Battery soc dynamic correction method and system, and vehicle with same

Abstract

The application provides a battery SOC dynamic correction method and system and a vehicle with the same. The battery SOC dynamic correction method comprises the following steps: judging a display SOC range; and adjusting a correction rate of the SOC by increasing or reducing a current according to the display SOC range, so that the display SOC is equal to a real SOC. According to the battery SOC dynamic correction method, different correction rates can be adopted in different SOC ranges according to the real SOC characteristics of the battery and actual charging and discharging use conditions, so that the display SOC of the large charging and discharging power type battery is more accurate.

Description

Technical Field

[0001] This invention relates to the field of new energy battery technology, specifically to a method, system, and vehicle having the same for dynamic correction of battery SOC. Background Technology

[0002] The development of automobiles has evolved from a purely gasoline-powered stage to a new energy era of hybrid and pure electric vehicles. A certain mild hybrid project utilizes a 2.0T + 48V mild hybrid powertrain. Introducing a mild hybrid system can compensate for the delay in turbocharger engagement; furthermore, the torque output from the IBSG allows the engine to operate closer to the enrichment line, keeping it in its high-efficiency range and reducing fuel consumption and carbon emissions. Therefore, the state of the 48V lithium battery in the mild hybrid system is crucial to the system's operation.

[0003] The key parameter characterizing the performance of a lithium battery is its state of charge (SOC). The lithium battery used in the mild hybrid system is a 1-parallel, 14-series lithium iron phosphate cell, characterized by its low capacity (0.4 kWh) and high charging / discharging power (13 kW instantaneously). Since the SOC of lithium batteries fluctuates significantly during use, accurately reflecting the SOC is crucial.

[0004] Lithium-ion battery SOC is divided into displayed SOC and true SOC. True SOC represents the actual state of charge of the battery and can be obtained by looking up a table using the OCV curve based on the cell's internal resistance and voltage change characteristics. However, using the OCV curve for table lookup requires that the cell be at rest and without charging or discharging current. In actual use of lithium-ion batteries, it is difficult to meet these conditions. In practice, the displayed SOC is generally calculated by integrating the ampere-hours based on the actual charging and discharging current. However, the ampere-hour integration is affected by the sampling accuracy of the current sensor and the superposition error of the integration algorithm, resulting in a discrepancy between the true SOC and the displayed SOC. Summary of the Invention

[0005] The technical problem to be solved by the embodiments of the present invention is that there is a large deviation between the displayed SOC and the actual SOC, and it is difficult to correct.

[0006] In view of this, the present invention provides a method for dynamic correction of battery SOC, comprising the following steps:

[0007] Determine the range of the displayed SOC;

[0008] Based on the range of the displayed SOC, the correction rate of SOC is adjusted by increasing or decreasing the current so that the displayed SOC equals the true SOC.

[0009] The battery SOC dynamic correction method according to embodiments of the present invention may further include the following technical features:

[0010] Furthermore, if the display SOC ≤ 35%, the correction rate is 5%; if 35% < display SOC ≤ 45%, the correction rate is 2%; if 45% < display SOC < 75%, the correction rate is 1%; if 75% ≤ display SOC < 85%, the correction rate is 2%; and if the display SOC ≥ 85%, the correction rate is 5%.

[0011] A battery SOC dynamic correction system according to a second aspect of the present invention includes:

[0012] The judgment module is used to determine the range of the displayed SOC;

[0013] A correction module, connected to the judgment module, adjusts the correction rate of the displayed SOC by increasing or decreasing the current according to the range of the displayed SOC, so that the displayed SOC is equal to the true SOC.

[0014] Furthermore, if the display SOC ≤ 35%, the correction rate is 5%; if 35% < display SOC ≤ 45%, the correction rate is 2%; if 45% < display SOC < 75%, the correction rate is 1%; if 75% ≤ display SOC < 85%, the correction rate is 2%; and if the display SOC ≥ 85%, the correction rate is 5%.

[0015] The vehicle according to the second aspect of the present invention includes the battery SOC dynamic correction system described in the above embodiments.

