CN105607010A - Method for estimating health state of power battery of electric vehicle - Google Patents

Abstract

The invention relates to the field of estimation of a state of a power battery of an electric vehicle, especially relates to a method for estimating a health state of a power battery of an electric vehicle, and brings forward a method for estimating a health state of a power battery of an electric vehicle, for solving the problems of low estimation precision, instability, long consumed time, large workload, high estimation cost and too high reliance of an estimation result on the corresponding relation between the charge state and the open-circuit voltages of a power battery and the accuracy of an equivalent circuit model during estimation of the health state of the power battery in the prior art. Atual measurement end voltages V0 and charge and discharge currents I of the power battery, open-circuit voltages V<100%SoC> of the power battery at an electric quantity full-charge state and open-circuit voltages V<0%SoC> at an electric quantity full-discharge state are acquired; an equivalent circuit model of the power battery is established, and an simulated value C<b><^> of a storage capacitor C<b> of the power battery is identified; and an estimated value C<cap><^> of a maximum available capacity C<cap> of the power battery is estimated according to an expression shown in the descriptions. The method provided by the invention is simple in calculation, small in calculation amount, high in precision and high in adaptability.

Description

A kind of method of health status of the electrokinetic cell of estimating electric vehicle

Technical field

The present invention relates to electric vehicle vehicle mounted dynamic battery state estimation field, relate in particular to a kind of moving electric vehicleThe method that the health status of power battery is estimated.

Background technology

The health status (StateofHealth is called for short SOH) of electric vehicle vehicle mounted dynamic battery is to evaluate this power electricThe important indicator of the current performance in pond. In the ageing process of electrokinetic cell, the health status major embodiment of electrokinetic cell is for movingThe decay of the maximum available of power battery and the increase of internal resistance. And the aging impact that is subject to factors of electrokinetic cell, such asThe factors such as temperature, charge-discharge magnification and depth of discharge, cause the maximum available of electrokinetic cell and the variation of internal resistance to have the utmost pointLarge uncertainty and non-linear, and then (batterymanagementsystem is called for short to give power battery management systemBMS) in management process, the maximum available to electrokinetic cell and internal resistance detect and bring huge challenge.

In addition, when electrokinetic cell uses in groups, by experiment means directly obtain electrokinetic cell capacity information andInternal resistance information, and the maximum available of electrokinetic cell directly affects the state-of-charge (Stateof of electrokinetic cellCharge, is called for short SOC) estimated value, and the estimated accuracy of the state-of-charge of electrokinetic cell is directly connected to making of electrokinetic cellThe safety with whether, therefore, is the safe handling that ensures electrokinetic cell, and power battery management system must be to the maximum of electrokinetic cellActive volume is accurately estimated, the health status of electrokinetic cell is accurately estimated.

The maximum available of electrokinetic cell refers under a certain specified temp and degree of aging, and electrokinetic cell is according to markClaim to be filled with when multiplying power is filled (putting) electric blanking voltage to this electrokinetic cell the electric weight of (emitting). Because electrokinetic cell is fillingDifference between maximum available when electricity and the maximum available in the time of electric discharge is less than 1%, therefore, conventionally gets the twoMean value is the maximum available under current state as electrokinetic cell.

At present, the method for the maximum available of electrokinetic cell being estimated can be divided into following four kinds substantially:

1, the method that the open-circuit voltage based on electrokinetic cell is estimated the maximum available of electrokinetic cell, according to movingThe unique monotone variation relation existing between the state-of-charge of power battery and its open-circuit voltage is utilized the open circuit electricity of electrokinetic cellPressure estimates the state-of-charge of this electrokinetic cell, and is considering under the prerequisite that electrokinetic cell is aging the state-of-charge of electrokinetic cellRefer to the dump energy of electrokinetic cell and the percentage of its maximum available under current state, and then by recordingThe dump energy of electrokinetic cell and state-of-charge estimate the maximum available of electrokinetic cell under current state.

2, the method that the equivalent-circuit model based on electrokinetic cell is estimated the maximum available of electrokinetic cell, logicalThe equivalent-circuit model of crossing electrokinetic cell constructs the dynamical equation of this electrokinetic cell, and by available the maximum of this electrokinetic cell appearanceAmount is estimated as unknown state.

