CN104360285A - Battery capacity correction method based on improved ampere-hour integral method - Google Patents

Abstract

The invention discloses a battery capacity correction method based on an improved ampere-hour integral method. The method comprises the following steps: enabling a battery pack to run in a vehicle-mounted way; calculating the state of charge (SOC) by the ampere-hour integral method; judging whether the electric quantity of batteries is too low or not; judging whether the minimum battery voltage V<min> is lower than the threshold voltage V<mdy> in a capacity correction mode or not; entering the capacity correction mode; carrying out capacity correction, and then quitting the capacity correction mode; charging the batteries, and calculating the SOC; judging whether the maximum voltage V<max> of the battery pack is higher than charge cut-off voltage V<h> or not; finishing charging, storing the battery capacity Q accumulated in the charging process, and replacing the previous battery capacity Q<n> by the battery capacity Q; modifying the current battery capacity value to be Q, and modifying the value of the SOC. According to the method, the SOC values of the batteries and the stored electric quantity values are corrected at the end of the battery charging process, so that the accurate initial value of the SOC can be obtained after every time of charging is finished; furthermore, at the end of discharge, the batteries can select to enter the battery capacity correction mode, so that the current capacities of the batteries can be corrected, and thus the calculation error caused by battery aging can be eliminated.

Description

A kind of battery capacity modification method of the ampere-hour integral method based on improving

Technical field

The present invention relates to a kind of battery capacity modification method of the ampere-hour integral method based on improving.

Background technology

Battery dump energy also known as battery charge state (State of Charge, SOC) be represent that battery is current can one of the how many parameter of electricity that uses of electricity supply and use equipment, SOC can provide important evidence for the energy management strategies of electric automobile whole.Accurate estimating remaining capacity of battery can make SOC maintain in rational scope when battery uses, prevent the battery that overcharges or be excessively rivals in a contest and cause damage, be Appropriate application battery, extend battery, reduce battery use cost and provide important evidence.Accurate estimation SOC value is one of vital task of battery management system.

At present domestic and international to battery SOC estimation done large quantity research.Due to the hard-wired restriction of battery management system in actual product application, conventional method is the method that open-circuit voltage and ampere-hour integration combine, and also has Kalman filtering method and neural network in addition.

Kalman filtering, neural network: operand is large, and hardware is limited, and algorithm itself is immature, does not obtain a large amount of practical application.

Open-circuit voltage method: the method needs to leave standstill for a long time battery and needs the ocv curve of battery to have larger slope, but ferric phosphate lithium cell has more smooth charging and discharging curve, is not suitable for the soc estimation of ferric phosphate lithium cell in this way.

Ampere-hour integral method: the method is carried out to the integration of time to calculate the energy of input and output battery to electric current, by determining the value of soc with the ratio of rated capacity.The shortcoming of the method is, the determination of initial soc value accurately, otherwise must have very large error, and along with the prolongation of time, have larger cumulative errors, and there will be aging after battery uses the long period, the computational accuracy of ampere-hour integral method also can decline.

Chinese invention patent (the patent No.: 201410074003, patent name: the SOC on-line checkingi of lithium ion battery in charging process and modification method), this patent is by the SOC-V curve under the different discharge-rate of test and voltage difference, obtaining 3rd-SOC relation, by cell voltage, SOC being revised when calculating soc.But the impropriety of this method:

(1) discharge curve of lithium battery, particularly ferric phosphate lithium cell, the linearity is very poor, and the voltage difference of battery capacity between 90% to 20% only has 200mV, has higher requirements like this, and easily cause the error of calculation to voltage sample precision;

(2) the battery performance inconsistency of each producer is larger, and also larger change can be there is in same battery performance after a long time use, so just cause the test job that the needs during battery adapting to different manufacturers are a large amount of, and the problem that after can not solving cell degradation, soc computational accuracy reduces.

Chinese invention patent (patent No.: 201110165914X, patent name: remaining battery capacity and health status Forecasting Methodology), although be also correct cell degradation to the impact of power quantity predicting, there are two place's defects in this patent:

(1) method calculating aged battery capacity is the method determines the SOC value in formula by current battery level V1, current voltage V1 is not through the voltage after leaving standstill, and inapplicable sending out with open-circuit voltage determines SOC, so this computing method precision can receive impact;

(2) the open-circuit voltage method used in patent and ampere-hour integration are sent out the method combined and are applicable to the good lead-acid battery of voltage linear degree, but inapplicable and lithium battery.

Chinese invention patent (the patent No.: 2013107193759, patent name: a kind of self-correcting battery SOC evaluation method based on Kalman filtering), this patent can solve the problem that ampere-hour integral method can produce cumulative errors after long-play, but can not solve the impact that cell degradation causes volume change to calculate SOC.

