CN101447688A - Method and apparatus for detecting internal electric state of in-vehicle secondary battery - Google Patents
Method and apparatus for detecting internal electric state of in-vehicle secondary battery Download PDFInfo
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Abstract
The invention relates to an apparatus and a method for detecting internal electric state of in-vehicle secondary battery. In a proposed apparatus and method, constant-voltage charge is performed with an in-vehicle secondary battery immediately after start of a vehicle or during running of the vehicle. A quantity relevant to polarization caused in the battery immediately after start of the constant-voltage charge is calculated using data of the charge current. It is determined whether or not a change rate of the calculated polarization-relevant quantity is less than a given threshold. When the change rate is less than the given threshold, a plurality of data of the charge current sampled and held during a predetermined period of time are acquired. A value of the charge current to be accumulated until the charge current reaches a given final value is calculated using the plurality of data of the charge current. The internal electric state of the battery is estimated based on the accumulated value of the charge current.
Description
Technical field
The present invention relates to a kind of device and method that is used to detect the internal electric state of in-vehicle secondary battery.
Background technology
In recent years, storage battery (rechargeable battery) capacity that is installed in the vehicle improves constantly, to satisfy the increase that is installed in the electrical load quantity in the vehicle.Therefore, in the last few years, prevent in-vehicle secondary battery overcharge and over-discharge can become extremely important.Therefore detection expression internal storage battery electric state is reliable with information is very necessary accurately, and these information comprise that storage battery remains the information of charging capacity.
In this case, Japanese patent application No.3249788 discloses a kind of conventional method of estimating to represent the information of in-vehicle secondary battery internal electric state.The method of estimation that the disclosure proposed is used the discharging current variation characteristic, and this characteristic is relevant with the waveform of the constant voltage charge discharging current variation constantly before of battery.Hereinafter, this variation characteristic is called " charging current approximate function ".Utilize this charging current approximate function to estimate that charging current becomes the time (estimated time) of given final value, and calculate reach the capacity that is recharged (charging capacity) of finishing rate and be used to charge in case of necessity between.
But in the situation of aforementioned techniques, the charging current approximate function that is used to estimate is subjected to the influence (i.e. fluctuation) of battery polarization state scrambling easily, causes function to depart from the actual charge current waveform.Therefore, in most of the cases, actual charge current reaches the time (being the real time) of set-point and has very big difference between estimated time.Thereby make charging capacity and based on the aforementioned estimation Time Calculation be used to charge in case of necessity between accuracy reduce.
In addition, in the aforementioned open technology that is proposed, be under the situation of not considering the influence of battery charge efficiency variance, to estimate the charging current characteristic.Therefore, distinguishingly, in the latter stage of charging action, the charging current approximate function must have lower accuracy.To charging capacity and be used to charge in case of necessity between estimation more inaccurate.
Summary of the invention
Consider that aforementioned common technology has proposed the present invention, one of purpose of the present invention provides a kind of device that is used to detect the internal electric state of in-vehicle secondary battery, and this device can estimate exactly that during constant voltage charge charging current reaches the moment of given final value.
To achieve these goals, on the one hand, the invention provides a kind of device that is used to estimate the internal electric state of in-vehicle secondary battery, the terminal voltage of regulating this in-vehicle secondary battery by the alternating current generator of operation vehicle is a desired value, this device comprises: current detector, and it detects charging current that flows into this battery and the discharging current that flows out from this battery; Sampling apparatus, the electric current that it is detected by this current detector with certain hour interval sampling and maintenance; Charging device, it carries out constant voltage charge to a predetermined value to this battery, this predetermined value after vehicle launch immediately or offer this battery during the vehicle '; First calculation element, the relevant polarization correlative of quantity of the polarization that battery, causes immediately after it utilizes the charging current data computation that obtains from sampling and holding device and constant voltage charge starts; Decision maker, whether the rate of change of the polarization correlative that its judgement calculates is lower than given threshold value; Its a large amount of charging current data that are captured in sampling during the predetermined amount of time and keep from this sampling and holding device when harvester, the rate of change of judging the polarization correlative that calculates are lower than this given threshold value; Second calculation element, the charging current value that it utilizes the data computation of these a large amount of charging currents to accumulate when charging current reaches given final value; And estimation unit, it estimates the internal electric state of this battery based on the charging current accumulated value that calculates.
On the other hand, the invention provides a kind of method that is used to estimate the internal electric state of in-vehicle secondary battery, the terminal voltage of regulating this battery by the alternating current generator of operation vehicle is a desired value, and this method comprises the step similar to the element of said apparatus.
In the present invention, the slack-off gradually state of variation of monitoring constant voltage charge starting after-polarization correlative.Afterwards, utilize the later stage in the charging current to change, estimate this moment the variation of charging current afterwards.Utilize this estimated result to detect or determine the internal electric state of in-vehicle secondary battery.Therefore, for the internal electric state of estimating battery, the irregular influence of polarization that occurs in the battery when eliminating charging reliably is possible to improve the accuracy that detects.The internal electric state of battery can be for example SOC (charged state), SOH (health status) and the amount (for example from battery full charge capacity deduct amount that SOC or SOH obtain) relevant with SOC and SOH.
