JP6494923B2 - Charging rate detection apparatus and charging rate detection method - Google Patents

Description

  The present invention relates to a charging rate detection device and a charging rate detection method capable of accurately detecting a charging rate (SOC: State of Charge) of a battery in use, particularly a lead storage battery.

  A vehicle such as an automobile is often equipped with a rechargeable battery (secondary battery, hereinafter simply referred to as “battery”). Such a battery stores (charges) electrical energy obtained by converting mechanical kinetic energy transmitted from an engine or the like with an alternator, and supplies (discharges) electrical energy to a motor for driving the vehicle. . In order for the driver of the vehicle to accurately grasp the travelable distance and the like, it is necessary to accurately calculate the charging rate, which is the internal state quantity of the battery, even while the vehicle is traveling.

  As a method for calculating the charging rate of a battery in use, there is a method for obtaining by accumulating current. However, in a lead storage battery that is often mounted on a vehicle, not all of the charged charge can be taken out as it is. Therefore, when calculating the charging rate of a battery such as a lead storage battery, it is necessary to consider the charging efficiency (ratio between the amount of discharge and the amount of charge).

  For example, in the invention of Patent Document 1, charging and discharging are performed at the time of replacement of a lead storage battery, and a charging efficiency is obtained by dividing a discharge current integrated value until returning to the original voltage by a charging current integrated value. Therefore, it is possible to individually grasp the charging efficiency of lead-acid batteries having individual differences at the start of use.

JP 2006-36003 A

  However, the invention of Patent Document 1 continues to use the charging efficiency obtained at the time of replacement of the lead storage battery for the battery, and cannot cope with the change in charging efficiency over time. Moreover, the charge and discharge intentionally performed at the time of replacement of the lead storage battery use electric power wastefully, and if it is excessively discharged at that time, there is a possibility that the deterioration of the lead storage battery is promoted.

  In recent years, the battery is often used in an incompletely charged state rather than a fully charged state in order to always leave a surplus charge. In the invention of Patent Document 1, full charge determination is incorporated in the processing flow, and only a system based on full charge can be handled.

  The object of the present invention, which has been made in view of the above problems, can cope with changes in charging efficiency over time, and accurately calculates the charging rate of a battery in use even when used in an incompletely charged state. An object of the present invention is to provide a charge rate detection device and a charge rate detection method that can be used.

In order to solve the above-described problem, a charging rate detection device according to a first aspect of the present invention is configured to integrate a charging current of a battery in operation and generate a charging current integrated value, and a discharging current of the battery. When the discharge current integration unit that integrates and generates the discharge current integration value and at least one of the conditions (a) or (b) is satisfied, the magnitude of the discharge current integration value is the magnitude of the charge current integration value. A charging efficiency calculation unit that calculates a charging efficiency obtained by dividing by the above, and the condition (a) is an open circuit estimated at the start of integration after the estimated open circuit voltage of the battery fluctuates. The condition (b) is such that the absolute value of the discharge current integrated value and the absolute value of the charge current integrated value are large enough to ensure the accuracy of the division. It is characterized by that.

  Further, a charging rate detection device according to a second aspect of the present invention is the charging rate detection device according to the first aspect of the invention, further comprising an open-circuit voltage estimation unit that estimates an open-circuit voltage from the detected current and voltage of the battery. The first charging rate is calculated based on the open circuit voltage estimated by the estimation unit.

  The charging rate detection device according to a third aspect of the present invention is the charging rate detection device according to the second aspect of the present invention, based on the change amount of the charge current integrated value, the change amount of the discharge current integrated value, and the charge efficiency. The first charging rate is calculated based on the open circuit voltage that has passed through the filter, including a filter unit that includes a filter that adjusts the amount of change in the open circuit voltage estimated by the open circuit voltage estimation unit.

  The charging rate detection device according to a fourth aspect of the invention is the charging rate detection device of the second or third aspect, wherein the charging current calculation value is calculated when the charging efficiency calculation unit calculates the charging efficiency, The second charging rate calculated based on the discharge current integrated value and the charging efficiency or the first charging rate is selectively output.

  According to a fifth aspect of the present invention, there is provided a charge rate detecting device according to any one of the first to fourth aspects, wherein the battery is mounted on a vehicle, and the charge current integrating unit The discharge current integrating unit continuously integrates the charging current and the discharging current in a plurality of operations of the vehicle.

  According to a sixth aspect of the present invention, there is provided a charge rate detecting device according to any one of the first to fifth aspects, wherein the battery state is controlled so that the open circuit voltage of the battery is constant. Includes a control unit.

