SOC calibration method and system for solid-state battery of electric vehicle

Abstract

The invention belongs to the technical field of electric vehicles, and particularly relates to an SOC calibration method and system for a solid-state battery of an electric vehicle, and the calibration method comprises the steps: pre-storing the OCV-SOC curve information of the solid-state battery to a calibration module; when the BMS unit is in the wake-up mode, charging current information and discharging current information of the solid-state battery are collected and sent to the judgment module; the judgment module judges that the solid-state battery is in a charging condition, a discharging condition or an unknown condition in each period according to the charging current information and the discharging current information; the judgment result is sent to the calibration module for storage; at the initial moment when the BMS unit enters the wake-up mode, open-circuit voltage information of the solid-state battery is collected and sent to the calibration module, and the calibration module judges whether calibration is needed or not according to judgment results of all periods stored during the previous wake-up mode and selects a calibration curve in pre-stored OCV-SOC curve information when it is judged that calibration is needed; and the calibration module is used for calibrating the SOC of the solid-state battery according to the open-circuit voltage information and the selected calibration curve.

Description

Technical Field

[0001] This invention belongs to the field of electric vehicle technology, specifically relating to a SOC calibration method and system for solid-state batteries in electric vehicles. Background Technology

[0002] State of Charge (SOC) is a key parameter of solid-state batteries in electric vehicles. It measures the battery's remaining energy and serves as an important reference for preventing overcharging and over-discharging, as well as for overall vehicle energy control. SOC is not an external characteristic parameter of solid-state batteries and requires secondary calculation. The main calculation methods include the discharge method, open-circuit voltage method, electrochemical impedance method, ampere-hour integration method, neural network, and Kalman filtering method. The commonly used method in the industry is the ampere-hour integration method, but it suffers from large cumulative errors. Therefore, SOC calibration is necessary. Existing SOC calibration strategies for electric vehicle solid-state batteries typically rely on the standard OCV-SOC curve of the solid-state battery (since the voltage hysteresis effect during charging and discharging is opposite, the standard OCV-SOC curve is usually obtained by averaging the charging OCV-SOC curve and the discharging OCV-SOC curve obtained from charge-discharge tests) and the open-circuit voltage value of the solid-state battery at the initial moment when the BMS unit enters wake-up mode to obtain the calibrated SOC value.

[0003] However, the accuracy of calibrating the SOC of a solid-state battery using the standard OCV-SOC curve is affected by the resting time of the solid-state battery. If the resting time is insufficient, the voltage hysteresis effect during the charging and discharging process will not be completely eliminated. As a result, the actual OCV-SOC curve of the solid-state battery at this time will be closer to the charging OCV-SOC curve or the discharging OCV-SOC curve due to the operating conditions (charging or discharging) before resting. This will lead to errors in the obtained SOC calibration value.

[0004] However, the accuracy of calibrating the SOC of solid-state batteries using existing SOC calibration strategies for electric vehicles is limited by the resting time. This leads to technical problems such as large calibration errors or large errors in the displayed SOC value of solid-state batteries when electric vehicles are used frequently and solid-state batteries cannot be fully rested for long periods of time, depending on the calibration triggering mechanism (different settings for the minimum resting time to trigger calibration). Summary of the Invention

[0005] To address the shortcomings of the prior art, this invention provides a SOC calibration method and system for solid-state batteries in electric vehicles. This solves the technical problem that the accuracy of SOC calibration using existing SOC calibration strategies for electric vehicles is limited by the settling time. Consequently, in scenarios where electric vehicles are used frequently and the solid-state battery cannot be sufficiently rested for extended periods, the existing SOC calibration strategies can lead to significant calibration errors depending on the calibration trigger mechanism (different minimum settling time for triggering calibration), or significant errors in the displayed SOC value due to prolonged periods without triggering calibration.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: A method for SOC calibration of a solid-state battery for electric vehicles, comprising: Obtain the OCV-SOC curve information of the solid-state battery of the electric vehicle, and pre-store the OCV-SOC curve information in the calibration module. The OCV-SOC curve information includes the charging OCV-SOC curve and the discharging OCV-SOC curve of the solid-state battery. When the BMS unit of the electric vehicle is in wake-up mode, the charging current information and discharging current information of the solid-state battery are collected by the current sensor component, and the collected charging current information and discharging current information are sent to the judgment module in real time. When the BMS unit is in wake-up mode, the judgment module determines, based on the charging current information and the discharging current information, whether the solid-state battery is in charging condition, discharging condition or unknown condition in each cycle, with a preset time period as the cycle; and sends the judgment result to the calibration module for storage. At the initial moment when the BMS unit enters the wake-up mode, the open-circuit voltage information of the solid-state battery is collected using a voltage sensor, and the collected open-circuit voltage information is sent to the calibration module. The calibration module determines whether calibration is required based on the judgment results of each cycle stored during the previous wake-up mode of the BMS unit, and selects a curve from the pre-stored OCV-SOC curve information as the calibration curve when calibration is required. The calibration module obtains the SOC calibration value of the solid-state battery based on the selected calibration curve and the received open-circuit voltage information. The calibration module controls the BMS unit to calibrate the SOC of the solid-state battery based on the obtained SOC calibration value.

