JP2003009406A - Rechargeable battery status calculator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To judge a degradation cause by understanding a usage environment condition in which a secondary battery has actually experienced before its degradation occurs. SOLUTION: Various conditions concerned with a secondary battery's performance are detected from a temperature detection means 18, a voltage detection means 16 and a current detection means 17. Experience time, experienced charge, discharge current volume, or condition detection count is integrated and stored in a storage means 15 through a computing means 14. By storing the information to judge a degradation condition of the secondary battery, variation in a usage environment is known to judge the degradation cause.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a state calculating device for a secondary battery used in a secondary battery such as a nickel hydrogen secondary battery and a lithium ion secondary battery, and more particularly to a secondary battery and a secondary battery. The present invention relates to a secondary battery state calculation device for storing a use state in a battery pack, which includes a battery protection circuit, a secondary battery state calculation circuit, and the like.

[0002]

2. Description of the Related Art A battery pack including a secondary battery and a secondary battery state calculation device (including a secondary battery protection circuit)
The secondary battery state calculation device provided in the battery pack is intended to prevent the safety and performance deterioration of the battery pack when it is charged / discharged and to store the usage condition. It's important.

The above-mentioned function realized as the safety / performance deterioration prevention function is realized by utilizing the voltage of the secondary battery, the charging or discharging current, the temperature information, and the integrated current amount in the charging or discharging. However, regarding temperature information, a method of measuring the temperature of the secondary battery surface and predicting the environmental temperature from the secondary battery surface temperature before and after charging and discharging, and a temperature other than the secondary battery surface temperature, that is, the purpose of measuring the environmental temperature. There is a method of separately providing a temperature detecting means to be used and calculating the state of the secondary battery separately from the temperature detected by the secondary battery surface temperature detecting means.

As safety and performance deterioration prevention, prevention of overcharged state due to voltage, prevention of overdischarged state, prevention of overdischarged current due to current, prevention of overcharged current, prevention of use outside operating temperature conditions due to temperature In addition, prevention of application of an excessive amount of charged electricity to the secondary battery block can be mentioned. Detection thresholds of various detection contents set according to the capabilities of various elements arranged in the secondary battery block and the charging / discharging current path constituting the battery pack are appropriately set.

When the secondary battery state calculation device detects the above-mentioned various safety / performance deterioration prevention states, it limits charging, discharging or charging / discharging to prevent safety / performance deterioration. At this time, when the communication means or the display means is configured in the battery pack, it is possible to show the reason why the battery pack prohibits the charging or discharging, but it is not stored in the storage device.

As an exceptional condition, when a state in which the battery pack is completely prohibited from charging / discharging is detected, the voltage / current / temperature and the reason for determining whether charging / discharging is prohibited are stored. There is also a secondary battery state calculation device having a specification stored in the means. In this case, the various contents stored in the storage means are stored as various information at the time when the state calculation device of the secondary battery determines the charge / discharge prohibited state.

Further, the function realized as the use state storage has a function called a cycle count for storing the number of times the secondary battery is charged or discharged.

However, the function of storing the number of times of charging or discharging, which is called a cycle count, is not a unified function as a clear specification, and various specifications are currently realized.

As a cycle counting function which is generally realized, a method of integrating a charging or discharging current amount and counting up a cycle count when a charging or discharging current amount exceeding a set current amount is integrated, a current A method of counting up the number of times the start of charging or discharging is detected has been realized regardless of the amount.

When the state calculating device for the secondary battery has a function of calculating the remaining capacity of the secondary battery block, the storage means stores the amount of electricity that the secondary battery block can discharge when fully charged in the storage means. . By storing the amount of electricity that can be continuously discharged when discharged from the fully charged state, the percentage display of the amount of electricity charged in the secondary battery that changes sequentially due to charging and discharging recognized by the state calculation device of the secondary battery Is possible,
It is possible to calculate the charge / discharge time until full charge or complete discharge by performing charge / discharge.

The amount of electricity stored in the above-mentioned storage means and which can be discharged at full charge is generally called a learning capacity. The learning capacity is the capacity value of the secondary battery block that is updated by the function that updates the amount of electricity that can be discharged when the secondary battery block is fully charged, which changes with the passage of time and usage conditions. It is set in the battery status calculator.

Generally, the learning capacity is updated with the amount of discharged electricity discharged from the fully charged state to the fully discharged state or the amount of charged electricity charged from the completely discharged state to the fully charged state. General setting conditions for capacity learning are:
For example, it is possible to continuously perform discharging from the state in which full charge is detected and not detect the charging current halfway until the preset discharge voltage value is detected.

