Control method and system for ensuring regular correction of SOC (State of Charge) of power battery and vehicle

Abstract

The invention discloses a control method and system for guaranteeing regular correction of the SOC of a power battery and a vehicle, and the control method comprises the steps: generating a first indication signal when a BMS monitors that the power battery is not fully charged for a long time, and transmitting the first indication signal to a VCU; the BMS judges the real-time charging state of the power battery when receiving an instruction that the charging target SOC sent by the VCU is a preset full charging threshold value, generates a second indication signal when the power battery is in charging and the current SOC reaches the preset full charging threshold value, and sends the second indication signal to the VCU; and when the VCU receives the first indication signal, the charging target SOC is set to be a preset full charge threshold value, when the VCU receives the second indication signal, the charging target SOC is set to be an SOC target value selected by a user, and an instruction is sent to the BMS. Forced full charge can be realized through interaction of the BMS and the VCU so as to carry out SOC correction.

Description

Technical Field

[0001] The present invention belongs to the technical field of power battery charging for new energy vehicles, and specifically relates to a control method, system and vehicle for ensuring regular correction of the SOC of a power battery. Background Art

[0002] Currently, new energy vehicles utilize lithium-ion batteries, which are categorized by cathode material into two main types: ternary lithium batteries and lithium iron phosphate batteries. Ternary lithium batteries offer higher specific capacity, linear cell voltage variation, and excellent low-temperature performance. However, they are associated with higher production costs and poor safety performance, raising concerns among users about the risk of thermal runaway. Lithium iron phosphate batteries, with their lower raw material costs, safer charge and discharge performance, and longer cycle life, are gaining popularity among users, and their share of the new energy vehicle market is increasing.

[0003] With the increasing adoption of lithium iron phosphate (LFP) batteries, the inherent poor SOC estimation accuracy has received increasing attention. Despite continuous optimization and improvement of BMS strategies for LFP battery SOC estimation, the primary SOC correction strategy still relies on full charging and discharging of the power battery (full-charge correction is an existing technology). However, because vehicles feature a target SOC setting function, some users habitually set (or select) a target SOC lower than 100% (e.g., 90%). This results in the power battery being undercharged for extended periods, preventing SOC correction. This inevitably leads to significant SOC estimation deviations, necessitating regular full charging of the vehicle's power battery (i.e., regularly filling the power battery to capacity) for SOC correction. This is particularly true for plug-in hybrid vehicles, which have lower power battery capacities and experience prolonged engine startup for recharging. This can easily lead to significant SOC deviations, increasing the risk of power throttling or even power outages during driving. This heightens the need for regular full charging of the power battery to correct the SOC. Typically, when a periodic full-charge correction is necessary, the BMS will prompt the user through the vehicle computer to fully charge the battery next time (i.e., a full-charge reminder). After seeing the full-charge reminder, the user manually sets the target SOC to 100% the next time they charge, thereby implementing the full-charge correction. However, if the display device malfunctions and the full-charge reminder is not displayed, the user will not be aware of the need for a full charge. The BMS will still charge according to the user's previously set target SOC (e.g., 80%), and the full-charge correction will not be made in a timely manner, resulting in an increase in the accumulated SOC error. Therefore, current periodic full-charge correction technology is highly dependent on the user and cannot guarantee the periodic full-charge correction of the power battery SOC. Summary of the Invention

[0004] The purpose of the present invention is to provide a control method, system and vehicle that ensure the regular correction of the SOC of the power battery. Through the coordinated control of the BMS and the VCU, the regular full charging of the power battery SOC is automatically executed without relying on manual setting operations by the user, and the regular full charging of the vehicle's power battery and the correction of the SOC are guaranteed.

[0005] In a first aspect, the present invention provides a control method for ensuring regular correction of the SOC of a power battery, comprising: When the BMS detects that the power battery is not fully charged for a long time, it generates a first indication signal and sends the first indication signal to the VCU; when the BMS receives the charging target SOC instruction from the VCU that is the preset full charge threshold, it determines the real-time charging status of the power battery. When the power battery is charging and the current SOC reaches the preset full charge threshold (indicating that the power battery is fully charged and the SOC correction has been performed), it generates a second indication signal and sends the second indication signal to the VCU.

