Battery health monitoring method and electric vehicle trunk

Abstract

The application discloses a battery health monitoring method and a trunk of an electric vehicle, and relates to the technical field of battery health monitoring. Vmax The method comprises the following steps: collecting battery monomer voltage data at every predetermined sampling time, and calculating the average value, the maximum value and the minimum value of the monomer voltage at each sampling time; calculating the monomer voltage dispersion at each sampling time based on the voltage data and the average value; for each sampling time, when the difference between the SOC corresponding to the maximum value of the monomer voltage and the SOC corresponding to the minimum value of the monomer voltage is not less than a predetermined value, the minimum value of the monomer voltage dispersion corresponding to the sampling time is inversely deduced by using the maximum value of the monomer voltage and the minimum value of the monomer voltage; comparing the monomer voltage dispersion at each sampling time with the minimum value of the monomer voltage dispersion corresponding to the sampling time, and determining the SOH of the lithium battery pack at this time. Vmin The battery monitoring module with the above method is arranged in the trunk, and early warning of the battery health state is made.

Description

Technical Field

[0001] This invention relates to the field of battery health monitoring technology, and in particular to a battery health monitoring method and an electric vehicle trunk. Background Technology

[0002] Electric vehicles, as a green and environmentally friendly mode of transportation, have become the preferred mode of travel for many. Lithium batteries, with their advantages of high energy density, light weight, long cycle life, and ease of disassembly, are gradually replacing traditional lead-acid batteries. However, the safety of lithium batteries remains a major concern, as fires can cause personal injury and property damage.

[0003] Traditional electric vehicle rear boxes are only used for storage tools such as helmets, raincoats, and chargers, and are mostly fixed to the rear of the vehicle with screws, making disassembly difficult. This application breaks with traditional thinking and proposes a rear box with charging and battery health monitoring functions. Summary of the Invention

[0004] To address the aforementioned problems and technical requirements, the inventors have proposed a battery health monitoring method and an electric vehicle trunk, which solves the problem of inaccurate battery health prediction. By combining the trunk with the charging module, the battery can be charged without disassembling it, thus solving the safety issues of lithium battery charging.

[0005] The technical solution of the present invention is as follows:

[0006] In a first aspect, this application provides a method for monitoring battery health, comprising the following steps:

[0007] Battery cell voltage data are collected at predetermined sampling times, and the average, maximum and minimum cell voltage values ​​at each sampling time are calculated.

[0008] The dispersion of individual cell voltage at each sampling time is calculated based on the individual cell voltage data and the average value of individual cell voltage.

[0009] For each sampling time, the SOC corresponding to the maximum value of the single-cell voltage Vmax SOC corresponding to the minimum single-cell voltage Vmin When the difference is not less than the predetermined value, the minimum value of the individual voltage dispersion at that sampling time is deduced by using the maximum and minimum values ​​of the individual voltage.

[0010] By comparing the individual cell voltage dispersion at each sampling time with the minimum individual cell voltage dispersion at that sampling time, the SOH of the lithium battery pack at that time is determined.

[0011] A further technical solution involves calculating the individual cell voltage dispersion at each sampling time based on the individual cell voltage data and the average individual cell voltage, expressed as:

[0012]

[0013] Among them, V m,ti This represents the cell voltage data of the m-th cell in the lithium battery pack at sampling time ti;

[0014] This represents the average unit voltage at sampling time ti, and

[0015] A further technical solution involves using the maximum and minimum values ​​of the individual cell voltage to deduce the minimum dispersion of the individual cell voltage at the sampling time, including:

[0016] The individual cell voltage dispersion at sampling time ti is also expressed as:

[0017]

[0018] Where m is the number of battery strings in the lithium battery pack. These represent the maximum and minimum values ​​of the single-cell voltage at sampling time i, respectively.

[0019] This represents the average unit voltage at sampling time ti, and V m,ti This represents the cell voltage data of the m-th cell in the lithium battery pack at sampling time ti; This indicates the removal at sampling time ti. The average value of the remaining individual cell voltages;

[0020] If and only if At that time, σ ti It has a minimum value, expressed as:

[0021]

[0022] A further technical solution involves comparing the individual cell voltage dispersion at each sampling time with the minimum individual cell voltage dispersion at that sampling time to determine the state of equilibrium (SOH) of the lithium battery pack at that time, including:

[0023] If the voltage dispersion of a single cell at each sampling time is not less than the minimum voltage dispersion of the single cell at that sampling time, then the SOH of the lithium battery pack is considered abnormal at that time; otherwise, the SOH of the lithium battery pack is considered normal.

