A double-dimension aging-based electric bicycle battery charging upper limit control method

Abstract

The present application relates to the technical field of battery charging, in particular to a charging upper limit control method for electric bicycle battery based on double-dimension aging. The method comprises the following steps: S1, parameter acquisition and configuration: obtaining SOH and Y0, and pre-storing a set of configurable threshold parameters in the system; S2, obtaining the charging upper limit based on the cycle aging dimension; S3, obtaining the charging upper limit based on the calendar aging dimension; S4, comparing to obtain the final charging upper limit; comparing the two upper limit values calculated by S2 and S3, and taking the minimum value as the final actual executed charging upper limit; S5, charging protection: controlling the charging process, and stopping charging when the battery capacity reaches the current maximum available capacity x U_final. The double-dimension independent judgment is combined with the most stringent principle, and the SOC display recalculation is matched, thereby forming a complete and fine battery full life cycle management scheme.

Description

Technical Field

[0001] This invention relates to the field of battery charging technology, specifically a method for controlling the upper limit of electric bicycle battery charging based on two-dimensional aging. Background Technology

[0002] Currently, electric bicycles widely use lithium-ion batteries as their power source, and their battery management system (BMS) is crucial for ensuring battery safety and extending battery life. However, existing BMS charging control strategies generally have the following shortcomings: Single dimension: Most control strategies only protect based on voltage, temperature or a single cycle number, failing to treat the two core mechanisms that lead to battery performance degradation—cycle aging caused by charge-discharge cycles and calendar aging caused by the passage of time—as independent dimensions for parallel judgment and control.

[0003] Rigid protection: Most charging protection measures are single-point triggered, such as directly cutting off charging after reaching a certain SOH threshold. They lack a smooth transition mechanism, which leads to a sudden and significant reduction in battery life at the end of the battery's life. This results in a poor user experience and can easily cause range anxiety.

[0004] Poor adaptability: Key control thresholds, such as SOH threshold and age threshold, are mostly fixed values, which cannot be adapted to different chemical systems, such as the aging characteristics of ternary lithium and lithium iron phosphate batteries, thus limiting the versatility of the method.

[0005] There are potential safety hazards: There is a lack of targeted protection for "high-age, low-cycle" batteries, that is, batteries with severe calendar aging but few cycle counts, and the safety risks caused by the natural degradation of materials are ignored.

[0006] Display logic lag: When the charging limit is artificially reduced, the SOC display is still based on the factory capacity, which causes the SOC to jump or be displayed inaccurately, which can easily mislead users. Summary of the Invention

[0007] To overcome the shortcomings of existing technologies, this invention provides a method for controlling the upper limit of electric bicycle battery charging based on dual-dimensional aging. This method is based on independent dual-dimensional judgment, adopts the most stringent limit, has a configurable threshold, includes a safety fallback mechanism, and simultaneously optimizes the SOC display logic.

[0008] To achieve the above objectives, a method for controlling the upper limit of electric bicycle battery charging based on two-dimensional aging is designed, including the following steps: S1, Parameter Acquisition and Configuration: Obtain the current battery health status SOH and the usage time Y0, and pre-store a set of configurable threshold parameters in the system, including cycle aging start threshold, cycle aging end threshold, calendar aging start time, and calendar aging end time. S2. Obtain the charging upper limit based on the cycling aging dimension: According to the ratio relationship between the state of health (SOH) of the battery, the cycling aging start threshold, and the cycling aging end threshold, obtain the charging upper limit U_cycle of the cycling aging dimension; S3. Obtain the charging upper limit based on the calendar aging dimension: According to the ratio relationship between the current used duration, the calendar aging start duration, and the calendar aging end duration, obtain the charging upper limit U_time of the calendar aging dimension; S4. Compare to obtain the final charging upper limit: Compare the two upper limit values calculated in S2 and S3, and take the minimum value as the final actual implemented charging upper limit U_final = min(U_cycle, U_time); S5. Charging protection: The BMS controls the charging process based on U_final. When the battery charge reaches the current maximum available capacity × U_final, the charging stops.