  Further, a charging rate detection device according to a seventh aspect of the present invention is the charging rate detection device according to any one of the first to sixth aspects, wherein the charging efficiency calculation unit includes the conditions (a) and (b ), The charging efficiency is calculated.

According to an eighth aspect of the present invention, there is provided a charging rate detection method comprising: (A) accumulating charging current of an operating battery to generate a charging current integrated value; and (B) accumulating discharging current of the battery. When the discharge current integrated value is generated and (C) at least one of the conditions (a) and (b) is satisfied, the discharge current integrated value is divided by the charge current integrated value. And calculating the charging efficiency obtained in the above, wherein the condition (a) is a predetermined range from the open voltage estimated at the start of integration after the estimated open voltage of the battery has changed. The condition (b) is that the absolute value of the discharge current integrated value and the absolute value of the charge current integrated value are of a size that ensures the accuracy of the division. Features.

  According to the charging rate detection device of the first aspect of the invention, the charging efficiency of the battery in use can be obtained by calculation, so that the charging rate can be accurately calculated based on this charging efficiency. . Here, in the invention of Patent Document 1 that continues to use the calculated charging efficiency for the replaced battery, the charging efficiency of each section is obtained by performing a calculation based on the fully charged state when the battery is replaced. There was a need. However, in the present invention in which the charging efficiency can be calculated while the battery is in use, the calculation based on the fully charged state is not necessary. Therefore, even when a battery is used in an incompletely charged state, it can respond.

  Further, according to the charging rate detection device of the second invention, an open circuit voltage (OCV) that does not need to consider an error due to the voltage drop of the internal resistance is obtained. A high charge rate (first charge rate) can be calculated.

  According to the charging rate detection device of the third aspect of the invention, the charging rate (first charging) is corrected by correcting the amount of change in the open-circuit voltage estimated using the amount of change in the integrated charge / discharge current value. Rate) can be further improved.

  Moreover, according to the charging rate detection apparatus which concerns on 4th invention, the 2nd charging rate based on charging / discharging electric current integrated value and the 1st charging rate based on the estimated open circuit voltage are according to a condition. It is possible to selectively output, and it is possible to maintain the accuracy of the charging rate that is finally output.

  Moreover, according to the charging rate detection apparatus which concerns on 5th invention, the battery is mounted in the vehicle. And even if it is only a short distance driving | running | working with one operation | movement of a vehicle, since cumulative integration | stacking can be performed about the repeated short distance driving | running, charging efficiency with few errors is obtained.

  Further, according to the charging rate detection device of the sixth aspect of the invention, when the charging rate changes greatly, there is a possibility that the error in charging efficiency may become large, so that the open circuit voltage of the battery is controlled to be constant. This can reduce the error.

  Moreover, according to the charging rate detection apparatus which concerns on 7th invention, since charging efficiency is calculated when the conditions (a) and (b) are satisfy | filled, it becomes further exact.

  In addition, according to the charging rate detection method of the eighth aspect of the invention, since the charging efficiency of the battery in use is obtained by calculation, the charging efficiency can be changed over time, and the charging rate can be accurately determined based on the charging efficiency. It can be calculated. Here, in the invention of Patent Document 1 that continues to use the calculated charging efficiency for the replaced battery, the charging efficiency of each section is obtained by performing a calculation based on the fully charged state when the battery is replaced. There was a need. However, in the present invention in which the charging efficiency can be calculated while the battery is in use, the calculation based on the fully charged state is not necessary. Therefore, even when a battery is used in an incompletely charged state, it can respond.

It is a block diagram which shows the charging rate detection apparatus which concerns on this embodiment. It is a figure which illustrates the equivalent circuit of the battery used with an open circuit voltage estimation part. FIGS. 3A and 3B are diagrams showing changes in the estimated open circuit voltage before and after passing through the filter, respectively. It is a figure which shows the open circuit voltage-charging rate characteristic of a battery. It is a figure which shows the relationship between the residual amount detected and the charging efficiency in the case of controlling the residual amount of a battery uniformly. It is a figure which illustrates the change of the estimated open circuit voltage of a battery. It is a flowchart which shows the process of the charging rate detection apparatus which concerns on this embodiment.

