Battery apparatus and method of calculating available power

Abstract

A processor of a battery device receives measurement information including the cell voltage and current of the battery, calculates the resistance of the battery, and, when a predetermined condition is satisfied, applies a gain determined by the cell voltage to at least one of the current or the resistance, and after applying the gain, estimates the maximum available current of the battery based on the measurement information and the resistance, and calculates the available power of the battery based on the maximum available current.

Description

Technology Field

[0001] The present invention relates to a battery device and a method for calculating available power. Background Technology

[0002] Electric or hybrid vehicles are vehicles that generate power by driving a motor primarily using a battery as a power source, and active research is being conducted on them as an alternative capable of solving the pollution and energy problems associated with internal combustion engine vehicles. In addition, rechargeable batteries are being used in various external devices in addition to electric vehicles.

[0003] As batteries are used in various external devices, logic is required to utilize maximum power while preventing cell undervoltage within the battery's usable range. Currently, derating logic, which reduces battery power to prevent cell undervoltage, is used. However, due to the inherent characteristics of batteries, cell voltage drops non-linearly and rapidly at low temperatures, making it difficult to prevent cell undervoltage issues by estimating the voltage. The problem to be solved

[0004] Some embodiments of the present invention may provide a battery device capable of preventing cell low voltage and a method for calculating available power. means of solving the problem

[0005] According to one embodiment of the present invention, a method for calculating the available power of a battery may be provided. The method for calculating the available power may include the steps of receiving measurement information including a cell voltage of the battery and a current of the battery; calculating the resistance of the battery; reflecting a gain determined by the cell voltage to at least one of the current or the resistance when a predetermined condition is satisfied; estimating the maximum available current of the battery based on the measurement information and the resistance after reflecting the gain; and calculating the available power of the battery based on the maximum available current.

[0006] In some embodiments, the predetermined condition may include a condition in which the temperature of the battery is below a predetermined temperature.

[0007] In some embodiments, the step of reflecting the gain to at least one of the current or the resistance may include the step of multiplying the resistance by a resistance gain inversely proportional to the cell voltage.

[0008] In some embodiments, the step of reflecting the gain to at least one of the current or the resistance may include the step of multiplying the current by a current gain proportional to the cell voltage.

[0009] In some embodiments, the available power calculation method may further include the step of estimating the cell voltage after a requested period based on the cell voltage and the current. The step of estimating the maximum available current may include the step of estimating the maximum available current based on the cell voltage after the requested period, the target voltage, the current after reflecting the gain, and the resistance.

[0010] In some embodiments, the step of calculating the available power may include the step of estimating the final voltage based on the cell voltage after the requested period, the maximum available current, the current, and the resistance, and the step of calculating the available power based on the maximum available current and the final voltage.

[0011] According to another embodiment of the present invention, a battery device comprising a battery cell and a processor may be provided. The processor estimates a maximum available current of the battery based on measurement information including a cell voltage of the battery and a current of the battery and a resistance of the battery, and when estimating the maximum available current, it may adjust at least one of the current or the resistance according to the cell voltage.

[0012] In some embodiments, the processor can adjust at least one of the current or the resistance by multiplying the gain determined by the cell voltage by at least one of the current or the resistance.

[0013] In some embodiments, the gain may include a resistance gain inversely proportional to the cell voltage. The processor may adjust the resistance by multiplying the resistance gain by the resistance.

[0014] In some embodiments, the gain may include a current gain proportional to the cell voltage. The processor may adjust the current by multiplying the current gain by the current.

[0015] In some embodiments, the battery device may further include a memory that stores a correspondence relationship between the cell voltage and the gain. The processor may determine the gain corresponding to the cell voltage by referring to the memory.

[0016] In some embodiments, the processor may estimate the cell voltage after a requested period based on the cell voltage and the current, and estimate the maximum available current based on the current, the cell voltage after the requested period, the target voltage, and the resistance.

[0017] In some embodiments, the processor may estimate a final voltage based on the cell voltage after the requested period, the maximum available current, the current, and the resistance, and estimate available power based on the maximum available current and the final voltage.

[0018] In some embodiments, when estimating the maximum available current, the processor may multiply the current by a current gain proportional to the cell voltage and multiply the resistance by a resistance gain inversely proportional to the cell voltage.

