CN102903976A - State of charge (SOC) correction method in pure electric vehicle charging process - Google Patents

Abstract

A state of charge (SOC) correction method in the pure electric vehicle charging process includes a charging mode, a charging pre-correction mode, a constant-current charging stage and a constant-pressure current-reducing charging stage. Compared with the prior art, the SOC correction method has the advantages that residual capacity estimation is accurate due to the fact that SOC correction in the charging process is added on the basis of dynamic SOC correction in the discharging process presently; the battery charging amount is increased, battery service life is prolonged, correction is carried out as long as charging starts, and accordingly the charging amount is increased; and lithium ion batteries are used in the fully charged state, and accordingly service life of the lithium ion batteries can be prolonged.

Description

A kind of pure electric automobile charging process SOC modification method

Technical field

The invention belongs to the batteries of electric automobile management domain, specifically the modification method of the SOC in the pure electric automobile charging process improves.

Background technology

SOC(is state-of-charge, the ratio of capacity when the residual capacity of finger storage battery and its are full of electricity condition fully) as the parameter of weighing the battery pack dump energy, the driver is played a very important role, as can not accurately grasping the dump energy of battery, can cause electric automobile because not having electricity to stop risk in the road.In order to weigh accurately the dump energy of battery pack, the battery management system of at present some technological precedences (hereinafter to be referred as BMS) adopts the method for revising SOC in running car, reaches the purpose of accurate estimation dump energy.But the fact of battery cell inconsistency objective reality, the poor cell of some characteristics cause battery pack can not be full of fully when charging, and SOC has been shown as 100 according to the ceiling voltage monomer, and this will cause the SOC estimation to have error.

In the battery management system field, major part all is the estimation according to voltage static state at present; The technology that some technology are leading in order accurately to estimate SOC, is also just taked at present dynamically to revise the SOC value in running car, and is not revised in the charging process.Because the battery cell inconsistency causes battery pack to be full of fully, the estimation of SOC brings error like this.

Summary of the invention

In view of this, the technical problem to be solved in the present invention is the pure electric automobile charging process SOC modification method that estimation is accurate, adopt dynamic correction.

In order to solve the problems of the technologies described above, this technical problem adopts following solution:

A kind of pure electric automobile charging process SOC modification method, the method comprises the steps:

A). enter charge mode, detect cell and whether satisfy simultaneously minimum temperature 〉=X degree centigrade, charging current 〉=Y ampere, duration of charge 〉=Z minute, if satisfy above-mentioned condition, then enter the pre-modification model of charging, otherwise enter the c step constant current charge stage;

B). enter the pre-modification model of charging, according to the scope of the minimum monomer voltage Vmin in the battery pack, select suitable SOC correcting mode to revise under this pattern, revise and enter next step after complete;

C). enter the constant current charge stage, this stage charges with constant electric current according to the SOC value that obtains in the b step, until monomer battery voltage reaches the upper voltage limit threshold values;

D). enter the constant-pressure drop current charge stage, the mode that this stage is reduced electric current with constant voltage, is gradually charged, until charging current is reduced to till 0 the complete charge process;

E). enter the terminal SOC of charging and revise step, if SOC is not equal to 100% during this step, then need be modified to 100 to SOC.

Wherein, described charging modification model is:

When minimum monomer voltage Vmin satisfies 2.5V≤Vmin≤3 V, SOC=10* Vmin-25;

When 3 V＜Vmin≤3.2V, SOC=25* Vmin-70;

When 3.2V＜Vmin≤3.3V, SOC=200* Vmin-630;

As 3.3V＜Vmin＜3.373V, and SOC≤35, then directly SOC is adapted to 30;

As Vmin 〉=3.373V, and SOC≤85 o'clock, directly SOC is adapted to 80.

Compared with prior art, the present invention has following advantage:

1. the dump energy estimation is more accurate, is dynamically revising on the basis of SOC in the discharge process at present, adds that SOC revises in the charging process, has so just increased the accuracy of dump energy estimation.

2. increased the battery charge volume, prolonged battery, charging is initially revised, and has increased charge volume; Lithium ion battery is full of electricity condition to be used, and can prolong its useful life.