When learning is carried out, the content stored in the storage means is only to store the capacity in which the secondary battery block has been discharged as the learning capacity. However, like nickel-metal hydride batteries, each physical change (dT / d
In the case of a battery system in which the amount of charged electricity charged by the time when (t, −dV, TCO, etc.) is detected is different for each physical change, the learning capacity is greatly different for each full charge determination means. At this time, not only the detected full charge determination method is stored in the storage means, but also calculation such as storing the learning capacity separately for each full charge determination method may be used.

[0014]

As described above, the contents stored in the storage means in the battery pack are necessary for determining the current state of the secondary battery block determined by the state calculating device for the secondary battery. However, it is not possible to determine what kind of experience the secondary battery block has experienced as a result of the current determination made by the secondary battery state calculation device. Further, regarding the cycle counting function described as the conventional technology, which can be considered as the only usage history, there is a problem that the meaning indicated by the number of cycles counted up cannot always be used as the usage history for determining the deterioration state of the secondary battery. is there. Since this is counted by the number of times charging and discharging are performed or the capacity regardless of the temperature, voltage, and charging / discharging current conditions that greatly affect the performance of the secondary battery, it can be used as an indicator of the state of deterioration of the secondary battery. Means not to be.

Further, regarding the safety / performance deterioration prevention function which may greatly affect the performance deterioration of the secondary battery, it is stored that the prevention function is operating in the prevention function operating state. Since no protection function is detected and how many times it is detected, it is practically impossible to verify what kind of abnormal use condition was previously used.

The present invention is intended to solve such a problem, and an object of the present invention is to store a use state history of a battery pack containing a rechargeable battery block by a rechargeable battery state computing device so that the use history is successively stored. It is to provide the function that can grasp.

[0017]

A battery pack incorporating a state-of-charge device for a secondary battery according to the present invention is connected to a battery block composed of one or a plurality of secondary battery cells, and the battery block is increased or decreased by charging and discharging. Is a state calculation device for a secondary battery that calculates and communicates or displays the amount of charged electricity of the battery block, and voltage detection means for monitoring various cell voltages constituting the battery block, and current for detecting charge / discharge current of the battery block. Detecting means, temperature detecting means for detecting the surface temperature of the battery block, calculating means for calculating the state of the battery block using electric signals obtained from the voltage detecting means and the current detecting means, and through the calculating means And a storage unit that stores various kinds of information, wherein the calculation unit is for each charge / discharge current with respect to the temperature state experienced by the battery block. As test time or discharge current amount,
The data is stored in the storage means.

Specifically, the number of times the battery block is fully charged is detected in the storage means, and the number of times the battery block is fully charged is detected in the storage means for each detection determination condition.
The number of detections of the over-discharge voltage set value set in the storage means in advance in the discharge state is stored, and the secondary battery before update can be discharged when fully charged when the amount of electricity that can be discharged when the secondary battery is fully charged is updated. The amount of electricity is stored in the storage means, the full-charge detection condition is stored in the storage means for each full-charge detection, and when the amount of electricity that can be discharged when the secondary battery is fully charged is updated, it is stored as a factor of the update value. The charging detection condition is stored, and the number of times the safety or performance deterioration prevention function is performed, which is determined by the state calculation device, is stored in the storage unit for each prevention function.

As a result, the usage history can be grasped by the secondary battery status calculation device sequentially storing the usage status history of the battery pack containing the secondary battery block.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic block diagram of a battery pack having a state calculating device for a secondary battery according to an embodiment of the present invention.

The secondary battery block 13 is a battery pack 11
And a secondary battery state calculation device 12 is provided in the battery pack 11. Secondary battery block 13
Allows the power supply to the outside through the charge / discharge terminals 1a and 1b of the battery pack 11.

The secondary battery state calculation device 12 includes a storage means 15 for temporarily storing set values for various controls and the state of the secondary battery block 13, and a voltage for measuring various voltages of the secondary battery block 13. Detecting means 16, secondary battery block 1
The current detecting means 17 for detecting the charging / discharging current of No. 3, the temperature detecting means 18 for detecting the surface temperature of the secondary battery block 13, and the information detected by various detecting means are used for the secondary battery block 1
3 and the operation means 14 for determining the state of the battery pack 11, and, in some cases, communication terminals 1c and two terminals used when the device outside the battery pack 11 and the state operation device 12 of the secondary battery communicate with each other. Secondary battery status calculator 1
In some cases, the display means 19 intended to display the result determined by No. 2 is provided in the battery pack 11.

The secondary battery state calculation device 12 compares the information provided from various detection means with the information stored in the storage means 15 to determine whether to charge or discharge the secondary battery block 13. Although the charging and discharging of the battery pack 11 depends on the external device, when the state calculating device 12 of the secondary battery prohibits the charging or discharging, the external device of the battery pack 11 is charged or discharged by the communication terminal 1c. The state of the secondary battery is set by transmitting a command to prohibit or by arranging a switch element 21 arranged for the purpose of controlling charge / discharge on the charge / discharge path of the battery pack 11 as shown in FIG. You may have the structure which controls the charging / discharging of the battery pack 11 by controlling the switch element 21 by the calculating means 12.