Preferably after engine start, carry out constant voltage charge immediately.When engine quits work, for battery charge and all very faint from battery discharge be normal, the polarization in this moment battery almost can be regarded as zero.Therefore, it is possible improving the accuracy of calculating the polarization correlative, to improve the accuracy of the internal electric state that detects battery.
On the other hand, the invention provides a kind of device, be used to estimate the device of the internal electric state of in-vehicle secondary battery, the terminal voltage of regulating this battery by the alternating current generator of operation vehicle is a desired value, this device comprises: current detector, and it detects charging current that flows into battery and the discharging current that flows out from electric current; Sampling apparatus, the electric current that it is detected by this current detector with certain hour interval sampling and maintenance; Charging device, it carries out constant voltage charge to a predetermined value to battery, this predetermined value after vehicle launch immediately or offer this battery during the vehicle '; Calculation element, its a large amount of charging current data computation based on constant voltage charge starting post-sampling and maintenance are represented the charging current function of charging current transient change; Storage device, it stores corrected value relevant with cell degradation or correction function in advance; Means for correcting, it proofreaies and correct this charging current function according to this corrected value or correction function; Collecting apparatus, it is based on the charging current of charging current function accumulation when charging current reaches given final value of this correction; And estimation unit, it utilizes the accumulated value of charging current to estimate the internal electric state of this battery.
Therefore, with respect to the situation of the charging current function not being proofreaied and correct, it is possible improving calculating charging current accumulated value accuracy.Do not need for a long time that constant voltage charge finishes up to charge cycle, thereby improve the availability of battery, and avoid causing cell degradation owing to carrying out long-time constant voltage charge continually.
Description of drawings
In the accompanying drawings:
Accompanying drawing 3 typically illustrates the figure of the battery charge characteristic that the constant voltage charge control period provides;
Accompanying drawing 4 shows the figure of the differential value characteristic of charging current characteristic, polarization factor characteristic and polarization factor that explanation obtains by constant voltage charge;
Accompanying drawing 5 shows normal charge current characteristics (A), the charging current characteristic (B) of explanation according to first embodiment with manner of comparison, and the figure of the charging current characteristic (C) of actual measurement;
Accompanying drawing 6 is flow charts of describing the constant voltage charge control of being undertaken by processor, and this processor is incorporated in the SOC calculation element, and this SOC calculation element is used for the device according to the internal electric state of battery in the car of second embodiment of the invention;
Accompanying drawing 7 shows the charging current characteristic (A) of constant voltage charge control period actual measurement, the charging current characteristic (B) of utilizing the charging current function correction of proofreading and correct and the figure that utilizes the charging current characteristic (C) of charging current function correction;
Accompanying drawing 8 shows the figure that concerns between exemplary charge current value and the correction coefficient; And
Accompanying drawing 9 provides four of examples that the figure of the mapping (m1 to m4) of different relations between charging current and the correction coefficient is provided.
Embodiment
With reference to accompanying drawing, embodiments of the invention are described now, it is according to the device of the internal electric state that is used to detect in-vehicle secondary battery.
First embodiment
1-5 describes the first embodiment of the present invention now with reference to the accompanying drawings.In this embodiment, checkout gear according to the present invention is embodied as SOC (charged state) calculation element that is used for in-vehicle secondary battery.
Battery 101 is storage batterys that lead-acid battery, Ni-MH battery or lithium battery are formed.The storage battery of any kind all is suitable for present embodiment, but in the present embodiment, vehicle adopts lead-acid battery.
Store status detector 105 comprises buffer 106, by buffer 106 the voltage and current signal is inputed to store status detector 105, also comprise processor 107, it carries out various calculating as the important computations parts in the SOC calculation element 1 according to the polarization that battery 101 inside cause.
Generator control unit 109 is used to control the output of generator 102.Just, generator control unit 109 imposes on the exciting current of generator 102 with feedback system control, and the voltage that makes battery 101 is zero with difference between the given regulation voltage set.Therefore, the voltage of battery 101 is controlled as given regulation voltage.In addition, generator control unit 109 provides control signal according to the energy output that ECU108 calculates to generator 102, and this control signal makes generator responds generate electricity in the aim parameter of control signal indication.
In the practice, in store status detector 105, realize by software on buffer 106 and processor 107 functions that this software is calculated by the microcomputer that is incorporated into store status detector 105.Certainly, the replaceable structure of store status detector 105 is that dedicated computing hardware circuit or the alternate manner that is provided by logical circuit is provided.
The paired data that buffer 106 is configured to sample at set intervals and the electric current I that keeps voltage V and current sensor 104 by battery 101 to detect is formed.As hereinafter describing in detail, processor 107 comes the SOC of counting cell 101 as input parameter by the paired data (voltage V and electric current I) that utilizes buffer 106 to provide.