Summary of the invention

Object of the present invention is exactly to solve the problem, a kind of battery capacity modification method of the ampere-hour integral method based on improving is provided, it has the shortcoming for ampere-hour integral method, the present invention carries out the latter stage of charging at battery, the SOC value of battery and the charge value of storage are corrected, make each charging complete can obtain SOC initial value accurately, battery discharge can be selected to enter battery capacity calibration pattern latter stage simultaneously, calibrate the capacity of present battery, thus eliminate the advantage of the error of calculation that cell degradation brings.

To achieve these goals, the present invention adopts following technical scheme:

Based on a battery capacity modification method for the ampere-hour integral method improved, comprise the steps:

Step (1): electric battery on-board running;

Step (2): the monomer battery voltage V of Real-time Obtaining electric battery _i, the highest cell voltage V _max, minimum cell voltage V _min, charging and discharging currents I; Ampere-hour integral method is utilized to calculate SOC;

Step (3): judge that whether battery electric quantity is too low, if just enter step (4); Just return step (2) if not;

Step (4): judge minimum cell voltage V _minwhether lower than cubage correction pattern threshold voltage V _mdy, if just enter step (5); Just enter step (6) if not;

Step (5): enter cubage correction pattern; Carry out cubage correction, then exit cubage correction pattern; Enter step (7);

Step (6): battery charges, calculates SOC; Enter step (7);

Step (7): judge electric battery ceiling voltage V _maxwhether be greater than charge cutoff voltage V _hif be greater than and just enter step (8); Otherwise return step (6);

Step (8): charging terminates, preserves the battery capacity Q of this charging process accumulation, and the battery capacity Q before substituting _n, revise current battery capacity value is Q simultaneously, amendment SOC value.

The step of described step (5) comprising:

Step (5-1): enter cubage correction pattern; Empty battery capacity and calculate variable;

Step (5-2): battery charges, and carries out the integral and calculating of SOC;

Step (5-3): judge whether to meet cubage correction condition, if just enter step (5-4); Just enter step (5-6) if not;

Step (5-4): judge electric battery ceiling voltage V _maxwhether be greater than charge cutoff voltage V _hif be greater than and just enter step (5-5); Otherwise return step (5-2);

Step (5-5): battery charging terminates, amendment SOC value, amendment battery capacity Q _n; Enter step (1);

Step (5-6): exit cubage correction pattern, enters step (7).

Described cubage correction pattern refers to the state manually entering or automatically capture, and carries out step (5) operation, occur discharge condition or V in this state _max>V _htime, automatically exit this pattern.

The formula carrying out the integral and calculating of SOC in described step (5-2) is:

$\mathrm{SOC}={\mathrm{SOC}}_0+\frac{1}{Q}{\&Integral;}_0^t\mathrm{Idt}$

Wherein, the meaning of parameters of SOC is present battery SOC value, SOC ₀meaning of parameters be initial SOC value, the meaning of parameters of t is the time, accumulation battery capacity temporary variable Q.

Beneficial effect of the present invention:

1. the present invention carries out latter stage of charging at battery, the SOC value of battery and the charge value of storage are corrected, make each charging complete can obtain SOC initial value accurately, battery discharge can be selected to enter battery capacity calibration pattern latter stage simultaneously, calibrate the capacity of present battery, thus eliminate the advantage of the error of calculation that cell degradation brings.

2 the present invention, for solving electric bus, are changing under power mode application, the raising of ferric phosphate lithium cell group SOC computational accuracy;

3 are easy to realize, and make full use of calibration and correction that the operation characteristic changing power mode electric bus carries out ampere-hour integral method, improve the precision of SOC estimation;

Initial SOC value demarcation is carried out in 4 each battery charging and discharging circulations, eliminates the cumulative errors in a circulation, can not produce long cumulative errors;

5 can revise the capacity of present battery from the health status of motion tracking battery, by revising the denominator in ampere-hour integral method formula, eliminate the error of calculation that cell degradation brings.

6. the inventive method also can avoid the generation of cumulative errors, and is easier to Project Realization.

7. calculate in units of a charge and discharge cycles and calibration battery energy value and soc value, avoid producing long error accumulation

8. automatic battery calculation of capacity, and soc computing formula is revised, eliminate the error of calculation that cell degradation brings.

Accompanying drawing explanation

Fig. 1 is method flow diagram of the present invention.

Embodiment

Below in conjunction with accompanying drawing and embodiment, the invention will be further described.