[0019] According to another embodiment of the present invention, a recording medium may be provided having a program executed by a processor of a battery device. The program may enable the processor to perform the steps of receiving measurement information including a cell voltage of the battery and a current of the battery; calculating the resistance of the battery; applying a gain determined by the cell voltage to at least one of the current or the resistance when a predetermined condition is satisfied; estimating the maximum available current of the battery based on the measurement information and the resistance after applying the gain; and calculating the available power of the battery based on the maximum available current. Effects of the invention

[0020] According to some embodiments, by adjusting the resistance gain or current gain according to the cell voltage, the maximum available current can be reduced and cell undervoltage can be prevented. Brief explanation of the drawing

[0021] FIG. 1 is a drawing showing a battery device according to one embodiment of the present invention. FIG. 2 is a flowchart illustrating an example of a method for estimating available power according to one embodiment of the present invention. FIG. 3 is a flowchart illustrating an example of a method for estimating available power according to another embodiment of the present invention. FIG. 4 is a diagram showing an example of an equivalent circuit model of a battery according to one embodiment of the present invention. Specific details for implementing the invention

[0022] Embodiments of the present invention are described below with reference to the attached drawings so that those skilled in the art can easily implement them. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein. Furthermore, in order to clearly explain the present invention in the drawings, parts unrelated to the explanation have been omitted, and similar parts throughout the specification are denoted by similar reference numerals.

[0023] When it is stated that a component is "connected" to another component, it should be understood that it may be directly connected to that other component, or that there may be other components in between. On the other hand, when it is stated that a component is "directly connected" to another component, it should be understood that there are no other components in between.

[0024] Expressions written in the singular in the description below may be interpreted as singular or plural unless explicit expressions such as "one" or "singular" are used.

[0025] In the flowchart described with reference to the drawings, the order of operations may be changed, multiple operations may be merged or some operations may be divided, and specific operations may not be performed.

[0026] FIG. 1 is a drawing showing a battery device according to one embodiment of the present invention.

[0027] Referring to FIG. 1, the battery device (100) has a structure that can be electrically connected to an external device. When the external device is a load, the battery device (100) operates as a power source that supplies power to the load and discharges. When the external device is a charger, the battery device (100) receives external power through the charger and is charged. The external device operating as a load may be, for example, an electronic device, a means of transportation, or an energy storage system (ESS), and the means of transportation may be, for example, an electric vehicle, a hybrid vehicle, or a smart mobility vehicle.

[0028] The battery device (100) includes a battery (110), a voltage measuring circuit (120), a temperature sensor (130), a current sensor (140), and a processor (150).

[0029] The battery (110) is a rechargeable secondary battery. The battery (110) may be a lithium battery, such as a lithium-ion battery or a lithium-ion polymer battery, or a nickel battery, such as a nickel-cadmium (NiCd) battery or a nickel-hydrogen (NiMH) battery. In some embodiments, the battery (110) may be a single battery cell, an assembly of multiple battery cells or a battery module in which multiple assemblies are connected in series or parallel, a battery pack in which multiple battery modules are connected in series or parallel, or a system in which multiple battery packs are connected in series or parallel.

[0030] The voltage measuring circuit (120) measures the voltage of the battery (110). In some embodiments, the voltage measuring circuit (120) can measure the voltage of each battery cell.

[0031] The temperature sensor (130) measures the temperature of the battery (110). In some embodiments, the temperature sensor (130) may measure the temperature at a predetermined location of the battery (110). In some embodiments, a plurality of temperature sensors (130) may be provided to measure the temperature at a plurality of locations in the battery (110).

[0032] The current sensor (140) is connected to the positive output terminal or negative output terminal of the battery (110) and measures the current of the battery (110), i.e., the charging current or the discharging current.

[0033] The processor (150) estimates the available power of the battery (110) based on the voltage of the battery (110) measured by the voltage measurement circuit (120), the temperature of the battery (110) measured by the temperature sensor (130), or the current of the battery (110) measured by the current sensor (140). In some embodiments, the battery device (100) may further include a memory (160) for storing data necessary for estimating the available power in the processor (150).

