A method, device and electronic equipment for charging and discharging lithium iron phosphate battery cells

Abstract

The present application provides a method, device and electronic device for adjusting the charge of lithium iron phosphate battery cells for shipment, the method comprising: obtaining the charge and discharge test data of the battery cells in the lithium iron phosphate battery pack to be grouped; determining the voltage platform interval of the battery cells according to the corresponding relationship between the charging voltage and the state of charge represented by the charge and discharge test data, and determining the state of charge at the end of the constant current and constant voltage step according to the endpoint value of the voltage platform interval; charging the battery cells with constant current and constant voltage to the state of charge at the end of the constant current and constant voltage step; and performing constant current charging / constant current discharging on the battery cells according to the difference between the state of charge at the end of the constant current and constant voltage step and the preset state of charge for shipment, so as to adjust the state of charge of the battery cells to the state of charge for shipment. By charging the battery cells with constant current and constant voltage to the voltage non-platform interval, the state of charge of all the battery cells in the lithium iron phosphate battery pack to be grouped is aligned after the constant current and constant voltage charging is completed, thereby ensuring the consistency of the state of charge of the lithium iron phosphate battery pack after the battery cells are grouped.

Description

Technical Field

[0001] The present application relates to the field of battery management technology, and in particular to a method, device and electronic equipment for charging and discharging lithium iron phosphate batteries. Background Art

[0002] At present, lithium iron phosphate batteries have been widely used in new energy vehicle battery packs. When new energy vehicle battery packs are shipped, the state of charge is generally adjusted to a specified range according to customer requirements. This process is called shipment load adjustment.

[0003] In the prior art, each battery cell constituting a battery pack is usually charged to a full charge state, and then a fixed amount of current is uniformly discharged.

[0004] However, due to differences in the manufacturing process of battery cells and the inability to ensure consistent ambient temperature during discharge, the battery cells may be incompletely discharged or over-discharged, and the charge state consistency of the lithium iron phosphate battery pack cannot be guaranteed after the battery cells are grouped. Summary of the invention

[0005] The present application provides a method, device and electronic equipment for charging and discharging lithium iron phosphate cells for shipment, so as to solve the defects of the prior art such as the inability to ensure the consistency of the charge state of the lithium iron phosphate battery pack after the cells are grouped.

[0006] The first aspect of the present application provides a method for charging and discharging a lithium iron phosphate battery cell, comprising:

[0007] Obtain the charge and discharge test data of the cells in the lithium iron phosphate battery pack to be assembled;

[0008] Determining a voltage platform interval of the battery cell according to a corresponding relationship between a charging voltage and a state of charge represented by the charging and discharging test data;

[0009] Determine the charge state at the end of the constant current and constant voltage step according to the endpoint value of the voltage platform interval; wherein the charge state at the end of the constant current and constant voltage step does not belong to the voltage platform interval;

[0010] Charging the battery cell with constant current and constant voltage until the constant current and constant voltage step is terminated and the charging state is reached;

[0011] According to the difference between the state of charge at the end of the constant current and constant voltage step and the preset shipping state of charge, the battery cell is charged with constant current / discharged with constant current to adjust the state of charge of the battery cell to the shipping state of charge.

[0012] Optionally, determining the voltage platform interval of the battery cell according to the corresponding relationship between the charging voltage and the state of charge represented by the charging and discharging test data includes:

[0013] Draw a charging curve of the battery cell according to the corresponding relationship between the charging voltage and the state of charge represented by the charging and discharging test data;

[0014] The voltage platform interval of the battery cell is determined according to the state of charge corresponding to the stable phase curve of the charging curve of the battery cell.

[0015] Optionally, determining the voltage platform interval of the battery cell according to the state of charge corresponding to the stable phase curve of the charging curve of the battery cell includes:

[0016] Determining the stable phase curve according to the slope corresponding to each point on the charging curve of the battery cell;

[0017] The charge states corresponding to the starting point and the ending point of the stable phase curve are determined as the endpoint values ​​of the voltage platform interval of the battery cell.

[0018] Optionally, the constant current charging / constant current discharging of the battery cell according to the difference between the charge state at the end of the constant current and constant voltage step and a preset delivery charge state includes:

[0019] Determining the required state of charge variable of the battery cell according to the difference between the state of charge at the end of the constant current and constant voltage step and the preset delivery state of charge;

[0020] Determining the charging time / discharging time of the battery cell according to the required state of charge variable of the battery cell and the rated current of constant current charging / constant current discharging;

[0021] According to the charging time / discharging time of the battery cell, the battery cell is subjected to constant current charging / constant current discharging for a corresponding duration.

[0022] Optionally, the step of obtaining charge and discharge test data of cells in a lithium iron phosphate battery pack to be assembled includes:

[0023] Based on the rated current, charging and discharging the battery cell;

[0024] The voltage data and the state of charge data during the charging and discharging process of the battery cell are recorded to obtain the charging and discharging test data of the battery cell.