3, the side based on capacity gain analysis and power supply differential analysis, the maximum available of electrokinetic cell being estimatedMethod, the chemical reaction degree to electrokinetic cell inside under laboratory environment that lays particular emphasis on is described.

4, the aging method that its maximum available is estimated based on electrokinetic cell is mainly data by experimentAnalyze the impact of the decline of the maximum available of different aging actions on electrokinetic cell, thereby set up the capacity of electrokinetic cellDegenerated mode or remaining life model are estimated the maximum available of electrokinetic cell.

Above-mentioned four kinds of methods of estimation can be divided into off-line to be estimated and On-line Estimation two classes, wherein, adopts off-line method of estimation pairWhen the maximum available of electrokinetic cell is estimated, if adopt less statistics to analyze, may cause again estimatingDeviation is larger, and estimated accuracy is low and unstable, if adopt a large amount of statistics to analyze, although can meet estimated accuracyRequirement, still, data accumulation length consuming time and data analysis workload are large. Employing On-line Estimation method can to the maximum of electrokinetic cellWhile estimation with capacity, can estimate in real time and ensure estimated accuracy, still, On-line Estimation is to electrokinetic cell management systemThe computing capability of system requires very high, causes estimated cost higher, and estimated result is to the state-of-charge of electrokinetic cell and open circuit electricityThe accuracy of the corresponding relation between pressure and the equivalent-circuit model of electrokinetic cell has very strong dependence.

Summary of the invention

Be that maximum available is estimated time or estimation for solving in prior art to the health status of electrokinetic cellPrecision is low and unstable, otherwise length consuming time and workload large, or required because of the computing capability to power battery management systemHeight causes the high and estimated result of estimated cost to the corresponding relation between the state-of-charge-open-circuit voltage of electrokinetic cell and equivalenceThe accuracy of circuit model relied on strong problem, and the present invention proposes a kind of health status of the electrokinetic cell of estimating electric vehicleMethod, the method comprises the steps:

Step 1, in described electrokinetic cell charge and discharge process, to the actual measurement terminal voltage V of described electrokinetic cell₀With discharge and rechargeElectric current I is sampled, and sampling time interval is Δ t, and gathers described electrokinetic cell and be full of the open circuit under electricity condition at electric weightVoltage V_100％SoCThe open-circuit voltage V giving out light under electricity condition with electric weight_0％SoC；

Step 2, select the equivalent-circuit model of RC model as described electrokinetic cell, and the charging and discharging currents I collectingWhile being input in described RC model, the actual measurement terminal voltage V collecting₀For the output of described RC model, identification draws described powerAccumulate capacitor C in the equivalent-circuit model of battery_bEstimated value

Step 3, utilize accumulate capacitor C in the equivalent circuit of described electrokinetic cell_bEstimated valueAccording toEstimate to draw the maximum available C of described electrokinetic cell_capEstimated value

When the inventive method is carried out off-line estimation to the maximum available of electrokinetic cell, draw electrokinetic cell by samplingActual measurement terminal voltage and charging and discharging currents, and the charging and discharging currents in sampled data is input to electrokinetic cell RC model beIn system equation, utilize optimized algorithm to pick out the model parameter of the RC model of electrokinetic cell, and then estimate the power that identification drawsThe accumulate capacitor C of battery_bEstimated valueAnd corresponding one by one between the accumulate electric capacity of electrokinetic cell and maximum availableRelation estimates the maximum available C of electrokinetic cell_capEstimated valueCalculate simply, amount of calculation is little, and estimated accuracyHigher; Can estimate the maximum available of the electrokinetic cell under different degree of agings, and ensure estimated accuracy, applicabilityBy force.

Preferably, in described step 1, sampling time interval Δ t is definite value, so that image data. Further, instituteStating described sampling time interval Δ t is 1s.

