltage drop amount calculating model to calculate the current first voltage drop amount AV1 (n) based on the first voltage drop amount AV1 (n-1) calculated the previous time (one unit time ago) and the first voltage drop amount AV1_100ms(n) dropped during one unit time (for example, 100 ms) calculated based on the current I according to the following equation. Figure 4

[0035] AV1(n) = AV1(n-1) + AV1_100ms(n)

[0036] Further, the first voltage drop amount calculating section 303 transmits the calculated first voltage drop amount AV1 to the actual discharge voltage calculating section 304.

[0037] The actual discharge voltage calculating section 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 AV1. That is, the actual discharge voltage calculating section 304 calculates the actual discharge voltage V1 using the following equation.

[0038] V1 = OCV - AV1

[0039] The actual discharge voltage calculating section 304 transmits the calculated actual discharge voltage V1 to the second voltage drop amount calculating section 305.

[0040] The second voltage drop amount calculating section 305 calculates a second voltage drop amount AV2 assuming that a prescribed current I L flows for a prescribed time. In the second voltage drop amount calculating section 305, the second voltage drop amount AV2 is calculated based on the actual discharge voltage V1 calculated by the actual discharge voltage calculating section 304 and the prescribed current I L ​For example, in the case of a battery mounted on a vehicle, the specified current I is approximately 400A or above, and may be the maximum current allowed by the battery control system 1 in terms of specifications. L It is a value greater than the measured current I. The prescribed time is a time that is sufficiently long compared to the above-mentioned one unit time, for example, 2 seconds, but not limited thereto. The second voltage drop calculation unit 305 includes a first voltage drop calculation model (not shown) for calculating the second voltage drop ΔV2. The second voltage drop calculation model is configured to calculate the voltage drop ΔV2 of the circuit of each battery cell. Thus, an accurate second voltage drop ΔV2 can be calculated for each battery cell circuit. The second voltage drop calculation model is configured to use the second voltage drop ΔV2 (set to ΔV1(n-1)) in the past (for example, one unit time ago) to calculate the current second voltage drop ΔV2 (set to ΔV2(n)).

[0041] Specifically, the first voltage drop calculation unit 303 uses the second voltage drop calculation model to calculate the current second voltage drop ΔV2(n) based on the current first voltage drop ΔV1(n) and the second voltage drop ΔV2_2s(n) after a specified time (for example, 2 seconds) calculated based on the current I, according to the following formula.

[0042] ΔV2(n)=ΔV2(n-1)+ΔV2_2s(n)

[0043] =ΔV1(n)+ΔV2_2s(n)

[0044] That is, in the present disclosure, the calculation of the second voltage drop ΔV2 uses the current first voltage drop ΔV1(n) instead of the previous second voltage drop ΔV2(n-1). L The voltage drop amount after the predetermined time has passed is replaced with the current battery voltage drop amount. The second voltage drop amount calculation unit 305 transmits the calculated second voltage drop amount ΔV2 to the pseudo discharge voltage calculation unit 306 .

[0045] The virtual discharge voltage calculator 306 calculates the virtual discharge voltage V2 of the battery cell based on the calculated open circuit voltage OCV, the first voltage drop ΔV1, and the second voltage drop ΔV2. Specifically, the virtual discharge voltage calculator 306 calculates the virtual discharge voltage V2 using the following equation.

[0046] V2=OCV-(ΔV1+ΔV2)

[0047] The virtual discharge voltage calculation section 306 passes the calculated virtual discharge voltage V2 to the resistance value calculation section 307.

[0048] The resistance value calculation section 307 calculates a virtual resistance R' based on the measured and acquired voltage CCV (set as voltage V0), the virtual discharge voltage V2, the current I, and a prescribed current I L flowed for a prescribed time. That is, the resistance value calculation section 307 calculates the virtual resistance R' using the following equation.

[0049] R' = (V0 - V2) / (I - I L )

[0050] That is, the calculated virtual resistance R' is the internal impedance at the time of an increase (deterioration) in ion diffusion in the internal state of the battery cell, and is a value estimated from the margin of the voltage drop amount at the time when a prescribed current I L is flowed for a prescribed time (refer to Figure 3 ). The first output allowable power calculation section 308 and the calculated virtual resistance R' are passed to the first output allowable power calculation section 308.