[0007] The SOC calibration method for solid-state batteries in electric vehicles provided by this invention can utilize the judgment module to determine the operating conditions (charging, discharging, or unknown conditions) of the BMS unit during each cycle of its previous wake-up mode. Based on the judgment results stored during the previous wake-up mode, the calibration module determines whether calibration is needed at the initial moment when the BMS unit enters wake-up mode (in essence, whether it can be identified whether the actual OCV-SOC curve of the solid-state battery is closer to the charging OCV-SOC curve or the discharging OCV-SOC curve; if it can be identified, calibration is required; otherwise, calibration is not required). After determining that calibration is needed, a curve that is closer to the actual OCV-SOC curve of the solid-state battery at this time is selected from the pre-stored OCV-SOC curve information. The closest curve is used as the calibration curve (that is, to further determine whether the actual OCV-SOC curve of the solid-state battery is closer to the charging OCV-SOC curve or the discharging OCV-SOC curve, and select the charging OCV-SOC curve or the discharging OCV-SOC curve as the calibration curve according to the determination result); In scenarios where electric vehicles are used frequently and solid-state batteries cannot be fully rested for a long time, compared with the existing SOC calibration method for electric vehicle solid-state batteries that uses the standard OCV-SOC curve as the calibration curve, the SOC calibration value obtained by the SOC calibration method for electric vehicle solid-state batteries provided by this invention is more accurate, and can reduce the impact of resting time on calibration accuracy. It can accurately calibrate the SOC of solid-state batteries in scenarios where electric vehicles are used frequently and solid-state batteries cannot be fully rested for a long time, and maintain the accuracy of the SOC display value of solid-state batteries.

[0008] The calibration module's method for determining whether calibration is needed (i.e., whether it can identify whether the actual OCV-SOC curve of the solid-state battery is closer to the charging OCV-SOC curve or the discharging OCV-SOC curve) can have various technical solutions, including but not limited to: In one of the technical solutions, the method by which the calibration module determines whether calibration is required includes: If the solid-state battery was in charging or discharging mode during the last cycle of the previous wake-up mode of the BMS unit, the calibration module determines that calibration is required. If the solid-state battery was in an unknown operating condition during the last cycle of the previous wake-up mode of the BMS unit, the calibration module determines that no calibration is required.

[0009] In another technical solution, the method by which the calibration module determines whether calibration is required includes: If the solid-state battery was in an unknown operating condition for the last two cycles during the previous wake-up mode of the BMS unit, the calibration module determines that no calibration is required. If the solid-state battery is in charging or discharging mode in either of the last two cycles during the previous wake-up period of the BMS unit, the calibration module determines that calibration is required.

[0010] Furthermore, at the initial moment when the BMS unit enters the wake-up mode, the BMS unit sends the sleep duration information before entering the wake-up mode to the calibration module. The calibration module determines whether calibration is required based on the judgment results of each cycle stored during the previous wake-up mode of the BMS unit, combined with the received sleep duration information, and selects a curve from the pre-stored OCV-SOC curve information as the calibration curve when it determines that calibration is required.

[0011] By utilizing the triggering mechanism of the BMS unit, which typically enters sleep mode after the solid-state battery has been idle for the designed duration, and combining this sleep duration information to determine whether calibration is needed (i.e., whether it can be identified whether the actual OCV-SOC curve of the solid-state battery is closer to the charging OCV-SOC curve or the discharging OCV-SOC curve), it is possible to effectively avoid situations where the SOC of the solid-state battery is calibrated before the actual OCV-SOC curve of the solid-state battery has approached the charging OCV-SOC curve or the discharging OCV-SOC curve due to the short idle time of the solid-state battery and the open-circuit voltage still being in the initial unstable period after idle time, resulting in a large calibration error.

[0012] Furthermore, the method by which the calibration module determines whether calibration is required includes: If the sleep duration of the BMS unit before entering the wake-up mode is less than the first preset duration, the calibration module determines that no calibration is required. If the sleep duration of the BMS unit before entering the wake-up mode is not less than the first preset duration, and the last two cycles of the BMS unit during the previous wake-up mode were in unknown working conditions, then the calibration module determines that no calibration is required. If the sleep duration of the BMS unit before entering the wake-up mode is not less than the first preset duration, and the BMS unit was in charging or discharging mode in either of the last two cycles during the previous wake-up mode, then the calibration module determines that calibration is required.

[0013] Furthermore, the first preset duration ranges from half an hour to two hours.

