JP7233270B2 - Rechargeable battery temperature estimation device and rechargeable battery temperature estimation method - Google Patents

Description

The present invention relates to a rechargeable battery temperature estimating device and a rechargeable battery temperature estimating method.

In recent years, in automobiles, etc., the number of electrical devices that operate on the power stored in rechargeable batteries has increased, and devices related to driving safety, such as electric steering and electric brakes, have also been equipped with rechargeable batteries. It is designed to be driven by Such rechargeable batteries are known to change their characteristics with temperature. For example, since the capacity of a rechargeable battery decreases as the temperature decreases, engine startability may decrease when the temperature is low. Therefore, from a safety perspective, it is necessary to know the temperature of the rechargeable battery. It is difficult to install a temperature detector inside and detect the internal temperature.

In Patent Document 1, a temperature detection value detected by a temperature detection unit that detects the external temperature of a rechargeable battery and a past temperature estimation value are subjected to a proportional calculation and an integral calculation to enable charging. A method for estimating battery temperature is presented.

Further, Patent Document 2 presents a method of calculating the chemical reaction heat and Joule heat due to charge/discharge current, calculating the sum of the heat, and estimating the battery temperature based on the sum.

JP 2012-192811 A JP 2017-157348 A

By the way, the techniques disclosed in Patent Documents 1 and 2 do not take into account the amount of electrolyte in the rechargeable battery. Therefore, if the amount of electrolyte increases or decreases, the accuracy of temperature estimation decreases. there is a point

The present invention has been made in view of the above circumstances, and provides a rechargeable battery temperature estimating device and a rechargeable battery temperature estimating method capable of accurately estimating the temperature regardless of changes in the amount of electrolyte. intended to provide.

In order to solve the above problems, one aspect of the present invention provides a rechargeable battery temperature estimating device for estimating the internal temperature of a rechargeable battery, wherein at least one of a current flowing through the rechargeable battery and an external temperature of the rechargeable battery is provided. Calculating means for calculating the internal temperature based on a relational expression showing the relationship between the internal temperature of the rechargeable battery and the internal temperature; Liquid volume estimating means for estimating the liquid volume of the rechargeable battery; correction means for correcting the coefficient of the relational expression based on the liquid amount estimated by the means; and the internal temperature calculated by the calculation means based on the relational expression whose coefficient is corrected by the correction means and output means for outputting.
According to such a configuration, it is possible to accurately estimate the temperature regardless of changes in the amount of electrolyte.

Further, one aspect of the present invention further includes temperature acquisition means for acquiring an external temperature detection value output from a temperature detection unit that detects the external temperature of the rechargeable battery, and the correction means has the relational expression A coefficient related to the external temperature is corrected, and the calculation means calculates the internal temperature of the rechargeable battery by applying the detected external temperature value to the relational expression with the corrected coefficient.
With such a configuration, it is possible to accurately estimate the internal temperature based on the external temperature.

Further, one aspect of the present invention further includes current acquisition means for acquiring a current detection value output from a current detection unit that detects a current flowing through the rechargeable battery, wherein the correction means obtains the current in the relational expression and the calculation means calculates the internal temperature of the rechargeable battery by applying the detected current value to the relational expression with the corrected coefficient.
With such a configuration, it is possible to accurately estimate the internal temperature based on the current flowing through the rechargeable battery.

In one aspect of the present invention, the calculating means calculates the internal temperature based on Joule heat and chemical reaction heat generated by current flowing through the rechargeable battery.
According to such a configuration, the internal temperature can be accurately estimated based on the two elements of Joule heat and heat of chemical reaction.

In one aspect of the present invention, the calculation means calculates the amount of heat generated by the current by multiplying the current detection value by a first coefficient, and calculates the external temperature detection value and the past internal temperature estimation value and performing a proportional operation including a second coefficient on the difference value, performing an integral operation including a third coefficient on the added value of the calorific value and the difference value, and performing the proportional operation The internal temperature is estimated by adding the values obtained by the calculation and the integral calculation, and the correction means calculates the first coefficient, the second coefficient, and the third coefficient based on the liquid amount. It is characterized by correcting.
According to such a configuration, the internal temperature can be accurately estimated by correcting the three coefficients.

Also, the present invention is characterized in that the calculation means changes the value of the first coefficient according to the current detection value detected by the current detection section.
According to such a configuration, it is possible to more accurately estimate the internal temperature by correcting the first coefficient according to the value of the current.

Further, according to one aspect of the present invention, the calculating means sets the first coefficient differently during charging and discharging of the rechargeable battery.
According to such a configuration, the internal temperature can be estimated more accurately by changing the first coefficient during charging and discharging.

Also, in one aspect of the present invention, the calculating means obtains the estimated value of the internal temperature based on the following formula: Tb(n)=VT_prop(n)+VT_integ(n) where VT_prop(n)= dT(n)×G_prop VT_integ(n)=dT(n)×G_integ+VT_integ(n−1)+I(n)×α and Tb(n) is an estimate of the internal temperature of the rechargeable battery, dT(n ) is the difference value between the external temperature detection value detected by the temperature detection unit and the past internal temperature estimation value, α is the first coefficient related to the calorific value, and G_prop is the first coefficient of the proportional calculation. 2 coefficients, G_integ is the third coefficient of the integral calculation, and I(n) is the current detection value detected by the current detection unit.
According to such a configuration, it is possible to more accurately estimate the internal temperature based on the calculation formula.

In one aspect of the present invention, the output means estimates and outputs the temperature of the rechargeable battery mounted on the vehicle, and the processor of the vehicle estimates the temperature output from the output means. The operating state of the vehicle is changed based on.
According to such a configuration, it is possible to efficiently control the vehicle based on the internal temperature of the rechargeable battery.

