KR20230056415A - Battery apparatus and method of calculating available power - Google Patents

Abstract

The processor of the battery device receives measurement information including a cell voltage of the battery and a current of the battery, calculates resistance of the battery, and, when a predetermined condition is met, sets a gain determined by the cell voltage to at least one of current or resistance. After reflecting one and reflecting the gain, the maximum available current of the battery is estimated based on the measurement information and the resistance, and the available power of the battery is calculated based on the maximum available current.

Description

Battery device and available power calculation method {BATTERY APPARATUS AND METHOD OF CALCULATING AVAILABLE POWER}

The present invention relates to a battery device and a method for calculating available power.

An electric vehicle or hybrid vehicle is a vehicle that obtains power by driving a motor using a battery as a power source, and research is being actively conducted in that it is an alternative to solving the pollution and energy problems of internal combustion vehicles. In addition, rechargeable batteries are used in various external devices other than electric vehicles.

As batteries are used in various external devices, a logic that uses maximum power while preventing cell undervoltage within a usable range of the battery is required. Currently, a derating logic that reduces battery power is used to prevent cell undervoltage. However, due to the nature of the battery, since the cell voltage rapidly drops nonlinearly at low temperatures, it is difficult to prevent the cell low voltage problem by estimating the cell voltage.

Certain embodiments of the present invention may provide a battery device capable of preventing cell low voltage and a method for calculating available power.

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

In some embodiments, the predetermined condition may include a condition in which the temperature of the battery is equal to or less than a predetermined temperature.

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

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

In some embodiments, the method of calculating available power may further include estimating a cell voltage after a requested period based on the cell voltage and the current. The estimating of the maximum available current may include 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.

In some embodiments, calculating the available power includes estimating a final voltage based on the cell voltage after the requested period, the maximum available current, the current and the resistance, and the maximum available current and the final voltage. Calculating the available power based on the voltage may be included.

According to another embodiment of the present invention, a battery device including a battery including a battery cell and a processor may be provided. The processor estimates the maximum available current of the battery based on measurement information including the cell voltage and current of the battery and the resistance of the battery, and when estimating the maximum available current, the processor determines the maximum available current according to the cell voltage. At least one of the current or the resistance may be adjusted.

In some embodiments, the processor may adjust at least one of the current or the resistance by multiplying at least one of the current or the resistance by a gain determined by the cell voltage.

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

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 by the current gain.

In some embodiments, the battery device may further include a memory storing a correspondence between the cell voltage and the gain. The processor may determine the gain corresponding to the cell voltage by referring to the memory.

In some embodiments, the processor estimates a cell voltage after a requested period based on the cell voltage and the current, and the maximum cell voltage based on the current, the cell voltage after the requested period, a target voltage, and the resistance. The available current can be estimated.

In some embodiments, the processor estimates a final voltage based on the cell voltage after the requested period of time, the maximum available current, the current and the resistance, and determines an available power based on the maximum available current and the final voltage. can be estimated

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.

According to another embodiment of the present invention, a recording medium on which a program executed by a processor of a battery device is recorded may be provided. The program may include, by the processor, receiving measurement information including a cell voltage of the battery and a current of the battery, calculating a resistance of the battery, and determining the cell voltage when a predetermined condition is satisfied. reflecting the gain to at least one of the current or the resistance, estimating the maximum available current of the battery based on the measurement information and the resistance after reflecting the gain, and based on the maximum available current The step of calculating the available power of the battery may be executed.

According to some embodiments, a maximum available current may be reduced and cell undervoltage may be prevented by adjusting a resistance gain or a current gain according to a cell voltage.

1 is a diagram illustrating a battery device according to an embodiment of the present invention.
2 is a flowchart illustrating an example of a method for estimating available power according to an embodiment of the present invention.
3 is a flowchart illustrating an example of a method for estimating available power according to another embodiment of the present invention.
4 is a diagram illustrating an example of an equivalent circuit model of a battery according to an embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings, embodiments of the present invention will be described in detail so that those skilled in the art can easily carry out the present invention. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein. And in order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted, and similar reference numerals are attached to similar parts throughout the specification.

