JP4946269B2 - Battery characteristic calculation device and battery capacity calculation device - Google Patents

Battery characteristic calculation device and battery capacity calculation device Download PDF

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JP4946269B2
JP4946269B2 JP2006230518A JP2006230518A JP4946269B2 JP 4946269 B2 JP4946269 B2 JP 4946269B2 JP 2006230518 A JP2006230518 A JP 2006230518A JP 2006230518 A JP2006230518 A JP 2006230518A JP 4946269 B2 JP4946269 B2 JP 4946269B2
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吉正 土岐
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Nissan Motor Co Ltd
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Description

本発明は、電池のパワー対容量特性を算出する電池特性演算装置、および、そのパワー対容量特性に基づいて電池の容量を算出する電池容量演算装置に関する。   The present invention relates to a battery characteristic calculation device that calculates power-capacity characteristics of a battery, and a battery capacity calculation device that calculates battery capacity based on the power-capacity characteristics.

従来、電気車両における組電池の容量を推定する場合には、放電により得られる電池の劣化度に応じた補正係数を用いて、初期電池の出力特性および容量特性に対して補正するようにしている。また、電池はその温度により出力特性が変化するため、温度に応じた温度補正係数を用いて出力特性の補正を行うようにもしている(例えば、特許文献1参照)。   Conventionally, when estimating the capacity of an assembled battery in an electric vehicle, correction is made to the output characteristics and capacity characteristics of the initial battery using a correction coefficient corresponding to the degree of deterioration of the battery obtained by discharging. . Further, since the output characteristics of the battery change depending on the temperature, the output characteristics are corrected using a temperature correction coefficient corresponding to the temperature (see, for example, Patent Document 1).

特開平10−289734号公報JP-A-10-289734

しかしながら、電池劣化にともない温度特性が変化することがあり、そのような場合、電池温度による温度補正を行うことでかえって電池特性の算出精度を低下させてしまうという問題があった。電池特性算出精度の低下は容量の算出精度の低下を招き、容量表示計の動きが不自然なものとなり、電池の実力値よりも過小に容量が表示されたり、逆に、過大な容量が表示計に表示されてしまうおそれがあった。   However, the temperature characteristic may change as the battery deteriorates. In such a case, there is a problem that the calculation accuracy of the battery characteristic is lowered by performing temperature correction based on the battery temperature. A decrease in battery characteristic calculation accuracy will lead to a decrease in capacity calculation accuracy, the movement of the capacity indicator will be unnatural, and the capacity will be displayed below the actual capacity of the battery, or conversely, an excessive capacity will be displayed. There was a risk of being displayed on the total.

請求項1の発明は、パワー対容量特性の初期特性を電池温度に基づく温度補正係数で補正して、温度補正されたパワー対容量特性を算出する電池特性演算装置に適用され、電池の劣化度が所定の基準値を超えているか否かを判定する判定手段と、劣化度増大時と劣化度減少時とで前記基準値を異ならせ、劣化度減少時の基準値を劣化度増大時の基準値より小さく設定する設定手段と、前記判定手段により前記基準値を超えていると判定されると、電池の劣化度に応じて前記温度補正係数を補正する補正手段と、を備え、補正手段で補正された温度補正係数に基づいて初期特性を補正することを特徴とする。
請求項の発明による電池容量演算装置は、請求項1または2に記載の電池特性演算装置により算出されたパワー対容量特性に基づいて、電池の容量を算出することを特徴とする。
The invention according to claim 1, the initial characteristics of the power versus capacity characteristic is corrected by the temperature correction coefficient based on the battery temperature, is applied to the battery characteristic calculation unit for calculating a temperature corrected power versus capacity characteristic, the deterioration degree of the battery The determination means for determining whether or not the value exceeds a predetermined reference value, and the reference value is different between when the degree of deterioration is increased and when the degree of deterioration is decreased, and the reference value when the degree of deterioration is decreased is a reference when the degree of deterioration is increased comprising setting means for setting smaller than the value, it is determined to exceed the reference value by the determination unit, and a correcting means for correcting the temperature correction coefficient according to the deterioration degree of the battery, the correction means The initial characteristic is corrected based on the corrected temperature correction coefficient.
According to a third aspect of the present invention, there is provided a battery capacity calculation device that calculates the capacity of a battery based on the power versus capacity characteristic calculated by the battery characteristic calculation device according to the first or second aspect.

本発明によれば、電池の劣化度に応じて補正された温度補正係数に基づいてパワー対容量特性が算出されるので、パワー対容量特性の精度向上を図ることができる。   According to the present invention, since the power-to-capacity characteristic is calculated based on the temperature correction coefficient corrected according to the degree of deterioration of the battery, the accuracy of the power-to-capacitance characteristic can be improved.

以下、図を参照して本発明を実施するための最良の形態について説明する。図1は、本発明による電池容量演算装置の一実施の形態を説明するブロック図である。図1は電気車両に搭載される電池容量演算装置を例に示したものであり、車両駆動用の電池1にはリチウムイオン二次電池を用いた組電池が使用されている。   Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a block diagram illustrating an embodiment of a battery capacity calculation device according to the present invention. FIG. 1 shows an example of a battery capacity calculation device mounted on an electric vehicle, and an assembled battery using a lithium ion secondary battery is used as a vehicle driving battery 1.