＜constant voltage charge control 〉
With reference to the accompanying drawings 2, the operation of the constant voltage charge control that belongs to the present embodiment feature is described in detail in detail.
When being used for the subprogram starting of constant voltage charge control, processor 107 for example utilizes mark check to determine that whether constant voltage charge control is at present in operation (step S1).If determine the result for being (in operation), program advances to step S2, and if determine that the result is not (off-duty), program advances to step S3, starts constant voltage charge here and controls permanent width of cloth voltage is applied to battery 101.By way of parenthesis, carry out this constant voltage charge control, the generating of control generator 102 (alternating current generator) is a constant voltage with the voltage of keeping battery 101.
In addition, execution in step S1 comprises whether inspection exists unexpected connection or the disconnection or because the unexpected variation of the generating voltage of the generator 102 that the unexpected variation of engine speed (speed of generator rotation) causes of load.When in step S1, confirming to have so unexpected variation, even controlling to so far, constant voltage charge moving, still suppose the present and off-duty of constant voltage charge control.In this case, program advances to step S4.This supposition is handled and is considered because the caused delay of time constant in the exciting current of control generator 102.By the way, when this unexpected variation takes place for energy output and loading condition, preferably suspend the constant voltage charge control shown in the accompanying drawing 2, through one preset time section restart again later on.
In step S2, processor 107 is read the charging current Icv that flows to battery 101.The polarized state amount) and its difference DELTA P in step S4, the charging current Icv that processor 107 utilization is read in calculates polarization correlative P (as the physical quantity of expression polarized state:.In the present embodiment, calculate polarization correlative P according to following formula (1):
Pn＝Pn-1+In*dt-1/T*Pn-I*dt...(1)
T express time constant wherein, n represents current polarization correlative, the last time polarization correlative of calculating in last the calculating in the accompanying drawing 2 that n-1 represents to repeat with given interval dt.Therefore, Pn represent the to polarize currency of correlative P, Pn-1 represent the to polarize last time value of correlative P, In represents the currency of charging current Icv.That is to say that the time difference between currency and the last value is dt.
By the way, in the initial calculation of formula (1), last value Pn-1 preferably is set to 0.In the present embodiment, consider to simplify and calculate that the computing cycle of the subprogram shown in the accompanying drawing 2 and the current sample cycle in step S2 are set to equal dt at interval.At length, T is the time constant of electric charge diffusion in the battery electrolysis, and is to be provided by the given numerical value that obtains by experiment in advance.By formula (1), add incremental change Indt among the last time value Pn-1 by last time sampling or subtract decrement Pn-1dt/T obtain the polarizing currency Pn of correlative P (polarized state amount), this incremental change Indt produces during the interval dt between the once last and current sampling operation, this decrement Pn-1dt/T last once time and the interval dt between the current sampling operation during decay.
Simultaneously, the difference DELTA P of polarization correlative P is represented by formula (2):
ΔP＝(Pn-Pn-1)/dt＝In-1/T*Pn-1...(2)
After this program advances to step S5, and wherein whether processor 107 definite difference DELTA P are reduced to and are lower than given threshold value Pth.If determine result's whether (being that decrease is greater than Pth), program turns back to main program.On the other hand, as definite result (decrease is less than Pth) when being, processor 107 assert that the polarization in the batteries 101 has been stabilized in the specified quantitative of charge polarization.In this case, the permission program advances to step S6, and wherein processor 107 is read the charging current amount Icv1 to Icv31 that samples and store during the predetermined amount of time T (for example 30 seconds), and this time period T starts from difference DELTA P and is reduced to the moment that is lower than threshold value Pth.
After this, processor 107 advances to step S7, wherein utilizes the charging current amount Icv1 to Icv31 that reads in to calculate the approximation formula
I＝K+a*exp(b*t)...(3)
Utilize prior art such as least square method (the least square approach), this approximation formula provides the transient change characteristic of charging current.In this approximation formula, I represents charging current, and K, a, b represent can be by the constant of determining as experiment, and t represents to begin institute's elapsed time from constant voltage charge.Constant K can be made as 0.
Program advances to step S8, and wherein processor 107 will be scheduled to charging current final value Icv and be updated to the approximation formula that has obtained, and at current time, estimates the termination moment Tf that constant voltage charge control will finish.In step S8, processor 107 also carries out the integration to charging current Icv during the time period of the moment of the termination from current time to control Tf, to obtain the integrated value (being a=∫ Icvdt) of charging current Icv.
Charging current final value Icv is set to the numerical value that obtains when the SOC of battery 101 in the state of carrying out constant voltage charge control under afore-mentioned is 90%.This charging current final value Icv shifts to an earlier date by experiment or other modes are provided with.Therefore, at step S9,, accurately calculate current SOC by the integrated value (a=∫ Icvdt) that from SOC 90%, deducts charging current Icv.In addition, in step S9, the amount of capacity of also estimating inductive charging from now on is to obtain 90% SOC.At step S10, constant voltage charge stops then.