The secondary battery state calculation device 12 has a function of grasping the charging state of the secondary battery block 13 by the voltage detecting means 16, the current detecting means 17, and the temperature detecting means 18, and charges the secondary battery block 13. In addition to the function that calculates the charged amount of electricity, which is the amount of electricity that can be discharged up to the preset state when fully charged, as 100%, the full charge state detection function of the secondary battery block, safety and performance deterioration It has a function to prevent.

FIG. 3 shows an example of changes in the amount of charge electricity depending on the usage state of the battery pack. The function of performing a relative calculation of the amount of charge electricity charged in the secondary battery block 13 is generally called a learning capacity until the secondary battery block 13 is in a fully charged state and is continuously stored in the storage unit 15. When the amount of discharged electricity that can be discharged is stored in the storage unit 15 as the total amount of charged electricity of the secondary battery block 13, and the state calculation device 12 of the secondary battery detects that the secondary battery block 13 is fully charged. First, the charge amount of the secondary battery block 13 stored in the storage means is set to the same value as the learning capacity.
The state calculating device 12 of the secondary battery calculates the charge electricity amount of the secondary battery block 13 which changes sequentially due to charging and discharging, based on the information obtained from the current detecting means 17, the voltage detecting means 16, and the temperature detecting means 18. The amount of electricity charged in the secondary battery block 13 is 0 mA when the secondary battery block 13 detects the complete discharge condition stored in advance in the storage unit 15.
Calculate as h (0%).

When the above-mentioned learning capacity is continuously discharged from the full charge detection state to the complete discharge state preset in the storage means 15 and the condition preset in the storage means 15 is satisfied, The integrated discharge current discharged from the full charge state 31 to the detection of the complete discharge state 32 is stored in the storage means 15 as a new learning capacity (step 34). There is also a discharge state 33 in which the learning capacity is not updated even if the discharge is performed up to the complete discharge state stored in the storage unit 15 due to conditions such as partial charging.

By updating the learning capacity, it becomes possible for the state calculating device of the secondary battery to cope with the change in the dischargeable current amount due to the change in the state of the secondary battery block.

FIG. 4 shows the relationship between the charge capacity and the voltage of a lithium ion secondary battery as an example. However, the diagram used is C
It is the voltage between the secondary battery terminals during C-CV charging, and the charging current and temperature are not specified.

In the lithium ion secondary battery system, the voltage of the secondary battery rises as the amount of electricity charged in the secondary battery increases. The secondary battery state calculation device 12 controls charging / discharging so that the battery voltage always exists in the normal use region. The voltage of the lithium-ion secondary battery continues to rise as it continues to be charged, and becomes a dangerous state at some point.Therefore, the secondary battery voltage is monitored and the voltage rise is controlled, as in the secondary battery status calculator. Therefore, a mechanism for ensuring safety is required.

Furthermore, for lithium ion secondary batteries, the increase in voltage affects the rate of deterioration of cell characteristics. That is, when the battery voltage is high, there is a high possibility that the speed of cell deterioration will increase. Therefore, even if charging is stopped before the secondary battery voltage reaches the overcharge region, the battery cell deterioration speed becomes faster in the normal use region near the overcharge region than in the normal use region near the overdischarge region. . On the contrary, when the secondary battery is discharged up to the voltage band in the over-discharge region, the lower the secondary battery voltage is, the faster the deterioration of the battery cell is as compared with the normal state.

Therefore, the charge state is constantly charged and discharged from the 100% state to the 0% state and the use state in which the cycle count number is increased, and the charge state is always maintained close to the full charge state, or the overdischarge state is constantly maintained. When comparing the usage state in which the cycle count is maintained and the cycle count is not increased at all, it is not appropriate to simply judge the deterioration of the battery cell by using the cycle count.

Further, the deterioration rate of the battery cell greatly affects the temperature condition. A lithium ion secondary battery that is left in a high temperature environment in a charged state close to full charge has an extremely high deterioration rate even if there is no charge / discharge current. It can be said that it is extremely important to understand the charging temperature condition experienced by the secondary battery when verifying the deterioration condition of the lithium ion secondary battery, because the temperature and the charging condition have a great influence on the deterioration rate.

Therefore, the cumulative storage of the experience time of the battery pack with respect to the battery voltage or charge capacity and the battery temperature state is shown in Table 1.
By storing in the storage means 15 in the format shown in FIG. 5, it is possible to objectively determine the battery cell deterioration state that cannot be determined by the cycle count number.