According to another aspect of the present invention, there is provided a rechargeable battery temperature estimation method for estimating an internal temperature of a rechargeable battery, wherein at least one of a current flowing through the rechargeable battery and an external temperature of the rechargeable battery; A calculation step of calculating the internal temperature based on a relational expression showing the relationship between the internal temperature of the rechargeable battery, a liquid volume estimation step of estimating the liquid volume of the rechargeable battery, and the liquid volume estimated in the liquid volume estimation step a correction step of correcting the coefficient of the relational expression based on the liquid amount; an output step of outputting the internal temperature calculated in the calculation step based on the relational expression whose coefficient is corrected by the correction step; characterized by having
According to such a method, it is possible to accurately estimate the temperature regardless of changes in the amount of electrolyte.

According to another aspect of the present invention, there is provided a rechargeable battery temperature estimating apparatus for estimating an internal temperature of a rechargeable battery, comprising: a processor; and a memory for storing a group of instructions, based on a relational expression showing a relationship between at least one of a current flowing through the rechargeable battery and an external temperature of the rechargeable battery, and the internal temperature of the rechargeable battery. to calculate the internal temperature, estimate the liquid level of the rechargeable battery, correct the coefficient of the relational expression based on the estimated liquid level, and calculate the coefficient based on the corrected relational expression. and outputting the internal temperature.
According to such a configuration, it is possible to accurately estimate the temperature regardless of changes in the amount of electrolyte.

According to the present invention, it is possible to provide a rechargeable battery temperature estimating device and a rechargeable battery temperature estimating method capable of accurately estimating the temperature regardless of changes in the amount of electrolyte.

1 is a diagram showing a configuration example of a rechargeable battery temperature estimating device according to an embodiment of the present invention; FIG. 2 is a block diagram showing a detailed configuration example of a control unit in FIG. 1; FIG. 3 is a block diagram showing an algorithm implemented when the program shown in FIG. 2 is executed; FIG. FIG. 3 is a diagram showing the relationship between the size of a rechargeable battery and the amount of electrolyte. It is a figure which shows the relationship between sulfuric acid concentration and specific heat. 4 is a flow chart for explaining the operation of the embodiment of the present invention; 4 is a flow chart for explaining the operation of the embodiment of the present invention; 4 is a flow chart for explaining the operation of the embodiment of the present invention; It is a figure for demonstrating the effect of this invention. Figure 4 shows a modified embodiment of Figure 3; Figure 4 shows a modified embodiment of Figure 3; Figure 4 shows a modified embodiment of Figure 3; Figure 4 shows a modified embodiment of Figure 3; Figure 4 shows a modified embodiment of Figure 3; Figure 4 shows a modified embodiment of Figure 3; Figure 4 shows a modified embodiment of Figure 3;

Next, embodiments of the present invention will be described.

(A) Description of Configuration of Embodiment of the Present Invention FIG. 1 is a diagram showing a power supply system of a vehicle having a rechargeable battery temperature estimating device according to an embodiment of the present invention. In this figure, the rechargeable battery temperature estimating device 1 has a controller 10, a voltage detector 11, a current detector 12, and a temperature detector 13 as main components, and estimates the internal temperature of the rechargeable battery 14. and notifies an unillustrated higher-level device (for example, an ECU (Electric Control Unit)).

Here, control unit 10 refers to outputs from voltage detection unit 11 , current detection unit 12 , and temperature detection unit 13 to estimate the internal temperature of rechargeable battery 14 . Further, the control unit 10 detects the state of the rechargeable battery 14 and controls the charging state of the rechargeable battery 14 by controlling the voltage generated by the alternator 15 . Voltage detection unit 11 , current detection unit 12 , and temperature detection unit 13 may be built in control unit 10 or may be provided outside control unit 10 .

The voltage detection unit 11 detects the terminal voltage of the rechargeable battery 14 and supplies it as a voltage detection signal to the CPU 10a via the I/F 10e. The current detection unit 12 detects the current flowing through the rechargeable battery 14 and supplies it as a current detection signal to the CPU 10a via the I/F 10e.

The temperature detection unit 13 is composed of, for example, a thermistor or a thermocouple, is arranged in a position close to the battery case of the rechargeable battery 14, detects the external temperature of the rechargeable battery 14, and receives the I/F 10e as a temperature detection signal. supplied to the CPU 10a via the

In the present embodiment, the "internal temperature" refers to the temperature of the electrolyte of the rechargeable battery 14. As shown in FIG. Further, the external temperature is the temperature outside the rechargeable battery 14, for example, the ambient temperature of the environment in which the rechargeable battery 14 is placed or the temperature of the resin forming the battery case.

Of course, as the external temperature, it is also possible to use the temperature of the electrode terminal (not shown) of the rechargeable battery 14 itself, the ambient temperature, or the temperature inside the spout plug (not shown). Since the internal temperature is estimated from the electrolyte, it is desirable that the temperature detection unit 13 be provided near the part of the battery case filled with the electrolyte, for example. Also, as will be described later, the internal temperature is affected by heat from the engine 16, so the temperature detection unit 13 can be installed at a position as close to the engine 16 as possible.

Instead of the control unit 10 controlling the voltage generated by the alternator 15 to control the state of charge of the rechargeable battery 14, for example, an ECU (not shown) may control the state of charge.

The rechargeable battery 14 is composed of a rechargeable battery having an electrolytic solution, such as a lead-acid battery, a nickel-cadmium battery, or a nickel-hydrogen battery, and is charged by the alternator 15 to drive the starter motor 17 to start the engine. and supplies power to the load 18 . Note that the rechargeable battery 14 is configured by connecting a plurality of cells in series. Alternator 15 is driven by engine 16 to generate AC power which is converted to DC power by a rectifier circuit to charge rechargeable battery 14 . The alternator 15 is controlled by the controller 10 and is capable of adjusting the generated voltage.