Preferably, the system equation of the RC model of described electrokinetic cell is:

$\left\{\begin{array}{c}{V}_0=\frac{R_e}{(R_s+R_e)}{V}_b+\frac{R_s}{(R_s+R_e)}{V}_s+\frac{(R_t{R}_s+R_t{R}_e+R_e{R}_s)}{(R_s+R_e)}I\\ {\stackrel{\&CenterDot;}{V}}_b=\frac{V_s}{C_b(R_s+R_e)}-\frac{V_b}{C_b(R_s+R_e)}+\frac{R_s}{C_b(R_s+R_e)}I\\ {\stackrel{\&CenterDot;}{V}}_s=\frac{V_b}{C_s(R_s+R_e)}-\frac{V_s}{C_s(R_s+R_e)}+\frac{R_e}{C_b(R_s+R_e)}I\end{array}\right.,$

Wherein,

R_eRepresent the terminating resistor of described electrokinetic cell,

R_tRepresent the Ohmic resistance of described electrokinetic cell,

V_bRepresent the voltage at the accumulate capacitor C b two ends of described electrokinetic cell,

R_sRepresent the polarization resistance of described electrokinetic cell,

V_sRepresent the polarizing voltage of described electrokinetic cell,

C_sRepresent the polarization capacity of described electrokinetic cell.

Preferably, adopt the model parameter of the equivalent-circuit model of genetic algorithm to described electrokinetic cell to carry out identification, andModel parameter ξ=[R to be identified_tR_sC_sR_eC_b]^T, wherein, T representing matrix transposition.

Preferably, in the time that the model parameter of the equivalent-circuit model to described electrokinetic cell carries out identification, target setting letterNumber $F=\min \left\{\underset{i=1}{\overset{N}{\&Sigma;}}{(V_{0,i}-{\hat{V}}_{0,i}(\mathrm{\&xi;}\left)\right)}^2\right\},$

Wherein,

N represents the length of sampled data,

V_0,iRepresent the actual measurement terminal voltage in i moment in described electrokinetic cell charge and discharge process,

Represent the estimation terminal voltage in i moment in described electrokinetic cell charge and discharge process,

Represent the estimated value of described model parameter ξ to be identified.

When the inventive method is carried out off-line estimation to the maximum available of electrokinetic cell, draw electrokinetic cell by samplingActual measurement terminal voltage and charging and discharging currents, and the charging and discharging currents in sampled data is input to electrokinetic cell RC model beIn system equation, utilize optimized algorithm to pick out the model parameter of the RC model of electrokinetic cell, and then estimate the power that identification drawsThe accumulate capacitor C of battery_bEstimated valueAnd corresponding one by one between the accumulate electric capacity of electrokinetic cell and maximum availableRelation estimates the maximum available C of electrokinetic cell_capEstimated valueCalculating is simple, amount of calculation is little and estimated accuracyHigher. Adopt RC model to portray the active volume of electrokinetic cell, there is uniqueness compared to RC equivalent-circuit model in parallelAdvantage. In the time that the maximum available of the electrokinetic cell of the degree of aging to different is estimated, all can be to electrokinetic cellMaximum available accurately estimate, applicability is strong.

The present invention also proposes a kind of side of health status of the electrokinetic cell that adopts above-mentioned any one estimation electric vehicleThe device that the health status of the electrokinetic cell of method to electric vehicle is estimated.

Brief description of the drawings

Fig. 1 is the flow chart that the present invention estimates the health status of the electrokinetic cell of electric vehicle;

Fig. 2 is the equivalent circuit diagram of the RC model of electrokinetic cell;

Fig. 3 is the equivalent circuit diagram of the RC equivalent-circuit model in parallel of electrokinetic cell;

Fig. 4 is the distribution map of the charging and discharging currents of the circulation electrokinetic cell of 0 time under DST operating mode;

Fig. 5 is the actual measurement terminal voltage time history plot of the electrokinetic cell shown in Fig. 4;

Fig. 6 is the estimation terminal voltage time history plot of the electrokinetic cell shown in Fig. 4;

Fig. 7 is the change curve of the evaluated error of the terminal voltage of the electrokinetic cell shown in Fig. 4;

Fig. 8 is the distribution map of the charging and discharging currents of the circulation electrokinetic cell of 200 times under DST operating mode;

Fig. 9 is the actual measurement terminal voltage time history plot of the electrokinetic cell shown in Fig. 8;

Figure 10 is the estimated value time history plot of the terminal voltage of the electrokinetic cell shown in Fig. 8;

Figure 11 is the change curve of the evaluated error of the terminal voltage of the electrokinetic cell shown in Fig. 8.