[0025] Optionally, the constant current and constant voltage step cut-off state of charge is divided into a first constant current and constant voltage step cut-off state of charge and a second constant current and constant voltage step cut-off state of charge, the first constant current and constant voltage step cut-off state of charge is lower than the voltage platform interval, and the second constant current and constant voltage step cut-off state of charge is higher than the voltage platform interval, and the constant current and constant voltage charging of the battery cell to the constant current and constant voltage step cut-off state of charge includes:

[0026] The battery cell is charged at constant current and constant voltage until the first constant current and constant voltage step is terminated and the charged state is reached;

[0027] The constant current charging / constant current discharging of the battery cell according to the difference between the charge state at the end of the constant current and constant voltage step and the preset delivery charge state comprises:

[0028] The battery cell is charged with constant current according to the difference between the state of charge at the end of the first constant current and constant voltage step and a preset delivery state of charge.

[0029] Optionally, the step of charging the battery cell with constant current and constant voltage until the constant current and constant voltage step is terminated and the charging state is reached includes:

[0030] The battery cell is charged with constant current and constant voltage until the second constant current and constant voltage step is terminated and the charging state is reached;

[0031] The constant current charging / constant current discharging of the battery cell according to the difference between the charge state at the end of the constant current and constant voltage step and the preset delivery charge state comprises:

[0032] The battery cell is discharged at a constant current according to the difference between the charge state at the end of the second constant current and constant voltage step and a preset delivery charge state.

[0033] The second aspect of the present application provides a lithium iron phosphate battery cell shipping and charging adjustment device, comprising:

[0034] An acquisition module is used to acquire the charge and discharge test data of the cells in the lithium iron phosphate battery pack to be assembled;

[0035] A first determination module, configured to determine a voltage platform interval of the battery cell according to a corresponding relationship between a charging voltage and a state of charge represented by the charging and discharging test data;

[0036] A second determination module is used to determine the charge state at the end of the constant current and constant voltage step according to the endpoint value of the voltage platform interval; wherein the charge state at the end of the constant current and constant voltage step does not belong to the voltage platform interval;

[0037] A charging module, used for charging the battery cell with constant current and constant voltage to a charging state at which the constant current and constant voltage step is terminated;

[0038] The charge adjustment module is used to perform constant current charging / constant current discharging on the battery cell according to the difference between the charge state at the end of the constant current and constant voltage step and a preset shipping charge state, so as to adjust the charge state of the battery cell to the shipping charge state.

[0039] Optionally, the first determining module is specifically configured to:

[0040] Draw a charging curve of the battery cell according to the corresponding relationship between the charging voltage and the state of charge represented by the charging and discharging test data;

[0041] The voltage platform interval of the battery cell is determined according to the state of charge corresponding to the stable phase curve of the charging curve of the battery cell.

[0042] Optionally, the first determining module is specifically configured to:

[0043] Determining the stable phase curve according to the slope corresponding to each point on the charging curve of the battery cell;

[0044] The charge states corresponding to the starting point and the ending point of the stable phase curve are determined as the endpoint values ​​of the voltage platform interval of the battery cell.

[0045] Optionally, the load adjustment module is specifically used for:

[0046] Determining the required state of charge variable of the battery cell according to the difference between the state of charge at the end of the constant current and constant voltage step and the preset delivery state of charge;

[0047] Determining the charging time / discharging time of the battery cell according to the required state of charge variable of the battery cell and the rated current of constant current charging / constant current discharging;

[0048] According to the charging time / discharging time of the battery cell, the battery cell is subjected to constant current charging / constant current discharging for a corresponding duration.

[0049] Optionally, the acquisition module is specifically used to:

[0050] Based on the rated current, charging and discharging the battery cell;

[0051] The voltage data and the state of charge data during the charging and discharging process of the battery cell are recorded to obtain the charging and discharging test data of the battery cell.

[0052] Optionally, the constant current and constant voltage step cut-off state of charge is divided into a first constant current and constant voltage step cut-off state of charge and a second constant current and constant voltage step cut-off state of charge, the first constant current and constant voltage step cut-off state of charge is lower than the voltage platform interval, and the second constant current and constant voltage step cut-off state of charge is higher than the voltage platform interval, and the charging module is specifically used for:

[0053] The battery cell is charged at constant current and constant voltage until the first constant current and constant voltage step is terminated and the charged state is reached;

[0054] The load adjustment module is specifically used for:

[0055] The battery cell is charged with constant current according to the difference between the state of charge at the end of the first constant current and constant voltage step and a preset delivery state of charge.

[0056] Optionally, the charging module is specifically used for:

[0057] The battery cell is charged with constant current and constant voltage until the second constant current and constant voltage step is terminated and the charging state is reached;

[0058] The load adjustment module is specifically used for:

[0059] The battery cell is discharged at a constant current according to the difference between the charge state at the end of the second constant current and constant voltage step and a preset delivery charge state.

