JP2012192811A - Device and method for estimating secondary battery temperature - Google Patents

Abstract

PROBLEM TO BE SOLVED: To estimate an internal temperature of a secondary battery accurately regardless of an engine state.SOLUTION: This device 10 for estimating the internal temperature of the secondary battery mounted to a vehicle includes a CPU 10a (calculation means) for obtaining a temperature estimation value by executing proportion operation and integral operation with respect to a differential value between the temperature detection value detected by a temperature sensor 10f to detect an outer temperature of the secondary battery 1 and the past temperature estimation value, and a CPU 10a (changing means) for changing a proportional gain of the calculation means and an integral gain of the integral operation according to the vehicle state.

Description

  The present invention relates to a secondary battery temperature estimation device and a secondary battery temperature estimation method.

  2. Description of the Related Art In recent years, in automobiles and the like, the number of electric devices that operate with electric power stored in secondary batteries has increased, and devices related to driving safety such as electric steering and electric brakes are also used in secondary batteries. It is to be driven by. It is known that the characteristics of such a secondary battery change with temperature. For example, since the capacity of the battery decreases as the temperature decreases, the engine startability may decrease when the temperature is low. For this reason, it is necessary to know the temperature of the secondary battery in consideration of safety, but the secondary battery uses a highly acidic or strongly alkaline electrolytic solution having high corrosive properties. It is difficult to detect the internal temperature by installing a temperature sensor inside.

  Therefore, for example, as disclosed in Patent Document 1, the battery liquid temperature at the time when the engine was last stopped, the battery outer peripheral temperature at the time when the engine was started, and the time when the engine was stopped are started. By applying the elapsed time up to the point in time to the model equation, the battery fluid temperature initial value at the time the engine is started is calculated, and the battery fluid temperature is estimated based on this initial value to determine the internal temperature. A method of measuring indirectly is presented.

  In Patent Document 2, the previous estimation result is compared with the temperature detected by the temperature sensor used for the current estimation, and the estimation constant is set to a different value depending on whether the detected temperature has increased or decreased. A method of indirectly measuring the internal temperature by performing estimation using an estimation equation is proposed.

JP 2008-249459 A JP 2009-146754 A

  Incidentally, the technique disclosed in Patent Document 1 has a problem that the internal temperature cannot be estimated when the engine is stopped. Further, the technique disclosed in Patent Document 2 has a problem that if the estimation constant is changed based on the change in the detected temperature, the timing of the change is delayed and accurate estimation cannot be performed.

  Accordingly, an object of the present invention is to provide a secondary battery temperature estimation device and a secondary battery temperature estimation method capable of accurately estimating the internal temperature of the secondary battery regardless of the state of the engine.

In order to solve the above-described problems, the present invention provides a secondary battery temperature estimation device that estimates an internal temperature of a secondary battery mounted on a vehicle, and a temperature detected by a temperature sensor that detects an external temperature of the secondary battery. A calculation means for obtaining a temperature estimated value by performing a proportional calculation and an integral calculation on a difference value between a detected value and a past temperature estimated value; a proportional gain of the proportional calculation of the calculation means; and an integral of the integral calculation Changing means for changing the gain according to the state of the vehicle.
According to such a configuration, the internal temperature of the secondary battery can be accurately estimated regardless of the state of the engine.

In addition to the above invention, another invention is characterized in that the changing means changes the proportional gain and the integral gain depending on whether or not the motor of the vehicle is in an operating state.
According to such a configuration, the internal temperature of the secondary battery can be accurately determined by changing the proportional gain and the integral gain depending on whether or not the prime mover that generates a large amount of heat is in an operating state.

According to another aspect of the invention, in addition to the above-described invention, the changing means sets a first proportional gain and a first integral gain as the proportional gain and the integral gain when the prime mover of the vehicle is in an operating state. When the prime mover is in a stopped state, a second proportional gain and a second integral gain that are smaller than the first proportional gain and the first integral gain are set.
According to such a configuration, the internal temperature of the secondary battery can be estimated more accurately by using two types of proportional and integral gains.

