JP2007003438A - Charging rate estimation device for secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a charging rate estimation device for a secondary battery capable of reducing delay of an internal resistance estimated value, when the actual internal resistance is increased by a phenomenon in which internal resistance is increased by delay of electron delivery between positive and negative electrodes during discharge of large current from a secondary battery. <P>SOLUTION: The charging rate estimation device for the secondary battery has at least one of an adjusting means for correcting it so as to increase the adjusting gain λ<SB>3</SB>for adjusting estimated rate in a parameter estimation arithmetic means 4 and an adjusting means for correcting it so as to speed up the responsiveness in a low pass filter processing section and band pass filter processing section, when a measured current value (for example, its absolute value when charge direction is set positive and discharge direction is set negative) lies in a region ((a) or more of Fig. 6) where the internal resistance value of the secondary battery becomes larger than a predetermined value. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an apparatus for estimating a charging rate (SOC) of a secondary battery.

Battery charging rate SOC (also referred to as a state of charge) is _(a battery terminal voltage during energization blocking, electromotive force, also referred to as open circuit voltage) open-circuit voltage V ₀ so that there is a correlation, by obtaining the open-circuit voltage V ₀ The charge rate can be estimated. However, since it takes time to stabilize the terminal voltage of the secondary battery even after the energization is cut off (end of charge / discharge), in order to obtain an accurate open circuit voltage V ₀ , a predetermined voltage is required after the end of charge / discharge. Time is required. Therefore, during charging / discharging or immediately after charging / discharging, an accurate open circuit voltage V ₀ cannot be obtained, and thus the charging rate SOC cannot be obtained by the above method. Therefore, conventionally, as described in Patent Document 1, for example, an adaptive digital filter is used to detect the current and terminal voltage of a secondary battery (a chargeable / dischargeable battery such as a lead battery or a lithium ion battery) that is energized. A battery model parameter is estimated (identified) using (also referred to as an adaptive filter), an open circuit voltage is estimated using the estimated parameter, and a charging rate SOC is calculated based on this value.
In Patent Document 1, in order to improve the followability of the open circuit voltage estimation, the adjustment gain of the estimated speed in the adaptive digital filter is increased and corrected from the size of the internal resistance estimated value. The adjustment gain of the estimated speed determines a change range from the previous estimated value for bringing the parameter estimated value at the previous calculation closer to the current parameter actual value in the calculation algorithm. When the adjustment gain is large, the speed at which the parameter estimated value follows the actual value increases, but the parameter estimated value becomes variable because the overshoot amount increases due to the influence of observation noise. Conversely, when the adjustment gain is small, the speed at which the parameter estimation value follows the actual value is slow, but the parameter estimation value is stable because the overshoot amount is small even when affected by the observation noise. Therefore, there is an optimum value for the adjustment gain in order to maintain good estimation accuracy and speed under a certain observation noise environment. Therefore, it is not a good idea to set the adjustment gain large in advance because the estimation accuracy deteriorates due to the influence of observation noise.

JP 2004-14231 A

When the secondary battery discharges a large current, it appears as a battery-specific phenomenon that the internal resistance increases due to the fact that the transfer of electrons between the positive and negative electrodes can no longer catch up. However, the conventional example is configured to determine the adjustment gain of the adaptive digital filter from the magnitude of the estimated internal resistance. For this reason, when the actual internal resistance increases due to a phenomenon inherent to the battery during a large current discharge as described above, the increase in adjustment gain is delayed when the follow-up of the estimated internal resistance is delayed relative to the actual increase in internal resistance. Therefore, there is a problem that the follow-up of the internal resistance estimated value and the actual value is further delayed, resulting in a delay in the charging rate estimation.
The present invention has been made in order to solve the above-described problem. When the actual internal resistance is increased due to a phenomenon inherent to the battery during large current discharge, the secondary resistance that can reduce the delay of the estimated internal resistance can be reduced. It aims at providing the charging rate estimation apparatus of a battery.