It should be understood that when an element is referred to as being “connected” to another element, it may be directly connected to the other element, but other elements may exist in the middle. On the other hand, when an element is referred to as being “directly connected” to another element, it should be understood that no intervening elements exist.

Expressions written in the singular in the following description may be interpreted in the singular or plural unless explicit expressions such as “one” or “single” are used.

In the flowchart described with reference to the drawings, the order of operations may be changed, several operations may be merged, a certain operation may be divided, and a specific operation may not be performed.

1 is a diagram illustrating a battery device according to an embodiment of the present invention.

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 supply supplying power to the load and is discharged. When the external device is a charger, the battery device 100 is charged by receiving external power through the charger. The external device operating as a load may be, for example, an electronic device, a transportation means, or an energy storage system (ESS), and the transportation means may be, for example, an electric vehicle, a hybrid vehicle, or a smart mobility vehicle. may be a vehicle.

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 .

The battery 110 is a rechargeable secondary battery. The battery 110 may be, for example, 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, battery 110 may be a single battery cell, an assembly of multiple battery cells or a battery module of multiple battery cells connected in series or parallel, a battery pack having multiple battery modules connected in series or parallel, or a plurality of batteries. The packs can be series or parallel connected systems.

The voltage measuring circuit 120 measures the voltage of the battery 110 . In some embodiments, the voltage measurement circuit 120 may measure the voltage of each battery cell.

The temperature sensor 130 measures the temperature of the battery 110 . In some embodiments, the temperature sensor 130 may measure the temperature of a predetermined location of the battery 110 . In some embodiments, a plurality of temperature sensors 130 may be provided to measure the temperature of a plurality of locations on the battery 110 .

The current sensor 140 is connected to the positive output terminal or the negative output terminal of the battery 110 and measures the current of the battery 110, that is, the charging current or the discharging current.

The processor 150 measures the voltage of the battery 110 measured by the voltage measuring 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. The available power of the battery 110 is estimated based on . In some embodiments, the battery device 100 may further include a memory 160 that stores data necessary for estimating available power in the processor 150 .

In some embodiments, processor 150 may form a battery management system. In some embodiments, the battery management system may further include at least one of a voltage measuring circuit 120 , a temperature sensor 130 , a current sensor 140 , and a memory 160 .

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

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

Next, the processor 150 calculates the resistance of the battery 110 based on the measurement information of the battery 110 (S220). Also, 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 the first cell voltage higher than the resistance gain when the measured cell voltage is the second cell voltage higher than the first cell voltage. In some embodiments, the processor 150 may pre-store a correspondence relationship between cell voltages and resistance gains, and may retrieve resistance gains corresponding to the measured cell voltages from the correspondence relationship. In some embodiments, the memory (eg, 160 of FIG. 1 ) of the battery management system may store the corresponding relationship in the form of a lookup table, for example. Correspondence may be given as shown in Table 1, for example.

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 One

Next, the processor 150 estimates the maximum available current of the battery 110 based on the measured information of the battery 110 and the adjusted resistance (eg, resistance to which the resistance gain is reflected) (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 available power based on the maximum available current and final voltage (S260). In some embodiments, when the available power calculated in S260 is the available power of the battery cells, the processor 150 may calculate the final available power by multiplying the available power by the number of battery cells included in the battery pack.

In some embodiments, the processor 150 may adjust the resistance of the battery 110 only when the measurement information of the battery 110 satisfies a predetermined condition (S270). In some embodiments, the processor 150 may 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). When the measurement information of the battery 110 does not satisfy a predetermined condition, the processor 150 may perform operations S240 to S260 with the resistance of the battery 110 not multiplied by the resistance gain. In some embodiments, when the measurement information of the battery 110 does not satisfy a predetermined condition, the processor 150 multiplies the resistance of the battery 110 by a resistance gain having a value of 1 so that the resistance gain is not multiplied. may not be In some embodiments, the predetermined condition may include a condition in which the currently measured temperature of the battery 110 is equal to or less than a predetermined temperature. In some embodiments, the predetermined temperature may be 0°C.

According to the embodiment described above, the maximum available current can be reduced by changing the gain according to the cell voltage. Accordingly, cell low voltage can be prevented. In some embodiments, since cell voltage drops rapidly at a low temperature below a predetermined temperature, cell low voltage may be prevented by reflecting current gain or resistance gain at low temperature.