The engine 16 is configured by, for example, a reciprocating engine such as a gasoline engine and a diesel engine, a rotary engine, or the like, and is started by a starter motor 17 to drive drive wheels through a transmission to provide propulsion to the vehicle. to generate electric power. The starter motor 17 is composed of, for example, a direct-current motor, and generates rotational force by electric power supplied from the rechargeable battery 14 to start the engine 16 . The load 18 includes, for example, an electric steering motor, a defogger, a seat heater, an ignition coil, a car audio system, a car navigation system, and the like, and operates with power from the rechargeable battery 14 .

FIG. 2 is a diagram showing a detailed configuration example of the control unit 10 shown in FIG. As shown in this figure, the control unit 10 includes a CPU (Central Processing Unit) 10a, a ROM (Read Only Memory) 10b, a RAM (Random Access Memory) 10c, a communication unit 10d, an I/F (Interface) 10e, and It has a bus 10f. Here, the CPU 10a as a processor controls each part based on the program 10ba stored in the ROM 10b. The ROM 10b is configured by a semiconductor memory or the like, and stores a program 10ba or the like executable by the CPU 10a. The RAM 10c is configured by a semiconductor memory or the like, and stores data generated when executing the program 10ba and data 10ca such as a table to be described later. The communication unit 10d communicates with an ECU or the like, which is a host device, and notifies the host device of detected information or control information. The I/F 10e converts signals supplied from the voltage detection unit 11, the current detection unit 12, and the temperature detection unit 13 into digital signals and takes them in, and supplies drive currents to the alternator 15, the starter motor 17, and the like. to control them. The bus 10f is a group of signal lines for interconnecting the CPU 10a, ROM 10b, RAM 10c, communication section 10d, and I/F 10e and enabling information exchange therebetween. A DSP (Digital Signal Processor), FPGA (Field Programmable Gate Array), or ASIC (Application Specified Integrated Circuit) may be used instead of the CPU 10a.

FIG. 3 is a block diagram showing a temperature estimation algorithm implemented by executing program 10ba shown in FIG. Algorithm 30 shown in this figure has addition/subtraction circuit 31, constant multiple circuits 32 to 34, addition circuits 35 and 37, integration circuit 36, delay circuit 38, electrolyte amount estimation section 39, and coefficient correction section 40. there is

Here, the addition/subtraction circuit 31 subtracts the previous temperature estimation value Tb(n−1) output from the delay circuit 38 from the temperature detection value Ta(n) supplied from the temperature detection unit 13, and obtains output the value as the difference value dT(n). Note that n indicates the number of times of processing.

A constant multiple circuit 32 outputs a value obtained by multiplying the difference value dT(n) output from the addition/subtraction circuit 31 by G_integ, which is an integral gain. A constant multiplication circuit 33 outputs a value obtained by multiplying the difference value dT(n) output from the addition/subtraction circuit 31 by G_prop, which is a proportional gain.

The constant multiplier circuit 34 receives the current detection value I detected by the current detection unit 12 and outputs a value obtained by multiplying the current detection value I by a coefficient α. The adder circuit 35 adds the value output from the constant multiplier circuit 32 and the value output from the constant multiplier circuit 34 and outputs the result.

The integration circuit 36 integrates the value output from the addition circuit 35 and outputs the result. The adder circuit 37 adds the output value of the constant multiplier circuit 33 and the output value of the integration circuit 36, and outputs the obtained value as the estimated temperature value Tb(n).

The delay circuit 38 delays the temperature estimated value Tb(n) output from the adder circuit 37 by one sample period, and outputs it to the addition/subtraction circuit 31 as Tb(n−1).

The above block diagram is represented by the following equations (1) to (3).
Tb(n)=VT_prop(n)+VT_integ(n) (1)

here,
VT_prop(n)=dT(n)×G_prop (2)
again,
VT_integ(n)=dT(n)×G_integ+VT_integ(n−1)
+I(n)×α
... (3)

As will be described later, the electrolyte amount estimation unit 39 estimates the amount of electrolyte in the rechargeable battery 14 based on the time integral value of the current during charging, and notifies the coefficient correction unit 40 of the estimated amount.

The coefficient corrector 40 corrects the constants of the constant multiplying circuits 32 to 34 based on the electrolyte amount estimated by the electrolyte amount estimator 39 .

(B) Description of Operation of Embodiment of the Present Invention Next, an outline of the operation of this embodiment will be described. In this embodiment, the algorithm of the block diagram shown in FIG. 3 is realized by executing the program 10ba shown in FIG. In the algorithm shown in FIG. 3, the electrolytic solution amount estimator 39 estimates the electrolytic solution amount and notifies the coefficient correction unit 40 of it.

FIG. 4 shows the sizes of rechargeable batteries and the amount of electrolyte at the upper and lower limits for each size rechargeable battery. The horizontal axis of FIG. 4 indicates the type of rechargeable battery (EN standard type names LN0 to LN6), and the vertical axis indicates the electrolyte volume (L). In addition, the circles in FIG. 4 indicate the amount of electrolytic solution at the lower limit (position of the LOWER line of the rechargeable battery 14), and the squares indicate the amount of electrolytic solution at the upper limit (position of the UPPER line of the rechargeable battery 14). showing. From this figure, a volume change of about 15 to 20% occurs between the upper limit and the lower limit. Therefore, when the electrolyte decreases, the volume of the electrolytic solution decreases, so the heat capacity of the rechargeable battery 14 decreases.