[0009] The specific method for obtaining the state of health (SOH) of the current battery in step S1 is as follows: S11. The BMS collects the voltage, current, and temperature data of the battery in real time; S12. Estimate the current maximum available capacity of the battery based on the collected data; S13. Obtain the state of health SOH = current maximum available capacity / factory rated capacity × 100%.

[0010] In step S1, record or read the factory time of the battery and calculate the used duration.

[0011] In step S1, the cycling aging start threshold is set to 70% - 80% of SOH; the cycling aging end threshold is set to 50% - 60% of SOH; the calendar aging start duration is set to 5 - 8 years; the calendar aging end duration is set to 8 - 10 years.

[0012] In step S2, when SOH > the cycling aging start threshold, U_cycle = 100%; when the cycling aging end threshold < SOH ≤ the cycling aging start threshold, ; when SOH ≤ the cycling aging end threshold, U_cycle = 0%.

[0013] In step S3, when the used duration < the calendar aging start duration, U_time = 100%; when the calendar aging start duration ≤ the used duration < the calendar aging end duration, ; when the used duration ≥ the calendar aging end duration, U_time = 0%.

[0014] In step S5, the BMS simultaneously recalculates and displays the SOC based on the current maximum available capacity as 100%. The displayed SOC value is calculated as (current remaining power / current maximum available capacity) × 100%.

[0015] It also includes step S6, forced protection: at any time, if U_final = 0%, the BMS triggers forced protection: cuts off the charging MOSFET and prohibits any charging behavior.

[0016] In step S6, after the forced protection is triggered, the battery status is reported to the host computer or instrument through the communication interface to prompt the user to replace it; or the battery status is reported through the power indicator light board to prompt the user to replace it.

[0017] Compared with existing technologies, this invention combines independent judgment in two dimensions with the most stringent principle, and adds SOC display recalculation to form a complete and refined battery life cycle management solution, which has the following beneficial effects: 1. Significantly enhanced safety: Through dual-dimensional parallel monitoring and the adoption of the most stringent principles, it effectively covers two types of failure risks: cycle aging and calendar aging. In particular, it can force the disposal of batteries with safety hazards such as "high age, low cycle life". 2. Extended lifespan: In the middle and later stages of battery life, by linearly reducing the upper limit of charging, the chemical stress inside the battery is significantly reduced, thereby slowing down the rate of SOH decay and extending the effective lifespan of the battery. 3. User experience optimization: The innovative SOC recalculation logic avoids sudden changes or inaccuracies in battery display caused by the reduction of the charging limit, allowing users to intuitively perceive the battery status, achieving a smooth transition in battery life, and avoiding the inconvenience caused by sudden power outages; 4. High adaptability: The threshold parameterization design can easily adapt to electric bicycle batteries of different material systems and specifications, and has good versatility and portability. Detailed Implementation

[0018] The present invention will now be further described.

[0019] This embodiment provides a method for controlling the upper limit of electric bicycle battery charging based on two-dimensional aging, including the following steps: S1, Parameter Acquisition and Configuration: Obtain the current battery health status SOH and the usage time Y0, and pre-store a set of configurable threshold parameters in the system, including cycle aging start threshold, cycle aging end threshold, calendar aging start time, and calendar aging end time. S2, the charging upper limit based on the cycle aging dimension is obtained: based on the proportional relationship between the battery health state SOH and the cycle aging start threshold and cycle aging termination threshold, the charging upper limit U_cycle in the cycle aging dimension is obtained; S3. Obtain the charging upper limit based on the calendar aging dimension: According to the proportional relationship between the current used duration and the calendar aging start duration and the calendar aging end duration, obtain the charging upper limit U_time of the calendar aging dimension; S4. Compare and obtain the final charging upper limit; Compare the two upper limit values calculated in S2 and S3, and take the minimum value as the final actually executed charging upper limit U_final = min(U_cycle, U_time). Taking the strictest limit ensures that the control strategy is always dominated by the dimension with more severe aging and more stringent restrictions, maximizing the protection of the battery safety; S5. Charging protection: The BMS controls the charging process based on U_final. When the battery charge reaches the current maximum available capacity × U_final, the charging stops; S6. Forced protection: At any time, if U_final = 0%, that is, when either of the conditions SOH ≤ cycle termination threshold or used duration ≥ calendar end duration is met, the BMS triggers forced protection: cut off the charging MOSFET and prohibit any charging behavior.

