JP2005345254A - Residual capacity arithmetic unit for charge accumulating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To uniformly and precisely find a residual capacity all the time by evading influences of accumulation of errors due to current integration and load fluctuation. <P>SOLUTION: A reference residual capacity SOCV(t) is calculated on the basis of an estimated value of a release voltage of a battery, a difference DSOCB between the reference residual capacity SOCV(t) and a residual capacity SOC(t-1) before one computation period is saturated within a limit width using upper and lower limiters set based on a battery current, the saturated residual capacity variation DSOC is added to the residual capacity SOC(t-1) before the one computation period to calculate the final residual capacity SOC(t). The accumulation of errors due to the current integration is eliminated thereby, and vibration due to the load fluctuation of the reference residual capacity SOCV is restrained thereby without accelerating a delay component, to find uniformly and precisely find the residual capacity all the time. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a remaining capacity calculation device for a power storage device that calculates the remaining capacity of a power storage device such as a secondary battery or an electrochemical capacitor.

  In recent years, energy storage devices such as secondary batteries such as nickel metal hydride batteries and lithium ion batteries, and electrochemical capacitors such as electric double layer capacitors have been reduced in size and weight, and energy density has increased. It is actively used as a power source for automobiles.

  In order to effectively use such an electricity storage device, it is important to accurately grasp its remaining capacity. Conventionally, a technique for calculating the remaining capacity by accumulating the charge / discharge current of the electricity storage device and an open circuit voltage are used. A technique for obtaining the remaining capacity based on this is known.

  For example, in Patent Document 1, the remaining capacity at the time of stoppage is obtained from the open-circuit voltage obtained from the battery voltage at the time of stopping the electric vehicle, and the discharge electric capacity is detected based on the integrated value of the discharge current of the battery. A technique is disclosed in which a full charge capacity is calculated from the electric capacity and the remaining capacity at stop, and the remaining capacity is obtained from the full charge capacity and the discharge electric capacity.

  Further, in Patent Document 2, a battery capacity and a battery voltage, such as a lithium ion battery, having a linear proportional relationship, an accumulated amount of current when discharging or charging for an arbitrary time, and discharging or charging. A technique for obtaining a remaining capacity from a previous voltage, a voltage after discharge or a charge is disclosed.

Further, Patent Document 3 discloses a method for calculating the remaining capacity based on the rate of change of the difference between the remaining capacity obtained by integrating the charging / discharging current of the battery and the remaining capacity estimated based on the open terminal voltage of the battery. A technique for correcting the above is disclosed.
JP-A-6-242193 JP-A-8-179018 Japanese Patent Laid-Open No. 11-223665

  However, the technology for obtaining the remaining capacity by integrating the charge / discharge current and the technology for obtaining the remaining capacity based on the estimated open circuit voltage have advantages and disadvantages, respectively, while the former is strong against load fluctuations such as inrush current, There is a drawback that errors tend to accumulate (especially when the load is high, the error becomes large). In the latter case, an accurate value can be obtained during normal use, but the load fluctuates greatly in a short time. In this case, there is a drawback that the calculated value is likely to fluctuate.

  Therefore, as in Patent Documents 1, 2, and 3, it is difficult to eliminate error accumulation due to current integration simply by combining both techniques. In particular, in a state where charging / discharging continues, such as in a hybrid vehicle, there is a possibility that the calculation accuracy of the remaining capacity may be reduced or the calculation value of the remaining capacity may change abruptly, ensuring uniform accuracy. It is difficult.

  The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a remaining capacity calculation device for a power storage device that can avoid the accumulation of errors due to current integration and the influence of load fluctuations and can always obtain a uniform and highly accurate remaining capacity. It is intended to provide.

  In order to achieve the above object, an apparatus for calculating a remaining capacity of an electricity storage device according to the present invention includes a first remaining capacity calculation unit that calculates a remaining capacity based on an estimated value of an open circuit voltage of the electricity storage device as a reference remaining capacity, Limiter setting means for setting a limiter for limiting the amount of change in the remaining capacity based on the charge / discharge current of the device, the reference remaining capacity calculated by the first remaining capacity calculating means, and the remaining capacity one calculation cycle before The difference is regulated within the limiter limit set by the limiter setting means, and the remaining capacity change amount calculating means for calculating the remaining capacity change amount is calculated by the remaining capacity change amount calculating means for the remaining capacity before one calculation cycle. And a second remaining capacity calculating means for calculating the remaining capacity of the electricity storage device by adding the remaining capacity changes.

