CN106855611A - A kind of battery SOC evaluation method and system - Google Patents

Abstract

The present invention provides a kind of battery SOC evaluation method, comprises the following steps：Gather the temperature T and charging and discharging currents I of some cells；Tabled look-up according to the charging and discharging currents I and temperature T of the cell and obtain efficiency for charge-discharge η_T；Calculate the relative SoC of the cell_R；Table look-up the charging capacity Q respectively obtained under the temperature T according to the charging and discharging currents I and temperature T of the cell_CTAnd discharge capacity Q_DT；Calculate recoverable unavailable charging capacity of the cell under the temperature TAnd recoverable unavailable discharge capacityCalculate the SoC of the cell under Current Temperatures T_T.The SOC that the battery SOC evaluation method that the present invention is provided can go out under Current Temperatures according to the change calculations of temperature, and then ensure that battery SOC precision at different temperatures.The present invention also provides a kind of battery SOC estimating system.

Description

A kind of battery SOC evaluation method and system

【Technical field】

The present invention relates to battery management system technical field, more particularly to a kind of battery SOC evaluation method and system.

【Background technology】

The active volume of ferric phosphate lithium cell is closely bound up with temperature and discharge-rate, due to its Europe at low temperatures Nurse internal resistance and polarization resistance are far longer than its ohmic internal resistance and polarization resistance in the case of normal temperature, and then cause ferric phosphate Lithium battery active volume at low temperatures is influenceed more serious by temperature and discharge-rate.Charged for setting identical Blanking voltage and discharge cut-off voltage, battery when it reaches charge cutoff voltage at different temperatures charging capacity it is special by difference Be not that its charging capacity only has under normal temperature under low temperature condition 70%, even less than 70%.Similarly, battery is at different temperatures Electric discharge is also the same situation, the capacity put under the capacity put far smaller than normal temperature under low temperature.

However, thering is the portion capacity to recover with the rise of battery temperature in the capacity for reducing.Therefore, when to battery When SOC is estimated, if ignore battery temperature influence, it will cause SOC (State of Charge, state-of-charge) compared with Battery has reached blanking voltage when high, so as to cause vehicle to travel, even results in cell damage.

In consideration of it, real be necessary to provide a kind of new battery SOC evaluation method and system to overcome drawbacks described above.

【The content of the invention】

It is an object of the invention to provide a kind of battery SOC evaluation method and system, the battery SOC evaluation method and system The SOC that can go out under Current Temperatures according to the change calculations of temperature, and then ensure that battery SOC precision at different temperatures.

To achieve these goals, the present invention provides a kind of battery SOC evaluation method, and it is applied in electric automobile, institute Stating electric automobile includes the battery bag for being used to provide power for it, and the battery bag includes some cells；The battery SOC Evaluation method comprises the following steps：

Gather the temperature T and charging and discharging currents I of some cells；

Tabled look-up according to the charging and discharging currents I and temperature T of the cell and obtain efficiency for charge-discharge η_T；

Calculate the relative SoC of the cell_R；

Tabled look-up according to the charging and discharging currents I and temperature T of the cell charging capacity respectively obtained under the temperature T Q_CTAnd discharge capacity Q_DT；

Calculate recoverable unavailable charging capacity of the cell under the temperature TAnd can recover Unavailable discharge capacity

Calculate the SoC of the cell under Current Temperatures T_T。

The present invention also provides a kind of battery SOC estimating system, and it is applied in electric automobile, and the electric automobile includes using Yu Weiqi provides the battery bag of power, and the battery bag includes some cells；The battery SOC estimating system includes collection Module, table look-up module and computing module；The acquisition module is used to gather temperature T and the charge and discharge of some cells Electric current I；The table look-up module is used to be tabled look-up according to the charging and discharging currents I and temperature T of the cell and obtains discharge and recharge effect Rate η_T；The computing module is used to calculate the relative SoC of the cell_R；The table look-up module is additionally operable to according to the monomer The charging and discharging currents I and temperature T of battery table look-up the charging capacity Q respectively obtained under the temperature T_CTAnd discharge capacity Q_DT；It is described Computing module is additionally operable to calculate recoverable unavailable charging capacity of the cell under the temperature TAnd Recoverable unavailable discharge capacityThe computing module is additionally operable to calculate the monomer electricity under Current Temperatures T The SoC in pond_T。

Battery SOC evaluation method and system that the present invention is provided, have taken into full account shadow of the temperature to the cell SOC Ring, further, it is contemplated that the cell recovers unavailable capacity to the cell SOC's during temperature change Influence, and then improve the estimation precision of the cell SOC.

