Battery control method, device and vehicle for pure electric vehicle

Abstract

The present invention discloses a battery control method, device, and vehicle for a pure electric vehicle, including calculating the current battery pressure differential offset value v0; obtaining a base pressure differential limiting coefficient Kv as the current pressure differential limiting coefficient Kc; correcting the final pressure differential limiting coefficient Kf based on the battery pressure differential constant number n; determining the limited output power and final output power of the pure electric vehicle; and driving the system to respond to the output according to the final output power. The present invention accurately determines the battery pressure differential offset value based on the current battery state, linearly limits the power, and dynamically adjusts the limiting coefficient based on the battery condition after the limit. This can prevent excessive cell pressure differentials and power interruptions caused by improper battery use, thereby improving the driver's driving experience.

Description

Technical Field

[0001] The present invention belongs to the technical field of electric vehicles, and more particularly, relates to a battery control method, device and vehicle applicable to pure electric vehicles. Background Art

[0002] With the continuous development of new energy vehicle technology, pure electric vehicles have gained widespread recognition in domestic and international markets. As the energy source of pure electric vehicles, power batteries are subject to unstable characteristics such as explosion and fire, making battery protection particularly important.

[0003] A Chinese patent, publication number CN108001232B, entitled "Vehicle Fault Handling Method, Vehicle Controller, and Vehicle," discloses a technical solution that receives fault information from multiple electronic control units; determines the vehicle fault level based on the fault information and provides a fault indication, where the vehicle fault levels range from level 1 to level 6; and controls the vehicle system to enter a power-limited, degraded operating mode in the event of a level 2 fault (including a battery system fault), thereby effectively protecting the safety of various components and the entire vehicle. This solution, based on battery protection, results in instrument panel alarms and power interruptions, significantly reducing the driver's driving experience.

[0004] The Chinese patent with the publication number CN113296003A and the invention name is a power battery pressure difference early warning method and system, which discloses a technical solution: a power battery pressure difference early warning method, in which the discharge voltage parameters and battery operating temperature values ​​are obtained in real time when the power battery of an electric vehicle is in the discharge state. When the discharge voltage fluctuation voltage difference exceeds the set pressure difference threshold F and other conditions are met at the same time, it is determined that the power battery has a fault. After the power battery is determined to have a fault in the discharge state, a fault alarm signal is issued, and the power battery discharge is restricted at the same time. If the current discharge power is greater than the set discharge upper limit power, the discharge power is restricted to the set discharge threshold. If the current discharge power is lower than the set discharge lower limit power, the discharge power is restricted to the creeping power. This solution sets the alarm pressure difference to a fixed value, and does not take into account the situation where the battery pressure difference changes with the discharge current, and false alarms still exist. Similarly, if the power is directly reduced to a certain set power after a fault occurs, there is a risk of power loss.

[0005] In summary, the existing battery protection control methods applicable to pure electric vehicles have the following problems:

[0006] 1. Fault protection is only activated after a battery failure occurs, and the power limit is reduced to a lower set value. Instrument alarms and power interruptions occur, which greatly reduces the driver's driving experience.

[0007] 2. The normal voltage difference range of the battery varies under different conditions. Simply setting the voltage difference alarm threshold may result in false alarms. Summary of the Invention

[0008] In view of this, the present invention accurately determines the battery pressure difference offset value based on the current state of the battery, and provides a processing mechanism when the pressure difference is too large. It can linearly limit the power and dynamically adjust the limitation coefficient according to the battery condition after the limit. It can avoid the problem of excessive single-cell pressure difference and power interruption due to improper use of the battery, thereby improving the driver's driving experience.

[0009] To achieve the above objectives, a first aspect of the present invention provides a battery control method applicable to a pure electric vehicle, comprising:

[0010] S101: Calculate the current battery voltage difference offset value v0;

[0011] S102: Obtain the basic pressure difference limiting coefficient Kv as the current pressure difference limiting coefficient Kc;

[0012] S103: Correcting the battery pressure difference constant n to obtain a final pressure difference limiting coefficient Kf;

[0013] S104: Determine the limited output power and the final output power of the pure electric vehicle.

[0014] S105: The drive system responds to the output according to the final output power. Furthermore, the pure electric vehicle includes: an energy storage system, a vehicle control system and a drive system;

[0015] The battery management system in the energy storage system collects battery-related information in real time and sends it to the vehicle control system; the vehicle control system collects information such as the driving pedal in real time, combines the received battery system-related information to calculate the final output power, converts it into the corresponding target torque and sends it to the drive system; the motor controller in the drive system controls the motor output torque according to the target torque to complete the vehicle drive function.

[0016] Furthermore, step S101 includes: the battery management system collects the current maximum voltage difference, current battery discharge current and battery temperature of the single cell in real time, and sends them to the vehicle controller; the current maximum voltage difference of the battery is subtracted from the normal maximum voltage difference of the battery, and filtered, and the average value is taken, which is the current battery voltage difference offset value v0.