In the present embodiment, in this way, can be in various situations the accurate charged state of estimating battery 101.These situations comprise the instant moment after the engine start when capacity of battery 101 reduces, and wherein need a predetermined charging capacity.These situations also comprise particularly increases a large amount of electrical loads during vehicle '.In these situations, be battery 101 chargings more by the energy output that increases generator 102, with reducing of balancing battery SOC.More specifically, if because continuous and constant pressure charging having caused discharge polarization in above-mentioned charge step, the discharge polarization can disappear very soon, so that the moment of the predetermined amount of time of process provides the stable charging polarized state of generation corresponding to the polarization specified quantitative of charging voltage afterwards in the constant voltage charge starting.In the present embodiment, whether detect the time that stabilisation is finished by the variation of checking polarization correlative P less than predetermined threshold Pth.
In addition, have only when having realized having the stable state of charge polarization specified quantitative, just sample charging current to obtain necessary sample rate current data with given interval.Utilize these sample rate current data to estimate the charging current characteristic.Utilize the integrated value (a=∫ Icvdt) of the interior charging current of necessity during the time period of this characteristic estimating from current time to the moment that reaches predetermined SOC value (for example 90%) then.Therefore estimate current SOC value exactly and reach constant voltage charge that the necessary total amount of electric charge of predetermined SOC value that is provided is provided immediately is possible.Can not be subjected to polarized state scrambling influence and estimate.Also can utilize this technology for detection to overcharge.
With reference to the accompanying drawings 3, actual more advantage is described now.
Accompanying drawing 3 examples when the charging current characteristic that the battery that also is not full of electricity is obtained when carrying out constant voltage charge.When the starting constant voltage charge, because charging capacity increases and produces charge polarization, can produce an initial charge scope, the figure of expression charging current characteristic shows the minimizing of charging current.Distinguishingly, the influence that the generation polarization is produced in lead-acid battery is greater than the battery of other kinds.The conventional approximation formula of the charging current that obtains under the constant voltage charge state is not considered the influence of the scrambling that polarizes.
On the contrary, present embodiment adopts after the predetermined time interval section of constant voltage charge starting beginning the charging current data with the certain hour interval sampling.Predetermined amount of time is set, thereby can eliminates the influence of the scrambling of polarized state with reliable fashion.Utilize the sampled data that obtains in this way to determine charging current characteristic (being the approximation formula), and utilize the internal electric state of this charging current characteristic estimating battery 101.As a result, can eliminate the influence of the scrambling of the polarized state that occurs in the initial range of constant voltage charge, thus make under the constant voltage charge situation more accurate for the estimation of charging current characteristic.
＜experimental result 〉
Accompanying drawing 4 shows the experimental result of the charge volume of realizing under the constant voltage charge situation.In the experiment situation of accompanying drawing 4, at first start constant voltage charge, begin 30 seconds store electricity flow valuves from difference (polarization index) vanishing or littler moment of the polarization correlative that obtains by charging current value.Based on the current value of being stored, obtain approximation formula I (t)=A*exp (B*t).Calculate the capacity that is accumulated when the current value that obtains based on this approximation formula reaches set-point 5A, it is 6.4Ah.This numerical value is the charging capacity 6.5Ah of actual measurement no better than, therefore is appreciated that and can more accurately estimates charging capacity.
In addition, accompanying drawing 5 shows the relative result that experimentizes in the lead-acid battery in identical car, wherein shows charging current characteristic A to C.Charging current characteristic A shows based on known technology and does not consider to polarize and the experiment carried out, and charging current characteristic B shows another experiment of carrying out according to present embodiment, and charging current characteristic C shows another experiment of actual measurement discharging current.In the situation of routine techniques (being characteristic A), constant voltage charge continues a given time period T, measures charging current during this period, utilizes charging current value and time T to calculate the approximation formula.In this regular situation, to compare approximation more inaccurate with the charging current (characteristic C) of actual measurement.On the contrary, (being characteristic B) in an embodiment of the present invention, as mentioned above, the charging current value based on detecting during the predetermined amount of time Tp that begins from moment of Δ P＜0 and relevant time obtains the approximation formula.Very obvious, approach the charging current characteristic C of actual measurement according to the approximation of present embodiment, thereby improved approximate accuracy.
The minimizing of the amount of polarization before the starting of＜constant voltage charge 〉
In the present embodiment, can calculate the currency Pn of polarization correlative P based on aforementioned formula (1).Formula (1) once is worth Pn-1 on need determining before calculating currency Pn.The calculating of formula (2) is correct.In calculating the first time that the current data that formula (1) detects based on first and second sense cycle is carried out, also do not calculate last value Pn-1.But,, can be worth that Pn-1 regards constant as the last time or be 0 because charging current/discharging current is almost constant or very little.
Therefore, at once, the integrated value of the charge/discharge current of battery can be regarded as approximate constant in the car that stored charge has consumed by piloting engine after the engine start.Simultaneously, because battery is not worked for a long time, can think that the polarization in the battery disappears.According to this viewpoint, can suppose to make battery discharge produce the discharge polarization of constant afterwards at once in order to pilot engine.This amount of polarization can be set to a set-point.In addition, at once, battery always can carry out a certain amount of discharge from the state that is full of electricity after the engine start.After this discharge, battery carries out constant voltage charge.This charging must offer the integrated value of quantitative charging current, and this is the later advantage of carrying out constant voltage charge at once of engine start just.