  In order to achieve the above object, in the present invention, the measured current value (for example, the absolute value when the charging direction is positive and the discharging direction is negative) is such that the internal resistance value of the secondary battery is lower than a predetermined value. When in the increasing region, the adjustment means for correcting the adjustment speed for adjusting the estimated speed in the parameter estimation calculation means to be increased, and the responsiveness in the low-pass filter processing section and the band-pass filter processing section are made faster. It comprises so that at least one of the adjustment means to correct | amend may be provided. That is, it is detected from the measured current value that there is a current value in a region where the internal resistance increases, and in that region, adjustment gain is increased or adjustment is performed so as to increase the responsiveness of the filter.

  When there is a current value in a region where the internal resistance increases, the configuration is such that the adjustment gain is increased or the filter responsiveness is increased, so that the actual internal resistance increases during large current discharge. Thus, the delay of the estimated internal resistance can be reduced. Therefore, there is an effect that delay in charging rate estimation can be reduced.

FIG. 1 is a functional block diagram showing an embodiment of the present invention. In FIG. 1, 1 is a current I (k) detection means for detecting the current of a secondary battery (hereinafter simply referred to as a battery), 2 is a terminal voltage V (k) detection means for detecting the terminal voltage of the battery, Preprocessing filter calculation means, 4 is a parameter θ (k) estimation calculation means, 5 is an open circuit voltage calculation means [calculates V ₀ (k)], 6 is a charge rate estimation means for calculating the charge rate SOC from the open circuit voltage, 7 Is an adjusting means. The preprocessing filter calculation means 3 is composed of a low pass filter and a band pass filter which will be described later. The adjustment means 7 has a function (details will be described later) for adjusting the adjustment gain λ ₃ (k) and the response p (k) of the filter according to the current value obtained by the current I (k) detection means. The combined portion of the preprocessing filter calculation means 3 and the parameter θ (k) estimation calculation means 4 constitutes an adaptive digital filter calculation means.

FIG. 2 is a block diagram illustrating a specific configuration of the embodiment. This embodiment shows an example in which a secondary battery charge rate estimation device is provided in a system that drives a load such as a motor with a secondary battery or charges a secondary battery with regenerative power of the motor.
In FIG. 2, 10 is a secondary battery (also simply called a battery), 20 is a load of a motor, etc., 30 is an electronic control unit that estimates the state of charge of the battery, a CPU that calculates a program, a ROM that stores a program, and a calculation It consists of a microcomputer composed of a RAM for storing the results and an electronic circuit. Reference numeral 40 denotes an ammeter that detects current charged / discharged from the battery, 50 denotes a voltmeter that detects the terminal voltage of the battery, and 60 denotes a thermometer that detects the temperature of the battery, each connected to the electronic control unit 30. The electronic control unit 30 corresponds to the preprocessing filter calculation means 3, the parameter θ (k) estimation calculation means 4, the open circuit voltage calculation means 5, the charging rate estimation means 6 and the adjustment means 7 of FIG. The ammeter 40 corresponds to the current I (k) detecting means 1 and the voltmeter 50 corresponds to the terminal voltage V (k) detecting means 2.
In the present invention, an open circuit voltage V ₀ is estimated by using an adaptive digital filter in the measurement data of the terminal voltage V and current I of the energized secondary battery, and charging is performed from the relationship between the known open circuit voltage V ₀ and the charge rate SOC. This is a device for estimating the rate, and the battery model of the secondary battery is defined as shown in the equation (1).

The above contents will be specifically described as follows.
First, the “battery model” used in the present embodiment will be described. FIG. 3 is a diagram showing an equivalent circuit model of the secondary battery, and the battery model of the secondary battery is expressed by the following equation (Equation 2).

