CN101324656B - Method for predicting battery charge electricity - Google Patents

Abstract

The invention relates to a battery charge forecasting method and a device which can effectively forecast the battery charge state of a vehicle. The invention has two technical proposals based on the same invention concept: 1. the battery charge forecasting method is characterized in that the charge and the discharge between a high voltage battery and an inverter of the whole vehicle part are carried out through a high-voltage wire, and a main controller obtains the current charge state according to the charge and the discharge current signals, the battery temperature signal and the battery voltage signal. 2. The battery charge forecasting device for realizing the method is characterized in that the device is provided with a battery current sensor and a battery temperature sensor; the current sensor and the temperature sensor are respectively connected with a current detection loop and a temperature detection loop; the device is simultaneously provided with a battery voltage detection loop; single output ends of the temperature detection loop, the current detection loop and the voltage detection loop are connected with an A/D converter; and the single output end of the A/D converter is connected with the main controller.

Description

A kind of battery charge Forecasting Methodology

Technical field

The present invention relates to the charged Forecasting Methodology of a kind of automobile batteries.

Background technology

Battery is as a kind of electrochmical power source, and itself and physical power source have difference in essence.Because the work characteristics of electrochmical power source nonrepeatability, therefore need consideration factor in many ways, as: external environment condition (as environment temperature), operating parameter (charging and discharging currents discharges and recharges the time), self character (characteristic of all kinds battery) could carry out a prediction more accurately to battery charge state.

At present, the use of electrochmical power source in the field of mobile phone, notebook computer, various electric tools is very general, also comparatively simple and ripe to its state-of-charge Study on Forecast and application, record is also all arranged in various documents, introduced a kind of cell voltage margin of cell phone display packing and device as the CN200510007491.3 patent, the CN00136839.7 patent has been introduced a kind of measure and control device and investigating method of battery capacity for notebook computer.

In recent years, because automobile main frame maker is to the competitively exploitation of various electric automobiles, very big challenge has also been proposed to the state-of-charge Forecasting Methodology of used battery on the electric automobile.Battery charge state prediction in the past is many to be realized by the computing of surplus meter.Under certain simple environment for use, as: charging and discharging currents changes little, and when environment temperature was stablized, this method can obtain result preferably.If battery is used in the electric motor car, especially be used in the PHEV, the charging and discharging currents value changes in a very big scope, and serviceability temperature also changes bigger, if still use above-mentioned easy method, do not reach the accuracy value of expection at all, not only can not optimize the performance of car load, and might finally cause cell damage serious even scrap.

Summary of the invention

Goal of the invention of the present invention is to provide a kind of battery charge Forecasting Methodology, can effectively predict the automobile batteries state-of-charge.

Realize the technical scheme of the object of the invention:

A kind of battery charge Forecasting Methodology, it is characterized in that: discharge and recharge by hi-line between the inverter of high-tension battery and car load part, master controller calculates according to charging and discharging currents signal, battery temperature signal and battery voltage signal and obtains current state-of-charge; The computing formula of current state-of-charge is: $\mathrm{SOC}={\mathrm{SOC}}_0+\∫\frac{I*t}{\mathrm{Cn}*\mathrm{\β}}\mathrm{\η},$ Wherein SOC is current charged value, SOC ₀Be the charged value before powering on, Cn is the rated capacity of battery, and η is an efficiency for charge-discharge, and β is the cell degradation coefficient, and integration variable is time t.

The beneficial effect that the present invention has:

The present invention can predict the state-of-charge of hybrid vehicle battery accurately and effectively, can not only better satisfy the demand of car load, but also can make battery be in top condition, prolongs battery serviceable life.

Description of drawings

Fig. 1 is the electric principle of compositionality figure of the present invention;

Fig. 2 is the self-discharge of battery curve map;

The curve map that battery open circuit voltage changed with SOC, T when Fig. 3 was charging;

The curve map that battery open circuit voltage changed with SOC, T when Fig. 4 was discharge;

Fig. 5 is the efficiency value η change curve during battery charge under certain temperature;

Fig. 6 is the efficiency value η change curve during battery discharge under certain temperature;

Fig. 7 is the change curve of cell degradation factor beta with the charge and discharge cycles number of times.