  At this time, the remaining capacity change amount is calculated as the remaining capacity change amount when the difference between the reference remaining capacity and the remaining capacity one calculation cycle before is less than the lower limit value of the limiter limit. When the difference is within the limit range, it is desirable to calculate the difference as the remaining capacity change amount, and when the difference exceeds the upper limit value of the limiter limit range, the upper limit value is preferably calculated as the remaining capacity change amount.

  In addition, it is desirable to calculate the change amount reference value serving as the reference value for the limit width of the limiter based on the ratio of the change amount of the charge / discharge current to the current capacity of the power storage device. It is desirable to calculate the upper limit value and the lower limit value of the limiter limit width by correcting with a correction coefficient calculated based on the current change rate and temperature of the discharge current.

  Furthermore, when the sensor for detecting the charge / discharge current of the electricity storage device is abnormal, it is desirable to set the limit range of the limiter with a preset fixed value, and the remaining capacity can be grasped with a predetermined accuracy even when an abnormality occurs. .

  The remaining capacity calculation device for an electricity storage device of the present invention avoids accumulation of errors due to current integration by calculating the remaining capacity mainly using an open-circuit voltage, and the influence of load fluctuations by a limiter set based on the charge / discharge current. Thus, it is possible to always obtain a uniform and highly accurate remaining capacity.

  Embodiments of the present invention will be described below with reference to the drawings. 1 to 10 relate to one embodiment of the present invention, FIG. 1 is a system configuration diagram showing an application example to a hybrid vehicle, FIG. 2 is a block diagram showing an estimation algorithm of a remaining battery capacity, and FIG. 3 is a battery capacity. FIG. 4 is an explanatory diagram showing the characteristics of the correction coefficient, FIG. 5 is a circuit diagram showing an equivalent circuit model, and FIG. 6 is an explanatory diagram showing the relationship between the reference remaining capacity and the open circuit voltage. 7 is a flowchart of the battery remaining capacity calculation process, FIG. 8 is an explanatory diagram of the impedance table, FIG. 9 is an explanatory diagram of the reference remaining capacity table, and FIG. 10 is an explanatory diagram showing the reference remaining capacity and the remaining capacity after noise removal processing. It is.

  FIG. 1 shows an example in which the present invention is applied to a hybrid vehicle (HEV) that travels using both an engine and a motor. In the figure, reference numeral 1 denotes a HEV power supply unit. The power supply unit 1 includes, for example, a battery 2 configured by connecting a plurality of battery packs in which a plurality of cells are sealed in series as power storage devices, calculation of the remaining capacity of the battery 2, cooling and charging of the battery 2, and the like. An arithmetic unit (arithmetic ECU) 3 that performs energy management such as control, abnormality detection, and protection operation at the time of abnormality detection is packaged in one casing.

  In this embodiment, a lithium ion secondary battery will be described as an example of an electricity storage device. However, the remaining capacity calculation method according to the present invention can also be applied to an electrochemical capacitor and other secondary batteries.

  The arithmetic ECU 3 is composed of a microcomputer or the like, and the terminal voltage V of the battery 2 measured by the voltage sensor 4, the charge / discharge current I of the battery 2 measured by the current sensor 5, and the temperature (cell) of the battery 2 measured by the temperature sensor 6. Based on (temperature) T, the state of charge (SOC), that is, the remaining capacity SOC (t) is calculated every predetermined time t.

  This remaining capacity SOC (t) is output from the arithmetic ECU 3 of the power supply unit 1 to the HEV control electronic control unit (HEV control ECU) 10 via, for example, CAN (Controller Area Network) communication or the like, for vehicle control. Used as basic data, battery remaining amount, display data for warning, and the like. The remaining capacity SOC (t) is also used as data (filter processing data described later) SOC (t−1) before one calculation cycle in the periodic calculation.

