JP2003227865A - Method and apparatus for estimation of deterioration of battery as well as method and apparatus for warning of deterioration of battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for estimation of deterioration of a battery in which the deterioration of the battery can be estimated and warned by keeping an on-vehicle state, and to provide an estimation apparatus for estimation of the deterioration of the battery as well as to provide a method for warning the deterioration of the battery, and to provide a warning apparatus for the deterioration of the battery. <P>SOLUTION: During a period in which a value of a rush current flowing to a load at a start of the load is increased, a discharge current and a terminal voltage are measured periodically by a current and voltage measuring means 23a-1. A computing means 23a-2 removes from acquired data data containing a drop portion of the terminal voltage generated in an initial period of a discharge due to a charging polarization and a gassing, and it calculates an approximate quadratic expression of a discharge current-terminal voltage characteristic corresponding to the remaining data. An estimation means 23a-3 decides whether a quadratic term coefficient of the calculated approximate quadratic expression is positive or negative. When the coefficient is a negative value, it is estimated that the deterioration of the battery is in progress. When the estimation that the deterioration of the battery is in progress is continued in a prescribed number of times or more or when the estimation is performed at prescribed frequencies or more, a warning means 23a-4 warns the deterioration of the battery. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery deterioration estimating method and apparatus for estimating deterioration of a battery for supplying electric power to a load, and a battery deterioration warning method using the deterioration estimation. The present invention relates to a deterioration warning method and device.

[0002]

2. Description of the Related Art It is important to grasp the replacement time due to deterioration of a battery to some extent in order to use a mounted device such as a vehicle that uses a battery as a power source. The deterioration of the battery is closely related to the decrease of the dischargeable capacity, so if the deterioration of the battery is left unattended, the battery has enough dischargeable capacity to withstand the high current discharge for restarting the engine. However, once the engine is stopped, it may not be possible to restart it next time.

An electric capacity test is generally known as a method of knowing the deterioration of a battery from a decrease in the dischargeable capacity of the battery. In this method, the dischargeable capacity when the battery is fully charged is from a rated value to a certain level. It is presumed that it deteriorated when it fell below.

[0004]

However, in this electrical capacity test, the battery is once removed from the device to be mounted and charged to a fully charged state, and then the battery is completely discharged to measure the amount of discharged electricity. Therefore, it is difficult to say that it is a method that can be easily estimated because it requires a charge to a fully charged state, a complete discharge for measurement, a recharge for reusing the battery, and a test for a long time.

Therefore, the present invention has been made in view of the above circumstances, and provides a battery deterioration estimating method and device capable of easily estimating the deterioration of a battery while the battery is being used without removing the battery. The purpose is to do.

It is another object of the present invention to provide a battery deterioration warning method and device capable of estimating the deterioration of a battery during use without removing the battery and warning the deterioration.

[0007]

The invention according to claim 1 made in order to solve the above-mentioned problems, is the discharge current of the battery and the discharge current during the monotonically increasing period of the inrush current flowing through the load at the time of starting the load. Is periodically measured, and the measured discharge current and terminal voltage are collected as a data pair, and the terminal voltage generated at the initial stage of discharge due to elimination of charge polarization and gassing from the collected data pair. An approximate quadratic expression of the discharge current-terminal voltage characteristics corresponding to the remaining data pairs is calculated except for the data pair including the drop, and the coefficient of the quadratic term of the calculated approximate quadratic expression becomes a negative value. That is, the battery deterioration estimation method is characterized by detecting that the deterioration of the battery is progressing by the detection.

The above-mentioned invention according to claim 1 is found at the initial stage of discharge from the data pair collected to obtain the discharge current-terminal voltage characteristic during the monotonically increasing period of the inrush current flowing when the load starts. When the approximate quadratic equation was calculated using the remaining part where the data affected by the sudden voltage drop caused by the elimination of polarization and gassing was deleted, the deterioration progressed to the extent that the replacement time was approached. It was made paying attention to the finding that the quadratic term of the approximate quadratic equation tends to be negative in the existing battery. According to the procedure of claim 1, the discharge current of the battery and the terminal voltage corresponding to this discharge current are periodically measured during a monotonically increasing period of the rush current flowing through the load when the load is started, and the measured data is paired as a data pair. From the collected data pairs, except for the data pairs including the terminal voltage drop that occurs at the initial stage of discharge due to the elimination of charge polarization and gassing, an approximate second-order discharge current-terminal voltage characteristic corresponding to the remaining data pairs is collected. The equation is calculated, and it is estimated that the coefficient of the quadratic term of the calculated approximate quadratic equation becomes a negative value, and it is estimated that the deterioration of the battery is progressing by this detection.