[0024] A further technical solution is that the method also includes:

[0025] By consulting the SOC-OCV table of individual cells in the lithium battery pack, the SOC corresponding to the maximum voltage of the individual cell can be obtained.Vmax and the SOC corresponding to the minimum unit voltage Vmin .

[0026] Secondly, this application also provides an electric vehicle trunk, including an upper cover and a lower cover forming the trunk housing, and a lithium battery pack, a battery monitoring module, a charging module, and a retractable AC plug placed inside the trunk housing; the battery monitoring module is connected to the lithium battery pack and is used to determine the SOH of the lithium battery pack based on the battery health monitoring method of any one of claims 1-5; one end of the charging module is connected to the AC harness of the retractable AC plug, and the other end is connected to the lithium battery pack, and is used to convert AC power into DC power to charge the battery.

[0027] The further technical solution is that the battery monitoring module includes a controller and connected voltage acquisition circuit, current acquisition circuit and alarm circuit; after the vehicle is stationary, when the current acquisition circuit detects that the lithium battery pack current is zero, the voltage acquisition circuit collects the individual battery cell voltage data at predetermined sampling times, and the controller calculates the individual cell voltage dispersion at each sampling time based on the collected individual battery cell voltage data, thereby determining the SOH of the lithium battery pack; the alarm circuit is used to issue a warning when the SOH of the lithium battery pack is abnormal.

[0028] A further technical solution is that the lower cover is also provided with a concave cavity, in which the AC plug is accommodated, and the AC wire harness is orderly coiled inside the lower cover housing below the lithium battery pack.

[0029] The further technical solution is that the upper cover and the lower cover are connected by a hinge, and a handle is installed on the top of the upper cover; the upper cover and the lower cover are made of steel structure, and the inner surface is covered with insulating material.

[0030] A further technical solution is that the battery monitoring module also includes a temperature acquisition circuit connected to the controller. The controller controls the connection and disconnection of the lithium battery pack and the charging module based on the acquired battery temperature, thereby controlling the charging and discharging of the entire vehicle. The alarm circuit is used to issue a warning when the lithium battery pack temperature is abnormal.

[0031] The beneficial technical effects of this invention are:

[0032] Compared to traditional lithium batteries installed in the footrests or seat compartments, which are low and prone to water damage, this application adopts a novel method of installing lithium batteries in the trunk. The footrests or seat compartments serve as storage for miscellaneous items, while the trunk, located at a higher level within the vehicle, significantly reduces the risk of water ingress and short circuits after the battery has been submerged. A battery monitoring module in the trunk provides high-precision current, voltage, and temperature sampling, measuring battery discharge current, charging current, battery voltage, and internal temperature. Based on the battery health monitoring method proposed in this application, it provides early warnings about the battery's health status. A charging module and retractable AC plug in the trunk allow for direct charging, avoiding frequent battery removal. Furthermore, the trunk material is flame-retardant and explosion-proof, isolating the fire source from the vehicle in the event of a fire, minimizing property damage and preventing personal injury. Attached Figure Description

[0033] Figure 1 This is a flowchart of the method provided in Embodiment 1 of this application.

[0034] Figure 2 This is a comparison chart of abnormal voltage dispersion and normal voltage dispersion provided in Embodiment 1 of this application.

[0035] Figure 3 This is a side view of the electric vehicle trunk provided in Embodiment 2 of this application.

[0036] Figure 4 This is a top view of the electric vehicle trunk provided in Embodiment 2 of this application.

[0037] Figure 5 This is a schematic diagram of module connections provided in Embodiment 2 of this application.

[0038] Figure 6 This is a flowchart of the battery monitoring module provided in Embodiment 2 of this application. Detailed Implementation

[0039] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0040] Example 1:

[0041] like Figure 1 As shown, this embodiment provides a battery health monitoring method, including the following steps:

[0042] Step 1: Collect individual cell voltage data every t = 30 minutes, and calculate the average cell voltage at each sampling time. Maximum voltage of a single unit and minimum unit voltage

[0043] Step 2: Calculate the individual cell voltage dispersion at each sampling time based on the individual cell voltage data and the average individual cell voltage. The expression is:

[0044]

[0045] Among them, V m,ti This represents the cell voltage data of the m-th cell in the lithium battery pack at sampling time ti. The array of cell voltages recorded at each sampling time is as follows:

[0046]

[0047] This represents the average unit voltage at sampling time ti, and The average value and voltage dispersion of each individual cell at each sampling time are as follows:

[0048]

[0049] Step 3: For each sampling time, when the SOC corresponds to the maximum value of the single-cell voltage Vmax SOC corresponding to the minimum single-cell voltage Vmin When the difference is not less than a predetermined value, the minimum value of the individual voltage dispersion at that sampling time is derived by using the maximum and minimum values ​​of the individual voltage, including:

[0050] Step 31: According to the SOC-OCV table of the individual cells in the lithium battery pack provided by the manufacturer, Find the corresponding SOC by looking up the table. Vmax ,Will Find the corresponding SOC by looking up the table. Vmin In this embodiment, if SOC Vmax -SOC Vmin If the percentage is ≥10%, the battery health status (SOH) is considered to be unacceptable.

