JP3767150B2 - Battery remaining capacity detection device - Google Patents

Battery remaining capacity detection device Download PDF

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Publication number
JP3767150B2
JP3767150B2 JP01488698A JP1488698A JP3767150B2 JP 3767150 B2 JP3767150 B2 JP 3767150B2 JP 01488698 A JP01488698 A JP 01488698A JP 1488698 A JP1488698 A JP 1488698A JP 3767150 B2 JP3767150 B2 JP 3767150B2
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Prior art keywords
remaining capacity
battery
voltage
value
current
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JPH11206028A (en
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雄児 丹上
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Nissan Motor Co Ltd
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Nissan Motor Co Ltd
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    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10Energy storage using batteries

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  • Measurement Of Current Or Voltage (AREA)
  • Tests Of Electric Status Of Batteries (AREA)
  • Charge And Discharge Circuits For Batteries Or The Like (AREA)

Description

【0001】
【発明の属する技術分野】
本発明は、電池の残存容量検出装置に関する。
【0002】
【従来の技術】
従来の電池の残存容量検出には、例えば特開平4−368401号公報や特開平6−174808号公報に示すようなものがある。前者に記載されたものでは、電池に流れる電流値の積算値に基づいて残存容量を求める。また後者のものでは、電池の電圧値と電池に流れる電流値より開放電圧を推定し、この開放電圧に基づいて残存容量を求めるようにしている。
【0003】
【発明が解決しようとする課題】
しかしながら、上記従来の電池の残存容量検出装置のうち、前者の電池に流れる電流値を積算して電池の残存容量を検出するものにおいては、電流検出器の誤差が蓄積されるため、長時間使用すると精度が低下してくるという不都合がある。
また、後者の電池電圧値と電池に流れる電流値より開放電圧を算出して行うものにおいては、電池の残存容量を算出するタイミングによって算出結果が異なってくるため、すべての使用条件において電池の残存容量を精度良く検出することが困難であるという問題がある。とくに図6に示すように、電流値が正(放電)側ばかりの領域で取得した電流値から開放電圧を算出した場合などには推定される開放電圧の振れ幅が大きく、精度が低下することになる。
【0004】
したがって、本発明は、このような従来の問題点に着目してなされたもので、電池の残存容量をより精度良く求めることのできる残存容量検出装置を提供することを目的とする。
【0005】
【課題を解決するための手段】
このため本発明は、電池の電圧値と電池に流れる電流値とを検出する電池電圧値・電流値検出手段と、検出された電圧値と電流値から電池の開放電圧を算出する開放電圧算出手段と、開放電圧に基づいて電池の残存容量を求める第1の残存容量検出手段とを有する電池の残存容量検出装置において、開放電圧算出手段が、上記電流値が正から負に変化しまたは負から正に変化したときの電圧値と当該電流値とから充放電I−V特性線を求め、その充放電I−V特性線上で電池の開放電圧を算出するものとした。
【0006】
さらに、上記の電池電圧値・電流値検出手段で検出された電流値の積算値に基づいて電池の残存容量を求める第2の残存容量検出手段と、比較手段、および切り替え手段とを有して、電池の使用当初は前記第2の残存容量検出手段で求めた残存容量を出力とし、上記第1の残存容量検出手段と第2の残存容量検出手段でそれぞれ求めた残存容量を比較し、それぞれの残存容量の差が所定値以上になると、残存容量を第1の残存容量検出手段で求めた残存容量に切り替えて出力することができる。