Therefore, each time the load is activated and an inrush current flows, the approximate quadratic expression of the discharge current-terminal voltage characteristic calculated based on the measured discharge current of the battery and the terminal voltage is used. Since it can be estimated that the deterioration is progressing, it can be estimated that the deterioration of the battery is progressing even if the battery is in use without being removed.

In order to solve the above-mentioned problems, the invention of claim 2 is the method of estimating deterioration of a battery according to claim 1, wherein a predetermined number of data pairs are sequentially arranged from the one having a larger discharge current of the collected data pairs. The approximate quadratic expression is obtained by using the least squares method each time the increase is made, and the correlation coefficient between the obtained approximate quadratic equation and the data pair used in obtaining the approximate quadratic equation is obtained, and the obtained phase is obtained. A battery characterized in that the data pair until the relation number becomes smaller than a predetermined value is the remaining data pair except for the data pair including the drop of the terminal voltage that occurs at the initial stage of discharge due to elimination of charge polarization and gassing. It is in the deterioration estimation method.

According to the second aspect of the present invention, the remaining data pairs excluding the data pairs including the terminal voltage drop generated at the initial stage of discharge due to elimination of charge polarization and gassing,
A predetermined number of data pairs are sequentially increased from the larger discharge current of the collected data pairs, and an approximate quadratic equation is obtained by using the least squares method each time the discharge current is increased, and the obtained approximate quadratic equation and the approximate quadratic equation are obtained. The correlation coefficient with the data pair used for the calculation is obtained, and the data pair until the calculated correlation coefficient becomes smaller than the predetermined value is used.Therefore, the terminal voltage generated at the initial stage of discharge due to elimination of charge polarization and gassing. Of the discharge current-terminal voltage characteristics corresponding to the data pair that does not include the voltage drop
The following formula can be calculated.

In order to solve the above-mentioned problems, the invention of claim 3 is based on the method of estimating deterioration of battery according to claim 1 or 2, and it is estimated that the deterioration of the battery is progressing a predetermined number of times or more. A battery deterioration warning method is characterized in that the battery deterioration warning is performed when the battery is discharged or when the battery is discharged at a predetermined frequency or more.

According to the procedure of claim 3, it is estimated that the deterioration of the battery is in progress by the battery deterioration estimation method according to claim 1 or 2 for a predetermined number of times or more, or When it is done more than a predetermined frequency, it warns that the deterioration of the battery is progressing enough to replace it, so it is clear that it is necessary to replace it a predetermined number of times or a predetermined frequency until it seems that it is about to be replaced. By setting so as to match the time when the deterioration of the battery is progressing, it is possible to warn that the replacement time is approaching.

In order to solve the above-mentioned problems, the invention according to claim 4 is, as shown in the basic configuration diagram of FIG. 1, during the monotonous increase period of the inrush current flowing through the load at the time of starting the load,
A current-voltage measuring unit 23a-1 that periodically measures a discharge current of a battery and a terminal voltage corresponding to the discharge current, and a discharge current and a terminal voltage measured by the current-voltage measuring unit are collected and accumulated as a data pair. Storage means 23b,
From the data pairs collected and stored in the storage means, except for the data pairs including the drop of the terminal voltage that occurs at the initial stage of discharge due to the elimination of charge polarization and gassing, the remaining discharge current-terminal voltage corresponding to the data pair. The calculating means 23a-2 for calculating the approximate quadratic equation of the characteristic and the fact that the coefficient of the quadratic term of the approximate quadratic equation calculated by the calculating means has become negative, and the deterioration of the battery progresses by the detection. And a deterioration estimating means 23a-3 for estimating that the deterioration estimating device 23a-3 is included.

According to the configuration of the invention described in claim 4, the discharge current of the battery and the terminal voltage corresponding to the discharge current are measured by current-voltage measurement during the monotonically increasing period of the inrush current flowing through the load when the load is started. The means 23a-1 periodically measures and the storage means 23b collects and stores the measured discharge current and terminal voltage as a data pair. Computing means 23a
-2 is the discharge current-terminal voltage corresponding to the remaining data pairs, excluding the data pairs containing the drop of the terminal voltage that occurs at the initial stage of discharge due to the elimination of charge polarization and gassing from the collected and accumulated data pairs. An approximate quadratic equation of characteristics is calculated. The estimating means 23a-3 uses the calculated approximate quadratic equation of 2
It is estimated whether the coefficient of the next item is a negative value, and when it is a negative value, it is estimated that the deterioration of the battery is progressing.