[0051] The first output allowable power calculation section 308 calculates the first output allowable power Wl based on the calculated virtual resistance R'. The first output allowable power calculation section 308, for example, contains a map table for calculating the first output allowable power Wl. That is, the first output allowable power calculation section 308 calculates the first output allowable power Wl corresponding to the calculated virtual resistance R' by setting the virtual resistance R' as input. The first output allowable power calculation section 308 can also be configured to correct the resistance R according to the measured temperature. The first output allowable power calculation section 308 passes the first output allowable power Wl to the output allowable power decision section 310.

[0052] The second output allowable power calculation section 309 calculates the resistance R of the battery cell based on the current I acquired via the measurement value acquisition section 301, and calculates the second output allowable power W2 based on the calculated resistance R. The second output allowable power calculation section 309, for example, contains a map table for calculating the second output allowable power W2. That is, the second output allowable power calculation section 309 calculates the second output allowable power W2 corresponding to the calculated resistance R by setting the resistance R as input. The second output allowable power calculation section 309 can also be configured to correct the resistance R according to the measured temperature. The second output allowable power calculation section 309 passes the second output allowable power W2 to the output allowable power decision section 310. Furthermore, the second output allowable power calculation section 309 is a structure that can be omitted.

[0053] The output allowable power decision section 310 decides the output allowable power W based on the result of comparison between the first output allowable power Wl and the second output allowable power W2. That is, the output allowable power decision section 310 compares the first output allowable power Wl and the second output allowable power W2, and decides the smaller one of the first output allowable power Wl and the second output allowable power W2 as the output allowable power W. The output allowable power decision section 310 controls the power supplied from the battery pack 10 not to exceed the output allowable power W. Thus, the voltage drop AV2 at the time when the prescribed current I L (for example, the maximum current I MAX ) is prevented from being exceeded, and thus the battery pack 10 can be protected and the progress of deterioration can be suppressed. Further, in the case where the second output allowable power calculation section 309 is omitted, the first output allowable power Wl calculated by the first output allowable power calculation section 308 becomes the output allowable power W.

[0054] Figure 5 is a flowchart illustrating an example of a process for deciding the output allowable power performed by the control device according to the embodiment of the present application. The process is realized by the control device 30 executing a prescribed battery control program under the control of a processor in cooperation with prescribed hardware resources. The control device 30 acts by the process to decide the output allowable power W, for example, at every 100 ms.

[0055] As illustrated 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 (the closed-circuit voltage CCV) of the battery cell from the voltage sensor 12a, and acquires the current current I from the current sensor 12b. In addition, the measurement value acquisition section 301 can acquire the current temperature T of the battery from the temperature sensor 12c.

[0056] 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.

[0057] Next, the control device 30 calculates the first voltage drop AVl using the first voltage drop calculation model based on the current I and the open-circuit voltage OCV (S503). In this case, the control device 30 calculates the current first voltage drop AVl (n) using the first voltage drop AVl (n-1) calculated before one unit time (100 ms in this example). Next, the control device 30 calculates the actual discharge voltage VI based on the calculated open-circuit voltage OCV and the current first voltage drop AVl (S504).

[0058] Next, the control device 30 sets the calculated actual discharge voltage VI as an initial value, and calculates a second voltage drop AV2 in a case where a prescribed current I L (such as a maximum current) is assumed to flow in the battery control system 1 for a prescribed time (S505). The prescribed time is, for example, 2 seconds. Next, the control device 30 calculates a virtual discharge voltage V2 based on the calculated open circuit voltage OCV, the first voltage drop AVI, and the second voltage drop AV2 (S506).

[0059] Next, the control device 30 calculates a virtual resistance R' based on the calculated open circuit voltage OCV, the virtual discharge voltage V2, the current I, and the prescribed current I L (S507). That is, the control device 30 estimates the estimated virtual resistance R' from a margin of the voltage drop when the prescribed current I L is assumed to flow for the prescribed time.

[0060] Next, the control device 30 calculates a first output allowable electric power Wl based on the calculated virtual resistance R', using a prescribed mapping table (S508). The control device 30 can also be configured to correct the resistance R' according to the measured temperature.

[0061] In addition, the control device 30 calculates a second output allowable electric power W2 based on the resistance R of the battery, which is calculated based on the current I, using a prescribed mapping table (S509).