Also can utilize formula (1) to calculate the currency of the polarization in the discharge of being carried out of piloting engine.The discharge amount of polarization of utilizing this mode to calculate can be distributed to the currency of the polarization correlative in the starting constant voltage charge.Therefore, as once being worth Pn-1 on the correlative that needs in the sense cycle for the second time of current data under the constant voltage charge situation to polarize, in discharging action, adopt the currency Pn of aforementioned polarization correlative P.
When vehicle ', the SOC of in-vehicle secondary battery gets different value.During vehicle ', the increase of electrical load or the minimizing of energy output will need battery to carry out the discharge of a period of time.In this case, should charge to remedy reducing among the SOC to battery.Therefore being preferably in discharging action has continued a preset time and has restarted constant voltage charge during section.
When discharging action has continued a preset time during section, the discharge polarization that can produce specified rate in battery.Therefore, be preferably in after such charging action, keep charge/discharge current to be littler value in preset time in the section, to eliminate by the caused polarization of constant voltage charge of discharging and carrying out afterwards.
In addition, also have a time period, during charge/discharge current very little so that can think the polarization disappear, this time period last till keep one preset time section discharging action before.In this case, in the moment of the lasting beginning of above-mentioned polarization, be 0 with polarization setting, to utilize aforementioned formula (1) (wherein symbol is opposite) calculating amount of polarization, the polarization correlative when calculating the gained amount and being used as the constant voltage charge starting.That is to say that this calculating gained amount can be used as on the polarization correlative P that second sense cycle of charging current under the constant voltage charge situation is calculated and once be worth Pn-1.
Further, can use regulation voltage Vref+ Δ V to carry out aforementioned constant voltage charge, this regulation voltage Vref+ Δ V is higher than the standard adjustment voltage Vref of generator.In this case, if when vehicle ' the preset time of starting before the constant voltage charge during the section charge/discharge current be lower than a set-point, can think that then polarization disappears.Therefore, the polarization correlative P that uses of charging current second sense cycle after constant voltage charge starting on once be worth Pn-1 and can be set to 0.When adopting regulation voltage Vref+ Δ V, the charging current corresponding with charging voltage difference DELTA V flows during constant voltage charge always, so that preferably adopt regulation voltage Vref+ Δ V.
Can also be provided at and use the approximation formula to estimate the correction of the previous embodiment of charging current characteristic under the constant voltage charge control situation.But this is not unique embodiment.For example, can prepare form or equation in advance, the charging current of (for example 30 seconds) reduces relation between dIcv and the cumulative capacity during the absolute value of this form or equation definition charging current value Icv1 to Icv31, the preset time section.Can obtain the charging current characteristic from this form or equation.
(second embodiment)
6-8 describes second embodiment according to checkout gear of the present invention now with reference to the accompanying drawings.
As first embodiment, in a second embodiment, checkout gear is realized as the SOC calculation element that is used for in-vehicle secondary battery.In addition, easy for describing, still use identical Reference numeral with the similar or similar elements of SOC calculation element among first embodiment.
Except processor 107 based on the flow chart work as shown in Figure 6, the device 1 that the hardware configuration of SOC calculation element and accompanying drawing 1 described is identical.In addition, step S11-S16 is identical with content among the step S1-S6.In these steps, be 107 identifications of processor complete obiteration that polarizes, and advance to step S16 if in step S15, be defined as.First embodiment as described above, in this step, processor 107 reads out in the charging current amount Icv1 to Icv31 that is reduced to sampling and storage during the predetermined amount of time T (for example 30 seconds) that moment of being lower than threshold value Pth begins from difference DELTA P.
After this, processor 107 advances to step S17, wherein utilize the charging current amount Icv1 to Icv31 that reads in to calculate approximation formula I=K+a*exp (b*t) (it is identical with formula (3)), and adopt the transient change characteristic of this approximation formula, promptly according to charging current function of the present invention as charging current.By the way, this charging current function always is not subject to aforementioned approximation formula, can also be provided by the various known approximation method of the current data of estimating to detect during constant voltage charge.
After this program advances to step S18, the processor 107 approximation formula (being the charging current function) that utilizes correction coefficient to come correction calculation to go out wherein, and this correction coefficient is stored in the memory of processor 107 for example in advance.This trimming process produces the correction function (abbreviating the charging current function of correction as) that is used for charging current.The charging current function of this correction can write in the mapping table, and does not need to use mathematical formulae.Later in detail this correction coefficient will be described in detail.
After this, at step S19, processor 107 with the final value substitution of predetermined charging current Icv to the charging current function of proofreading and correct, to determine termination that ongoing constant voltage charge control should stop Tf constantly.In addition, under the situation that the control of hypothesis constant voltage charge continues for some time, at time period inner accumulated charging current Icv from current time to termination moment Tf.As previously described, thus by calculate by a ∫ Idt charging current accumulated value a as obtain and.