[0020] The specific method for obtaining the state of health SOH of the current battery in step S1 is as follows: S11. The BMS collects the voltage, current, and temperature data of the battery in real time; S12. Estimate the current maximum available capacity of the battery based on the collected data; S13. Obtain the state of health SOH = current maximum available capacity / factory rated capacity × 100%. Calculate the used duration by recording or reading the factory time of the battery. Among them, in step S12, a general capacity estimation method in the battery management system is adopted, such as the ampere-hour integration method, open-circuit voltage method, or Kalman filtering method, and comprehensive estimation is carried out by combining multi-dimensional data such as the voltage, current, and temperature of the battery.

[0021] In step S1, the cycle aging start threshold is set to 70% - 80% of SOH, indicating the starting point for the battery to enter the cycle aging decline period; the cycle aging termination threshold is set to 50% - 60% of SOH, indicating the end of the battery cycle life; the calendar aging start duration is set to 5 - 8 years, indicating that the battery begins to be significantly affected by calendar aging; the calendar aging end duration is set to 8 - 10 years, indicating the end of the battery calendar life. In specific practical applications, it can be configured according to different battery types, usage environments, and safety requirements.

[0022] In step S2, when SOH > cycle aging start threshold, U_cycle = 100%, indicating that the battery state of health is good; when cycle aging termination threshold < SOH ≤ cycle aging start threshold, According to the linear interpolation rule, U_cycle decreases linearly from 100% to 0%, indicating that the battery has entered the cycle aging and degradation period; when SOH ≤ cycle aging termination threshold, U_cycle = 0%, at which point the battery cycle life ends.

[0023] In step S3, when the used time is less than the calendar aging start time, U_time = 100%; when the calendar aging start time is less than or equal to the used time but less than the calendar aging end time, According to the linear interpolation rule, U_time decreases linearly from 100% to 0%, indicating that the battery has entered the calendar aging and degradation period; when the used time is greater than or equal to the calendar aging termination time, U_time = 0%, indicating that the battery calendar life has ended.

[0024] In step S5, the BMS simultaneously recalculates and displays the SOC based on the current maximum available capacity as 100%. The SOC display value is calculated as (current remaining battery capacity / current maximum available capacity) × 100%. Through the recalculation of SOC, even if U_final is limited to 50%, the SOC display value will still be 100% when the battery is charged to this limit. The user sees a fully charged state, but the actual battery life will be reduced due to both capacity decay and the charging limit, thus achieving a smooth soft landing.

[0025] In step S6, after the forced protection is triggered, the battery status is reported to the host computer or instrument through a communication interface, such as a CAN interface or a UART interface, prompting the user to replace it; or the battery status is reported through the power indicator light board, prompting the user to replace it, thereby achieving forced and safe retirement of the battery. Example

[0026] This embodiment describes a situation where the battery has a short service life but a high number of cycles.

[0027] In this embodiment, the battery health status (SOH) is 60%, and the usage time (Y0) is 3 years. The specific configured threshold parameters are: cycle start threshold = 70%, cycle termination threshold = 50%; calendar start duration = 7 years, calendar termination duration = 10 years.

[0028] The upper limit of the charging U_cycle trigger interval SOH ∈ [50%, 70%] is based on the cyclic aging dimension, and the linear interpolation is U_cycle = 50%.