Embodiment

For the ease of it will be appreciated by those skilled in the art that below in conjunction with embodiment the present invention is described in further detail:

The pure electric automobile charging process SOC modification method that present embodiment discloses, the method comprises the steps:

A). enter charge mode, detect cell and whether satisfy simultaneously minimum temperature 〉=X degree centigrade, charging current 〉=Y ampere, duration of charge 〉=Z minute, if satisfy above-mentioned condition, then enter the pre-modification model of charging, otherwise enter the c step constant current charge stage;

B). enter the pre-modification model of charging, according to the scope of the minimum monomer voltage Vmin in the battery pack, select suitable SOC correcting mode to revise under this pattern, revise and enter next step after complete;

C). enter the constant current charge stage, this stage charges with constant electric current according to the SOC value that obtains in the b step, until monomer battery voltage reaches the upper voltage limit threshold values;

D). enter the constant-pressure drop current charge stage, the mode that this stage is reduced electric current with constant voltage, is gradually charged, until charging current is reduced to till 0 the complete charge process;

E). enter the terminal SOC of charging and revise step, if SOC is not equal to 100% during this step, then need be modified to 100 to SOC.

Wherein, the parameter X value is 15, and parameter Y value 4, parameter Z value are 10.In the present embodiment, parameter X, Y, Z determine according to cell characteristic commonly used in the existing electric automobile, are the empirical statistics value, span is generally: X can be [13,17] value, as 13 or 17, Y can be [3,5] scope value, as 3 or 5, Z can be in [8,12] scope value, such as 8 or 12, can reach identical goal of the invention equally.

For C) the constant electric current that adopts of charging in the step is according to cell characteristic commonly used in the existing electric automobile, and its value is generally 1C, and this value also is the empirical statistics value.

For d) constant voltage in the step determines that according to battery cell ceiling voltage higher limit different battery cell values are different, necessary disclosed parameter can directly obtain from each parameter of battery cell that manufacturer provides when this value was dispatched from the factory for battery cell.For the frequency and the size that reduce gradually electric current in this step, also can decide according to the characteristic of battery cell, this step method is more common in battery charging field, is the prior art scheme, and therefore not to repeat here.

Wherein, described charging modification model is:

When minimum monomer voltage Vmin satisfies 2.5V≤Vmin≤3 V, SOC=10* Vmin-25;

When 3 V＜Vmin≤3.2V, SOC=25* Vmin-70;

When 3.2V＜Vmin≤3.3V, SOC=200* Vmin-630;

As 3.3V＜Vmin＜3.373V, and SOC≤35, then directly SOC is adapted to 30;

As Vmin 〉=3.373V, and SOC≤85 o'clock, directly SOC is adapted to 80.

In practice, the value of SOC all is with percent value, in this programme, and for formula calculates simply, thus the % of SOC value is removed, and directly adopt simple numerical value.

Above-described embodiment only is wherein specific implementation of the present invention, and it describes comparatively concrete and detailed, but can not therefore be interpreted as the restriction to claim of the present invention.Should be pointed out that for the person of ordinary skill of the art, without departing from the inventive concept of the premise, can also make some distortion and improvement, these apparent replacement forms all belong to protection scope of the present invention.

Claims (2)

1. a pure electric automobile charging process SOC modification method is characterized in that the method comprises the steps:

A). enter charge mode, detect cell and whether satisfy simultaneously minimum temperature 〉=X degree centigrade, charging current 〉=Y ampere, duration of charge 〉=Z minute, if satisfy above-mentioned condition, then enter the pre-modification model of charging, otherwise enter the c step constant current charge stage;

B). enter the pre-modification model of charging, according to the scope of the minimum monomer voltage Vmin in the battery pack, select suitable SOC correcting mode to revise under this pattern, revise and enter next step after complete;

C). enter the constant current charge stage, this stage charges with constant electric current according to the SOC value that obtains in the b step, until monomer battery voltage reaches the upper voltage limit threshold values;

D). enter the constant-pressure drop current charge stage, the mode that this stage is reduced electric current with constant voltage, is gradually charged, until charging current is reduced to till 0 the complete charge process;

E). enter the terminal SOC of charging and revise step, if SOC is not equal to 100% during this step, then need be modified to 100 to SOC.

2. pure electric automobile charging process SOC modification method according to claim 1 is characterized in that described charging modification model is:

When minimum monomer voltage Vmin satisfies 2.5V≤Vmin≤3 V, SOC=10* Vmin-25;

When 3 V＜Vmin≤3.2V, SOC=25* Vmin-70;

When 3.2V＜Vmin≤3.3V, SOC=200* Vmin-630;

As 3.3V＜Vmin＜3.373V, and SOC≤35, then directly SOC is adapted to 30;

As Vmin 〉=3.373V, and SOC≤85 o'clock, directly SOC is adapted to 80.