Therefore, every time the load is activated and an inrush current flows, the approximate quadratic equation of the discharge current-terminal voltage characteristic calculated based on the measured discharge current of the battery and the terminal voltage is used. Since it can be estimated that the deterioration is progressing, it can be estimated that the deterioration of the battery is progressing even if the battery is in use without being removed.

According to a fifth aspect of the present invention, as shown in the basic configuration diagram of FIG. 1, the battery deterioration estimating apparatus according to the fourth aspect estimates that the deterioration of the battery is progressing a predetermined number of times or more. Warning means 23a that warns of the deterioration of the battery when it is done or when it is done more than a predetermined frequency.
-4 in the battery deterioration warning device.

According to the configuration of the invention described in claim 5, the battery deterioration estimation device according to claim 4 estimates that the deterioration of the battery is progressing a predetermined number of times or more, or When it is performed at a predetermined frequency or more, the warning means 23a-4 can warn of the deterioration of the battery, so that the deterioration of the battery is clearly progressed at a predetermined number of times or a predetermined frequency to the extent that it is considered that replacement is necessary. It is possible to warn that the replacement time is approaching by setting the time so that the replacement time matches.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION A battery deterioration estimating method and a warning method according to the present invention will be described below with reference to FIG. 2 showing a battery deterioration estimating apparatus and a warning apparatus for implementing these methods. In addition, the discharge current-terminal voltage characteristics during use of the battery are examined, and the discharge current-terminal voltage characteristics obtained by performing a specific process on the battery which is the basis of the idea of the present invention and whose deterioration is progressing. The process leading up to the discovery that the quadratic term of the approximate quadratic equation of (3) tends to be negative will be described below.

As a method for easily estimating the deterioration of a battery in a vehicle, which is in use, in the case of a gasoline engine vehicle, a specific load such as a starter motor, that is, an inrush current flowing when the load starts is measured. Then, approximation of discharge current-terminal voltage characteristics obtained from measurement data 2
A method of estimating the deterioration of the battery by calculating a parameter indicating the state of the battery such as an open circuit voltage and a pure resistance based on the following equation is considered.

The inrush current is characterized in that it has a property of rapidly increasing to a peak value which is several times the steady value or more in a short time and then rapidly decreasing to a steady value in a short time. , The maximum value corresponding to the expected peak value is different from the steady value corresponding to the current value when the load is in a driving state after the rush current flow has ended, but other loads than the starter motor Also in this case, a current having a substantially similar waveform may flow.

Most of the methods for obtaining the above-mentioned parameters are that the battery is in an equilibrium state, that is, there is no concentration polarization or activation polarization in the battery electrolyte and no voltage drop due to these components appears in the terminal voltage. It is implemented on the premise of. Therefore, an approximated curve is obtained from the data when the load is activated after a long time, for example, 24 hours, in which the polarization is eliminated after the use of the vehicle is stopped, and the usage state is limited. It was carried out only under conditions. This is because, as described above, even if the inrush current flows, the data of the discharge current and the terminal voltage obtained from the battery that is not in the equilibrium state at that time includes the influence of the polarization component before the inrush current flows. From such data, only an approximate quadratic equation of the discharge current-terminal voltage characteristic that changes depending on the remaining state of polarization can be obtained, and a meaningful approximate quadratic equation cannot be obtained by making a judgment based on a certain criterion.

In general, a gasoline vehicle supplies electric power to almost all electric loads during traveling from an alternator, and the surplus electric power is used for charging a battery. Batteries are often charged up to near full charge. Therefore, the charge polarization generated during charging remains in the battery immediately after being charged to near the fully charged state. From such a battery, when the starter motor is started to start the engine, only an approximate quadratic expression of the discharge current-terminal voltage characteristic including the influence of charge polarization can be obtained. In particular, at the time of discharging immediately after being charged to a fully charged state, a gassing reaction accompanied by the generation of gas during charging occurs, so it is known that the effect of eliminating gassing that gas generated during charging disappears also appears. .