Therefore, in step S20, by from SOC 90% deduct the integrated value a (a=∫ Idt) of charging current Icv, can accurately calculate current SOC.In addition, in step S20, also estimate from obtaining 90% amount of capacity that also should charge of SOC so far.After this, in step S21, constant voltage charge stops.For the sample rate current data, can also when proceeding to step S16, stop constant voltage charge.
＜how to obtain correction coefficient 〉
The correction coefficient of proofreading and correct charging current function (approximation formula) is described now.Utilize correction coefficient to proofread and correct the slowness that charging current reduces when constant voltage charge stops, this slowness is owing to some factors that comprise the charge characteristic that in-vehicle secondary battery is aging.Can utilize several different methods to obtain this correction coefficient, wherein some will be described in detail in detail below.
Be first method below.When will be based on each the different current data constantly under the constant voltage charge, the charging current that obtains from the charging current function be during as benchmark, and charging current is positive correlation with respect to the accumulated time of the charge/discharge of the increment rate of this benchmark and in-vehicle secondary battery.Long more when the charge/discharge cycle life-span, then this increment rate is big more.
The charging current function Iy that proofreaies and correct is expressed as:
I
Y＝K′+a′*exp(b′*t)...(4)
Wherein K ', a ' and b ' are coefficients, and wherein K ' is coefficient or function, and its variable is initial coefficients K, and a ' is coefficient or the function of initial coefficients a, and b ' is coefficient or the function of initial coefficients b.In formula (3), initial coefficients K, a and b have been shown.In order to simplify calculating, preferably each function all is a function of first order.Certainly, also can utilize mapping to determine coefficient.
When adopting function or mapping rather than constant value, can produce function or mapping as follows.
For example, can distinguish produce in advance COEFFICIENT K ', function of first order or the mapping of a ' and b ', wherein their variable is set as the accumulated time T of the charge/discharge current of battery.The function or the mapping that produce are stored in the memory that for example is incorporated in the processor 107.In this case, with the time T substitution or be applied to function or mapping, can determine uniquely like this COEFFICIENT K ', a ' and b '.
Can make ins all sorts of ways estimates the accumulated time T of charge/discharge current.For example, during the time period of trigger switch conducting, usage counter calculates the accumulated time value that charge/discharge current surpasses predetermined value.This counting can be regarded as charge/discharge current accumulated time no better than.
One or two among correction coefficient K ', a ' and the b ' only.For example, can set correction coefficient Y according to a '=Ya with respect to coefficient a.
Correction coefficient can when manufacturing works transport with regard to write memory.Selectively, use the mathematical formulae of storage in advance, can utilize the status signal that in car, detects the battery at its duration of work to come the calculation correction coefficient.In this case, status signal is the signal of voltage, electric current, temperature and/or the operating time of expression battery.Another kind method is to carry out long constant voltage charge control temporarily, the charging that always lasts till battery (for example finishes, arrive the moment of the SOC of acquisition 90%), and the charging current value that utilizes control period to obtain can be released mathematical formulae or the mapping that provides coefficient.
Be second kind of technology below.With the charging current that obtains from the charging current function under the constant voltage charge situation during as benchmark, with respect to the maximum of the charging current of this benchmark and increment rate all with the positive correlation that increases to of used time of constant voltage charge.The used time of constant voltage charge is long more, and then maximum and increment rate are big more.
The charging current function Iy that formula (4) expression is proofreaied and correct is identical with the mode of being explained in the first method.When adopting function or mapping rather than constant value, can produce function or mapping as follows.For example, first method as described above, can produce respectively in advance these COEFFICIENT K ', function of first order or the mapping of a ' and b ', and according to using them with the same mode of first method.
＜experimental result 〉
Accompanying drawing 7 shows measuring and estimate the experimental result of charging capacity under the normally used constant voltage charge situation that is installed in the lead-acid battery in the vehicle.
As shown in Figure 4, relevant with constant voltage charge experiment was carried out 480 seconds, during this period of time began a large amount of charging current value of sampling at a certain time interval from constant voltage charge.The every pair of charging current value and be used to calculate charging current function I (t)=A*exp (B*t) from the used time t of constant voltage charge starting.After this, by correction coefficient Y being applied to the charging current function I that charging current function I (t)=A*exp (B*t) acquisition is proofreaied and correct
Y(t)=Y*A*exp (B*t).Therefore, the charging current function I that proofreaies and correct by following formulate
Y(t) difference coefficient d I
Y(t):
dI
Y(t)＝Y*A*B*exp(B*t))＝I
Y(t)-I
Y(t-1)...(5)
I wherein
Y(t) currency of the charging current function of expression correction, I
Y(t-1) the last time value of the charging current function proofreaied and correct of expression, dt represents the computing cycle (repetition time) of the charging current function proofreaied and correct.