As shown in Figure 1, a kind of battery capacity modification method of the ampere-hour integral method based on improving, comprises the steps:

Step (1): electric battery on-board running;

Step (2): the monomer battery voltage V of Real-time Obtaining electric battery _i, the highest cell voltage V _max, minimum cell voltage V _min, charging and discharging currents I; Ampere-hour integral method is utilized to calculate SOC;

Step (3): judge that whether battery electric quantity is too low, if just enter step (4); Just return step (2) if not;

Step (4): judge minimum cell voltage V _minwhether lower than cubage correction pattern threshold voltage V _mdy, if just enter step (5); Just enter step (6) if not;

Step (5): enter cubage correction pattern; Carry out cubage correction, then exit cubage correction pattern; Enter step (7);

Step (6): battery charges, calculates SOC; Enter step (7);

Step (7): judge electric battery ceiling voltage V _maxwhether be greater than charge cutoff voltage V _hif be greater than and just enter step (8); Otherwise return step (6);

Step (8): charging terminates, preserves the battery capacity Q of this charging process accumulation, and the battery capacity Q before substituting _n, revise current battery capacity value is Q simultaneously, amendment SOC value.

The step of described step (5) comprising:

Step (5-1): enter cubage correction pattern; Empty battery capacity and calculate variable;

Step (5-2): battery charges, carry out the integral and calculating of SOC; Wherein the meaning of parameters of SOC is present battery SOC value, SOC ₀meaning of parameters be initial SOC value, the meaning of parameters of t is the time, accumulation battery capacity temporary variable Q;

Step (5-3): judge whether to meet cubage correction condition, if just enter step (5-4); Just enter step (5-6) if not;

Step (5-4): judge electric battery ceiling voltage V _maxwhether be greater than charge cutoff voltage V _hif be greater than and just enter step (5-5); Otherwise return step (5-2);

Step (5-5): battery charging terminates, amendment SOC value, amendment battery capacity Q _n; Enter step (1);

Step (5-6): exit cubage correction pattern, enters step (7).

Described cubage correction pattern refers to the state manually entering or automatically capture, and carries out step (5) operation, occur discharge condition or V in this state _max>V _htime, automatically exit this pattern.

By reference to the accompanying drawings the specific embodiment of the present invention is described although above-mentioned; but not limiting the scope of the invention; one of ordinary skill in the art should be understood that; on the basis of technical scheme of the present invention, those skilled in the art do not need to pay various amendment or distortion that creative work can make still within protection scope of the present invention.

Claims (4)

1., based on a battery capacity modification method for the ampere-hour integral method improved, it is characterized in that, comprise the steps:

Step (1): electric battery on-board running;

Step (2): the monomer battery voltage V of Real-time Obtaining electric battery _i, the highest cell voltage V _max, minimum cell voltage V _min, charging and discharging currents I; Ampere-hour integral method is utilized to calculate SOC;

Step (3): judge that whether battery electric quantity is too low, if just enter step (4); Just return step (2) if not;

Step (4): judge minimum cell voltage V _minwhether lower than cubage correction pattern threshold voltage V _mdy, if just enter step (5); Just enter step (6) if not;

Step (5): enter cubage correction pattern; Carry out cubage correction, then exit cubage correction pattern; Enter step (7);

Step (6): battery charges, calculates SOC; Enter step (7);

Step (7): judge electric battery ceiling voltage V _maxwhether be greater than charge cutoff voltage V _hif be greater than and just enter step (8); Otherwise return step (6);

Step (8): charging terminates, preserves the battery capacity Q of this charging process accumulation, and the battery capacity Q before substituting _n, revise current battery capacity value is Q simultaneously, amendment SOC value.

2. a kind of battery capacity modification method of ampere-hour integral method based on improving as claimed in claim 1, it is characterized in that, the step of described step (5) comprising:

Step (5-1): enter cubage correction pattern; Empty battery capacity and calculate variable;

Step (5-2): battery charges, and carries out the integral and calculating of SOC;

Step (5-3): judge whether to meet cubage correction condition, if just enter step (5-4); Just enter step (5-6) if not;

Step (5-4): judge electric battery ceiling voltage V _maxwhether be greater than charge cutoff voltage V _hif be greater than and just enter step (5-5); Otherwise return step (5-2);

Step (5-5): battery charging terminates, amendment SOC value, amendment battery capacity Q _n; Enter step (1);

Step (5-6): exit cubage correction pattern, enters step (7).

3. a kind of battery capacity modification method of ampere-hour integral method based on improving as claimed in claim 1, it is characterized in that, described cubage correction pattern refers to the state manually entering or automatically capture, in this state, carry out step (5) operation, occur discharge condition or V _max>V _htime, automatically exit this pattern.

4. a kind of battery capacity modification method of ampere-hour integral method based on improving as claimed in claim 1, it is characterized in that, the formula carrying out the integral and calculating of SOC in described step (5-2) is:

$\mathrm{SOC}={\mathrm{SOC}}_0+\frac{1}{Q}{\&Integral;}_0^t\mathrm{Idt}$

Wherein, the meaning of parameters of SOC is present battery SOC value, SOC ₀meaning of parameters be initial SOC value, the meaning of parameters of t is the time, accumulation battery capacity temporary variable Q.