[0006] The VCU adjusts the charging target SOC of the power battery based on the received indication signal; if the received indication signal is the first indication signal, the charging target SOC is set to the preset full charge threshold, and an instruction that the charging target SOC is the preset full charge threshold is sent to the BMS; if the received indication signal is the second indication signal, the charging target SOC is set to the SOC target value selected by the user, and an instruction that the charging target SOC is the SOC target value selected by the user is sent to the BMS.

[0007] Preferably, the control method for ensuring regular correction of the power battery SOC further includes: The BMS sends the first indication signal or the second indication signal to the vehicle computer. When the vehicle computer receives the first indication signal, it issues a prompt and exits the prompt after a first preset time or after receiving a user instruction to close the prompt.

[0008] Preferably, the first indication signal is a long-time not fully charged flag 1, the second indication signal is a long-time not fully charged flag 0, and the preset full charge threshold is 100%.

[0009] Preferably, if condition one or condition two is met, it means that the power battery is not fully charged for a long time; wherein, Condition 1: The cumulative external charging capacity is greater than or equal to N1*Q; N1 represents the preset multiple threshold, and Q represents the rated capacity of the power battery; Condition 2: The cumulative number of external charging times is greater than or equal to N2; N2 represents a preset number threshold, N2>N1.

[0010] Preferably, the cumulative number of external charging times and the cumulative capacity of external charging are obtained by the following steps: S11. Determine whether the power battery charging state is charging. If yes, execute S12; otherwise, end.

[0011] S12: Determine whether the power battery charging state is complete. If so, execute S13; otherwise, continue to execute S12.

[0012] S13: Determine whether the current SOC of the power battery has reached a preset full charge threshold. If yes, execute S14; otherwise, execute S15.

[0013] S14 , setting the cumulative number of external charging times to 0 (i.e., clearing the cumulative number of external charging times to zero), setting the cumulative capacity of this external charging to 0 (i.e., clearing the cumulative capacity of the external charging to zero), and then ending.

[0014] S15: Increase the cumulative number of external charging times by 1, and use the sum of the current external charging capacity and the previous external charging cumulative capacity as the current external charging cumulative capacity, and then end. The initial value of the cumulative number of external charging times is 0, and the initial value of the external charging cumulative capacity is 0.

[0015] Preferably, the preset multiple threshold N1=6, and the preset number threshold N2=10.

[0016] Preferably, the preset multiple threshold N1 is obtained by: The power battery is subjected to multiple shallow charge and shallow discharge tests, and the charging capacity is accumulated until the deviation between the measured SOC value of the power battery and the actual SOC value is greater than or equal to 10%.

[0017] The preset multiple threshold N1 is calculated using the formula: N1=Roundup (Q1 / Q).

[0018] Among them, Q1 represents the cumulative value of charging capacity obtained by accumulating charging capacity in multiple shallow charge and shallow discharge tests, Roundup () represents a rounding-up function, Roundup (Q1 / Q) represents the integer rounded up to Q1 / Q, and the shallow charge and shallow discharge test refers to a charge and discharge test in which the SOC is less than 100% when charging is completed and the SOC is greater than 0 when discharging is completed.

[0019] In a second aspect, the present invention provides a control system for ensuring regular correction of a power battery's SOC, comprising a battery management system (BMS) and a vehicle control unit (VCU), the VCU being communicatively connected to the BMS. The BMS is configured to: upon detecting that the power battery has been undercharged for an extended period, generate a first indication signal and transmit the first indication signal to the VCU; then, upon receiving an instruction from the VCU indicating that the target charging SOC is a preset full-charge threshold, determine the real-time charging state of the power battery; and when the power battery is charging and the current SOC reaches a preset full-charge threshold (indicating that the power battery is fully charged and has been corrected), generate a second indication signal and transmit the second indication signal to the VCU. The VCU is configured to: adjust the target charging SOC of the power battery based on the received indication signal; if the received indication signal is the first indication signal, set the target charging SOC to the preset full-charge threshold, and transmit an instruction indicating that the target charging SOC is the preset full-charge threshold to the BMS; if the received indication signal is the second indication signal, set the target charging SOC to a user-selected target SOC value, and transmit an instruction indicating that the target charging SOC is the user-selected target SOC value to the BMS.