[0035]

[Table 1]

However, the temperature classification and the voltage (or capacity) classification shown in Table 1 are examples.

As an example, it is assumed that the battery pack which detects 100% is left in an environment of 25 degrees. If the state is left for 1 hour in this state, 1 hour is added to the corresponding time integration table as shown in Table 2. Similarly, when the same battery pack is discharged to an external device to be in a 60% state, and if the environment temperature is kept at 60 degrees for 2 hours, the time accumulation table indicates 2 hours. Will be added.

[0038]

[Table 2]

Even if the maintenance time of the over-discharged state is very long, the possibility of deterioration of the battery cell cannot be ignored. Therefore, if the pack battery is in the over-discharged state, the state calculation device for the secondary battery will If it can be recognized, the secondary battery state calculation device stops its function (Power Off) in order to prevent acceleration of the voltage drop in the over-discharged state of the secondary battery block that is the power source of the secondary battery state calculation device. There is also a device having a function.

FIG. 5 shows an example of a sequence for storing the time of the over-discharged state for the battery pack in the over-discharged state. Use the clock in the battery pack or the clock in the external device to which the battery pack is connected by communication to obtain the date and time from the external device before the secondary battery status calculator stops functioning. A method of storing in the storage means and calculating the period during which the secondary battery in the battery pack is over-discharged by checking the date and time when the self-function is restored by external charging again and storing it in the storage means Is shown.

From the above description, the deterioration of the secondary battery greatly depends on the temperature condition of charging / discharging or leaving. The above description shows an example in which the relationship between the mere secondary battery voltage (or capacity) and the environment (or secondary battery surface) temperature is integrated over time. Similarly, since high rate discharge in low temperature state, charge / discharge in high temperature state, etc., temperature and charge / discharge current amount are greatly related to deterioration of the secondary battery, storing as deterioration information of the secondary battery can be used for deterioration judgment. It can be important information.

[0042]

[Table 3]

As a history of the secondary battery, as shown in Table 3, the charging / discharging current amount or the charging / discharging time is stored in the storage means according to the environmental temperature (secondary battery surface temperature) and the charging / discharging current value classification. It is useful as information for determining the deterioration state of the secondary battery.

Although it is highly possible that the accumulated value of the charging / discharging time itself stored in the storage means will be smaller than that of the standing time, the charging / discharging under various temperature conditions may cause deterioration of the secondary battery. It is a very effective means because it has a great influence. The following is a description of an example of use of discharging a secondary battery in a high temperature state by taking a specific example of use.

The rechargeable battery cell that has once reached a high temperature is
It is difficult to easily lower the temperature to room temperature. When a portable notebook computer equipped with the secondary battery is left in a closed car in summer in Japan, the temperature inside the car easily rises to over 90 degrees and is left in a place exposed to direct sunlight. In this case, the surface temperature of the portable notebook computer rises to a temperature close to 100 degrees. Even if the vehicle interior temperature is lowered from such a state to the state where the vehicle interior ventilation is performed and the vehicle interior temperature is drastically lowered by the air conditioner, etc., it takes time for the secondary battery surface temperature to drop to room temperature. Will be needed. When it comes to the inside of the secondary battery,
Further time is required until the temperature stabilizes. Under the above conditions, when the power supply of the portable notebook computer left in the vehicle is in the ON state, the secondary battery holds the safe state for holding the DATA,
It is necessary to maintain the discharge. Furthermore, it should be fully considered that Joule heat is generated inside the secondary battery due to discharge.

Therefore, in normal life, the environmental temperature at which various devices using the secondary battery are used and left and the temperature change of the secondary battery due to the method of using the secondary battery are very drastic and easily changed. It is desirable to store the charging / discharging current amount or the charging / discharging time with respect to the temperature condition because there is an environmental condition in which the secondary battery deteriorates.

In the case of a battery pack in which the state of being left unstabilized by continuously repeating charging and discharging as shown in FIG. 6, it is difficult to store the history time in the storage means by the above method. In this case as well, similarly, the cycle count number is not sufficient information for estimating the deterioration rate of the secondary battery. A method of simply accumulating only the number of times of full charge detection in the storage means is simple and appropriate.

As described above, depending on the type of the secondary battery such as the lithium ion secondary battery, the closer to the full charge state, the faster the deterioration rate of the secondary battery tends to be. Accumulating and storing the number of detections can be an important clue for predicting how much the secondary battery can exist near the fully charged state.

Further, in the lithium ion secondary battery system, as shown in FIG. 7, if the secondary battery voltage level is always kept at a high level by maintaining the charge at an extremely low rate even after the full charge detection state, the charge integration Even if the amount of charge and discharge is such that there is no need to study deterioration, the deterioration rate is accelerated because the voltage of the secondary battery always maintains a high level. In this case, storing the maintenance time of the secondary battery voltage state in which it can be inferred from the secondary battery voltage that the state of full charge detection is possible, rather than the number of times the full charge state is detected, can be used to determine the degree of deterioration. Appropriate.