電池1の温度Tは温度センサ2により検出され、充放電時の電圧Vおよび電流Iは電圧検出部3および電流検出部4により検出される。これらの温度T,電圧Vおよび電流Iは残存容量の演算等を行う演算装置5に入力される。演算装置5には、演算部51および記憶部52が設けられている。演算装置5で演算された残存容量は容量計6へと出力され、容量計6により残存容量が表示される。記憶部52には、後述するパワー対容量特性の初期特性や温度補正係数αなどが記憶されている。なお、本発明におけるパワーとは電池が入力可能な電力を意味し、以下では単にパワーと記載する。   The temperature T of the battery 1 is detected by the temperature sensor 2, and the voltage V and current I at the time of charging / discharging are detected by the voltage detector 3 and the current detector 4. These temperature T, voltage V, and current I are input to an arithmetic unit 5 that calculates the remaining capacity. The computing device 5 is provided with a computing unit 51 and a storage unit 52. The remaining capacity calculated by the calculation device 5 is output to the capacity meter 6, and the capacity meter 6 displays the remaining capacity. The storage unit 52 stores an initial characteristic of a power-capacitance characteristic described later, a temperature correction coefficient α, and the like. In addition, the power in this invention means the electric power which a battery can input, and is only described as power below.

本実施の形態の電池容量演算装置では、電池仕様に基づくパワー対容量特性の初期特性を電池1の状態に応じて補正し、その補正されたパワー対容量特性を用いて残存容量を算出するようにしている。まず、パワー対容量特性の補正方法について説明する。図2(a)の特性曲線L1は電池1の初期特性(初期電池のパワー対容量特性)を示しており、Whiniは初期容量である。縦軸の出力(パワー)の単位はkW、横軸の容量の単位はA・hまたはkW・hである。なお、入力の場合も出力の場合も同様に考えることができ、以下では出力の場合を例に説明する。   In the battery capacity calculation device according to the present embodiment, the initial characteristic of the power-capacity characteristic based on the battery specifications is corrected according to the state of the battery 1, and the remaining capacity is calculated using the corrected power-capacity characteristic. I have to. First, a method for correcting power-capacitance characteristics will be described. A characteristic curve L1 in FIG. 2A shows the initial characteristic of the battery 1 (power versus capacity characteristic of the initial battery), and Whini is the initial capacity. The unit of output (power) on the vertical axis is kW, and the unit of capacity on the horizontal axis is A · h or kW · h. Note that the case of input and the case of output can be considered in the same manner, and the case of output will be described below as an example.

通常、パワー対容量特性Wh(P)はパワーPのn次式で表すことができ、特に、リチウムイオン二次電池の場合には、次式(1)のように近似することができる。ここで、係数a,b,c,dは初期電池の特性から決定される。
Wh1(P)=a×P3+b×P2+c×P+d …(1)
In general, the power-to-capacitance characteristic Wh (P) can be expressed by an nth-order expression of power P. In particular, in the case of a lithium ion secondary battery, it can be approximated as the following expression (1). Here, the coefficients a, b, c, and d are determined from the characteristics of the initial battery.
Wh1 (P) = a × P 3 + b × P 2 + c × P + d (1)

電池1が劣化していない電池初期時には、温度補正係数αを用いて初期特性曲線L1の出力特性を図2(a)の特性曲線L2に示すように補正する。電池1の初期特性をWh1(P)、特性曲線L2の特性式をWh2(P)と表すと、Wh2(P)は次式(2)のように表される。
Wh2(P)=Wh1(P/α)
=a(P/α)3+b(P/α)2+c(P/α)+d …(2)
At the initial stage of the battery when the battery 1 is not deteriorated, the output characteristic of the initial characteristic curve L1 is corrected as shown by the characteristic curve L2 in FIG. When the initial characteristic of the battery 1 is expressed as Wh1 (P) and the characteristic expression of the characteristic curve L2 is expressed as Wh2 (P), Wh2 (P) is expressed as the following expression (2).
Wh2 (P) = Wh1 (P / α)
= A (P / α) 3 + b (P / α) 2 + c (P / α) + d (2)

また、電池1が劣化している場合には、特性曲線L1を劣化による出力劣化係数βおよび容量劣化係数γで補正した後に、さらに、温度補正係数αで温度補正するようにしている。図2(b)において特性曲線L3は、初期特性曲線L1を出力劣化係数βおよび容量劣化係数γで補正したものである。特性曲線L3の特性式Wh3(P)は、次式(3)のように表せる。
Wh3(P)=Wh1(P/β)×γ …(3)
When the battery 1 is deteriorated, the characteristic curve L1 is corrected with the output deterioration coefficient β and the capacity deterioration coefficient γ due to deterioration, and then the temperature is corrected with the temperature correction coefficient α. In FIG. 2B, a characteristic curve L3 is obtained by correcting the initial characteristic curve L1 with the output deterioration coefficient β and the capacity deterioration coefficient γ. The characteristic equation Wh3 (P) of the characteristic curve L3 can be expressed as the following equation (3).
Wh3 (P) = Wh1 (P / β) × γ (3)