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 showing an example of an equivalent circuit model of a battery according to an embodiment of the present invention.

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

Next, the processor 150 predicts the voltage of the battery 110 after the requested time (S320). In some embodiments, the processor 150 may predict the voltage V _est of the battery 110 based on the equivalent circuit model of the battery 110 . For example, the processor 150 may predict the voltage V _est of the battery 110 after the requested time as shown in Equation 1. In some embodiments, the processor 150 may predict the voltage V _est of the battery 110 under the assumption that the current remains at the current current (the current measured at the current point in time) after the requested time.

In Equation 1, V _now is the voltage of the battery 110 measured at the present time, T _req is the requested time, τ is the time constant of the RC parallel circuit in the battery equivalent circuit model, and R ₁ is the RC parallel circuit is the resistance value of the resistance (431 in FIG. 4), I _now is the current (current current) of the battery 110 measured at the present time, and V _pol is the polarization voltage of the battery 110.

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.

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 may be determined by a state of charge (SOC) of the battery 110 and may have a non-linear function relationship with SOC. The series resistance 420 simulates the internal resistance of the battery 110 representing the voltage drop inside the battery 110 due to the current flowing through the battery 110, and the instantaneous voltage of the battery terminal due to the current flowing through the battery 110 represents a positive change. The RC parallel circuit simulates the polarization voltage reflected in the battery terminal voltage, that is, the transient change of the over-potential, and includes a resistor 431 and a capacitor 432 connected in parallel. In this equivalent circuit model, the terminal voltage (V _t ) of the battery may correspond to the voltage of the battery 110 .

Also, the processor 150 calculates the resistance (R _net ) of the battery 110 after the requested period (T _req ) (S330). In some embodiments, available power for a certain period of time (T _req ) may be requested from an external device (eg, a vehicle). In some embodiments, the processor 150 may calculate the resistance R _net of the battery 110 based on an equivalent circuit model of the battery 110 . For example, the processor 150 may calculate the resistance R _net of the battery 110 after the requested period T _req as in Equation 2.

In Equation 2, R ₀ is the resistance value of the series resistor 420 in the battery equivalent circuit model.

Next, the processor 150 adjusts at least one of the resistance or the current 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 when the measured cell voltage is the first cell voltage higher than the resistance gain when the measured cell voltage is the second cell voltage higher than the first cell voltage. In some embodiments, the processor 150 may adjust the current current by multiplying the current gain 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 a current gain when the measured cell voltage is the first cell voltage lower than a current gain when the measured cell voltage is a second cell voltage higher than the first cell voltage. In some embodiments, the processor 150 pre-stores a correspondence relationship between a cell voltage and a resistance gain and/or a correspondence relationship between a cell voltage and a current gain, and the resistance gain and/or current gain corresponding to the measured cell voltage. can be retrieved from the corresponding relationship. In some embodiments, the memory (eg, 160 of FIG. 1 ) of the battery management system may store the corresponding relationship in the form of a lookup table, for example. Correspondence may be given as shown in Table 2, for example.

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 One 1.5 3.3 One 1.1 3.4 One One

Next, the processor 150 determines the maximum available current of the battery 110 based on the predicted voltage (V _est ), current current (I _now ), resistance (R _net ), and target voltage (V _target ) of the battery 110 . Estimate (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, processor 150 may calculate the maximum available current assuming that the current current is maintained for the requested period of time. For example, the processor 150 may calculate the maximum available current (I _max ) as in Equation 3.

In Equation 3, I _gain is the current gain and R _gain is the resistance gain.

Next, the processor 150 estimates a final voltage (V _final ) when a current is further applied from the current current to the maximum available current (I _max ) (S360). For example, the processor 150 may calculate the maximum voltage V _final as in Equation 4.

The processor 150 calculates the available power (P _raw ) based on the maximum available current and the final voltage (S370). For example, the processor 150 may calculate the available power P _raw as in Equation 5.

In some embodiments, when the available power calculated in S370 is the available power of the battery cells, the processor 150 may calculate the final available power by multiplying the available power by the number of battery cells included in the battery pack.