【0007】
上記の残存容量は表示装置に出力することができ、また、充放電I−V特性線を基に算出した電池の入出力可能電流も残存容量とともに表示装置に出力することができる。
【0008】
【作用】
電池の電流が負(充電)から正(放電)に変化したとき、または正(放電)から負(充電)に変化したときの電圧値および電流値から充放電I−V特性を算出するので、開放電圧の触れが小さく、この精度の良い開放電圧を基に電池の残存容量を求めることができる。
また、電池の使用開始当初は出力として電流値の積算値から求めた残存容量を用いながら、開放電圧を基に求めた残存容量とを比較してその差が所定値より大きくなったら開放電圧を基に求めた残存容量を用いることにより、使用経過時間を通じて精度の良い残存容量を得ることができる。
【0009】
【発明の実施の形態】
本発明の実施の形態を実施例により説明する。
図1は、本発明をハイブリッド電気自動車のモータの駆動用電池の残存容量検出に適用した実施例を示すブロック図である。
ハイブリッド電気自動車は、駆動源としてエンジン(ENG)1とモータ(MTR)10とを備えている。エンジン1は車両の駆動源であると同時に、発電機(GEN)2の駆動源でもある。すなわち、エンジン1の出力軸は発電機2に直接または間接に接続されており、エンジン1が回転すると発電機2からは発電電力が出力される。したがって、エンジン1と発電機2はエンジン駆動発電機を構成している。
発電機2の出力は、整流器3によって直流電力に変換され、充放電可能なリチウムイオン電池(以下、単に電池と呼ぶ)5に供給される。
【0010】
車両コントローラ11は、運転者のアクセル操作やブレーキ操作等を示す車両信号とともに、電池コントローラ8からの電池状態を示す信号を入力し、インバータ(INV)9の動作を制御する。電池コントローラ8にはまた表示装置12が接続されている。
【0011】
電池コントローラ8は、電流検出器6および電圧検出器7により、それぞれ検出された電池5の充放電電流と端子間電圧を入力し、これらの値から電池状態を表す信号を算出し、所定の条件が満たされた場合に発電コントローラ4を介してエンジン駆動発電機の発電を開始させる。
【0012】
電池コントローラ8は、所定のサンプリング時間毎に電流検出器6および電圧検出器7によりそれぞれ電池5に流れる電流値および端子電圧値を検出し、検出された電池に流れる電流が負(充電)から正(放電)に変化したとき、または正(放電)から負(充電)に変化したときに、充放電I−V特性線を求める。
また、充放電I−V特性線を基に最大放電可能電流および最大受入可能電流を算出する。 そして、
最大放電可能電流≦最大受入可能電流
のときにエンジン駆動発電機の発電を開始する。
【0013】
図2は、充放電I−V特性(線)を示す図である。電流に平行な上方の破線は電池の満充電電圧すなわち最大電圧Vmaxを示し、下方の破線は電池の放電下限電圧すなわち最小電圧Vminを示す。
図中、斜線が最大電圧Vmaxを示す線に達した点が最大受入可能電流Icであり、最小電圧Vminを示す線に達した点に対応する電流軸上の点が最大放電可能電流Idである。
最大放電可能電流と最大受入可能電流、すなわち入出力可能電流から入出力パワーを求めることができる。
【0014】
発電コントローラ4は、エンジン駆動発電機を動作させている場合に、エンジン1の回転数や発電機2の出力電圧、電流をモニタして、発電機2の出力電圧が一定となるように制御する。
【0015】
図3は、電池コントローラ8における電池残存容量算出表示の制御動作を示すフローチャートである。
ステップ101では、ハイブリッド電気自動車の運行、すなわち電池5の使用開始にあたって、電圧検出器7により電池5の開放電圧を検出し、その開放電圧を基に電池5の残存容量を算出して初期値とする。ここでは、あらかじめ定まっている残存容量と開放電圧の関係から、残存容量が求められる。図4はリチウムイオン電池の場合における残存容量と開放電圧の関係例を示す。この図より、電池の開放電圧が求まれば残存容量を求めることが可能である。
【0016】
ハイブリッド電気自動車の運行中は、ステップ102において、電池5に流れる電流(充電電流)と電池電圧(端子電圧)を所定のサンプリング時間毎に電流検出器6および電圧検出器7により検出する。
ステップ103では、ステップ102で検出したサンプリング電流値を積算することにより残存容量を算出する。
残存容量の算出は、電流積算値を電池5の定格容量で除算することにより求めることができる。
そして次のステップ104で、上記電流積算値から求めた残存容量を表示装置12に表示する。
【0017】
ステップ105では、電流検出器6で検出した電流値が負(充電)から正(放電)に変化したとき、または正(放電)から負(充電)に変化したときのサンプリング電流値および電圧値を基に、電池コントローラ8において充放電I−V特性を求める。
【0018】
電池の充放電I−V特性は、先の図2に示すように、電流値の増加に伴い電圧が直線的に減少する特性線として表わされる。