In addition to the above invention, another invention is characterized in that the changing means detects whether or not the prime mover is in an operating state by a position of an ignition key.
According to such a configuration, the state of the prime mover can be easily known from the position of the ignition key.

In addition to the above-mentioned invention, another invention is characterized in that the changing means detects whether or not the prime mover is in an operating state based on a magnitude of a current flowing through the secondary battery or a vehicle voltage.
According to such a configuration, the state of the prime mover can be easily known based on the current or voltage.

In another invention, in addition to the above-mentioned invention, the calculation means obtains the temperature estimated value based on the following equation: 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)
Tb (n) is an estimated temperature value, dT (n) is a difference value between the detected temperature value detected by the temperature sensor and a past estimated temperature value, G_prop is a proportional gain, and G_integ is an integral gain. Features.
According to such a configuration, the internal temperature of the secondary battery can be accurately estimated based on the above-described equation.

Further, the present invention provides a method for estimating the internal temperature of a secondary battery mounted on a vehicle, and a temperature detection value detected by a temperature sensor that detects an external temperature of the secondary battery, A calculation step for obtaining a temperature estimated value by performing a proportional calculation and an integral calculation on a difference value from the temperature estimated value, and the proportional gain of the proportional calculation and the integral gain of the integral calculation in the calculation step are set to a vehicle state. And a changing step that changes in response.
According to such a method, the internal temperature of the secondary battery can be accurately estimated regardless of the state of the engine.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the secondary battery temperature estimation apparatus and secondary battery temperature estimation method which can estimate the internal temperature of a secondary battery correctly irrespective of the state of an engine.

It is a perspective view which shows the structural example of the secondary battery temperature estimation apparatus which concerns on embodiment of this invention. It is a block diagram which shows the detailed structural example of the secondary battery temperature estimation apparatus shown in FIG. It is a block diagram which shows the algorithm implement | achieved when the program shown in FIG. 2 is performed. It is a figure which shows an example of the proportional gain and integral gain which are set to the constant multiplication circuit shown in FIG. It is a figure which shows the measurement result when a proportional gain and an integral gain are fixed. It is a figure which shows the actual measurement result in the case of changing a proportional gain and an integral gain. It is a flowchart for demonstrating operation | movement of this embodiment. It is a figure which shows the measurement result in the case of using a secondary battery with a large capacity | capacitance, without changing a proportional gain and an integral gain. It is a figure which shows the actual measurement result in the case of using a secondary battery with a large capacity | capacitance while changing a proportional gain and an integral gain.

  Next, an embodiment of the present invention will be described.

(A) Description of Configuration of Embodiment FIG. 1 is a perspective view showing an external configuration of a secondary battery temperature estimation device 10 according to an embodiment of the present invention. In this figure, a secondary battery temperature estimation device 10 is fixed to a connection terminal 4 connected to one terminal 3 of two terminals 2 and 3 of a secondary battery 1 by screws 5. Further, the secondary battery temperature estimation device 10 is connected to an ECU (Engine Control Unit) (not shown) or the like by a connection connector 12 and a connection cable 13, for example, inputs information related to the state of an ignition key or an estimated secondary battery. Or output information about the temperature of 1.

  The secondary battery 1 is composed of, for example, a lead storage battery, a nickel cadmium battery, a nickel hydride battery, or a lithium ion battery, and is charged by an alternator to drive a starter motor to start an engine that is a prime mover.

  FIG. 2 is a block diagram illustrating an electrical configuration example of the secondary battery temperature estimation device 10 illustrated in FIG. 1. As shown in this figure, the secondary battery temperature estimation device 10 includes a CPU (Central Processing Unit) 10a, a ROM (Read Only Memory) 10b, a RAM (Random Access Memory) 10c, a communication unit 10d, and an I / F (Interface). 10e, a temperature sensor 10f, a voltage sensor 10g, and a current sensor 10h. Here, the CPU 10a controls each unit 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. The RAM 10c is configured by a semiconductor memory or the like, and stores data generated when the program ba is executed, and a parameter 10ca such as a table or a mathematical expression described later. The communication unit 10d exchanges information with an ECU (not shown). The I / F 10e converts the signals supplied from the temperature sensor 10f, the voltage sensor 10g, and the current sensor 10h into digital signals and takes them in.