[0060] A third aspect of the present application provides an electronic device, comprising: at least one processor and a memory;

[0061] The memory stores computer-executable instructions;

[0062] The at least one processor executes the computer-executable instructions stored in the memory, so that the at least one processor performs the method described in the first aspect and various possible designs of the first aspect.

[0063] A fourth aspect of the present application provides a computer-readable storage medium, wherein the computer-readable storage medium stores computer-executable instructions. When a processor executes the computer-executable instructions, the method described in the first aspect and various possible designs of the first aspect are implemented.

[0064] The technical solution of this application has the following advantages:

[0065] The present application provides a method, device and electronic device for adjusting the charge for shipment of lithium iron phosphate cells, the method comprising: obtaining charge and discharge test data of cells in a lithium iron phosphate battery pack to be grouped; determining a voltage platform interval of the cells according to a correspondence between a charging voltage and a state of charge represented by the charge and discharge test data, and determining a constant current and constant voltage step cut-off state of charge according to an endpoint value of the voltage platform interval; wherein the constant current and constant voltage step cut-off state of charge does not belong to the voltage platform interval; charging the cells with constant current and constant voltage to a constant current and constant voltage step cut-off state of charge; and performing constant current charging / constant current discharging on the cells according to a difference between a constant current and constant voltage step cut-off state of charge and a preset shipment state of charge, so as to adjust the state of charge of the cells to a shipment state of charge. The method provided in the above scheme locates the voltage platform range of the battery cell, and then charges the battery cell with constant current and constant voltage to the voltage non-platform range, so that all the battery cells in the lithium iron phosphate battery pack to be grouped are aligned in charge state after the constant current and constant voltage charging is completed, thereby ensuring the consistency of the charge state of the lithium iron phosphate battery pack after the battery cells are grouped. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application, and a person skilled in the art can also obtain other drawings based on these drawings.

[0067] Figure 1 This is a structural schematic diagram of the lithium iron phosphate battery cell shipment and charge adjustment system based on the embodiment of the present application;

[0068] Figure 2 A schematic diagram of a flow chart of a method for adjusting the charge of lithium iron phosphate battery cells for shipment provided in an embodiment of the present application;

[0069] Figure 3 A schematic diagram of an exemplary charging curve provided in an embodiment of the present application;

[0070] Figure 4 A comparison chart of the charging results of the lithium iron phosphate battery cells shipped according to the embodiment of the present application;

[0071] Figure 5 A comparison chart of the discharge and constant current charging capacities of the battery cells provided in the embodiments of the present application under different temperature conditions;

[0072] Figure 6 A schematic diagram of the structure of a lithium iron phosphate battery cell shipping and charging adjustment device provided in an embodiment of the present application;

[0073] Figure 7 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application.

[0074] The above drawings have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the present disclosure in any way, but to illustrate the concepts of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0075] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0076] In addition, the terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. In the description of the following embodiments, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0077] In the prior art, each battery cell used to make up the battery pack is usually charged to a full charge state, and then a fixed amount of current is uniformly discharged. However, for battery cells whose positive electrodes are made of highly temperature-sensitive main materials, the space of the capacity division workshop is large and the temperature cannot be accurately controlled. That is, due to inconsistent ambient temperature during capacity division discharge, the battery cells may be incompletely discharged or over-discharged. At this time, the charge state of the battery cells after constant current charging will be quite different, and the charge state consistency of the lithium iron phosphate battery pack after the battery cells are grouped cannot be guaranteed. In addition, the capacity of the entire battery pack will be reduced after the battery cells are grouped.

[0078] In response to the above problems, the lithium iron phosphate battery cell shipment charge adjustment method, device and electronic equipment provided in the embodiments of the present application obtain the charge and discharge test data of the battery cells in the lithium iron phosphate battery pack to be grouped; determine the voltage platform range of the battery cells according to the correspondence between the charging voltage and the charge state represented by the charge and discharge test data, and determine the constant current and constant voltage step cut-off charge state according to the endpoint value of the voltage platform range; wherein the constant current and constant voltage step cut-off charge state does not belong to the voltage platform range; charge the battery cells with constant current and constant voltage to the constant current and constant voltage step cut-off charge state; and perform constant current charging / constant current discharging on the battery cells according to the difference between the constant current and constant voltage step cut-off charge state and the preset shipment charge state, so as to adjust the charge state of the battery cells to the shipment charge state. The method provided in the above scheme locates the voltage platform range of the battery cell, and then charges the battery cell with constant current and constant voltage to the voltage non-platform range, so that all the battery cells in the lithium iron phosphate battery pack to be grouped are aligned in charge state after the constant current and constant voltage charging is completed, thereby ensuring the consistency of the charge state of the lithium iron phosphate battery pack after the battery cells are grouped.

[0079] The following specific embodiments may be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments. The embodiments of the present invention will be described below in conjunction with the accompanying drawings.