FIG. 5 is a diagram showing the relationship between the concentration of sulfuric acid, which is the main component of the electrolyte, and the specific heat. The horizontal axis in FIG. 5 indicates the concentration (%) of sulfuric acid, and the vertical axis indicates the specific heat (J/kg° C.). Since sulfuric acid is non-volatile, the concentration of sulfuric acid increases as the water evaporates due to liquid reduction. As the concentration of sulfuric acid increases, the specific heat decreases, as shown in FIG. Therefore, when the liquid decreases, the concentration of sulfuric acid in the rechargeable battery 14 increases, and the heat capacity decreases.

Since the algorithm shown in FIG. 3 estimates the internal temperature based on the thermal equivalent circuit of the rechargeable battery 14, it is necessary to correct the coefficient when the heat capacity of the thermal equivalent circuit changes. In this embodiment, the coefficient corrector 40 corrects the constants of the constant multiplier circuits 32 to 34 based on the amount of electrolyte.

More specifically, the coefficient correction unit 40 corrects (sets) the coefficient α of the constant multiplier circuit 32 according to the amount of electrolyte. Here, α is a coefficient whose value changes depending on the value of the current flowing through the rechargeable battery 14 and the direction of the current. More specifically, the value of the coefficient α of the constant multiplier circuit 34 can be expressed as follows.

When the rechargeable battery 14 is charged α=fc(I) (4)

When the rechargeable battery 14 is discharged α=fd(I) (5)

Here, fc(I) is a function with the current I as an independent variable and a function whose value changes according to the charging current I. Also, fd(I) is a function with the current I as an independent variable and a function whose value changes according to the discharge current I.

fc(I) and fd(I) can be determined by actual measurement. The current dependence of fc(I) and fd(I) not only changes with the amount of electrolyte solution as described above, but also with the presence or absence of an insulator for protecting the rechargeable battery 14 from temperature changes. It varies depending on the size, the number of electrode plates, the type (normal liquid type, seal type), and the like. Therefore, fc(I) and fd(I) are obtained individually depending on the presence or absence and size of insulators, the number and types of electrode plates (normal liquid type, seal type), and the like. Further, fc(I) and fd(I) corresponding to the amount of electrolytic solution are obtained, stored in the coefficient correction unit 40 in advance, and fc(I) corresponding to the amount of electrolytic solution supplied from the electrolytic solution amount estimating unit 39 ) and fd(I) to correct the coefficients, the coefficients can be set appropriately.

Alternatively, α=fc(I)×ac and α=fd(I)×ad, and by selecting and multiplying ac and ad according to the amount of electrolytic solution, an appropriate coefficient can be set.

That is, as a method of correcting the coefficient α according to the electrolyte amount, there is, for example, the following method. Of course, the method is not limited to these as long as the method can appropriately set the coefficient α based on the amount of electrolytic solution.

(A) An appropriate α can be obtained by obtaining a relational expression showing the relationship between the amount of electrolytic solution and α, and applying the amount of electrolytic solution to the relational expression.
(B) By storing information indicating the relationship between the amount of electrolyte and α in a table and obtaining information corresponding to the amount of electrolyte from the table, an appropriate α can be obtained.
(C) An appropriate α can be obtained by multiplying the above-described formulas (4) and (5) by predetermined coefficients ad and ac according to the amount of electrolyte.

Taking an in-vehicle lead-acid battery as an example, the discharge reaction of the lead-acid battery is an endothermic reaction, and the charge reaction is an exothermic reaction due to chemical reaction heat and Joule heat. Therefore, by using functions fc(I) and fd(I) suitable for charging and discharging separately, the internal temperature can be obtained with high accuracy.

Also, fc(I) and fd(I) change depending on the state of deterioration of the rechargeable battery 14 . For example, in the case of a lead-acid battery, as the deterioration progresses, the internal resistance increases, resulting in an increase in Joule heat (I ² ×R). Therefore, by correcting fc(I) and fd(I) according to the deterioration state of the rechargeable battery 14, it is possible to accurately estimate the internal temperature regardless of the deterioration state.

Further, the coefficient correction unit 40 corrects the integral gain G_integ according to the amount of electrolyte solution and sets it in the constant multiplier circuit 32 , and corrects the proportional gain G_prop and sets it in the constant multiplier circuit 33 . More specifically, the coefficient correction unit 40 can correct G_integ and G_prop by the following method. Of course, the method is not limited to these as long as the coefficient G_integ and the coefficient G_prop are appropriately set based on the electrolyte amount.

(D) Appropriate coefficients G_integ and G_prop can be obtained by obtaining relational expressions indicating the relationship between the electrolyte amount and the coefficient G_integ and the coefficient G_prop, respectively, and applying the electrolyte amount to the relational expressions.
(E) By storing information indicating the relationship between the amount of electrolytic solution and the coefficient G_integ and G_prop in a table and obtaining information corresponding to the amount of electrolytic solution from the table, it is possible to obtain an appropriate coefficient G_integ and G_prop. .
(F) Appropriate coefficients G_integ and G_prop can be obtained by multiplying coefficients G_integ and G_prop by predetermined coefficients a_integ and coefficient a_prop corresponding to the amount of electrolytic solution.

Once set up, the internal temperature of rechargeable battery 14 is estimated based on algorithm 30 shown in FIG. More specifically, the current detection signal output from the current detection unit 12 and the temperature detection value output from the temperature detection unit 13 are sampled at predetermined intervals, and the temperature estimation value is output based on proportional calculation and integral calculation. . Then, the temperature estimated value obtained in this manner is supplied to an ECU (not shown), and the ECU performs temperature correction of, for example, a state of charge (SOC) based on the supplied temperature estimated value. process.