  The HEV control ECU 10 is similarly composed of a microcomputer or the like, and performs HEV operation and other necessary control based on a command from the driver. That is, the HEV control ECU 10 detects the state of the vehicle based on signals from the power supply unit 1 and signals from sensors and switches (not shown), and converts the DC power of the battery 2 into AC power to drive the motor 15. Starting with the inverter 20, an engine, an automatic transmission, etc. (not shown) are controlled via a dedicated control unit or directly.

  The calculation of the remaining capacity SOC in the calculation ECU 3 is executed according to the estimation algorithm shown in FIG. In this SOC estimation algorithm, the remaining capacity based on the estimated value of the open circuit voltage of the battery is mainly used, and noise removal processing is performed on this remaining capacity to obtain the final remaining capacity. That is, the remaining capacity based on the estimated value of the open-circuit voltage can be obtained accurately in the region where the current is stable, but the open-circuit voltage of the battery is estimated when the load fluctuates greatly in a short time. There is a possibility that the calculated impedance value cannot vibrate because the impedance at that time cannot be obtained accurately.

  Accordingly, in the present SOC estimation algorithm, parameters that can be measured by the battery 2, that is, the terminal voltage V, current I, and temperature T are used, and the estimated value of the open circuit voltage VOC of the battery is obtained by the function as the first remaining capacity calculating means. The remaining capacity (hereinafter, the remaining capacity based on the estimated value of the open circuit voltage VOC is referred to as “reference remaining capacity”) SOCV is calculated, and the noise removal processing is performed by the function as the limiter setting means and the remaining capacity change amount calculating means. Thus, the final remaining capacity SOC is calculated by the function as the second remaining capacity calculating means.

  As a result, the state of charge / discharge of the battery can be grasped more accurately, the reference remaining capacity SOCV based on the estimated value of the open circuit voltage is mainly used, the accumulation of errors due to current integration is eliminated, and the reference remaining capacity SOCV is promoted with a delay component. Thus, vibration due to load fluctuation can be suppressed, and an accurate remaining capacity can be obtained by taking advantage of the reference remaining capacity SOCV based on the estimated value of the open circuit voltage.

Specifically, the remaining capacity calculation process is executed using the remaining capacity SOC (t−1) one calculation cycle before by the discrete time process in the calculation ECU 3 (delay operator Z in the block diagram of FIG. 2). ^-1 ). That is, as shown in the following equation (1), the difference DSOCB between the reference remaining capacity SOCV (t) calculated in the current calculation cycle and the remaining capacity SOC (t−1) one calculation cycle before every predetermined time t. (= SOCV (t) −SOC (t−1)) is saturated within the limit using an upper / lower limiter set based on the battery current, and the saturated remaining capacity change amount DSOC is one calculation cycle before The final remaining capacity SOC (t) is calculated by adding to the remaining capacity SOC (t-1).
SOC (t) = SOC (t-1) + DSOC (1)

The upper / lower limiter is an upper limit value that determines the limiter width (limit width) by correcting the reference value with the ratio of the capacity change (Δt × I) in the calculation cycle Δt to the total battery capacity (current capacity) CBAH as a reference value. And set the lower limit. That is, according to the following equation (2), a change amount reference value DSOCI that serves as a reference value for the upper and lower limiters is calculated from the battery capacity CBAH, the battery current I, and the calculation cycle Δt, as shown in equations (3) and (4) Further, the upper limit value DSOCMAX and the lower limit value DSOCMIN are calculated by correcting the change amount reference value DSOCI with the correction coefficient KLMT.
DSOCI = | I × Δt / CBAH | (2)
DSOCMAX = KLMT × DSOCI (3)
DSOCMIN = −KLMT × DSOCI (4)

  As shown in FIG. 3, the battery capacity CBAH changes depending on the temperature T. Since the battery capacity decreases as the temperature becomes lower, for example, a table with the temperature T as a parameter is prepared. The battery capacity CBAH is calculated with reference to this table.

  When the difference DSOCB between the remaining capacity SOC (t−1) and the reference remaining capacity SOCV (t) before one calculation cycle is between the upper limit value DSOCMAX and the lower limit value DSOCMIN of the upper / lower limiter, the difference DSOCB is The remaining capacity change amount DSOC is used as it is. In this case, as apparent from the equation (1), the reference remaining capacity SOCV (t) becomes the final remaining capacity SOC (t).