[0051] Step 32: The individual cell voltage dispersion at sampling time ti is also expressed as:

[0052]

[0053] Where m is the number of battery strings in the lithium battery pack. These represent the maximum and minimum individual voltage values ​​at sampling time ti, respectively. This indicates the removal at sampling time ti. The average value of the remaining individual cell voltages.

[0054] If and only if At that time, σ ti It has a minimum value, expressed as:

[0055]

[0056] Step 4: Compare the individual cell voltage dispersion at each sampling time with the minimum individual cell voltage dispersion at that sampling time to determine the SOH of the lithium battery pack at that time, including:

[0057] If the individual unit voltage dispersion at each sampling time is not less than the minimum individual unit voltage dispersion value corresponding to that sampling time, that is... If the SOH of the lithium battery pack is abnormal, it is considered that the SOH of the lithium battery pack is abnormal; otherwise, it is considered that the SOH of the lithium battery pack is normal.

[0058] This embodiment provides the average cell voltage and corresponding OCV values ​​of the lithium battery pack sampled at 24℃ every t = 30 minutes, as well as the calculated values. The correspondence is shown in the table below, according to Different results can be obtained from falling into the interval. If the value is obtained, then σ can be calculated. ti Then, the SOH of the lithium battery pack at each sampling time can be determined by checking the table. By simulating a set of abnormal battery voltage data and normal battery voltage data, curves a showing the variation of abnormal cell voltage dispersion over time and curve b showing the variation of normal cell voltage dispersion over time are obtained respectively, as shown in the figure. Figure 2 As shown, when At that time, a signal indicating an abnormal SOH (State of Health) of the lithium battery pack is given.

[0059]

[0060] Example 2:

[0061] Combination Figure 3 , Figure 4 As shown, this embodiment provides an electric vehicle trunk, including an upper cover 1 and a lower cover 2 forming the trunk housing, and a lithium battery pack 8, a battery monitoring module 3, a charging module 4, and a retractable AC plug 5 placed inside the trunk housing (i.e., the lower cover 2). The upper cover 1 and lower cover 2 are connected by a hinge 9, and a handle 7 is installed on the top of the upper cover 1. The lower cover 2 also has a recessed cavity 10, in which the AC plug 5 is accommodated, and the AC wiring harness 6 is orderly coiled inside the lower cover housing below the lithium battery pack 8. Optionally, the battery monitoring module 3 is installed in front of the lithium battery pack 8 inside the lower cover 2, and the charging module 4 is installed below the battery monitoring module 3. The upper cover 1 and lower cover 2 are made of steel, and their inner surfaces are covered with insulating material, providing external heat insulation and flame-retardant and explosion-proof functions.

[0062] like Figure 5As shown, the battery monitoring module 3 is connected to the lithium battery pack 8 and is used to determine the state of health (SOH) of the lithium battery pack 8 based on the battery health monitoring method provided in Embodiment 1. One end of the charging module 4 is connected to the AC harness 6 of the retractable AC plug 5, and the other end is connected to the lithium battery pack 8. It is used to convert AC power into DC power to charge the battery. That is, when the battery needs charging, the retractable AC plug 5 is pulled out from the trunk cover 2 and connected to an external charging device, at which time the AC harness 6 is rotated out.

[0063] The battery monitoring module 3 includes a controller and connected voltage acquisition circuits, current acquisition circuits, temperature acquisition circuits, and alarm circuits. The module's workflow is as follows: Figure 6 As shown, after the vehicle is stationary, when the current acquisition circuit detects that the lithium battery pack current is zero, the voltage acquisition circuit collects the individual battery cell voltage data V at predetermined sampling times (e.g., t = 30 min). m,ti The controller is based on the collected battery cell voltage data V m,ti Calculate the individual unit voltage dispersion σ at each sampling time. ti This allows for the determination of the SOH (State of Health) of the lithium battery pack. The specific implementation method is described in the battery health monitoring method provided in Example 1, and will not be repeated here.