At this time, the charging current after the detection of full charge becomes smaller due to the difference between the voltage when the secondary battery output is released and the charging input voltage due to the increase in the secondary battery voltage. Therefore, (charge applied voltage-secondary battery release voltage) / secondary battery internal resistance = charge current, but (charge applied voltage-secondary battery release voltage) becomes small, so the calculated value becomes extremely small.

When the secondary battery is charged, a current and a voltage are applied to the secondary battery block by an external power source, so that the secondary battery voltage is maintained in a high voltage state.
Further, depending on the secondary battery system, the secondary battery itself may generate intense heat in the vicinity of full charge. Therefore, the current, voltage, and temperature at the time of detecting the fully charged state of the secondary battery are
The storage of the secondary battery is important because it significantly affects the state of deterioration of the secondary battery and the amount of electricity that can be discharged when the secondary battery is fully charged.

In a battery system different from the lithium-ion secondary battery, there is also a secondary battery such as a nickel-hydrogen storage battery in which there are a plurality of physical changes of the secondary battery which are the judgments of full charge detection (or stop of charging). The degree of deterioration of the secondary battery is different for each physical change that is a signal for full charge detection, and the amount of electricity charged by the secondary battery at the time of full charge detection (or detection of physical change that requires charging stop) is Since it greatly changes depending on the type of full charge detection, the learning capacity value is greatly affected as a result.

FIGS. 8A to 8D are graphs showing an example of changes in current, voltage and temperature during charging of a battery pack using a nickel hydrogen storage battery. As shown in various graphs in FIG. 8, generally, when charging is performed, the temperature of the secondary battery rises. The secondary battery has a charge prohibition threshold temperature set for the purpose of ensuring safety during charging and avoiding deterioration during charging, and the state where the secondary battery temperature is equal to or higher than the threshold temperature during charging is set. When detected, the state calculation device for the secondary battery recognizes the charge inhibition temperature state and stops or ends the charge (generally, TCO detection method).

In addition, the full-charge detection method for the nickel-hydrogen storage battery includes a full-charge detection method (generally ΔT detection method) based on the amount of temperature rise of the secondary battery from the start of charging, and a peak voltage during constant-current charging. There are a full charge detection method (generally -ΔV detection method) based on the amount of voltage decrease, and a method (generally dT / dt detection method) that determines the full charge state from the temperature rise gradient.

In the TCO detection method, the charging execution upper limit temperature is set in advance in consideration of safety, deterioration, and the like in charging the secondary battery, and control is performed to stop charging by detecting the upper limit temperature. The ΔT detection method performs control to detect full charge when the temperature change from the start of charging exceeds a preset value. The −ΔV detection method performs control to detect full charge when a preset voltage drop is confirmed after the secondary battery voltage shows a peak during charging with a constant current. In the dT / dt detection method, control is performed to detect full charge when a temperature gradient per preset constant time exceeds a preset constant value.

In addition, although there are several types of full charge detection methods, it is necessary to select a full charge detection method to be used depending on various conditions such as environmental temperature conditions and charging current values.

For example, when only the TCO control for stopping the charging at the time when the surface temperature of the secondary battery reaches 60 degrees is selected and executed, it is natural that the environment temperature is 40 degrees and 50 degrees. As a result, a difference occurs in the amount of electricity charged.
Further, when the charge control is performed by the temperature change, the charge rate has an extremely large effect on the amount of electricity charged in the secondary battery. Specifically, when comparing the case where 1C charging is performed and the case where 0.1C charging is performed, a large temperature change can be clearly confirmed at the time of 1C charging. By the way, when the dT / dt full charge detection method is adopted, the full charge cannot be detected unless a temperature rise of a preset temperature gradient (for example, 2 degrees / 2 minutes) is confirmed. Must be a charging current value that enables
Therefore, when the dT / dt full charge detection method is selected, the charging current needs to have a sufficient amount that a temperature change at full charge can be expected.
If the charging current is small, proper full-charge detection cannot be performed, resulting in an overcharged state.

From the above contents, it can be understood that various charging conditions such as the environmental temperature and the charging current have a great influence on the amount of electricity charged, but if further added, it is closely related to the temperature and the voltage state. It is also greatly related to the state of battery deterioration.

As an example, when the charging current value is extremely small and sufficient energy for detecting full charge cannot be obtained from the charging current, it can be detected that the secondary battery is in a fully charged state. Unable to detect a significant temperature change,
The state of charge continues, and as a result, the state of charge of the secondary battery remains overcharged and deteriorates.

From the above contents, it is important to store the state of charge of the secondary battery when the full charge is detected in the storage means as information for judging the state of deterioration of the secondary battery.