なお、充放電I−V特性線は電流値が正負の間を変化した2点のサンプリング値から求めることもできるが、あらかじめ定められた放電を開始する電圧値または充電を開始する電圧値近傍を検知したとき所定時間毎にサンプリングし、その検出された複数の充・放電電流Iと端子電圧Vの値を、縦軸を電圧軸、横軸を電流軸としたグラフ上にプロットして、例えば最小二乗法により直線近似することによっても得られる。
【0019】
ステップ106では、充放電I−V特性線から開放電圧を算出する。開放電圧は、直線近似した斜線と電圧軸(Y軸)との交点の電圧値として求められる。
ステップ107では、図4の残存容量と開放電圧の関係マップを用いて、ステップ106で求めた開放電圧から残存容量を求める。
【0020】
ステップ108では、ステップ103において電流積算値から算出した残存容量と、ステップ107において開放電圧から求めた残存容量とを比較する。両残存容量の差が所定値以上であればステップ109へ進み、そうでなければステップ104へ戻り、電流積算値から求めた残存容量を表示装置12へ出力して表示させる。
一般的に、充放電を開始した直後は、電流積算値で求めた残存容量の方が精度良く求められる。
【0021】
一方、ステップ109では、残存容量の値として、ステップ103で電流積算値から求めた残存容量をステップ107で開放電圧から求めた残存容量に置き換える。
そしてステップ110において、変更結果である開放電圧から求めた残存容量を表示装置12に表示させる。なお、残存容量の表示と併せて、充放電I−V特性を基に算出される入出力可能電流も表示することができる。
【0022】
ここでは、上記のステップ101、102が発明の電池電圧値・電流値検出手段を構成し、ステップ105、106が開放電圧算出手段を、ステップ107が第1の残存容量検出手段を、ステップ103が第2の残存容量検出手段を、ステップ108が比較手段を、そして、ステップ109が切り替え手段を構成している。
【0023】
本実施例は以上のように構成され、電流値が負(充電)から正(放電)に変化し、または正(放電)から負(充電)に変化する領域でサンプリング検出しているため、電流値が負(充電)の点と正(放電)の点が必ず存在することになり、電流値がたとえば正(放電)側ばかりの領域で取得した電流値から開放電圧を算出した場合に比較して、誤差が小さく、開放電圧を精度良く算出することができる。
【0024】
図5は本実施例により求めた残存容量および従来方法により求めた残存容量の誤差を使用経過時間との関係で示すもので、Aは本実施例による残存容量の誤差、Bは従来の電流積算で残存容量を求めたときの誤差、そしてCは従来の所定時間間隔で開放電圧を算出して残存容量を求めた場合の誤差である。
電流積算値に基づいて求められる残存容量(B)は使用開始当初の精度が良いが、時間経過とともに誤差が大きくなっていく。これに対して従来の開放電圧から求める残存容量(C)は誤差の幅を或る程度で抑えられるが、使用開始当初の精度が(B)の場合よりも劣る。
実施例による(A)では、使用開始当初は電流積算値に基づいて(B)と同様の高精度を得ながら、所定時間経過後は、電流値が正と負にまたがる領域で算出した開放電圧に基づいた残存容量を表示するので、(C)よりも誤差範囲が小さく抑えられている。
【0025】
なお、上記説明では、リチウムイオン電池の残存容量と開放電圧の関係が温度や劣化度合いの影響をほとんど受けないので、電流積算値を電池5の定格容量で除算して残存容量を算出するものとしているが、電池5の種類によって電池温度を検出するようにしている場合には、電流積算値をその温度での電池容量で除算することにより残存容量を一層精度よく求められる。
【0026】
以上のように、本実施例によれば、充放電I−V特性線が正確に求められるので、電池使用開始当初は電流積算値から求めた残存容量を採用しながら、その後状況によって開放電圧に基づく精度のよい残存容量を表示することができる。
【0027】
ハイブリッド電気自動車の場合は、電池5を満充電あるいは完全放電することは少ないので、電流積算値を満充電や空の状態でリセットすることができず、一方で充放電を頻繁に繰り返す。したがって、開放電圧から残存容量を求めることが要求されることになるが、本実施例によれば、電流積算値による残存容量算出と開放電圧による残存容量算出とを組み合わせて、精度の良い残存容量を得ることができるので、ハイブリッド電気自動車にとってとくに効果的である。
【0028】
【発明の効果】
以上のとおり、本発明は、電池の電圧値と電流値から算出した開放電圧に基づいて電池の残存容量を求めるようにした残存容量検出装置において、開放電圧の算出に際して、電流値が正から負に変化しまたは負から正に変化したときの電圧値と当該電流値とから充放電I−V特性線を求め、該充放電I−V特性線上で電池の開放電圧を算出するものとしたので、開放電圧の触れが小さく、これを基に精度の良い電池の残存容量を得ることができる。
【0029】
また、電池の使用開始当初は出力として電流値の積算値から求めた残存容量を用いながら、開放電圧を基に求めた残存容量とを比較してその差が所定値より大きくなったら開放電圧を基に求めた残存容量を用いることにより、使用経過時間を通じて精度の良い残存容量を得ることができる。