Embodiments of the present invention will be described below.
(overall structure)
First, the overall configuration of the charging rate detection apparatus 10 of the present embodiment will be described with reference to FIG. The charging rate detection device 10 is connected to a battery B mounted on a vehicle such as an automobile. Although the kind of battery B is not specifically limited, it demonstrates below that it is a lead acid battery. The battery B accumulates (charges) electrical energy obtained by converting mechanical kinetic energy with the alternator Alt, and supplies (discharges) electrical energy to a drive motor or the like of a vehicle (not shown). The battery B of the present embodiment receives and charges regenerative power generated when the vehicle decelerates from the alternator Alt. The charging rate detection apparatus 10 calculates the charging rate of the battery B that is charged and discharged during operation of the vehicle. Moreover, the charging rate detection apparatus 10 of this embodiment can also control the state of the battery B by giving a control signal to the alternator Alt. Here, the operation of the vehicle means a state in which the engine of the vehicle is running and is running or stopped for movement.

  The charging rate detection device 10 includes an open-circuit voltage estimation unit 12, an SOCv calculation unit 14, a current integration unit 16, an SOCi calculation unit 18, an SOC selection unit 20, and a battery state control unit 22. As an outline, the charging rate detection device 10 receives the terminal voltage VB and the current IB of the battery B during operation of the vehicle, that is, during use of the battery B, and charges the battery B in real time when a predetermined condition is satisfied. The efficiency η is obtained by calculation. Therefore, the charging efficiency η corresponding to the change with time of the battery B can be obtained, and the highly accurate charge rate SOC can be calculated based on the charging efficiency η reflecting the change with time. The terminal voltage VB of the battery B is detected by a voltage sensor (not shown) and output to the charging rate detection device 10. Further, the current IB of the battery B is detected by a current sensor (not shown) and output to the charging rate detection device 10.

  The open circuit voltage estimation unit 12 receives the terminal voltage VB and the current IB of the battery B, and outputs the first estimated open circuit voltage OCVe. The first estimated open circuit voltage OCVe is obtained by applying a current IB to an equivalent circuit (hereinafter referred to as “battery model”) of the battery B included in the open circuit voltage estimation unit 12. A configuration example of the battery model will be described later. The charging rate detection device 10 includes the open-circuit voltage estimation unit 12, so that the open-circuit voltage charging rate SOCv can be calculated with high accuracy based on the open-circuit voltage that does not need to consider the error of the voltage drop of the internal resistance of the battery B. Is possible.

  The SOCv calculation unit 14 receives the first estimated open circuit voltage OCVe and outputs the open circuit voltage charging rate SOCv. The open-circuit voltage charging rate SOCv corresponds to the first charging rate of the present invention. The SOCv calculation unit 14 includes a filter unit 24 and an OCV-SOC conversion unit 26. The filter unit 24 receives the first estimated open circuit voltage OCVe and executes a filter process. The filter unit 24 also receives a current (correction value Sd) corresponding to the amount of change in the current integration value Sa obtained by the current integration method from the current integration unit 16. Then, the correction value Sd is used to perform a filtering process for limiting the amount of change in the first estimated open circuit voltage OCVe (hereinafter also referred to as “rate limit”), and the second error is smaller than the first estimated open circuit voltage OCVe. The estimated open circuit voltage OCVv is output. Examples of waveforms of the first estimated open circuit voltage OCVe and the second estimated open circuit voltage OCVv will be described later. In the present embodiment, the second estimated open circuit voltage OCVv corresponds to the “estimated open circuit voltage” of the present invention. However, as another embodiment, the first estimated open circuit voltage OCVe is used as the “estimated open circuit voltage” of the present invention. It may be “voltage”.

  The OCV-SOC conversion unit 26 receives the second estimated open circuit voltage OCVv, performs conversion from the open circuit voltage to the charge rate (hereinafter referred to as “OCV-SOC conversion”), and outputs the open circuit voltage charge rate SOCv. To do. It is known that the relationship between the open circuit voltage and the charging rate is kept constant regardless of temperature and deterioration. Therefore, the OCV-SOC conversion unit 26 may store an OCV-SOC conversion table based on the open-circuit voltage-charge rate characteristics of the battery B, which is obtained in advance through experiments or the like. An example of the open-circuit voltage-charge rate characteristic will be described later.

  The current integration unit 16 receives the current IB of the battery B and outputs a current integration value Sa and a correction value Sd. The current integrated value Sa is an integrated value of the current IB of the battery B obtained by the current integrating method, and the correction value Sd is a current corresponding to the change amount of the current integrated value Sa.

