JPH07263034A - Battery condition judging device - Google Patents

Abstract

PURPOSE:To always accurately know a battery working limit even if dispersion of reference capacity of a battery or the degradation with the lapse of time or a variation in a discharge current or the like is caused. CONSTITUTION:A battery condition judging device has a voltage detecting circuit 5 to detect terminal voltage of a battery and an electric current detecting circuit 6 to detect a charge-discharge current of the battery, and an operation circuit 8 calculates a battery residual capacity index related to a value by subtracting a charge-discharge quantity from a reference capacity value of the battery, and calculates battery electric power consumption from the terminal voltage and the charge-discharge current. The chargedischarge current of the battery is estimated as the battery-residual capacity index and a function of the battery electric power consumption, and the charge-discharge current is estimated in order in a prescribed electric power consumption pattern, and the battery residual capacity index is calculated in order from this estimated charge-discharge current. Time when the battery discharge current estimated according to a renewed battery residual capacity index exceeds a limiting current in electric power consumption at this time, is judged as a battery working limit, and is displayed by a display circuit 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery state determination device, and more particularly to a determination device used for detecting the state of charge of a battery and promoting recharging.

[0002]

2. Description of the Related Art The state of charge of a battery is known, for example, by subtracting the integrated value of discharge current, that is, the discharge amount from the full charge capacity. However, this shows the remaining capacity relatively accurately when discharged at a constant current, but when the current consumption of the battery fluctuates greatly depending on the running state of the vehicle, such as in an electric vehicle, The method cannot accurately determine the remaining capacity of the actually usable battery.

Therefore, for example, in Japanese Unexamined Patent Publication No. 4-368401, the battery utilization factor is calculated from the battery temperature and the discharge current, and the present remaining amount is calculated from the last remaining capacity, the utilization factor for this remaining capacity, and the discharge current during this period. A device for knowing capacity is shown.

[0004]

However, the actual vehicle drive battery has variations in its characteristics, and
The remaining capacity obtained last time will change due to many factors during the use process, such as deterioration. Therefore, with the device described in the above publication, it has not been possible to accurately determine the usage limit at which battery recharging is required.

SUMMARY OF THE INVENTION The present invention solves such a problem by providing a battery state determining device capable of always accurately knowing the battery usage limit even if there are variations in the reference capacity of the battery, deterioration over time, fluctuations in discharge current, and the like. The purpose is to provide.

[0006]