The charging current Function Estimation of utilizing this correction is to the charging current value of accumulating during charging current reaches time period till the charging current final value Icv.This electric current I cv is predetermined to be and equals the current value that obtained when charging action has realized 90% SOC.This estimation shows that the accumulated value (being charging capacity) of charging current is 5.8Ah.Compare, in the actual experiment that constant voltage charge continues, the charging current accumulated value that records is 6.2Ah.Because the difference of two kinds of situations has only 0.4Ah, represents that this estimation is very accurate.
Also utilize the accumulated value of aforementioned this charging current of charging current Function Estimation, but it is not proofreaied and correct.This estimation shows that accumulated value is 4.9Ah, its than the actual charging capacity 6.2Ah that records less than 1.3Ah nearly.
Accompanying drawing 5 shows the relation between the correction coefficient Y and the actual charging current that records during the constant voltage charge.By in advance carrying out constant voltage charge and determine correction coefficient Y in the accompanying drawing 5 for being installed in battery in the vehicle, the value of the charging current function calculation of actual charging current value that records that each Measuring Time point obtains during identical used time range and utilization correction is used to provide the program of least squares error.
In car in the battery, how to use battery or battery to use how long to influence the performance (for example the battery charge efficient and the internal resistance of cell) of battery, will change and make charging current during the constant voltage charge reduce characteristic (with reference to the accompanying drawings 7).Consider these situations, preferably proofread and correct aforementioned corrected coefficient Y according to the current internal electric state of battery, this state depends on for example its cycle operating time.Accompanying drawing 9 shows the example of this correction.
As shown in Figure 9, mapping m1 to m4 has defined the v.s. that concerns between a plurality of charging current amounts, and correction coefficient Y sets in advance.After the constant voltage charge, the charging current value that utilizes the actual charging current value that records and many batch totals to calculate is at once selected suitable mapping m1 (to m4), so that the suitable correction coefficient Y based on the mapping m1 (to m4) that selects to be provided.Carrying out this selection makes the square error between the charging current value that the actual charging current value that records and every batch total calculate become minimum.For the charging current value that obtains to calculate, calculate the charging current function from the actual charging current value that records, by using each the correction coefficient mapping m1 to m4 shown in the accompanying drawing 6 to proofread and correct this charging current function, with this function correction to be each calibrated charging current function.Utilize each calibrated charging current function, calculate the charging current value that many batch totals are calculated in the moment identical with the actual charging current value that records.
In the present embodiment, may be in all cases the charged state of estimating battery 101 exactly.These situations are included in the moment after engine starts immediately under the situation that the capacity of battery 101 reduces, and wherein need the charging capacity of being scheduled to.These situations also comprise the moment of having dropped into a large amount of electrical loads especially during vehicle '.In these situations, be battery 101 chargings more by the energy output that improves generator 102, with reducing of balancing battery SOC.
Present embodiment can further improve, and begins the charging current of sampling after the predetermined amount of time Δ T that begins from constant voltage charge, and perhaps the charging current that obtains when constant voltage charge begins in charging current moment of reducing given rate quantity begins the charging current of sampling.Adjust the influence of the polarization (charging polarization) that sampling instant can eliminate or reduce to cause in the constant voltage charge.
Can be with the present invention of other several mode examples, and do not depart from spirit of the present invention.Because scope of the present invention is limited by claim rather than aforementioned description, therefore described so far embodiment and improvement only are used for statement rather than restriction.Therefore the equivalence that enters all distortion of the border of claim and scope or these borders and scope all belongs to the scope of claim.
Claims (8)
1. device that is used to estimate the internal electric state of in-vehicle secondary battery, the terminal voltage of regulating this in-vehicle secondary battery by alternating current generator in the operation car is a desired value, this device comprises:
Current detector, it detects charging current that flows into this battery and the discharging current that flows out from this battery;
Sampling apparatus, the electric current that it is detected by this current detector with certain hour interval sampling and maintenance;
Charging device, it carries out constant voltage charge to predetermined value to this battery, this predetermined value after vehicle launch immediately or offer this battery during the vehicle ';
First calculation element, it is used to from sampling and the charging current data that obtain of holding device, calculates the relevant polarization correlative of quantity with the polarization that causes in battery immediately after constant voltage charge starts;
Decision maker, whether the rate of change of the polarization correlative that its judgement calculates is lower than given threshold value;
Harvester, be captured in predetermined amount of time from this sampling and holding device when its rate of change in the polarization correlative that determines calculating is lower than this given threshold value during sampling and a large amount of charging current data of keeping;
Second calculation element, the charging current value that it utilizes a large amount of charging current data computation to accumulate when charging current reaches given final value;
Estimation unit, its accumulated value based on the charging current that calculates comes the internal electric state of estimating battery.
2. device as claimed in claim 1, wherein
This charging device be configured to after the engine start of vehicle, carry out constant voltage charge and
This first calculation element, this decision maker, this harvester, this second calculation element and this estimation unit are configured to co-operation, so that estimate the internal electric state of this battery during the constant voltage charge that carries out immediately after the engine start.