【Brief description of the drawings】

Fig. 1 is the functional block diagram of the electric automobile comprising the battery SOC estimating system for providing of the invention.

The flow chart of the battery SOC evaluation method that Fig. 2 is provided for the present invention.

【Specific embodiment】

In order that the purpose of the present invention, technical scheme and Advantageous Effects become apparent from understanding, below in conjunction with accompanying drawing and Specific embodiment, the present invention will be described in further detail.It should be appreciated that the specific implementation described in this specification Mode is not intended to limit the present invention just for the sake of explaining the present invention.

Fig. 1 is referred to, is the functional module of the electric automobile 99 comprising the battery SOC estimating system 200 for providing of the invention Figure.The electric motor car 99 includes battery bag 100, battery SOC estimating system 200, memory 300 and processor 400.The electricity Pond bag 100 is used to provide power for the electric automobile 99.In the present embodiment, the battery bag 100 includes some monomers Battery.The battery SOC estimating system 200 includes acquisition module 10, table look-up module 20 and computing module 30.It is appreciated that Ground, above-mentioned each functional module can be stored in memory 300 in form of software programs, and be performed by processor 400.Substituting In embodiment, above-mentioned each functional module is alternatively the hardware with specific function, for example, burning has the core of particular software application Piece.

Above-mentioned each functional module is described in detail with reference to Fig. 2.

As shown in Fig. 2 it is the flow chart of battery SOC evaluation method in the embodiment of the present invention.It should be noted that, this hair Bright method is not limited to the order of following step, and in other embodiment, the method for the present invention can only include following institute A portion of step is stated, or part steps therein can be deleted.

S01, acquisition module 10 is used to gather the temperature T and charging and discharging currents I of some cells.

Specifically, in the present embodiment, the acquisition module 10 is illustrated by taking battery management system as an example.Cell tube The Core Feature of reason system is that the battery bag 100 is managed, and the collection of cell voltage, electric current and temperature is its base One of this function, therefore, any a battery management system can realize the acquisition function of cell voltage, electric current and temperature.

S02, the table look-up module 20 is used to table look-up and be filled according to the charging and discharging currents I and temperature T of the cell Discharging efficiency η_T。

It is appreciated that efficiency for charge-discharge η_TCan be using off-line test method at different temperatures using different electric currents to institute Stating battery bag 100 carries out discharge and recharge and records the efficiency for charge-discharge η corresponding to different electric currents_T, and it is stored in the memory 300 In.

S03, the computing module 30 is used to calculate the relative SoC of the cell_R。

Specifically, in the present embodiment, the relative SoC of the cell is calculated_RSpecific formula it is as follows：

Wherein, the SoC_RIt is the relative SOC of the cell under equal state, the formula (1) is that relative SOC estimates Calculation method, what it was estimated is the residual capacity of the cell；The Q_RIt is the capacity of the cell under room temperature environment； η_TIt is the efficiency for charge-discharge of battery under temperature T.

S04, the table look-up module 20 is used to be tabled look-up according to the charging and discharging currents I and temperature T of the cell and obtain respectively Charging capacity Q under to temperature T_CTAnd discharge capacity Q_DT。

Specifically, the charging capacity Q_CTFor the monocell temperature be T degrees Celsius when voltage for 3.65V capacity When temperature is 20 degrees Celsius, voltage is the difference of the capacity of 2.65V with the cell.In the present embodiment, it is described to fill Capacitance Q_CTComputing formula it is as follows：

The discharge capacity Q_DTFor the monocell the voltage when temperature is 20 degrees Celsius for 3.65V capacity with it is described Cell voltage when temperature is T degrees Celsius is the difference of the capacity of 2.65V.In the present embodiment, the charging capacity Q_CTComputing formula it is as follows：

S05, the recoverable unavailable of the cell that the computing module 30 is used to calculate under the temperature T fills CapacitanceAnd recoverable unavailable discharge capacity

Specifically, the recoverable unavailable charging capacity is calculatedAnd recoverable unavailable discharge capacityFormula respectively it is as follows：