[0080] First, the structure of the lithium iron phosphate battery cell shipment and charge adjustment system based on this application is described:

[0081] The method, device and electronic device for charging and shipping lithium iron phosphate cells provided in the embodiments of the present application are suitable for charging and shipping lithium iron phosphate cells used to form lithium iron phosphate battery packs. Figure 1The figure shows a schematic diagram of the structure of the lithium iron phosphate battery cell shipment and charge adjustment system based on the embodiment of the present application, which mainly includes a battery cell, a data acquisition device, and a lithium iron phosphate battery cell shipment and charge adjustment device for shipment and charge adjustment. Specifically, the charge and discharge test data of the battery cell can be collected based on the data acquisition device, and then the collected data can be sent to the lithium iron phosphate battery cell shipment and charge adjustment device. The device determines the charge state of the constant current and constant voltage step cutoff of the charge based on the obtained data, and then performs the corresponding shipment and charge adjustment operation on it.

[0082] The embodiment of the present application provides a method for adjusting the charge of lithium iron phosphate battery cells for shipment, which is used to adjust the charge of lithium iron phosphate battery cells used to form a lithium iron phosphate battery pack. The execution subject of the embodiment of the present application is an electronic device, such as a server, a desktop computer, a laptop computer, a tablet computer, and other electronic devices that can be used to control the charge adjustment of lithium iron phosphate battery cells for shipment.

[0083] like Figure 2 As shown, it is a flow chart of the method for charging and discharging lithium iron phosphate batteries provided in an embodiment of the present application, and the method includes:

[0084] Step 201, obtaining charge and discharge test data of the battery cells in the lithium iron phosphate battery pack to be assembled.

[0085] Step 202: Determine the voltage platform interval of the battery cell according to the corresponding relationship between the charging voltage and the state of charge represented by the charge and discharge test data.

[0086] It should be noted that the voltage platform range refers to the range where the charging voltage hardly increases with the increase of the state of charge SOC, such as the state of charge in the range of 20% to 80%. Since all the cells that make up the same lithium iron phosphate battery pack use the same positive and negative electrode materials and electrolytes, the voltage platform range of all cells is also the same.

[0087] Step 203, determining the charge state at the end of the constant current and constant voltage step according to the endpoint value of the voltage platform interval.

[0088] Among them, the charging state at the end of the constant current and constant voltage step does not belong to the voltage platform range.

[0089] Exemplarily, when the endpoint values ​​of the voltage platform interval are 20% and 80%, the charge state at the end of the constant current and constant voltage step can be determined within the range of 0-20% or 80%-100%.

[0090] It should be noted that the range of 0-20% and 80-100% can be referred to as a voltage non-platform interval. In the voltage non-platform interval, the charging voltage increases significantly as the state of charge SOC increases.

[0091] Step 204, charging the battery cell with constant current and constant voltage until the constant current and constant voltage step is terminated.

[0092] Specifically, if all cells in the grouped lithium iron phosphate battery pack are charged with constant current and constant voltage to the charge state at the end of the constant current and constant voltage step, that is, charged with constant current and constant voltage to the voltage non-platform area of ​​the cell, it can ensure that the charge state of all cells is truly aligned at the end of constant current and constant voltage charging.

[0093] Step 205 , performing constant current charging / constant current discharging on the battery cell according to the difference between the state of charge at the end of the constant current and constant voltage step and the preset delivery state of charge, so as to adjust the state of charge of the battery cell to the delivery state of charge.

[0094] It should be noted that the preset shipping state of charge is the shipping state of charge required by the customer, and the shipping state of charge belongs to the voltage platform range of the battery cell.

[0095] Specifically, according to the difference between the cut-off state of charge of the constant current and constant voltage step and the preset delivery state of charge, the battery cell can be charged / discharged at a corresponding capacity at a constant current to achieve the delivery state of charge required by the customer.

[0096] It should be further explained that a lithium iron phosphate battery pack may include cells of various capacity specifications. After the cells are grouped after the charge adjustment method for lithium iron phosphate battery shipment provided in the embodiment of the present application is adjusted, the consistency of the state of charge of each cell is ensured, such as the state of charge of all cells is consistent at 50%, which is conducive to the use of the capacity of the entire battery pack after the cells are grouped. In addition, when charging the grouped lithium iron phosphate battery pack, only the cells with the lowest capacity specification will go through the full charge and discharge state, while the other cells will only experience the shallow charge and discharge state, which is conducive to protecting other cells. In addition, when the polarization of the cell with a higher capacity increases due to loose connection and other reasons, that is, the voltage rises quickly during the charging process, it may happen that the state of charge does not reach 100% and the charging stops in advance because the voltage reaches the stop charging threshold. The cell can use its capacity advantage to make up for its lack of polarization.

[0097] Among them, the constant current and constant voltage step cut-off charging state can be divided into a first constant current and constant voltage step cut-off charging state and a second constant current and constant voltage step cut-off charging state. The first constant current and constant voltage step cut-off charging state is lower than the voltage platform interval, and the second constant current and constant voltage step cut-off charging state is higher than the voltage platform interval.