[0020] Preferably, the control system for ensuring regular correction of the power battery SOC also includes a vehicle computer, which is communicatively connected to the BMS; the BMS sends the first indication signal or the second indication signal to the vehicle computer, and the vehicle computer issues a prompt when receiving the first indication signal, and exits the prompt after a first preset time or after receiving a user's instruction to close the prompt.

[0021] In a third aspect, the present invention provides a vehicle comprising the above-mentioned control system for ensuring regular correction of the SOC of the power battery.

[0022] The present invention has the following effects: (1) When the power battery is not fully charged for a long time, the coordinated control of BMS and VCU realizes the automatic execution of full charging, rather than relying on the user's manual setting operation. The specific process is: BMS detects the state of not fully charged → generates the first indication signal → actively triggers VCU intervention → VCU forces the charging target SOC to be set to the preset full charge threshold → BMS detects that the SOC reaches the preset full charge threshold during charging → generates the second indication signal → VCU automatically restores the SOC target value selected by the user. It does not rely on the system to send a full charge prompt message to the user, and does not require the user to manually adjust the charging target SOC. Instead, it dynamically adjusts the charging target SOC through the VCU, and forces a full charge cycle to be completed during the current charging or the next charging (excluding the special case where the user actively draws the gun), ensuring the inevitable execution of SOC correction, solving the problem of SOC cumulative error caused by the user ignoring the full charge prompt and not manually adjusting the charging target SOC, and realizing the automatic regular full charging of the vehicle's power battery, ensuring the regular correction of the power battery SOC, and reducing the SOC error.

[0023] (2) It does not rely on the system to issue a full charge prompt to the user. In the event that the display device fails to display the full charge prompt or the user terminal fails to connect to the vehicle, the coordinated control of the BMS and VCU can still automatically execute full charge during the current charge or the next charge, thus avoiding the continued increase of the SOC cumulative error, improving the effectiveness and reliability of the control method, and thus improving the safety of the entire vehicle.

[0024] (3) Full charging is automatically executed through the coordinated control of BMS and VCU. When charging, the user only needs to plug in the gun. The user does not need to open the APP on the user terminal to set the full charging target SOC. The user does not need to open the car door to enter the car and set the full charging target SOC on the car computer. This improves the convenience of regular full charging operations and enhances the user experience.

[0025] (4) Full charging is automatically executed through the coordinated control of BMS and VCU. There is no need to add / change hardware, only software needs to be modified. While achieving regular full charging of the vehicle's power battery, it also avoids increasing hardware costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a flowchart of the execution of the BMS in the control method for ensuring regular correction of the power battery SOC according to an embodiment of the present invention.

[0027] Figure 2 This is a flowchart of the execution of the VCU in the control method for ensuring regular correction of the power battery SOC according to an embodiment of the present invention.

[0028] Figure 3 This is a flowchart of the execution of the vehicle computer in the control method for ensuring regular correction of the power battery SOC according to an embodiment of the present invention.

[0029] Figure 4 This is a flow chart for obtaining the cumulative number of external charging times and the cumulative capacity of external charging in an embodiment of the present invention. DETAILED DESCRIPTION

[0030] In order to enable a more detailed understanding of the features and technical contents of the embodiments of the present invention, the implementation of the embodiments of the present invention is described in detail below with reference to the accompanying drawings. The accompanying drawings are for reference only and are not intended to limit the embodiments of the present invention.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention pertains. The terms used herein are for the purpose of describing embodiments of the present invention only and are not intended to limit the present invention.

[0032] In the following description, reference is made to “some embodiments”, which describes a subset of all possible embodiments, but it will be understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0033] In the embodiment of the present invention, the control system for ensuring the regular correction of the power battery SOC includes a BMS (i.e., battery management system) and a VCU (i.e., vehicle control unit), and the VCU is in communication with the BMS. In the embodiment of the present invention, the control method for ensuring the regular correction of the power battery SOC includes the steps executed by the BMS (see Figure 1 ) and the steps performed by the VCU (see Figure 2 ).