Detailed description of the invention

Estimate that in conjunction with Fig. 1-11 couple the present invention the method for the health status of the electrokinetic cell of electric vehicle carries out in detail below,Explanation.

Due to the decay of the health status main manifestations of the electrokinetic cell maximum available that is electrokinetic cell and internal resistanceIncrease, and when internal resistance increases, the corresponding reduction of the maximum available of electrokinetic cell, therefore the present invention only passes through electrokinetic cellMaximum available estimates the health status of electrokinetic cell to estimate.

As shown in Figure 1, electrokinetic cell is discharged and recharged to test, and in process of the test, gather the actual measurement end of electrokinetic cellVoltage (measured value of terminal voltage) and charging and discharging currents, and electrokinetic cell is full of the open-circuit voltage under electricity condition at electric weightV_100％SoCThe open-circuit voltage V giving out light under electricity condition with electric weight_0％SoC; Set up the equivalent-circuit model of this electrokinetic cell, and according to instituteThe equivalent-circuit model of setting up sets up the system equation of electrokinetic cell, and the charging and discharging currents collecting is input to electrokinetic cellIn system equation, and pick out the model parameter of the equivalent-circuit model of electrokinetic cell according to the requirement of object function, and then estimateCalculate the maximum available of electrokinetic cell under current state, thereby estimate the health status of electrokinetic cell.

Concrete steps are as follows:

Step 1, actual measurement terminal voltage V0 and charging and discharging currents I and the power electric of collection electrokinetic cell in charge and discharge processThe open-circuit voltage in pond

At the same temperature, electrokinetic cell is discharged and recharged to test, and in charge and discharge process the reality to electrokinetic cellSurvey terminal voltage V₀I samples with charging and discharging currents, and sampling time interval is between the time between adjacent two sampling instantsBe divided into Δ t, such as, the time interval between i moment and i+1 moment is a sampling time interval Δ t, and gathers powerBattery is full of the open-circuit voltage V under electricity condition at electric weight_100％SoCThe open-circuit voltage V giving out light under electricity condition with electric weight_0％SoC. PreferablyGround, sampling time interval Δ t was definite value, such as 1 second (s).

Step 2, set up the equivalent-circuit model of electrokinetic cell, and pick out the model parameter of this equivalent-circuit model

Portraying aspect the active volume of electrokinetic cell, due to equivalent circuit diagram RC model as shown in Figure 2 with respect to asRC equivalent-circuit model in parallel shown in Fig. 3 has unique advantage, therefore select the equivalent circuit of RC model as electrokinetic cellModel. Wherein, the accumulate capacitor C in equivalent circuit_bBe used for representing the ability of electrokinetic cell storing electricity, and this accumulate capacitor C_bCan with the maximum available C of electrokinetic cell_capSet up one-to-one relationship; Ohmic internal resistance R_tRepresent electrode in electrokinetic cellThe contact resistance of material, electrolyte, barrier film resistance and other parts; R_eRepresent the terminating resistor of electrokinetic cell; R_sRepresent power electricThe polarization resistance in pond; V_sRepresent the polarizing voltage of electrokinetic cell, C_sRepresent the polarity effect of electrokinetic cell. Fixed according to kirchhoffLv Ke get:

$\left\{\begin{array}{c}{V}_0={\mathrm{IR}}_t+I_b{R}_e+V_b\\ V_0={\mathrm{IR}}_t+I_s{R}_s+V_s\\ I_b=C_b{\stackrel{\&CenterDot;}{V}}_b\\ I_s=C_s{\stackrel{\&CenterDot;}{V}}_s\end{array}\right.$

Wherein,

I_bBe illustrated in charge and discharge process medium power battery by terminating resistor R_eWith accumulate capacitor C_bThe accumulate that series connection forms props upElectric current on road,

V_bRepresent the accumulate capacitor C of electrokinetic cell_bThe voltage at two ends, i.e. the accumulate voltage of electrokinetic cell,

I_sBe illustrated in charge and discharge process medium power battery by polarization resistance R_sWith polarization capacity C_sThe polarization that series connection forms is propped upElectric current on road.