【図面の簡単な説明】
【図1】本発明の実施例に係る電池の残存容量検出装置の構成を示す図である。
【図2】充放電I−V特性線を示す図である。
【図3】実施例の制御動作を示すフローチャートである。
【図4】電池の残存容量と開放電圧との関係を示すマップ図である。
【図5】実施例により求めた残存容量と比較例により求めた残存容量の誤差を使用経過時間との関係で示す説明図である。
【図6】従来例における開放電圧算出の問題点を示す説明図である。
【符号の説明】
1 エンジン
2 発電機
3 整流器
4 車両コントローラ
5 リチュームイオン電池
6 電流検出器
7 電圧検出器
8 電池コントローラ
9 インバータ
10 モータ
11 車両コントローラ
12 表示装置
[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a battery remaining capacity detection device.
[0002]
[Prior art]
Conventional battery remaining capacity detection includes, for example, those disclosed in Japanese Patent Laid-Open Nos. 4-368401 and 6-174808. In the former, the remaining capacity is obtained based on the integrated value of the current value flowing through the battery. In the latter case, the open circuit voltage is estimated from the voltage value of the battery and the current value flowing through the battery, and the remaining capacity is obtained based on the open circuit voltage.
[0003]
[Problems to be solved by the invention]
However, among the above conventional battery remaining capacity detection devices, those that detect the remaining capacity of the battery by accumulating the current value flowing through the former battery accumulate the error of the current detector, so that they are used for a long time. Then, there is an inconvenience that accuracy decreases.
In addition, in the latter case where the open circuit voltage is calculated from the battery voltage value and the current value flowing through the battery, the calculation result varies depending on the timing of calculating the remaining capacity of the battery. There is a problem that it is difficult to accurately detect the capacity. In particular, as shown in FIG. 6, when the open-circuit voltage is calculated from the current value acquired only in the region where the current value is only on the positive (discharge) side, the estimated open-circuit voltage swing is large and the accuracy decreases. become.
[0004]
Accordingly, the present invention has been made paying attention to such a conventional problem, and an object of the present invention is to provide a remaining capacity detecting device capable of obtaining a remaining capacity of a battery with higher accuracy.