[0061]

[Table 4]

Table 4 is a condition number storage at the time of full charge detection for a battery system in which the relationship between the state of charge represented by a nickel-hydrogen storage battery system and the secondary battery voltage is not so close. When charging is stopped at less than 1 A and less than 10 degrees,
The full charge due to temperature change could not be detected.
For temperatures above 10 ° C, full charge detection based on TCO detection reduces the amount of electricity charged regardless of the charging current.
It is possible to infer that secondary battery deterioration has progressed due to charging at high temperatures.

Further, as described above, it is also necessary to consider that there is a difference in the amount of electricity charged in the secondary battery depending on the charging environmental conditions. That is, it is necessary to determine the type of full-charge detection method as information for determining the appropriateness of the updated value regarding the learning capacity.

Therefore, it is important to store the full-charge detection method, which is a major factor in storing the learning capacity recognized by the current secondary battery state calculation device.

[0065]

[Table 5]

Storing the full-charge detection method can be used to judge the state of use of the main battery device using the secondary battery and to judge the state of the secondary battery. Table 5
In the above, an example is shown in which the number of detections is stored for each type of full-charge detection of the nickel-hydrogen storage battery.

As a simple example, an example of estimation of the usage state is described for each detected content. In the TCO detection, charging is performed in a state where the power consumption state of the main body device is extremely large, and the pack battery is caused by the swinging heat of the main body. It shows the frequency of charging the internal secondary battery in a heated state, and Timer detection can obtain sufficient energy (charging current) for the secondary battery to show a fully charged state due to temperature change for some reason. Indicates that the charging time or the charging input current amount exceeds the threshold value without sufficient heat generation in the state where the charging is not performed. In other words, in the case of Timer detection, there is a high possibility that the secondary battery has reached the overcharged state, so there is a possibility that the degree of deterioration may be a concern depending on the number of times of detection.

The above is the embodiment for the purpose of storing the storage of the deterioration information in the storage means for the state where the secondary battery is in the fully charged state or the state in which the secondary battery is close to the fully charged detectable state.
Conversely, the progress of the secondary battery's discharge state, and the fact that it experiences an over-discharged state or a state close to an over-discharged state for a long time or multiple times is a major factor in accelerating the deterioration of the secondary battery. Storing the overdischarge state, which is one of the factors of deterioration, in the storage means is effective for determining the state of the secondary battery connected to the arithmetic unit.

FIG. 9 shows the discharge control and the operating state with respect to the secondary battery voltage of the secondary battery state calculating device. As illustrated in FIG. 9, when the secondary battery voltage reaches a preset secondary battery voltage V91, the secondary battery state calculation device displays a discharge prohibition signal, communicates, warns of a voltage drop, and displays V92.
2 is reached, the secondary battery voltage is prevented from lowering by performing control such that the switch 21 as shown in FIG. In this state, the state calculation device of the secondary battery does not stop its function and continues to monitor the state of the secondary battery.

When the state of being left unattended further continues, the secondary battery voltage continues to decrease due to the influence of the power consumption of the secondary battery state calculation device and the self-discharge of the secondary battery, and the preset secondary battery voltage V93 Reach In this case, the state calculation device of the secondary battery stops its own function, further reduces the current consumption of the secondary battery, and prevents the secondary battery voltage from decreasing.

As described above, the time during which the secondary battery voltage drops and the secondary battery state calculation device is in the Power Off state is stored using the clock of an external device, and the number of times the over discharge state is detected is stored. The storage method is also effective as information for determining the degree of deterioration of the secondary battery.

FIG. 10 shows the relationship between the ambient temperature, the internal resistance of the secondary battery, the static characteristics of the OCV voltage, and the discharge current for the secondary battery close to the over-discharged state. Even when the environmental temperature is significantly different, the remaining capacity charged in the secondary battery should not change within the usable temperature range, but if the discharge is stopped by detecting the constant voltage, the secondary battery Since the amount of change in the internal resistance (IR) with temperature is very large, the larger the discharge current, the more over-discharge is detected with the remaining capacity remaining inside the secondary battery. Therefore, as a general method, a technique of measuring the environmental temperature or the surface temperature of the secondary battery and changing the overdischarge detection threshold voltage together with the discharge current is used.

Therefore, the internal resistance (IR) of the secondary battery in the low temperature state is much higher than that in the room temperature state. Therefore, unless the overdischarge detection threshold voltage at the low temperature is set to be very low, It is not possible to make the remaining capacity of the discharge capacity of the same level as other temperature conditions.

In reality, before the discharge is continued until the discharge is obtained until the discharge capacity at the same level as that of other environmental temperature conditions is obtained, the discharge voltage becomes lower than the operable voltage of the externally connected device, so that the discharge capacity at the same level is obtained. Difficult to do.