  When the difference DSOCB is less than the lower limit value DSOCMIN, the lower limit value DSOCMIN is adopted as the remaining capacity change amount DSOC, and a value obtained by adding the lower limit value DSOCMIN to the remaining capacity SOC (t−1) one calculation cycle before is finally obtained. It is assumed that the remaining capacity SOC (t). Further, when the difference DSOCB exceeds the upper limit value DSOCMAX, the upper limit value DSOCMAX is adopted as the remaining capacity change amount DSOC, and a value obtained by adding the upper limit value DSOCMAX to the remaining capacity SOC (t-1) before one calculation cycle is obtained. The final remaining capacity SOC (t) is assumed.

  The correction coefficient KLMT is determined using the rate of change of current as a parameter reflecting the charge / discharge state of the battery. Although the current change rate directly reflects the load change of the battery, the mere current change rate is affected by a sudden change in current that occurs in a spike manner. The effects of this spike-like current can be mitigated by processing such as simple averaging, moving average, weighted averaging, etc. of a predetermined number of samplings, but especially when current delay is taken into account, changes in the charge / discharge state of the battery On the other hand, the correction coefficient KLMT is determined using a moving average that can appropriately reflect the past history without becoming excessive.

  Specifically, since the rate of change of the battery current is affected by the temperature T, the correction coefficient KLMT is defined as the moving average value of the battery current I per unit time, that is, the moving average value of the battery current I is IM. The moving average value IM is calculated on the basis of the current change rate ΔIM / Δt at time t and the battery temperature T, and is stored in a table or the like created through experiments or simulations in advance.

  FIG. 4 shows the characteristics of the correction coefficient KLMT that changes depending on the current change rate ΔIM / Δt by the moving average and the battery temperature T. The lower the temperature, the higher the internal impedance of the battery and the open circuit voltage. Therefore, the value of the correction coefficient KLMT is set small, and the value of the correction coefficient KLMT is increased as ΔIM / Δt decreases.

  That is, in a state where the load fluctuation of the battery is small and stable (a state where ΔIM / Δt is small and the current change is small), the correction coefficient KLMT is set to a large value so as to widen the limiter width by the upper limit value DSOCMAX and the lower limit value DSOCMIN. It is possible to reduce the response delay as much as possible by increasing the chance of adopting the latest reference remaining capacity SOCV (t) as the final remaining capacity SOC (t) by removing only sudden fluctuations.

  Conversely, in a state where the load fluctuation is large (a state where ΔIM / Δt is large and the current change is large), the correction coefficient KLMT is set to a small value so as to narrow the limiter width and is expected to contain a lot of noise components. By adopting the upper limit value DSOCMAX or the lower limit value DSOCMIN of the upper / lower limiter based on the battery current instead of the reference remaining capacity SOCV (t) of the current calculation cycle, the noise component is removed without promoting the delay component Variation can be suppressed.

  Further, since the final remaining capacity SOC is calculated mainly based on the reference remaining capacity SOCV based on the open circuit voltage VOC without performing current integration, there is a case where the current sensor 5 that detects the battery current fails. It is possible to calculate the remaining capacity SOC with a certain degree of accuracy. That is, when the current sensor is abnormal, the upper limit value DSOCMAX and the lower limit value DSOCMIN of the upper / lower limiter are respectively replaced with the preset set value FILMT to fix the limiter width, thereby ensuring a predetermined accuracy. It is possible to smoothly shift to fail-safe control.

  Further, as a feature of the present SOC estimation algorithm, the internal state of the battery is electrochemically grasped based on the battery theory, and the calculation accuracy of the reference remaining capacity SOCV based on the battery open voltage VOC is improved. Hereinafter, the calculation of the reference remaining capacity SOCV by this estimation algorithm will be described in detail.

  In order to obtain the reference remaining capacity SOCV, first, the internal impedance Z of the battery is obtained using the equivalent circuit model shown in FIG. This equivalent circuit is an equivalent circuit model in which parameters of resistance components R1 to R3 and capacitance components C1, CPE1, and CPE2 (where CPE1 and CPE2 are double layer capacitance components) are combined in series and in parallel. Each parameter is determined by curve fitting a well-known Cole-Cole plot in the method.

