JP2005037230A - Battery degradation detection device and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly accurate battery degradation detection device and a method. <P>SOLUTION: When a degradation determination device is switched to the ON state (S400), a current sensor 16 measures a battery current i<SB>n</SB>(S402), and an estimated charge/discharge current I<SB>n</SB>is operated (S404). Measured SOC:s<SB>n</SB>is determined by integrating the battery current i<SB>n</SB>(S406). Estimated SOC:S<SB>n</SB>is determined by integrating the estimated charge/discharge current I<SB>n</SB>(S408). The SOC difference (S<SB>n</SB>-s<SB>n</SB>) which is a difference between the estimated SOC and the measured SOC is determined (S410). An integrated SOC value is determined by integrating the change with age of the SOC difference (S<SB>n</SB>-s<SB>n</SB>) (S412). A primary integration quantity of the difference quantity between the estimated SOC:S<SB>n</SB>and the measured SOC:s<SB>n</SB>which is a standard of capacity degradation of the battery 10 is compared with the integrated SOC value (S414). When the integrated SOC value becomes higher than a prescribed value by comparison with the primary difference quantity, the battery 10 is degraded (S420), namely, degradation of the battery is detected (S418). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a battery deterioration detection apparatus and method.

  Conventionally, a hybrid electric vehicle having a generator that generates electric power by driving or regenerating by an engine and a motor that is driven by electric power from a battery and drives driving wheels, and an electric vehicle including the hybrid vehicle include a nickel metal hydride battery, A secondary battery for driving a motor (that is, a battery) such as a lithium ion battery is used. As the battery continues to be used, the electrolyte deteriorates and its capacity decreases (capacity deterioration). When the capacity is deteriorated, various measures such as quickly replacing the battery are necessary, and it is a big problem to accurately detect the capacity deterioration.

  In order to determine capacity deterioration, there is a method using SOC (State of Charge). The SOC is one of the quantities representing the state of charge of the battery. Here, the SOC will be described. Generally, it is assumed that the SOC is 100% in the fully charged state, while the SOC is 0% indicates that the charged amount is zero. In the battery, the open-circuit voltage Vocv and the SOC have a one-to-one correspondence. Therefore, the open circuit voltage Vocv of the battery is measured or estimated, and the SOC corresponding to the open circuit voltage Vocv can be obtained from the Vocv-SOC correlation.

  On the other hand, it is also known that the SOC (charge / discharge current) value is integrated to estimate the SOC. Since the SOC varies depending on the vehicle running state (for example, idle stop, start, normal running, acceleration, deceleration, etc.) and vehicle load (stop lamp, headlamp, wiper, electric fan, etc.), Need to be estimated.

  For example, in Patent Document 1, when a current sensor that detects an actual charging / discharging current of a battery is normal, the SOC is obtained by integrating the charging / discharging current values detected by the battery ECU, while the current sensor In the case of an abnormality, since it is impossible to detect the SOC by integrating the charge / discharge current, an SOC estimation device has been proposed in which the battery ECU estimates the SOC of the battery based on the battery voltage detected by the voltage detector.

An apparatus that determines battery capacity deterioration from the SOC obtained in this way is described in Patent Document 2. In this document, the upper threshold voltage and the lower threshold voltage of the battery are set, the remaining capacity when the measured voltage reaches one of the threshold values, and the other threshold value is reached. There has been proposed a battery deterioration determination device that obtains a capacity difference between remaining capacity and determines battery capacity deterioration.
JP 2000-166105 A JP 2000-224701 A

  However, in the battery charge deterioration determination device described in Japanese Patent Application Laid-Open No. 2000-224701, the battery upper limit threshold voltage (for example, a voltage corresponding to SOC 80%) and the lower limit threshold voltage (for example, a voltage corresponding to SOC 20%). The battery capacity deterioration cannot be determined unless both of the threshold values are reached. Determining the deterioration of the battery of an electric vehicle with this apparatus is limited to the vehicle running mode that reaches both the upper threshold voltage and the lower threshold voltage of the battery, and may be inconvenient.