（数２）式において、モデル入力は電流Ｉ［Ａ］（正値は充電、負値は放電）、モデル出力は端子電圧Ｖ［Ｖ］、Ｒ_１〔Ω］は電荷移動抵抗、Ｒ_２［Ω］は純抵抗、Ｃ_１［Ｆ］は電気二重層容量、Ｖ_０［Ｖ］は開路電圧である。なお、ｓはラプラス演算子である。本モデルは、正極、負極を特に分離していないリダクションモデル（一次）であるが、実際の電池の充放電特性を比較的正確に示すことが可能である。このように本実施例においては、電池モデルの次数を１次にした構成を例として説明する。なお、前記（数１）式は電池モデルの一般式である。

In the equation (2), the model input is current I [A] (positive value is charging, negative value is discharging), model output is terminal voltage V [V], R ₁ [Ω] is charge transfer resistance, R ₂ [ Ω] is a pure resistance, C ₁ [F] is an electric double layer capacitance, and V ₀ [V] is an open circuit voltage. Note that s is a Laplace operator. Although this model is a reduction model (primary) in which the positive electrode and the negative electrode are not particularly separated, it is possible to show the actual charge / discharge characteristics of the battery relatively accurately. As described above, in this embodiment, a configuration in which the order of the battery model is first will be described as an example. In addition, the said (Formula 1) type | formula is a general formula of a battery model.

Derivation from the battery model of the above (Equation 2) to the adaptive digital filter will be described first.
When formula (2) is modified, formula (3) is obtained.

上記のように、電池パラメータＫ＝Ｒ_１＋Ｒ_２であって、これは電池モデルの内部抵抗推定値に相当する。
開路電圧Ｖ_０は、電流Ｉに可変な効率ｄを乗じたものを、ある初期状態から積分したものと考えれば、（数４）式で書ける。

As described above, the battery parameter K = R ₁ + R ₂ , which corresponds to the estimated internal resistance value of the battery model.
The open circuit voltage V ₀ can be expressed by the following equation (4), assuming that the current I multiplied by the variable efficiency d is integrated from a certain initial state.

（数４）式を（数３）式に代入すれば（数５）式になり、整理すれば（数６）式になる。

Substituting (Equation 4) into (Equation 3) gives (Equation 5), and rearranging it gives (Equation 6).

安定なローパスフィルタＧ_ｌｐ(ｓ)を（数６）式の両辺に乗じて、整理すれば（数７）式になる。

If a stable low-pass filter G _lp (s) is multiplied by both sides of Equation (6) and rearranged, Equation (7) is obtained.

実際に計測可能な電流Ｉや端子電圧Ｖに、ローパスフィルタやバンドパスフィルタを処理した値を、下記（数８）式のように定義する。

A value obtained by processing a low-pass filter or a band-pass filter on the current I or the terminal voltage V that can be actually measured is defined as the following equation (8).

なお、Ｇ_ｌｐ(ｓ)はローパスフィルタ、ｓ・Ｇ_ｌｐ(ｓ)やｓ^２・Ｇ_ｌｐ(ｓ)はバンドパスフィルタである。
上記変数を用いて（数７）式を書き直せば（数９）式になる。

G _lp (s) is a low-pass filter, and s · G _lp (s) and s ² · G _lp (s) are band-pass filters.
If equation (7) is rewritten using the above variables, equation (9) is obtained.

更に変形すれば（数１０）式になる。

If further deformed, the formula (10) is obtained.

（数１０）式は、計測可能な値と未知パラメータの積和式になっているので、一般的な適応デジタルフィルタの標準形（数１１）式と一致する。

Since (Equation 10) is a product-sum equation of a measurable value and an unknown parameter, it agrees with a standard form (Equation 11) of a general adaptive digital filter.