The impedance Z obtained from these parameters varies greatly depending on the temperature of the battery, the electrochemical reaction rate, and the frequency component of the charge / discharge current. Therefore, as the parameter for determining the impedance Z, the current change rate ΔIM / Δt based on the moving average described above is adopted as the replacement of the frequency component, and impedance measurement is performed with the current change rate ΔIM / Δt and the temperature T as conditions. Is stored, an impedance Z table (an impedance table in FIG. 8 described later) is created based on the temperature T and the current change rate ΔIM / Δt. Then, the impedance Z is obtained using this table, and the estimated value of the open circuit voltage VOC is obtained from the impedance Z, the measured terminal voltage V, and the current I using the following equation (5).
VOC = V + I · Z (5)

  More specifically, since the internal impedance of the battery increases and the current change rate decreases as the temperature decreases, the impedance Z directly corrects the current change rate ΔIM / Δt as described later. It is determined using the corrected current change rate KΔIM / Δt.

After the open circuit voltage VOC is estimated, the reference remaining capacity SOCV is calculated based on the electrochemical relationship in the battery. Specifically, a well-known Nernst equation describing the relationship between the electrode potential and the ion activity in the equilibrium state is applied, and the relationship between the open circuit voltage VOC and the reference remaining capacity SOCV is expressed as (6 ) Formula can be obtained.
VOC = E + [(Rg · T / Ne · F) × lnSOCV / (100−SOCV)] + Y (6)
However, E: Standard electrode potential (E = 3.745 in the lithium ion battery of this embodiment)
Rg: Gas constant (8.314 J / mol-K)
T: temperature (absolute temperature K)
Ne: Ion valence (Ne = 1 in the lithium ion battery of this embodiment)
F: Faraday constant (96485 C / mol)

Note that Y in the equation (6) is a correction term and expresses the voltage-SOC characteristic at normal temperature as a function of SOC. If SOCV = X, it can be expressed by a cubic function of SOC as shown in the following equation (7).
Y = −10 ⁻⁶ X ³ + 9 · 10 ⁻⁵ X ² + 0.013X−0.7311 (7)

  The specific correlation between the open circuit voltage VOC expressed by the above equation (6) and the reference remaining capacity SOCV varies depending on the type and characteristics of the battery. For example, in a lithium ion battery, the curve is as shown in FIG. Can be represented. The relationship between the open circuit voltage VOC and the reference remaining capacity SOCV shown in FIG. 6 is a correlation represented by a curve that changes monotonously without a change in the reference remaining capacity SOCV being flat with respect to a change in the open circuit voltage VOC. By knowing the value of the open circuit voltage VOC, the value of the reference remaining capacity SOCV can be clearly grasped.

  Further, it can be seen that the reference remaining capacity SOCV has a strong correlation not only with the open circuit voltage VOC but also with the battery temperature T, and even if the open circuit voltage VOC has the same value as shown in FIG. When the temperature T decreases, the reference remaining capacity SOCV decreases. In this case, it is possible to directly calculate the reference remaining capacity SOCV by using the equation (6) using the open-circuit voltage VOC and the temperature T as parameters, but in actuality, the charge / discharge characteristics and usage specific to the battery to be used are used. Consideration of conditions is necessary.

  Therefore, when grasping the actual state of the battery from the relationship of the above equation (6), a charge / discharge test or simulation in each temperature range is performed on the basis of the SOC-Vo characteristic at room temperature, and the measured data is obtained. accumulate. Then, a table of reference remaining capacity SOCV (reference remaining capacity table of FIG. 9 described later) that parameters open circuit voltage VOC and temperature T is created from the accumulated measured data, and the reference remaining capacity SOCV is used using this table. Ask for. After obtaining the reference remaining capacity SOCV, a noise removal process mainly using the above-described equation (1) is performed to calculate the final remaining capacity SOC.

  Next, the calculation process of the battery remaining capacity SOC by the above noise removal process will be described with reference to the flowchart of FIG.