[0034] like Figure 1 As shown, the BMS is configured to perform the following steps: S21. Determine whether the power battery is not fully charged for a long time. If yes, execute S22; otherwise, end.

[0035] In some embodiments, if condition 1 or condition 2 is met, it means that the power battery has not been fully charged for a long time. Condition 1: The cumulative external charging capacity is greater than or equal to N1*Q. N1 represents the preset multiple threshold, and Q represents the rated capacity of the power battery.

[0036] In some embodiments, the preset multiple threshold N1 is obtained as follows: First, the power battery is subjected to multiple shallow charge and shallow discharge tests, and the charging capacity is accumulated until the deviation between the measured SOC value of the power battery and the actual SOC value is greater than or equal to 10%.

[0037] Then, the preset multiple threshold N1 is calculated using the formula: N1=Roundup (Q1 / Q).

[0038] Among them, Q1 represents the cumulative value of charging capacity obtained by accumulating charging capacity in multiple shallow charge and shallow discharge tests, Roundup () represents a rounding-up function, Roundup (Q1 / Q) represents the integer rounded up to Q1 / Q, and the shallow charge and shallow discharge test refers to a charge and discharge test in which the SOC is less than 100% when charging is completed and the SOC is greater than 0 when discharging is completed.

[0039] As an example, here Q1=500Ah, Q=90Ah, then N1=6.

[0040] Condition 2: The cumulative number of plug-in charging times is greater than or equal to N2. N2 represents a preset number threshold, N2>N1. As an example, here N2=10.

[0041] In some embodiments, the cumulative number of plug-in charging times and the cumulative capacity of plug-in charging are calculated by the following steps (see Figure 4 )get: S11. Determine whether the power battery charging state is charging. If yes, execute S12; otherwise, end.

[0042] S12: Determine whether the power battery charging state is complete. If so, execute S13; otherwise, continue to execute S12.

[0043] S13: Determine whether the current SOC of the power battery is 100%. If so, execute S14; otherwise, execute S15.

[0044] S14 , setting the cumulative number of external charging times to 0 (i.e., clearing the cumulative number of external charging times to zero), setting the cumulative capacity of this external charging to 0 (i.e., clearing the cumulative capacity of the external charging to zero), and then ending.

[0045] S15. Increase the cumulative number of external charging times by 1, and use the sum of the current external charging capacity and the previous external charging capacity as the current external charging capacity, and then end. The initial value of the cumulative number of external charging times is 0, and the initial value of the external charging capacity is 0. For example, if the first external charging is completed but not fully charged, the cumulative number of external charging times is 1 (i.e., 1 + 0 = 1), and the first external charging capacity is equal to the first external charging capacity + 0. If the second external charging is completed but not fully charged, the cumulative number of external charging times is 2 (i.e., 1 + 1 = 2), and the second external charging capacity is equal to the second external charging capacity + the first external charging capacity, and so on.

[0046] By judging whether the full charge period has arrived based on the cumulative number of external charging times or the cumulative capacity of external charging, without considering the time between the current time point and the time point of the most recent full charge, misjudgment due to the introduction of vehicle usage frequency is avoided (for example, the vehicle is used frequently and the cumulative capacity of external charging is already greater than N1*Q, but because the time length does not reach the predetermined time length, it is not determined that the power battery has not been fully charged for a long time). The conditions are set reasonably, thereby avoiding the inability to correct the SOC of the power battery due to being in an uncharged state for a long time, and avoiding excessive deviation in the SOC estimation.

[0047] S22: Generate a first instruction signal, and send the first instruction signal to the VCU and the vehicle computer, and then execute S23.

[0048] In some embodiments, the first indication signal is a long time not full flag 1. Step S22 may be: setting the long time not full flag to 1, and sending the long time not full flag 1 to the VCU and the vehicle computer, and then executing S23.

[0049] S23: Determine whether the charging target SOC received from the VCU is the preset full charge threshold. If so, execute S24; otherwise, continue to execute S23. In some embodiments, the preset full charge threshold is 100%.

[0050] S24: Determine whether the power battery charging state is charging. If yes, execute S25; otherwise, end.