  The temperature sensor 10f is constituted by, for example, a thermistor or a thermocouple, and is disposed at a position close to the battery case of the secondary battery 1, detects the external temperature of the secondary battery 1, and uses the I / F 10e as a temperature detection signal. To the CPU 10a. In the present embodiment, “internal temperature” refers to the temperature of the electrolyte solution of the secondary battery 1. Further, the external temperature is a temperature outside the secondary battery 1, for example, an ambient temperature of the environment where the secondary battery 1 is arranged or a temperature of a resin constituting the battery case. Of course, as the external temperature, it is also possible to use the temperature of the terminals 2 and 3 itself, the ambient temperature, or the temperature in a liquid stopper not shown. Since the target for estimating the internal temperature is the electrolytic solution, the position where the temperature sensor 10f is provided is preferably, for example, in the vicinity of the portion of the battery case where the electrolytic solution is filled. Moreover, since the temperature of electrolyte solution is influenced by the heat from an engine so that it may mention later, as a position which attaches the temperature sensor 10f, it can be set as close as possible to an engine.

  The voltage sensor 10g detects the terminal voltage of the secondary battery 1, and supplies it as a voltage detection signal to the CPU 10a via the I / F 10e. The current sensor 10h detects the charging / discharging current of the secondary battery 1, and supplies it as a current detection signal to the CPU 10a via the I / F 10e. The I / F 10e converts the temperature detection signal, the voltage detection signal, and the current detection signal supplied from the temperature sensor 10f, the voltage sensor 10g, and the current sensor 10h into corresponding digital signals, and detects the temperature detection value, Captured as a voltage detection value and a current detection value.

  FIG. 3 is a block diagram showing a temperature estimation algorithm realized by executing the program 10ba shown in FIG. The block diagram shown in this figure has an addition / subtraction circuit 20, constant multiplication circuits 21 and 22, an integration circuit 23, an addition circuit 24, and a delay circuit 25. Here, the addition / subtraction circuit 20 subtracts the previous temperature estimated value Tb (n-1) output from the delay circuit 25 from the temperature detection value Ta (n) supplied from the temperature sensor 10f, and the obtained value. Is output as the difference value dT (n). Note that n indicates the number of processing times. The constant multiplication circuit 21 outputs a value obtained by multiplying the difference value dT (n) output from the addition / subtraction circuit 20 by a proportional gain G_prop. The constant multiplication circuit 22 outputs a value obtained by multiplying the difference value dT (n) output from the addition / subtraction circuit 20 by G_integ, which is an integral gain. The integration circuit 23 integrates and outputs the value output from the constant multiplication circuit 22. The adder circuit 24 adds the output value of the constant multiplication circuit 21 and the output value of the integration circuit 23, and outputs the obtained value as the estimated temperature value Tb (n). The delay circuit 25 delays the estimated temperature value Tb (n) output from the adder circuit 24 by one sample period, and outputs it to the adder / subtracter circuit 20 as Tb (n−1).

The above block diagram is expressed 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)
Also,
VT_integ (n) = dT (n) × G_integ + VT_integ (n−1)
... (3)

(B) Explanation of outline operation of embodiment Next, the outline of operation of this embodiment is explained. In the present embodiment, by executing the program 10ba shown in FIG. 2, the algorithm of the block diagram shown in FIG. 3 is realized, the temperature detection value output from the temperature sensor 10f is sampled at a predetermined period, and the proportional calculation is performed. And the temperature estimated value is output based on the integral calculation. The estimated temperature value thus obtained is supplied to an ECU (not shown), and the ECU executes processing such as temperature correction of the charging rate based on the supplied estimated temperature value.