[0005]
[Means for Solving the Problems]
Thus the present invention, the open-circuit voltage calculation means for calculating a battery voltage value and current value detecting means for detecting a current flowing through the voltage value and the battery of the battery, the open circuit voltage of the battery from the detected voltage and current values And a first remaining capacity detecting device for determining the remaining capacity of the battery based on the open voltage, wherein the open circuit voltage calculating means changes the current value from positive to negative or from negative The charge / discharge IV characteristic line was obtained from the voltage value when positively changed and the current value, and the open-circuit voltage of the battery was calculated on the charge / discharge IV characteristic line.
[0006]
Further, the battery voltage value / current value detecting means includes a second remaining capacity detecting means for obtaining the remaining capacity of the battery based on the integrated value of the current values detected by the battery voltage value / current value detecting means, a comparing means, and a switching means. When the battery is initially used, the remaining capacity obtained by the second remaining capacity detecting means is used as an output, and the remaining capacity obtained by the first remaining capacity detecting means and the second remaining capacity detecting means are compared. When the difference between the remaining capacities exceeds a predetermined value, the remaining capacity can be switched to the remaining capacity obtained by the first remaining capacity detecting means and output.
[0007]
The remaining capacity can be output to the display device, and the input / output possible current of the battery calculated based on the charge / discharge IV characteristic line can be output to the display device together with the remaining capacity.
[0008]
[Action]
Since the charge / discharge IV characteristics are calculated from the voltage value and current value when the battery current changes from negative (charge) to positive (discharge) or from positive (discharge) to negative (charge), The touch of the open circuit voltage is small, and the remaining capacity of the battery can be obtained based on this accurate open circuit voltage.
Also, using the remaining capacity obtained from the integrated value of the current value as the output at the beginning of battery use, comparing the remaining capacity obtained based on the open-circuit voltage, and if the difference becomes larger than a predetermined value, the open-circuit voltage is set. By using the remaining capacity determined on the basis, it is possible to obtain an accurate remaining capacity throughout the elapsed time of use.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The embodiment of the present invention will be described with reference to examples.
FIG. 1 is a block diagram showing an embodiment in which the present invention is applied to detection of remaining capacity of a battery for driving a motor of a hybrid electric vehicle.
The hybrid electric vehicle includes an engine (ENG) 1 and a motor (MTR) 10 as drive sources. The engine 1 is not only a vehicle drive source but also a generator (GEN) 2 drive source. That is, the output shaft of the engine 1 is directly or indirectly connected to the generator 2, and generated power is output from the generator 2 when the engine 1 rotates. Therefore, the engine 1 and the generator 2 constitute an engine drive generator.
The output of the generator 2 is converted into DC power by the rectifier 3 and supplied to a chargeable / dischargeable lithium ion battery (hereinafter simply referred to as a battery) 5.
[0010]
The vehicle controller 11 inputs a signal indicating the battery state from the battery controller 8 together with a vehicle signal indicating the driver's accelerator operation, brake operation, and the like, and controls the operation of the inverter (INV) 9. A display device 12 is also connected to the battery controller 8.
[0011]
The battery controller 8 inputs the charging / discharging current and the inter-terminal voltage of the battery 5 detected by the current detector 6 and the voltage detector 7, respectively, calculates a signal representing the battery state from these values, Is satisfied, the power generation of the engine-driven generator is started via the power generation controller 4.
[0012]
The battery controller 8 detects the current value and the terminal voltage value flowing in the battery 5 by the current detector 6 and the voltage detector 7 at each predetermined sampling time, respectively, and the detected current flowing in the battery is changed from negative (charging) to positive. When changing to (discharge) or changing from positive (discharge) to negative (charge), a charge / discharge IV characteristic line is obtained.
Further, the maximum dischargeable current and the maximum acceptable current are calculated based on the charge / discharge IV characteristic line. And
When the maximum dischargeable current ≦ the maximum acceptable current, power generation by the engine-driven generator is started.