  An example will be described in which the upper threshold voltage is a voltage corresponding to SOC 80% and the lower threshold voltage is a voltage corresponding to SOC 20% as described in the publication. In general, an electric vehicle is basically controlled so that the SOC of a battery is a predetermined small constant width (for example, SOC 40% to 60%). Thus, a low SOC of SOC 20% or SOC 80% A high SOC is rarely reached. Furthermore, reaching both thresholds is even more rare. Assuming a case where the battery charge deterioration judging device described in Japanese Patent Application Laid-Open No. 2000-224701 can be used, the battery is charged by regenerative power generation from the top of the mountain to the foot of the mountain, and the SOC is increased to raise the SOC. Then, the vehicle travels to the top of the mountain at full acceleration and discharges the battery, and the SOC is lowered to reach the lower threshold voltage of the battery. Such a usage mode is a rare mode for the user, and a battery deterioration determination method that requires such a usage mode may not be practical.

  The present invention has been made in view of the above-described problems and the like, and an object thereof is to provide a more accurate battery deterioration detection device and method.

  The battery deterioration detecting device for detecting the capacity deterioration of the secondary battery according to the present invention includes an actual voltage detecting means for detecting an actual voltage of the secondary battery, and an estimated charge / discharge for calculating an estimated charge / discharge current based on the actual voltage. Current calculating means; current detecting means for detecting an actual charging / discharging current that is at least one of a charging current and a discharging current of the secondary battery; and a current comparing means for comparing the estimated charging / discharging current with the actual charging / discharging current. And deterioration detecting means for detecting deterioration of the secondary battery based on the comparison result obtained by the current comparing means.

  In the above apparatus, it is preferable that the current comparison unit calculates a current difference between the estimated charge / discharge current and the actually measured charge / discharge current, and compares the current difference with a predetermined current difference set in advance.

  In the above apparatus, the current comparing means calculates an integrated value difference between the integrated value of the estimated charge / discharge current and the integrated value of the actually measured charge / discharge current, and the integrated value difference and a predetermined integrated value difference set in advance are calculated. Is preferable.

  In the above apparatus, the current comparing means calculates an integrated value difference between the integrated value of the estimated charging / discharging current and the integrated value of the actually measured charging / discharging current, and a change amount of the integrated value difference and a preset predetermined integrated value It is preferable to compare the value difference change amount.

  In the above apparatus, the current comparing means calculates a current difference integrated value of a current difference between the estimated charge / discharge current and the measured charge / discharge current, and the current difference integrated value and a predetermined current difference integrated value set in advance. Is preferable.

  In the above apparatus, the current comparison means calculates a current difference integrated value of a current difference between the estimated charge / discharge current and the actually measured charge / discharge current, and a change amount of the current difference integrated value and a preset predetermined current difference It is preferable to compare the integrated value.

  In the above apparatus, it is preferable that the current comparison unit calculates a current ratio between the estimated charge / discharge current and the actually measured charge / discharge current, and compares the current ratio with a preset predetermined current ratio.

In the above apparatus, the estimated charge / discharge current calculating means calculates the estimated charge / discharge current according to the following formula (1).
I _n = (V−V _OCVn−1 ) / R _n (1)
(Where I _n represents the estimated charge-discharge current, V is the measured voltage, V _OCVn-1 are open circuit voltage, the R _n internal resistance.)

  A battery deterioration detection method for detecting capacity deterioration of a secondary battery according to the present invention includes an actual voltage detection step for detecting an actual voltage of the secondary battery, and an estimated charge / discharge for calculating an estimated charge / discharge current based on the actual voltage. A current calculation step; a current detection step for detecting an actual charge / discharge current that is at least one of a charge current and a discharge current of the secondary battery; and a current comparison step for comparing the estimated charge / discharge current with the actual charge / discharge current. And a deterioration detection step of detecting deterioration of the secondary battery based on the comparison result obtained by the current comparison step.

  In the above method, it is preferable that the current comparison step calculates a current difference between the estimated charging / discharging current and the actually measured charging / discharging current, and compares the current difference with a predetermined current difference set in advance.

  In the above method, the current comparing step calculates an integrated value difference between the integrated value of the estimated charge / discharge current and the integrated value of the actually measured charge / discharge current, and the integrated value difference and a predetermined integrated value difference set in advance are calculated. Is preferable.