According to another aspect of the present invention, there is provided a voltage detecting means for detecting a terminal voltage of a battery, a current detecting means for detecting a charging / discharging current of the battery, and a charging / discharging operation based on a reference capacity value of the battery. Remaining capacity index calculating means for calculating a remaining capacity index of the battery related to the value obtained by subtracting the amount, power consumption calculating means for calculating battery power consumption from the terminal voltage and charging / discharging current, the remaining capacity index of the battery and the battery Charge / discharge current estimation means for estimating the charge / discharge current of the battery as a function of power consumption, and a predetermined power consumption pattern is given to the charge / discharge current estimation means to sequentially estimate the charge / discharge current, and the estimated charge / discharge current The battery remaining capacity index is sequentially calculated by giving it to the remaining capacity index calculating means, and the battery discharge estimated based on the updated battery remaining capacity index. Flow is provided with a determination unit that the battery use limit when exceeding the limiting current under the power consumption at this time. In the configuration of claim 2, the charge / discharge current is set so as to maximize or minimize the evaluation function relating to the difference between the charge / discharge current estimated by the charge / discharge current estimation means and the charge / discharge current detected by the current detection means. It further comprises coefficient correction means for correcting the coefficient of the estimation formula in the estimation means. According to the third aspect of the present invention, the distance detection means for detecting the distance traveled by the host vehicle within a certain time period ahead of the present time, the means for storing the power consumption pattern during this time, and the above-mentioned usage limit at the time of this memory consumption pattern are reached. Display means is further provided for calculating and displaying a possible traveling distance from time. In the configuration of claim 4, the voltage detecting means for detecting the terminal voltage of the battery, the current detecting means for detecting the charging / discharging current of the battery, and the battery related to the value obtained by subtracting the discharge amount from the reference capacity value of the battery. Remaining capacity index calculating means for calculating the remaining capacity index, power consumption calculating means for calculating battery power consumption from the terminal voltage and discharge current, and battery charging / discharging current as a function of the battery remaining capacity index and battery power consumption. The charging / discharging current estimating means for estimating, the charging / discharging current in order to maximize or minimize the evaluation function relating to the difference between the charging / discharging current estimated by the charging / discharging current estimating means and the charging / discharging current detected by the current detecting means. A coefficient correction means for correcting the coefficient of the estimation formula in the estimation means, and the battery capacity is calculated from the battery remaining capacity index calculated by the remaining capacity index calculating means. We know the use limit. In the configuration of claim 5, the battery remaining capacity index calculated by the remaining capacity index calculating means is calculated by comparing the charging / discharging current estimated by the charging / discharging current estimating means and the charging / discharging current detected by the current detecting means. A remaining capacity index correcting means for correcting with a correction amount proportional to the difference is further provided. In the configuration of claim 6, the voltage detecting means for detecting the terminal voltage of the battery, the current detecting means for detecting the charge / discharge current of the battery, and the battery related to the value obtained by subtracting the discharge amount from the reference capacity value of the battery. Remaining capacity index calculating means for calculating the remaining capacity index, power consumption calculating means for calculating battery power consumption from the terminal voltage and discharge current, and battery charging / discharging current as a function of the battery remaining capacity index and battery power consumption. The charging / discharging current estimating means for estimating and the battery remaining capacity index calculated by the remaining capacity index calculating means are set to the difference between the discharging current estimated by the charging / discharging current estimating means and the discharging current detected by the current detecting means. The remaining capacity index correction means for correcting with a proportional correction amount, and a value obtained by adding the correction amount to the battery reference capacity value are predetermined with respect to the battery reference capacity value. Are provided with a determination unit that the battery use limit when Percentage below. In the structure of claim 7, temperature detecting means for detecting the battery temperature is further provided, and the battery reference capacity value in the remaining capacity index calculating means is corrected by the battery temperature. In the structure of claim 8, the remaining capacity index calculating means is set to weight the discharge current used for calculating the discharge amount according to the current value. According to the ninth aspect of the present invention, the charging / discharging pause correcting means for correcting the battery remaining capacity index calculated by the remaining capacity index calculating means based on the battery capacity recovery value during charging / discharging suspension is further provided. In the structure of claim 10,
Data storage means for storing data of battery charging / discharging current, battery temperature, and battery voltage, and optimization for optimizing the estimation formula in the charging / discharging current estimating means from the data stored in the data storage means after the end of traveling of the vehicle Means are further provided.

[0007]

In the above structure, the charging / discharging current estimating means estimates the battery charging / discharging current as a function of the battery remaining capacity index and the battery power consumption, and the battery discharging current under a predetermined power consumption pattern is calculated. At this time, when it exceeds the limit current under the power consumption, it is determined that the battery usage limit, so the discharge current fluctuates greatly,
Alternatively, even if the battery deteriorates with time, the battery usage limit can always be accurately determined. In the configuration of claim 4, the charge / discharge current estimation is performed in order to maximize or minimize the evaluation function relating to the difference between the charge / discharge current estimated by the charge / discharge current estimation means and the charge / discharge current detected by the current detection means. By providing a coefficient correction means for correcting the coefficient of the estimation formula in the means, the battery usage limit can be accurately known from the battery remaining capacity index calculated by the remaining capacity index calculating means at this time. In the configuration of claim 6, the battery remaining capacity index calculated by the remaining capacity index calculating means is proportional to the difference between the discharge current estimated by the charge / discharge current estimating means and the discharge current detected by the current detecting means. The discharge current fluctuates greatly because the battery usage limit is determined when the value obtained by adding the above correction amount to the battery reference capacity value is less than or equal to the predetermined ratio to the battery reference capacity value. However, even if the battery deteriorates over time, the battery usage limit can always be accurately determined. In the structure of claim 3, when the vehicle is mounted, the travelable distance of the vehicle can be easily known. Claim 2,
In the configurations of 5, 7, 8, 9, and 10, various corrections or optimizations can be performed to more accurately determine the battery usage limit.

[0008]

[Embodiment 1] In FIG. 1, a battery 1 has a charger 2
And the electric load 4 is connected via the load control device 3. A circuit 5 for detecting a battery terminal voltage, a circuit 6 for detecting a discharging current from the battery 1 to the electric load 4 or a regenerative charging current from the electric load 4, a circuit 7 for detecting a battery temperature, and the like are provided. further,
An arithmetic circuit 8, a memory circuit 9, and a display circuit 10 are provided,
The operation described below is performed. The arithmetic circuit 8 and the like can be realized by a microcomputer.