The current integrating unit 16 includes a charging current integrating unit 33, a discharge current integrating unit 32, and a charging efficiency calculating unit 35. The charging current integrating unit 33 integrates the charging current I _in of the battery B to generate a charging current integrated value ∫ (I _in ) dt. The discharge current integrating unit 32 integrates the discharge current I _out of the battery B to generate a discharge current integrated value ∫ (I _out ) dt. The charging efficiency calculation unit 35 calculates the charging efficiency η obtained by dividing the magnitude (absolute value) of the discharge current integrated value ∫ (I _out ) dt by the magnitude of the charge current integrated value ∫ (I _in ) dt. To do.

Further, in the charging rate detection device 10 of the present embodiment, the current integration unit 16 includes a separation conversion unit 31, a multiplier, and an adder. The separation conversion unit 31 receives the current IB of the battery B, separates it into a charging current _Iin and a discharging current _Iout, and outputs it as a signed value so that efficient calculation can be performed in a subsequent circuit. The multiplier and the adder are used in the calculation for obtaining the current integrated value Sa and the correction value Sd. Formulas for calculating the current integrated value Sa and the correction value Sd will be described later.

  The SOCi calculation unit 18 receives the current integrated value Sa, adds an initial value at the start of integration (hereinafter referred to as “initial charge rate”), and outputs a current integrated charge rate SOCi. The current integrated charging rate SOCi corresponds to the second charging rate of the present invention. The SOCi calculation unit 18 includes a storage unit 38. The storage unit 38 is a non-volatile memory, for example, and stores an initial charging rate. Further, the storage unit 38 may store the current integrated charging rate SOCi (hereinafter referred to as “past current integrated charging rate SOCi”) previously output by the SOCi calculating unit 18. Then, the SOCi calculation unit 18 outputs the past current integration charge rate SOCi read from the storage unit 38 when the accuracy of the current integration charge rate SOCi obtained by calculation based on the current integration value Sa is low. Can do.

  The SOC selection unit 20 selects the open circuit voltage charging rate SOCv or the current integrated charging rate SOCi according to the selection signal Sel, and outputs it as the charging rate SOC. The selection signal Sel is output from a selection control unit (not shown), and the selection control unit compares, for example, the open-circuit voltage charging rate SOCv and the current integrated charging rate SOCi and selects the one that seems to have higher accuracy. The signal Sel may be output. Further, the selection control unit may output the selection signal Sel so as to make a selection linked to the operation of the vehicle (for example, output the current integrated charging rate SOCi when the vehicle is stopped). In the present embodiment, as will be described later, in principle, the current integrated charging rate SOCi is selected as the charging rate SOC, but when the data in the charging current integrating unit 33, the discharge current integrating unit 32, and the storage unit 38 are reset. The open-circuit voltage charging rate SOCv is selected. By including the SOC selection unit 20, the charging rate detection device 10 can selectively output the open-circuit voltage charging rate SOCv and the current integrated charging rate SOCi according to the situation, and the accuracy of the finally output charging rate SOC Can be kept.

  The battery state control unit 22 controls the battery B to be the target open circuit voltage by giving a control signal to the alternator Alt based on the second estimated open circuit voltage OCVv. By including the battery state control unit 22, the charging rate detection device 10 can control the open voltage of the battery B to be constant. When the charging rate of the battery B changes greatly during the current integration, there is a possibility that the error of the charging efficiency η may increase. Therefore, the battery state control unit 22 performs control so that the open voltage of the battery B is constant. If this is done, the error in charging efficiency η can be kept small. Further, since the charging efficiency calculation unit 35 does not obtain the charging efficiency η based on the full charge, there is no need to fully charge the battery B. Therefore, the charging rate detection device 10 including the battery state control unit 22 is preferably used in a system that uses the battery B in an incompletely charged state.

  The overall configuration of the charging rate detection device 10 has been described above with reference to FIG. 1, but the details of the open-circuit voltage estimation unit 12, the SOCv calculation unit 14, and the current integration unit 16 will be described below, and then the charging rate detection is performed. Processing of the device 10 will be described.

(Open voltage estimation part)
FIG. 2 is an equivalent circuit (battery model) of the battery B. The battery model includes a resistance R0 that sets a direct current component such as an electrolyte resistance and an ohmic resistance, a resistance R1 that is set as a reaction resistance that represents a dynamic behavior in a charge transfer process, C1 that is set as an electric double layer, diffusion R2 and C2 set to represent dynamic behavior in the process. Here, although the equivalent circuit model of the primary parallel circuit in the charge transfer process and the secondary parallel circuit in the diffusion process is represented, the order is set as necessary.