On the other hand, in the case of a hybrid vehicle, the battery is frequently charged and discharged, and the motor generator, which can be regarded as a load and functions as an assisting motor or a cell motor, is also frequently activated. , While driving, until the motor generator is started,
The battery may not be fully charged, but is charged to 80% or more.

By the way, the gassing reaction appears in a battery in a state of charge of 80% or more, a short time after the start of charging, and then rapidly increases the terminal voltage of the battery. Due to this gassing reaction, the terminal voltage of the battery becomes much higher than the terminal voltage (open circuit voltage) in the equilibrium state.

The rise in the terminal voltage due to the gassing reaction remains for a while even after the charging current is stopped similarly to the charging polarization, and when the discharge is started from this state, the gassing reaction and the charge occur at the initial stage of the discharge. A sharp voltage drop is seen due to the elimination of polarization.

Therefore, it is considered that an approximate quadratic equation of the discharge current-terminal voltage characteristic that does not include the influence of the polarization component before the inrush current flows at the time of starting the load can be obtained, and the charge level at which a gassing reaction occurs A battery is charged up to and a pseudo inrush current similar to the inrush current that flows when a specific load such as a starter motor or motor generator is started is sent using an electronic load. And the data pair obtained by measuring the terminal voltage corresponding to this, except for the data that is considered to include the influence of elimination of the charging polarization and the gassing reaction, the discharge current-terminal voltage characteristics were obtained from the remaining data. I saw it.

Further, in order to examine how the obtained discharge current-terminal voltage characteristics are changed depending on the state of the battery, the charging time is made the same for the batteries of the same type but in various states. During a monotonically increasing period of the pseudo rush current flowing in the electronic load, the discharge current of the battery and the terminal voltage corresponding to the discharge current are periodically measured, and the measured discharge current and terminal voltage are collected as a data pair, From the collected data pairs, except for the data pairs including the drop of the terminal voltage that occurs at the initial stage of discharge due to elimination of charge polarization and gassing, an approximate quadratic expression of discharge current-terminal voltage characteristics corresponding to the remaining data pairs. Was calculated and viewed.

A comparative examination of approximate quadratic equations of discharge current-terminal voltage characteristics calculated for batteries of the same type but in various states shows that deterioration progresses to some extent even if replacement is not necessary. It was discovered that the sign of the quadratic term of the approximated quadratic equation is negative for the battery that has a quadrature.

Below, the data pairs actually obtained for the three sample batteries NO1 to NO3 are excluded before and after the data pair including the terminal voltage drop that occurs at the initial stage of discharge due to elimination of charge polarization and gassing is removed. Corresponding discharge current-terminal voltage characteristics will be described in detail with reference to the graphs of FIGS. 3 to 8 together with the approximation quadratic equation of the characteristics.

Three sample batteries NO1 to NO3
About these, OCV (open circuit voltage which is the terminal voltage of the battery in the equilibrium state) at the time of full charge, capacity at full charge when charged from 0% capacity to full charge, and discharge from full charge to end-of-discharge voltage The complete discharge capacities are shown in the table below.

[0032]

[Table 1]

The OCV before the test was 12.18 V for sample NO1 and 12.2 V for sample NO2.
9V, and sample NO3 is 11.64V, and when all samples are in a state of charge of 80% or more of full charge, 14.1V at an ambient temperature of 25 ° C.
Constant voltage charging for 10 seconds, and immediately after that, using an electronic load, a triangular wave pulse discharge that increases from 0 to over 100 A per second and then decreases to 0 is performed. During the period when the discharge current increases, The discharge current and the terminal voltage are measured at a sampling period of 2 ms (milliseconds), and the data pairs of the discharge current and the terminal voltage are collected and accumulated, and these data pairs are plotted on a graph. The discharge current-terminal voltage characteristics as shown in FIG. An approximate quadratic equation of the discharge current-terminal voltage characteristic is also attached to each graph.

As is clear from the characteristic graphs of FIGS. 3 to 5, when the discharge current in the initial stage of discharge is small, the charge polarization generated during charging, which both cause the terminal voltage of the battery to rise, A sharp drop in the terminal voltage is appearing due to the elimination of gassing.

On the other hand, except for the data pairs including the sharp drop of the terminal voltage due to the elimination of the charge polarization and the gassing, only the remaining data pairs are plotted and the discharge current-terminal voltage characteristics corresponding to these data pairs are plotted. When determined, the graphs shown in FIGS. 6 to 8 were obtained as those corresponding to FIGS. 3 to 5. The graph also includes an approximate quadratic equation of the discharge current-terminal voltage characteristic.