That is, the addition/subtraction circuit 31 inputs the temperature detection value Ta(n) supplied from the temperature detection unit 13, and the temperature estimation value Tb(n−1) supplied from the delay circuit 38 one sampling period before. Add and output as dT(n).

A constant multiplier circuit 32 multiplies dT(n) output from the addition/subtraction circuit 31 by G_integ, which is an integral gain, and outputs the result. A constant multiplier circuit 33 multiplies dT(n) output from the addition/subtraction circuit 31 by G_prop, which is a proportional gain, and outputs the result.

A constant multiplier circuit 34 multiplies the current detection value I(n) supplied from the current detection unit 12 by a coefficient α and outputs the result.

The adder circuit 35 adds the output value of the constant multiplier circuit 34 and the output value of the constant multiplier circuit 32 and supplies the result to the integrating circuit 36 . The integrating circuit 36 integrates the output value of the adding circuit 35 and supplies it to the adding circuit 37 . The adding circuit 37 adds the output value of the integrating circuit 36 and the output value of the constant multiplying circuit 33 and outputs the result as an estimated temperature value Tb(n) regarding the internal temperature of the rechargeable battery 14 .

The delay circuit 38 delays the output value of the addition circuit 37 by one sampling period and supplies it to the addition/subtraction circuit 31 .

By the above operation, the internal temperature of rechargeable battery 14 can be estimated based on the current detection value by current detection unit 12 and the temperature detection value by temperature detection unit 13 .

As described above, in the embodiment of the present invention, the amount of electrolyte is obtained, α, G_integ, and G_prop are corrected according to the amount of electrolyte, and based on algorithm 30 of FIG. Since the internal temperature of the rechargeable battery 14 is estimated, the internal temperature of the rechargeable battery 14 can be accurately estimated regardless of the amount of electrolyte.

Next, with reference to FIG. 6, the details of the processing executed by the control unit 10 shown in FIG. 1 in order to realize the function of the electrolytic solution amount estimating unit 39 shown in FIG. 3 will be described. When the process of the flowchart shown in FIG. 6 is started, the following steps are executed.

In step S10, the CPU 10a acquires the voltage detection value V detected by the voltage detection unit 11 via the I/F 10e after a predetermined time (for example, several hours) has elapsed since the engine 16 was stopped. is OCV (Open Circuit Voltage).

In step S11, the CPU 10a determines whether the OCV measured in step S10 has decreased by a predetermined value or more compared to the time of the previous measurement. Otherwise, the process proceeds to step S12 (step S11: N), otherwise the process proceeds to step S14.

In step S12, when the OCV has decreased by a predetermined value or more, the CPU 10a determines that fluid replacement has been performed (distilled water has been replenished in response to the decrease in the electrolyte). That is, since the OCV decreases when the fluid is replaced, it can be determined that the fluid has been replaced when the OCV has decreased by a predetermined value or more. Note that the value that serves as the criterion for determination can be obtained, for example, by actual measurement.

In step S13, the CPU 10a causes the electrolytic solution amount estimator 39 of the algorithm shown in FIG. 3 to set the estimated value of the electrolytic solution amount to the upper limit level. That is, since fluid replacement is normally performed up to the upper limit level of the rechargeable battery 14, when it is determined in step S12 that fluid replacement has been performed, the amount of electrolyte solution is set to the upper limit level.

In step S14, the CPU 10a estimates the SOC of the rechargeable battery 14 by applying the OCV measured in step S10 to the relational expression between OCV and SOC. Instead of obtaining the SOC from the OCV, the SOC may be obtained by cumulatively adding the current flowing through the rechargeable battery 14 .

In step S15, the CPU 10a refers to the SOC obtained in step S14 and determines whether or not the SOC is fully charged. If it is determined that the SOC is fully charged (step S15: Y), step S16 otherwise (step S15: N), the process proceeds to step S19.

In step S16, the CPU 10a acquires the current detection value I detected by the current detection unit 12 via the I/F 10e during charging of the rechargeable battery 14, and sets it as the current detection value I during charging.

In step S17, the CPU 10a detects the charging time T. FIG. For example, if the measurement in step S16 is performed at a predetermined cycle Ts (for example, every few seconds), the charging time T can be Ts.

In step S18, the CPU 10a sets β1×I×T as the liquid decrease amount. That is, when the rechargeable battery 14 is fully charged and then charged, the current flowing through the rechargeable battery 14 is mainly used for the electrolysis of the electrolyte. The amount of liquid decrease can be estimated from the value multiplied by β1.

In step S19, the CPU 10a obtains the current detection value I detected by the current detection unit 12 via the I/F 10e during charging of the rechargeable battery 14, and sets it as the current detection value I during charging.

In step S20, the CPU 10a detects the charging time T. FIG. For example, if the measurement in step S16 is performed at a predetermined cycle Ts (for example, every few seconds), the charging time T can be Ts.

In step S21, the CPU 10a sets β2×I×T as the liquid decrease amount. That is, even when the rechargeable battery 14 is not fully charged, the electrolyte in the rechargeable battery 14 is slightly electrolyzed. amount can be estimated. Note that β2<β1.

In step S22, the CPU 10a cumulatively adds the liquid decrease amount. That is, the liquid reduction amount obtained in step S18 or step S21 is cumulatively added to obtain the liquid reduction amount.

In step S23, the CPU 10a estimates the amount of electrolytic solution at that point in time based on the liquid decrease amount obtained in step S22. For example, after a new rechargeable battery 14 is installed, or after the upper limit level is set in step S13, the cumulative addition value of the amount of liquid decrease obtained in step S22 is subtracted from the upper limit value. By doing so, the amount of electrolytic solution at that time is estimated. The amount of electrolytic solution obtained in this manner is supplied to the electrolytic solution amount estimating section 39 shown in FIG.