  When the current IB is input to the battery model, each parameter R0, R1, R2, C1, and so on of the battery model is set by an adaptive mechanism (not shown) so that there is no difference between the terminal voltage VB of the battery B and the terminal voltage estimated value VBm of the battery model. By sequentially correcting C2, a battery model that matches the current state of the battery B can be obtained.

  The open-circuit voltage estimation unit 12 calculates the overvoltage VR from the estimated parameters R0, R1, R2, C1, and C2 and the current IB, and calculates the open-circuit voltage OCV by subtracting the overvoltage VR from the terminal voltage VB. The calculated open circuit voltage OCV corresponds to the first estimated open circuit voltage OCVe of FIG.

  Here, the adaptive mechanism for sequentially correcting the parameters R0, R1, R2, C1, and C2 may be, for example, a Kalman filter. The Kalman filter is a filter suitable for self-correcting internal parameters, and is used for sequential parameter estimation. Details of parameter estimation by the Kalman filter are described in Japanese Patent Application No. 2011-007874 of the present applicant.

(SOCv calculation unit)
The SOCv calculation unit 14 includes the filter unit 24 and the OCV-SOC conversion unit 26 as described above. FIG. 3A and FIG. 3B are diagrams showing changes in the estimated open circuit voltage before and after passing through the filter unit 24, respectively. FIG. 3A shows an example of the time change of the first estimated open circuit voltage OCVe. Filter processing for performing rate limiting is performed on the first estimated open circuit voltage OCVe by the filter unit 24. Therefore, the time change of the second estimated open circuit voltage OCVv shown in FIG. 3B is more gradual than the first estimated open circuit voltage OCVe. In this example, the second estimated open circuit voltage OCVv varies around Vtg. Here, Vtg is the value of the second estimated open circuit voltage OCVv obtained at the start of integration. The integration start time is when the charging current integration unit 33 and the discharge current integration unit 32 start integration. As will be described later, the accumulation is performed through a plurality of vehicle operations (for example, “from the start of running the engine to the destination and turning off the engine” can be considered as a single operation). It is preferred that In such a case, the start time of the first vehicle operation is the start of integration. In the examples of FIGS. 3A and 3B, Vtg may be obtained before the origin of the time axis. Further, Vtg may be a value equal to the open circuit voltage targeted by the battery state control unit 22.

  The filter unit 24, for example, a variance based on the correction value Sd received from the current integrating unit 16 (current integrating method variance) and a variance based on the first estimated open-circuit voltage OCVe received from the open-circuit voltage estimating unit 12 (open-circuit voltage estimating method). The second estimated open circuit voltage OCVv may be generated by calculating the (dispersion) and performing a rate limit based on the relationship of these dispersions. Here, with respect to generation of the second estimated open circuit voltage OCVv, a method of correcting the error model so that the error is minimized by the Kalman filter may be employed. At this time, the filter unit 24 uses a so-called sensor fusion technique in which an estimation error is corrected using a value based on the current integration method and a value based on the open-circuit voltage estimation method. As described above, details of parameter estimation by the Kalman filter are described in Japanese Patent Application No. 2011-007874 of the present applicant.

  FIG. 4 is a diagram illustrating an open-circuit voltage-charge rate characteristic of the battery B. In the characteristic of FIG. 4, when the open circuit voltage OCV is V0 [V], the charging rate SOC is 0 [%]. Further, when the open circuit voltage OCV is V1 [V], the charging rate SOC is 100 [%]. A specific example of the battery B, which is a lead storage battery, shows, for example, V0 of about 1.9 [V] and V1 of about 2.1 [V]. The OCV-SOC conversion unit 26 stores a relational expression between the open circuit voltage and the charging rate (for example, a primary relational expression in the case of a lead storage battery), and the value of the charging rate SOC according to the received value of the second estimated open circuit voltage OCVv. Is output as the open circuit voltage charge rate SOCv.

(Current integration part)
Here, referring to FIG. 1 again, the calculation in the current integrating unit 16 will be described. Separating converter 31, a current IB of the received battery B, divided into the charging current I _in and the discharge current I _out. Here, the charging current I _in and the discharging current I _out are given opposite signs, and the following description will be made assuming that the charging current I _in takes a positive value and the discharging current I _out takes a negative value.

Then, the charging current integrating unit 33 integrates the charging current I _in from the start of integration to generate a charging current integrated value ∫ (I _in ) dt. The discharge current integrating unit 32 integrates the discharge current I _out from the start of integration to generate a discharge current integrated value ∫ (I _out ) dt.