  In the above method, the current comparison step calculates an integrated value difference between the integrated value of the estimated charge / discharge current and the integrated value of the actually measured charge / discharge current, and a change amount of the integrated value difference and a predetermined predetermined integrated value are calculated. It is preferable to compare the value difference change amount.

  In the above method, the current comparison step calculates a current difference integrated value of a current difference between the estimated charge / discharge current and the measured charge / discharge current, and the current difference integrated value and a predetermined current value integrated value set in advance Is preferable.

  In the above method, the current comparison step calculates a current difference integrated value of a current difference between the estimated charge / discharge current and the actually measured charge / discharge current, and a change amount of the current difference integrated value and a preset predetermined current difference It is preferable to compare the integrated value change amount.

  In the above method, the current comparison step preferably calculates a current ratio between the estimated charge / discharge current and the actually measured charge / discharge current, and compares the current ratio with a predetermined current ratio set in advance.

In the above method, it is preferable that the estimated charging / discharging current calculating step calculates the estimated charging / discharging current by the following formula (1).
I _n = (V−V _OCVn−1 ) / R _n (1)
(Where I _n represents the estimated charge-discharge current, V is the measured voltage, V _OCVn-1 are open circuit voltage, the R _n internal resistance.)

  The present invention can provide a more accurate battery deterioration detection apparatus and method.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Embodiment 1 FIG.
<First device configuration example: detection of deterioration due to difference between estimated charge / discharge current and battery current>
[Configuration in which the battery deterioration detection device is applied to a hybrid electric vehicle]
FIG. 1 is a block diagram showing the configuration of a system in which the battery deterioration detection device of the present embodiment is applied to a battery of a hybrid electric vehicle. The battery 10 is an assembled battery in which a large number of battery cells are connected in series, and includes, for example, a secondary battery cell such as a Ni-based battery (for example, a nickel metal hydride (Ni-MH) battery) or a lithium ion battery.

  An actual measurement voltage (hereinafter referred to as a battery voltage) which is the current voltage of the battery 10 is measured by the voltage detector 12 which is an actual voltage detection means and supplied to the battery ECU 14. The battery ECU 14 is also connected to a current sensor 16 which is an actual charging / discharging current detecting means for detecting an actual charging / discharging current (hereinafter referred to as a battery current) which is a current current of the battery. The current value is supplied to the battery ECU 14. Further, the battery 10 is provided with a thermometer 26 for detecting the battery temperature, and the detected battery temperature value is also supplied to the battery ECU 14. Here, the thermometer 26 is arranged inside the battery 10 or on the surface of the battery 10 or in the vicinity of the surface. An initial open-circuit voltage measuring relay 1 is provided between the battery 10 and the current sensor 16, while an initial open-circuit voltage measuring relay 2 is also provided between the battery 10 and the DC / DC converter 32. Is provided. The DC / DC converter 32 is connected to a vehicle load 38 via a 12V battery 36. Examples of the vehicle load 38 include a stop lamp, an electric fan, a blower, a headlight, a fog lamp, a defogger, and a wiper. The HVECU 18 receives a signal from the accelerator sensor 30 and the like, further issues an engine output command to the E / GECU 28 that controls the output of the engine 24 and the like, and receives engine output control information from the E / GECU 28. Further, the HVECU 18 outputs a torque command or the like to the motor to the motor ECU 38 and inputs motor control information from the motor ECU 38. Further, the motor ECU 38 performs switching control in the inverter 20. Thereby, the input to the motor generator 22 is determined, and the driving wheels can be driven according to the output. In the present embodiment, the configuration in which the voltage detection means, the current detection means, and the thermometer are arranged one by one has been described. However, the present invention is not limited to this, and the voltage detection means, A plurality of current detection means and thermometers may be arranged at a plurality of locations, for example, for each cell. Further, the current sensor 16 as the current detection means shown in FIG. 1 may be, for example, a magnetic detection type current sensor.

  The battery ECU 14 calculates the internal resistance based on both the supplied battery voltage and battery current. And the below-mentioned estimated charging / discharging electric current obtained from a battery voltage, the open circuit voltage of a battery, and internal resistance is calculated. Then, the SOC is obtained by integrating the estimated charge / discharge current. The battery ECU 14 stores the relationship between the obtained SOC and the open circuit voltage, and the open circuit voltage can be obtained from the SOC. Then, the battery ECU 14 supplies the SOC detected by any of the SOC detection means to the HVECU 18.