  Here, in this embodiment, there are two types of proportional gain and integral gain of the constant multiplication circuits 21 and 22 shown in FIG. 3, as shown in FIG. Specifically, the first proportional gain and the first integral gain having a large value, and the second proportional gain and the second integral gain having a small value. These two types of gains are set according to the operating state of the vehicle. More specifically, when the engine that is the prime mover is in an operating state, the first proportional gain and the first integral gain are set in the constant multiplication circuits 21 and 22, and when the engine is in a stopped state, the second proportional gain is set. The second integral gain is set in the constant multipliers 21 and 22. Thus, the reason for changing the gain according to the state of the vehicle is that the tendency of the temperature change of the secondary battery 1 changes depending on the operation state of the vehicle, particularly the operation state of the prime mover. That is, the main cause of the temperature change of the secondary battery 1 is that heat generated by the operation of the prime mover is propagated to the secondary battery 1 by, for example, heat radiation, or by traveling wind or a radiator fan. This is because it is propagated to the secondary battery 1 by the generated wind. That is, the engine is disposed in the engine room where the secondary battery 1 is disposed, and the engine continues to generate a large amount of heat during the operation of the engine, so that the temperature rapidly increases. On the other hand, when the engine is stopped, the heat of the engine itself and the heat remaining in the engine room are cooled by natural cooling, so that the temperature gradually decreases. For this reason, since the rate of change in temperature differs between when the temperature rises and when the temperature falls, in this embodiment, the temperature is estimated separately.

  FIG. 5 is a diagram showing the results of temperature estimation in a state where the proportional gain and integral gain of the constant multiplication circuits 21 and 22 shown in FIG. 3 are fixed. In this figure, the horizontal axis indicates time and the vertical axis indicates temperature. Moreover, a continuous line is the measured value of the liquid temperature of the secondary battery 1, and the broken line has shown the estimated value of internal temperature. From the comparison of the solid line and the broken line, when the ignition key is on (when IG_ON (when the engine is operating)), the solid line and the broken line are approximately the same, so the temperature is estimated with relatively high accuracy. I understand that. On the other hand, when the ignition key is off (when IG_OFF (when the engine is stopped)), the solid line and the broken line are deviated from each other, indicating that the temperature estimation accuracy is not high.

  On the other hand, FIG. 6 is a diagram showing the results of temperature estimation when the proportional gain and integral gain of the constant multiplication circuits 21 and 22 shown in FIG. 3 are changed between when the ignition is on and when it is off. More specifically, when the ignition is on, the first proportional gain (= 0.1) and the first integral gain (= 0.015) shown in FIG. 4 are set, and when the ignition is off, the second proportional gain is set. (= 0.07) and the second integral gain (= 0.0005) are set. In FIG. 6, the solid line indicates the actual measured value of the liquid temperature of the secondary battery 1, and the broken line indicates the estimated value of the internal temperature. From the comparison of the solid line and the broken line, it can be seen that the temperature is estimated with high accuracy because the solid line and the broken line substantially coincide with each other both when the ignition key is on and when the ignition key is off.

  As described above, in the present embodiment, the temperature of the secondary battery 1 is estimated based on the proportional calculation and the integral calculation, and the proportional gain and the integral gain are changed according to the state of the vehicle. It becomes possible to estimate the internal temperature of the secondary battery 1 with high accuracy regardless of the state of the vehicle.

(C) Description of Detailed Operation of Embodiment Next, detailed operation of the present embodiment will be described. FIG. 7 is a flowchart for explaining processing for changing the proportional gain and integral gain of the block diagram shown in FIG. This flowchart is executed at predetermined intervals, for example. When the process shown in FIG. 7 is started, the following steps are executed.