However, when the secondary battery in the low temperature state is energized, Joule heat is naturally generated inside. However, since the internal resistance value is very high in the low temperature state, the Joule heat is generated in other temperature states. More intense than time,
Moreover, since it takes time to transfer heat, a large difference occurs between the temperature near the center and the temperature on the surface inside the secondary battery. Therefore, in a low temperature state, two types of extremely secondary battery deteriorations are created, namely, internal heat generation due to the energizing current and discharge of the secondary battery up to a low voltage state around the central portion.

[0076]

[Table 6]

Therefore, regarding the detection of the overdischarge state, Table 6
As described above, it is possible to store the number of times of over-discharge detection separately according to the temperature state of the secondary battery and the discharge current value and store the information as the information for determining the state of deterioration of the secondary battery. Among the functions of the secondary battery state calculation device, measuring, storing, and updating the amount of electricity that can be discharged when the secondary battery is fully charged, which is generally called the learning capacity, is the state of charge and deterioration of the secondary battery. It is an extremely important function for judging the state, and the learning capacity itself is important information.

However, since the usage conditions of the secondary battery are diverse, it cannot be said that the capacity learning value is an appropriate value. Below is an example of inappropriate learning capacity updates.

As shown in FIG. 10, the lithium-ion secondary battery left in a low temperature environment has an extremely high internal resistance as compared with a normal temperature state, and therefore, a high rate in a range allowed for normal use is obtained. Immediately after discharging, the secondary battery voltage drops to the learning execution voltage (t10a). When discharging is continued, the internal temperature of the secondary battery rises due to Joule heat, and the internal resistance of the secondary battery also decreases.Therefore, after the secondary battery voltage rises again, the remaining capacity in the secondary battery disappears. It passes through the learning execution voltage again and reaches the discharge inhibition voltage (t10
b). Therefore, although the state of charge is such that the battery can be discharged until t11b, the state calculation device for the secondary battery performs learning at time t10a by detecting the voltage. That is, the learning capacity is updated with an inappropriately small value.

With respect to the learning capacity value as described above, it is objectively judged whether it is an updated value in a primary abnormal use state or an amount of electricity actually discharged due to a change in secondary battery state such as deterioration. As a method for doing so, it is effective to separately store the learning capacity value before updating in the storage means when the learning capacity value is updated so that the change amount of the learning capacity value can be confirmed.

Further, when the secondary battery is gradually deteriorated, that is, the internal resistance of the secondary battery is increasing, the learning capacity value is also gradually decreased. Therefore, the deterioration state change can be stored in the form of the change amount of the learning capacity value of the secondary battery.

From the above, it is effective to store the update history of the learning capacity value as the information for judging the deterioration state of the secondary battery.

The storage of the history of the secondary battery cannot be applied when the storage capacity of the storage means is large and the deterioration state of the secondary battery whose history is unknown is determined. In such a case, a general determination method is to measure the internal resistance value of the secondary battery, measure the learning capacity, and compare the initial capacity of the secondary battery to determine the degree of deterioration. Therefore, it is possible to confirm and store the amount of electricity that the secondary battery can discharge when it is fully charged, that is, the learning capacity measurement can be used as one of the methods for confirming the state of deterioration of the secondary battery.

The above description is based on the premise that the state of use of the secondary battery does not exceed the range of normal use. However, if the charge / discharge inhibition state detection frequency is high for the purpose of ensuring the safety and reliability of the secondary battery, there is a concern that the state of deterioration of the secondary battery may be accelerated.

As an example, when it is detected that the secondary battery is discharging a discharge current equal to or higher than a preset threshold value, the secondary battery state calculation device uses a switch 21 or the like as shown in FIG. To interrupt the discharge current. The cutoff speed of the abnormal discharge current by the switch is about several milliseconds to several seconds, but in the case of an abnormal current such as the Short current,
Since a current that is several tens of times the discharge current that is normally used flows, a large number of experiences greatly affects the deterioration of the secondary battery. Therefore,
Storing the number of abnormal state detections for each abnormal state type is effective for verifying the degree of deterioration of the secondary battery.

[0086]

As described above, the state calculating device for a secondary battery according to the present invention can be used not only for estimating the deterioration state of the secondary battery based on the memory of the detailed usage history of the connected secondary battery. Therefore, it becomes possible to provide information for clarifying the cause of the characteristics of the current secondary battery.

[Brief description of drawings]

FIG. 1 is a block diagram of a state calculation device for a secondary battery according to an embodiment of the present invention.

FIG. 2 is a schematic block diagram of a battery pack in which charge / discharge is controlled by a state calculation device for a secondary battery that is an embodiment of the present invention.