[0034] In some embodiments, the processor (150) may form a battery management system. In some embodiments, the battery management system may further include at least one of a voltage measurement circuit (120), a temperature sensor (130), a current sensor (140), or a memory (160).

[0035] FIG. 2 is a flowchart illustrating an example of a method for estimating available power according to one embodiment of the present invention.

[0036] Referring to FIG. 2, a processor (e.g., 150 in FIG. 1) receives measurement information of a battery (e.g., 110 in FIG. 1) (S210). The measurement information of the battery (110) is information of the battery (110) measured at a current point in time and may include the current of the battery (110) and the voltage of the battery (110). In some embodiments, the current of the battery (110) may be the charging or discharging current of the battery (110) measured by a current sensor (e.g., 140 in FIG. 1). In some embodiments, the voltage of the battery (110) may be the voltage of a battery cell (hereinafter referred to as "cell voltage") measured by a voltage measurement circuit (e.g., 120 in FIG. 1). In some embodiments, the cell voltage may be the average value of the voltages of a plurality of battery cells (average cell voltage). In some embodiments, the measurement information of the battery (110) may further include the temperature of the battery (110). In some embodiments, the temperature of the battery (110) may be the temperature measured by a temperature sensor (e.g., 130 in FIG. 1).

[0037] Next, the processor (150) calculates the resistance of the battery (110) based on the measurement information of the battery (110) (S220). Additionally, the processor (150) adjusts the resistance of the battery (110) based on the cell voltage (S230). In some embodiments, the processor (150) may adjust the resistance by multiplying the resistance of the battery (110) by a resistance gain based on the cell voltage. In this case, the resistance gain may be inversely proportional to the cell voltage. In some embodiments, the processor (150) may set the resistance gain when the measured cell voltage is a first cell voltage higher than the resistance gain when the measured cell voltage is a second cell voltage higher than the first cell voltage. In some embodiments, the processor (150) may store a correspondence relationship between the cell voltage and the resistance gain in advance and retrieve the resistance gain corresponding to the measured cell voltage from the correspondence relationship. In some embodiments, the memory of the battery management system (e.g., 160 in FIG. 1) may store the correspondence relationship in the form of, for example, a lookup table. The correspondence relationship can be given, for example, as shown in Table 1.

[0038] Cell voltage Resistance gain 2.5 8 2.7 6 2.8 5 2.9 4 3.0 3 3.1 2 3.2 1.5 3.3 1.1 3.4 1

[0039] Next, the processor (150) estimates the maximum available current of the battery (110) based on the measurement information of the battery (110) and the adjusted resistance (e.g., a resistance with a resistance gain) (S240). The processor (150) estimates the final voltage of the battery (110) based on the maximum available current and the adjusted resistance (S250). The processor (150) calculates the available power based on the maximum available current and the final voltage (S260). In some embodiments, if the available power calculated in S260 is the available power of the battery cell, the processor (150) can calculate the final available power by multiplying the available power by the number of battery cells included in the battery pack.

[0040] In some embodiments, the processor (150) can adjust the resistance of the battery (110) only when the measurement information of the battery (110) satisfies a predetermined condition (S270) (S230). In some embodiments, the processor (150) can multiply the resistance of the battery (110) by a resistance gain only when the measurement information of the battery (110) satisfies a predetermined condition (S270) (S230). When the measurement information of the battery (110) does not satisfies a predetermined condition, the processor (150) can perform operations S240 to S260 with the resistance of the battery (110) without multiplying the resistance gain. In some embodiments, when the measurement information of the battery (110) does not satisfies a predetermined condition, the processor (150) may not multiply the resistance gain by multiplying the resistance of the battery (110) by a resistance gain having a value of 1. In some embodiments, the predetermined condition may include a condition in which the temperature of the battery (110) currently measured is below a predetermined temperature. In some embodiments, the predetermined temperature may be 0°C.

[0041] According to the embodiments described above, the maximum available current can be reduced by changing the gain according to the cell voltage. Accordingly, cell undervoltage can be prevented. In some embodiments, since the cell voltage drops sharply at low temperatures below a predetermined temperature, cell undervoltage can be prevented by reflecting the current gain or resistance gain at low temperatures.