[0014] In one of the technical solutions, the OCV-SOC curve information includes only the charging OCV-SOC curve and the discharging OCV-SOC curve.

[0015] Correspondingly, the method for selecting the calibration curve includes: If the solid-state battery is in charging condition during the last cycle of the previous wake-up mode of the BMS unit, or if the solid-state battery is in unknown condition during the last cycle of the previous wake-up mode of the BMS unit, but is in charging condition during the penultimate cycle, then the calibration module selects the charging OCV-SOC curve as the calibration curve. If the solid-state battery is in a discharge condition during the last cycle of the previous wake-up mode of the BMS unit, or if the solid-state battery is in an unknown condition during the last cycle of the previous wake-up mode of the BMS unit, but is in a discharge condition during the penultimate cycle, then the calibration module selects the discharge OCV-SOC curve as the calibration curve.

[0016] In another technical solution, the OCV-SOC curve information also includes the standard OCV-SOC curve of the solid-state battery.

[0017] Correspondingly, the method for selecting the calibration curve includes: If the sleep duration of the BMS unit before entering the wake-up mode is not less than the first preset duration but less than the second preset duration, and the solid-state battery was in charging mode during the last cycle of the previous wake-up mode of the BMS unit; then the calibration module selects the charging OCV-SOC curve as the calibration curve. If the sleep duration of the BMS unit before entering the wake-up mode is not less than the first preset duration but less than the second preset duration, and the solid-state battery was in an unknown condition during the last cycle of the previous wake-up mode of the BMS unit, but in a charging condition during the penultimate cycle, then the calibration module selects the charging OCV-SOC curve as the calibration curve. If the sleep duration of the BMS unit before entering the wake-up mode is not less than the first preset duration but less than the second preset duration, and the solid-state battery is in the discharge condition during the last cycle of the previous wake-up mode of the BMS unit; then the calibration module selects the discharge OCV-SOC curve as the calibration curve. If the sleep duration of the BMS unit before entering the wake-up mode is not less than the first preset duration but less than the second preset duration, and the solid-state battery was in an unknown operating condition during the last cycle of the previous wake-up mode of the BMS unit, but in a discharge operating condition during the penultimate cycle, then the calibration module selects the discharge OCV-SOC curve as the calibration curve. If the sleep duration of the BMS unit before entering the wake-up mode is not less than the second preset duration, then the calibration module selects the standard OCV-SOC curve as the calibration curve.

[0018] By utilizing the BMS unit's trigger mechanism, which typically initiates a sleep mode after the solid-state battery has been in a resting state for the designed duration, and by combining this sleep duration information, it can be determined whether calibration is needed (i.e., whether it can be identified whether the actual OCV-SOC curve of the solid-state battery at this time is closer to the charging OCV-SOC curve, the discharging OCV-SOC curve, or the standard OCV-SOC curve). This effectively avoids situations where the solid-state battery's open-circuit voltage is still in the initial unstable period after resting due to an insufficient resting time, and the actual OCV-SOC curve of the solid-state battery has not yet approached the charging OCV-SOC curve or the discharging OCV-SOC curve. The method addresses the issue of significant calibration errors during SOC calibration of the solid-state battery. Furthermore, it addresses the problem of selecting the standard OCV-SOC curve as the calibration curve to obtain the SOC calibration value when the solid-state battery has been left to rest for a sufficient period (i.e., the sleep time before the BMS unit enters wake-up mode is not less than a second preset time) and the actual OCV-SOC curve of the solid-state battery is close to the standard OCV-SOC curve. This allows the SOC calibration method for electric vehicle solid-state batteries provided by this invention to be applicable not only to scenarios where electric vehicles have high usage frequency and the solid-state battery cannot be left to rest for extended periods, but also to scenarios where the solid-state battery can be left to rest.

[0019] Furthermore, when the BMS unit is in wake-up mode, the judgment module calculates the change in charge of the solid-state battery in each cycle based on the charging current information and the discharging current information, with a preset duration as the cycle, and makes a judgment based on the obtained change in charge information. If the change in charge of the solid-state battery in any cycle is greater than the first preset charge value, the determination module determines that the solid-state battery is in charging mode in that cycle. If the change in charge of the solid-state battery in any cycle is less than the second preset charge value, the determination module determines that the solid-state battery is in a discharge state in that cycle. If the change in charge of the solid-state battery in any cycle is not greater than the first preset charge value and not less than the second preset charge value, then the determination module determines that the solid-state battery is in an unknown operating condition in that cycle.