[0016] The above-described technical solution of the present invention has at least the following technical effects:

[0017] According to the battery SOC dynamic correction method of the present invention, different correction rates can be adopted in different SOC ranges based on the battery's true SOC characteristics and actual charging and discharging usage, making the displayed SOC of high-charge and high-discharge power batteries more accurate. Attached Figure Description

[0018] Figure 1 This is a flowchart of a battery SOC dynamic correction method according to an embodiment of the present invention;

[0019] Figure 2 This is an OCV curve diagram according to an embodiment of the present invention;

[0020] Figure 3 This is a SOC curve diagram according to an embodiment of the present invention;

[0021] Figure 4 This is a schematic diagram of a battery SOC dynamic correction system according to an embodiment of the present invention.

[0022] Figure Labels

[0023] Battery SOC dynamic correction system 100; judgment module 10; correction module 20. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0025] The battery SOC dynamic correction method according to an embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

[0026] like Figure 1 As shown, the battery SOC dynamic correction method according to an embodiment of the present invention includes the following steps:

[0027] S10. Determine the range of the displayed SOC;

[0028] S20. Based on the range of the displayed SOC, adjust the correction rate of SOC by increasing or decreasing the current so that the displayed SOC equals the true SOC.

[0029] Specifically, such as Figure 2 As shown, the battery is charged and discharged based on the characteristic points of the OCV curve. The correction rate of the displayed SOC is adjusted according to the range of the displayed SOC. The corrected displayed SOC is fed back to the 48V system through the BMS. The system makes a charge and discharge judgment based on the corrected battery SOC.

[0030] Therefore, the battery SOC dynamic correction method according to the present invention can adopt different correction rates in different SOC ranges according to the battery's true SOC characteristics and actual charging and discharging usage, making the displayed SOC of high-charge and high-discharge power batteries more accurate.

[0031] In one embodiment of the present invention, in step S20, if the displayed SOC ≤ 35%, the correction rate is 5%; if 35% < displayed SOC ≤ 45%, the correction rate is 2%; if 45% < displayed SOC < 75%, the correction rate is 1%; if 75% ≤ displayed SOC < 85%, the correction rate is 2%; and if the displayed SOC ≥ 85%, the correction rate is 5%. The larger correction rate is used for the endpoint of the displayed SOC. Figure 3As shown, the graph displays the trends of SOC, true SOC, and corrected displayed SOC (i.e., target corrected SOC) over time. The left vertical axis represents the displayed SOC, and the right vertical axis represents the true SOC and the corrected displayed SOC. As can be seen from the graph, the corrected displayed SOC is closer to the true SOC.

[0032] In other words, the usable SOC range in a mild hybrid system is between 35% and 85%. Consulting the OCV table reveals that within this range, cell voltage fluctuations are minimal, meaning open-circuit voltage changes are small. Voltage fluctuations at this point lead to significant changes in the corresponding SOC. Therefore, dynamic correction of the displayed SOC should be performed in segments to minimize errors at high and low SOC levels. Taking lithium iron phosphate (LFP) cells as an example, the voltage range of LFP cells is 2.5V to 3.65V. When the voltage range is between 3.29V and 3.31V, the OCV curve of the LFP cell is relatively flat, making it difficult to select characteristic points and correct the displayed SOC. Therefore, different correction rates are used within different SOC ranges based on the battery's true SOC characteristics and actual charge / discharge usage. The true SOC is calculated using a battery model, combining sampled signals from within the battery pack, including voltage, current, and temperature values, with the chemical model of the LFP cell. The true SOC is an internal quantity of the battery pack itself. The displayed SOC is a filtered value of the actual SOC that is reported to other controllers; for the battery, it is an external quantity.

[0033] According to one embodiment of the present invention, the displayed SOC is 35% and the actual SOC is 50%. Because the displayed SOC is 35%, the battery is charged. At this time, the charging current is large, and the displayed SOC catches up with the actual SOC at a rate of 5% / s. After 3s, the displayed SOC reaches 50%. During this period, since the actual SOC is also changing, after the displayed SOC reaches 50%, it catches up with the actual SOC after another 1s.