And then can draw the system equation of electrokinetic cell, this system equation comprises the measurement equation of electrokinetic cell:

$V_0=\frac{R_e}{(R_s+R_e)}{V}_b+\frac{R_s}{(R_s+R_e)}{V}_s+\frac{(R_t{R}_s+R_t{R}_e+R_e{R}_s)}{(R_s+R_e)}I$

Dynamical equation:

$\{\begin{array}{c}{\stackrel{\&CenterDot;}{V}}_b=\frac{V_s}{C_b(R_s+R_e)}-\frac{V_b}{C_b(R_s+R_e)}+\frac{R_s}{C_b(R_s+R_e)}I\\ {\stackrel{\&CenterDot;}{V}}_s=\frac{V_b}{C_s(R_s+R_e)}-\frac{V_s}{C_s(R_s+R_e)}+\frac{R_e}{C_b(R_s+R_e)}I\end{array}.$

The charging and discharging currents I of the electrokinetic cell that sampling is obtained and actual measurement terminal voltage V₀As the equivalent circuit of electrokinetic cellThe system input of model and system are exported, and by optimized algorithm such as Identification of Genetic Algorithm goes out the equivalent circuit mould of electrokinetic cellThe model parameter ξ=[R of type_tR_sC_sR_eC_b]^T. In the model ginseng of the equivalent-circuit model that adopts genetic algorithm to electrokinetic cellAmount ξ=[R_tR_sC_sR_eC_b]^TWhile carrying out identification, first, the electrokinetic cell that sampling is obtained is at the charging and discharging currents Ii in i momentBe input in the dynamical equation of electrokinetic cell, draw the polarizing voltage estimated value of this electrokinetic cell in the i momentWith accumulate electricityPress estimated valueAnd then draw the estimation terminal voltage of electrokinetic cell in the i momentWith voltage estimate vector ${\hat{U}}_i={\left[\begin{array}{cc}{\hat{V}}_{s,i}& {\hat{V}}_{b,i}\end{array}\right]}^T,$ Wherein, T representing matrix transposition; Then, the dynamical equation of electrokinetic cell draws voltage estimate vectorChange amountAnd then show that next moment is i+1 moment voltage estimate vectorThen, by the electricity in i+1 momentPress estimate vectorBe brought in the RC model of electrokinetic cell, estimate terminal voltage the estimating in the i+1 moment of this electrokinetic cellEvaluationAnd judge whether i >=N sets up, and in the time that i >=N is false, the actual measurement of the electrokinetic cell that continuation utilization sampling obtainsTerminal voltage and charging and discharging currents are estimated the terminal voltage of electrokinetic cell and are obtained estimated value, until i >=N sets up; Then, rootThe electrokinetic cell obtaining according to employing is at the actual measurement terminal voltage V in i moment_0,iWith estimation terminal voltageCalculate the end of electrokinetic cellThe quadratic sum of the evaluated error of voltageAndFinally, target setting function F makesThe quadratic sum minimum of the evaluated error of the terminal voltage of battery,OrThereby pick out the estimated value of the model parameter of the RC model of electrokinetic cellAnd then draw power electricThe accumulate capacitor C in pond_bEstimated value

Step 3, due to the accumulate capacitor C of electrokinetic cell_bMaximum available C with this electrokinetic cell_capBetween have oneOne corresponding relation, $C_b=\frac{2\&times;C_{cap}\&times;V_{100\%SoC}}{(V_{100\%SoC}^2-V_{0\%SoC}^2)}.$

Therefore, picking out the accumulate capacitor C of electrokinetic cell_bEstimated valueAfter, can pass through the accumulate electric capacity of electrokinetic cellC_bWith maximum available C_capBetween one-to-one relationship estimation draw the maximum available C of electrokinetic cell_capEstimationValue

Below, taking nominal capacity as 25Ah, nominal voltage be the lithium ion battery of 3.7 volts (V) as subjects, testCard the present invention exist in the time that the maximum available of estimating the electrokinetic cell on electric vehicle is the health status of electrokinetic cellAdvantage. Respectively taking degree of aging as circulation 0 time and the circulation electrokinetic cell of 200 times as example, illustrate and adopts the inventive method to movingThe estimation effect when maximum available of power battery is estimated.