[0029] The charging limit U_time is based on the calendar aging dimension. Since the usage time is 3 years < 7 years, U_time = 100%.

[0030] Therefore, the final charging limit U_final = min(50%, 100%) = 50%.

[0031] Therefore, in this embodiment, the final charging limit of the battery is 50%. The BMS controls the battery to only charge to 50% of its current maximum usable capacity before stopping. The SOC display is based on the current capacity, and shows 100% when charging reaches the upper limit. The user feels that the battery is fully charged, but the battery life is significantly shortened, achieving a soft landing caused by cycle aging. Example

[0032] This embodiment is designed for cases where the battery has a long service life and a high number of cycles.

[0033] In this embodiment, the battery health status (SOH) is 65%, and the usage time (Y0) is 8 years. The specific configured threshold parameters are: cycle start threshold = 70%, cycle termination threshold = 50%; calendar start time = 7 years, calendar termination time = 10 years.

[0034] The charging limit U_cycle is based on the cyclic aging dimension: trigger interval: SOH ∈ [50%, 70%], corresponding to the charging limit ∈ [0%, 100%].

[0035] SOH = 65%, the decrease relative to 70% is (70%-65%) / (70%-50%) = 5% / 20% = 25%. Therefore, U_cycle = 1 - 25% = 75%.

[0036] The charging limit U_time is based on the calendar aging dimension: trigger interval: years ∈ [7 years, 10 years], corresponding to the charging limit ∈ [100%, 0%].

[0037] The time frame is 8 years, and the proportion of 7 years elapsed is (8-7) / (10-7) = 1 / 3 ≈ 33.3%. Therefore, U_time = 1-33.3% = 66.7%.

[0038] Therefore, the final charging limit U_final = min(75%, 66.7%) = 66.7%.

[0039] In this embodiment, the final charging limit is determined by a more stringent calendar aging dimension, which is 66.7%. This ensures that even if the battery cycle status is still acceptable, a SOH of 65% still indicates a high level of health. However, since the battery has been aged for 8 years, the charging limit has been proactively lowered to avoid potential safety risks caused by natural material aging. The user actually charges the battery to 66.7% of its current maximum capacity, and the SOC display is still based on the current capacity. A full charge displays 100%, achieving a smooth transition. Example

[0040] This embodiment describes the forced protection of the battery.

[0041] When the battery's cycle life ends, i.e., when the battery's SOH = 49% ≤ cycle termination threshold of 50%, U_cycle = 0%, U_final = 0%, the BMS forcibly disables charging.

[0042] When the battery's calendar life ends, if the battery's usage time is 10.5 years or more and the calendar end time is 10 years, then U_time = 0%, U_final = 0%, and the BMS forcibly disables charging.

[0043] Regardless of whether it's the end of the cycle life or the end of the calendar life, once U_final=0%, the system immediately activates the safety fallback mechanism, cuts off the charging circuit and scraps the battery, eliminating the possibility of safety accidents such as thermal runaway caused by severe battery aging from the root.

[0044] This invention employs a dual-dimensional independent judgment mechanism, treating cycle aging (represented by SOH) and calendar aging (represented by manufacturing time) as two completely independent judgment channels. These channels calculate their respective charging upper limit constraints in parallel, without interference. The minimum constraint value calculated from both dimensions is selected as the final execution standard, ensuring the strictest limit always adheres to the safest and most conservative protection principle for the battery. All key trigger and termination thresholds, such as SOH and age thresholds, are designed as configurable parameters rather than fixed constants. This parameterized threshold design allows for flexible adaptation to batteries with different chemical systems. After the charging upper limit is lowered, the SOC display logic automatically switches the benchmark, always using the "current actual maximum usable capacity" as 100% for linear SOC display recalculation, ensuring the user always sees a complete 0-100% battery level display, intuitive and without abrupt changes. When any aging dimension reaches the preset scrapping condition, a safety fallback mechanism ensures the system forcibly prohibits charging, achieving mandatory safe battery retirement and eliminating potential risks.