[0020] Based on the SOC calibration method for solid-state batteries of electric vehicles provided by the present invention, the present invention also provides an SOC calibration system for solid-state batteries of electric vehicles, including a calibration module, a judgment module and a BMS unit disposed on the electric vehicle, and a current sensor assembly and a voltage sensor assembly disposed on the solid-state battery of the electric vehicle. The SOC calibration system for the solid-state battery of the electric vehicle is used to perform the SOC calibration method for the solid-state battery of the electric vehicle provided by the present invention. Attached Figure Description

[0021] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a flowchart illustrating the SOC calibration method for solid-state batteries in electric vehicles in Example 1. Figure 2 This is a flowchart illustrating the SOC calibration method for solid-state batteries in electric vehicles in Example 2. Figure 3 This is a flowchart illustrating the SOC calibration method for solid-state batteries in electric vehicles in Example 3. Detailed Implementation

[0023] 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 embodiments of the present invention, and not all embodiments.

[0024] Example 1: As Figure 1 As shown, this embodiment 1 provides a SOC calibration method for solid-state batteries in electric vehicles, including: Obtain the OCV-SOC curve information of the solid-state battery of the electric vehicle and pre-store the OCV-SOC curve information to the calibration module. The OCV-SOC curve information includes the charging OCV-SOC curve and the discharging OCV-SOC curve of the solid-state battery. When the BMS unit of an electric vehicle is in wake-up mode, the current sensor component is used to collect the charging current information and discharging current information of the solid battery, and the collected charging current information and discharging current information are sent to the judgment module in real time. When the BMS unit is in wake-up mode, the judgment module determines whether the solid-state battery is in charging condition, discharging condition or unknown condition in each cycle based on the charging current information and discharging current information, with a preset time period as the cycle; and sends the judgment result to the calibration module for storage. At the initial moment when the BMS unit enters the wake-up mode, the open-circuit voltage information of the solid-state battery is collected using a voltage sensor, and the collected open-circuit voltage information is sent to the calibration module. The calibration module determines whether calibration is required based on the judgment results of each cycle stored during the previous wake-up mode of the BMS unit, and selects a curve from the pre-stored OCV-SOC curve information as the calibration curve when calibration is required. The calibration module obtains the SOC calibration value of the solid-state battery based on the selected calibration curve and the received open-circuit voltage information. The calibration module controls the BMS unit to calibrate the SOC of the solid-state battery based on the obtained SOC calibration value.

[0025] The SOC calibration method for solid-state batteries in electric vehicles provided by this invention can utilize a judgment module to determine the operating conditions (charging, discharging, or unknown conditions) of the BMS unit during each cycle of its previous wake-up mode. Based on the judgment results stored during the previous wake-up mode, the calibration module determines whether calibration is needed at the initial moment when the BMS unit enters wake-up mode (essentially, determining whether the actual OCV-SOC curve of the solid-state battery is closer to the charging OCV-SOC curve or the discharging OCV-SOC curve; if it can be identified, calibration is required; otherwise, it is not required). After determining that calibration is needed, a curve that is closer to the actual OCV-SOC curve of the solid-state battery at this time is selected from the pre-stored OCV-SOC curve information. To calibrate the curve (i.e., to further determine whether the actual OCV-SOC curve of the solid-state battery is closer to the charging OCV-SOC curve or the discharging OCV-SOC curve, and select the charging OCV-SOC curve or the discharging OCV-SOC curve as the calibration curve based on the determination result); in scenarios where electric vehicles are used frequently and solid-state batteries cannot be fully rested for a long time, compared with the existing calibration strategy of using the standard OCV-SOC curve as the calibration curve for SOC calibration of electric vehicle solid-state batteries, the SOC calibration value obtained by the SOC calibration method of electric vehicle solid-state batteries provided by this invention is more accurate, and can reduce the impact of resting time on calibration accuracy. It can accurately calibrate the SOC of solid-state batteries in scenarios where electric vehicles are used frequently and solid-state batteries cannot be fully rested for a long time, and maintain the accuracy of the SOC display value of solid-state batteries.

[0026] The charging OCV-SOC curve and the discharging OCV-SOC curve can be obtained by calibrating the solid-state battery through charging and discharging tests. The specific calibration method is common knowledge in the field, so it will not be described in detail in this invention.

[0027] In this embodiment 1, there are various technical solutions for the calibration module to determine whether calibration is needed (i.e., whether it can identify whether the actual OCV-SOC curve of the solid-state battery is closer to the charging OCV-SOC curve or the discharging OCV-SOC curve). These solutions include, but are not limited to: Option 1: The calibration module determines whether calibration is needed using the following methods: If the solid-state battery is in charging or discharging mode during the last cycle of the previous wake-up mode of the BMS cell, the calibration module determines that calibration is required. If the solid-state battery is in an unknown operating condition during the last cycle of the previous wake-up mode of the BMS cell, the calibration module determines that no calibration is required.

[0028] Option 2: The calibration module determines whether calibration is needed using the following methods: If the solid-state battery is in an unknown operating condition for the last two cycles during the previous wake-up mode of the BMS cell, the calibration module determines that no calibration is required. If the solid-state battery is in charging or discharging mode in either of the last two cycles during the previous wake-up period of the BMS cell, the calibration module determines that calibration is required.