Eg1, degree of aging are the circulation electrokinetic cell of 0 time

First, this electrokinetic cell is carried out to ambulatory stress test (DynamicStressTest is called for short DST), and environmentTemperature is 10 DEG C, and the actual measurement terminal voltage V0 to this electrokinetic cell and charging and discharging currents I sample in test process, and adoptsSample time interval Δ t is 1s, gathers electrokinetic cell and is full of the open-circuit voltage V under electricity condition at electric weight_100％SoCWith the electric weight electricity of giving out lightOpen-circuit voltage V under state_0％SoC. Record by experiment this electrokinetic cell maximum available be 25.75Ah. This powerBattery in circulation the essential information 0 time time as shown in table 1; The charging and discharging currents I of this electrokinetic cell that sampling draws becomes in timeThe curve of changing as shown in Figure 4, is surveyed terminal voltage V₀Time dependent curve as shown in Figure 5.

Table 1

	Maximum available (Ah)	V100％SoC(V)	V0％SoC(V)
				Circulate 0 time	25.75	4.1298	3.3678

Utilize Identification of Genetic Algorithm to draw the model parameter ξ=[R of the RC model of electrokinetic cell_tR_sC_sR_eC_b]^TAs table 2Shown in, the estimation terminal voltage of the electrokinetic cell that estimation drawsTime dependent curve as shown in Figure 6, and is estimated to drawThe time dependent curve of evaluated error of the terminal voltage of electrokinetic cell as shown in Figure 7, and then draws the accumulate electricity of electrokinetic cellHold C_bEstimated valueThereby according to the accumulate capacitor C of this electrokinetic cell_bWith maximum available C_capBetween corresponding one by oneRelation estimation draws this electrokinetic cell maximum available C_capEstimated valueFor 25.7620Ah.

Table 2

The method of the health status of the electrokinetic cell of the battery electric vehicle that as can be seen here, employing the present invention proposes is to circulationWhen the maximum available of the electrokinetic cell of 0 time is estimated, evaluated error is only 0.0466%, and estimated accuracy is high.

Eg2, degree of aging are the circulation electrokinetic cell of 200 times

First, be at 10 DEG C in environment temperature, this electrokinetic cell is carried out to ambulatory stress test, and to this electrokinetic cellActual measurement terminal voltage V₀I samples with charging and discharging currents, and sampling time interval Δ t is definite value, gathers electrokinetic cell at electric weightBe full of the open-circuit voltage V under electricity condition_100％SoCThe open-circuit voltage V giving out light under electricity condition with electric weight_0％SoC. Record by experiment thisElectrokinetic cell maximum available be 24.58Ah. This electrokinetic cell in circulation the essential information 200 times time as shown in table 3;The time dependent curve of charging and discharging currents I of this electrokinetic cell that sampling draws as shown in Figure 8, is surveyed terminal voltage V₀In timeThe curve changing as shown in Figure 9.

Table 3

	Maximum available (Ah)	V100％SoC(V)	V0％SoC(V)
				Circulate 200 times	24.58	4.1298	3.3678

Utilize Identification of Genetic Algorithm to draw the model parameter ξ=[R of the RC model of electrokinetic cell_tR_sC_sR_eC_b]^TAs table 4Shown in, the estimation terminal voltage of the electrokinetic cell that estimation drawsTime dependent curve as shown in figure 10, and is estimated to drawThe time dependent curve of evaluated error of the terminal voltage of electrokinetic cell as shown in figure 11, and then draws the accumulate electricity of electrokinetic cellHold C_bEstimated valueThereby according to accumulate capacitor C_bWith maximum available C_capBetween one-to-one relationship estimation drawElectrokinetic cell maximum available C_capEstimated valueFor 24.3584Ah.

Table 4

The method of the health status of the electrokinetic cell of the battery electric vehicle that as can be seen here, employing the present invention proposes is to circulationWhen the maximum available of the electrokinetic cell of 200 times is estimated, evaluated error is-0.9014%, and estimated accuracy is high.