The charging efficiency calculation unit 35 calculates the charging efficiency η, and is obtained by dividing the magnitude of the discharge current integrated value ∫ (I _out ) dt by the size of the charging current integrated value ∫ (I _in ) dt. That is,
η = | ∫ (I _out ) dt | / ∫ (I _in ) dt (Formula 1)
It becomes.

The current integrating unit 16 outputs a current integrated value Sa and a correction value Sd that is a current corresponding to the amount of change in the current integrated value Sa. Here, the current integrated value Sa is given by the following equation.
Sa = ∫ (I _out ) dt + η × ∫ (I _in ) dt (Formula 2)
The correction value Sd is given by the following equation.
Sd = I _out + η × I _in (Expression 3)

  Here, it is assumed that the battery state control unit 22 performs control so that the remaining amount of the battery B is constant. FIG. 5 is a diagram illustrating the relationship between the detected remaining amount and the charging efficiency η. When the charging efficiency η is updated by the charging efficiency calculation unit 35, the charging efficiency η reflecting the change with time of the battery B at the time of updating is used. In the example of FIG. 5, the solid line indicated as η fluctuation indicates a case where the charging efficiency calculation unit 35 updates the charging efficiency η, and correctly detects that the remaining amount of the battery B is substantially constant. On the other hand, when the charging efficiency η is fixedly used and the change with time is not considered as in the prior art, and when the charging efficiency η itself is not taken into account, an error occurs in the detected value of the remaining battery B over time. (Dotted line shown as η fixation in FIG. 5).

  As will be described later, in this embodiment, the charging efficiency η is updated when a predetermined condition is satisfied. By updating, it is possible to cope with the change with time of the charging efficiency η, and the error can be reduced as compared with the case where the charging efficiency η is fixedly used.

(About the processing of the charging rate detection device)
In the charging rate detection apparatus 10 of the present embodiment, “the second estimated open circuit voltage OCVv is within a predetermined range from the value at the start of integration after fluctuation (hereinafter referred to as condition (a)). And “Charging current integrated value ∫ (I _in ) dt and discharge current integrated value ∫ (I _out ) dt are larger than predetermined values (hereinafter referred to as condition (b))” are satisfied. The charging efficiency calculation unit 35 updates the charging efficiency η. Here, the condition (a) means that the charging rate has returned to near the start of integration, that is, it remains discharged or not charged, and the condition (b) is divided when calculating the charging efficiency. This means that the absolute value of the value to be divided and the value to be divided are sufficiently large, and the accuracy of the division result is ensured even if the value does not return to the same voltage. In other words, if sufficient accuracy cannot be obtained even when the open-circuit voltage charging rate SOCv and the current integrated charging rate SOCi are calculated using the updated charging efficiency η, the charging rate detection device 10 sets the charging efficiency η to Do not update.

  The “predetermined range” in the condition (a) is a range that is sufficiently close to the charging rate before the start of integration, that is, a range in which it is meaningful to compare the integrated charge current and discharge current. This is because when the charging rate is greatly deviated from the value before the start of integration, the accurate charging efficiency η cannot be obtained even if the charging current integrated value and the discharge current integrated value are compared. FIG. 6 exemplifies a change in the second estimated open circuit voltage OCVv of the battery B, but the condition is a range of −ΔV to + ΔV centered on Vtg (the value of the second estimated open circuit voltage OCVv obtained at the start of integration). This corresponds to the “predetermined range” in (a). Note that ΔV may be zero.

  On the other hand, the “predetermined value” in the condition (b) sets the charging efficiency η even if the second estimated open circuit voltage OCVv does not return to the value before the start of integration (even if there is a slight deviation in the charging rate). This value is set so that the deviation can be ignored when obtaining. That is, if the integrated amount of the charging current and the discharging current is sufficiently large, it is expected that the charging efficiency η will be an almost accurate value even if there is a slight deviation in the charging rate. The “predetermined value” in the condition (b) is set so that the integrated amount of the charging current and discharging current is increased to that extent.

  Here, with reference to FIG. 6, the relationship between said conditions (a) and (b) and the calculation process of charging efficiency (eta) is demonstrated. First, it is assumed that the time ta is the start of integration, and the value of the second estimated open circuit voltage OCVv at this time is Vtg. Thereafter, it is assumed that the value of the second estimated open circuit voltage OCVv falls below Vtg−ΔV at time tb and returns to Vtg−ΔV at time tc. At this time, the condition (a) is not satisfied in the zone Z0 between the times tb and tc. Here, since the integration by the charging current integration unit 33 and the discharge current integration unit 32 has just started at time ta, the condition (b) is not satisfied in the zone Z0. Therefore, the calculation process of charging efficiency η is not performed.