[0017] Furthermore, the normal maximum voltage difference is a maximum voltage difference value when the battery is in a healthy state, obtained by looking up a table based on the current battery discharge current and the battery temperature.

[0018] Further, step S102 includes: if the current battery pressure difference offset value v0 is less than the first pressure difference warning value v1, the basic pressure difference limiting coefficient Kv is 1; if the current battery pressure difference offset value v0 is greater than the first pressure difference warning value v1 and less than the second pressure difference warning value v2, the basic pressure difference limiting coefficient Kv is gradually reduced to the maximum limiting coefficient K1; if the current battery pressure difference offset value v0 is greater than or equal to the second pressure difference warning value v2, the basic pressure difference limiting coefficient Kv is kept equal to the maximum limiting coefficient K1 unchanged; the basic pressure difference limiting coefficient Kv is obtained as the current pressure difference limiting coefficient Kc.

[0019] Furthermore, the maximum limit coefficient K1 is the power limit coefficient when the vehicle system enters power limit degradation when the battery voltage difference is too large and an alarm is issued.

[0020] Further, step S103 includes: the initial value of the abnormal number of battery pressure differences n is 0; if the battery pressure difference offset value v0 detected in the current cycle is greater than or equal to the first pressure difference warning value v1, and less than the second pressure difference warning value v2, the abnormal number of battery pressure differences n is increased by 1; if the battery pressure difference offset value v0 is greater than or equal to the second pressure difference warning value v2, the abnormal number of battery pressure differences n is increased by 2; if the battery pressure difference offset value v0 is greater than 0, and less than the first pressure difference warning value v1, the abnormal number of battery pressure differences n is reduced by 1.

[0021] Furthermore, when the number of abnormal battery pressure differences n is greater than the abnormal pressure difference threshold N1, the pressure difference limiting coefficient adjustment is triggered, and the final pressure difference limiting coefficient Kf = the current pressure difference basic coefficient Kc * the correction coefficient c, where the correction coefficient c is less than 1. The final pressure difference limiting coefficient Kf becomes the new current pressure difference basic coefficient Kc, and the number of abnormal battery pressure differences n is reset to 0, and the calculation starts again.

[0022] Furthermore, the limited output power=the vehicle's current required power*the final pressure difference limiting coefficient Kf.

[0023] Furthermore, the limited output power is compared with other limiting conditions, such as the current maximum allowable discharge power of the battery, and the minimum value is taken as the output power of the vehicle. The minimum value is taken as the final output power of the vehicle.

[0024] Furthermore, the vehicle control system converts the final output power into a target torque and sends it to the motor controller to drive the vehicle.

[0025] A second aspect of the present invention provides a battery control device suitable for a pure electric vehicle, comprising: a calculation module: the calculation module is used to calculate a current battery voltage difference offset value v0;

[0026] Acquisition module: obtains the basic pressure difference limit coefficient Kv as the current pressure difference limit coefficient Kc;

[0027] Correction module: used to correct the battery pressure difference constant number n to obtain the final pressure difference limit coefficient Kf; determination module: used to determine the limited output power and final output power of the pure electric vehicle; output module: used to drive the system to respond to the output according to the final output power.

[0028] A third aspect of the present invention provides a vehicle, wherein the vehicle is provided with the battery control device according to the second aspect.

[0029] Compared with the existing technology, the battery control method described in the present invention has the following advantages: it can reasonably control the battery discharge process and selectively perform multiple corrections and adjustments according to the different degrees of battery voltage difference, so that the vehicle's output power is continuous and smooth, and there will be no vehicle power interruption, thereby effectively protecting the safety of single cells and the entire vehicle, and improving the safety and reliability of the vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of the battery protection control system

[0031] Figure 2 Flowchart of a battery control method according to an embodiment of the present invention

[0032] Figure 3 Logic diagram for adjusting the pressure difference limiting coefficient

[0033] Figure 4 Logic diagram for calculating final output power DETAILED DESCRIPTION

[0034] The present invention is further described below with reference to the following embodiments and accompanying drawings. This embodiment is based on the technical solution of the present invention and provides a detailed implementation method and specific operation process, but the scope of protection of the present invention is not limited to the following embodiments.

[0035] This embodiment describes the battery protection control method proposed according to the first aspect of the present invention.

[0036] like Figure 1 As shown, this method is applicable to a pure electric vehicle system consisting of an energy storage system 101, a vehicle control system 102, and a drive system 103. The battery management system in energy storage system 101 collects battery-related information in real time and transmits it to the vehicle control system. Vehicle control system 102 collects information such as the driving pedal in real time, combines it with the received battery system-related information, calculates the final output power, converts it into a corresponding target torque, and transmits it to the drive system. The motor controller in drive system 103 then controls the motor output torque based on the target torque to complete the vehicle drive function.