ただし、ｙ＝Ｖ_２、 ω^Ｔ＝［Ｖ_３，Ｉ_３，Ｉ_２，Ｉ_１］
θ^Ｔ＝［−Ｔ_１，Ｋ・Ｔ_２，Ｋ，ｄ］
従って、電流Ｉと端子電圧Ｖにフィルタ処理した信号を、適応デジタルフィルタ演算に用いることで、未知パラメータベクトルθを推定する。本実施例では、単純な「最小二乗法による適応デジタルフィルタ」の論理的な欠点（一度推定値が収束すると、その後パラメータが変化しても再度正確な推定ができないこと）を改善した「両限トレースゲイン方式」を用いる。
（数１１）式を前提に未知パラメータベクトルθを推定するためのパラメータ推定アルゴリズムは下記（数１２）式となる。ただし、ｋ時点のパラメータ推定値をθ(ｋ)とする。

However, y = V ₂ , ω ^T = [V ₃ , I ₃ , I ₂ , I ₁ ]
θ ^T = [− T ₁ , K · T ₂ , K, d]
Therefore, the unknown parameter vector θ is estimated by using the signal filtered to the current I and the terminal voltage V for the adaptive digital filter calculation. In this example, the logical disadvantage of a simple “adaptive digital filter based on the least square method” (because once the estimated value converges, accurate estimation cannot be performed again even if the parameter changes) is improved. "Trace gain method" is used.
A parameter estimation algorithm for estimating the unknown parameter vector θ based on the equation (11) is expressed by the following equation (12). However, the parameter estimated value at the time point k is θ (k).

ただし、λ_１、λ_３(ｋ)、γ_Ｕ、γ_Ｌは初期設定値で、０＜λ_１＜１、０＜λ_３(ｋ)＜∞とする。Ｐ(０)は十分大きな値、θ(０)は非ゼロな十分小さな値を初期値とする。trace｛Ｐ｝は行列Ｐのトレースを意味する。
本発明では、電流値に応じて調整ゲインλ_３(ｋ)を補正する。なお、或る観測ノイズの環境下で推定精度を良好に保つには、適応デジタルフィルタの推定感度を調節する定数であるλ_３(ｋ）（調整ゲイン）には上限がある。そのため、調整ゲインを予め大きく設定しておくのは、上限までのマージンが小さくなるので、観測ノイズの影響を受けて推定精度が悪化するため得策でない。
また、ローパスフィルタＧ_ｌｐ(ｓ）の設定に関しては、（数１２）式のパラメータ推定アルゴリズムの推定精度を良くするために、観測ノイズを低減するようローパスフィルタの応答性（カットオフ周波数特性）を適切に設定するけれども、電池の応答特性よりは速くする。以上が、電池モデルから適応デジタルフィルタまでの導出である。

However, λ ₁ , λ ₃ (k), γ _U , γ _L are initial setting values, and 0 <λ ₁ <1, 0 <λ ₃ (k) <∞. P (0) is a sufficiently large value, and θ (0) is a non-zero sufficiently small value as an initial value. trace {P} means the trace of the matrix P.
In the present invention, the adjustment gain λ ₃ (k) is corrected according to the current value. In order to maintain good estimation accuracy under certain observation noise environments, λ ₃ (k) (adjustment gain), which is a constant for adjusting the estimation sensitivity of the adaptive digital filter, has an upper limit. Therefore, it is not a good idea to set the adjustment gain large in advance because the margin up to the upper limit is small, and the estimation accuracy deteriorates due to the influence of observation noise.
Further, regarding the setting of the low-pass filter G _lp (s), in order to improve the estimation accuracy of the parameter estimation algorithm of the equation (12), the response of the low-pass filter (cut-off frequency characteristic) is reduced so as to reduce the observation noise. Although set appropriately, it is faster than the battery response characteristics. The above is the derivation from the battery model to the adaptive digital filter.