[0098] Specifically, in one embodiment, the battery cell can be charged with constant current and constant voltage to the charge state at the end of the first constant current and constant voltage step; and the battery cell is charged with constant current according to the difference between the charge state at the end of the first constant current and constant voltage step and the preset shipping charge state.

[0099] Accordingly, in one embodiment, the battery cell can be charged with constant current and constant voltage to the charge state at the end of the second constant current and constant voltage step; and the battery cell is discharged with constant current according to the difference between the charge state at the end of the second constant current and constant voltage step and the preset shipping charge state.

[0100] Exemplarily, when the voltage platform interval is 20% to 80%, the charge state at the end of the first constant current and constant voltage step belongs to the voltage non-platform interval 0 to 20%, and the charge state at the end of the second constant current and constant voltage step belongs to the voltage non-platform interval 80%-100%.

[0101] Based on the above embodiment, as an implementable manner, in one embodiment, according to the corresponding relationship between the charging voltage and the state of charge represented by the charging and discharging test data, the voltage platform interval of the battery cell is determined, including:

[0102] Step 2021, drawing a charging curve of the battery cell according to the corresponding relationship between the charging voltage and the state of charge represented by the charging and discharging test data;

[0103] Step 2022: Determine the voltage platform interval of the battery cell according to the state of charge corresponding to the stable phase curve of the charging curve of the battery cell.

[0104] For example, Figure 3 , which is a schematic diagram of an exemplary charging curve provided in an embodiment of the present application, Figure 3 The curve corresponding to the 8% to 96% stage on the charging curve shown is its stable stage curve. Accordingly, 8% to 96% can be determined as the voltage platform area of ​​the battery cell. Figure 3 The SOC in it is the state of charge, and the voltage is the charging voltage.

[0105] Specifically, in one embodiment, a steady phase curve can be determined based on the slope corresponding to each point on the charging curve of the battery cell; the charge states corresponding to the starting point and the ending point of the steady phase curve are determined as the endpoint values ​​of the voltage platform interval of the battery cell.

[0106] Similarly, in one embodiment, the state of charge corresponding to the starting point and the end point of the stable phase curve can be determined according to the peak value of the dQ / dV differential calculation result corresponding to the charging curve of the battery cell. Q represents the state of charge, and V represents the charging voltage. The state of charge corresponding to the starting point and the end point of the stable phase curve is then determined as the left and right endpoint values ​​of the voltage platform interval of the battery cell.

[0107] On the basis of the above embodiment, in order to facilitate the shipment and charge adjustment of the lithium iron phosphate battery cell, as an implementable method, in one embodiment, according to the difference between the cut-off state of charge of the constant current and constant voltage step and the preset shipment state of charge, the battery cell is subjected to constant current charging / constant current discharging, including:

[0108] Step 2051, determining the required state of charge variable of the battery cell according to the difference between the state of charge at the end of the constant current and constant voltage step and the preset delivery state of charge;

[0109] Step 2052, determining the charging time / discharging time of the battery cell according to the required state of charge variable of the battery cell and the rated current of constant current charging / constant current discharging;

[0110] Step 2053: Perform constant current charging / constant current discharging of the battery cell for a corresponding duration according to the charging time / discharging time of the battery cell.

[0111] The required variable of the state of charge of the battery cell is the amount to be charged or discharged, and the rated current of constant current charging / constant current discharging is the rated current required by the customer.

[0112] Specifically, the charging time / discharging time of the battery cell can be determined according to the ratio of the required state of charge variable to the rated current of constant current charging / constant current discharging, and then the state of charge of the battery cell can be adjusted to the shipping state of charge by controlling the duration of the constant current charging / constant current discharging.

[0113] Accordingly, in one embodiment, the battery cell may be charged and discharged based on the rated current; and the voltage data and the state of charge data during the charging and discharging process of the battery cell may be recorded to obtain the charging and discharging test data of the battery cell.

[0114] Specifically, the battery cell can be charged and discharged based on the rated current used for charge regulation, and then the voltage data and charge state data during the charging and discharging process can be recorded to obtain complete charging and discharging test data of the battery cell.

[0115] In order to facilitate those skilled in the art to clearly understand the progress of the lithium iron phosphate battery cell shipment charge adjustment method provided in this application relative to the prior art, as Figure 4 The figure shows a comparison of the results of the shipping and charging adjustment of the lithium iron phosphate battery provided in the embodiment of the present application. The first row adopts the shipping and charging adjustment method of constant current discharge after full charge, the second row adopts the shipping and charging adjustment method of constant current charging after emptying, and the third row adopts the shipping and charging adjustment method provided in the embodiment of the present application. Figure 4 The two paired bar graphs of different heights represent the high-capacity cells and the low-capacity cells in the lithium iron phosphate battery pack. From the comparison of the three rows, it can be seen that, relative to the prior art, with the shipment debugging method provided in the embodiment of the present application, only the cell with the lowest capacity in the entire lithium iron phosphate battery pack will experience the states of being fully charged and discharged, while other cells will not experience the states of being completely discharged and fully charged. This is a protection for other cells with higher capacities. In addition, when the polarization of the cells with higher capacity increases due to connection and other reasons, they can make up for the lack of polarization increase through their capacity advantage, so as to ensure that the capacity of the entire lithium iron phosphate battery pack does not decay.