[0013]
FIG. 2 is a diagram showing charge / discharge IV characteristics (lines). The upper broken line parallel to the current indicates the full charge voltage of the battery, that is, the maximum voltage Vmax, and the lower broken line indicates the discharge lower limit voltage of the battery, that is, the minimum voltage Vmin.
In the figure, the point where the diagonal line reaches the line indicating the maximum voltage Vmax is the maximum acceptable current Ic, and the point on the current axis corresponding to the point where the line reaches the line indicating the minimum voltage Vmin is the maximum dischargeable current Id. .
The input / output power can be obtained from the maximum dischargeable current and the maximum acceptable current, that is, the input / output possible current.
[0014]
The power generation controller 4 monitors the number of revolutions of the engine 1, the output voltage and current of the generator 2 and controls the output voltage of the generator 2 to be constant when the engine-driven generator is operating. .
[0015]
FIG. 3 is a flowchart showing the control operation of the battery remaining capacity calculation display in the battery controller 8.
In step 101, when the hybrid electric vehicle is operated, that is, when the use of the battery 5 is started, the open voltage of the battery 5 is detected by the voltage detector 7, the remaining capacity of the battery 5 is calculated based on the open voltage, and the initial value is obtained. To do. Here, the remaining capacity is obtained from the relationship between the predetermined remaining capacity and the open circuit voltage. FIG. 4 shows an example of the relationship between the remaining capacity and the open circuit voltage in the case of a lithium ion battery. From this figure, if the open circuit voltage of the battery is obtained, the remaining capacity can be obtained.
[0016]
During operation of the hybrid electric vehicle, in step 102, the current (charge current) flowing through the battery 5 and the battery voltage (terminal voltage) are detected by the current detector 6 and the voltage detector 7 every predetermined sampling time.
In step 103, the remaining capacity is calculated by integrating the sampling current values detected in step 102.
The remaining capacity can be calculated by dividing the integrated current value by the rated capacity of the battery 5.
In the next step 104, the remaining capacity obtained from the integrated current value is displayed on the display device 12.
[0017]
In step 105, the sampling current value and voltage value when the current value detected by the current detector 6 changes from negative (charge) to positive (discharge) or from positive (discharge) to negative (charge) are obtained. Based on this, the battery controller 8 obtains charge / discharge IV characteristics.
[0018]
The charge / discharge IV characteristic of the battery is represented as a characteristic line in which the voltage decreases linearly as the current value increases as shown in FIG.
The charge / discharge IV characteristic line can also be obtained from two sampling values at which the current value changes between positive and negative. However, a predetermined voltage value at which discharge starts or a voltage value near the voltage value at which charging starts is determined. Sampling is performed at predetermined time intervals when detected, and the detected charge / discharge current I and terminal voltage V are plotted on a graph with the vertical axis representing the voltage axis and the horizontal axis representing the current axis. It can also be obtained by linear approximation by the least square method.
[0019]
In step 106, an open circuit voltage is calculated from the charge / discharge IV characteristic line. The open circuit voltage is obtained as a voltage value at the intersection of the oblique line approximated by a straight line and the voltage axis (Y axis).
In step 107, the remaining capacity is obtained from the open circuit voltage obtained in step 106 using the relationship map between the remaining capacity and the open circuit voltage in FIG.
[0020]
In step 108, the remaining capacity calculated from the integrated current value in step 103 is compared with the remaining capacity obtained from the open circuit voltage in step 107. If the difference between the two remaining capacities is equal to or greater than the predetermined value, the process proceeds to step 109. Otherwise, the process returns to step 104, and the remaining capacity obtained from the integrated current value is output to the display device 12 for display.
Generally, immediately after the start of charging / discharging, the remaining capacity obtained from the integrated current value is obtained with higher accuracy.
[0021]
On the other hand, in step 109, the remaining capacity obtained from the integrated current value in step 103 is replaced with the remaining capacity obtained from the open voltage in step 107 as the value of the remaining capacity.