さらに、この特性曲線L3を温度補正係数αで補正したものが特性曲線L4である。そして、この特性曲線L4に基づいて残存容量を算出する。特性曲線L4の特性式Wh4(P)は、次式(4)で表される。
Wh4(P)=Wh1(P/αβ)×γ …(4)
Further, the characteristic curve L4 is obtained by correcting the characteristic curve L3 with the temperature correction coefficient α. Then, the remaining capacity is calculated based on this characteristic curve L4. The characteristic equation Wh4 (P) of the characteristic curve L4 is expressed by the following equation (4).
Wh4 (P) = Wh1 (P / αβ) × γ (4)

ただし、初期電池(劣化していない電池)を用いても、実車にて使用可能な容量は図2(a)に示した初期容量Whini(=Wh1(0))とはならず、図3に示すようなPminとの交点におけるWh1(Pmin)となる。劣化後においてはWh2(Pmin)となる。ここで、Pminは車両として最低限必要な最低保証出力であり、電池の劣化度および電池温度によらず常に一定の値となる。   However, even if an initial battery (a battery that has not deteriorated) is used, the capacity that can be used in the actual vehicle is not the initial capacity Whini (= Wh1 (0)) shown in FIG. Wh1 (Pmin) at the intersection with Pmin as shown. After deterioration, it becomes Wh2 (Pmin). Here, Pmin is the minimum required output required for the vehicle, and is always a constant value regardless of the degree of deterioration of the battery and the battery temperature.

ところで、温度補正係数αは、電池劣化により変化する場合がある。そこで、本実施の形態では、電池劣化による温度補正係数αの変化も考慮してパワー対容量特性Whを補正するようにした。本実施の形態では、電池劣化の程度に応じて、初期値α0(初期電池の温度補正係数)および劣化時の値α’のいずれかを選択して用いる場合を例に説明する。なお、温度補正係数αの初期値α0および劣化時の値α’は、それぞれ記憶部52にテーブルとして予め記憶されている。   Incidentally, the temperature correction coefficient α may change due to battery deterioration. Therefore, in the present embodiment, the power-capacitance characteristic Wh is corrected in consideration of a change in the temperature correction coefficient α due to battery deterioration. In the present embodiment, an example will be described in which one of the initial value α0 (initial battery temperature correction coefficient) and the deterioration value α ′ is selected and used in accordance with the degree of battery deterioration. Note that the initial value α0 and the deterioration value α ′ of the temperature correction coefficient α are stored in advance in the storage unit 52 as tables.

図6は、劣化補正係数βの変化に対する初期値α0および劣化時の値α’の変化を示す図である。記憶部52には、これらの曲線に対応する温度補正テーブルが記憶されている。α0およびα’は、基準温度T1の時の値を1として表され、温度が高くなるほど大きくなるように設定されている。すなわち、電池温度が基準温度T1よりも高いときには出力が大きくなるように補正され、電池温度が基準温度T1よりも低いときには出力が小さくなるように補正される。そして、劣化時には、その補正の程度が初期時に比べて大きくなる。   FIG. 6 is a diagram showing changes in the initial value α0 and the deterioration value α ′ with respect to the change in the deterioration correction coefficient β. The storage unit 52 stores temperature correction tables corresponding to these curves. α0 and α ′ are represented by 1 as the value at the reference temperature T1, and are set to increase as the temperature increases. That is, the output is corrected so as to increase when the battery temperature is higher than the reference temperature T1, and is corrected so as to decrease when the battery temperature is lower than the reference temperature T1. At the time of deterioration, the degree of correction becomes larger than that at the initial time.

[残存容量算出の説明]
図4は、演算部51で処理される残存容量算出の手順を示すフローチャートである。なお、図4に示すフローチャートは放電時にも充電時にも適用できるものであり、起動中は繰り返し実行される。ステップS1では放電中または充電中の電流および電圧の変化をサンプリングし、サンプリングデータとして記憶部52にストックする。そして、そのストックされたサンプリングデータを用いて、それが放電中のデータであれば出力可能パワーPmax(out)を、また、充電中のデータであれば入力可能パワーPmax(in)を算出する。
[Explanation of remaining capacity calculation]
FIG. 4 is a flowchart showing a procedure of remaining capacity calculation processed by the calculation unit 51. Note that the flowchart shown in FIG. 4 can be applied both during discharging and during charging, and is repeatedly executed during startup. In step S1, changes in current and voltage during discharging or charging are sampled and stored in the storage unit 52 as sampling data. Then, using the stocked sampling data, if the data is discharging, the output possible power Pmax (out) is calculated, and if the data is charging, the input possible power Pmax (in) is calculated.