[0029] In this embodiment 1, the method for selecting the calibration curve includes: If the solid-state battery is in charging condition during the last cycle of the previous wake-up mode of the BMS unit, or if the solid-state battery is in unknown condition during the last cycle of the previous wake-up mode of the BMS unit, but is in charging condition during the penultimate cycle, then the calibration module selects the charging OCV-SOC curve as the calibration curve. If the solid-state battery is in a discharge condition during the last cycle of the previous wake-up mode of the BMS cell, or if the solid-state battery is in an unknown condition during the last cycle of the previous wake-up mode of the BMS cell, but is in a discharge condition during the penultimate cycle, then the calibration module selects the discharge OCV-SOC curve as the calibration curve.

[0030] Specifically, in this embodiment 1, when the BMS unit is in wake-up mode, the judgment module calculates the change in the solid battery charge in each cycle based on the charging current information and the discharging current information, with a preset duration as the cycle, and makes a judgment based on the obtained charge change information. If the change in charge of the solid-state battery in any cycle is greater than the first preset charge value, the determination module determines that the solid-state battery is in charging mode in that cycle. If the change in charge of the solid-state battery in any cycle is less than the second preset charge value, the determination module determines that the solid-state battery is in a discharge state in that cycle. If the change in charge of the solid-state battery in any cycle is not greater than the first preset charge value and not less than the second preset charge value, then the determination module determines that the solid-state battery is in an unknown operating condition in that cycle.

[0031] Example 2: Based on the SOC calibration method for solid-state batteries in electric vehicles provided in Example 1, Example 2 also provides a SOC calibration method for solid-state batteries in electric vehicles. The SOC calibration method for solid-state batteries in electric vehicles provided in Example 2 is similar to the SOC calibration method for solid-state batteries in electric vehicles provided in Example 1, except that: In this embodiment 2, as Figure 2 As shown, at the initial moment when the BMS unit enters the wake-up mode, the BMS unit sends the sleep duration information before entering the wake-up mode to the calibration module. The calibration module determines whether calibration is needed based on the judgment results of each cycle stored during the previous wake-up mode of the BMS unit, combined with the received sleep duration information, and selects a curve from the pre-stored OCV-SOC curve information as the calibration curve when it determines that calibration is needed.

[0032] By utilizing the triggering mechanism of the BMS unit, which typically enters sleep mode after the solid-state battery has been in a resting state for the designed duration, and combining this sleep duration information, it can be determined whether calibration is needed (i.e., whether it can be identified whether the actual OCV-SOC curve of the solid-state battery is closer to the charging OCV-SOC curve or the discharging OCV-SOC curve). This effectively avoids situations where the SOC of the solid-state battery is calibrated before the actual OCV-SOC curve of the solid-state battery has approached the charging OCV-SOC curve or the discharging OCV-SOC curve due to the short resting time of the solid-state battery and the open-circuit voltage still being in the initial unstable period after resting, resulting in a large calibration error.

[0033] Correspondingly, in this embodiment 2, the method by which the calibration module determines whether calibration is required includes: If the sleep duration of the BMS unit before entering the wake-up mode is less than the first preset duration, the calibration module determines that no calibration is required. If the sleep duration before the BMS unit enters the wake-up mode this time is not less than the first preset duration, and the last two cycles of the BMS unit during the previous wake-up mode were in unknown working conditions, then the calibration module determines that no calibration is required. If the sleep duration of the BMS unit before entering the wake-up mode is not less than the first preset duration, and the BMS unit was in charging or discharging mode in either of the last two cycles during the previous wake-up mode, then the calibration module determines that calibration is required.

[0034] Preferably, in this embodiment 2, the value range of the first preset duration is from half an hour to two hours.

[0035] In this embodiment 2, the method for selecting the calibration curve includes: If the solid-state battery is in charging condition during the last cycle of the previous wake-up mode of the BMS unit, or if the solid-state battery is in unknown condition during the last cycle of the previous wake-up mode of the BMS unit, but is in charging condition during the penultimate cycle, then the calibration module selects the charging OCV-SOC curve as the calibration curve. If the solid-state battery is in a discharge condition during the last cycle of the previous wake-up mode of the BMS cell, or if the solid-state battery is in an unknown condition during the last cycle of the previous wake-up mode of the BMS cell, but is in a discharge condition during the penultimate cycle, then the calibration module selects the discharge OCV-SOC curve as the calibration curve.

[0036] Example 3: Based on the SOC calibration method for solid-state batteries in electric vehicles provided in Example 2, Example 3 also provides an SOC calibration method for solid-state batteries in electric vehicles. The SOC calibration method for solid-state batteries in electric vehicles provided in Example 3 is an improved scheme based on the SOC calibration method for solid-state batteries in electric vehicles provided in Example 2. The difference is: In this embodiment 3, as Figure 3 As shown, the OCV-SOC curve information also includes the standard OCV-SOC curve for solid-state batteries.

