Battery Life Protection Method

Abstract

The present invention relates to a battery life protection method, and particularly to the battery life protection of an electric vehicle. The battery life protection method includes the following steps: Step 1, comparing the actual total number of cycles N1 with the theoretical total number of cycles Nx that have occurred; or, comparing the actual total throughput C1 with the theoretical total throughput Cx that has occurred; Step 2, if N1 > Nx or C1 > Cx, comparing the actual number of cycles n1 on the current day with the designed number of cycles n per day of the battery, or, comparing the actual capacity throughput c1 on the current day with the theoretical throughput c per day of the battery; if n1 > n or c1 > c, restricting the number of charge-discharge cycles on the current day; if n1 < n or c1 < c, calculating the remaining number of cycles n2 that can be performed per day of the battery or the remaining throughput c2 that can be achieved per day; if n1 > n2 or c1 > c2, restricting the number of charge-discharge cycles of the battery on the current day; if n1 < n2 or c1 < c2, not restricting the charge-discharge of the battery. The above solution can effectively achieve battery life protection and reduce the risk of battery abuse.

Description

Technical Field

[0001] The present invention relates to a method for protecting the battery life, and particularly to the protection of the battery life of electric vehicles. Background Art

[0002] In recent years, the electric vehicle industry has achieved great development. During the industrialization process of electric vehicles, due to limitations such as the level of technological development and infrastructure, the problem that the battery power configuration of electric vehicles does not match the driving range of users is relatively prominent, that is, the problem that the vehicle cannot meet the need of the daily operation driving range after being fully charged at night. Especially for public transportation vehicles, in order to maximize the operation mileage to obtain the maximum economic benefits, users will charge the vehicle power battery multiple times within a single day. Limited by the current technological level of power batteries, multiple repeated charging will cause the battery system to be overheated, leading to safety risks such as overcharging and thermal runaway; at the same time, multiple cyclic charging of the power battery at high temperature within a single day will accelerate the capacity attenuation, resulting in the premature end of the system life and unable to meet the established life design goal. The service life of in-vehicle power batteries is usually evaluated by the capacity attenuation ratio after a certain number of charge and discharge cycles; assuming the rated capacity of the power battery is C, the designed life is N charge and discharge cycles, and the capacity retention rate is M%. Since the service life of the power battery required by users is Y, it is necessary to consider how to reduce the number of battery cycles to meet the requirement of reaching Y years of use.

[0003] In the industry, to solve the problem of the mismatch between the vehicle power configuration and the driving range and avoid the risk of safety accidents caused by battery abuse, currently, mainly a management method of guiding use is adopted, that is, through after-sales service training, customers are forced not to allow multiple charging and the driving range is restricted. However, such restrictions are directly linked to the usage needs and economic interests of customers, often causing dissatisfaction among users, and the results are not ideal. If a liquid-cooled battery solution is adopted to avoid the high temperature of the battery system, in addition to the need to add a water-cooling device structure design to the power battery, it is also necessary to add components such as a water-cooling unit and water-cooling pipes to the whole vehicle, which will increase a lot in terms of structural layout, vehicle weight, and cost. In addition, although the liquid-cooled battery system can alleviate the battery high temperature problem, it cannot fundamentally solve the problem of the service life of the power battery. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for protecting the battery life, so as to solve the problem that it is difficult to effectively protect the battery life in the prior art.