[0042] FIG. 3 is a flowchart illustrating an example of a method for estimating available power according to another embodiment of the present invention, and FIG. 4 is a diagram illustrating an example of an equivalent circuit model of a battery according to one embodiment of the present invention.

[0043] Referring to FIG. 3, a processor (e.g., 150 in FIG. 1) receives measurement information of a battery (e.g., 110 in FIG. 1) (S310). The measurement information of the battery (110) is information of the battery (110) measured at a current point in time and may include the current of the battery (110) and the voltage of the battery (110). In some embodiments, the current of the battery (110) may be the charging or discharging current of the battery (110) measured by a current sensor (e.g., 140 in FIG. 1). In some embodiments, the voltage of the battery (110) may be the voltage of a battery cell (hereinafter referred to as "cell voltage") measured by a voltage measurement circuit (e.g., 120 in FIG. 1). In some embodiments, the cell voltage may be the average value of the voltages of a plurality of battery cells (average cell voltage). In some embodiments, the measurement information of the battery (110) may further include the temperature of the battery (110). In some embodiments, the temperature of the battery (110) may be the temperature measured by a temperature sensor (e.g., 130 in FIG. 1).

[0044] Next, the processor (150) predicts the voltage of the battery (110) after the requested time (S320). In some embodiments, the processor (150) predicts the voltage (V) of the battery (110) based on an equivalent circuit model of the battery (110). est ) can be predicted. For example, the processor (150) can predict the voltage (V) of the battery (110) after the requested time. est ) can be predicted as in Equation 1. In some embodiments, the processor (150) predicts the voltage (V) of the battery (110) under the assumption that the current remains at the current current (current measured at the present time) even after the requested time. est ) can be predicted.

[0045]

[0046] In mathematical equation 1, V now is the voltage of the battery (110) measured at the current point in time, and T reqis the requested time, τ is the time constant of the RC parallel circuit in the battery equivalent circuit model, R1 is the resistance value of the resistor in the RC parallel circuit (431 in Fig. 4), and I now is the current (current current) of the battery (110) measured at the present time, and V pol This is the polarization voltage of the battery (110).

[0047] Referring to FIG. 4, the equivalent circuit model of the battery includes an open-circuit voltage source (410), a series resistor (420), and an RC parallel circuit.

[0048] The open-circuit voltage source (410) simulates the open-circuit voltage, which is the voltage between the positive and negative electrodes of an electrochemically stabilized battery. The open-circuit voltage can be determined by the state of charge (SOC) of the battery (110) and may have a non-linear functional relationship with the SOC. The series resistor (420) simulates the internal resistance of the battery (110), which represents the voltage drop inside the battery (110) caused by the current flowing through the battery (110), and represents the instantaneous change in the battery terminal voltage caused by the current flowing through the battery (110). The RC parallel circuit simulates the polarization voltage reflected in the battery terminal voltage, i.e., the transient change of over-potential, and includes a resistor (431) and a capacitor (432) connected in parallel. In this equivalent circuit model, the terminal voltage (V) of the battery t ) may correspond to the voltage of the battery (110).

[0049] In addition, the processor (150) requests a period (T req Resistance (R) of the battery (110) after ) net ) calculates (S330). In some embodiments, a certain period (T) from an external device (e.g., a vehicle) req Available power during ) can be requested. In some embodiments, the processor (150) may request the resistance (R) of the battery (110) based on an equivalent circuit model of the battery (110).net ) can be calculated. For example, the processor (150) can calculate the requested period (T req Resistance (R) of the battery (110) after ) net ) can be calculated as in mathematical formula 2.

[0050]

[0051] In mathematical equation 2, R0 is the resistance value of the series resistor (420) in the battery equivalent circuit model.