Comparing the approximate quadratic expressions of the discharge current-terminal voltage characteristics shown in the graphs of FIGS. 6 to 8, in the battery of sample NO3, the terminal generated at the initial stage of discharge due to elimination of charge polarization and gassing. It can be seen that the sign of the quadratic term of the approximate quadratic expression of the discharge current-terminal voltage characteristics corresponding to the remaining data pairs excluding the data pair including the voltage drop is negative. As is clear from Table 1, the battery of sample NO3 has no difference from the batteries of sample NO1 and NO2 except that the battery is deteriorated. Then, the battery in which the coefficient of the quadratic term becomes negative is relatively deteriorated, and the battery of sample NO3 does not need to be replaced immediately, but it may be considered that the time for replacement is approaching. It is possible.

In reality, a battery in which the sign of the coefficient of the quadratic term of the approximate quadratic expression of the discharge current-terminal voltage characteristic becomes negative is always hereafter even if the sign of the coefficient of the quadratic term becomes negative. This state does not continue, and further progress of deterioration causes the state of becoming negative to continue or the frequency of becoming negative to increase. Therefore, it is necessary to experimentally determine in advance how often the battery becomes negative or how often it becomes negative so that the deterioration of the battery approaches the time of replacement. The fact that the sign of the coefficient of the quadratic term becomes negative as the deterioration progresses can be used to warn that it is time to replace.

Next, a method of calculating an approximate quadratic expression of the discharge current-terminal voltage characteristic corresponding to the remaining data pairs except for the data pairs including the sudden drop of the terminal voltage due to the elimination of charge polarization and gassing. Will be specifically described.

As described above, the discharge current and the terminal voltage of the battery are measured at the sampling period of 2 ms when discharged using the electronic load immediately after the constant voltage charging for 10 seconds, and are collected and stored as a data pair. After that, the data pairs are sequentially increased by a predetermined number in the direction from the larger current value to the smaller current value, and each time the number is increased, the approximate quadratic equation for the data pair is calculated using the least squares method. Then, each time the approximate quadratic expression is calculated, the correlation coefficient between the data pair used for calculating the approximate quadratic expression and the approximate quadratic expression is obtained. If the increased data pair contains a voltage drop due to elimination of charge polarization and gassing, the approximate quadratic equation is affected, and the value of the correlation coefficient between the data pair and the approximate quadratic equation becomes small. Become.

Therefore, each time the predetermined number of data pairs are increased, it is judged whether or not the correlation coefficient obtained is less than or equal to a predetermined value. When the correlation coefficient is less than or equal to the predetermined value, the voltage drop due to the elimination of charge polarization and gassing. There is a data pair that includes a minute, and the set of data pairs immediately before that is the remaining data pair that does not include the voltage drop due to elimination of charge polarization and gassing. Approximate 2 calculated up to this data pair The following equation can be an approximate quadratic equation of the discharge current-terminal voltage characteristics corresponding to the remaining data pairs, except for the data pairs including the terminal voltage drop that occurs at the initial stage of discharge due to elimination of charge polarization and gassing.

An embodiment of a battery deterioration estimating method according to the present invention made in view of the above-mentioned discoveries, and an embodiment of an apparatus for implementing the battery deterioration warning method using the estimation performed by the method will be described. The deterioration warning device will be described with reference to FIG.

In FIG. 2, the deterioration warning device of the present embodiment indicated by reference numeral 1 is mounted on a hybrid vehicle having a motor generator 5 in addition to the engine 3. And
In this hybrid vehicle, only the output of the engine 3 is normally transmitted from the drive shaft 7 to the wheels 11 via the differential case 9 to drive the hybrid vehicle, and when the load is high, the motor generator 5 functions as a motor by the electric power from the battery 13. Then, in addition to the output of the engine 3, the output of the motor generator 5 is transmitted from the drive shaft 7 to the wheels 11, and the assist travel is performed.

Further, this hybrid vehicle is configured to cause the motor generator 5 to function as a generator (generator) at the time of deceleration or braking, convert kinetic energy into electric energy and charge the battery 13.

The motor generator 5 is further used as a starter motor for forcibly rotating the flywheel of the engine 3 when the engine 3 is started when the starter switch (not shown) is turned on.