In the above description, the case where the order of the battery model is set to 1 has been described as an example, so that the internal resistance estimated value K = R ₁ + R ₂ is used. However, in the case of the general formula shown by the formula (1) The estimated internal resistance is b ₀ / a ₀ . That is, in the equation (1), a ₀ and b ₀ represent values in the steady state of the polynomials A (s) and B (s). Since it is considered that the Labruss operator s = 0 in a steady state, the above (Equation 1) can be transformed into the following equation.
V = (b ₀ / a ₀ ) I + V ₀ / a ₀
In addition, when the order of the battery model is set to primary, the expression (equation 2) corresponding to the expression (equation 1) of the general expression is as follows when s = 0.
V = (R ₁ + R ₂ ) · I + V ₀ = K · I + V ₀
When the above two expressions are compared, K = b ₀ / a ₀ . As described in the above equation (3), the battery parameter K = R ₁ + R ₂ , which corresponds to the estimated internal resistance value of the battery model. Therefore, the estimated internal resistance value in the case of the general formula is b _0. It can be seen that / a ₀ is obtained.

Next, FIG. 4 is a flowchart of processing performed by the microcomputer of the electronic control unit 30. In this embodiment, the order of the battery model is first. Note that the routine of FIG. 4 is performed every predetermined period T _0. For example, I (k) represents the current calculated value, and I (k−1) represents the previous calculated value.
First, in step S10, the current I (k) and the terminal voltage V (k) are measured.
In step S20, the secondary battery cutoff relay is determined. The electronic control unit 30 also controls the secondary battery cutoff relay, and when the relay is cut off (current I = 0), the process proceeds to step S30. When the relay is engaged, the process proceeds to step S40.

In step S30, the terminal voltage V (k) is stored as the terminal voltage initial value V_ini.
In step S40, a terminal voltage difference value ΔV (k) is calculated.
However, ΔV (k) = V (k) −V_ini
This is because the initial value of the estimation parameter in the adaptive digital filter is set to about 0, so that all the inputs are set to 0 so that the estimation parameter does not diverge when the estimation calculation starts. Since the process goes through step S30 when the relay is cut off, since I = 0 and ΔV (k) = 0, the estimation parameters remain in the initial state.

In step S50, the low-pass filter G _lp (s), the band-pass filters s · G _lp (s) and s ^{2 are} added to the current I (k) and the terminal voltage difference value ΔV (k) based on the equation (8). _-Filter processing of G _lp (s) is performed, and I ₁ , I ₂ , I ₃ , V ₂ , and V ₃ are calculated as shown in the following (Equation 13). In order to improve the estimation accuracy of the parameter estimation algorithm expressed by the equation (12), the response of the low-pass filter G _lp (s) is set so as to reduce the observation noise. However, it is faster than the response characteristics of the battery. P in the equation (13) is a constant (time constant) that determines the response of G _lp (s).

ステップＳ６０では、図６に示す内部抵坑値Ｋが増大する領域に電流値があるか否かで、（数１２）式のパラメータ推定アルゴリズムの調整ゲインλ_３(ｋ）を補正するか否かを判定する。つまり電流値Ｉの絶対値（例えば充電方向を正、放電方向を負とする）が所定値ａより小の領域１は補正が不要な通常領域であり、電流値Ｉが所定値ａ以上の領域２は内部抵坑値Ｋが増大する領域であって補正が必要と判断する。
｜Ｉ(ｋ）｜＜ａなる場合、補正が不要と判断してステップＳ８０へ進む。
｜Ｉ(ｋ）｜≧ａなる場合、補正が必要と判断してステップＳ７０へ進む。

In step S60, whether or not the adjustment gain λ ₃ (k) of the parameter estimation algorithm of equation (12) is corrected is determined depending on whether or not there is a current value in a region where the internal resistance value K shown in FIG. 6 increases. Determine. That is, the region 1 in which the absolute value of the current value I (for example, the charging direction is positive and the discharging direction is negative) is smaller than the predetermined value a is a normal region that does not require correction, and the current value I is the predetermined value a or more. 2 is an area where the internal resistance value K increases, and it is determined that correction is necessary.
If | I (k) | <a, it is determined that correction is unnecessary, and the process proceeds to step S80.
If | I (k) | ≧ a, it is determined that correction is necessary, and the process proceeds to step S70.