[0037] Correspondingly, in this embodiment 3, the method for selecting the calibration curve includes: If the sleep duration before the BMS unit enters the wake-up mode this time is not less than the first preset duration but less than the second preset duration, and the solid-state battery is in the charging state during the last cycle of the previous wake-up mode of the BMS unit; then the calibration module selects the charging OCV-SOC curve as the calibration curve. If the sleep duration of the BMS unit before entering the wake-up mode is not less than the first preset duration but less than the second preset duration, and the solid-state battery is in an unknown condition in the last cycle during the previous wake-up mode of the BMS unit, but in a charging condition in the second to last cycle, then the calibration module selects the charging OCV-SOC curve as the calibration curve. If the sleep duration before the BMS unit enters the wake-up mode this time is not less than the first preset duration but less than the second preset duration, and the solid-state battery is in the discharge condition during the last cycle of the previous wake-up mode of the BMS unit; then the calibration module selects the discharge OCV-SOC curve as the calibration curve. If the sleep duration before the BMS unit enters the wake-up mode this time is not less than the first preset duration but less than the second preset duration, and the solid-state battery is in an unknown condition in the last cycle during the previous wake-up mode of the BMS unit, but in a discharge condition in the second to last cycle, then the calibration module selects the discharge OCV-SOC curve as the calibration curve. If the sleep duration of the BMS unit before entering the wake-up mode is not less than the second preset duration, the calibration module selects the standard OCV-SOC curve as the calibration curve.

[0038] By utilizing the BMS unit's trigger mechanism that typically initiates sleep mode after the solid-state battery has reached its designed resting time, and combining this sleep time information, it's possible to determine whether calibration is needed (i.e., whether it can identify whether the actual OCV-SOC curve of the solid-state battery is closer to the charging OCV-SOC curve, the discharging OCV-SOC curve, or the standard OCV-SOC curve). This effectively avoids calibration when the solid-state battery's open-circuit voltage is still in the initial unstable period after resting due to an insufficient resting time, and the actual OCV-SOC curve has not yet approached the charging or discharging OCV-SOC curve. The SOC of the solid-state battery has been calibrated, but a large calibration error has occurred. Furthermore, when the solid-state battery has been left to rest for a sufficient period (i.e., the sleep time before the BMS unit enters wake-up mode is not less than the second preset time), and the actual OCV-SOC curve of the solid-state battery is close to the standard OCV-SOC curve, the calibration module can select the standard OCV-SOC curve as the calibration curve to obtain the SOC calibration value. This makes the SOC calibration method for solid-state batteries in electric vehicles provided by this invention applicable not only to scenarios where electric vehicles have high usage frequency and solid-state batteries cannot be left to rest for extended periods, but also to scenarios where solid-state batteries can be left to rest.

[0039] Example 4: Example 4 provides a SOC calibration system for a solid-state battery in an electric vehicle; including a calibration module, a judgment module and a BMS unit installed on the electric vehicle, and a current sensor assembly and a voltage sensor assembly installed on the solid-state battery in the electric vehicle; The SOC calibration system for solid-state batteries in electric vehicles provided in Example 4 is used to perform the SOC calibration method for solid-state batteries in electric vehicles provided in Example 1, Example 2, or Example 3.

[0040] The SOC calibration method and system for solid-state batteries in electric vehicles provided by this invention have at least the following technical effects or advantages: 1. The SOC calibration method for solid-state batteries in electric vehicles provided by this invention can utilize a judgment module to determine the operating conditions (charging, discharging, or unknown conditions) of each cycle during the previous wake-up mode of the BMS unit. Based on the judgment results stored during the previous wake-up mode, the calibration module determines whether calibration is needed at the initial moment when the BMS unit enters wake-up mode (in essence, determining whether the actual OCV-SOC curve of the solid-state battery is closer to the charging OCV-SOC curve or the discharging OCV-SOC curve; if it can be identified, calibration is required; otherwise, calibration is not required). After determining that calibration is needed, a curve that is closer to the actual OCV-SOC curve of the solid-state battery at this time is selected from the pre-stored OCV-SOC curve information. As a calibration curve (that is, to further determine whether the actual OCV-SOC curve of the solid-state battery is closer to the charging OCV-SOC curve or the discharging OCV-SOC curve, and select the charging OCV-SOC curve or the discharging OCV-SOC curve as the calibration curve according to the judgment result); in scenarios where electric vehicles are used frequently and solid-state batteries cannot be fully rested for a long time, compared with the existing SOC calibration method for electric vehicle solid-state batteries that uses the standard OCV-SOC curve as the calibration curve, the SOC calibration value obtained by the SOC calibration method for electric vehicle solid-state batteries provided by this invention is more accurate, and can reduce the impact of resting time on calibration accuracy. It can accurately calibrate the SOC of solid-state batteries in scenarios where electric vehicles are used frequently and solid-state batteries cannot be fully rested for a long time, and maintain the accuracy of the SOC display value of solid-state batteries.