ここで、出力可能パワーPmax(out)の演算は次のように行われる。規定の放電電流毎に図5(a)のようにIV特性を一次回帰演算して、そのIV特性(回帰直線)と放電下限電圧(車両システムとしての使用下限電圧)Vminとの交点から、出力可能パワーPmax(out)を次式(5)のように算出する。一方、入力可能パワーPmax(in)の場合も同様で、図5(b)に示すようなIV特性を一次回帰演算し、充電上限電圧Vmaxとの交点から次式(6)のように入力可能パワーPmax(in)を算出する。
Pmax(out)=Vmin×Imax(out) …(5)
Pmax(in)=Vmax×Imax(in) …(6)
Here, the calculation of the output possible power Pmax (out) is performed as follows. As shown in Fig. 5 (a), the IV characteristic is linearly regressed for each specified discharge current and output from the intersection of the IV characteristic (regression line) and the discharge lower limit voltage (use lower limit voltage as a vehicle system) Vmin. The possible power Pmax (out) is calculated as in the following equation (5). On the other hand, the same applies to the power Pmax (in) that can be input, and the IV characteristic as shown in FIG. 5B can be linearly regressed and input from the intersection with the charging upper limit voltage Vmax as shown in the following equation (6). The power Pmax (in) is calculated.
Pmax (out) = Vmin × Imax (out) (5)
Pmax (in) = Vmax × Imax (in) (6)

ステップS2では、出力劣化係数β(out)または入力劣化係数β(in)を算出する。出力劣化係数β(out)の算出手順について説明すると、まず、ある特定SOC(充電率:Stateof Charge)区間にて算出される内部抵抗R(out)を求める。特定SOCとは、例えば、満充電区間と定められた区間などであり、その区間において上述した一次回帰演算を行ってIV特性を求め、その回帰直線の傾きから内部抵抗R(out)を算出する。   In step S2, the output deterioration coefficient β (out) or the input deterioration coefficient β (in) is calculated. The procedure for calculating the output deterioration coefficient β (out) will be described. First, an internal resistance R (out) calculated in a specific SOC (State of Charge) section is obtained. The specific SOC is, for example, a section defined as a full charge section. In the section, the above-described primary regression calculation is performed to obtain an IV characteristic, and the internal resistance R (out) is calculated from the slope of the regression line. .

内部抵抗R(out)は電池温度Tに依存するので、式(7)のように温度補正係数α(out)を用いて基準温度での内部抵抗R’(out)を算出する。なお、α(out)は出力時の温度補正係数であって、後述するα(in)は入力時の温度補正係数である。式(7)の温度補正係数α(out)には、初期値α0(out)が用いられる。算出された内部抵抗R’(out)と初期電池の基準温度での内部抵抗である初期値Rini(out)とから、式(8)のように出力劣化係数β(out)を算出する。
R’(out)=R(out)÷α(out) …(7)
β(out)=Rini(out)/R’(out) …(8)
Since the internal resistance R (out) depends on the battery temperature T, the internal resistance R ′ (out) at the reference temperature is calculated using the temperature correction coefficient α (out) as shown in Equation (7). Α (out) is a temperature correction coefficient at the time of output, and α (in) described later is a temperature correction coefficient at the time of input. The initial value α0 (out) is used as the temperature correction coefficient α (out) in equation (7). From the calculated internal resistance R ′ (out) and the initial value Rini (out) which is the internal resistance at the reference temperature of the initial battery, the output deterioration coefficient β (out) is calculated as shown in Equation (8).
R ′ (out) = R (out) ÷ α (out) (7)
β (out) = Rini (out) / R '(out) (8)

なお、入力劣化係数β(in)についても同様であって、ある特定SOC区間の充電中のデータを用いて一次回帰演算を行い、図5(b)に示す回帰直線の傾きから充電時における内部抵抗R(in)を算出する。放電時の場合と同様に、この内部抵抗R(in)を温度補正係数α(in)で補正して基準温度での内部抵抗R’(in)を算出し(式(9)参照)、式(10)により出力劣化係数β(in)を算出する。
R’(in)=R(in)÷α(in) …(9)
β(in)=Rini(in)/R’(in) …(10)
The same applies to the input deterioration coefficient β (in), and a linear regression calculation is performed using data during charging in a specific SOC section, and the internal line at the time of charging is determined from the slope of the regression line shown in FIG. Calculate the resistance R (in). As in the case of discharging, the internal resistance R (in) is corrected by the temperature correction coefficient α (in) to calculate the internal resistance R ′ (in) at the reference temperature (see equation (9)). The output deterioration coefficient β (in) is calculated from (10).
R ′ (in) = R (in) ÷ α (in) (9)
β (in) = Rini (in) / R '(in) (10)

図4に戻って、ステップS3では容量劣化係数γ(out)またはγ(in)を算出する。容量劣化係数γ(out),γ(in)については、一般的にγ(out)=β(out),γ(in)=β(in)を基本とするが、実際には電池特性を考慮して次式(11),(12)により算出する。ここで、η(out),η(in)は電池固有の出力劣化係数β(out),β(in)に対する容量劣化特性係数であり、記憶部52に予め記憶されている。
γ(out)=β(out)×η(out) …(11)
γ(in)=β(in)×η(in) …(12)
Returning to FIG. 4, in step S3, the capacity deterioration coefficient γ (out) or γ (in) is calculated. The capacity degradation coefficients γ (out) and γ (in) are generally based on γ (out) = β (out) and γ (in) = β (in), but in reality, the battery characteristics are taken into account. Then, the following equations (11) and (12) are used for calculation. Here, η (out) and η (in) are capacity deterioration characteristic coefficients with respect to the battery-specific output deterioration coefficients β (out) and β (in), and are stored in the storage unit 52 in advance.
γ (out) = β (out) × η (out) (11)
γ (in) = β (in) × η (in) (12)