[0005] The following technical solutions are adopted in the present invention:

[0006] A method for protecting the battery life, comprising the following steps:

[0007] Step 1: Compare the actual total number of cycles N1 dynamically calculated by the battery management system with the theoretical total number of cycles Nx; or, compare the actual total throughput C1 dynamically calculated by the battery management system with the theoretical total throughput Cx;

[0008] Nx = the number of designed cycles per day n * the actual number of days of use Tx;

[0009] n = the designed number of cycles N of the battery / the designed life days T;

[0010] Cx = Nx * the rated capacity C of the battery;

[0011] Step 2: If N1 > Nx or C1 > Cx, compare the actual number of cycles n1 on the current day dynamically calculated by the battery management system with the number of designed cycles per day n of the battery, or, compare the actual capacity throughput c1 on the current day dynamically calculated by the battery management system with the theoretical throughput per day c of the battery;

[0012] c = n * the rated capacity C of the battery;

[0013] n1 = c1 / C;

[0014] If n1 > n or c1 > c, limit the subsequent discharge current on the current day and / or do not allow the battery to be charged on the current day and / or do not allow the battery to be discharged after charging on the current day;

[0015] If n1 < n or c1 < c, calculate the remaining number of cycles per day n2 or the remaining throughput per day c2 of the battery;

[0016] n2 = (the designed number of cycles N - the actual total number of cycles N1) / (the designed life days T - the actual number of days of use Tx);

[0017] c2 = the remaining theoretical total throughput C2 / (the designed life days T - the actual number of days of use Tx);

[0018] If n1 > n2 or c1 > c2, limit the subsequent discharge current on the current day and / or do not allow the battery to be charged on the current day and / or do not allow the battery to be discharged after charging on the current day;

[0019] If n1 < n2 or c1 < c2, do not limit the charge and discharge of the battery.

[0020] Beneficial effects: By adopting the above technical solution, it is possible to determine whether the current battery is used in advance by comparing N1 with Nx or C1 with Cx. In the case of advance use, it is possible to judge the daily usage situation by comparing n1 with n or c1 with c and impose restrictions in a timely manner. When the actual daily usage does not exceed the standard, the daily battery usage is controlled with the goal of meeting the overall service life by comparing n1 with n2 or c1 with c2, thereby realizing the control of battery usage from the vehicle's own functions, preventing the driver from using it arbitrarily according to their own will, effectively protecting the battery life, meeting the service life requirements, and reducing the risk of safety accidents caused by battery abuse.

[0021] As a preferred technical solution: When used again on the same day, the subsequent discharge current on the same day is restricted starting from that time.

[0022] Beneficial effects: By adopting the above technical solution, it is possible to avoid a decrease in power during normal vehicle driving, which may affect safe driving.

[0023] As a preferred technical solution: The subsequent discharge current on the same day is restricted to 50A.

[0024] Beneficial effects: By adopting the above technical solution, it is possible to provide a limp-home function and better avoid an increase in capacity throughput.

[0025] As a preferred technical solution: When restricting the subsequent discharge current on the same day and / or not allowing the battery to be charged on the same day and / or not allowing the battery to be discharged after charging on the same day, it is also not allowed to perform regenerative braking energy recovery on the battery.

[0026] Beneficial effects: Not allowing regenerative braking energy recovery on the battery can better control capacity throughput.

[0027] As a preferred technical solution: If N1 > Nx or C1 > Cx on the same day, then, on the next day, calculate the remaining daily cycle times n2 or the remaining daily throughput c2 of the battery, and compare n1 with n2 or c1 with c2. According to the comparison result, adopt the same control method as the previous day until N1 ≤ Nx or C1 ≤ Cx.

[0028] Beneficial effects: By adopting the above technical solution, it is possible to continuously control the use of the battery, which is more conducive to achieving the overall service life goal.

[0029] As a preferred technical solution: In step two, first judge whether n1 > n or c1 > c, and N1 > Nx or C1 > Cx holds. If it does not hold, then judge whether n1 < n or c1 < c, and N1 > Nx or C1 > Cx holds.

[0030] Beneficial effects: The above technical solution can reduce the judgment process and improve the response speed.

[0031] As a preferred technical solution: In step two, if n1 > n or c1 > c does not hold and N1 > Nx or C1 > Cx does not hold, or n1 < n or c1 < c does not hold and N1 > Nx or C1 > Cx also does not hold, then the charge and discharge of the battery are not restricted.