  The HVECU 18 determines a torque command based on information such as the accelerator opening, the brake depression amount, the vehicle speed, and performs control so that the output of the motor generator 22 matches the torque command. That is, the HVECU 18 controls switching in the inverter 20 and controls the output of the engine 24. Thereby, the input to the motor generator 22 is determined, and the output of the motor generator 22 is controlled to match the torque command.

  Further, the battery 10 is charged or charged depending on, for example, the vehicle running state (for example, start, normal running, acceleration, deceleration, etc.), the vehicle load (stop lamp, headlamp, wiper, electric fan, etc.) and the battery charging state. Discharged.

[Calculation of estimated charge / discharge current]
Next, an example of the calculation of the estimated charge / discharge current and the open circuit voltage according to the present invention will be described with reference to FIG. These calculations are generally performed by the battery ECU 14. The present invention is not limited to the following calculation of estimated charge / discharge current.

That is, when the IG (ignition) of the electric vehicle having the configuration shown in FIG. 1 is turned on, the voltage detector 12 measures the initial battery voltage V ₀ before the relays 1 and 2 are turned on (S100). Next, the initial battery voltage V ₀ is set as the open circuit voltage V _OCV1 (S102). Next, the current battery voltage V _n (n is 1 to n and does not include 0; the same applies hereinafter) under the load state after the relay 1 and the relay 2 are turned on in the voltage detector 12 is also relayed in the current sensor 16. 1. The current battery charge / discharge current i _n under the load state after the relay 2 is turned on is measured (S104). Based on the battery voltage V _n and the actually measured battery current i _n , the battery internal resistance R _n is obtained (S106). Next, the estimated charging voltage is estimated using the measured battery voltage V _n , the battery open-circuit voltage V _OCVn−1 obtained based on the previously estimated state of charge (SOC), and the battery internal resistance R _n obtained by the calculation. it can be determined discharge current I _n (S108). However, in this S108, the estimated the first time of operation of the charge and discharge current I _n, using the measured voltage V ₀ which battery as the open circuit voltage V _OCVn-1 of the battery. Next, SOC _n is estimated by integrating the estimated charge / discharge current I _n (S110). It should be _noted that V _OCVn-1 is obtained based on the obtained SOC _n using a map of the correlation between the SOC stored in advance and the open circuit voltage V _ocv (S112), and the next time based on this V _OCVn-1. You can obtain the estimated charge-discharge current I _n. The internal resistance R _n may be a predetermined value without being obtained as in the above example. In this case, the process of obtaining the internal resistance R _n can be omitted except for the battery charge / discharge current i _n that is required later.

[Battery deterioration detection]
Then, by detecting the battery deterioration from the current difference of the estimated charge-discharge current I _n and the battery current i _n described method for determining deterioration of the battery on the basis of FIG. This deterioration determination is generally performed by the battery ECU 14.

When the deterioration determination device is ON (S200), the current sensor 16 measures the battery current i _n (S202). Estimated discharge current I _n is calculated therewith (FIG. 2: S306). Then current difference which is a difference between the estimated charge-discharge current I _n the battery current i _n Request _{(I n -i n) (S206} ). Predetermined current difference of the estimated charge-discharge current I _n and the battery current i _n that serves as a reference when the capacity deterioration of the battery 10 has occurred (initial difference amount) is stored in advance (S210). The initial difference amount is compared with the current difference (S208). When the current difference is compared with the initial difference amount and the current difference is equal to or greater than the initial difference amount, it is determined that the battery 10 has deteriorated (S214) based on the battery deterioration detection principle described later (S212). If smaller than the predetermined initial difference amount measurement is made again battery current i _n and the estimated charge-discharge current I _n, S202~S212 steps are repeated. Further, where it is also possible to detect deterioration by using the current ratio (I _n / i _n) instead of the current difference (I _n -i _n).