続くステップS4からステップS8までは温度補正係数α(out),α(in)を求めるための処理であり、図7を参照しながら説明する。前述したように、電池劣化の程度に応じて、温度補正係数αとして初期値α0(out),α0(in)または劣化時の値α’(out),α’(in)のいずれかを用いるようにしている。電池劣化の程度は、出力劣化係数β(out)または入力劣化係数β(in)により表される。   The subsequent steps S4 to S8 are processes for obtaining the temperature correction coefficients α (out) and α (in), and will be described with reference to FIG. As described above, the initial value α0 (out), α0 (in) or the value α ′ (out), α ′ (in) at the time of deterioration is used as the temperature correction coefficient α depending on the degree of battery deterioration. Like that. The degree of battery deterioration is represented by an output deterioration coefficient β (out) or an input deterioration coefficient β (in).

図7は、出力劣化係数β(out)と温度補正係数α(out),α’(out)との関係を示す図である。入力劣化係数β(in)についても同様であり、図中のα(out),α’(out),β1(out),β2(out)の各々をα(in),α’(in),β1(in),β2(in)で置き換えれば良い。なお、温度補正係数α(out),α(in)のいずれの場合も同様の処理が行われるので、ステップS4〜S8では、これらの記号の代わりに記号α,βを共通の記号として示した。なお、各処理の説明では、出力に関する温度補正係数α(out)を例に説明する。   FIG. 7 is a diagram showing the relationship between the output deterioration coefficient β (out) and the temperature correction coefficients α (out) and α ′ (out). The same applies to the input deterioration coefficient β (in), and α (out), α ′ (out), β1 (out), and β2 (out) in the figure are represented by α (in), α ′ (in), Replace with β1 (in) and β2 (in). Since the same processing is performed in both cases of the temperature correction coefficients α (out) and α (in), symbols α and β are shown as common symbols instead of these symbols in steps S4 to S8. . In the description of each process, the temperature correction coefficient α (out) related to output will be described as an example.

まず、ステップS4では、ステップS2で算出された出力劣化係数β(out)が前回算出された出力劣化係数β’(out)以上であるか否かを判定する。すなわち、出力劣化係数β(out)の変化が、図7の下側のA→B,B→Cのような変化なのか、上側のC→B,B→Aのような変化なのかを判定する。ステップS4において、β(out)≧β’(out)と判定されるとステップS5へと進み、β(out)<β’(out)と判定されるとステップS7へ進む。   First, in step S4, it is determined whether or not the output deterioration coefficient β (out) calculated in step S2 is greater than or equal to the previously calculated output deterioration coefficient β ′ (out). That is, it is determined whether the change in the output deterioration coefficient β (out) is a change such as A → B and B → C on the lower side of FIG. 7 or a change such as C → B and B → A on the upper side. To do. If it is determined in step S4 that β (out) ≧ β ′ (out), the process proceeds to step S5, and if it is determined that β (out) <β ′ (out), the process proceeds to step S7.

図7のA→B,B→Cのように出力劣化係数β(out)が増加している場合には、ステップS4からステップS5へと進み、出力劣化係数β(out)が基準値β2(out)を超えているか否かを判定する。基準値β2(out)は予め設定されており、例えば、劣化度が10%の場合の出力劣化係数の値を用いる。ステップS5でβ(out)>β2(out)と判定されるとステップS6へ進み、劣化時のα’(out)のテーブルを用いて算出される値を温度補正係数αとして採用する。一方、β(out)≦β2(out)と判定されるとステップS8へ進み、初期値α0(out)のテーブルを用いて算出される値を温度補正係数αとして採用する。   When the output deterioration coefficient β (out) increases as in A → B and B → C in FIG. 7, the process proceeds from step S4 to step S5, where the output deterioration coefficient β (out) is the reference value β2 ( out) is determined. The reference value β2 (out) is set in advance, and for example, the value of the output deterioration coefficient when the deterioration degree is 10% is used. If it is determined in step S5 that β (out)> β2 (out), the process proceeds to step S6, and a value calculated using a table of α ′ (out) at the time of deterioration is adopted as the temperature correction coefficient α. On the other hand, if it is determined that β (out) ≦ β2 (out), the process proceeds to step S8, and a value calculated using a table of initial values α0 (out) is adopted as the temperature correction coefficient α.