[0032] Beneficial effects: The above technical solution can give full play to the vehicle performance while meeting the overall service life and avoiding battery abuse.

[0033] As a preferred technical solution: When n1 = n or c1 = c, the same control method as when n1 < n or c1 < c is adopted.

[0034] As a preferred technical solution: When n1 = n2 or c1 = c2, the same control method as when n1 < n2 or c1 < c2 is adopted.

[0035] As a preferred technical solution: The designed life and actual service life of the battery are in years. The designed number of charge and discharge cycles per day n = designed life of the battery / 365, and the actual number of days of use Tx = actual service life / 365. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is the overall control flow block diagram of the battery life protection method in the present invention;

[0037] Figure 2 is the control flow block diagram of the first case in Embodiment 1 of the battery life protection method in the present invention;

[0038] Figure 3 is the control flow block diagram of the second case in Embodiment 1 of the battery life protection method in the present invention;

[0039] Figure 4 is the control flow block diagram of the third case in Embodiment 1 of the battery life protection method in the present invention;

[0040] Figure 5 is the control flow block diagram of the fourth case in Embodiment 1 of the battery life protection method in the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0041] In order to make the objectives, technical solutions and advantages of the present invention more clear and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Usually, the components of the embodiments of the present invention described and illustrated herein can be arranged and designed in various different configurations.

[0042] Therefore, the detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0043] It should be noted that relational terms such as "first" and "second" that may appear in the specific embodiments of the present invention are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "including", "comprising" or any other variant thereof that may appear are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, the elements defined by the statement "including one..." do not exclude the existence of additional identical elements in the process, method, article or device including the said elements.

[0044] In the description of the present invention, unless otherwise clearly defined and limited, the terms "installed", "connected" and "coupled" that may appear should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be a direct connection or an indirect connection through an intermediate medium, and it may be the communication inside two elements. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood through specific circumstances.

[0045] In the description of the present invention, unless otherwise clearly defined and limited, the term "provided with" that may appear should be understood in a broad sense. For example, the object of "provided with" may be a part of the body, or may be arranged separately from the body and connected to the body, and this connection may be a detachable connection or a non-detachable connection. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood through specific circumstances.

[0046] Taking the battery life protection of electric vehicles as an example, the battery life protection method in the present invention can manage the service life of power batteries and reduce the risk of safety accidents caused by battery abuse.

[0047] For example Figure 1 , to achieve the capacity retention rate target and protect the battery life, first calculate the designed daily cycle times n = N / Y / 365 (times) of the power battery. Based on the designed daily cycle times n, calculate the theoretical daily throughput c of the power battery = the rated capacity C of the battery * n. According to the standard cycle times and the theoretical daily throughput of the power battery, the capacity attenuation of the power battery can be ensured not to be less than M% during the service life of Y years. Among them, n = the designed cycle times N of the battery / the designed life days T.

[0048] Then, based on this, calculate and control the use of the power battery. If the vehicle has actually operated for Y1 years, the total theoretical cycle times Nx of the current power battery = n * Y1 * 365. The battery management system (BMS) of the vehicle dynamically calculates the actual capacity throughput c1 of the day and the actual cycle times n1 = c1 / C of the day, and the battery management system dynamically calculates the total actual cycle times N1 of the power battery. Of course, the dynamic calculation can be real-time calculation or calculation at intervals according to set rules on the same day.

[0049] Through the control system, different control methods are adopted in the following four cases respectively to protect the battery life:

[0050] The first case:

[0051] If the actual cycle times n1 of the power battery on the same day > the designed daily cycle times n, and the total actual cycle times N1 of the power battery > the total theoretical cycle times Nx, when both conditions are met, the capacity throughput of the power battery is restricted, and the charge and discharge cycle times of the vehicle's power battery on the same day are restricted.