[0062] Next, the control device 30 determines whether the first output allowable electric power Wl calculated as described above is equal to or greater than the second output allowable electric power W2 (S510). The control device 30 determines the first output allowable electric power Wl as the output allowable electric power W in a case where the first output allowable electric power Wl is determined to be less than the second output allowable electric power W2 (NO of S510). That is, the output allowable electric power W is the output allowable electric power based on the virtual resistance R' calculated when the prescribed current I L is assumed to flow for the prescribed time. On the other hand, the control device 30 determines the second output allowable electric power W2 as the output allowable electric power W in a case where the first output allowable electric power Wl is determined to be equal to or greater than the second output allowable electric power W2 (YES of S510). The control device 30 controls the electric power supplied from the battery pack 10 not to exceed the output allowable electric power W.

[0063] As described above, according to the present embodiment, the second voltage drop amount AV2 at the time when a current larger than the current I is assumed to flow in the battery control system 1 at a prescribed time is predicted, and thus a more accurate output allowable power W can be determined based on the predicted second voltage drop amount AV2. In particular, according to the present embodiment, the second voltage drop amount AV2 is predicted using a prescribed current I L (maximum current) that is sufficiently large on the specification, and thus the worst condition at the time of vehicle running can be assumed, and thus the optimal output allowable power W can be determined in any situation.

[0064] In addition, according to the present embodiment, by using the current actually measured and acquired, the second voltage drop amount AV2 at the time when a large current is assumed to flow can be predicted in accordance with the state of the current battery. In this case, the current first voltage drop amount AVI(n) is used instead of the previous second voltage drop amount AV2(n-1) when the second voltage drop amount AV2 is calculated, and thus the state of the current battery is taken into consideration, and thus a more accurate second voltage drop amount AV2 can be calculated.

[0065] The above-described embodiments are examples for describing the present application, and are not intended to limit the present application to only these embodiments. The present application can be implemented in various ways without departing from the gist thereof.

[0066] For example, in the method disclosed in the present specification, steps, actions, or functions can be implemented in parallel or in different orders as long as no contradiction is caused in the results. The described steps, actions, and functions are provided as examples, and several of the steps, actions, and functions can be omitted within a range not departing from the gist of the application, and in addition, they can be combined with each other to become one step, action, and function, and in addition, other steps, actions, or functions can be added.

[0067] In addition, various embodiments are disclosed in the present specification, and a specific feature (technical matter) in one embodiment can be appropriately modified and added to or replaced with a specific feature in another embodiment, and such a manner is also included in the gist of the present application.

[0068] Explanation of Reference Numerals

[0069] 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 section; 302: open circuit voltage calculation section (OCV calculation section); 303: first voltage drop amount calculation section; 304: actual discharge voltage calculation section; 305: second voltage drop amount calculation section; 306: virtual discharge voltage calculation section; 307: resistance value calculation section; 308: first output allowable power calculation section; 309: second output allowable power calculation section; 310: output allowable power decision section.

Claims

1. A control device that is a control device in a battery control system, the control device comprising: a current measurement unit that measures a current value of a current output from a battery cell that constitutes a 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, wherein the open circuit voltage is obtained based on the measured current value and the 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, assuming that a prescribed current has flowed for a prescribed 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.

2. The control device according to claim 1, wherein the prescribed current is a maximum current that the battery control system allows in specifications.

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

4. The control device according to claim 3, wherein the second voltage drop amount calculation unit calculates a current second voltage drop amount based on the current first voltage drop amount, not the second voltage drop amount calculated in the unit time.

5. The control device according to claim 3, wherein the prescribed time is a time longer than the unit time.

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

7. The control device according to claim 1, further comprising: a second voltage drop amount calculation unit that calculates a second output allowable power based on the current and the open circuit voltage; and an output allowable power decision unit that decides an output allowable power of the battery control system based on the calculated first output allowable power and the second output allowable power.

8. The control device according to claim 7, wherein the output allowable power decision unit compares the first output allowable power and the second output allowable power, and decides a value of the smaller one as the output allowable power.

9. A method of deciding an output allowable power of a battery, comprising: measuring a current value of a current output from a battery cell that constitutes 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, wherein the open circuit voltage is obtained based on the measured current value and the 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, which is assumed to flow a prescribed current for a prescribed 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 deciding an output allowable power based on the calculated virtual resistance value.

Images