Embodiment

As shown in Figure 1, be provided with battery current sensor 3, battery temperature sensor, current sensor, temperature sensor meet current detection circuit U3 and temperature detection loop U2 respectively, also be provided with battery voltage detection loop U1 simultaneously, the signal output part in temperature detection loop, current detection circuit and voltage detecting loop meets A/D converter U5 through data acquisition unit circuit U 4, the A/D converter signal output part meets master controller U6, and primary controller meets the instrument panel U7 of car load.

Discharge and recharge by hi-line 4 between the inverter 2 of high-tension battery 1 and car load part, master controller calculates according to charging and discharging currents signal, battery temperature signal and battery voltage signal and obtains current state-of-charge.

The computing formula of current state-of-charge is an ampere-hour integral equation: $\mathrm{SOC}={\mathrm{SOC}}_0+\∫\frac{I*t}{\mathrm{Cn}*\mathrm{\β}}\mathrm{\η},$ Wherein SOC is current charged value, SOC ₀Be the charged value before powering on, Cn is the rated capacity of battery, and η is an efficiency for charge-discharge, and β is the cell degradation coefficient, and integration variable is time t.

1, power on before charged value SOC ₀Acquisition

Before shutting down last time, store current battery charge state value SOC1 and direction of current I _Dir, the time interval t1 according between shutdown last time and this starting as shown in Figure 2, obtains self-discharge rate θ according to the self-discharge of battery curve map, and SOC1 is deducted self-discharge rate θ, promptly obtains the SOC1 ' that revises;

Read this open-circuit voltage values that powers on and temperature value simultaneously, and to above-mentioned I _DirJudge, work as I _DirDuring for positive number, as shown in Figure 3, the curve map that battery open circuit voltage changes with SOC, T during according to charging obtains modified value SOC2 ', works as I _DirDuring for negative, as shown in Figure 4, battery open circuit voltage obtains modified value SOC2 with the curve map that SOC, T change during according to discharge ";

Finally draw the charged value SOC before powering on ₀=a*SOC1 '+b SOC2 ' or SOC ₀=a*SOC1 '+b*SOC2 ", wherein a, b obtain by the time interval t1 between shutdown last time and this starting for can demarcate variable, and relation sees the following form between time interval t1 and a, the b:

(h representative hour, d represent the sky)

t1	＜2h	2h ≤t1 ≤ 6h	6h＜t1 ≤ 24h	2d	3d	4d	5d	6d	7d	8d	9d	10d	11d	12d	13d	14d	15d
																		a	1	0.97	0.95	0.92	0.89	0.86	0.83	0.8	0.77	0.74	0.71	0.68	0.65	0.62	0.59	0.56	0.53
b	0	0.03	0.05	0.08	0.11	0.14	0.17	0.2	0.23	0.26	0.29	0.32	0.35	0.38	0.41	.044	0.47

2, the acquisition of efficiency for charge-discharge η

According to the charged value SOC before powering on ₀, current battery current value, temperature value, I _DirDirection is in conjunction with the efficiency value η change curve during battery charge under certain temperature, as shown in Figure 5; Perhaps, as shown in Figure 6, obtain efficiency for charge-discharge η in conjunction with the efficiency value η change curve during battery discharge under certain temperature.

3, the acquisition of cell degradation factor beta

The cell degradation factor beta can obtain according to battery actual capacity of being surveyed after the charge and discharge cycles repeatedly and the merchant of rated capacity Cn.

As shown in Figure 7, the change curve of cell degradation factor beta and charge and discharge cycles number of times, wherein ordinate is that m back actual capacity of being surveyed of circulation and the merchant of rated capacity Cn are β.