[0041] 2. Utilizing the BMS unit's trigger mechanism that typically enters sleep mode after the solid-state battery has been idle for the designed duration, and by combining the sleep duration information, it can determine whether calibration is needed (i.e., whether it can identify whether the actual OCV-SOC curve of the solid-state battery is closer to the charging OCV-SOC curve or the discharging OCV-SOC curve). This effectively avoids situations where the SOC of the solid-state battery is calibrated before the actual OCV-SOC curve of the solid-state battery has approached the charging or discharging OCV-SOC curve due to the insufficient idle time of the solid-state battery and the open-circuit voltage still being in the initial unstable period after idle time, resulting in a large calibration error.

[0042] 3. Utilizing the BMS unit's trigger mechanism that typically initiates sleep mode after the solid-state battery has reached its designed resting time, and by combining this sleep time information, it determines whether calibration is needed (i.e., whether it can identify whether the actual OCV-SOC curve of the solid-state battery is closer to the charging OCV-SOC curve, the discharging OCV-SOC curve, or the standard OCV-SOC curve). This effectively avoids situations where the solid-state battery's resting time is too short, the open-circuit voltage is still in the initial unstable period after resting, and the actual OCV-SOC curve of the solid-state battery has not yet approached the charging or discharging OCV-SOC curve, before calibration is performed. The SOC calibration of the solid-state battery has resulted in a significant calibration error. Furthermore, when the solid-state battery has been left to rest for a sufficient period (i.e., the sleep time before the BMS unit enters wake-up mode is not less than a second preset time), and the actual OCV-SOC curve of the solid-state battery is close to the standard OCV-SOC curve, the calibration module can select the standard OCV-SOC curve as the calibration curve to obtain the SOC calibration value. This allows the SOC calibration method for electric vehicle solid-state batteries provided by this invention to be applicable not only to scenarios where electric vehicles have high usage frequency and the solid-state battery cannot be left to rest for extended periods, but also to scenarios where the solid-state battery can be left to rest.

[0043] The above are merely specific application examples of the present invention and do not constitute any limitation on the scope of protection of the present invention. All technical solutions formed by equivalent transformation or equivalent substitution fall within the scope of protection of the present invention.

Claims

1. A method for SOC calibration of a solid-state battery for electric vehicles, characterized in that, include: Obtain the OCV-SOC curve information of the solid-state battery of the electric vehicle, and pre-store the OCV-SOC curve information in the calibration module. The OCV-SOC curve information includes the charging OCV-SOC curve and the discharging OCV-SOC curve of the solid-state battery. When the BMS unit of the electric vehicle is in wake-up mode, the charging current information and discharging current information of the solid-state battery are collected by the current sensor component, and the collected charging current information and discharging current information are sent to the judgment module in real time. When the BMS unit is in wake-up mode, the judgment module determines, based on the charging current information and the discharging current information, whether the solid-state battery is in charging condition, discharging condition or unknown condition in each cycle, with a preset time period as the cycle. The judgment result is then sent to the calibration module for storage. At the initial moment when the BMS unit enters the wake-up mode, the open-circuit voltage information of the solid-state battery is collected using a voltage sensor, and the collected open-circuit voltage information is sent to the calibration module. The calibration module determines whether calibration is required based on the judgment results of each cycle stored during the previous wake-up mode of the BMS unit, and selects a curve from the pre-stored OCV-SOC curve information as the calibration curve when it is determined that calibration is required. The calibration module obtains the SOC calibration value of the solid-state battery based on the selected calibration curve and the received open-circuit voltage information; the calibration module controls the BMS unit to calibrate the SOC of the solid-state battery based on the obtained SOC calibration value.

2. The SOC calibration method for solid-state batteries in electric vehicles according to claim 1, characterized in that, The calibration module determines whether calibration is required by the following methods: If the solid-state battery was in charging or discharging mode during the last cycle of the previous wake-up mode of the BMS unit, the calibration module determines that calibration is required. If the solid-state battery was in an unknown operating condition during the last cycle of the previous wake-up mode of the BMS unit, the calibration module determines that no calibration is required.

3. The SOC calibration method for solid-state batteries in electric vehicles according to claim 1, characterized in that, The calibration module determines whether calibration is required by the following methods: If the solid-state battery was in an unknown operating condition for the last two cycles during the previous wake-up mode of the BMS unit, the calibration module determines that no calibration is required. If the solid-state battery is in charging or discharging mode in either of the last two cycles during the previous wake-up period of the BMS unit, the calibration module determines that calibration is required.