[0051] S25. Determine whether the current SOC of the power battery is at a preset full charge threshold. If so (indicating that the power battery is fully charged and the SOC correction has been performed), execute S26; otherwise, return to execute S24.

[0052] S26: Generate a second instruction signal, and send the second instruction signal to the VCU and the vehicle computer, and then end.

[0053] In some embodiments, the second indication signal is a long time not full flag 0. Step S26 may be: setting the long time not full flag to 0, and sending the long time not full flag 0 to the VCU and the vehicle computer, and then ending.

[0054] like Figure 2 As shown, the VCU is configured to perform the following steps: S31. Determine whether a first instruction signal is received. If yes, execute S32; otherwise, execute S34.

[0055] S32 , setting the charging target SOC to a preset full-charge threshold, and sending a charging target SOC to the preset full-charge threshold instruction to the BMS, and then executing S33 .

[0056] S33. Determine whether the second instruction signal is received. If yes, execute S34; otherwise, continue to execute S33.

[0057] S34: Set the charging target SOC to the user-selected SOC target value, and send a command indicating that the charging target SOC is the user-selected SOC target value to the BMS, and then end. This avoids the user having to select the charging target SOC again, and the full charge correction in the present invention does not impose additional operational burden on the user.

[0058] In the case that the power battery is not fully charged for a long time (indicating that the vehicle's power battery needs to be fully charged at the regular time), the interaction between the BMS and the VCU is used to force full charging during the current (or subsequent) charging to correct the SOC. This achieves regular full charging of the vehicle's power battery, ensures regular correction of the power battery SOC, and reduces SOC errors.

[0059] In some embodiments, the control system for ensuring the regular correction of the power battery SOC further comprises a vehicle computer, which is in communication with the BMS. In some embodiments, the control method for ensuring the regular correction of the power battery SOC further comprises steps executed by the vehicle computer (see Figure 3 ).

[0060] like Figure 3 As shown, the vehicle computer performs the following steps: S41. Determine whether a first instruction signal is received. If yes, execute S42; otherwise, end.

[0061] S42, a pop-up window prompts "Full charge correction", and then executes S43.

[0062] S43: Determine whether the duration reaches a first preset time. If yes, execute S45; otherwise, execute S44.

[0063] S44: Determine whether a user instruction to close the pop-up window is received. If yes, execute S45; otherwise, return to execute S43.

[0064] S45. Exit the pop-up prompt and then end.

[0065] In some embodiments, the first preset time is 15 seconds, which takes into account the time from when the driver's seat of the vehicle is occupied to when the vehicle enters the driving gear, so that there is enough time to remind the user of "full charge correction".

[0066] After receiving the first indication signal (i.e., the "Long Time Undercharge Flag 1"), the vehicle computer displays a pop-up window with a "Full Charge Correction" prompt, reminding the user that the vehicle's current or next charging time is full. This prevents users from failing to recognize that the displayed battery level differs significantly from the actual battery level after a long period of undercharging, thereby reducing the risk of power interruption during driving. After the pop-up prompt persists for the first preset time or the user actively closes it, the full charge correction prompt will no longer be displayed during the current vehicle operation, preventing the pop-up prompt from interfering with the user's normal vehicle use and improving the user experience.

[0067] In addition, an embodiment of the present invention further provides a vehicle, which includes the above-mentioned control system for ensuring regular correction of the SOC of the power battery.

[0068] The above description is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with this technical field within the technical scope disclosed in the present invention should be covered by the scope of protection of the present invention.

Claims

1. A control method for ensuring regular correction of the SOC of a power battery, characterized in that: include: When the BMS detects that the power battery is not fully charged for a long time, it generates a first indication signal and sends it to the VCU; When the BMS receives the instruction from the VCU that the charging target SOC is the preset full charge threshold, it determines the real-time charging status of the power battery. When the power battery is charging and the current SOC reaches the preset full charge threshold, it generates a second indication signal and sends it to the VCU. The VCU adjusts the charging target SOC of the power battery based on the received indication signal and sends it to the BMS; if the received indication signal is the first indication signal, the charging target SOC is set to the preset full charge threshold; if the received indication signal is the second indication signal, the charging target SOC is set to the SOC target value selected by the user.