  Thereafter, the value of the second estimated open circuit voltage OCVv returns to Vtg at time td, and further increases to Vtg + ΔV at time te. In the zone Z1 from time tc to te, the value of the second estimated open circuit voltage OCVv is within the range of Vtg−ΔV to Vtg + ΔV (predetermined range of the condition (a)), and charging is performed because the condition (a) is satisfied. An efficiency η calculation process is performed.

  Then, the value of the second estimated open circuit voltage OCVv returns to Vtg + ΔV at time tf, and returns to Vtg at time tg. Assuming that the section after the time te is the section Z2, in the section Z2, the condition (a) is not satisfied at least between the times te and tf. However, after time te, the condition (b) is satisfied because the charging current integration unit 33 and the discharge current integration unit 32 perform integration from time ta. Therefore, calculation processing of charging efficiency η is performed in the section Z2.

  FIG. 7 is a flowchart showing processing of the charging rate detection device 10 provided in the battery B mounted on the vehicle. First, the charging rate detection device 10 is on standby until the vehicle starts operating (No in step S2). When the vehicle starts to operate (Yes in step S2), it is determined whether a predetermined time has elapsed since the previous operation (step S4).

Here, the predetermined time is a period during which the state of the battery B is considered to have changed significantly while the vehicle is not operating. For example, if the vehicle has not been operated for a week, the lead-acid battery state may have changed significantly due to self-discharge such as dark current. In such a case, since the charging rate detection device 10 cannot receive the current IB while the vehicle is not operating, the stored charging current integrated value ∫ (I _in ) dt, discharge current integrated value ∫ (I _out) ) There is a possibility that dt, current integrated charge rate SOCi, and the like do not match the actual state of battery B. Therefore, when a predetermined time has elapsed from the previous operation (Yes in step S4), the data in the charging current integrating unit 33, the discharging current integrating unit 32, and the storage unit 38 are reset (step S6).

After step S6 or when the predetermined time has not elapsed since the previous vehicle operation (No in step S4), the charging rate detection device 10 acquires the terminal voltage VB and current IB of the battery B. The second estimated open circuit voltage OCVv, the charging current integrated value ∫ (I _in ) dt, and the discharge current integrated value ∫ (I _out ) dt are obtained (step S8).

  If the second estimated open-circuit voltage OCVv is within a predetermined range from the estimated open-circuit voltage at the start of integration (Vtg in FIG. 6) (Yes in step S10), the charging efficiency η is calculated, and according to the selection signal Sel. Then, the updated open-circuit voltage charging rate SOCv or current integrated charging rate SOCi is output as the charging rate SOC (step S16).

If the second estimated open circuit voltage OCVv is not within a predetermined range from the estimated open circuit voltage at the start of integration (No in step S10), the charging current integrated value ∫ (I _in ) dt and the discharge current integrated value ∫ (I _out ) It is determined whether the magnitude of dt is larger than a predetermined value (step S12). If the size is larger than the predetermined value in step S12 (Yes in step S12), step S16 is executed. Execution of step S16 corresponds to the calculation of the charging efficiency η by satisfying at least one of the condition (a) or the condition (b).

  On the other hand, if the magnitude is equal to or smaller than the predetermined value in step S12 (No in step S12), it is further determined whether the data in the storage unit 38 (past current integrated charging rate SOCi) is reset. (Step S14). If the data in the storage unit 38 has not been reset (No in step S14), the stored past current integrated charge rate SOCi is output as the charge rate SOC (step S18). This is because, if the state of the battery B has not changed significantly, it is considered that the current integrated charging rate SOCi calculated in the past is sufficiently close to the current charging rate of the battery B. On the other hand, when the data in the storage unit 38 is reset (Yes in step S14), there is no data that can be output to the storage unit 38, and the charging efficiency η is not calculated. Therefore, the open-circuit voltage charging rate SOCv is set as the charging rate SOC. (Step S20).

  After steps S16, S18, and S20 are executed, if the operation of the vehicle stops, the series of processes is terminated (Yes in step S22). If the vehicle is operating (No in step S22), the process returns to step S8. Return.