[0052] Next, the processor (150) adjusts at least one of the resistance or current of the battery (110) based on the cell voltage (S340). In some embodiments, the processor (150) may adjust the resistance by multiplying the resistance of the battery (110) by a resistance gain based on the cell voltage. In this case, the resistance gain may be inversely proportional to the cell voltage. In some embodiments, the processor (150) may set the resistance gain higher when the measured cell voltage is a first cell voltage than the resistance gain when the measured cell voltage is a second cell voltage higher than the first cell voltage. In some embodiments, the processor (150) may adjust the current current by multiplying the current current of the battery (110) by a current gain based on the cell voltage. In this case, the current gain may be proportional to the cell voltage. In some embodiments, the processor (150) may set the current gain lower when the measured cell voltage is a first cell voltage than the current gain when the measured cell voltage is a second cell voltage higher than the first cell voltage. In some embodiments, the processor (150) may store in advance a correspondence between a cell voltage and a resistance gain and / or a correspondence between a cell voltage and a current gain, and may retrieve a resistance gain and / or current gain corresponding to a measured cell voltage from the correspondence. In some embodiments, a memory of the battery management system (e.g., 160 in FIG. 1) may store the correspondence in the form of, for example, a lookup table. The correspondence may be given as, for example, Table 2.

[0053] Cell voltage Current gain Resistance gain 2.5 0.7 8 2.7 0.7 6 2.8 0.7 5 2.9 0.75 4 3.0 0.8 3 3.1 0.9 2 3.2 1 1.5 3.3 1 1.1 3.4 1 1

[0054] Next, the processor (150) determines the predicted voltage (V) of the battery (110). est ), current current (I now ), resistance (R net ) and target voltage (V target The maximum available current of the battery (110) is estimated based on (S350). In some embodiments, the processor (150) may calculate the maximum available current using the current current or resistance adjusted in S340. In some embodiments, the processor (150) may calculate the maximum available current under the assumption that the current current is maintained for a requested period. For example, the processor (150) calculates the maximum available current (I max ) can be calculated as in mathematical formula 3.

[0055]

[0056] In mathematical equation 3, I gain is the current gain, and R gain is the resistance gain.

[0057] Next, the processor (150) determines the maximum available current (I) at the current current. max The final voltage (V) when additional current is applied up to ) final ) estimates (S360). For example, the processor (150) estimates the maximum voltage (V final ) can be calculated as in mathematical formula 4.

[0058]

[0059] The processor (150) has available power (P) based on the maximum available current and final voltage. raw ) calculates (S370). For example, the processor (150) calculates available power (P raw ) can be calculated as in mathematical formula 5.

[0060] In some embodiments, if the available power calculated in S370 is the available power of the battery cell, the processor (150) can calculate the final available power by multiplying the available power by the number of battery cells included in the battery pack.

[0061]

[0062] In some embodiments, the processor (150) can adjust at least one of the current current or resistance of the battery (110) only when the measurement information of the battery (110) satisfies a predetermined condition (S380) (S340). In some embodiments, the processor (150) can multiply the resistance of the battery (110) by a resistance gain or multiply the current current by a current gain only when the measurement information of the battery (110) satisfies a predetermined condition (S380) (S340). When the measurement information of the battery (110) does not satisfies a predetermined condition, the processor (150) can perform the operations of S350 to S370 with the resistance of the battery (110) without multiplying by a resistance gain and the current current of the battery (110) without multiplying by a current gain. In some embodiments, when the measurement information of the battery (110) does not satisfy a predetermined condition, the processor (150) may not multiply the resistance gain and the current gain by multiplying the resistance of the battery (110) by a resistance gain having a value of 1 and the current gain having a value of 1 by multiplying the current current by a current gain having a value of 1. In some embodiments, the predetermined condition may include a condition in which the temperature of the currently measured battery (110) is below a predetermined temperature. In some embodiments, the predetermined temperature may be 0°C.

[0063] According to the embodiments described above, the maximum available current can be reduced by increasing the current gain and decreasing the resistance gain as the cell voltage decreases. Accordingly, cell undervoltage can be prevented. In some embodiments, since the cell voltage drops sharply at low temperatures below a predetermined temperature, cell undervoltage can be prevented by reflecting the current gain or resistance gain at low temperatures.

[0064] In some embodiments, a processor (e.g., 150 in FIG. 1) may perform operations on a program for executing the available power estimation method described above. The program for executing the available power estimation method may be loaded into memory. This memory may be the same memory as the memory storing the table (e.g., 160 in FIG. 1) or a separate memory. When the program is loaded into memory, it may include instructions that cause the processor (150) to perform the available power estimation method. That is, the processor may perform operations for the available power estimation method by executing the instructions of the program.