[0116] Furthermore, the impact of ambient temperature changes on the loading results of lithium iron phosphate battery shipments is studied. Figure 5 As shown, it is a comparison chart of the discharge and constant current charging capacity of the battery cell provided in the embodiment of the present application under different temperature conditions. The same battery cell is selected to be fully charged and discharged at 25°C and 16°C respectively. The discharge capacity at 25°C is 1.329Ah more than that at 16°C, that is, the discharge at 16°C is incomplete, and the capacity is 5.3% less than that at 25°C. When the battery cell is charged to 0-20% SOC (voltage non-platform range) at constant current and constant voltage based on the shipment adjustment method provided in the embodiment of the present application at 16°C and 25°C in the next step of discharge, 16°C is charged 1.36Ah less than 25°C, that is, the capacity that is less discharged during discharge at 16°C can be compensated during constant current and constant voltage charging. After constant current and constant voltage charging, the SOC of the battery cell is truly aligned.

[0117] The embodiment of the present application provides a method for adjusting the charge for shipment of lithium iron phosphate cells, by acquiring charge and discharge test data of the cells in the lithium iron phosphate battery pack to be grouped; determining the voltage platform interval of the cells according to the corresponding relationship between the charging voltage and the state of charge represented by the charge and discharge test data, and determining the constant current and constant voltage step cut-off state of charge according to the endpoint value of the voltage platform interval; wherein the constant current and constant voltage step cut-off state of charge does not belong to the voltage platform interval; charging the cells with constant current and constant voltage to the constant current and constant voltage step cut-off state of charge; and performing constant current charging / constant current discharging on the cells according to the difference between the constant current and constant voltage step cut-off state of charge and a preset shipment state of charge, so as to adjust the state of charge of the cells to the shipment state of charge. The method provided by the above scheme locates the voltage platform range of the battery cell, and then charges the battery cell with constant current and constant voltage to the voltage non-platform range, so that all the batteries in the lithium iron phosphate battery pack to be grouped can achieve charge state alignment after constant current and constant voltage charging, ensuring the consistency of the charge state of the lithium iron phosphate battery pack after the battery cells are grouped, thereby improving the capacity of the lithium iron phosphate battery pack. In addition, when the temperature fluctuation of the divided capacity environment causes incomplete discharge or over-discharge of the battery cell, it can be charged to the non-platform area by constant current and constant voltage, which can compensate for the error caused by the ambient temperature.

[0118] An embodiment of the present application provides a lithium iron phosphate battery cell shipping and charging adjustment device, which is used to execute the lithium iron phosphate battery cell shipping and charging adjustment method provided in the above embodiment.

[0119] like Figure 6 , which is a schematic diagram of a lithium iron phosphate battery cell shipping and charging adjustment device provided in an embodiment of the present application. The lithium iron phosphate battery cell shipping and charging adjustment device 60 comprises: an acquisition module 601, a first determination module 602, a second determination module 603, a charging module 604 and a charging adjustment module 605.

[0120] Among them, the acquisition module is used to obtain the charge and discharge test data of the battery cells in the lithium iron phosphate battery pack to be grouped; the first determination module is used to determine the voltage platform range of the battery cells according to the corresponding relationship between the charging voltage and the state of charge represented by the charge and discharge test data; the second determination module is used to determine the constant current and constant voltage step cut-off state of charge according to the endpoint value of the voltage platform range; wherein the constant current and constant voltage step cut-off state of charge does not belong to the voltage platform range; the charging module is used to charge the battery cells with constant current and constant voltage to the constant current and constant voltage step cut-off state of charge; the charge adjustment module is used to perform constant current charging / constant current discharging on the battery cells according to the difference between the constant current and constant voltage step cut-off state of charge and the preset shipping state of charge, so as to adjust the state of charge of the battery cells to the shipping state of charge.

[0121] Specifically, in one embodiment, the first determining module is specifically configured to:

[0122] Draw the charging curve of the battery cell according to the corresponding relationship between the charging voltage and the state of charge represented by the charging and discharging test data;

[0123] The voltage platform range of the battery cell is determined according to the charge state corresponding to the stable phase curve of the charging curve of the battery cell.

[0124] Specifically, in one embodiment, the first determining module is specifically configured to:

[0125] Determine the stable phase curve according to the slope corresponding to each point on the charging curve of the battery cell;

[0126] The charge states corresponding to the starting point and the end point of the stable phase curve are determined as the endpoint values ​​of the voltage platform interval of the battery cell.