In step S24, the CPU 10a determines whether or not to continue the process. If it is determined to continue the process (step S24: Y), the process returns to step S10 to repeat the same process as described above. If (step S24: N), the process is terminated.

Next, with reference to FIG. 7, the details of the processing executed by the control unit 10 shown in FIG. 1 in order to realize the function of the coefficient correction unit 40 shown in FIG. 3 will be described. When the process of the flowchart shown in FIG. 7 is started, the following steps are executed.

In step S30, the CPU 10a acquires the electrolyte amount estimated in step S23 of FIG.

In step S31, the CPU 10a corrects the charging α shown in the above-described equation (4) based on the amount of electrolytic solution obtained in step S30, and sets the algorithm shown in FIG. As the correction method, there are the methods (A) to (C) described above.

At step S32, the CPU 10a corrects the discharge .alpha. shown in the above-described equation (5) based on the amount of electrolytic solution obtained at step S30, and sets the algorithm shown in FIG. As the correction method, there are the methods (A) to (C) described above.

In step S33, the CPU 10a corrects the integral gain G_integ based on the electrolyte amount obtained in step S30, and sets it to the algorithm shown in FIG. As the correction method, there are the methods (D) to (F) described above.

In step S34, the CPU 10a corrects G_prop, which is a proportional gain, based on the amount of electrolyte obtained in step S30, and sets the algorithm shown in FIG. As the correction method, there are the methods (D) to (F) described above.

In step S35, the CPU 10a determines whether or not to continue the process. If it is determined to continue the process (step S35: Y), the process returns to step S30 to repeat the same process as described above. If (step S35: N), the process is terminated.

Next, with reference to FIG. 8, processing regarding the coefficient α will be described. When the process of the flowchart shown in FIG. 8 is started, the following steps are executed.

In step S50, the CPU 10a acquires the current detection value I detected by the current detection section 12 via the I/F 10e. The current detection value can be defined as positive when the rechargeable battery 14 is being charged, and can be defined as being negative when the rechargeable battery 14 is being discharged. Of course, the opposite definition is also possible.

In step S51, the CPU 10a calculates the absolute value Ia of the current detection value I obtained in step S50. For example, if the current obtained in step S50 is -25A, 25A is obtained.

In step S52, the CPU 10a compares the absolute value Ia of the current detection value calculated in step S51 with a predetermined threshold Th. (step S52: N), the process proceeds to step S59. For example, if Ia>Th (1A), the process proceeds to step S53.

In step S53, the CPU 10a determines whether or not the rechargeable battery 14 is being discharged. If it is determined that the battery is being discharged (step S53: Y), the process proceeds to step S54; otherwise (step S53: N). to step S55. For example, when the current detection value obtained in FIG. 3 is negative, it can be determined that the battery is discharging.

In step S54, the CPU 10a sets α shown in Equation (5) for the constant multiplier circuit . The value of α is corrected according to the amount of electrolytic solution by the process of FIG. 7 described above.

In step S55, the CPU 10a sets α shown in Equation (4) for the constant multiplier circuit . The value of α is corrected according to the amount of electrolytic solution by the process of FIG. 7 described above.

In step S56, it is determined whether or not the rechargeable battery 14 has deteriorated. If it is determined that it has deteriorated (step S56: Y), the process proceeds to step S57; otherwise (step S56: N). to step S58. For example, the voltage and current when starting the engine 16 are measured by the voltage detection unit 11 and the current detection unit 12, and SOH (State of Health) indicating the deterioration of the rechargeable battery 14 is obtained from these. If the SOH is smaller than a predetermined threshold value, it is determined that deterioration has occurred, and the process proceeds to step S57.

At step S<b>57 , the CPU 10 a corrects the value of α according to the state of deterioration of the rechargeable battery 14 . More specifically, when the deterioration progresses, the internal resistance increases and the amount of Joule heat generated increases. to correct.

In step S58, the CPU 10a executes temperature estimation processing with charge/discharge correction. More specifically, in FIG. 3, the process of estimating the internal temperature of the rechargeable battery 14 is performed in consideration of the output from the constant multiplier circuit 34 .

In step S59, the CPU 10a executes internal temperature estimation processing without charge/discharge correction. More specifically, in FIG. 3, the process of estimating the internal temperature of the rechargeable battery 14 is executed without considering the output from the constant multiplier circuit 34 (with the constant multiplier circuit 34 stopped).

FIG. 9 is a diagram showing estimation results of liquid temperature according to the embodiment of the present invention. Here, FIG. 9A shows changes in outside air temperature. More specifically, the horizontal axis of FIG. 9A indicates time, and the vertical axis indicates temperature.

FIG. 9(B) shows the relationship between the estimated value and the measured value of the liquid temperature of the rechargeable battery 14 under the outside air temperature shown in FIG. 9(A). The two-dot chain line in FIG. 9(B) indicates the measured value of the liquid temperature change in the normal time when the liquid decrease does not occur. A dashed line with a long interval indicates an estimated value of liquid temperature change in a normal time when liquid decrease does not occur. The dashed-dotted line shows the measured value of the change in liquid temperature when the liquid is reduced. A dashed line with a short interval indicates an estimated value of the liquid temperature change at the time of liquid reduction in which liquid reduction occurs. It can be seen from the comparison between the one-dot chain line and the dashed line with short intervals and the comparison between the two-dot chain line and the dashed line with long intervals that they show close values.

As described above, according to the embodiments of the present invention, the internal temperature of the rechargeable battery 14 can be accurately estimated regardless of the amount of electrolyte.