[Battery deterioration detection principle]
Next, a description is given of a principle of detecting the estimated charge-discharge current I _n and the battery current i _n the battery deterioration. Assume that the capacity of the battery has deteriorated, for example, the capacity has deteriorated from a charge / discharge amount of 100 Ah to a charge / discharge amount of 50 Ah. Then, the battery determines that 100 Ah is SOC 100% (full charge capacity), whereas 50 Ah is determined to be SOC 100% (full charge capacity). That is, even if it is the same SOC, the battery capacity corresponding to it changes. Since the battery capacity corresponds to the actually measured voltage, when the capacity is deteriorated, the capacity deterioration is reflected in the actually measured voltage V _n . Then, the measured voltage V _n changes before and after the capacity deterioration. Then, the estimated charge / discharge current I _n (in FIG. 2, (formula: I _n = (V _n −V _OCVn−1 ) / R _n )) obtained by dividing the actually measured voltage V _n by the internal resistance R _n is a capacity deterioration. It will change before and after capacity degradation.

However, the measured charging and discharging current i _n respect of the estimated charge-discharge current I _n changes are nearly identical. Therefore, comparing with the measured charging and discharging current i _n the estimated charge-discharge current I _n, and thus capable of determining the deterioration of the battery based on the value. Comparative Comparative Methods of, for example, the current difference between the measured charging and discharging current i _n and the estimated charge-discharge current _{I n (I n -i n)} , current ratio (I _n / i _n) and the previously stored predetermined value To do.

"Current difference":
While current difference (I _n -i _n) is constant weight before capacity deterioration, by I _n value changes by capacity deterioration occurs, Then the estimated charge-discharge current I _n is a large value Accordingly, the current difference (I _n −i _n ) of the actually measured charge / discharge current i _n changes. Therefore, by comparing the current difference (I _n −i _n ) with the initial difference amount stored in advance, it is possible to detect that the battery 10 has deteriorated when the current difference exceeds a predetermined current difference.

"Current ratio":
Although current ratio of I _n and i _n before capacity deterioration (I _n / i _n) is within the predetermined range, after the capacity deterioration, the ratio of I _n and i _n varies by a change in I _n associated therewith. For example, it is assumed that I _n = 5.5 A and i _n = 5.0 A before the capacity deterioration, and the current ratio (I _n / i _n ) = 1.1. Here capacity deterioration occurs, the value of I _n becomes altered I _n = 10.0A. Then it changes to the current ratio _{(I n / i n) =} 2.0. Here, if the capacity deterioration is set at a predetermined current ratio I _n / i _n = 1.8 or more stored in advance, it is possible to detect that the capacity deterioration occurs in the battery by satisfying the requirement of this ratio or more. The method using this current ratio can prevent erroneous determination even when a sudden large current flows through the battery.

  In addition, instead of detecting deterioration using the current difference and current ratio, a predetermined integration in which the change amount is stored in advance based on the integrated current difference obtained by integrating the current difference with the obtained change amount of the current difference with time. It is also possible to detect the capacity deterioration when the battery capacity is deteriorated when it is larger than the current difference change amount.

Embodiment 2. FIG.
<Second Device Configuration Example: Deterioration Detection Based on Difference between Estimated SOC Based on Estimated Charge / Discharge Current and Actually Determined SOC Based on Battery Current>
Configuration was applied battery degradation detection device in a hybrid electric vehicle and the estimated charge-discharge operation of the current I _n]
Device configuration of the first embodiment (FIG. 1) and calculation of the estimated charge-discharge current I _n (FIG. 2) are similar.

[Battery deterioration detection]
Next, based on FIG. 4 respectively current integration estimation charge-discharge current I _n and the battery current i _n and the in the second embodiment, the estimated SOC, obtains the measured SOC, the deterioration of the battery by detecting the deterioration of the battery A determination method will be described. This deterioration determination is generally performed by the battery ECU 14.

When the deterioration determination device is ON (S300), the current sensor 16 measures the battery current i _n (S302). Estimated discharge current I _n is calculated therewith (FIG. 2: S304). By accumulating the battery current i _n , an actual measured SOC: s _n which is the accumulated value is obtained (S306). Estimated discharge current is the integrated value by integrating the I _n estimated SOC: Request S _n (S308). The difference between these integrated values, that is, the SOC difference (S _n −s _n ) that is the difference between the estimated SOC and the actually measured SOC is obtained (S310). Estimated SOC serving as a reference when the capacity deterioration of the battery 10 occurs: S _n and the measured SOC: the amount of difference s _n (initial difference amount) is stored in advance (S314). The initial difference amount is compared with the SOC difference (S312). When the SOC difference is equal to or larger than the predetermined SOC difference compared with the initial difference amount, it is determined that the battery 10 is deteriorated (S318) based on a deterioration detection principle described later (S316). If smaller than the predetermined SOC difference measurement is made again battery current i _n and the estimated charge-discharge current I _n, S302~S316 steps are repeated. Here, it is also possible to detect the deterioration using the SOC ratio S _n / s _n instead of the SOC difference (S _n −s _n ).