[0037] like Figure 2As shown, the battery protection control method includes the following steps:

[0038] In S101 , the current battery voltage difference offset value v0 is calculated.

[0039] Specifically, the battery management system collects the maximum voltage difference of the single cell, the current battery discharge current, and the battery temperature in real time, and sends it to the vehicle controller. In this embodiment, the CAN bus is used for data transmission. After the vehicle controller receives the maximum voltage difference, it can look up the table to obtain the normal maximum voltage difference value when the battery is in a healthy state based on the current battery discharge current and battery temperature. Generally, this data is obtained through bench testing. The normal maximum voltage difference obtained by looking up the table is subtracted from the received maximum voltage difference of the battery, and then filtered. Here, the average of the battery voltage difference offset values ​​of the 10 most recent cycles can be taken as the current battery voltage difference offset value v0.

[0040] In S102 , the basic pressure difference limiting coefficient Kv is obtained as the current pressure difference limiting coefficient Kc.

[0041] The vehicle controller can calculate the basic pressure difference limit coefficient based on the battery pressure difference offset value. The battery pressure difference offset value v0 is judged against the first pressure difference warning value v1 and the second pressure difference warning value v2. If the current battery pressure difference offset value v0 is less than the first pressure difference warning value v1, the basic pressure difference limit coefficient Kv is 1, that is, the output power is not limited. If the current battery pressure difference offset value v0 is greater than the first pressure difference warning value v1 and less than the second pressure difference warning value v2, the basic pressure difference limit coefficient Kv is gradually reduced to the maximum limit coefficient K1. Preferably, the maximum limit coefficient K1 is set to the power limit coefficient when the vehicle system enters power limit degradation when the battery pressure difference alarm is excessive, so that the output power is continuous and there is no interruption of vehicle power. If the current battery pressure difference offset value v0 is greater than or equal to the second pressure difference warning value v2, the basic pressure difference limit coefficient Kv is kept equal to the maximum limit coefficient K1. The basic pressure difference limit coefficient Kv is obtained as the current pressure difference limit coefficient Kc.

[0042] In S103 , a final pressure difference limiting coefficient Kf is obtained by performing correction according to the battery pressure difference abnormal number n.

[0043] Reference Figure 3This is a flowchart for calculating the pressure differential limit coefficient. The vehicle controller calculates the number of abnormal battery pressure differences, n, in real time, and sets n to an initial value of 0. If the battery pressure differential offset value, v0, detected in the current cycle is greater than or equal to the first pressure differential warning value, v1, and less than the second pressure differential warning value, v2, the number of abnormal battery pressure differences, n, increases by 1. If the battery pressure differential offset value, v0, is greater than or equal to the second pressure differential warning value, v2, the number of abnormal battery pressure differences, n, increases by 2. If the battery pressure differential offset value, v0, is greater than 0 and less than the first pressure differential warning value, v1, the number of abnormal battery pressure differences, n, decreases by 1. When the number of abnormal battery pressure differences, n, exceeds the pressure differential threshold, N1, the number of abnormal battery pressure differences, n, is restored to 0, triggering adjustment of the pressure differential limit coefficient. The current pressure differential base coefficient, Kv, is multiplied by the correction coefficient, c, to obtain the adjusted final pressure differential limit coefficient, Kf, where the correction coefficient, c, is less than 1.

[0044] Furthermore, after adjusting the pressure difference limiting coefficient, the number of battery pressure difference abnormalities is calculated again. When n is greater than the pressure difference abnormal threshold N1, n is restored to 0, triggering the pressure difference limiting coefficient adjustment. The adjusted pressure difference limiting coefficient is equal to the pressure difference number after the previous adjustment multiplied by the correction coefficient.

[0045] In S104 , the limited output power and the final output power are calculated.

[0046] Reference Figure 4 To calculate the final output power flow chart, the limited demand power is equal to the vehicle's current demand power multiplied by the final pressure difference limit coefficient, where the vehicle's current demand power is calculated based on factors such as the driver's pedal opening, vehicle status, and motor characteristics.

[0047] Furthermore, the limited required power is compared with other limiting conditions, such as the current maximum allowable discharge power of the battery, and the minimum value is taken as the final output power.

[0048] In S105 , the drive system responds to the output.

[0049] The vehicle control system sends commands to control the drive system based on the final output power. In this embodiment, the final output power is converted into a target torque and sent to the motor controller, where the target torque = 9550 * final output power / motor speed. The motor controller controls the motor to drive the vehicle.