2. The control method for ensuring regular correction of the power battery SOC according to claim 1, characterized in that: Also includes: The BMS sends the first indication signal or the second indication signal to the vehicle computer. When the vehicle computer receives the first indication signal, it issues a prompt and exits the prompt after a first preset time or after receiving a user instruction to close the prompt.

3. The control method for ensuring regular correction of the power battery SOC according to claim 2, characterized in that: The first indication signal is a long-time not fully charged flag 1, the second indication signal is a long-time not fully charged flag 0, and the preset full charge threshold is 100%.

4. The control method for ensuring periodic correction of the power battery SOC according to any one of claims 1 to 3, characterized in that: If condition 1 or condition 2 is met, it means that the power battery has not been fully charged for a long time; Condition 1: The cumulative external charging capacity is greater than or equal to N1*Q; N1 represents the preset multiple threshold, and Q represents the rated capacity of the power battery; Condition 2: The cumulative number of external charging times is greater than or equal to N2; N2 represents a preset number threshold, N2>N1.

5. The control method for ensuring regular correction of the power battery SOC according to claim 4, characterized in that: The cumulative number of external plug-in charging times and the cumulative external plug-in charging capacity are obtained by the following steps: S11, determining whether the power battery charging state is charging, if yes, executing S12, otherwise ending; S12, determining whether the power battery charging state is charging completed, if so, executing S13, otherwise continuing to execute S12; S13, determining whether the current SOC of the power battery has reached a preset full charge threshold; if so, executing S14; otherwise, executing S15; S14, set the cumulative number of external plug-in charging to 0, set the cumulative capacity of this external plug-in charging to 0, and then end; S15: Increase the cumulative number of external plug-in charging times by 1, and take the sum of the current plug-in charging capacity and the previous external plug-in charging cumulative capacity as the current external plug-in charging cumulative capacity, and then end; wherein, the initial value of the cumulative number of external plug-in charging times is 0, and the initial value of the external plug-in charging cumulative capacity is 0.

6. The control method for ensuring regular correction of the power battery SOC according to claim 4, characterized in that: The preset multiple threshold N1=6, and the preset number threshold N2=10.

7. The control method for ensuring regular correction of the power battery SOC according to claim 4, characterized in that: The preset multiple threshold N1 is obtained as follows: Perform shallow charge and discharge tests on the power battery multiple times, and accumulate the charge capacity until the deviation between the measured SOC value and the actual SOC value of the power battery is greater than or equal to 10%. Use the formula: N1=Roundup(Q1 / Q) to calculate the preset multiple threshold N1; Among them, Q1 represents the cumulative value of charging capacity obtained by accumulating charging capacity in multiple shallow charge and shallow discharge tests, Roundup() represents an upward rounding function, and the shallow charge and shallow discharge test refers to a charging and discharging test in which the SOC is less than 100% when charging is completed and the SOC is greater than 0 when discharging is completed.

8. A control system for ensuring regular correction of the power battery SOC, characterized by: Including BMS and VCU, VCU and BMS communication connection; The BMS is configured to: generate a first indication signal and send it to the VCU when it detects that the power battery is not fully charged for a long time; upon receiving an instruction from the VCU that the charging target SOC is a preset full charge threshold, determine the real-time charging state of the power battery; and when the power battery is being charged and the current SOC reaches the preset full charge threshold, generate a second indication signal and send it to the VCU; The VCU is configured to: adjust the charging target SOC of the power battery based on the received indication signal and send it to the BMS; wherein, if the received indication signal is a first indication signal, the charging target SOC is set to a preset full charge threshold; if the received indication signal is a second indication signal, the charging target SOC is set to an SOC target value selected by the user.

9. The control system for ensuring regular correction of the power battery SOC according to claim 8, characterized in that: It also includes a vehicle computer, which is communicatively connected to the BMS. The BMS sends a first indication signal or a second indication signal to the vehicle computer. When the vehicle computer receives the first indication signal, it gives a prompt, and exits the prompt after a first preset time or after receiving a user's instruction to close the prompt.

10. A vehicle, characterized in that: It includes a control system for ensuring regular correction of the power battery SOC as described in claim 8 or 9.

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