Here, when a predetermined time has elapsed since the previous operation of the vehicle (Yes in step S4), the charging current integration unit 33 and the discharge current integration unit 32 are reset (step S6), but otherwise Is stored with the charge current integrated value ∫ (I _in ) dt and the discharge current integrated value ∫ (I _out ) dt. That is, even if the vehicle is only operated for a short distance in a single operation, a cumulative integration (continuous integration) is performed for repeated short-distance travel, so that a sufficiently large charging current integrated value ∫ (I _in ) dt The discharge current integrated value ∫ (I _out ) dt can be obtained. As a result, the influence (relative magnitude) of the error (such as not returning to the original charging rate) can be reduced, and as a result, the error of the calculated charging efficiency η can also be reduced. .

  As described above, according to the charging rate detection device 10 and the charging rate detection method of the present embodiment, since the charging efficiency η for the battery B being used is obtained by calculation rather than during replacement, power is wasted. In addition, the deterioration of the lead storage battery is not promoted, and the change in charging efficiency η over time can be handled. Further, since the calculation based on the fully charged state is not required, the battery B can be used in an incompletely charged state.

  Although the present invention has been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various modifications and corrections based on the present disclosure. Therefore, it should be noted that these variations and modifications are included in the scope of the present invention. For example, functions and the like included in each means and step can be rearranged so as not to be logically contradictory, and a plurality of means and steps can be combined into one or divided.

DESCRIPTION OF SYMBOLS 10 Charge rate detection apparatus 12 Open circuit voltage estimation part 14 SOCv calculation part 16 Current integration part 18 SOCi calculation part 20 SOC selection part 22 Battery state control part 24 Filter part 26 OCV-SOC conversion part 31 Separation conversion part 32 Discharge current integration part 33 Charging current integrating unit 35 Charging efficiency calculating unit 38 Storage unit Alt alternator B Battery

Claims (8)

A charging current integrating unit that integrates the charging current of the lead acid battery in operation and generates a charging current integrated value;
A discharge current integrating unit that integrates the discharge current of the lead storage battery and generates a discharge current integrated value;
A charging efficiency calculation unit that calculates charging efficiency obtained by dividing the magnitude of the discharge current integrated value by the magnitude of the charging current integrated value when at least one of the conditions (a) and (b) is satisfied;
Including
The condition (a) is that the estimated open-circuit voltage of the lead storage battery is within a predetermined range from the open-circuit voltage estimated at the start of integration after a change.
The condition (b) is characterized in that the absolute value of the discharge current integrated value and the absolute value of the charge current integrated value are large enough to ensure the accuracy of the division . The charging rate detection device according to claim 1,
An open-circuit voltage estimation unit for estimating an open-circuit voltage from the detected current and voltage of the lead storage battery,
A charge rate detection device that calculates a first charge rate based on an open circuit voltage estimated by the open circuit voltage estimation unit. In the charging rate detection device according to claim 2,
A filter unit having a filter that adjusts the change amount of the open-circuit voltage estimated by the open-circuit voltage estimation unit based on the change amount of the charge current integrated value, the change amount of the discharge current integrated value, and the charging efficiency;
A charging rate detection device that calculates the first charging rate based on the open circuit voltage that has passed through the filter. In the charging rate detection device according to claim 2 or 3,
When the charging efficiency calculation unit calculates the charging efficiency, the second charging rate calculated based on the charging current integrated value, the discharge current integrated value, and the charging efficiency, or the first charging rate Is a charge rate detection device that selectively outputs. In the charge rate detection device according to any one of claims 1 to 4,
The lead storage battery is mounted on a vehicle,
The charging current integrating unit and the discharging current integrating unit are
A charging rate detection device that continuously integrates the charging current and the discharging current in a plurality of operations of the vehicle. In the charge rate detection apparatus according to any one of claims 1 to 5,
The charge rate detection apparatus containing the battery state control part which controls so that the open circuit voltage of the said lead acid battery is constant. In the charging rate detection device according to any one of claims 1 to 6,
The charging efficiency calculation unit is a charging rate detection device that calculates the charging efficiency when the conditions (a) and (b) are satisfied. (A) integrating the charging current of the lead acid battery in operation, and generating a charging current integrated value;
(B) integrating the discharge current of the lead storage battery to generate a discharge current integrated value;
(C) calculating at least one of the conditions (a) and (b) and calculating the charging efficiency obtained by dividing the magnitude of the discharge current integrated value by the magnitude of the charge current integrated value;
Including
The condition (a) is that the estimated open-circuit voltage of the lead storage battery is within a predetermined range from the open-circuit voltage estimated at the start of integration after a change.
The condition (b) is characterized in that the absolute value of the discharge current integrated value and the absolute value of the charge current integrated value are large enough to ensure the accuracy of the division .

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