[0050] A second aspect of the present invention provides a battery control device suitable for a pure electric vehicle, comprising: a calculation module: the calculation module is used to calculate a current battery voltage difference offset value v0;

[0051] Acquisition module: obtains the basic pressure difference limit coefficient Kv as the current pressure difference limit coefficient Kc;

[0052] Correction module: used to correct the battery pressure difference constant number n to obtain the final pressure difference limit coefficient Kf; determination module: used to determine the limited output power and final output power of the pure electric vehicle; output module: used to drive the system to respond to the output according to the final output power.

[0053] A third aspect of the present invention provides a vehicle, wherein the vehicle is provided with the battery control device according to the second aspect.

Claims

1. A battery control method for a pure electric vehicle, characterized in that: include, S101: Calculate the current battery voltage differential offset value v0: The battery management system collects the current maximum voltage differential, current battery discharge current, and battery temperature of the single battery in real time and sends them to the vehicle controller. The current maximum voltage differential of the battery is subtracted from the normal maximum voltage differential of the battery, and the average value is filtered to obtain the current battery voltage differential offset value v0. S102: If the current battery pressure difference offset value v0 is less than the first pressure difference warning value v1, the basic pressure difference limiting coefficient Kv is 1; if the current battery pressure difference offset value v0 is greater than the first pressure difference warning value v1 and less than the second pressure difference warning value v2, the basic pressure difference limiting coefficient Kv is gradually reduced to the maximum limiting coefficient K1; if the current battery pressure difference offset value v0 is greater than or equal to the second pressure difference warning value v2, the basic pressure difference limiting coefficient Kv is maintained equal to the maximum limiting coefficient K1. Get the basic pressure difference limiting coefficient Kv as the current pressure difference limiting coefficient Kc; S103: Correct the final pressure difference limiting coefficient Kf according to the abnormal number of battery pressure differences n; the initial value of the abnormal number of battery pressure differences n is 0. If it is detected in the current cycle that the current battery pressure difference offset value v0 is greater than or equal to the first pressure difference warning value v1 and less than the second pressure difference warning value v2, the abnormal number of battery pressure differences n is increased by 1; if the current battery pressure difference offset value v0 is greater than or equal to the second pressure difference warning value v2, the abnormal number of battery pressure differences n is increased by 2; if the current battery pressure difference offset value v0 is greater than 0 and less than the first pressure difference warning value v1, the abnormal number of battery pressure differences n is reduced by 1; when the abnormal number of battery pressure differences n is greater than the abnormal pressure difference threshold N1, the pressure difference limiting coefficient is adjusted, and the final pressure difference limiting coefficient Kf = the current pressure difference limiting coefficient Kc * the correction coefficient c, where the correction coefficient c is less than 1, the final pressure difference limiting coefficient Kf becomes the new current pressure difference limiting coefficient Kc, the abnormal number of battery pressure differences n is reset to 0, and the calculation is restarted; S104: Determine the limited output power and the final output power of the pure electric vehicle; S105: The driving system responds to output according to the final output power.

2. The battery control method according to claim 1, wherein: The pure electric vehicle includes: an energy storage system, a vehicle control system and a drive system; The battery management system in the energy storage system collects battery-related information in real time and sends it to the vehicle control system; the vehicle control system collects driving pedal information in real time, calculates the final output power based on the received battery system information, converts it into the corresponding target torque and sends it to the drive system; the motor controller in the drive system controls the motor output torque according to the target torque to complete the vehicle drive function.

3. The battery control method according to claim 2, wherein: The normal maximum voltage difference is a maximum voltage difference value when the battery is in a healthy state, obtained by looking up a table based on the current battery discharge current and the battery temperature.

4. The battery control method according to claim 2, wherein: The maximum limit coefficient K1 is the power limit coefficient when the vehicle system enters power limit degradation when the battery voltage difference is too large and an alarm is triggered.

5. The battery control method according to claim 2, wherein: S104 includes: The limited output power = the vehicle's current required power * the final pressure difference limiting coefficient Kf.

6. The battery control method according to claim 5, wherein: S104 includes: The limited output power is compared with the current maximum allowable discharge power of the battery, and the minimum value is taken as the final output power of the vehicle.

7. The battery control method according to claim 2, wherein: S105 includes: The vehicle control system converts the final output power into a target torque and sends the target torque to the motor controller to drive the vehicle.

8. A battery control device for a pure electric vehicle, characterized in that: The device is used to implement the control method according to any one of claims 1 to 7, include, Calculation module: used to calculate the current battery voltage difference offset value v0; Acquisition module: obtains the basic pressure difference limit coefficient Kv as the current pressure difference limit coefficient Kc; Correction module: used to correct the battery pressure difference constant number n to obtain the final pressure difference limit coefficient Kf; Determination module: used to determine the limited output power and the final output power of the pure electric vehicle; Output module: used to drive the system to output according to the final output power response.

9. A vehicle, characterized in that: The vehicle is provided with the battery control device according to claim 8.

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