The storage circuit 9 stores a battery characteristic equation as an estimation equation, and its basic form is shown in the equation. The storage circuit 9 also stores data of the detected battery terminal voltage and the like for a certain period of time. Ir = Wat (A ・ Sok + B ・ So + C ・ Wat +
D) ... Ir '= Wat (A'.Sok' + B'.So + C '.
Wat + D ') ...' Here, Ir is the estimated discharge current, A, B, C, D are coefficients,
Ir 'is an estimated charging current, A', B ', C', D'are coefficients, Wat is a power consumption (W) per battery, and k = 30 and k '= 2 in the case of a sealed lead-acid battery. is there.
The above-mentioned So is represented by a formula, and SOC> 100
Then, So = 0. So = 1-SOC / 100 ... The above SOC is a 0.2 CA conversion remaining capacity index (%) of the battery, and is represented by a formula. SOC = {(Aho · Kt−Σi · Kidt) / Aho
+ Α) × 100 (%) ... where Aho is the reference capacity (5-hour rate capacity), i is the output current including both charging and discharging currents, Kt is the temperature correction coefficient,
Ki is a current correction coefficient, and α is a battery capacity recovery value in a charge / discharge pause state. FIG. 2 shows the relationship between the battery case temperature and the temperature correction coefficient Kt, and FIG. 3 shows the relationship between the discharge current and the current correction coefficient. Further, the battery capacity recovery value α is expressed by an equation. α = Σidt + (Σi · Kidt−Σidt) exp
(-T / Tk) ... Here, t is a charging pause time and Tk is a constant.

As shown in FIG. 4, the coefficient of the characteristic equation is the power consumption based on the detection data (step 101) such as the battery terminal voltage, the charging / discharging current and the battery temperature obtained from the constant current charge / discharge test, the constant power discharge test and the like. Wat, 0.2CA
The converted remaining capacity index S0C is calculated (step 102),
The estimated discharge current Ir and the estimated charge current Ir 'are obtained by substituting this into the battery characteristic equation (equation and equation') (step 103). Then, the estimated discharge current Ir and the estimated charge current Ir 'are compared with the actual detected current Id, and the optimum coefficients A, B, C, and B of the battery characteristic equation are set so that the mean square error J of the equation is minimized. D, A ', B', C ', D'
Is calculated (step 104). J = √Σ (Ir−Id) ² / ΣId ² ...

In the arithmetic circuit 8, the procedure shown in FIG.
A correction amount β for correcting the 0.2 CA converted remaining capacity index SOC is calculated. That is, in step 201, data such as battery terminal voltage, discharge current, and battery temperature are detected, and in step 202, SOC and power consumption Wat are calculated. These are substituted into the battery characteristic formula (formula) to obtain the estimated discharge current Ir (step 203), and this and the detected current I
The difference (Ir-Id) of d is multiplied by the correction attenuation coefficient Kβ to obtain the correction amount β (step 204). This correction amount β is S
It is fed back to the calculation (formula) of OC, and the SOC value is corrected by the following formula. SOC = {(Aho · Kt−Σi · Kidt + β) / A
ho + α) × 100 (%) …… By making such a correction, the correct SO when using this time is obtained.
C can be obtained, and the estimation accuracy of the battery usable amount can be improved. Further, it is clear from the above equation that accurate values of the temperature correction coefficient Kt and the current correction coefficient Ki are not required by performing this correction,
The SOC can be accurately calculated even if the battery characteristics change.

Now, in the display circuit 10 (FIG. 1), a predetermined use pattern stored in the storage circuit 9 in advance (for example, power consumption every Δt seconds during 10 mode running) and SOC calculated from the detection data are displayed. Based on the above equation, the estimated discharge current Ir or the estimated charge current Ir 'is calculated from the above equation'. At the same time, the battery terminal voltage is estimated by dividing the power consumption Wat at this time by the estimated discharge current Ir or the estimated charge current Ir '. Then, the estimated discharge current Ir or the estimated charge current Ir 'is used as the discharge current i in the equation to calculate the corrected SOC. Repeat this calculation to determine SOC
Then, the estimated discharge current is sequentially calculated, and the time when the estimated battery terminal voltage becomes equal to or lower than a predetermined voltage (discharge end voltage) predetermined for each discharge current is obtained. Here, the discharge end voltage is a discharge stop voltage that should be avoided for maintenance of the battery electrode plate, and the above time indicates a battery usable time when the battery is used in the future in a predetermined use pattern. .