(C) Description of Modified Embodiment The above-described embodiment is merely an example, and needless to say, the present invention is not limited to the case described above. For example, in the above embodiment, the algorithm 30 shown in FIG. 3 is used, but the present invention is not limited to only FIG. 3, and algorithms 30 other than those shown in FIG. 3 may be used.

For example, algorithm 30 shown in FIGS. 10-16 may be used. More specifically, FIG. 10 excludes the constant multiplier circuit 32 when compared to FIG. Other than this, it is the same as FIG. In the configuration example of FIG. 10 , the coefficient correction unit 40 corrects the values of the constant multiple circuits 32 and 34 based on the electrolyte amount estimated by the electrolyte amount estimation unit 39 . Accordingly, the internal temperature can be estimated based on the heat generated by the current and the integral gain using the coefficient α and the coefficient G_integ corrected according to the electrolyte amount.

FIG. 11 shows another configuration example. In FIG. 11, as compared with FIG. 3, the constant multiplier circuit 32 is omitted. Other configurations are the same as those in FIG. In the configuration example of FIG. 11 , the coefficient correction unit 40 corrects the values of the constant multiple circuits 33 and 34 based on the electrolyte amount estimated by the electrolyte amount estimation unit 39 . Thereby, the internal temperature can be estimated based on the heat generated by the electric current and the proportional gain using the coefficient α and the coefficient G_prop corrected according to the electrolyte amount.

FIG. 12 shows another configuration example. In FIG. 12, as compared with FIG. 3, the constant multiplier circuit 34 is omitted. Other configurations are the same as those in FIG. In the configuration example of FIG. 12 , the coefficient correction unit 40 corrects the values of the constant multiple circuits 32 and 33 based on the electrolyte amount estimated by the electrolyte amount estimation unit 39 . Thereby, the internal temperature can be estimated based on the integral gain and the proportional gain using the coefficient G_integ and the coefficient G_prop corrected according to the electrolyte amount.

FIG. 13 shows another configuration example. In FIG. 13, the constant multiple circuits 32 and 33, the adder circuit 37, and the delay circuit 38 are excluded as compared with FIG. Other configurations are the same as those in FIG. In the configuration example of FIG. 13 , the coefficient correction unit 40 corrects the value of the constant multiplier circuit 34 based on the electrolyte amount estimated by the electrolyte amount estimation unit 39 . Thereby, the internal temperature can be estimated based on the heat generated by the electric current using the coefficient α corrected according to the electrolyte amount.

FIG. 14 shows another configuration example. In FIG. 14, the constant multiple circuits 33 and 34 and the adder circuit 37 are excluded as compared with FIG. Other configurations are the same as those in FIG. In the configuration example of FIG. 14 , the coefficient correction unit 40 sets the value of the constant multiple circuit 32 based on the electrolyte amount estimated by the electrolyte amount estimation unit 39 . Thereby, the internal temperature can be estimated based on the integral gain using the coefficient G_integ corrected according to the electrolyte amount.

FIG. 15 shows another configuration example. In FIG. 15, the constant multiplier circuits 32 and 34, the integration circuit 36, and the addition circuits 35 and 37 are excluded as compared with FIG. Other configurations are the same as those in FIG. In the configuration example of FIG. 15 , the coefficient corrector 40 corrects the value of the constant multiple circuit 33 based on the electrolyte amount estimated by the electrolyte amount estimator 39 . Thereby, the internal temperature can be estimated based on the proportional gain using the coefficient G_prop corrected according to the electrolyte amount.

FIG. 16 shows another configuration example. In FIG. 16, the constant multiple circuits 33 and 34 and the adder circuits 35 and 37 are excluded as compared with FIG. Also, an addition circuit 50 is added, and the sum of the initial temperature and the output Tb(n) is input to the delay circuit 38 . Other configurations are the same as those in FIG. In the configuration example of FIG. 16 , the coefficient corrector 40 corrects the value of the constant multiple circuit 32 based on the electrolyte amount estimated by the electrolyte amount estimator 39 . Further, in the example of FIG. 16, since the initial temperature can be set, for example, the temperature at the start of the engine 16 can be set as the initial temperature, and the internal temperature can be estimated based on the integral gain. Thereby, the internal temperature can be estimated based on the integral gain using the coefficient G_integ corrected according to the electrolyte amount.

The flowcharts shown in FIGS. 6 to 8 are examples, and the present invention is not limited only to these flowcharts.

In the above embodiment, the amount of electrolyte solution is estimated based on the time integral value of the current during charging. A sensor may be arranged to estimate the amount of electrolyte based on these temperature differences. That is, as described above, since the temperature of the electrolyte rises during charging, the amount of electrolyte can be estimated by detecting the temperature boundary with the temperature sensor.

Further, in each of the above embodiments, the temperature estimated value is supplied to the ECU, and the ECU executes processing such as temperature correction of the charging rate based on the temperature estimated value. The rechargeable battery temperature estimating device 1 may estimate the charging rate based on the temperature estimated value. Of course, the ECU may obtain an index value other than the SOC (for example, SOF (State of Function), SOH) that indicates the state of the rechargeable battery 14 based on the estimated temperature value. Also, the operating state of the vehicle may be controlled based on these obtained index values. For example, in the case of SOC, the ECU can control the alternator 15 to charge the rechargeable battery 14 . Further, since SOH indicates the state of deterioration of the rechargeable battery 14, when the rechargeable battery 14 has deteriorated by a predetermined value or more due to SOH, a message prompting replacement of the rechargeable battery 14 may be presented. . Regarding the SOF, for example, when the engine 16 is stopped when the vehicle is stopped at a traffic light or the like, that is, when performing a so-called idling stop, it is determined by the SOF whether or not the engine 16 can be restarted. The engine 16 may be stopped accordingly. As described above, according to the present invention, the temperature of the rechargeable battery can be estimated with high accuracy, so the accuracy of estimating the index value such as SOC, SOF, or SOH that indicates the state of the rechargeable battery can be improved. Therefore, when the host control device controls the operating state of the vehicle based on these index values, it is possible to safely control the vehicle and to improve the fuel efficiency.