In step S10, the CPU 10a detects the state of the vehicle. Here, the following states are detected as vehicle states.
(1) Ignition key on / off (2) Charge / discharge current magnitude of secondary battery 1 (3) Vehicle voltage magnitude Here, (1) is the engine that is the prime mover when the ignition key is on. Is in operation and can be determined to be stopped when it is off. As for (2), when the state where the charge / discharge current of the secondary battery 1 is a predetermined value (for example, several amperes) or more continues for a certain time (for example, 60 seconds), the prime mover is operating. Can be determined. For (3), the vehicle voltage (the generator voltage of the alternator or the terminal voltage of the secondary battery 1) is a predetermined value (for example, a voltage lower than the generator voltage of the alternator and higher than the fully charged voltage (for example, If a voltage of about 13.5 V)) continues for a certain time (for example, 60 seconds) or more, it can be determined that the engine is operating.

  In step S11, the CPU 10a determines whether or not the engine serving as the prime mover is operating based on the state of the vehicle detected in step S10. If it is determined that the engine is operating (step S11: Yes), the step is performed. The process proceeds to S12, and in other cases (step S11: No), the process proceeds to step S14. Specifically, when the ignition key is on, when the charge / discharge current of the secondary battery 1 continues for a predetermined time or more, or when the vehicle voltage continues for a predetermined time or more If so, the process proceeds to step S12. Otherwise, the process proceeds to step S14.

  In step S12, the CPU 10a acquires the first proportional gain shown in FIG. 4 from the parameter 10ca stored in the RAM 10c, and sets it in the constant multiplication circuit 21 shown in FIG.

  In step S13, the CPU 10a acquires the first integral gain shown in FIG. 4 from the parameter 10ca stored in the RAM 10c, and sets it in the constant multiplication circuit 22 shown in FIG.

  In step S14, the CPU 10a acquires the second proportional gain shown in FIG. 4 from the parameter 10ca stored in the RAM 10c, and sets it in the constant multiplication circuit 21 shown in FIG.

  In step S15, the CPU 10a acquires the second integral gain shown in FIG. 4 from the parameter 10ca stored in the RAM 10c, and sets it in the constant multiplication circuit 22 shown in FIG.

  With the above processing, the proportional gain and integral gain set in the constant multiplication circuits 21 and 22 can be changed based on the operation state of the vehicle. Note that if the proportional gain and the integral gain are suddenly changed, the proportional gain and the integral gain can be gradually changed in order to prevent the output from becoming unstable.

(D) Description of Modified Embodiment The above embodiment is an example, and it is needless to say that the present invention is not limited to the case described above. For example, the values of the proportional gain and the integral gain shown in FIG. 4 are examples, and the present invention is not limited only to such a case. For example, it is desirable to appropriately set the proportional gain and the integral gain depending on the type (for example, capacity) of the secondary battery 1 or the type of vehicle. This will be described in more detail. FIG. 8 shows a result in which 80D26 for cold district is mounted on a vehicle whose standard designated size of the secondary battery 1 is 55D23, and the temperature is estimated by the proportional gain and integral gain obtained for the standard designated size 55D23. FIG. In the example of FIG. 8, the solid line that is the actually measured value and the broken line that is the estimated value are greatly different both during engine operation and when the engine is stopped. On the other hand, FIG. 9 is a diagram comparing measured values and estimated values when using proportional gains and integral gains whose values are adjusted for 80D26 (for example, values are adjusted in proportion to weight). In the example of FIG. 9, as compared with the case of FIG. 8, the divergence between the solid line and the broken line is reduced, and the solid line and the broken line substantially match. Thus, it is desirable to set appropriate values for the proportional gain and the integral gain according to the type of the secondary battery 1, the type of the vehicle, the use environment, or the like.

  Moreover, the external appearance of the secondary battery temperature estimation apparatus 10 shown in FIG. 1 and the mounting method to the secondary battery 1 are examples, and this embodiment is not limited only to such a case. For example, as long as it is in the vicinity of the battery case of the secondary battery 1, it may be a place away from the terminals 2 and 3. Alternatively, only the temperature sensor 10f may be disposed in the vicinity of the secondary battery 1, and the other components may be disposed in a portion away from the secondary battery 1.