一方、出力劣化係数β’(out)が図7の上側のC→B,B→Aのように変化してステップS7に進んだ場合には、ステップS7において出力劣化係数β(out)が基準値β1(out)を下回っているか否かを判定する。この基準値β1(out)は基準値β2(out)よりも小さく設定されている。ステップS7でβ(out)<β1(out)と判定されるとステップS8へ進み、初期値α0(out)のテーブルを用いて算出される値を温度補正係数αとして採用する。一方、β(out)≧β1(out)と判定されるとステップS6へ進み、劣化時補正係数α’(out)のテーブルを用いて算出される値を温度補正係数αとして採用する。   On the other hand, when the output deterioration coefficient β ′ (out) changes as C → B and B → A on the upper side of FIG. 7 and proceeds to step S7, the output deterioration coefficient β (out) is the reference in step S7. It is determined whether it is below the value β1 (out). This reference value β1 (out) is set smaller than the reference value β2 (out). If it is determined in step S7 that β (out) <β1 (out), the process proceeds to step S8, and a value calculated using the table of initial values α0 (out) is adopted as the temperature correction coefficient α. On the other hand, if it is determined that β (out) ≧ β1 (out), the process proceeds to step S6, and a value calculated using the table of the correction coefficient α ′ (out) at the time of deterioration is adopted as the temperature correction coefficient α.

すなわち、出力劣化係数βが図7の下側のA→B→Cのように変化する場合には、テーブル変更の基準値をβ2(out)とし、上側のC→B→Aのように変化する場合には、変更の基準値をβ1(out)とする。   That is, when the output deterioration coefficient β changes as A → B → C on the lower side of FIG. 7, the reference value for changing the table is β2 (out), and changes as C → B → A on the upper side. In this case, the reference value for change is β1 (out).

一般に、電池劣化が徐々に進行していても、算出誤差によって出力劣化係数βがばらつくために劣化が見かけ上回復することがある。そのため、温度補正係数αの変更基準点付近において、温度補正係数αが頻繁に変更されるというハンチング現象が生じる。しかしながら、温度補正係数αの変更に際して、上述したようなヒステリシスを設けたことにより、そのようなハンチング現象を防止することができる。   In general, even when the battery deterioration is gradually progressing, the output deterioration coefficient β varies due to the calculation error, so that the deterioration may be apparently recovered. Therefore, a hunting phenomenon occurs in which the temperature correction coefficient α is frequently changed in the vicinity of the change reference point of the temperature correction coefficient α. However, such a hunting phenomenon can be prevented by providing the hysteresis as described above when changing the temperature correction coefficient α.

例えば、出力劣化係数βが図7のBの状態からCの状態に変化した後、演算誤差によってBの状態が出現した場合でも温度補正係数αはα’に維持されたままで、安定した温度補正係数αを得ることができる。なお、ここでは劣化時の温度補正係数を一種類のα’としたが、大きさの異なる複数の温度補正係数α’を設定しても良い。   For example, after the output deterioration coefficient β is changed from the B state in FIG. 7 to the C state, even if the B state appears due to a calculation error, the temperature correction coefficient α is maintained at α ′ and stable temperature correction is performed. The coefficient α can be obtained. Here, the temperature correction coefficient at the time of deterioration is one kind of α ′, but a plurality of temperature correction coefficients α ′ having different sizes may be set.

上述したステップS6またはステップS8の処理が終了したならば、ステップS9へと進む。ステップS9では、算出された出力劣化係数β(out),容量劣化係数γ(out)および温度補正係数α(out)を、上述した式(4)に適用することで、式(13)に示す補正されたパワー対容量特性Wh(P)が求まる。また、式(14)のように、充電中に得られる入力可能パワーPmax(in)に関するβ(in),γ(in)およびα(in)を用いることで、入力時のパワー対容量特性Wh(P)が求まる。
Wh(P)=Wh1(P/α(out)β(out))×γ(out) …(13)
Wh(P)=Wh1(P/α(in)β(in))×γ(in) …(14)
If the process of step S6 or step S8 is completed, the process proceeds to step S9. In step S9, the calculated output deterioration coefficient β (out), capacity deterioration coefficient γ (out), and temperature correction coefficient α (out) are applied to the above-described expression (4), thereby obtaining the expression (13). A corrected power-capacitance characteristic Wh (P) is obtained. Further, as shown in Expression (14), by using β (in), γ (in), and α (in) regarding the input possible power Pmax (in) obtained during charging, the power-capacitance characteristic Wh at the time of input is obtained. (P) is obtained.
Wh (P) = Wh1 (P / α (out) β (out)) × γ (out) (13)
Wh (P) = Wh1 (P / α (in) β (in)) × γ (in) (14)

ステップS10では、車両として必要な最低保証パワーPminが設定されるとともに、この最低保証パワーPminと算出されたパワー対容量特性Wh(P)とから、Pminに到達するまでの容量Wh(Pmin)が算出される。ステップS11では、次式(15)を用いて容量計6のEMPTYランプ点灯時の容量WhCを算出する。ここで、ΔWhはEMPTY点灯後に保証する電力量であり、EMPTY点灯後もΔWhの分だけ走行ができる。
WhC=Wh(Pmin)−ΔWh …(15)
In step S10, the minimum guaranteed power Pmin required for the vehicle is set, and the capacity Wh (Pmin) until reaching Pmin is calculated from the minimum guaranteed power Pmin and the calculated power-capacitance characteristic Wh (P). Calculated. In step S11, the capacity WhC when the EMPTY lamp of the capacity meter 6 is lit is calculated using the following equation (15). Here, ΔWh is the amount of power guaranteed after EMPTY is lit, and even after EMPTY is lit, the vehicle can travel by ΔWh.
WhC = Wh (Pmin) −ΔWh (15)