1 Rechargeable Battery Temperature Estimating Device 10 Control Unit 10a CPU
10b ROM
10ba program 10c RAM
10ca data 10d communication unit 10e I/F
10f bus 11 voltage detector 12 current detector 13 temperature detector 14 rechargeable battery 15 alternator 16 engine 17 starter motor 18 load 30 algorithm 31 addition/subtraction circuit 32 to 34 constant multiple circuit 35, 37 addition circuit 36 integration circuit 38 delay circuit 39 Electrolyte amount estimator 40 Coefficient corrector 50 Adder circuit

Claims (11)

In a rechargeable battery temperature estimating device for estimating the internal temperature of a rechargeable battery,
calculation means for calculating the internal temperature based on a relational expression showing the relationship between at least one of the current flowing through the rechargeable battery and the external temperature of the rechargeable battery and the internal temperature of the rechargeable battery;
a liquid volume estimating means for estimating the liquid volume of the rechargeable battery;
correction means for correcting the coefficient of the relational expression based on the liquid volume estimated by the liquid volume estimation means;
output means for outputting the internal temperature calculated by the calculation means based on the relational expression whose coefficient is corrected by the correction means;
A rechargeable battery temperature estimating device comprising: further comprising temperature acquisition means for acquiring an external temperature detection value output from a temperature detection unit that detects the external temperature of the rechargeable battery;
The correction means corrects the coefficient related to the external temperature of the relational expression,
The calculation means applies the external temperature detection value to the coefficient-corrected relational expression to calculate the internal temperature of the rechargeable battery.
The rechargeable battery temperature estimating device according to claim 1, characterized in that: further comprising current acquisition means for acquiring a current detection value output from a current detection unit that detects current flowing through the rechargeable battery;
The correcting means corrects the coefficient related to the current in the relational expression,
The calculating means applies the current sensed value to the coefficient-corrected relational expression to calculate the internal temperature of the rechargeable battery.
The rechargeable battery temperature estimating device according to claim 2 , characterized in that: 4. The rechargeable battery temperature estimating device according to claim 3, wherein said calculating means calculates said internal temperature based on Joule heat and chemical reaction heat generated by current flowing through said rechargeable battery. The calculation means are
calculating the amount of heat generated by the current by multiplying the current detection value by a first coefficient;
calculating a difference value between the detected external temperature value and the past estimated value of the internal temperature;
performing a proportional operation including a second coefficient on the difference value;
performing an integration operation including a third coefficient on the added value of the calorific value and the difference value;
estimating the internal temperature by adding the values obtained by the proportional operation and the integral operation;
The correcting means is
correcting the first coefficient, the second coefficient, and the third coefficient based on the liquid amount;
The rechargeable battery temperature estimating device according to claim 4, characterized in that: 6. The rechargeable battery temperature estimating device according to claim 5, wherein said calculating means changes the value of said first coefficient according to said current detection value detected by said current detection section. 6. The rechargeable battery temperature estimating device according to claim 5, wherein the calculating means sets the first coefficient differently during charging and discharging of the rechargeable battery. The calculating means obtains an estimate of the internal temperature based on the following formula:
Tb(n) = VT_prop(n) + VT_integ(n)
here,
VT_prop(n) = dT(n) x G_prop
VT_integ(n)=dT(n)×G_integ+VT_integ(n−1)
+I(n)×α
Further, Tb(n) is the estimated value of the internal temperature of the rechargeable battery, and dT(n) is the difference between the detected external temperature value detected by the temperature detection unit and the past estimated value of the internal temperature. α is the first coefficient related to the heat generation amount, G_prop is the second coefficient of the proportional calculation, G_integ is the third coefficient of the integral calculation, and I(n) is the current detected by the current detection unit. is the current detection value,
The rechargeable battery temperature estimating device according to claim 5, characterized in that: The output means estimates and outputs the temperature of the rechargeable battery mounted on the vehicle, and the processor included in the vehicle estimates the operating state of the vehicle based on the estimated temperature value output from the output means. 9. The rechargeable battery temperature estimating device according to any one of claims 1 to 8, wherein the temperature is changed. In a rechargeable battery temperature estimation method for estimating the internal temperature of a rechargeable battery,
a calculating step of calculating the internal temperature based on a relational expression representing a relationship between at least one of a current flowing through the rechargeable battery and an external temperature of the rechargeable battery and the internal temperature of the rechargeable battery;
a fluid volume estimation step of estimating the fluid volume of the rechargeable battery;
a correction step of correcting the coefficient of the relational expression based on the liquid amount estimated in the liquid amount estimation step;
an output step of outputting the internal temperature calculated in the calculating step based on the relational expression whose coefficient is corrected by the correcting step;
A method for estimating temperature of a rechargeable battery, comprising: In a rechargeable battery temperature estimating device for estimating the internal temperature of a rechargeable battery,
a processor;
a memory storing a plurality of executable instructions that, when read and executed by the processor, perform the following actions:
calculating the internal temperature based on a relational expression showing the relationship between at least one of the current flowing through the rechargeable battery and the external temperature of the rechargeable battery and the internal temperature of the rechargeable battery;
estimating the fluid level of the rechargeable battery;
Correcting the coefficient of the relational expression based on the estimated liquid volume,
outputting the internal temperature calculated based on the coefficient-corrected relational expression;
A rechargeable battery temperature estimating device characterized by:

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