The effect of this embodiment is shown in FIG. The line x in the figure shows the actual usable time of the battery when the battery charge / discharge test is performed using the power value simulating the 10-mode running as the command value. The line y is the calculated usable time without correcting the SOC, and shows a tendency along with the actual usable time. However, if the battery reference capacity varies, a constant error is shown as shown in the figure. Is occurring. On the other hand, when the SOC is corrected, as shown by the line z, even if there is a variation in the reference capacitance, the actual usable time gradually coincides with accuracy as the sequential calculation proceeds.

In the present embodiment, the battery usable time may be calculated on the assumption that the usage pattern within the past fixed time is continued instead of the predetermined usage pattern.

Similar results can be obtained by detecting that the battery discharge current exceeds a predetermined limit current, instead of detecting that the discharge end voltage becomes a predetermined voltage or less.

It goes without saying that other evaluation functions can be used in place of the root mean square error J of the formula, and if the estimation accuracy of the usable time is sufficient, the coefficient correction of the battery characteristic formula by the evaluation function is possible. Is not particularly necessary.

Instead of calculating the usable time, the battery remaining capacity may be determined by the value of the battery remaining capacity index SOC.

Further, instead of calculating the usable time, when the value (Aho + β) obtained by adding the correction amount β to the battery reference capacity value Aho is lower than, for example, 80% of Aho, the battery use limit is determined. You can also

If the estimation accuracy of the usable time is sufficient,
The correction based on the temperature correction coefficient Kt, the current correction coefficient Ki, the battery capacity recovery value α in the charge / discharge pause state, etc. is not particularly necessary.

[0020]

[Embodiment 2] As shown in FIG. 7, in addition to the configuration of Embodiment 1 described above, a traveling distance detection circuit 11 for a vehicle is provided. As a result, the average traveling distance within a certain period of time prior to the present is calculated, and when the vehicle travels further in this traveling pattern, the display circuit 10 displays the traveling distance within the usable time.

[0021]

Third Embodiment As shown in FIG. 8, in addition to the configuration of the first embodiment, a detection data storage circuit 12 and an optimization circuit 13 are provided. The optimization circuit 13 uses the storage circuit 12 while the vehicle is traveling.
Based on the detection data such as the battery terminal voltage stored in
In the same manner as the method shown in FIG. 4 described above, the battery characteristic formula (formula, formula ') is reconstructed after the vehicle travels. As a result, the characteristic equation showing the latest battery characteristic is rewritten, the burden of the correction amount β of the equation is reduced, and the estimated time of battery availability can quickly coincide with the actual time.

[0022]

As described above, according to the battery state determination device of the present invention, the battery usage limit can always be accurately known even if there is variation in the reference capacity of the battery, deterioration over time, or variation in the discharge current. it can.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of an apparatus according to a first embodiment of the present invention.

FIG. 2 is a graph showing a relationship between a battery case temperature and a temperature correction coefficient.

FIG. 3 is a graph showing the relationship between discharge current and current correction coefficient.

FIG. 4 is a flowchart showing a processing procedure in an arithmetic circuit.

FIG. 5 is a flowchart showing a processing procedure in an arithmetic circuit.

FIG. 6 is a graph showing the effect of using the device of the present invention.

FIG. 7 is a block configuration diagram of an apparatus according to a second embodiment of the present invention.

FIG. 8 is a block configuration diagram of an apparatus according to a third embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Battery 3 Load control device 4 Electric load 5 Battery terminal voltage detection circuit (voltage detection means) 6 Discharge / charge current detection circuit (current detection means) 7 Battery temperature detection circuit (temperature detection means) 8 Operation circuit (remaining capacity index calculation) Means, power consumption calculation means, charge / discharge current estimation means, determination means, coefficient correction means, remaining capacity index correction means, charge / discharge pause correction means) 9 memory circuit 10 display circuit (display means) 11 mileage detection circuit (distance detection Means) 12 detection data storage circuit (data storage means) 13 optimization circuit (optimization means)

Claims (10)