In some embodiments, the processor 150 may adjust at least one of current current or resistance of the battery 110 only when measurement information of the battery 110 satisfies a predetermined condition (S380). In some embodiments, the processor 150 may 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 satisfy a predetermined condition, the processor 150 determines the resistance of the battery 110 not multiplied by the resistance gain and the current current of the battery 110 not multiplied by the current gain at S350. The operations of S370 to S370 may be performed. In some embodiments, when the measurement information of the battery 110 does not satisfy a predetermined condition, the processor 150 multiplies the resistance of the battery 110 by a resistance gain having a value of 1 and assigns a value of 1 to the current current. By multiplying the current gain, the resistance gain and the current gain may not be multiplied. In some embodiments, the predetermined condition may include a condition in which the currently measured temperature of the battery 110 is equal to or less than a predetermined temperature. In some embodiments, the predetermined temperature may be 0°C.

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

In some embodiments, the processor (eg, 150 of FIG. 1 ) may perform calculations on a program for executing the method for estimating available power described above. A 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 (eg, 160 in FIG. 1 ) or may be a separate memory. The program may include instructions that, when loaded into memory, cause the processor 150 to perform the available power estimation method. That is, the processor may perform an operation for an available power estimation method by executing program instructions.

Although the 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 made by those skilled in the art using the basic concept of the present invention defined in the following claims are also included in the scope of the present invention. that fall within the scope of the right.

Claims (15)

As a method for calculating the available power of a battery,
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, reflecting a gain determined by the cell voltage to at least one of the current or the resistance;
After reflecting the gain, estimating a maximum available current of the battery based on the measurement information and the resistance; and
Calculating available power of the battery based on the maximum available current
Available power calculation method comprising a. In paragraph 1,
The predetermined condition includes a condition in which the temperature of the battery is equal to or less than a predetermined temperature. In paragraph 1,
The step of reflecting the gain to at least one of the current or the resistance includes multiplying the resistance by a resistance gain that is inversely proportional to the cell voltage. In paragraph 1,
and reflecting the gain to at least one of the current or the resistance comprises multiplying the current by a current gain proportional to the cell voltage. In paragraph 1,
estimating a cell voltage after a requested period based on the cell voltage and the current;
Estimating the maximum available current includes 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.
How to calculate available power. In paragraph 5,
The step of calculating the available power is
estimating a final voltage based on the cell voltage after the requested period, the maximum available current, the current and the resistance; and
calculating the available power based on the maximum available current and the final voltage;
Available power calculation method comprising a. A battery comprising battery cells; and
The maximum available current of the battery is estimated based on the measurement information including the cell voltage and current of the battery and the resistance of the battery, and when the maximum available current is estimated, the current or the A processor that adjusts at least one of the resistors
A battery device comprising a. In paragraph 7,
Wherein the processor adjusts at least one of the current or the resistance by multiplying at least one of the current or the resistance by a gain determined by the cell voltage. In paragraph 8,
The gain includes a resistance gain that is inversely proportional to the cell voltage,
Wherein the processor adjusts the resistance by multiplying the resistance by the resistance gain. In paragraph 8,
the gain includes a current gain proportional to the cell voltage;
Wherein the processor adjusts the current by multiplying the current by the current gain. In paragraph 8,
Further comprising a memory for storing a corresponding relationship between the cell voltage and the gain;
The processor determines the gain corresponding to the cell voltage by referring to the memory.
battery device. In paragraph 7,
The processor
estimate a cell voltage after a requested period based on the cell voltage and the current;
Estimating the maximum available current based on the current, the cell voltage after the requested period, a target voltage and the resistance
battery device. In paragraph 12,
The processor
estimate a final voltage based on the cell voltage after the requested period, the maximum available current, the current and the resistance;
Estimating available power based on the maximum available current and the final voltage
battery device. In paragraph 12,
Wherein the processor multiplies the current by a current gain proportional to the cell voltage when estimating the maximum available current, and multiplies the resistance by a resistance gain inversely proportional to the cell voltage. A recording medium on which a program executed by a processor of a battery device is recorded,
The program, the processor,
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, reflecting a gain determined by the cell voltage to at least one of the current or the resistance;
After reflecting the gain, estimating a 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
recording media.

Images