[Battery deterioration detection principle]
Next, the principle of detecting the deterioration of the battery from the difference between the SOC based on the estimated charge / discharge current and the SOC based on the battery current will be described.

FIG. 5A is a graph showing a change with time in the SOC of the battery after capacity deterioration. Wherein (1) shows the time course of the estimated SOC obtained by integrating the estimated charge-discharge current I _n, (2) shows the time course of the measured SOC obtained by integrating the measured charging and discharging current i _n. Estimated discharge current I _n reflects the capacity deterioration. Therefore, changes in the estimated SOC to be integrated in the estimated charge-discharge current I _n after the capacity deterioration becomes large. On the other hand, the measured charge / discharge current i _n hardly changes before and after the capacity deterioration. Increases or decreases of the measured charge-discharge current measured SOC obtained by integrating at i _n hardly changed before and capacity degradation. Therefore, the SOC difference (S _n −s _n ) between the estimated SOC and the actually measured SOC becomes a larger value than before the capacity deterioration. Therefore, when this SOC difference (S _n −s _n ) is compared with an initial difference amount stored in advance as a reference for the occurrence of the capacity deterioration, the battery 10 is detected when the SOC difference becomes equal to or larger than the initial difference amount. Can be detected.

In Embodiment 2, the estimated SOC, measured SOC can be obtained respectively the estimated charge-discharge current I _n, by integrating the measured charging and discharging current i _n. When the capacity is deteriorated, a current difference (I _n −i _n ) is generated, and this difference is enlarged by integration. Then, the SOC difference (S _n −s _n ) can be detected as a change in value larger than the current difference (I _n −i _n ), and the capacity deterioration can be detected more reliably. Further, there is an advantage that the integration process is less susceptible to noise.

Embodiment 3 FIG.
<Third apparatus configuration example: Deterioration detection based on an integrated value of changes over time of estimated SOC based on estimated charge / discharge current and measured SOC based on battery current>
Configuration was applied battery degradation detection device in a hybrid electric vehicle and the estimated charge-discharge operation of the current I _n]
Embodiments 1 and 2 and device configuration according (Figure 1) and calculation of the estimated charge-discharge current I _n (FIG. 2) is the same in this embodiment.

[Battery deterioration detection]
Then, based on the estimated charge-discharge current I _n and each estimated SOC from the battery current i _n, obtains a measured SOC, integration SOC value obtained by integrating the difference between the estimated SOC and the measured SOC in the third embodiment with reference to FIG. 6 A method for detecting battery deterioration and determining battery deterioration will be described. This deterioration determination is generally performed by the battery ECU 14.

When the deterioration determination device is ON (S400), the current sensor 16 measures the battery current i _n (S402). Estimated discharge current I _n is calculated therewith (FIG. 2: S404). Found by integrating the battery current i _n SOC: Request s _n (S406). Estimated by integrating the estimated charge-discharge current I _n SOC: Request S _n (S408). An SOC difference (S _n −s _n ) that is a difference between the estimated SOC and the actually measured SOC is obtained (S410). An accumulated SOC value is obtained by integrating the amount of change with time of the SOC difference (S _n −s _n ) (S 412). The integrated value (initial integrated amount) of the difference amount between the estimated SOC: S _n and the actually measured SOC: s _n that serves as a reference for the capacity deterioration of the battery 10 is stored in advance (S416). The initial integrated amount is compared with the integrated SOC value (S414). When the integrated SOC value is equal to or greater than a predetermined value in comparison with the initial difference amount, it is determined that the battery 10 has deteriorated (S420) based on a deterioration detection principle described later (S418). If smaller than the predetermined ratio measurement is made again battery current i _n and the estimated charge-discharge current I _n, S402~S418 steps are repeated. It is also possible to detect deterioration with SOC ratio S _n / s _n.