In step 110, the remaining capacity obtained from the open circuit voltage as the change result is displayed on the display device 12. In addition to the display of the remaining capacity, the input / output possible current calculated based on the charge / discharge IV characteristics can also be displayed.
[0022]
Here, the above steps 101 and 102 constitute the battery voltage value / current value detecting means of the invention, steps 105 and 106 are the open circuit voltage calculating means, step 107 is the first remaining capacity detecting means, and step 103 is the The second remaining capacity detection means, step 108 constitutes comparison means, and step 109 constitutes switching means.
[0023]
In this embodiment, the current value changes from negative (charge) to positive (discharge), or sampling is detected in a region where the current value changes from positive (discharge) to negative (charge). There are always negative (charging) points and positive (discharging) points. Compared to the case where the open-circuit voltage is calculated from the current value obtained only in the positive (discharging) area, for example. Thus, the error is small and the open circuit voltage can be calculated with high accuracy.
[0024]
FIG. 5 shows the residual capacity obtained by the present embodiment and the residual capacity obtained by the conventional method in relation to the elapsed time of use. A is the residual capacity error according to the present embodiment, and B is the conventional current integration. An error when the remaining capacity is obtained in step (1), and C is an error when the remaining capacity is obtained by calculating the open circuit voltage at a predetermined time interval.
The remaining capacity (B) obtained based on the integrated current value has good accuracy at the beginning of use, but the error increases with time. On the other hand, the remaining capacity (C) obtained from the conventional open circuit voltage can suppress the error range to a certain extent, but the accuracy at the beginning of use is inferior to that in the case of (B).
In (A) according to the embodiment, the open circuit voltage calculated in a region where the current value spans positive and negative after the lapse of a predetermined time while obtaining the same high accuracy as (B) based on the current integrated value at the beginning of use. Since the remaining capacity based on is displayed, the error range is suppressed to be smaller than in (C).
[0025]
In the above description, since the relationship between the remaining capacity of the lithium ion battery and the open circuit voltage is hardly affected by the temperature and the degree of deterioration, the remaining capacity is calculated by dividing the current integrated value by the rated capacity of the battery 5. However, when the battery temperature is detected according to the type of the battery 5, the remaining capacity can be obtained more accurately by dividing the current integrated value by the battery capacity at that temperature.
[0026]
As described above, according to the present embodiment, since the charge / discharge IV characteristic line is accurately obtained, the open-circuit voltage is changed depending on the situation thereafter while adopting the remaining capacity obtained from the current integrated value at the beginning of battery use. The remaining capacity with high accuracy can be displayed.
[0027]
In the case of a hybrid electric vehicle, since the battery 5 is rarely fully charged or completely discharged, the integrated current value cannot be reset in a fully charged or empty state, while charging and discharging are repeated frequently. Therefore, although it is required to obtain the remaining capacity from the open circuit voltage, according to the present embodiment, the remaining capacity calculation based on the integrated current value and the remaining capacity calculation based on the open circuit voltage are combined to provide a highly accurate remaining capacity. This is particularly effective for hybrid electric vehicles.
[0028]
【The invention's effect】
As described above, according to the present invention, in the remaining capacity detection device that determines the remaining capacity of the battery based on the open circuit voltage calculated from the voltage value and current value of the battery, the current value is changed from positive to negative when calculating the open circuit voltage. The charge / discharge IV characteristic line is obtained from the voltage value and the current value when changing from negative to positive, and the open circuit voltage of the battery is calculated on the charge / discharge IV characteristic line. The touch of the open circuit voltage is small, and based on this, the remaining capacity of the battery with high accuracy can be obtained.
[0029]
In addition, using the remaining capacity obtained from the integrated value of the current value as the output at the beginning of battery use, comparing the remaining capacity obtained based on the open circuit voltage, and if the difference becomes larger than a predetermined value, the open circuit voltage is set. By using the remaining capacity determined on the basis, it is possible to obtain an accurate remaining capacity throughout the elapsed time of use.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a configuration of a battery remaining capacity detection apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating a charge / discharge IV characteristic line;
FIG. 3 is a flowchart showing a control operation of the embodiment.