FIG. 3 is a graph showing an example of the charging / discharging state of the battery pack, the point of full discharge detection of the secondary battery and the point of full charge detection, and the timing of carrying out capacity learning.

FIG. 4 is a graph showing a general example of a charge capacity state, a secondary battery voltage, and a secondary battery state of a lithium ion secondary battery.

FIG. 5A is a flowchart until the function of the secondary battery state calculation device is stopped. FIG. 5B is another flowchart until the function of the secondary battery state calculation device is stopped.

FIG. 6 is a graph showing the relationship between the secondary battery voltage or charge capacity and the charge control state near the full charge detection state.

FIG. 7 is a graph showing current / voltage changes during continuous charging after detection of full charge, regarding current / voltage changes during constant current / constant voltage charging in a lithium-ion secondary battery system.

8A is a diagram showing TCO detection charge control of a nickel-hydrogen storage battery, FIG. 8B is a diagram showing ΔT detection charge control of a nickel-hydrogen storage battery, and FIG. 8C is a diagram showing −ΔV detection charge control of a nickel-hydrogen storage battery. d) Diagram showing dT / dt detection charge control of nickel-hydrogen storage battery

FIG. 9 is a diagram showing operation timings of various functions of the secondary battery state calculation device with respect to secondary battery discharge voltage characteristics.

FIG. 10 (a) is a diagram showing discharge temperature and discharge current characteristics in a lithium ion secondary battery, and (b) is a discharge temperature in a lithium ion secondary battery,
Another figure showing discharge current characteristics

[Explanation of symbols]

11-pack battery 12 Secondary battery status calculator 13 Secondary battery block 14 Computing means 15 storage means 16 Voltage detection means 17 Current detection means 18 Temperature detection means 19 Display means 1a Charge / discharge terminal 1b Charge / discharge terminal 1c communication terminal 21 Charge / discharge control switch element

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2G016 CB12 CB21 CB31 CC01 CC03                       CC04 CC06 CC10 CC12 CC21                       CF06                 5G003 BA01 CA01 CA11 CB01 EA02                       EA05 EA06 EA08 GC05                 5H030 AS11 BB01 FF24 FF42 FF43                       FF44 FF52

Claims (7)

[Claims] 1. A state calculation device for a secondary battery, which is connected to a battery block composed of one or a plurality of secondary battery cells, and which calculates, communicates, or displays the amount of electricity charged in the battery block that increases or decreases due to charging and discharging. A voltage detecting means for monitoring various cell voltages forming the battery block, a current detecting means for detecting a charging / discharging current of the battery block, a temperature detecting means for detecting a surface temperature of the battery block, and the voltage detecting means. Means and means for calculating the state of the battery block using the electric signal obtained from the current detection means, and storage means for storing various information through the calculation means, the calculation means, the battery block The storage time is stored as the experience time or the amount of charge / discharge current for each charge / discharge current for the temperature condition to be experienced. State calculating device for a secondary battery that. 2. The calculating means detects the full charge state of the battery block from the information obtained by the voltage detecting means, the current detecting means and the temperature detecting means, and stores the full charge detection frequency of the battery block in the storing means. Claim 1 characterized by the above.
The state calculation device for the secondary battery described. 3. The computing means is configured to detect various currents, voltages and temperatures, or full charge detection determination conditions when the fully charged state of the battery block is detected from the information obtained by the voltage detection means, the current detection means and the temperature detection means. 2. The state calculating device for a secondary battery according to claim 1, wherein the number of times of detection is accumulated and stored for each type. 4. The arithmetic means stores the number of times of detection of an overdischarge voltage set value preset in the storage means in the discharge state from the information obtained by the voltage detection means, the current detection means and the temperature detection means. The state calculation device for the secondary battery according to claim 1. 5. The calculation means has a function of calculating and updating the amount of electricity that can be discharged from the connected battery block when the battery block is fully charged, based on the information obtained by the voltage detection means, the current detection means, and the temperature detection means. 2. The rechargeable battery according to claim 1, wherein the rechargeable secondary battery before updating stores the rechargeable electric amount when the battery block is fully charged in the storage means when the rechargeable electric amount is updated. State calculator. 6. The calculation means stores and updates the full-charge detection determination condition in the storage means for each full-charge detection, and when calculating and updating the amount of electricity that the connected secondary battery block can discharge when full-charged. 2. The state calculation device for a secondary battery according to claim 1, wherein the full-charge detection determination condition stored in the storage means is stored as a full-charge detection method that is the basis of the updated calculation value. 7. The arithmetic means is a prevention function that determines the number of times the safety or performance deterioration prevention function is performed by the secondary battery state arithmetic device based on information obtained from the voltage detection means, the current detection means and the temperature detection means. The state calculating device for a secondary battery according to claim 1, wherein the state calculating device stores the data in each storage unit.