Claims

1. A method for controlling the upper limit of electric bicycle battery charging based on dual-dimensional aging, characterized in that: Includes the following steps: S1, Parameter Acquisition and Configuration: Obtain the current battery health status SOH and the usage time Y0, and pre-store a set of configurable threshold parameters in the system, including cycle aging start threshold X1, cycle aging end threshold X2, calendar aging start time Y1, and calendar aging end time Y2. S2, the charging upper limit based on the cycle aging dimension is obtained: based on the proportional relationship between the battery health state SOH and the cycle aging start threshold and cycle aging termination threshold, the charging upper limit U_cycle in the cycle aging dimension is obtained; S3, derive the charging limit based on the calendar aging dimension: based on the ratio of the current used time to the calendar aging start time and calendar aging end time, derive the charging limit U_time of the calendar aging dimension; S4, by comparison, determines the final charging limit; Compare the two upper limit values ​​calculated by S2 and S3, and take the minimum value as the final actual charging upper limit U_final = min(U_cycle, U_time); S5, Charging Protection: The BMS controls the charging process based on U_final. When the battery level reaches the current maximum usable capacity × U_final, charging stops.

2. The method for controlling the upper limit of electric bicycle battery charging based on dual-dimensional aging according to claim 1, characterized in that: The specific method for obtaining the current battery health status (SOH) in step S1 is as follows: S11, the BMS collects the battery's voltage, current, and temperature data in real time; S12, the current maximum usable capacity of the battery is estimated based on the collected data; S13, the battery health status (SOH) is calculated as: current maximum usable capacity / factory rated capacity × 100%.

3. The method for controlling the upper limit of electric bicycle battery charging based on dual-dimensional aging according to claim 1, characterized in that: In step S1, the battery's manufacturing date is recorded or read, and the usage time is calculated.

4. The method for controlling the upper limit of electric bicycle battery charging based on dual-dimensional aging according to claim 1, characterized in that: In step S1, the cycle aging start threshold is set to 70%~80% of SOH; the cycle aging termination threshold is set to 50%~60% of SOH; the calendar aging start duration is set to 5~8 years; and the calendar aging termination duration is set to 8~10 years.

5. The method for controlling the upper limit of electric bicycle battery charging based on dual-dimensional aging according to claim 1, characterized in that: In step S2, when SOH > cycle aging start threshold, U_cycle = 100%; when cycle aging termination threshold < SOH ≤ cycle aging start threshold, When SOH ≤ the cycle aging termination threshold, U_cycle = 0%.

6. The method for controlling the upper limit of electric bicycle battery charging based on dual-dimensional aging according to claim 1, characterized in that: In step S3, when the used time is less than the calendar aging start time, U_time = 100%; when the calendar aging start time is less than or equal to the used time but less than the calendar aging end time, When the used time is greater than or equal to the calendar aging-out time, U_time = 0%.

7. The method for controlling the upper limit of electric bicycle battery charging based on dual-dimensional aging according to claim 1, characterized in that: In step S5, the BMS simultaneously recalculates and displays the SOC based on the current maximum available capacity as 100%. The displayed SOC value is calculated as (current remaining power / current maximum available capacity) × 100%.

8. The method for controlling the upper limit of electric bicycle battery charging based on dual-dimensional aging according to claim 1, characterized in that: It also includes step S6, forced protection: at any time, if U_final = 0%, the BMS triggers forced protection: cuts off the charging MOSFET and prohibits any charging behavior.

9. The method for controlling the upper limit of electric bicycle battery charging based on dual-dimensional aging according to claim 8, characterized in that: In step S6, after the forced protection is triggered, the battery status is reported to the host computer or instrument through the communication interface to prompt the user to replace it; or the battery status is reported through the power indicator light board to prompt the user to replace it.