[Battery deterioration detection principle]
Next, the principle of detecting the deterioration of the battery from the integrated value of the difference between the SOC based on the estimated charge / discharge current and the SOC based on the battery current will be described.

When the capacity of the battery is deteriorated, a difference in the SOC difference (S _n −s _n ) between the estimated SOC: S _n and the actually measured SOC: s _n occurs (FIG. 5A). It is possible to detect that the battery 10 is deteriorated by comparing the integrated SOC value obtained by integrating the SOC difference (S _n −s _n ) with the initial integrated value. FIG. 5B shows the relationship between the accumulated SOC obtained by integrating the SOC difference (difference between (1) and (2): S _n −s _n ) of FIG. 5A and time.

In the third embodiment, by integrating the SOC difference (S _n −s _n ) between the estimated SOC and the actually measured SOC, this difference is also enlarged, and deterioration can be detected more reliably. Further, there is an advantage that the integration process is less susceptible to noise.

The present invention, by utilizing the relationship that the estimated charge-discharge current I _n capacity deterioration of the secondary battery occurs changes, determines the capacity deterioration of the battery. Various aspects and mathematical formulas can be inferred as long as deterioration detection is performed to determine the capacity deterioration of the secondary battery using this relationship. For example, a correction device that detects the deterioration of the secondary battery and corrects the battery capacity is also conceivable.

  INDUSTRIAL APPLICABILITY The present invention can be used as a battery deterioration detection apparatus and b method for all electric vehicles having secondary battery batteries (for example, fuel cell vehicles, hybrid electric vehicles using both fuel cells and internal combustion engines). In the present invention, the battery deterioration detecting device and method of the present invention can be applied to various batteries such as mini vehicles, passenger cars, large / small special vehicles, large vehicles (buses, trucks).

  In addition, the present invention is used in all devices having secondary batteries (for example, lithium ion secondary batteries, Ni-based batteries (for example, Ni-MH batteries, Ni-Cd batteries), lead storage batteries) without being caught by automobiles. And deterioration of the secondary battery provided in the device can be detected. For example, the present invention can also be applied to detection of secondary battery deterioration required for power storage of household / commercial power generation fuel cells. In addition, the present invention can also be applied to detection of deterioration of a secondary battery provided in a moving body such as an aircraft, a ship, personal computer related devices, and a mobile phone.

It is a block diagram which shows the structure of the system which applied the battery charge condition estimation apparatus of Embodiment 1-3 of this invention to the hybrid electric vehicle. It is a flowchart which calculates | requires the estimated charging / discharging current and estimated SOC of Embodiment 1-3 of this invention. It is a flowchart explaining the battery deterioration detection method of Embodiment 1 of this invention. It is a flowchart explaining the battery degradation detection method of Embodiment 2 of this invention. (A) It is a related figure which shows the SOC time-dependent change of the battery after capacity deterioration. (B) It is a relationship figure which shows the relationship between integration SOC and time. It is a flowchart explaining the battery degradation detection method of Embodiment 3 of this invention.

Explanation of symbols

  1, 2 relay, 10 battery, 12 voltage detector, 14 battery ECU, 16 current sensor, 18 HVECU, 20 inverter, 22 motor generator, 24 engine, 26 thermometer, 28 E / GECU, 30 accelerator sensor, etc. 32 DC / DC converter, 36 12V battery, 38 vehicle load.

Claims (16)