[0127] Specifically, in one embodiment, the load adjustment module is specifically used to:

[0128] Determine the required state of charge variable of the battery cell according to the difference between the state of charge at the end of the constant current and constant voltage process step and the preset state of charge for shipment;

[0129] Determine the charging time / discharging time of the battery cell according to the required state of charge of the battery cell and the rated current of constant current charging / constant current discharging;

[0130] According to the charging time / discharging time of the battery cell, the battery cell is charged / discharged at a constant current for a corresponding period of time.

[0131] Specifically, in one embodiment, the acquisition module is specifically used to:

[0132] Based on the rated current, the battery cell is charged and discharged;

[0133] The voltage data and charge state data during the charging and discharging process of the battery cell are recorded to obtain the charging and discharging test data of the battery cell.

[0134] Specifically, in one embodiment, the constant current and constant voltage step cut-off charging state is divided into a first constant current and constant voltage step cut-off charging state and a second constant current and constant voltage step cut-off charging state, the first constant current and constant voltage step cut-off charging state is lower than the voltage platform interval, and the second constant current and constant voltage step cut-off charging state is higher than the voltage platform interval. The charging module is specifically used for:

[0135] The battery cell is charged at constant current and constant voltage until the first constant current and constant voltage step is terminated and the charging state is reached;

[0136] Load adjustment module, specifically used for:

[0137] The battery cell is charged with constant current according to the difference between the state of charge at the end of the first constant current and constant voltage process step and the preset delivery state of charge.

[0138] Specifically, in one embodiment, the charging module is specifically used for:

[0139] The battery cell is charged at constant current and constant voltage until the second constant current and constant voltage step is terminated and the charging state is reached;

[0140] Load adjustment module, specifically used for:

[0141] The battery cell is discharged at a constant current according to the difference between the charge state at the end of the second constant current and constant voltage process step and the preset delivery charge state.

[0142] Regarding the lithium iron phosphate battery cell shipment charge adjustment device in this embodiment, the specific manner in which each module performs the operation has been described in detail in the embodiment of the method, and will not be elaborated here.

[0143] The lithium iron phosphate battery cell shipping and charging adjustment device provided in the embodiment of the present application is used to execute the lithium iron phosphate battery cell shipping and charging adjustment method provided in the above embodiment. Its implementation method and principle are the same and will not be repeated here.

[0144] An embodiment of the present application provides an electronic device for executing the method for charging and shipping of lithium iron phosphate batteries provided in the above embodiment.

[0145] like Figure 7 FIG. 7 is a schematic diagram of the structure of an electronic device provided in an embodiment of the present application. The electronic device 70 includes: at least one processor 71 and a memory 72 .

[0146] The memory stores computer-executable instructions; at least one processor executes the computer-executable instructions stored in the memory, so that the at least one processor executes the lithium iron phosphate battery cell shipment and charge adjustment method provided in the above embodiment.

[0147] An electronic device provided in an embodiment of the present application is used to execute the method for adjusting the charge of lithium iron phosphate battery cells shipped provided in the above embodiment. The implementation method and principle are the same and will not be repeated here.

[0148] An embodiment of the present application provides a computer-readable storage medium, in which computer-executable instructions are stored. When a processor executes the computer-executable instructions, the method for charging and shipping lithium iron phosphate batteries provided in any of the above embodiments is implemented.

[0149] The storage medium containing computer executable instructions in the embodiment of the present application can be used to store computer executable instructions of the lithium iron phosphate battery cell shipping and charge adjustment method provided in the aforementioned embodiment. Its implementation method and principle are the same and will not be repeated here.

[0150] In the several embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0151] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0152] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of hardware plus software functional units.

[0153] The above-mentioned integrated unit implemented in the form of a software functional unit can be stored in a computer-readable storage medium. The above-mentioned software functional unit is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) or a processor to perform some steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), disk or optical disk and other media that can store program code.

[0154] Those skilled in the art can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional modules is used as an example for illustration. In actual applications, the above-mentioned functions can be assigned to different functional modules as needed, that is, the internal structure of the device is divided into different functional modules to complete all or part of the functions described above. The specific working process of the device described above can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here.