Whole process is loop cycle with T, from certain t constantly, and as if I this moment _Dir＞0, and (t-T constantly) I of last one-period _Dir＜0, show from t moment battery to begin charging record corresponding SOC this moment _t, afterwards in service is judged I constantly _DirPositive and negative, in case certain (t+nT) I constantly _Dir＜0, show that this charge operation finishes, simultaneously record corresponding SOC this moment _T+NT

If constantly from certain t, I _Dir＜0, and (t-T constantly) I of last one-period _Dir＞0, show from t moment battery to begin discharge record corresponding SOC this moment _t, follow-up judgement thinking is identical with the beginning charging procedure; Such judgement is in order to calculate in single charge operation or the discharge operational process, the SOC situation of change of battery, in case | SOC _T+nT-SOC _t| 〉=5%, then cycle index m adds 1, otherwise m remains unchanged; Check in aging coefficient β by Fig. 7 then.

Aforesaid each curvilinear motion figure is a prior art, is implanted in advance in the primary controller, and master controller is according to equation $\mathrm{SOC}={\mathrm{SOC}}_0+\∫\frac{I*t}{\mathrm{Cn}*\mathrm{\β}}\mathrm{\η},$ Selected integration period carries out integration to the current value that is collected by integration period, and charging current is for just in the equation, and discharge current is for negative, will resulting current battery charge state value (SOC) timing renewal, and be shown on the instrument panel.

Claims (4)

1. battery charge Forecasting Methodology, it is characterized in that: discharge and recharge by hi-line between the inverter of high-tension battery and car load part, master controller calculates according to charging and discharging currents signal, battery temperature signal and battery voltage signal and obtains current state-of-charge;

The computing formula of current state-of-charge is:

Wherein SOC is current charged value, SOC ₀Be the charged value before powering on, Cn is the rated capacity of battery, and η is an efficiency for charge-discharge, and β is the cell degradation coefficient, and integration variable is time t.

2. battery charge Forecasting Methodology according to claim 1 is characterized in that:

Charged value SOC before powering on ₀Can obtain by the following method,

Before shutting down last time, store current battery charge state value SOC1 and direction of current I _Dir, the time interval t1 according between shutdown last time and this starting obtains self-discharge rate θ, and SOC1 is deducted self-discharge rate θ, promptly obtains the SOC1 ' that revises;

Read this open-circuit voltage values that powers on and temperature value simultaneously, and to above-mentioned I _DirJudge, work as I _DirDuring for positive number, obtain modified value SOC2 ', work as I _DirDuring for negative, obtain modified value SOC2 ";

Finally draw the charged value SOC before powering on ₀=a*SOC1 '+b*SOC2 ' or SOC ₀=a*SOC1 '+b*SOC2 ", wherein a, b obtain by the time interval t1 between shutdown last time and this starting for can demarcate variable, and relation is as follows between time interval t1 and a, the b:

During t1＜2h, a=1, b=0;

During 2h≤t1≤6h, a=0.97, b=0.03;

During 6h＜t1≤24h, a=0.95, b=0.05;

During t1=2d, a=0.92, b=0.08;

During t1=3d, a=0.89, b=0.11;

During t1=4d, a=0.86, b=0.14;

During t1=5d, a=0.83, b=0.17;

During t1=6d, a=0.8, b=0.2;

During t1=7d, a=0.77, b=0.23;

During t1=8d, a=0.74, b=0.26;

During t1=9d, a=0.71, b=0.29;

During t1=10d, a=0.68, b=0.32;

During t1=11d, a=0.65, b=0.35;

During t1=12d, a=0.62, b=0.38;

During t1=13d, a=0.59, b=0.41;

During t1=14d, a=0.56, b=0.44;

During t1=15d, a=0.53, b=0.47;

Wherein, h representative hour, d represents the sky.

3. battery charge Forecasting Methodology according to claim 2 is characterized in that: efficiency for charge-discharge η can be according to the charged value SOC before powering on ₀, current battery current value, temperature value and I _DirDirection obtains.

4. battery charge Forecasting Methodology according to claim 3 is characterized in that: the cell degradation factor beta can obtain according to battery actual capacity of being surveyed after the charge and discharge cycles repeatedly and the merchant of rated capacity Cn.

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