[0052] The specific way to restrict the capacity throughput: when the vehicle is used again on the same day, the battery management system restricts the allowable discharge current to 50A to allow the vehicle to limp back to the factory; in addition, the battery is not allowed to be charged on the same day to avoid the vehicle being used again on the same day after charging, and it is also not allowed to charge the battery in the form of regenerative braking energy recovery. In this way, the vehicle can be restricted from continuing to be used on the same day as a whole.

[0053] On the second day, calculate the remaining number of daily charge-discharge cycles \(n_2\) or the remaining daily throughput \(c_2\) of the battery; \(n_2=(N - N_1) / (T - T_x)\), that is, \(n_2 = N_2 / Y_2 / 365\) (times), where \(Y_2 = Y - Y_1\); \(c_2=\text{remaining theoretical total throughput}C_2 / (T - T_x)\), and \(C_2 = n_2\times C\).

[0054] If \(n_1>n_2\) or \(c_1>c_2\), restrict the throughput of the power battery capacity again until \(N_1\leq N_x\) or \(C_1\leq C_x\), and the power battery can be used normally again.

[0055] The second case:

[0056] If the actual number of charge-discharge cycles \(n_1\) of the power battery on the current day is greater than the designed number of daily charge-discharge cycles \(n\), and the actual total number of charge-discharge cycles \(N_1\) of the power battery is less than the theoretically cycled total number \(N_x\), then the charge and discharge of the battery are not restricted, and the charge-discharge cycle times of the vehicle's power battery on the current day are not restricted.

[0057] The third case:

[0058] If the actual number of charge-discharge cycles \(n_1\) of the power battery on the current day is less than the designed number of daily charge-discharge cycles \(n\), and the actual total number of charge-discharge cycles \(N_1\) of the power battery is greater than the theoretically cycled total number \(N_x\), when both conditions are met, calculate the remaining number of daily charge-discharge cycles \(n_2\) or the remaining daily throughput \(c_2\) of the battery;

[0059] \(n_2=(N - N_1) / (T - T_x)\), that is, \(n_2=\text{theoretically remaining total number of cycles}N_2 / Y_2 / 365\) (times), where \(Y_2 = Y - Y_1\); \(c_2=\text{remaining theoretical total throughput}C_2 / (T - T_x)\), and \(C_2 = n_2\times C\).

[0060] If \(n_1>n_2\) or \(c_1>c_2\), restrict the throughput of the power battery capacity until \(N_1\leq N_x\) or \(C_1\leq C_x\).

[0061] If \(n_1<n_2\) or \(c_1<c_2\), do not restrict the charge and discharge of the battery. At the same time, the battery management system accumulatively calculates the actual total number of charge-discharge cycles \(N_1\).

[0062] On the second day, calculate the remaining number of daily charge-discharge cycles \(n_2\) or the remaining daily throughput \(c_2\) of the battery again, and compare \(n_1\) with \(n_2\) or \(c_1\) with \(c_2\). According to the comparison results, adopt the same control method as the previous day until \(N_1\leq N_x\) or \(C_1\leq C_x\), and the power battery can be used normally again.

[0063] The fourth case:

[0064] If the actual number of cycles n1 of the power battery on the current day < the designed number of cycles per day n, and the actual total number of cycles N1 of the power battery < the theoretical total number of cycles Nx that should have been completed, then there is no restriction on the charge and discharge of the battery, and there is no restriction on the number of charge and discharge cycles of the vehicle's power battery on the current day.

[0065] The above solution adopts fuzzy logic, uses fuzzy rules for reasoning, calculates the remaining number of cycles n2 that the battery can complete per day, controls the battery capacity throughput, and then restricts the number of charge and discharge cycles, thereby realizing the effective management of the service life of the power battery and avoiding potential safety hazards such as high temperature and high pressure caused by battery abuse.

[0066] The following further describes the present invention in detail with reference to specific embodiments.