The deterioration warning device 1 of the present embodiment provides the discharge current of the battery 13 to the motor generator 5 or the like which functions as a motor for assisted travel or a starter motor, and the charging current to the battery 13 from the motor generator 5 which functions as a generator. Current sensor 15 for detection
And a voltage sensor 17 having an infinite resistance connected in parallel to the battery 13 and detecting the terminal voltage of the battery 13.

In the deterioration warning device 1 of this embodiment, the outputs of the current sensor 15 and the voltage sensor 17 described above are fetched after A / D conversion in the interface circuit (hereinafter abbreviated as “I / F”) 21. And a microcomputer (hereinafter abbreviated as “microcomputer”) 23. The microcomputer 23 includes a CPU 23a and a RAM 23.
b, a ROM 23c, a RAM 23b has a data area for storing various data and a work area used for various processing operations, and the ROM 23c has a CPU 23a.
A control program for causing various processing operations to be stored in is stored.

The current value and the voltage value output from the current sensor 15 and the voltage sensor 17 are sampled at a high speed in a short cycle and taken into the CPU 23a of the microcomputer 23 via the I / F 21 and taken in. The current value and the voltage value are collected in the data area (corresponding to a storage means) of the RAM 23b and used for various processes.

Next, the processing performed by the CPU 23a in accordance with the control program stored in the ROM 23c will be described with reference to the flowchart of FIG.

The CPU 23a is normally in the sleep mode in which the starter key switch (not shown) is operated with the minimum power consumption until it comes to the ACC or ON position. When the starter key switch (not shown) is in the ACC or ON position, it operates. To start the initialization process (step S1), and wait for the ignition switch (IG switch) to be turned on (step S2). When the ignition switch is turned on (YES in step S2
S), for example, the discharge current and the terminal voltage are measured in a cycle of 100 μS (microseconds), and data collection is started (step S
3).

In the process of collecting the actual data in step S3, the maximum value of the inrush current is detected by comparing the magnitude relationships of the collected actual data before and after (step S4). When the maximum value is detected CPU2
3a stops the measurement of the discharge current and the terminal voltage, and executes the approximate quadratic equation calculation routine for calculating the approximate quadratic equation of the discharge current-terminal voltage characteristic using the measured data pair (Yes in step S4).

By executing the approximate quadratic equation calculation routine in step S5, the CPU 23a removes the data pair including the abrupt terminal voltage drop due to the elimination of the gassing that occurs at the initial stage of discharge, and the data pair remaining is high. An approximate quadratic expression indicating the correlation value is calculated.

In step S6, the CPU 23a determines whether the coefficient of the quadratic term of the approximate quadratic expression calculated by the approximate quadratic expression calculating routine in step S5 is positive or negative. If the coefficient is positive, the battery has deteriorated. It is estimated that there is not, and the determination result is stored in the RAM 23.
After the latest determination result data is recorded in the predetermined area provided in b, the processing is terminated and the mode is shifted to the sleep mode (NO in step S6, and step S10). When it is determined that the coefficient of the quadratic term of the approximate quadratic equation is negative (YES in step S6), the CPU 23a estimates that the battery is deteriorated, and the determination result is stored in a predetermined area provided in the RAM 23b. After recording as the latest determination result data, the process proceeds to the previous process. (Step S7)

The predetermined area provided in the RAM 23b has a capacity for recording a predetermined number of judgment result data, and when the predetermined number of judgment result data is recorded in the predetermined area, the latest judgment result data is recorded. Prior to that, the oldest determination result data is deleted to record. Furthermore, when the battery is replaced according to the warning, all the determination result data are reset.

Whether the judgment result data recorded in a predetermined area provided in the RAM 23b is the predetermined number of times that the coefficient of the quadratic term of the approximate quadratic expression becomes negative in step S8. It is used to determine whether or not it became negative at a certain frequency or more.

When the number of times that the coefficient of the quadratic term of the approximate quadratic equation becomes negative is less than the predetermined number of times or when it is determined that the coefficient is less than the predetermined frequency, the CPU 23
In the case of a, the battery is still usable, and it is not necessary to give a warning for replacement, and the processing is terminated and the sleep mode is entered. (No in step S8)

When the coefficient of the quadratic term of the approximate quadratic expression becomes negative a predetermined number of times or more, or when it is determined that the coefficient of the quadratic term becomes negative at a predetermined frequency or more, the battery is replaced to the extent necessary. It is determined that the deterioration has progressed (step S
8), and after displaying a warning to the user to recommend replacement (step S9), the process ends and shifts to the sleep mode.

In the sleep mode, the data recorded in the RAM is always saved and backed up from the battery by a small current.

