Disclosure of Invention
The invention provides a method and a system for correcting SOH of an electric automobile, which solve the problem that the SOH estimation value of the conventional electric automobile is inaccurate, and can improve the safety and intelligence of the electric automobile.
In order to achieve the above purpose, the invention provides the following technical scheme:
an SOH correction method of an electric vehicle comprises the following steps:
obtaining a corresponding relation between the open-circuit voltage OCV of the vehicle power battery and the SOC of the power battery through tests, and establishing an OCV-SOC corresponding table of the power battery;
when the power battery is charged and discharged after being fully charged in a slow charging mode, the accumulated discharge capacity C of the battery is obtained1And the cumulative charging capacity C2;
Before the next time of full charge of the power battery, judging whether the power battery meets the condition of correcting the SOC of the power battery by adopting the open-circuit voltage OCV;
if yes, obtaining the open-circuit voltage OCV of the power battery, and obtaining the corresponding SOC through the OCV-SOC corresponding table lookupOCVCorrection value according to SOCOCVAnd correcting the SOH of the power battery by the correction value.
Preferably, the method further comprises the following steps:
if not, accumulating the discharge capacity C according to the battery after the electric quantity of the vehicle is completely discharged1And the accumulated charging capacity C2And calculating to obtain the SOH of the power battery.
Preferably, theAccording to SOCOCVThe correction value is used for correcting the SOH of the power battery and comprises the following steps:
according to the formula:
calculating to obtain the actual capacity C of the power battery
S;
Obtaining rated capacity C of power battery
eAnd according to the formula:
obtaining a calculated value of SOH;
and correcting the calculated SOH value as the SOH of the power battery.
Preferably, the discharge capacity C is accumulated according to the battery1And the accumulated charging capacity C2Calculating the SOH of the power battery, comprising the following steps:
according to the formula: cS=C1-C2Calculating to obtain the actual capacity C of the power batteryS;
And taking the ratio of the actual capacity to the rated capacity of the power battery as the SOH correction value of the power battery.
Preferably, the determining whether the power battery satisfies the condition for correcting the SOC of the power battery using the open-circuit voltage OCV includes:
and whether the power battery of the vehicle is kept in a static state for more than or equal to 1h, and if so, the collected lowest voltage of the battery cells is taken as the open-circuit voltage OCV of the power battery.
The invention also provides an SOH correction system of an electric vehicle, comprising:
the setting unit is used for obtaining a corresponding relation between the open-circuit voltage OCV of the vehicle power battery and the SOC of the power battery through tests and establishing an OCV-SOC corresponding table of the power battery;
an obtaining unit for obtaining the accumulated discharge capacity C of the battery when the power battery is charged and discharged after being fully charged in a slow charging mode1And the cumulative charging capacity C2;
The judging unit is used for judging whether the power battery meets the condition of correcting the SOC of the power battery by adopting the open-circuit voltage OCV or not before the next full charge of the power battery;
the first correction unit is used for acquiring the open-circuit voltage OCV of the power battery when the power battery meets the condition of correcting the SOC of the power battery by adopting the open-circuit voltage OCV, and obtaining the corresponding SOC through the OCV-SOC corresponding tableOCVCorrection value according to SOCOCVAnd correcting the SOH of the power battery by the correction value.
Preferably, the method further comprises the following steps:
a second correcting unit for correcting the SOC of the power battery according to the accumulated discharge capacity C of the power battery when the power battery does not meet the condition of correcting the SOC of the power battery by adopting the open-circuit voltage OCV and the vehicle is completely discharged1And the accumulated charging capacity C2And calculating to obtain the SOH of the power battery.
Preferably, the first correcting unit includes:
a first battery capacity calculation unit for calculating a battery capacity of the battery according to the formula:
calculating to obtain the actual capacity C of the power battery
S;
A first SOH calculation unit for obtaining rated capacity C of the power battery
eAnd according to the formula:
and obtaining a calculated SOH value, and correcting the calculated SOH value as the SOH of the power battery.