In step S70, since there is a current value in a region where the internal resistance value K increases, the estimated speed is slow with a normal adjustment gain, so the adjustment gain λ ₃ (k) is corrected to a value increased by 50% from the initial value. At this time, the correction value may be a single value as described above, or, as shown in FIG. 7, the adjustment gain λ ₃ (corresponding to the internal resistance value K that increases according to the current value (absolute value). If the value k) is gain-scheduled and mapped, and corrected to a value read from the map according to the current value at that time, finer correction can be made.

In addition, the time for correcting the adjustment gain λ ₃ (k) is set to a predetermined time from the time when the current value enters the region where the internal resistance value K increases, or the predetermined time from the time when the current value returns to the normal region. If the configuration is limited, it is possible to prevent fluctuations in the parameter estimation value due to the large adjustment gain after the parameter estimation value follows the actual value.

In step S80, since there is no current value in the region where the internal resistance value increases, the initial value of λ ₃ (k), which is a normal adjustment gain, is used.
In step S90, I ₁ (k), I ₂ (k), I ₃ (k), V ₂ (k), and V ₃ (k) calculated in step S50 are substituted into the equation (12). Then, a parameter estimation algorithm (adaptive digital filter calculation) (Expression 12) is performed to calculate a parameter estimated value θ (k).
However, y = V ₂ , ω ^T = [V ₃ , I ₃ , I ₂ , I ₁ ], θ ^T = [− T ₁ , K · T ₂ , K, d].

In step S100, G _lp is calculated based on the equation (equation 14) equivalent to the equation (3) using T ₁ , K · T ₂ , and K from the parameter estimated values θ (k) calculated in step S90. (s) · V ₀ is calculated and used as a substitute for the open circuit voltage V ₀ . Since the open circuit voltage V ₀ changes slowly, G _lp (s) · V ₀ can be used instead. However, what is obtained here is a change ΔV ₀ (k) of the open circuit voltage estimated value from the start of the estimation calculation.

ステップＳ１１０では、ステップＳ１００で算出した△Ｖ_０(ｋ）はアルゴリズム開始時からの開路電圧の変化分であるから、開路電圧初期値すなわち端子電圧初期値Ｖ_iniを加算して開路電圧推定値Ｖ_０(ｋ）を（数１５）式で算出する。
Ｖ_０(ｋ）＝△Ｖ_０(ｋ）＋Ｖ_ini …（数１５）
ステップＳ１２０では、図５に示す開路電圧と充電率の相関マップを用いて、ステップＳ１１０で算出したＶ_０(ｋ）から充電率ＳＯＣ(ｋ）を算出する。
なお、図５のＶＬはＳＯＣ＝０％に、ＶＨはＳＯＣ＝１００％に相当する開路電圧である。
ステップＳ１３０では、次回演算に必要な数値を保存して、今回演算を終了する。

In step S110, since ΔV ₀ (k) calculated in step S100 is a change in the open circuit voltage from the start of the algorithm, the open circuit voltage initial value, that is, the terminal voltage initial value V_ini is added to determine the open circuit voltage estimated value V _0. (k) is calculated by the equation (15).
V ₀ (k) = ΔV ₀ (k) + V_ini (Equation 15)
In step S120, the charging rate SOC (k) is calculated from V ₀ (k) calculated in step S110, using the correlation map between the open circuit voltage and the charging rate shown in FIG.
Note that VL in FIG. 5 is an open circuit voltage corresponding to SOC = 0% and VH is SOC = 100%.
In step S130, numerical values necessary for the next calculation are stored, and the current calculation ends.