Further, the approximation 2 obtained in step S5
The coefficient of the quadratic term in the following equation is in the order of 10 -4 to 10 -7 in absolute value, and even a small measurement error immediately affects it, and the coefficient of the quadratic term that became negative once may become positive again. However, the magnitude of the coefficient cannot be meaningful. Therefore, although it can be estimated that the deterioration is progressing, it is difficult to make any judgment using this estimation itself. Therefore, after the deterioration progresses to such an extent that the coefficient of the quadratic term becomes negative, and to what extent the deterioration progresses to the extent that replacement is required, the estimated number of consecutive occurrences or the estimated occurrence frequency Is experimentally obtained in advance, and the obtained number of times or frequency is set as a predetermined value.
It is warned that the deterioration of the battery is advanced enough to be replaced by determining whether the deterioration estimation made in step S6 has continuously occurred a predetermined number of times or more or has occurred at a predetermined frequency or more. Will be able to.

As is clear from the description given with reference to the flowchart of FIG. 9, the CPU 23a responds to the discharge current of the battery and the discharge current during the monotonically increasing period of the rush current flowing to the load when the load is started. Current-voltage measuring means 23a-1 for periodically measuring the terminal voltage, RAM 23b
Among the data pairs collected and accumulated in a predetermined area, the data pair including the remaining data pair, except the data pair including the drop of the terminal voltage that occurs at the initial stage of discharge due to the elimination of charge polarization and gassing, is left The calculating means 23a-2 for calculating the approximate quadratic expression of the voltage characteristic, the calculated approximate quadratic expression 2
Deterioration estimating means 23a-3 for detecting that the coefficient of the next term becomes negative and estimating that the deterioration of the battery is progressing by the detection, whether the estimation is continuously performed a predetermined number of times or more, or a predetermined number of times. Each of them functions as a warning unit 23a-4 that warns the deterioration of the battery when the frequency is equal to or higher than the frequency.

In the above-described embodiment, it is determined whether the coefficient of the quadratic term has become negative for a predetermined number of times or more or the coefficient of the quadratic term has become negative for a predetermined number of times or more. Although it warns that deterioration is progressing and replacement is necessary, it is estimated that deterioration is progressing because the coefficient of the quadratic term becomes negative without using this on the vehicle. , Collect as one vehicle information together with other vehicle information, analyze by performing centralized processing in a place other than the vehicle based on the collected vehicle information, and analyze the battery status as one of the methods of managing many vehicles. It can also be used to judge.

[0061]

As described above, according to the invention of claim 1 or 4, it is obtained by measuring the discharge current and the terminal voltage of the battery when a specific load is activated and an inrush current flows. Since it is possible to estimate whether or not the battery deterioration is progressing only by processing the actual data, it is possible to estimate the deterioration of the battery when the battery is used under normal conditions, that is, even during use without removing the battery. An estimation method and device can be provided.

According to the second aspect of the present invention, the remaining data pairs excluding the data pair including the terminal voltage drop generated at the initial stage of discharge due to the elimination of charge polarization and gassing are:
A predetermined number of data pairs are sequentially increased from the larger discharge current of the collected data pairs, and an approximate quadratic equation is obtained by using the least squares method each time the discharge current is increased, and the obtained approximate quadratic equation and the approximate quadratic equation are obtained. The correlation coefficient with the data pair used for the calculation is calculated, and the data pair until the calculated correlation coefficient becomes smaller than a predetermined value is used, and the drop of the terminal voltage that occurs at the initial stage of discharge due to elimination of charge polarization and gassing. Since an approximate quadratic expression of the discharge current-terminal voltage characteristic corresponding to a data pair not including can be calculated, it is possible to provide a battery deterioration estimation method capable of estimating battery deterioration even during use without removing the battery.

According to the third or fifth aspect of the invention, the estimation of the deterioration of the battery according to the first or fourth aspect of the invention is performed a plurality of times determined in advance, so that the deterioration of the battery is required to be necessary. Since the warning is given by judging that the battery is proceeding, it is possible to provide a battery deterioration warning method and device capable of issuing a highly accurate warning when the battery needs to be replaced.

[Brief description of drawings]

FIG. 1 is a block diagram showing a basic configuration of a battery deterioration estimating device and a warning device of the present invention.

FIG. 2 is an explanatory diagram showing, in a partial block diagram, a schematic configuration of a battery deterioration estimation device and a warning device according to an embodiment of the present invention to which the battery deterioration estimation method and warning method of the present invention are applied.