[0155] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for charging and discharging lithium iron phosphate batteries, characterized in that: include: Obtain the charge and discharge test data of the cells in the lithium iron phosphate battery pack to be assembled; Determining a voltage platform interval of the battery cell according to a corresponding relationship between a charging voltage and a state of charge represented by the charging and discharging test data; Determine the charge state at the end of the constant current and constant voltage step according to the endpoint value of the voltage platform interval; wherein the charge state at the end of the constant current and constant voltage step does not belong to the voltage platform interval; Charging the battery cell with constant current and constant voltage until the constant current and constant voltage step is terminated and the charging state is reached; According to the difference between the state of charge at the end of the constant current and constant voltage step and the preset delivery state of charge, the battery cell is subjected to constant current charging / constant current discharging to adjust the state of charge of the battery cell to the delivery state of charge; The determining the voltage platform interval of the battery cell according to the corresponding relationship between the charging voltage and the state of charge represented by the charging and discharging test data includes: Draw a charging curve of the battery cell according to the corresponding relationship between the charging voltage and the state of charge represented by the charging and discharging test data; Determining a voltage platform interval of the battery cell according to a state of charge corresponding to a stable phase curve of a charging curve of the battery cell; The step of determining the voltage platform interval of the battery cell according to the state of charge corresponding to the stable phase curve of the charging curve of the battery cell comprises: Determining the stable phase curve according to the slope corresponding to each point on the charging curve of the battery cell; The charge states corresponding to the starting point and the ending point of the stable phase curve are determined as the endpoint values ​​of the voltage platform interval of the battery cell.

2. The method according to claim 1, characterized in that: The constant current charging / constant current discharging of the battery cell according to the difference between the charge state at the end of the constant current and constant voltage step and the preset delivery charge state comprises: Determining the required state of charge variable of the battery cell according to the difference between the state of charge at the end of the constant current and constant voltage step and the preset delivery state of charge; Determining the charging time / discharging time of the battery cell according to the required state of charge variable of the battery cell and the rated current of constant current charging / constant current discharging; According to the charging time / discharging time of the battery cell, the battery cell is subjected to constant current charging / constant current discharging for a corresponding duration.

3. The method according to claim 2, characterized in that The step of obtaining the charge and discharge test data of the cells in the lithium iron phosphate battery pack to be assembled comprises: Based on the rated current, charging and discharging the battery cell; The voltage data and the state of charge data during the charging and discharging process of the battery cell are recorded to obtain the charging and discharging test data of the battery cell.

4. The method according to claim 1, characterized in that The constant current and constant voltage step end state of charge is divided into a first constant current and constant voltage step end state of charge and a second constant current and constant voltage step end state of charge, the first constant current and constant voltage step end state of charge is lower than the voltage platform interval, the second constant current and constant voltage step end state of charge is higher than the voltage platform interval, and the constant current and constant voltage charging of the battery cell to the constant current and constant voltage step end state of charge includes: The battery cell is charged at constant current and constant voltage until the first constant current and constant voltage step is terminated and the charged state is reached; The constant current charging / constant current discharging of the battery cell according to the difference between the charge state at the end of the constant current and constant voltage step and the preset delivery charge state comprises: The battery cell is charged with constant current according to the difference between the state of charge at the end of the first constant current and constant voltage step and a preset delivery state of charge.

5. The method according to claim 4, characterized in that The step of charging the battery cell with constant current and constant voltage until the constant current and constant voltage step is terminated and the charging state is completed includes: The battery cell is charged with constant current and constant voltage until the second constant current and constant voltage step is terminated and the charging state is reached; The constant current charging / constant current discharging of the battery cell according to the difference between the charge state at the end of the constant current and constant voltage step and the preset delivery charge state comprises: The battery cell is discharged at a constant current according to the difference between the charge state at the end of the second constant current and constant voltage step and a preset delivery charge state.

6. A charging adjustment device for lithium iron phosphate battery shipment, characterized in that: include: An acquisition module is used to acquire the charge and discharge test data of the cells in the lithium iron phosphate battery pack to be assembled; A first determination module, configured to determine a voltage platform interval of the battery cell according to a corresponding relationship between a charging voltage and a state of charge represented by the charging and discharging test data; A second determination module is used to determine the charge state at the end of the constant current and constant voltage step according to the endpoint value of the voltage platform interval; wherein the charge state at the end of the constant current and constant voltage step does not belong to the voltage platform interval; A charging module, used for charging the battery cell with constant current and constant voltage to a charging state at which the constant current and constant voltage step is terminated; A charge adjustment module, used for performing constant current charging / constant current discharging on the battery cell according to the difference between the charge state at the end of the constant current and constant voltage step and a preset delivery charge state, so as to adjust the charge state of the battery cell to the delivery charge state; The first determining module is specifically configured to: Draw a charging curve of the battery cell according to the corresponding relationship between the charging voltage and the state of charge represented by the charging and discharging test data; Determining a voltage platform interval of the battery cell according to a state of charge corresponding to a stable phase curve of a charging curve of the battery cell; The first determining module is specifically configured to: Determining the stable phase curve according to the slope corresponding to each point on the charging curve of the battery cell; The charge states corresponding to the starting point and the ending point of the stable phase curve are determined as the endpoint values ​​of the voltage platform interval of the battery cell.

7. An electronic device, characterized in that: include: at least one processor and memory; The memory stores computer-executable instructions; The at least one processor executes the computer-executable instructions stored in the memory, so that the at least one processor performs the method according to any one of claims 1 to 5.

8. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer-executable instructions, and when the processor executes the computer-executable instructions, the method according to any one of claims 1 to 5 is implemented.

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