[0064] In this embodiment, the temperature acquisition circuit can use NTC temperature measurement, which is arranged on each surface of the lithium battery pack 8 to achieve at least six-channel NTC all-round temperature acquisition of the lithium battery pack 8. The controller also controls the on / off switching between the lithium battery pack 8 and the charging module 4 based on the average battery temperature T, thereby controlling the charging and discharging of the entire vehicle. For example, when the temperature T is within the following range (which can be adjusted according to the actual battery parameters), the battery monitoring module 3 and the charging module 4 perform the following actions:

[0065]

[0066] The alarm circuit is used to provide warnings when the lithium battery pack's SOH and temperature are abnormal. This application does not limit the warning method; for example, it can use audible and visual alarms, prompts on the electric vehicle control panel, or other forms.

[0067] The above descriptions are merely preferred embodiments of this application, and the present invention is not limited to the above embodiments. It is understood that other improvements and variations directly derived or conceived by those skilled in the art without departing from the spirit and concept of the present invention should be considered to be included within the protection scope of the present invention.

Claims

1. A method of monitoring state of health of a battery, the method comprising: The method comprises: Collecting battery cell voltage data every predetermined sampling time, calculating the cell voltage average value, the cell voltage maximum value and the cell voltage minimum value at each sampling time; Based on the battery cell voltage data and the cell voltage average value, the cell voltage dispersion at each sampling time is calculated; For each sampling time, when the maximum value of the single-unit voltage corresponds to SOC Vmax Corresponding to the minimum voltage of a single unit SOC Vmin When the difference is not less than a predetermined value, the minimum value of the individual voltage dispersion at that sampling time is deduced by using the maximum and minimum values ​​of the individual voltage. Comparing the cell voltage dispersion at each sampling time with the minimum cell voltage dispersion corresponding to the sampling time, the SOH of the lithium battery pack at this time is determined, if the cell voltage dispersion at each sampling time is not less than the minimum cell voltage dispersion corresponding to the sampling time, it is considered that the SOH of the lithium battery pack at this time is abnormal, otherwise it is considered that the SOH of the lithium battery pack at this time is normal; Wherein, the minimum cell voltage dispersion corresponding to the sampling time is inversely deduced by using the cell voltage maximum value and the cell voltage minimum value, comprising: ti The individual cell voltage dispersion at the sampling time is expressed as: ； in, m This refers to the number of battery cells in the lithium battery pack. , They are respectively represented as ti The maximum and minimum values ​​of the individual cell voltage at the sampling time; represents the average value of the cell voltages at the sampling instant, and ti represents the average value of the cell voltages at the sampling instant, and , V m,ti represents the cell voltage data of the i-th cell in the lithium battery at the sampling instant t; m represents the average value of the cell voltages at the sampling instant t, and ti represents the average value of the cell voltages at the sampling instant t, and represents the average value of the cell voltages at the sampling instant t, and ti represents the average value of the cell voltages at the sampling instant t, and , represents the average value of the cell voltages at the sampling instant t, and iff = 0 , has a minimum value, denoted by 。 2. The battery health monitoring method of claim 1, wherein, The cell voltage dispersion at each sampling time is calculated based on the battery cell voltage data and the cell voltage average value, and the expression is: 。 3. The battery health monitoring method of claim 1, wherein, The method further comprises: By looking up the SOC-OCV table of the single battery in the lithium battery pack, the maximum single battery voltage corresponding to SOC Vmax and the minimum single battery voltage corresponding to SOC Vmin .

4. An electric vehicle trunk, characterized by, The method comprises: The method comprises:

5. The electric vehicle trunk of claim 4, wherein, The battery monitoring module comprises a controller and a voltage acquisition circuit, a current acquisition circuit and an alarm circuit connected thereto; after the vehicle is parked, when the current acquisition circuit detects that the lithium battery pack current is zero, the voltage acquisition circuit collects battery cell voltage data every predetermined sampling time, the controller calculates the cell voltage dispersion at each sampling time based on the collected battery cell voltage data, thereby determining the SOH of the lithium battery pack; the alarm circuit is used for alarming when the SOH of the lithium battery pack is abnormal.

6. The electric vehicle trunk of claim 4, wherein, The lower cover is further provided with an inner recessed cavity, and the AC plug is accommodated in the inner recessed cavity, and the AC wire harness is orderly coiled in the lower cover shell below the lithium battery pack.

7. The electric vehicle trunk of claim 4, wherein, The upper cover and the lower cover are connected by a hinge, and a handle is installed on the top of the upper cover; the upper cover and the lower cover adopt a steel structure, and the inner surface is coated with an insulating material.

8. The electric vehicle trunk of claim 5, wherein, The battery monitoring module further comprises a temperature acquisition circuit connected to the controller, and the controller controls the on-off of the lithium battery pack and the charging module based on the collected battery temperature, thereby controlling the whole vehicle charging and discharging; the alarm circuit is used for alarming when the temperature of the lithium battery pack is abnormal.

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