  The flowchart of FIG. 7 shows a basic process of remaining capacity estimation in the arithmetic ECU 3 of the power supply unit 1, and is executed at predetermined time intervals (for example, every 0.1 sec). When this process starts, first, in step S1, the terminal voltage V, current I, temperature T of the battery 2 and data of the remaining capacity SOC (t−1) calculated during the previous calculation process are read. The terminal voltage V is the average value of the plurality of battery packs, and the current I is the sum of the currents of the plurality of battery packs. For example, data is acquired every 0.1 sec. The temperature T is acquired every 10 seconds, for example.

  Next, the process proceeds to step S2 to obtain a current change rate ΔIM / Δt per unit time by averaging the current I. For example, when the current I is sampled every 0.1 sec and the current integration calculation cycle is every 0.5 sec, the moving average of the current I is a moving average of five data. Further, in step S3, the impedance Z of the battery equivalent circuit is calculated with reference to the impedance table shown in FIG. The impedance table of FIG. 8 shows the impedance Z of the equivalent circuit with the corrected current change rate KΔIM / Δt obtained by correcting the temperature of the current change rate ΔIM / Δt (moving average value of the current I per unit time) and the temperature T as parameters. In general, when the corrected current change rate KΔIM / Δt is the same, the impedance Z increases as the temperature T becomes lower. At the same temperature, the corrected current change rate KΔIM / As Δt decreases, the impedance Z tends to increase.

  In step S4 subsequent to step S3, the open-circuit voltage VOC of the battery 2 is calculated according to the above-described equation (5) using the calculated impedance Z. In step S5, the reference remaining capacity SOCV is calculated by referring to the reference remaining capacity table shown in FIG. 9 using the temperature T and the open circuit voltage VOC as parameters. As described above, the reference remaining capacity table is a table created by grasping the electrochemical state in the battery based on the Nernst equation. In general, the temperature T and the open circuit voltage VOC are lowered. As the reference remaining capacity SOCV decreases, the reference remaining capacity SOCV tends to increase as the temperature T and the open circuit voltage VOC increase.

  In FIGS. 8 and 9, data in a range used under normal conditions is shown, and data in other ranges is omitted.

  Thereafter, the process proceeds to step S6, where the battery capacity CBAH is obtained by referring to the table or the like using the battery temperature T as a parameter. DSOCI is calculated. Further, in step S7, based on the current change rate ΔIM / Δt and the battery temperature T, a correction coefficient KLMT is calculated by referring to a table or the like. As described above, the correction coefficient KLMT is generally reduced by reducing the limiter width with respect to the change amount of the remaining capacity as the current change rate ΔIM / Δt increases, that is, as the battery load fluctuation increases. Set to effectively remove.

  After calculating the correction coefficient KLMT, the process proceeds to step S8 to determine whether or not the current sensor 5 has failed. The failure determination for the current sensor 5 is determined to be a failure when, for example, the detection value by the current sensor 5 indicates a value that cannot normally be taken. As a result, when the current sensor 5 is normal, the process proceeds from step S8 to step S9, and the upper limit value DSOCMAX and the change value reference value DSOCI and the correction coefficient KLMT are calculated according to the above-described equations (3) and (4). The lower limit value DSOCMIN is calculated, and the process proceeds to step S11. If the current sensor 5 has failed, the process proceeds from step S8 to step S10, and the upper limit value DSOCMAX and the lower limit value DSOCMIN are fixed to the set values FILMT and -FILMT, respectively (DSOCMAX = FILMT, DSOCMIN = -FILMT), go to step S11.

  In step S11, the difference DSOCB is calculated by subtracting the remaining capacity SOC (t-1) of the previous calculation cycle from the reference remaining capacity SOCV (t) in the current calculation cycle calculated in step S5. In step S12, the difference DSOCB is calculated. It is checked whether DSOCB is less than the lower limit DSOCMIN. If DSOCB <DSOCMIN, the process proceeds from step S12 to step S16, the lower limit DSOCMIN is set as the remaining capacity change amount DSOC (DSOC = DSOCMIN), and the process proceeds to step S17.

  On the other hand, if DSOCB ≧ DSOCMIN, the process proceeds from step S12 to step S13 to check whether the difference DSOCB is equal to or lower than the upper limit value DSOCMAX. If DSOCB> DSOCMAX, the upper limit value DSOCMAX is set as the remaining capacity change amount DSOC in step S14 (DSOC = DSOCMAX), and in step S17, the remaining capacity SOC (one calculation cycle before the calculation cycle according to the above-described equation (1) ( The remaining capacity change amount DSOC is added to t-1) to calculate a new remaining capacity SOC (t), and one cycle of this process is completed.