[0065] Although embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the present invention as defined in the following claims also fall within the scope of the present invention.

Claims

Claim 1 A method for calculating available power of a battery, comprising: receiving measurement information including a cell voltage of the battery and a current of the battery; calculating the resistance of the battery; when a predetermined condition is satisfied, applying a gain determined by the cell voltage to at least one of the current or the resistance; after applying the gain, estimating the maximum available current of the battery based on the measurement information and the resistance; and calculating the available power of the battery based on the maximum available current, wherein the step of applying the gain to at least one of the current or the resistance includes the step of multiplying the resistance by a resistance gain inversely proportional to the cell voltage. Claim 2 A method for calculating available power according to claim 1, wherein the predetermined condition includes a condition in which the temperature of the battery is below a predetermined temperature. Claim 3 delete Claim 4 A method for calculating available power of a battery, comprising: receiving measurement information including a cell voltage of the battery and a current of the battery; calculating the resistance of the battery; applying a gain determined by the cell voltage to at least one of the current or the resistance when a predetermined condition is satisfied; estimating a maximum available current of the battery based on the measurement information and the resistance after applying the gain; and calculating the available power of the battery based on the maximum available current, wherein the step of applying the gain to at least one of the current or the resistance includes the step of multiplying the current by a current gain proportional to the cell voltage. Claim 5 A method for calculating available power according to claim 1 or 4, further comprising the step of estimating the cell voltage after a requested period based on the cell voltage and the current, wherein the step of estimating the maximum available current comprises the step of estimating the maximum available current based on the resistance and the current after reflecting the cell voltage after the requested period, the target voltage, and the gain. Claim 6 In claim 5, the step of calculating the available power comprises a method for calculating available power including a step of estimating a final voltage based on the cell voltage after the requested period, the maximum available current, the current, and the resistance, and a step of calculating the available power based on the maximum available current and the final voltage. Claim 7 A battery device comprising a battery including a battery cell, and a processor that estimates a maximum available current of the battery based on measurement information including a cell voltage of the battery and a current of the battery and a resistance of the battery, and adjusts at least one of the current or the resistance according to the cell voltage when estimating the maximum available current, wherein the processor adjusts at least one of the current or the resistance by multiplying a gain determined by the cell voltage by at least one of the current or the resistance. Claim 8 delete Claim 9 In claim 7, the gain includes a resistance gain inversely proportional to the cell voltage, and the processor adjusts the resistance by multiplying the resistance gain by the resistance, a battery device. Claim 10 A battery device according to claim 7, wherein the gain includes a current gain proportional to the cell voltage, and the processor adjusts the current by multiplying the current gain by the current. Claim 11 A battery device according to claim 7, further comprising a memory for storing a correspondence relationship between the cell voltage and the gain, wherein the processor determines the gain corresponding to the cell voltage by referring to the memory. Claim 12 In claim 7, the battery device, wherein the processor estimates the cell voltage after a requested period based on the cell voltage and the current, and estimates the maximum available current based on the current, the cell voltage after the requested period, the target voltage, and the resistance. Claim 13 In claim 12, the battery device, wherein the processor estimates a final voltage based on the cell voltage after the requested period, the maximum available current, the current, and the resistance, and estimates available power based on the maximum available current and the final voltage. Claim 14 A battery device according to claim 12, wherein the processor, when estimating the maximum available current, multiplies the current by a current gain proportional to the cell voltage and multiplies the resistance by a resistance gain inversely proportional to the cell voltage. Claim 15 A recording medium having a recording medium on which a program executed by a processor of a battery device is recorded, wherein the program enables the processor to execute the steps of receiving measurement information including a cell voltage of the battery and a current of the battery, calculating the resistance of the battery, applying a gain determined by the cell voltage to at least one of the current or the resistance when a predetermined condition is satisfied, estimating the maximum available current of the battery based on the measurement information and the resistance after applying the gain, and calculating the available power of the battery based on the maximum available current, wherein the step of applying the gain to at least one of the current or the resistance includes the step of multiplying the resistance by a first resistance gain inversely proportional to the cell voltage or a second resistance gain proportional to the cell voltage.

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