ステップS12では、算出された出力可能パワーPmax(out)とパワー対容量特性Wh(P)とから、現在までの放電電力量WhR=Wh(Pmax)を算出する。次いで、ステップS13では、電池の残存容量を次式(16)により算出する。図8は、上述した一連の処理で算出される量(WhC等)の間の関係をパワー対容量特性と対比させて示したものである。
(残存容量)=WhC−WhR …(16)
In step S12, the discharge electric energy WhR = Wh (Pmax) up to the present is calculated from the calculated output possible power Pmax (out) and the power versus capacity characteristic Wh (P). Next, in step S13, the remaining capacity of the battery is calculated by the following equation (16). FIG. 8 shows the relationship between the amounts (WhC, etc.) calculated by the above-described series of processes in comparison with the power-capacitance characteristics.
(Remaining capacity) = WhC−WhR (16)

図9は、電池劣化時に劣化時の値α’を用いた場合と、従来のように初期値α0を用いた場合を比較する図である。電池劣化時においては、曲線L3は温度補正係数αで補正する前のパワー対容量特性を示しており、曲線L4は初期値α0で温度補正した場合のパワー対容量特性を、曲線L4’は劣化時の値α’で温度補正した場合のパワー対容量特性をそれぞれ示している。   FIG. 9 is a diagram comparing the case where the value α ′ at the time of battery deterioration is used and the case where the initial value α0 is used as in the prior art. When the battery deteriorates, the curve L3 shows the power-capacity characteristic before correction with the temperature correction coefficient α, the curve L4 shows the power-capacity characteristic when the temperature is corrected with the initial value α0, and the curve L4 ′ shows the deterioration. The power-capacitance characteristics when the temperature is corrected with the time value α ′ are shown.

図9からも分かるように、温度補正係数αの影響により、曲線L4,L4’と最低保証パワーPminの直線と交わる位置(容量)が異なる。その結果、どちらを採用するかによって走行可能距離が異なることになる。図9に示したケースでは、電池劣化後の走行可能容量の実力値Wh4’に対して、従来手法により求めた走行可能容量Wh4のほうが大きいため、実際に走行できる容量よりもより多くの容量があると車両システムが認識してしまうこととなる。この結果、従来の算出方法を用いると、残容量がほとんど無いにもかかわらず、車両の容量計ではまだ走行できると表示されてしまうことになる。   As can be seen from FIG. 9, the position (capacity) at which the curves L4 and L4 'intersect with the straight line of the minimum guaranteed power Pmin differs due to the influence of the temperature correction coefficient α. As a result, the travelable distance varies depending on which one is adopted. In the case shown in FIG. 9, the available capacity Wh4 obtained by the conventional method is larger than the actual value Wh4 ′ of the operable capacity after battery deterioration. If there is, the vehicle system will recognize it. As a result, when the conventional calculation method is used, it is displayed that the vehicle capacity meter can still travel even though there is almost no remaining capacity.

上述した本実施の形態によれば、以下のような作用効果を奏する。
(1)パワー対容量特性の初期特性Wh(P)を電池温度に基づく温度補正係数αで補正して、温度補正されたパワー対容量特性を算出する電池特性演算装置において、電池の劣化度に応じて温度補正係数αを補正する補正手段5を備え、その補正手段5で補正された温度補正係数α’に基づいて初期特性Wh(P)を補正するようにしたので、パワー対容量特性の精度向上を図ることができる。
(2)判定手段5により、電池の劣化度βが所定の基準値β2を超えていると判定された場合に、温度補正係数αを補正するようにしているので、劣化度に応じて連続的に温度補正係数を変更した場合に生ずる計算のループを防止することができる。
(3)さらに、劣化度減少時の基準値β1と劣化度増大時の基準値β2とを設け、基準値β1を基準値β2より小さく設定し、基準値にヒステリシスを設けるようにしたので、演算誤差により劣化度βにバラツキが生じた場合でも、基準値付近において温度補正係数の変更が頻繁に発生するのを防止することができる。
(4)また、このような電池特性演算装置により算出されたパワー対容量特性に基づいて、電池の容量を算出することで、容量算出の精度を高めることができる。
According to the above-described embodiment, the following operational effects can be obtained.
(1) In the battery characteristic calculation device that calculates the power-capacity characteristic corrected by the temperature correction coefficient α based on the battery temperature by correcting the initial characteristic Wh (P) of the power-capacity characteristic, Accordingly, the correction means 5 for correcting the temperature correction coefficient α is provided, and the initial characteristic Wh (P) is corrected based on the temperature correction coefficient α ′ corrected by the correction means 5, so that the power-capacitance characteristic The accuracy can be improved.
(2) When the determination means 5 determines that the battery degradation level β exceeds the predetermined reference value β2, the temperature correction coefficient α is corrected. It is possible to prevent a calculation loop that occurs when the temperature correction coefficient is changed.
(3) Furthermore, the reference value β1 when the deterioration level is decreased and the reference value β2 when the deterioration level is increased are set, the reference value β1 is set smaller than the reference value β2, and the reference value is provided with hysteresis. Even when the degree of degradation β varies due to an error, it is possible to prevent frequent changes in the temperature correction coefficient in the vicinity of the reference value.
(4) Moreover, the accuracy of capacity calculation can be improved by calculating the capacity of the battery based on the power versus capacity characteristic calculated by such a battery characteristic calculation device.