  If DSOCB ≦ DSOCMAX, the difference DSOCB is set as the remaining capacity change amount DSOC in step S15 (DSOC = DSOCB), and in step S17, the remaining capacity SOC (one calculation cycle before the calculation cycle (1) is calculated according to the above equation (1). The remaining capacity change amount DSOC is added to t-1) to calculate a new remaining capacity SOC (t), and one cycle of this process is completed. In this case, the reference remaining capacity SOCV (t) in the current calculation cycle calculated in step S5 becomes the new remaining capacity SOC (t).

  FIG. 10 shows the reference remaining capacity SOCV and the remaining capacity SOC after the noise removal process, and it can be seen that the vibrational noise component of the reference remaining capacity SOCV based on the open circuit voltage VOC is effectively removed. In addition, noise components are removed without using a “smoothing” process such as a filter, so that there is no delay in a stable state with little fluctuation in battery current, and the remaining capacity is accurate and with good followability. Can be grasped.

System configuration diagram showing an example of application to a hybrid vehicle Block diagram showing the remaining battery capacity estimation algorithm Explanatory diagram showing the relationship between battery capacity and temperature An explanatory view showing the characteristics of the correction coefficient, Circuit diagram showing equivalent circuit model Explanatory diagram showing the relationship between reference remaining capacity and open circuit voltage Flow chart of remaining battery capacity calculation processing Illustration of impedance table Illustration of the standard remaining capacity table Explanatory diagram showing the reference remaining capacity and the remaining capacity after noise removal processing

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Power supply unit 2 Battery 3 Arithmetic unit (1st remaining capacity calculation means, limiter setting means, remaining capacity change amount calculation means, 2nd remaining capacity calculation means)
I Charge / discharge current SOCV Reference remaining capacity SOC Remaining capacity VOC Open circuit voltage DSOCB Difference DSOC Residual capacity change amount DSOCMAX Upper limit value DSOCMIN Lower limit value DSOCI Change amount reference value KLMT Correction coefficient
Agent Patent Attorney Susumu Ito

Claims (5)

First remaining capacity calculating means for calculating a remaining capacity based on an estimated value of an open circuit voltage of the electricity storage device as a reference remaining capacity;
Limiter setting means for setting a limiter for limiting the amount of change in the remaining capacity based on the charge / discharge current of the power storage device,
The difference between the reference remaining capacity calculated by the first remaining capacity calculating means and the remaining capacity one calculation cycle before is restricted within the limiter limit set by the limiter setting means, and the remaining capacity calculated as the remaining capacity change amount Capacity change amount calculating means;
And a second remaining capacity calculating means for calculating the remaining capacity of the power storage device by adding the remaining capacity change calculated by the remaining capacity change calculating means to the remaining capacity before one calculation cycle. Device for calculating remaining capacity of a storage device. The remaining capacity change amount calculating means is:
When the difference is less than the lower limit value of the limiter limit, the lower limit value is calculated as the remaining capacity change amount. When the difference is within the limiter limit range, the difference is calculated as the remaining capacity change amount. The remaining capacity calculation device for an electricity storage device according to claim 1, wherein when the difference exceeds an upper limit value of the limit width of the limiter, the upper limit value is calculated as the remaining capacity change amount. The limiter setting means is
3. The power storage device according to claim 1, wherein a change amount reference value that is a reference value of a limit width of the limiter is calculated based on a ratio of a change amount of the charge / discharge current to a current capacity of the power storage device. Remaining capacity calculation device. The limiter setting means is
The change reference value is corrected by a correction coefficient calculated based on the current change rate and temperature of the charge / discharge current of the power storage device, and an upper limit value and a lower limit value of the limit width of the limiter are calculated. The remaining capacity computing device for an electricity storage device according to claim 3. The limiter setting means is
3. The remaining capacity computing device for an electrical storage device according to claim 1, wherein when the sensor that detects the charge / discharge current of the electrical storage device is abnormal, the limit width of the limiter is set with a preset fixed value.

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