[0034] According to another embodiment of the present invention, the displayed SOC is 45% and the actual SOC is 50%. When the battery is being charged, the charging current is small, and the displayed SOC catches up at a rate of 1% / s. It can catch up in 5 seconds. At 3 seconds, the vehicle's demand changes from charging to discharging. At this time, the displayed SOC is 48% and the actual SOC is 51%. The discharging current is large, and the correction rate changes from 1% to 2%. After 2 seconds, the displayed SOC and the actual SOC can catch up. During the charging and discharging conversion process, the magnitude of the charging and discharging current changes, and the catching-up rate also changes.

[0035] In summary, the battery SOC dynamic correction method according to embodiments of the present invention can adopt different correction rates in different SOC ranges based on the battery's true SOC characteristics and actual charging and discharging usage, making the displayed SOC of high-charge-discharge power batteries more accurate.

[0036] According to a second aspect of the present invention, a battery SOC dynamic correction system 100 includes a judgment module 10 and a correction module 20.

[0037] Specifically, such as Figure 4 As shown, the judgment module 10 is used to determine the range of the displayed SOC. The correction module 20 is connected to the judgment module 10. The correction module 20 adjusts the correction rate of SOC by increasing or decreasing the current according to the range of the displayed SOC so that the displayed SOC is equal to the true SOC.

[0038] Specifically, the judgment module 10 is used to determine the range of the displayed SOC, and the correction module 20 controls the charging and discharging of the battery based on the characteristic points of the OCV curve. For different ranges of the displayed SOC, the correction rate of SOC is adjusted. The corrected displayed SOC is fed back to the 48V system through the BMS, and the system makes a charging and discharging judgment based on the corrected battery SOC.

[0039] Preferably, if the displayed SOC ≤ 35%, the correction rate is 5%; if 35% < displayed SOC ≤ 45%, the correction rate is 2%; if 45% < displayed SOC < 75%, the correction rate is 1%; if 75% ≤ displayed SOC < 85%, the correction rate is 2%; and if displayed SOC ≥ 85%, the correction rate is 5%. The larger correction rate is applied to the endpoints of the displayed SOC.

[0040] In summary, the battery SOC dynamic correction system 100 according to the embodiments of the present invention can adopt different correction rates in different SOC ranges according to the actual SOC characteristics of the battery and the actual charging and discharging usage, so as to make the displayed SOC of high charging and discharging power batteries more accurate.

[0041] In another embodiment of the present invention, a vehicle including the battery SOC dynamic correction system 100 of the above embodiments is also provided. Since the battery SOC dynamic correction system 100 of the above embodiments of the present invention has the above-mentioned technical effects, the vehicle of the present invention also has the corresponding technical effects, that is, it can adopt different correction rates in different SOC ranges according to the actual SOC characteristics of the battery and the actual charging and discharging usage, so that the displayed SOC of the high charging and discharging power battery is more accurate.

[0042] Other structures and operations of the vehicle according to embodiments of the present invention are understandable and readily implemented by those skilled in the art, and therefore will not be described in detail.

[0043] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship also changes accordingly.

[0044] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for dynamic correction of battery SOC, characterized in that, Includes the following steps: Determine the range of the displayed SOC; Based on the range of the displayed SOC, the correction rate of SOC is adjusted by increasing or decreasing the current to make the displayed SOC equal to the true SOC; If the displayed SOC is ≤ 35%, the correction rate is 5%; if 35% < displayed SOC ≤ 45%, the correction rate is 2%; if 45% < displayed SOC < 75%, the correction rate is 1%. If 75% ≤ Display SOC < 85%, the correction rate is 2%; if the Display SOC ≥ 85%, the correction rate is 5%.

2. A battery SOC dynamic correction system, characterized in that, include: The judgment module is used to determine the range of the displayed SOC; A correction module, connected to the judgment module, adjusts the correction rate of the displayed SOC by increasing or decreasing the current according to the range of the displayed SOC, so that the displayed SOC is equal to the true SOC; If the displayed SOC is ≤ 35%, the correction rate is 5%; if 35% < displayed SOC ≤ 45%, the correction rate is 2%; if 45% < displayed SOC < 75%, the correction rate is 1%. If 75% ≤ Display SOC < 85%, the correction rate is 2%; if the Display SOC ≥ 85%, the correction rate is 5%.

3. A car, characterized in that, Includes the battery SOC dynamic correction system as described in claim 2.

Images