A battery deterioration detection device that detects a capacity deterioration of a secondary battery,
An actual voltage detecting means for detecting an actual voltage of the secondary battery;
Estimated charge / discharge current calculating means for calculating an estimated charge / discharge current based on the measured voltage;
Current detection means for detecting an actual charge / discharge current which is at least one of a charge current and a discharge current of the secondary battery;
Current comparison means for comparing the estimated charge / discharge current and the measured charge / discharge current;
A deterioration detecting means for detecting deterioration of the secondary battery based on the comparison result obtained by the current comparing means;
A battery deterioration detecting device having The battery deterioration detection device according to claim 1,
The current comparison means calculates a current difference between the estimated charge / discharge current and the measured charge / discharge current, and compares the current difference with a predetermined current difference set in advance. The battery deterioration detection device according to claim 1,
The current comparing means calculates an integrated value difference between the integrated value of the estimated charge / discharge current and the integrated value of the actually measured charge / discharge current, and compares the integrated value difference with a preset predetermined integrated value difference. Deterioration detection device. The battery deterioration detection device according to claim 1 or 3,
The current comparison means calculates an integrated value difference between the integrated value of the estimated charge / discharge current and the integrated value of the actually measured charge / discharge current, and a change amount of the integrated value difference and a predetermined integrated value change amount set in advance. A battery deterioration detection device for comparing the two. The battery deterioration detection device according to claim 1,
The current comparing means calculates a current difference integrated value of a current difference between the estimated charge / discharge current and the measured charge / discharge current, and compares a predetermined current difference integrated value set in advance based on the current difference integrated value. Battery deterioration detection device. The battery deterioration detection device according to claim 1 or 5,
The current comparison means calculates a current difference integrated value of a current difference between the estimated charge / discharge current and the measured charge / discharge current, and a predetermined current difference integrated value preset based on a change in the current difference integrated value, A battery deterioration detection device for comparing the two. The battery deterioration detection device according to claim 1,
The current comparison means calculates a current ratio between the estimated charge / discharge current and the measured charge / discharge current, and compares the current ratio with a predetermined current ratio set in advance. The battery deterioration detection device according to any one of claims 1 to 7,
The estimated charge / discharge current calculation means is a battery deterioration detection device that calculates an estimated charge / discharge current according to the following mathematical formula (1).
I _n = (V−V _OCVn−1 ) / R _n (1)
(Where I _n represents the estimated charge-discharge current, V is the measured voltage, V _OCVn-1 are open circuit voltage, the R _n internal resistance.) A battery deterioration detection method for detecting capacity deterioration of a secondary battery,
An actual voltage detection step of detecting an actual voltage of the secondary battery;
An estimated charge / discharge current calculation step of calculating an estimated charge / discharge current based on the measured voltage;
A current detection step of detecting an actual charge / discharge current that is at least one of a charge current and a discharge current of the secondary battery;
A current comparison step of comparing the estimated charge / discharge current and the measured charge / discharge current;
A deterioration detecting step of detecting deterioration of the secondary battery based on the comparison result obtained by the current comparing step;
A method for detecting battery deterioration. The battery deterioration detection method according to claim 9,
The current comparison step calculates a current difference between the estimated charge / discharge current and the measured charge / discharge current, and compares the current difference with a predetermined current difference set in advance. The battery deterioration detection method according to claim 1,
In the current comparison step, a battery that calculates an integrated value difference between the integrated value of the estimated charge / discharge current and the integrated value of the actually measured charge / discharge current and compares the integrated value difference with a preset predetermined integrated value difference Degradation detection method. The battery deterioration detection method according to claim 9 or 11,
The current comparison step calculates an integrated value difference between the integrated value of the estimated charge / discharge current and the integrated value of the actually measured charge / discharge current, and a change amount of the integrated value difference and a preset predetermined integrated value difference change amount The battery deterioration detection method which compares. The battery deterioration detection method according to claim 9,
The current comparing step calculates a current difference integrated value of a current difference between the estimated charge / discharge current and the measured charge / discharge current, and compares the current difference integrated value with a predetermined current difference integrated value set in advance. Degradation detection method. The battery deterioration detection device according to claim 9 or 13,
The current comparing step calculates a current difference integrated value of a current difference between the estimated charge / discharge current and the measured charge / discharge current, and compares the current difference integrated value with a predetermined current difference integrated value set in advance. Degradation detection method. The battery deterioration detection method according to claim 9,
The current comparison step is a battery deterioration detection method in which a current ratio between the estimated charge / discharge current and the measured charge / discharge current is calculated, and the current ratio is compared with a predetermined current ratio set in advance. The battery deterioration detection method according to any one of claims 9 to 15,
The estimated charge / discharge current calculation step is a battery deterioration detection method in which an estimated charge / discharge current is calculated by the following formula (1).
I _n = (V−V _OCVn−1 ) / R _n (1)
(Where I _n represents the estimated charge-discharge current, V is the measured voltage, V _OCVn-1 are open circuit voltage, the R _n internal resistance.)

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