FIG. 4 is a map showing the relationship between the remaining battery capacity and the open circuit voltage.
FIG. 5 is an explanatory diagram showing an error between the remaining capacity obtained by the example and the remaining capacity obtained by the comparative example in relation to the elapsed usage time.
FIG. 6 is an explanatory diagram showing a problem of open circuit voltage calculation in a conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Engine 2 Generator 3 Rectifier 4 Vehicle controller 5 Lithium ion battery 6 Current detector 7 Voltage detector 8 Battery controller 9 Inverter 10 Motor 11 Vehicle controller 12 Display device

Claims (4)

電池の電圧値と電池に流れる電流値とを検出する電池電圧値・電流値検出手段と、検出された電圧値と電流値から電池の開放電圧を算出する開放電圧算出手段と、開放電圧に基づいて電池の残存容量を求める第1の残存容量検出手段とを有する電池の残存容量検出装置において、
前記開放電圧算出手段が、前記電流値が正から負に変化しまたは負から正に変化したときの電圧値と当該電流値とから充放電I−V特性線を求め、該充放電I−V特性線上で電池の開放電圧を算出するものであることを特徴とする電池の残存容量検出装置。
A battery voltage value and current value detecting means for detecting a current flowing through the voltage value and the battery of the battery, and the open-circuit voltage calculation means for calculating the open circuit voltage of the battery from the detected voltage value and current value, based on the open-circuit voltage A battery remaining capacity detecting device having first remaining capacity detecting means for determining the remaining capacity of the battery;
The open- circuit voltage calculating means obtains a charge / discharge IV characteristic line from the voltage value and the current value when the current value changes from positive to negative or from negative to positive, and the charge / discharge IV A battery remaining capacity detecting device for calculating an open circuit voltage of a battery on a characteristic line.
さらに、前記電池電圧値・電流値検出手段で検出された電流値の積算値に基づいて電池の残存容量を求める第2の残存容量検出手段を備えて、電池の使用当初は当該第2の残存容量検出手段で求めた残存容量を出力とし
前記第1の残存容量検出手段と第2の残存容量検出手段でそれぞれ求めた残存容量を比較する比較手段と、
第1の残存容量検出手段で求めた残存容量と第2の残存容量検出手段で求めた残存容量の差が所定値以上になると、残存容量を前記第1の残存容量検出手段で求めた残存容量に切り替える切り替え手段とを有することを特徴とする請求項1記載の電池の残存容量検出装置。
The battery further comprises second remaining capacity detecting means for determining the remaining capacity of the battery based on the integrated value of the current values detected by the battery voltage value / current value detecting means. Use the remaining capacity obtained by the capacity detection means as the output ,
A comparison means for comparing the remaining capacities respectively obtained by the first remaining capacity detecting means and the second remaining capacity detecting means;
If the difference between the remaining capacity determined by the charge and the second state of charge detecting means obtained in the first remaining capacity detecting means is equal to or greater than a predetermined value, the remaining capacity of obtaining the remaining capacity by the first remaining capacity detecting means The battery remaining capacity detection device according to claim 1, further comprising switching means for switching between the two.
前記残存容量を表示装置に出力することを特徴とする請求項1または2記載の電池の残存容量検出装置。3. The battery remaining capacity detection device according to claim 1, wherein the remaining capacity is output to a display device. 前記充放電I−V特性線を基に算出した電池の入出力可能電流を前記残存容量とともに前記表示装置に出力することを特徴とする請求項3記載の電池の残存容量検出装置。4. The battery remaining capacity detecting device according to claim 3, wherein a battery input / output possible current calculated based on the charge / discharge IV characteristic line is output to the display device together with the remaining capacity.
JP01488698A 1998-01-09 1998-01-09 Battery remaining capacity detection device Expired - Fee Related JP3767150B2 (en)

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