The method of the health status of the electrokinetic cell of the estimation electric vehicle that as fully visible, employing the present invention proposes is to powerWhen the maximum available of battery is estimated, estimate accurately, and at the electrokinetic cell under different degree of agingsWhen large active volume is estimated, all can accurately estimate the maximum available of electrokinetic cell, applicability is strong.

Claims (7)

1. a method of estimating the health status of the electrokinetic cell of electric vehicle, is characterized in that, the method comprises following stepRapid:

Step 1, in described electrokinetic cell charge and discharge process, to the actual measurement terminal voltage V of described electrokinetic cell₀With charging and discharging currents ISample, and sampling time interval is Δ t, and gathers described electrokinetic cell and be full of the open-circuit voltage under electricity condition at electric weightV_100％SoCThe open-circuit voltage V giving out light under electricity condition with electric weight_0％SoC；

Step 2, select the equivalent-circuit model of RC model as described electrokinetic cell, and the charging and discharging currents I collecting inputTo in described RC model time, the actual measurement terminal voltage V collecting₀For the output of described RC model, identification draws described electrokinetic cellEquivalent-circuit model in accumulate capacitor C_bEstimated value

Step 3, utilize accumulate capacitor C in the equivalent circuit of described electrokinetic cell_bEstimated valueAccording toEstimate to draw the maximum available C of described electrokinetic cell_capEstimated value

2. the method for the health status of the electrokinetic cell of estimation electric vehicle according to claim 1, is characterized in that,In described step 1, sampling time interval Δ t is definite value.

3. the method for the health status of the electrokinetic cell of estimation electric vehicle according to claim 2, is characterized in that, instituteStating sampling time interval Δ t is 1s.

4. according to the method for the health status of the electrokinetic cell of the estimation electric vehicle described in any one in claim 1-3,It is characterized in that, the system equation of the RC model of described electrokinetic cell is:

$\left\{\begin{array}{c}{V}_0=\frac{R_e}{(R_s+R_e)}{V}_b+\frac{R_s}{(R_s+R_e)}{V}_s+\frac{(R_t{R}_s+R_t{R}_e+R_e{R}_s)}{(R_s+R_e)}I\\ {\stackrel{\&CenterDot;}{V}}_b=\frac{V_s}{C_b(R_s+R_e)}-\frac{V_b}{C_b(R_s+R_e)}+\frac{R_s}{C_b(R_s+R_e)}I\\ {\stackrel{\&CenterDot;}{V}}_s=\frac{V_b}{C_s(R_s+R_e)}-\frac{V_s}{C_s(R_s+R_e)}+\frac{R_e}{C_b(R_s+R_e)}I\end{array}\right.,$

Wherein,

R_eRepresent the terminating resistor of described electrokinetic cell,

R_tRepresent the Ohmic resistance of described electrokinetic cell,

V_bRepresent the accumulate capacitor C of described electrokinetic cell_bThe voltage at two ends,

R_sRepresent the polarization resistance of described electrokinetic cell,

V_sRepresent the polarizing voltage of described electrokinetic cell,

C_sRepresent the polarization capacity of described electrokinetic cell.

5. the method for the health status of the electrokinetic cell of estimation electric vehicle according to claim 4, is characterized in that, adoptsThe model parameter of the equivalent-circuit model by genetic algorithm to described electrokinetic cell carries out identification, and model parameter ξ to be identified＝[R_tR_sC_sR_eC_b]^T, wherein, T representing matrix transposition.

6. the method for the health status of the electrokinetic cell of estimation electric vehicle according to claim 5, is characterized in that,When the model parameter of the equivalent-circuit model to described electrokinetic cell carries out identification, target setting function $F=\min \left\{\underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}{(V_{0,i}-{\hat{V}}_{0,i}(\widehat{\mathrm{\&xi;}}\left)\right)}^2\right\},$

Wherein,

N represents the length of sampled data,

V_0,iRepresent the actual measurement terminal voltage in i moment in described electrokinetic cell charge and discharge process,

Represent the estimation terminal voltage in i moment in described electrokinetic cell charge and discharge process,

Represent the estimated value of described model parameter ξ to be identified.

7. one kind adopts the side of the health status of the electrokinetic cell of the estimation electric vehicle described in any one in claim 1-6The device that the health status of the electrokinetic cell of method to electric vehicle is estimated.