Preferably, the second correction unit includes:
a second battery capacity calculation unit for calculating a second battery capacity according to the formula: cS=C1-C2Calculating to obtain the actual capacity C of the power batteryS;
And the second SOH calculation unit is used for taking the ratio of the actual capacity to the rated capacity of the power battery as the SOH correction value of the power battery.
Preferably, the judging unit includes:
and the standing judgment unit is used for judging whether the power battery of the vehicle is kept in a standing state for more than or equal to 1h, and if so, the collected lowest voltage of the battery cells is taken as the open-circuit voltage OCV of the power battery.
The invention provides a method and a system for correcting SOH of an electric vehicle. The problem of inaccurate SOH estimated value of current electric automobile is solved, security and the intellectuality that electric automobile used can be improved.
Detailed Description
In order to make the technical field of the invention better understand the scheme of the embodiment of the invention, the embodiment of the invention is further described in detail with reference to the drawings and the implementation mode.
Aiming at the problem that the SOH estimation value of the power battery of the conventional electric automobile is inaccurate, the invention provides the SOH correction method and the SOH correction system of the electric automobile. The problem of inaccurate SOH estimated value of current electric automobile is solved, security and the intellectuality that electric automobile used can be improved.
As shown in fig. 1, a method for correcting SOH of an electric vehicle includes:
s1: obtaining a corresponding relation between the open-circuit voltage OCV of the vehicle power battery and the SOC of the power battery through tests, and establishing an OCV-SOC corresponding table of the power battery;
s2: when the power battery is charged and discharged after being fully charged in a slow charging mode, the accumulated discharge capacity C of the battery is obtained1And the cumulative charging capacity C2;
S3: before the next time of full charge of the power battery, judging whether the power battery meets the condition of correcting the SOC of the power battery by adopting the open-circuit voltage OCV;
s4: if yes, obtaining the open-circuit voltage OCV of the power battery, and obtaining the corresponding SOC through the OCV-SOC corresponding table lookupOCVCorrection value according to SOCOCVAnd correcting the SOH of the power battery by the correction value.
In practical application, the real SOH value of the battery at the moment can be calculated by counting the actual discharge capacity of the battery at the moment under different running states of different batteries and the same battery. And with the gradual attenuation of the battery, the SOH of the power battery is corrected according to the OCV corrected SOC value, so that the accuracy is improved.
The method further comprises the following steps:
s5: if not, accumulating the discharge capacity C according to the battery after the electric quantity of the vehicle is completely discharged1And the accumulated charging capacity C2And calculating to obtain the SOH of the power battery.
Further, the method is based on SOCOCVThe correction value is used for correcting the SOH of the power battery and comprises the following steps:
according to the formula:
calculating to obtain the actual capacity C of the power battery
S;
Obtaining rated capacity C of power battery
eAnd according to the formula:
obtaining a calculated value of SOH;
and correcting the calculated SOH value as the SOH of the power battery.
In practical application, a three-cell pure electric car of a certain type is taken as an example for explanation. After the vehicle is full, carrying out three discharging working conditions and two charging working conditions, then carrying out OCV correction, and correcting the SOC correction value SOC at the moment
OCV18%, cumulative battery discharge capacity C
174.56AH, cumulative charging capacity C
215.88AH, the actual capacity of the battery at that time
And then can obtain according to the formula
Further, the accumulated discharge capacity C according to the battery1And the accumulated charging capacity C2Calculating the SOH of the power battery, comprising the following steps: according to the formula: cS=C1-C2Calculating to obtain the actual capacity C of the power batteryS(ii) a And taking the ratio of the actual capacity to the rated capacity of the power battery as the SOH correction value of the power battery.