[0067] Embodiment 1 of the battery life protection method in the present invention:

[0068] The rated capacity of the in-vehicle power battery is 400 AH. After 4500 standard charge and discharge cycles at room temperature, the capacity retention rate is 80% * 400 AH = 320 AH. The user requires the service life of the in-vehicle power battery, that is, the designed life, to be 8 years. That is, after 8 years of use, the capacity retention rate of the power battery is not less than 80% (320 AH). It is possible to ensure that the capacity retention rate of the battery system is not less than 80% after capacity attenuation within 8 years, that is, the purpose of battery life protection is achieved.

[0069] First, according to the designed number of cycles and designed service life of the battery, calculate the designed number of cycles per day n of the in-vehicle power battery system = 4500 (cycles) / 8 (years) / 365 = 1.54 cycles; then, based on the designed number of cycles per day n, calculate the theoretical daily throughput c of the power battery system = 400 (AH) * 1.54 (cycles) = 616 AH.

[0070] For example Figure 2 , if the actual operation time of the vehicle Y1 = 3 years, the battery management system records the actual total number of cycles N1 of the in-vehicle power battery = 1800 times, and the actual number of cycles n1 of the power battery dynamically recorded by the battery management system in the current state on the current day = 1.64 times, and the actual capacity throughput c1 on the current day = 400 (AH) * 1.64 (cycles) = 656 AH; the theoretical total number of cycles Nx that should have been completed for the power battery after 3 years of vehicle operation Y1 = 3 years * 365 (days) * 1.54 (cycles) = 1686 times.

[0071] Because the actual total number of cycles N1 (1800 times) of the in-vehicle power battery after 3 years of operation > the theoretical total number of cycles Nx (1686 times) that should have been completed for the power battery after 3 years of vehicle operation, and the actual number of cycles n1 (1.64 times) of the current power battery on the current day > the designed number of cycles per day n (1.54 times), at this time, it is necessary to restrict the charge and discharge throughput of the power battery per day, and then restrict the number of charge and discharge cycles per day.

[0072] Specific limitation method for capacity throughput: When the vehicle is used again on the same day, the battery management system limits the subsequent discharge current on the same day to 50 A. Charging the battery is not allowed on the same day, nor is it allowed to charge the battery by regenerative braking energy recovery.

[0073] On the next day, calculate the remaining daily cycle times n2 of the battery. First, calculate the theoretical remaining total cycle times N2 = N - N1 = 4500 (times) - 1800 (times) = 2700 (times). Calculate the theoretical remaining operating time Y2 = Y - Y1 = 8 (years) - 3 (years) = 5 years. Then, for the remaining life of the power battery, the remaining daily cycle times n2 on the same day = N2 / Y2 / 365 (times) = 2700 (times) / 5 (years) / 365 (times) = 1.48 times. Calculate the remaining daily throughput c2 = n2 * C = 1.48 * 400 = 592 AH. If the actual capacity throughput c1 on the same day > the remaining daily throughput c2 = 592 AH, limit the capacity throughput of the power battery again until N1 ≤ Nx, and the power battery resumes normal use.

[0074] However, for example, if Figure 4 , when the actual cycle times n1 of the power battery on the same day = 1.64 times > the designed daily cycle times n = 1.54 times, and the actual total cycle times N1 of the power battery < the theoretical total cycle times Nx = 1686 times, then the charging and discharging of the battery are not restricted, and the charging and discharging cycle times of the vehicle's power battery on the same day are not restricted.

[0075] However, for example, if Figure 5 , when the actual cycle times n1 of the power battery on the same day = 1.5 times < the designed daily cycle times n = 1.54 times, and the actual total cycle times N1 of the power battery < the theoretical total cycle times Nx = 1686 times, then the charging and discharging of the battery are not restricted, and the charging and discharging cycle times of the vehicle's power battery on the same day are not restricted.