Wherein, Q_RIt is the capacity of battery under room temperature environment；Q_CTFor the charging of the cell at T degrees Celsius of temperature is held Amount；Q_DTIt is the discharge capacity of the cell at T degrees Celsius of temperature；It is the monomer at T degrees Celsius of temperature The recoverable unavailable charging capacity of battery；For at T degrees Celsius of temperature the cell it is recoverable not Can discharge capacity.It is appreciated that the temperature is the discharge capacity Q of the cell under T degrees Celsius_DT, battery charging capacity Q_CTAnd under room temperature environment battery capacity Q_RCan be obtained by off-line test and tabling look-up, then be obtained according to formula (4) and (5) again The recoverable unavailable charging capacity of the cell under relevant temperatureWith recoverable unavailable electric discharge Capacity

S06, the computing module 30 is additionally operable to calculate the SoC of the cell under Current Temperatures T_T。

Specifically, the SoC of battery under the Current Temperatures T is calculated_TFormula respectively it is as follows：

According to quantity of electric charge law of conservation and can to recover unavailable capacity related not with the SOC for stating cell, with Charge-discharge magnification and temperature are related, therefore, charging SOC and the electric discharge under relevant temperature T can be obtained according to formula (6) and (7) SOC.Further, the formula (6) is the computational methods of the charging SOC under T degrees Celsius of Current Temperatures；The formula (7) is The computational methods of the electric discharge SOC under T degrees Celsius of Current Temperatures.

Battery SOC evaluation method provided by the present invention and system 200, have taken into full account temperature to the cell The influence of SOC, further, it is contemplated that the cell recovers unavailable capacity to the monomer electricity during temperature change The influence of pond SOC, and then improve the estimation precision of the cell SOC.

The present invention is not restricted to described in specification and implementation method, therefore for the personnel of familiar field Additional advantage and modification are easily achieved, therefore in the essence of the universal limited without departing substantially from claim and equivalency range In the case of god and scope, the present invention is not limited to specific details, representational equipment and shown here as the diagram with description Example.

Claims (10)

1. a kind of battery SOC evaluation method, it is applied in electric automobile, and the electric automobile is included for providing power for it Battery bag, the battery bag include some cells；It is characterized in that：The battery SOC evaluation method includes following step Suddenly：

Gather the temperature T and charging and discharging currents I of some cells；

Tabled look-up according to the charging and discharging currents I and temperature T of the cell and obtain efficiency for charge-discharge η_T；

Calculate the relative SoC of the cell_R；

Table look-up the charging capacity Q respectively obtained under the temperature T according to the charging and discharging currents I and temperature T of the cell_CTAnd Discharge capacity Q_DT；

Calculate recoverable unavailable charging capacity of the cell under the temperature TAnd it is recoverable not Discharge capacity can be used

Calculate the SoC of the cell under Current Temperatures T_T。

2. battery SOC evaluation method as claimed in claim 1, it is characterised in that：It is described to calculate the relative of the cell SoC_RSpecific formula it is as follows：

${\mathrm{SoC}}_R\left(t\right)={\mathrm{SoC}}_R(t-1)-\frac{{\mathrm{\η}}_T\∫idt}{Q_R}$

Wherein, the SoC_RThe relative SOC of the cell under for temperature T；The Q_RIt is the monomer electricity under room temperature environment The capacity in pond；η_TIt is the efficiency for charge-discharge of battery under the temperature T.

3. battery SOC evaluation method as claimed in claim 2, it is characterised in that：The charging capacity Q_CTIt is the monocell When the temperature is T degrees Celsius voltage for 3.65V capacity and the cell when the temperature is 20 degrees Celsius electricity Press the difference of the capacity for 2.65V；The charging capacity Q_CTComputing formula it is as follows：

$Q_{CT}={\∫}_{{265}_{20}}^{{365}_T}idt;$

The discharge capacity Q_DTFor the monocell, when the temperature is 20 degrees Celsius, voltage is the capacity and the list of 3.65V Body battery voltage when the temperature is T degrees Celsius is the difference of the capacity of 2.65V；The charging capacity Q_CTComputing formula such as Under：

$Q_{DT}={\∫}_{{2.65}_T}^{{3.65}_{20}}idt.$

4. battery SOC evaluation method as claimed in claim 3, it is characterised in that：It is described to calculate the cell described Described recoverable unavailable charging capacity under temperature TAnd the recoverable unavailable discharge capacityFormula respectively it is as follows：

$Q_{CT}+{\mathrm{LFC}}_{T_R-T}=Q_R;$

$Q_{DT}+{\mathrm{LFD}}_{T_R-T}=Q_R;$

Wherein, Q_RIt is the capacity of the cell under room temperature environment；Q_CTIt is the charging of the cell at T degrees Celsius of temperature Capacity；Q_DTIt is the discharge capacity of the cell at T degrees Celsius of temperature；It is the list at T degrees Celsius of temperature The recoverable unavailable charging capacity of body battery；For at T degrees Celsius of temperature the cell it is recoverable Can not discharge capacity.