3. device as claimed in claim 1, wherein
The moment that this charging device is configured to during vehicle ' is carried out constant voltage charge, this constantly charging current greater than set-point, and
This first calculation element, this decision maker, this harvester, this second calculation element and this estimation unit are configured to co-operation, so that the internal electric state of this moment estimating battery during vehicle '.
4. device as claimed in claim 1, wherein
The moment that this charging device is configured to during vehicle ' is carried out constant voltage charge, wherein this be positioned at constantly less than the charging current of set-point and discharging current continue after the state of a predetermined amount of time and
This first calculation element, this decision maker, this harvester, this second calculation element and this estimation unit are configured to co-operation, so that the internal electric state of this moment estimating battery during vehicle '.
5. device as claimed in claim 1, wherein
This first calculation element is configured to calculate polarization correlative P based on following formula:
Pn＝Pn-1+In*dt-1/T*Pn-1*dt，
The Pn currency of correlative P of representing to polarize wherein, Pn-1 represent the to polarize last time value of correlative P, In represents the currency of charging current, dt represents the sampling during the constant voltage charge and the time interval that keeps charging current, T express time constant.
6. device as claimed in claim 1, wherein
This second calculation element is configured to utilize the approximation formula of a large amount of charging current data computation charging current I that harvester gathers, and this calculating is based on:
I＝K+a*exp(b*t)，
Wherein a and b are constants, and t represents the elapsed time from constant voltage charge starting beginning institute, and K is given proportionality constant.
7. method that is used to estimate the internal electric state of in-vehicle secondary battery, the terminal voltage of regulating this in-vehicle secondary battery by alternating current generator in the operation car is a desired value, the method comprising the steps of:
Flow into the charging current of this battery and the discharging current that flows out from this battery with certain hour interval sampling and maintenance;
This battery is carried out constant voltage charge to predetermined value, this predetermined value after vehicle launch immediately or offer this battery during the vehicle ';
Utilize the charging current data in sampling and the maintenance step, the relevant polarization correlative of amount of polarization of calculating for the first time and after the constant voltage charge starting, in battery, causing immediately;
Whether the rate of change of judging the polarization correlative that calculates is lower than given threshold value;
When the rate of change of the polarization correlative that determines calculating is lower than this given threshold value, from sampling and maintenance step, be captured in the charging current data of sampling and keeping during the predetermined amount of time;
Utilize a large amount of charging current data, calculate the charging current value of when charging current reaches given final value, accumulating for the second time; And
Come the internal electric state of estimating battery based on the charging current accumulated value that calculates.
8. device that is used to estimate the internal electric state of in-vehicle secondary battery, the terminal voltage of regulating this in-vehicle secondary battery by alternating current generator in the operation car is a desired value, this device comprises:
Current detector, it detects charging current that flows into battery and the discharging current that flows out from battery;
Sampling apparatus, the electric current that it is detected by this current detector with certain hour interval sampling and maintenance;
Charging device, it carries out constant voltage charge to predetermined value to battery, this predetermined value after vehicle launch immediately or offer this battery during the vehicle ';
Calculation element, its a large amount of charging current data based on constant voltage charge starting post-sampling and maintenance are calculated the charging current function of the transient change of expression charging current;
Storage device, it stores corrected value relevant with cell degradation or correction function in advance;
Means for correcting, it proofreaies and correct this charging current function according to this corrected value or correction function;
Collecting apparatus, it accumulates charging current when charging current reaches given final value based on this calibrated charging current function; And
Estimation unit, it utilizes the accumulated value of charging current to estimate the internal electric state of this battery.
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| Application Number | Priority Date | Filing Date | Title |
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| JP2007301708A JP4564999B2 (en) | 2007-11-21 | 2007-11-21 | In-vehicle secondary battery internal state detection device |
| JP2007301648 | 2007-11-21 | ||
| JP2007-301708 | 2007-11-21 | ||
| JP2007301708 | 2007-11-21 | ||
| JP2007301648A JP4494454B2 (en) | 2007-11-21 | 2007-11-21 | In-vehicle secondary battery internal state detection device |
| JP2007-301648 | 2007-11-21 |
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| CN105467321A (en) * | 2014-05-29 | 2016-04-06 | 比亚迪股份有限公司 | Calculating method for residual charging time of battery, and battery system |
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| JP5081722B2 (en) * | 2008-05-26 | 2012-11-28 | 株式会社日本自動車部品総合研究所 | Charge control device for secondary battery |
| JP4962808B2 (en) * | 2009-02-24 | 2012-06-27 | 株式会社デンソー | Engine automatic control device and storage battery charge control device |
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| CN107728094A (en) * | 2017-10-23 | 2018-02-23 | 宁德时代新能源科技股份有限公司 | Current calibration coefficient measuring device and method, and current detecting device and method |
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Also Published As
| Publication number | Publication date |
|---|---|
| CN101447688B (en) | 2012-08-15 |
| JP2009126277A (en) | 2009-06-11 |
| JP4494454B2 (en) | 2010-06-30 |
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