[0076] However, for example, if Figure 3 , when the actual cycle times n1 of the power battery on the same day = 1.5 times < the designed daily cycle times n = 1.54 times, and the actual total cycle times N1 of the power battery = 1800 times > the theoretical total cycle times Nx = 1686 times, then calculate the theoretical remaining total cycle times N2 = N - N1 = 4500 (times) - 1800 (times) = 2700 (times). Calculate the theoretical remaining operating time Y2 = Y - Y1 = 8 (years) - 3 (years) = 5 years. Then, for the remaining life of the power battery, the remaining daily cycle times n2 on the same day = N2 / Y2 / 365 (times) = 2700 (times) / 5 (years) / 365 (times) = 1.48 times. Calculate the remaining daily throughput c2 = n2 * C = 1.48 * 400 = 592 AH.

[0077] If the actual capacity throughput c1 on the same day < the remaining daily throughput c2 = 592 AH, there is no restriction on the charge and discharge of the battery, and there is no restriction on the number of charge and discharge cycles of the vehicle's power battery on the same day.

[0078] As the vehicle is used on the same day, if the actual capacity throughput c1 on the same day > the remaining daily throughput c2 = 592 AH, then the capacity throughput of the power battery is restricted, and further the number of charge and discharge cycles per day is restricted.

[0079] Specific method for restricting capacity throughput: When the vehicle is used again on the same day, the battery management system restricts the subsequent discharge current on the same day to 50 A, and it is not allowed to charge the battery on the same day, nor is it allowed to charge the battery by means of regenerative braking energy recovery.

[0080] On the next day, calculate the remaining daily cycle times n2 of the battery again. The remaining daily throughput c2 = n2 * C. If the actual capacity throughput c1 on that day > the remaining daily throughput c2 = 592 AH, restrict the capacity throughput of the power battery again until N1 ≤ Nx, and the power battery resumes normal use.

[0081] Example 2 of the battery life protection method in the present invention:

[0082] The difference between this embodiment and Embodiment 1 is that in Embodiment 1, the usage situation of the battery is judged by comparing the actual total cycle times N1 dynamically calculated by the battery management system with the theoretically completed cycle times Nx, while in this embodiment, the usage situation of the battery is judged by comparing the actual total throughput C1 dynamically calculated by the battery management system with the theoretically completed throughput Cx, and Cx = Nx * the rated capacity C of the battery.

[0083] Example 3 of the battery life protection method in the present invention:

[0084] The difference between this embodiment and Embodiment 1 is that in Embodiment 1, the usage situation of the battery on the same day is judged by comparing the actual cycle times n1 on the same day dynamically calculated by the battery management system with the designed daily cycle times n of the battery, while in this embodiment, the usage situation of the battery on the same day is judged by comparing the actual capacity throughput c1 on the same day dynamically calculated by the battery management system with the theoretically daily throughput c of the battery, and c = n * the rated capacity C of the battery.

[0085] Example 4 of the battery life protection method in the present invention:

[0086] The difference between this embodiment and Embodiment 1 is that in Embodiment 1, when the vehicle is used again on the same day, the subsequent discharge current on the same day starts to be restricted, which is beneficial to improving safety. In this embodiment, after meeting the corresponding conditions, an alarm prompt is given, and after a delay of the set time, the subsequent discharge current on the same day starts to be restricted.

[0087] Embodiment 5 of the battery life protection method in the present invention:

[0088] The difference between this embodiment and Embodiment 1 is that in Embodiment 1, restricting the charge and discharge cycle times of the vehicle's power battery on the same day is achieved by restricting the subsequent discharge current on the same day and not allowing the battery to be charged on the same day. In this embodiment, the battery is allowed to be charged on the same day, however, it is not allowed to discharge after charging on the same day, and it is only allowed to discharge on the next day.

[0089] Embodiment 6 of the battery life protection method in the present invention:

[0090] The difference between this embodiment and Embodiment 1 is that in Embodiment 1, it is first judged whether n1 > n and N1 > Nx hold. If not, it is then judged whether n1 < n and N1 < Nx hold. In this embodiment, it is first judged whether n1 < n and N1 < Nx hold, and then successively judged whether n1 > n and N1 < Nx hold, whether n1 > n and N1 > Nx hold, and whether n1 < n and N1 < Nx hold. Of course, in other embodiments, the judgment can also be made in other orders.