[Claims] 1. A voltage detecting means for detecting a terminal voltage of a battery, a current detecting means for detecting a charging / discharging current of the battery, and a remaining capacity index of the battery related to a value obtained by subtracting a discharge amount from a reference capacity value of the battery. A remaining capacity index calculating means, a power consumption calculating means for calculating the battery power consumption from the terminal voltage and the discharge current, and a discharge estimating the charging / discharging current of the battery as a function of the battery remaining capacity index and the battery power consumption. A current estimation means and a predetermined power consumption pattern are given to the discharge current estimation means to estimate a sequential charge / discharge current, and the estimated charge / discharge current is given to the remaining capacity index calculation means to sequentially calculate a battery remaining capacity index. When the battery discharge current estimated based on the updated battery remaining capacity index exceeds the limit current under the power consumption at this time, And a battery state determining device including a determining unit that determines the battery usage limit. 2. The estimation in the discharge current estimating means in order to maximize or minimize the evaluation function relating to the difference between the charge / discharge current estimated by the charge / discharge current estimating means and the charge / discharge current detected by the current detecting means. The battery state determination device according to claim 1, further comprising coefficient correction means for correcting the coefficient of the equation. 3. A distance detection means for detecting the distance traveled by the host vehicle within a fixed time prior to the present time, a means for storing a power consumption pattern in the meantime, and a time to reach the above-mentioned usage limit in the stored power consumption pattern. The battery state determination device according to claim 1 or 2, further comprising display means for calculating and displaying a possible running distance in the future. 4. A voltage detecting means for detecting a terminal voltage of the battery, a current detecting means for detecting a charging / discharging current of the battery, and a remaining capacity of the battery related to a value obtained by subtracting the charging / discharging amount from a reference capacity value of the battery. Remaining capacity index calculating means for calculating an index, power consumption calculating means for calculating battery power consumption from the terminal voltage and charging / discharging current, and estimating battery charging / discharging current as a function of the battery remaining capacity index and battery power consumption Charging / discharging current estimating means, in order to maximize or minimize the evaluation function relating to the difference between the discharging current estimated by the charging / discharging current estimating means and the discharging current detected by the current detecting means, in the charging / discharging current estimating means A coefficient correction means for correcting the coefficient of the estimation formula, and knows the battery usage limit from the battery remaining capacity index calculated by the remaining capacity index calculating means. A battery state determination device characterized by: 5. The battery remaining capacity index calculated by the remaining capacity index calculating means is corrected in proportion to the difference between the discharge current estimated by the charge / discharge current estimating means and the discharge current detected by the current detecting means. The battery state determination device according to any one of claims 1 to 4, further comprising a remaining capacity index correction unit that corrects by a quantity. 6. A voltage detecting means for detecting a terminal voltage of the battery, a current detecting means for detecting a charging / discharging current of the battery, and a remaining capacity of the battery relating to a value obtained by subtracting the charging / discharging amount from a reference capacity value of the battery. Remaining capacity index calculating means for calculating an index, power consumption calculating means for calculating battery power consumption from the terminal voltage and discharge current, and discharge for estimating battery discharge current as a function of the battery remaining capacity index and battery power consumption The battery remaining capacity index calculated by the current estimation means and the remaining capacity index calculation means is a correction amount proportional to the difference between the discharge current estimated by the discharge current estimation means and the discharge current detected by the current detection means. The remaining capacity index correcting means for correcting and the value obtained by adding the correction amount to the battery reference capacity value are below a predetermined ratio with respect to the battery reference capacity value. A battery state determination device, which sometimes comprises a determination means for determining a battery usage limit. 7. The temperature detecting means for detecting the battery temperature is further provided, and the battery reference capacity value in the remaining capacity index calculating means is corrected by the battery temperature. Battery state determination device. 8. The remaining capacity index calculating means is set to weight the discharge current used for calculating the discharge amount according to the current value. Battery state determination device. 9. The charging / discharging suspension correcting means for correcting the battery remaining capacity index calculated by the remaining capacity index calculating means on the basis of the battery capacity recovery value during charging / discharging suspension, according to any one of claims 1 to 8. The battery state determination device described. 10. A battery charging / discharging current, a battery temperature,
The data storage means for storing the data of the battery voltage, and the optimization means for optimizing the estimation formula in the charging / discharging current estimation means from the data stored in the data storage means after the end of traveling of the vehicle are further provided. 10. The battery state determination device according to any one of 9 to 9.