Electricity: battery or capacitor charging or discharging – Battery or cell discharging – With charging
Reexamination Certificate
2000-04-21
2001-03-13
Tso, Edward H. (Department: 2838)
Electricity: battery or capacitor charging or discharging
Battery or cell discharging
With charging
Reexamination Certificate
active
06201373
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a battery remaining capacity measuring apparatus, more particularly to a battery remaining capacity measuring apparatus wherein the quantity of collected samples for battery current and voltage and the quantity of samples for obtaining averages thereof are determined depending on a discharging time of the battery.
2. Description of the Related Art
Generally, measurement of the battery remaining capacity of an electric automobile is premised that discharge is continued for at shortest 10 seconds as shown in FIG. 7 by keeping an accelerator pressed, as described in Japanese Patent Application Laid-Open No.H8-62310.
In the battery remaining capacity measuring apparatus disclosed in Japanese Patent Application Laid-Open No.H8-62310, discharge current I and voltage V from the battery are sampled every 1 millisecond, and each time when 100 units (N
1
) of this current value and voltage value of 1 millisecond are collected, those values are averaged so as to obtain average data. When 100 units (N
2
) of this average data (N
1
×N
2
=10000) are obtained, a correlation between current and voltage is obtained. When a strong negative correlation is indicated, an approximate line (Y=a·X+b Y: current, X: voltage) is obtained based on the 100 average data. Then, by substituting a specified value for Y in this equation, the voltage X is specified so as to regard this voltage as current remaining capacity. That is, the remaining capacity is obtained based on data obtained by measuring for 10 seconds.
Because the quantity of data is very massive, even when current data in a charging direction for a short time exists, this can be buried as an error.
However, recently, a high voltage vehicle called hybrid car or simple hybrid car has been used which contains two kinds of driving sources, namely an engine and a DC motor and is driven by an engine or DC motor.
In such a hybrid car, recharge and discharge to the battery are repeated frequently. Therefore, the quantity of current data in the recharging direction increases so that this cannot be neglected as an error.
Particularly at the time of regenerative charge during a traveling of a vehicle or generative charge with an alternator, charging current to the battery is not constant (constant voltage charge), so that the correlation between current and voltage is reduced.
That is, the aforementioned method in which each time when 100 (N
1
) units of data comprised of current value and voltage value of 1 millisecond are collected, those values are averaged so as to obtain average data and then when 100 (N
2
) units (N
1
×N
2
=10000) of this average data are obtained, a remaining capacity is obtained with the obtained current and voltage, cannot be applied to measurement of the remaining capacity of the hybrid car because the correlation therebetween is small when no specific measure is taken.
SUMMARY OF THE INVENTION
The present invention has been achieved in views of the above problems and therefore, an object of the present invention is to provide a battery remaining capacity measuring apparatus capable of measuring a remaining capacity of a battery at a high accuracy in a hybrid car in which recharge and discharge to the battery are repeated frequently.
To achieve the above object, there is provided a battery remaining capacity measuring apparatus comprising: a voltage sensor for detecting a terminal voltage of a battery connected to a load; a current sensor for detecting a current flowing from the battery to the load; a collecting means for collecting a voltage value detected by the voltage sensor and a current value detected by the current sensor every predetermined time; a first determining means for determining whether or not a predetermined number of pairs of the voltage values and the current values are collected; a processing means for when the predetermined number of the plural pairs are collected, averaging the voltage values and the current values respectively so as to obtain a pair of an average voltage value and average current value and repeating the processing for obtaining the pair of the average voltage value and average current value; a second determining means for determining whether or not the processing by the processing means is continued in the shortest time from beginning of discharge from the battery to termination thereof; a means for when it is determined that the processing by the processing means is continued in the shortest time, obtaining a correlation value between voltage and current based on plural pairs of the average voltage values and the average current values; a means for when the correlation value indicates a stronger correlation than a predetermined level, obtaining an approximate line on current-voltage coordinate system based on the plural pairs of the average voltage values and the average current values; and an estimating means for estimating a remaining capacity of the battery by obtaining a corresponding voltage value based on the approximate line and a preliminarily set current value.
According to the present invention, because the battery remaining capacity is measured based on data of the shortest time from beginning of discharge of the battery to termination thereof, even when discharge and recharge to the battery are repeated frequently, an accurate remaining capacity is always obtained. When the data obtaining time is over both the discharge time and recharge time, correlation between a voltage value and a current value weakens so that the remaining capacity cannot be obtained. However a case based on only discharge time data is always generated because the measurement is based on the aforementioned shortest time data.
According to a preferred embodiment of the present invention, the load is hybrid mechanism for assisting a traveling with an engine and a motor and the battery is electrically connected to the motor.
For example, in the hybrid car whose traveling is assisted by an engine and a motor, the battery which is a driving source for that motor repeats discharge and recharge frequently. Even as to a battery in the hybrid car which repeats discharge and recharge frequently, the remaining capacity thereof is able to be meatured accurately.
According to another preferred embodiment of the present invention, where the shortest time is T
dc
(second), a collecting period by the collecting means is T
sa
(second) and the predetermined number of pairs of the voltage values and the current values is N
1
, a quantity N
2
of the plural pairs of the average voltage values and the average current values is obtained according to a following equation;
N
2
=
T
dc
(second)/(
T
sa
(second)×
N
1
)
According to this embodiment, as long as the above equation is satisfied, the collecting period T
sa
(second) by the collecting means, quantity N
1
of the predetermined number of pairs the voltage values and the current values and quantity N
2
of plural pairs of the average voltage values and average current values can be determined arbitrarily.
According to still another preferred embodiment of the present invention, the shortest time T
dc
is 0.8 seconds.
Further, according to still another preferred embodiment of the present invention, the collecting period T
sa
is 0.001 seconds and the N
1
is 8.
The nature, principle and utility of the invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings.
REFERENCES:
patent: 5561362 (1996-10-01), Kawamura et al.
patent: 5617324 (1997-04-01), Arai
patent: 5698983 (1997-12-01), Arai et al.
patent: 5703486 (1997-12-01), Arai et al.
patent: 5789923 (1998-08-01), Shimoyama et al.
patent: 5798934 (1998-08-01), Saigo et al.
patent: 5898292 (1999-04-01), Takemoto et al.
patent: P 8-62310 (1996-03-01), None
patent: P 10-246760 (1998-09-01), None
Arai Youchi
Enomoto Michito
Saigo Tsutomu
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Tso Edward H.
Yazaki -Corporation
LandOfFree
Battery remaining capacity measuring apparatus suitable for... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Battery remaining capacity measuring apparatus suitable for..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Battery remaining capacity measuring apparatus suitable for... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2542366