6 and 7 are characteristic diagrams showing the relationship between the current value I and the internal resistance value K. FIG. 6 shows a region corresponding to the current value as a normal region 1 and a region 2 where the internal resistance value increases. FIG. 7 shows a case where the region where the internal resistance value increases is divided into three regions 2, 3, and 4.
In the case of FIG. 6, the normal region 1 and the region 2 in which the internal resistance value increases are divided into two according to the current value. No correction is made in the normal region 1, and + 50% increase correction with respect to the normal gain in the region 2. It is carried out.

  In the case of FIG. 7, as shown in the illustrated map area and adjustment gain correction example, in the normal area 1 where there is no increase in internal resistance, there is no correction for the normal gain, and the area 2 where the increase in the internal shaft begins. Is + 10% increase correction with respect to the normal gain, + 25% increase correction with respect to the normal gain in the region 3 where the increase in internal resistance is large, and + 50% increase with respect to the normal gain in the region 4 where the increase in internal resistance is further increased Like correction, the adjustment gain is finely corrected according to the map area. For this reason, in areas where the degree of increase is large, the adjustment gain is made sufficiently large so that the estimated internal resistance value follows quickly, and in areas where the degree of increase is small, the adjustment gain is increased slightly to suppress unnecessary fluctuations in the internal resistance estimated value. However, the tracking delay can be reduced.

8 and 9 are time charts showing values of current, internal resistance, and adjustment gain in the calculation of the present invention. FIG. 8 shows a case where the adjustment gain is corrected in one step as shown in FIG. Shows a case where the adjustment gain is corrected in multiple stages as shown in FIG.
In FIG. 8, in the conventional example, even when the current value is in a region (A in the figure) larger than the predetermined value a at which the actual internal resistance starts to increase, the adjustment gain increase correction determined from the internal resistance estimated value cannot be corrected. Therefore (C in the figure), there is a problem that the estimated internal resistance has a large follow-up delay to the actual value (B in the figure). However, in the first embodiment (characteristic shown in FIG. 6), when the current value is in a region (A in the figure) larger than the predetermined value a where the actual increase in internal resistance starts, the adjustment gain is determined from the current value. Is increased (C in the figure), the internal resistance estimated value has an effect that the follow-up delay to the actual value becomes very small (B in the figure).

  In FIG. 9, in the first embodiment (characteristic shown in FIG. 6), in the region larger than the current value b (D in the figure) where the actual increase degree of the internal resistance is greatly increased (D in the figure), the adjustment gain determined from the current value is increased. The correction cannot reflect the degree and a sufficient magnitude cannot be obtained (F in the figure), and the internal resistance estimation value has a slightly large follow-up delay to the actual value (E in the figure). However, in the second embodiment (characteristic shown in FIG. 7), in the region larger than the current value b (D in the figure) where the actual increase degree of the internal resistance is greatly increased (D in the figure), the adjustment gain increase correction determined from the current value is Reflecting the degree, a sufficient size is obtained (F in the figure), and the internal resistance estimation value has a very small follow-up delay to the actual value (E in the figure).

Further, as shown in FIGS. 8 and 9, when the adjustment gain is largely corrected only for a predetermined time τ ₁ from the time point t ₁ when the current value enters the region where the actual internal resistance value increases. Has an effect that the fluctuation of the parameter estimated value due to the influence of the observation noise can be suppressed after the parameter estimated value follows the actual value. Also, when returning from the region where the internal resistance has increased to the normal region, if the adjustment gain is largely corrected only during the predetermined time τ ₂ from the time t ₂ when the internal resistance has increased, the actual internal resistance increases. When returning from the normal state to the normal state, it is possible to prevent a follow-up delay of the internal resistance estimation value. Note that the values of τ ₁ and τ ₂ may be τ ₁ = τ ₂ or τ ₁ ≠ τ ₂ and may be set according to the characteristics of the secondary battery and the configuration of the estimation device.