  In the above embodiment, as shown in FIG. 2, the CPU 10a or the like is used. However, in addition to this, for example, a DSP (Digital Signal Processor) or the like may be used. It may be configured by a circuit.

  Further, in the above embodiment, the determination is made based on the state of the ignition key, the magnitude of the charge / discharge current of the secondary battery 1, and the magnitude of the vehicle voltage. However, based on other information or the like, It is also possible to determine the state. For example, it may be determined that the engine is stopped when the rotation is 0 using a measurement signal of the engine tachometer (tachometer), and otherwise the engine is determined to be operating.

  In the above embodiments, the prime mover has been described assuming that a heat engine such as a reciprocating engine or a rotary engine is used. However, for example, when a motor such as a motor or a fuel cell is used as the prime mover. Needless to say, the present invention is applicable. That is, since these also generate heat during operation, the present invention can be applied to an electric vehicle that is a vehicle using these.

  In the above embodiment, as the operation state of the vehicle, the proportional gain and the integral gain are changed for whether or not the engine is operating. For example, in addition to these, based on the outside air temperature of the vehicle Thus, the proportional gain and the integral gain may be changed. That is, since the engine is naturally cooled after the engine is stopped, the temperature change of the secondary battery 1 in that case is affected by the outside air temperature.

DESCRIPTION OF SYMBOLS 1 Secondary battery 10 Secondary battery temperature estimation apparatus 10a CPU (calculation means, change means)
10b ROM
10c RAM
10d Communication unit 10e I / F
10f Temperature sensor 10g Voltage sensor 10h Current sensor

Claims (7)

In a secondary battery temperature estimation device that estimates the internal temperature of a secondary battery mounted on a vehicle,
A calculation means for obtaining a temperature estimated value by performing a proportional calculation and an integral calculation on a difference value between a temperature detection value detected by a temperature sensor that detects an external temperature of the secondary battery and a past temperature estimated value;
Changing means for changing the proportional gain of the proportional calculation and the integral gain of the integral calculation according to the state of the vehicle;
A secondary battery temperature estimation device comprising:   The secondary battery temperature estimation device according to claim 1, wherein the changing unit changes the proportional gain and the integral gain depending on whether or not the prime mover of the vehicle is in an operating state.   The changing means sets a first proportional gain and a first integral gain as the proportional gain and the integral gain when the prime mover of the vehicle is in an operating state, and when the prime mover is in a stopped state, 3. The secondary battery temperature estimation device according to claim 2, wherein a second proportional gain and a second integral gain that are smaller than the first proportional gain and the first integral gain are set.   4. The secondary battery temperature estimation apparatus according to claim 2, wherein the changing unit detects whether or not the prime mover is in an operating state based on a position of an ignition key.   5. The secondary according to claim 2, wherein the changing unit detects whether or not the prime mover is in an operating state based on a current flowing in the secondary battery or a magnitude of a vehicle voltage. 6. Battery temperature estimation device. The calculation means obtains the temperature estimated value based on the following equation:
Tb (n) = VT_prop (n) + VT_integ (n)
here,
VT_prop (n) = dT (n) × G_prop
VT_integ (n) = dT (n) × G_integ + VT_integ (n−1)
Tb (n) is an estimated temperature value, dT (n) is a difference value between the detected temperature value detected by the temperature sensor and a past estimated temperature value, G_prop is a proportional gain, and G_integ is an integral gain.
The secondary battery temperature estimation device according to any one of claims 1 to 5, wherein In a secondary battery temperature estimation method for estimating the internal temperature of a secondary battery mounted on a vehicle,
A calculation step of obtaining a temperature estimated value by performing a proportional calculation and an integral calculation on a difference value between a temperature detection value detected by a temperature sensor that detects an external temperature of the secondary battery and a past temperature estimated value;
A change step of changing the proportional gain of the proportional calculation and the integral gain of the integral calculation in the calculation step according to the state of the vehicle;
A secondary battery temperature estimation method comprising:

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