4. The SOC calibration method for solid-state batteries in electric vehicles according to claim 1, characterized in that: At the initial moment when the BMS unit enters the wake-up mode, the BMS unit sends the sleep duration information before entering the wake-up mode to the calibration module; The calibration module determines whether calibration is required based on the judgment results of each cycle stored during the previous wake-up mode of the BMS unit, combined with the received sleep duration information, and selects a curve from the pre-stored OCV-SOC curve information as the calibration curve when it determines that calibration is required.

5. The SOC calibration method for solid-state batteries in electric vehicles according to claim 4, characterized in that, The calibration module determines whether calibration is required by the following methods: If the sleep duration of the BMS unit before entering the wake-up mode is less than the first preset duration, the calibration module determines that no calibration is required. If the sleep duration of the BMS unit before entering the wake-up mode is not less than the first preset duration, and the last two cycles of the BMS unit during the previous wake-up mode were in unknown working conditions, then the calibration module determines that no calibration is required. If the sleep duration of the BMS unit before entering the wake-up mode is not less than the first preset duration, and the BMS unit was in charging or discharging mode in either of the last two cycles during the previous wake-up mode, then the calibration module determines that calibration is required.

6. The SOC calibration method for solid-state batteries in electric vehicles according to claim 5, characterized in that, The method for selecting the calibration curve includes: If the solid-state battery is in charging condition during the last cycle of the previous wake-up mode of the BMS unit, or if the solid-state battery is in unknown condition during the last cycle of the previous wake-up mode of the BMS unit, but is in charging condition during the penultimate cycle, then the calibration module selects the charging OCV-SOC curve as the calibration curve. If the solid-state battery is in a discharge condition during the last cycle of the previous wake-up mode of the BMS unit, or if the solid-state battery is in an unknown condition during the last cycle of the previous wake-up mode of the BMS unit, but is in a discharge condition during the penultimate cycle, then the calibration module selects the discharge OCV-SOC curve as the calibration curve.

7. The SOC calibration method for solid-state batteries in electric vehicles according to claim 5, characterized in that: The OCV-SOC curve information also includes the standard OCV-SOC curve of the solid-state battery.

8. The SOC calibration method for solid-state batteries in electric vehicles according to claim 7, characterized in that: The method for selecting the calibration curve includes: If the sleep duration of the BMS unit before entering the wake-up mode is not less than the first preset duration but less than the second preset duration, and the solid-state battery was in charging mode during the last cycle of the previous wake-up mode of the BMS unit; then the calibration module selects the charging OCV-SOC curve as the calibration curve. If the sleep duration of the BMS unit before entering the wake-up mode is not less than the first preset duration but less than the second preset duration, and the solid-state battery was in an unknown condition during the last cycle of the previous wake-up mode of the BMS unit, but in a charging condition during the penultimate cycle, then the calibration module selects the charging OCV-SOC curve as the calibration curve. If the sleep duration of the BMS unit before entering the wake-up mode is not less than the first preset duration but less than the second preset duration, and the solid-state battery is in the discharge condition during the last cycle of the previous wake-up mode of the BMS unit; then the calibration module selects the discharge OCV-SOC curve as the calibration curve. If the sleep duration of the BMS unit before entering the wake-up mode is not less than the first preset duration but less than the second preset duration, and the solid-state battery was in an unknown operating condition during the last cycle of the previous wake-up mode of the BMS unit, but in a discharge operating condition during the penultimate cycle, then the calibration module selects the discharge OCV-SOC curve as the calibration curve. If the sleep duration of the BMS unit before entering the wake-up mode is not less than the second preset duration, then the calibration module selects the standard OCV-SOC curve as the calibration curve.

9. The SOC calibration method for solid-state batteries in electric vehicles according to claim 1, characterized in that: When the BMS unit is in wake-up mode, the judgment module calculates the change in charge of the solid-state battery in each cycle based on the charging current information and the discharging current information, with a preset duration as the cycle, and makes a judgment based on the obtained change in charge information. If the change in charge of the solid-state battery in any cycle is greater than the first preset charge value, the determination module determines that the solid-state battery is in charging mode in that cycle. If the change in charge of the solid-state battery in any cycle is less than the second preset charge value, the determination module determines that the solid-state battery is in a discharge state in that cycle. If the change in charge of the solid-state battery in any cycle is not greater than the first preset charge value and not less than the second preset charge value, then the determination module determines that the solid-state battery is in an unknown operating condition in that cycle.

10. A SOC calibration system for a solid-state battery in an electric vehicle, characterized in that: It includes a calibration module, a judgment module, and a BMS unit installed on the electric vehicle, as well as a current sensor assembly and a voltage sensor assembly installed on the solid-state battery of the electric vehicle; The SOC calibration system for the solid-state battery of the electric vehicle is used to perform the SOC calibration method for the solid-state battery of the electric vehicle as described in any one of claims 1-9.

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