In the above description, when the current value is in a region larger than the predetermined value at which the actual internal resistance starts to increase, the correction is performed so that the adjustment gain λ ₃ for adjusting the estimated speed of the parameter estimation calculation is increased. However, instead, correction may be made so that the responsiveness of the low-pass filter and the band-pass filter is increased (p in Equation 13 is reduced). Alternatively, both may be corrected so that the adjustment gain is increased and the responsiveness of the low-pass filter and the band-pass filter is increased. Thus, by increasing the responsiveness of the filter, the response delay due to the filter processing is reduced, and the delay of the internal shaft estimated value can be reduced with respect to the phenomenon in which the actual internal resistance increases. is there.

The figure which represented one Example of this invention with the functional block. The block diagram which shows the specific structure of an Example. The figure which shows the equivalent circuit model of a secondary battery. The flowchart of the process in an Example. The characteristic view which shows the relationship between an open circuit voltage and a charging rate. The characteristic view which shows the relationship between an electric current value and internal resistance. The characteristic figure which shows the relationship between an electric current value and internal resistance, and the graph which shows the characteristic of a map area | region and adjustment gain. The time chart 1 which shows the relationship between an electric current value, an internal resistance value, and an adjustment gain. The time chart 2 which shows the relationship between an electric current value, an internal resistance value, and an adjustment gain.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Current I (k) detection means 2 ... Terminal voltage V (k) detection means 3 ... Pre-processing filter calculation means 4 ... Parameter (theta) (k) estimation calculation means 5 ... Open circuit voltage calculation means 6 ... Charging rate estimation means 7 ... Adjustment means 10 ... secondary battery 20 ... load 30 ... electronic control unit 40 ... ammeter 50 ... voltmeter 60 ... thermometer

Claims (4)

A measuring means for measuring the current and terminal voltage of the secondary battery,
A pre-processing filter calculation unit that includes a low-pass filter processing unit and a band-pass filter processing unit, and performs low-pass filter processing and band-pass filter processing on the current and terminal voltage measured by the measuring unit;
Parameter estimation calculation means for inputting the filtered current and terminal voltage to an adaptive digital filter using the battery model shown in (Equation 1), and collectively estimating the parameters in (Equation 1);
An open circuit voltage calculation means for estimating an open circuit voltage from an estimated value of the parameter estimation calculation means;
Charge rate estimating means for estimating the charge rate from the estimated open circuit voltage based on the relationship between the open circuit voltage and the charge rate obtained in advance,
Further, when the absolute value of the measured current value is in a region where the internal resistance value of the secondary battery is larger than a predetermined value, the adjustment gain for adjusting the estimated speed in the parameter estimation calculating means is increased. A charging rate estimation device for a secondary battery, characterized in that it comprises at least one of an adjusting unit for correcting to a high speed and an adjusting unit for correcting so as to increase the responsiveness in the low-pass filter processing unit and the band-pass filter processing unit. .

Where s is a Laplace operator, A (s), B (s), and C (s) are polynomial functions of s, and the order is n   The adjustment means has a map that defines a degree of increasing the adjustment gain according to a degree of increase in the internal resistance value of the secondary battery with respect to a current value or a map that defines a degree of speeding up the responsiveness. 2. The secondary according to claim 1, wherein in the region where the internal shaft value increases from a predetermined value, the map is corrected so as to increase the adjustment gain or speed up the response according to the current value. Battery charge rate estimation device.   The adjustment means increases the adjustment gain or speeds up the responsiveness for a predetermined time from the time when the current value enters a region where the internal resistance value of the secondary battery increases from a predetermined value. The charging rate estimation device for a secondary battery according to claim 1 or 2.   The adjusting means increases the adjustment gain or accelerates the responsiveness for a predetermined time from the time when the current value returns from the region where the internal resistance value of the secondary battery increases from the predetermined value to the normal region. The charging rate estimation device for a secondary battery according to any one of claims 1 to 3, wherein:

Images