以上説明した実施の形態と特許請求の範囲の要素との対応において、演算装置5は補正手段および判定手段を構成する。なお、以上の説明はあくまでも一例であり、発明を解釈する際、上記実施の形態の記載事項と特許請求の範囲の記載事項の対応関係に何ら限定も拘束もされない。   In the correspondence between the embodiment described above and the elements of the claims, the arithmetic unit 5 constitutes a correction unit and a determination unit. The above description is merely an example, and when interpreting the invention, there is no limitation or restriction on the correspondence between the items described in the above embodiment and the items described in the claims.

本発明による電池容量演算装置の一実施の形態を説明するブロック図である。It is a block diagram explaining one Embodiment of the battery capacity calculating apparatus by this invention. パワー対容量特性の補正方法を示す図であり、(a)は初期時の補正を示し、(b)劣化時の補正を示す。It is a figure which shows the correction method of a power versus capacity | capacitance characteristic, (a) shows correction | amendment at the time of initial stage, (b) shows correction | amendment at the time of deterioration. 最低保証出力と容量との関係を示す図である。It is a figure which shows the relationship between the minimum guarantee output and a capacity | capacitance. 演算部51で処理される残存容量算出の手順を示すフローチャートである。4 is a flowchart showing a procedure for calculating a remaining capacity to be processed by a calculation unit 51. 回帰直線を説明する図であり、(a)は放電時を、(b)は充電時を示す。It is a figure explaining a regression line, (a) shows the time of discharge, (b) shows the time of charge. 劣化補正係数βの変化に対する初期値α0および劣化時の値α’の変化を示す図である。It is a figure which shows the change of the initial value (alpha) 0 with respect to the change of the degradation correction coefficient (beta), and the value (alpha) 'at the time of degradation. 出力劣化係数β(out)と温度補正係数α(out),α’(out)との関係を示す図である。It is a figure which shows the relationship between output degradation coefficient (beta) (out) and temperature correction coefficient (alpha) (out), (alpha) '(out). 残存容量の算出を説明する図である。It is a figure explaining calculation of remaining capacity. 温度補正係数αとして劣化時の値α’を用いた場合と初期値α0を用いた場合の、走行可能容量への影響を説明する図である。It is a figure explaining the influence on the driving | running | working capacity | capacitance at the time of using the value (alpha) 'at the time of deterioration as a temperature correction coefficient (alpha), and using the initial value (alpha) 0.

符号の説明Explanation of symbols

1:電池、2:温度センサ、3:電圧検出部、4:電流検出部、5:演算装置、6:容量計、51:演算部、52:記憶部   1: battery, 2: temperature sensor, 3: voltage detection unit, 4: current detection unit, 5: arithmetic unit, 6: capacity meter, 51: arithmetic unit, 52: storage unit

Claims (3)

パワー対容量特性の初期特性を電池温度に基づく温度補正係数で補正して、温度補正されたパワー対容量特性を算出する電池特性演算装置において、
電池の劣化度が所定の基準値を超えているか否かを判定する判定手段と、
劣化度増大時と劣化度減少時とで前記基準値を異ならせ、劣化度減少時の基準値を劣化度増大時の基準値より小さく設定する設定手段と、
前記判定手段により前記基準値を超えていると判定されると、電池の劣化度に応じて前記温度補正係数を補正する補正手段と、を備え、
前記補正手段で補正された温度補正係数に基づいて前記初期特性を補正することを特徴とする電池特性演算装置。
In the battery characteristic calculation device for calculating the temperature-corrected power-capacity characteristic by correcting the initial characteristic of the power-capacity characteristic with a temperature correction coefficient based on the battery temperature,
Determining means for determining whether or not the degree of deterioration of the battery exceeds a predetermined reference value;
Setting means for setting the reference value when the deterioration degree is decreased to be smaller than the reference value when the deterioration degree is increased, by making the reference value different when the deterioration degree is increasing and when the deterioration degree is decreasing;
If it is determined to exceed the reference value by the determination means, and correcting means for correcting the temperature correction coefficient according to the deterioration degree of the battery, the provided,
A battery characteristic calculation device that corrects the initial characteristic based on a temperature correction coefficient corrected by the correction means.
請求項1に記載の電池特性演算装置において、
前記劣化度は、前記電池の内部抵抗の変化に基づいて算出されることを特徴とする電池特性演算装置。
In the battery characteristic calculation device according to claim 1,
The battery characteristic calculation device, wherein the deterioration degree is calculated based on a change in internal resistance of the battery.
請求項1または2に記載の電池特性演算装置により算出されたパワー対容量特性に基づいて、電池の容量を算出することを特徴とする電池容量演算装置。 Based on the power versus capacity characteristic calculated by the battery characteristic calculation apparatus according to claim 1 or 2, the battery capacity calculation unit and calculates the capacity of the battery.
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