In practical application, a certain type of lithium iron battery pure electric car is taken as an example for explanation. After the vehicle is fully charged by self-slow charge, the OCV correction is not carried out until the electric quantity of the vehicle is completely emptied, and the accumulated discharge capacity C of the battery is counted
164.37AH, cumulative charging capacity C
27.68 AH; according to the formula, the following can be calculated: c
S=C
2-C
1=64.37-7.68=56.69AH,
The condition for judging whether the power battery meets the condition of correcting the SOC of the power battery by adopting the open-circuit voltage OCV comprises the following steps: and whether the power battery of the vehicle is kept in a static state for more than or equal to 1h, and if so, the collected lowest voltage of the battery cells is taken as the open-circuit voltage OCV of the power battery.
Specifically, according to the electrochemical characteristics of the battery, the SOC value of the battery has a specific correspondence relationship with the open-circuit voltage OCV thereof, and thus an accurate SOC value thereof can be obtained by measuring the OCV of the battery; the OCV value is the lowest voltage of the single battery after the battery is kept in a standing state for more than or equal to 1h, and corresponds to the lowest voltage of the single battery collected at the moment when a vehicle is electrified again in the running process of an actual client, namely if the vehicle is stopped and the power is off for more than 1h, namely the OCV value of the battery; according to the value, the accurate SOC value SOC corrected by OCV can be obtained by looking up a tableOCV。
Therefore, the invention provides an SOH correction method of an electric vehicle, which comprises the steps of setting an OCV-SOC correspondence table, correcting the SOC value of a power battery through the OCV when the conditions are met, and further correcting the SOH of the power battery. The problem of inaccurate SOH estimated value of current electric automobile is solved, security and the intellectuality that electric automobile used can be improved.
The invention also provides an SOH correction system of an electric vehicle, comprising: and the setting unit is used for obtaining the corresponding relation between the open-circuit voltage OCV of the vehicle power battery and the SOC of the power battery through tests and establishing an OCV-SOC corresponding table of the power battery. An obtaining unit for obtaining the accumulated discharge capacity C of the battery when the power battery is charged and discharged after being fully charged in a slow charging mode1And the cumulative charging capacity C2. And the judging unit is used for judging whether the power battery meets the condition of correcting the SOC of the power battery by adopting the open-circuit voltage OCV before the next full charge of the power battery. The first correction unit is used for acquiring the open-circuit voltage OCV of the power battery when the power battery meets the condition of correcting the SOC of the power battery by adopting the open-circuit voltage OCV, and obtaining the corresponding SOC through the OCV-SOC corresponding tableOCVCorrection value according to SOCOCVAnd correcting the SOH of the power battery by the correction value.
The system further comprises: a second correcting unit for correcting the SOC of the power battery according to the accumulated discharge capacity C of the power battery when the power battery does not meet the condition of correcting the SOC of the power battery by adopting the open-circuit voltage OCV and the vehicle is completely discharged1And the accumulated charging capacity C2And calculating to obtain the SOH of the power battery.
Further, the first correction unit includes: a first battery capacity calculation unit for calculating a battery capacity of the battery according to the formula:
calculating to obtain the actual capacity C of the power battery
S. A first SOH calculation unit for obtaining rated capacity C of the power battery
eAnd according to the formula:
obtaining a calculated value of SOH, and taking the calculated value of SOH as motionThe power cell SOH is corrected.
Further, the second correction unit includes: a second battery capacity calculation unit for calculating a second battery capacity according to the formula: cS=C1-C2Calculating to obtain the actual capacity C of the power batteryS. And the second SOH calculation unit is used for taking the ratio of the actual capacity to the rated capacity of the power battery as the SOH correction value of the power battery.
The judging unit includes: and the standing judgment unit is used for judging whether the power battery of the vehicle is kept in a standing state for more than or equal to 1h, and if so, the collected lowest voltage of the battery cells is taken as the open-circuit voltage OCV of the power battery.
Therefore, the invention provides an SOH correction method and system for an electric vehicle. The problem of inaccurate SOH estimated value of current electric automobile is solved, security and the intellectuality that electric automobile used can be improved.
The construction, features and functions of the present invention have been described in detail with reference to the embodiments shown in the drawings, but the present invention is not limited to the embodiments shown in the drawings, and all equivalent embodiments modified or modified by the spirit and scope of the present invention should be protected without departing from the spirit of the present invention.