FIG. 3 is a graph showing discharge current-terminal voltage characteristics of sample battery 1.

FIG. 4 is a graph showing discharge current-terminal voltage characteristics of sample battery 2.

FIG. 5 is a graph showing discharge current-terminal voltage characteristics of the sample battery 3.

6 is a graph showing the discharge current-terminal voltage characteristic graph of FIG. 3 except for the data pair including the terminal voltage drop generated at the initial stage of discharge due to the elimination of charge polarization and gassing, and the discharge current-terminal voltage corresponding to the remaining data pair; It is a graph which shows a characteristic.

7 is a graph corresponding to FIG. 4 and showing the same discharge current-terminal voltage characteristics as in FIG.

8 is a graph showing a discharge current-terminal voltage characteristic similar to FIG. 6 corresponding to FIG.

9 is a flowchart showing a process performed by a microphone computer in FIG. 2 according to a program.

[Explanation of symbols]

23a-1 Current-voltage measuring means (CPU) 23a-2 Computing means (CPU) 23a-3 Estimating means (CPU) 23a-4 Warning means (CPU) 23b Storage means (RAM)

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Enomoto Mitsuto             1500 Onjuku, Susono City, Shizuoka Prefecture Yazaki Corporation             Within (72) Inventor Yoichi Arai             1500 Onjuku, Susono City, Shizuoka Prefecture Yazaki Corporation             Within F-term (reference) 2G016 CA03 CB13 CB25 CC01 CC02                       CC03 CC04 CC06 CC07 CC16                       CC23 CC27 CC28 CE00 CF07                 5G003 BA01 EA08 GC05                 5H030 AA06 AS08 FF42 FF44

Claims (5)

[Claims] 1. A discharge current of a battery and a terminal voltage corresponding to the discharge current are periodically measured during a monotonically increasing period of an inrush current flowing through the load when the load is started, and the measured discharge current and terminal voltage are measured. From the collected data pairs, except for the data pair including the drop of the terminal voltage drop that occurs at the initial stage of discharge due to the elimination of charge polarization and gassing, and the remaining discharge current corresponding to the data pair. An approximate quadratic expression of the terminal voltage characteristic is calculated, it is detected that the coefficient of the quadratic term of the calculated approximate quadratic expression becomes a negative value, and it is estimated that the deterioration of the battery is progressing by the detection. A method for estimating deterioration of a battery, comprising: 2. The battery deterioration estimating method according to claim 1, wherein a predetermined number of data pairs are sequentially increased from the one having a larger discharge current of the collected data pairs, and each time the increase is performed, an approximation quadratic method is performed using a least square method. An equation is obtained, a correlation coefficient between the obtained approximate quadratic equation and the data pair used in obtaining the approximate quadratic equation is obtained, and data pairs until the obtained correlation coefficient becomes smaller than a predetermined value are calculated. Except for the data pair that includes the drop in terminal voltage that occurs at the beginning of discharge due to elimination of charge polarization and gassing,
A method of estimating deterioration of a battery, characterized in that the remaining data pairs are used. 3. The battery deterioration estimation method according to claim 1 or 2, wherein the deterioration of the battery is estimated to be progressing a predetermined number of times or more than a predetermined frequency. , A method for warning the deterioration of a battery, which warns of deterioration of the battery. 4. A current-voltage measuring means for periodically measuring a discharge current of a battery and a terminal voltage corresponding to the discharge current during a monotonically increasing period of an inrush current flowing through the load at the time of starting the load, and the current-voltage measuring means. The storage means for collecting and storing the discharge current and the terminal voltage measured by the measuring means as a data pair, and the terminal voltage generated at the initial stage of discharge due to elimination of charge polarization and gassing from the data pair collected and stored in the storage means. Computation means for calculating an approximate quadratic expression of the discharge current-terminal voltage characteristics corresponding to the remaining data pairs excluding the data pair including the drop, and a coefficient of the quadratic term of the approximate quadratic expression calculated by the arithmetic means. Deterioration estimating device for detecting that the battery has deteriorated and estimating that the deterioration of the battery is progressing by the detection. . 5. The battery deterioration estimating apparatus according to claim 4 estimates that the deterioration of the battery is progressing a predetermined number of times or more, or when the battery deterioration is estimated at a predetermined frequency or more. A battery deterioration warning device, comprising a warning means for warning the progress of the battery.