5. battery SOC evaluation method as claimed in claim 4, it is characterised in that：The institute calculated under the Current Temperatures T State the SoC of cell_TFormula respectively it is as follows：

${\mathrm{SoC}}_T=\frac{{\mathrm{SoC}}_R*Q_R-{\mathrm{LFC}}_{T_R-T}}{Q_{CT}};$

${\mathrm{SoC}}_T=\frac{{\mathrm{SoC}}_R*Q_R-{\mathrm{LFD}}_{T_R-T}}{Q_{DT}}.$

6. battery SOC estimating system as claimed in claim 5, it is applied in electric automobile, and the electric automobile includes using Yu Weiqi provides the battery bag of power, and the battery bag includes some cells；It is characterized in that：The battery SOC estimation System includes acquisition module, table look-up module and computing module；The acquisition module is used to gather some cells Temperature T and charging and discharging currents I；The table look-up module is used to be tabled look-up according to the charging and discharging currents I and temperature T of the cell Obtain efficiency for charge-discharge η_T；The computing module is used to calculate the relative SoC of the cell_R；The table look-up module is additionally operable to Table look-up the charging capacity Q respectively obtained under the temperature T according to the charging and discharging currents I and temperature T of the cell_CTAnd electric discharge Capacity Q_DT；The computing module is additionally operable to calculate recoverable unavailable charging appearance of the cell under the temperature T AmountAnd recoverable unavailable discharge capacityThe computing module is additionally operable to calculate under Current Temperatures T The cell SoC_T。

7. battery SOC estimating system as claimed in claim 6, it is characterised in that：It is described to calculate the relative of the cell SoC_RSpecific formula it is as follows：

${\mathrm{SoC}}_R\left(t\right)={\mathrm{SoC}}_R(t-1)-\frac{{\mathrm{\η}}_T\∫idt}{Q_R}$

Wherein, the SoC_RThe relative SOC of the cell under for temperature T；The Q_RIt is the monomer electricity under room temperature environment The capacity in pond；η_TIt is the efficiency for charge-discharge of battery under the temperature T.

8. battery SOC estimating system as claimed in claim 7, it is characterised in that：The charging capacity Q_CTIt is the monocell It is that the voltage when temperature is 20 degrees Celsius is the capacity of 3.65V with the cell in the voltage when temperature is T degrees Celsius The difference of the capacity of 2.65V；The charging capacity Q_CTComputing formula it is as follows：

$Q_{CT}={\∫}_{{2.65}_{20}}^{{3.65}_T}idt;$

The discharge capacity Q_DTBe the monocell the voltage when temperature is 20 degrees Celsius for 3.65V capacity and the monomer Battery voltage when temperature is T degrees Celsius is the difference of the capacity of 2.65V；The charging capacity Q_CTComputing formula it is as follows：

$Q_{DT}={\∫}_{{2.65}_T}^{{3.65}_{20}}idt.$

9. battery SOC estimating system as claimed in claim 8, it is characterised in that：It is described to calculate the cell described Described recoverable unavailable charging capacity under temperature TAnd the recoverable unavailable discharge capacityFormula respectively it is as follows：

$Q_{CT}+{\mathrm{LFC}}_{T_R-T}=Q_R;$

$Q_{DT}+{\mathrm{LFD}}_{T_R-T}=Q_R;$

Wherein, Q_RIt is the capacity of battery under room temperature environment；Q_CTIt is the charging capacity of the cell at T degrees Celsius of temperature；Q_DT It is the discharge capacity of the cell at T degrees Celsius of temperature；It is the cell at T degrees Celsius of temperature Recoverable unavailable charging capacity；For the recoverable of the cell can not discharge at T degrees Celsius of temperature Capacity.

10. battery SOC estimating system as claimed in claim 9, it is characterised in that：It is described to calculate under the Current Temperatures T The SoC of the cell_TFormula respectively it is as follows：

${\mathrm{SoC}}_T=\frac{{\mathrm{SoC}}_R*Q_R-{\mathrm{LFC}}_{T_R-T}}{Q_{CT}};$

${\mathrm{SoC}}_T=\frac{{\mathrm{SoC}}_R*Q_R-{\mathrm{LFD}}_{T_R-T}}{Q_{DT}}.$