[0091] The above is only the preferred embodiment of the present invention, and it is not intended to limit the present invention. The patent protection scope of the present invention is subject to the claims. All equivalent structural changes made by using the description and drawings of the present invention should equally be included in the protection scope of the present invention.

Claims

1. Battery life protection method, characterized in that, It includes the following steps: Step 1: Compare the actual total number of cycles N1 dynamically calculated by the battery management system with the theoretical total number of cycles Nx that have occurred; alternatively, compare the actual total throughput C1 dynamically calculated by the battery management system with the theoretical total throughput Cx that has occurred; Nx = the number of designed cycles per day n * the actual number of days of use Tx; n = the designed number of cycles N of the battery / the designed life days T; Cx = Nx * the rated capacity C of the battery; Step 2: If N1 > Nx or C1 > Cx, compare the actual number of cycles n1 on the current day dynamically calculated by the battery management system with the number of designed cycles per day n of the battery; alternatively, compare the actual capacity throughput c1 on the current day dynamically calculated by the battery management system with the theoretical daily throughput c of the battery; c = n * the rated capacity C of the battery; n1 = c1 / C; If n1 > n or c1 > c, limit the subsequent discharge current on the current day and / or do not allow the battery to be charged on the current day and / or do not allow the battery to be discharged after charging on the current day; If n1 < n or c1 < c, calculate the remaining number of cycles per day n2 or the remaining daily throughput c2 of the battery; n2 = (the designed number of cycles N - the actual total number of cycles N1) / (the designed life days T - the actual number of days of use Tx); c2 = the remaining theoretical total throughput C2 / (the designed life days T - the actual number of days of use Tx); If n1 > n2 or c1 > c2, limit the subsequent discharge current on the current day and / or do not allow the battery to be charged on the current day and / or do not allow the battery to be discharged after charging on the current day; If n1 < n2 or c1 < c2, do not limit the charge and discharge of the battery.

2. The battery life protection method according to claim 1, wherein When used again on the current day, start limiting the subsequent discharge current on the current day.

3. The battery life protection method according to claim 1 or 2, characterized in that, The subsequent discharge current on the current day is limited to 50A.

4. The battery life protection method according to claim 1 or 2, characterized in that When limiting the subsequent discharge current on the current day and / or not allowing the battery to be charged on the current day and / or not allowing the battery to be discharged after charging on the current day, it is also not allowed to perform braking energy recovery on the battery.

5. The battery life protection method according to claim 1 or 2, characterized in that, If N1 > Nx or C1 > Cx on the current day, then, on the next day, calculate the remaining number of cycles per day n2 or the remaining daily throughput c2 of the battery, and compare n1 with n2 or c1 with c2. According to the comparison result, adopt the same control method as the previous day until N1 ≤ Nx or C1 ≤ Cx.

6. The battery life protection method according to claim 1 or 2, characterized in that, In Step 2, first determine whether n1 > n or c1 > c, and N1 > Nx or C1 > Cx holds. If it does not hold, then determine whether n1 < n or c1 < c, and N1 > Nx or C1 > Cx holds.

7. The battery life protection method according to claim 6, wherein In Step 2, if n1 > n or c1 > c does not hold and N1 > Nx or C1 > Cx does not hold, or n1 < n or c1 < c does not hold and N1 > Nx or C1 > Cx also does not hold, then do not limit the charge and discharge of the battery.

8. The battery life protection method according to claim 1 or 2, characterized in that When n1 = n or c1 = c, adopt the same control method as when n1 < n or c1 < c.

9. The battery life protection method according to claim 1 or 2, characterized in that When n1 = n2 or c1 = c2, adopt the same control method as when n1 < n2 or c1 < c2.

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