Method, device, vehicle and storage medium for precharging vehicle power battery

Abstract

The present application provides a method, device, vehicle, and storage medium for precharging a vehicle power battery. The method is applicable to the field of vehicle charging and includes: obtaining the precharging duration and operating parameters of the power battery pack when the power battery is in the precharging stage, where the battery pack operating parameters are used to indicate the operating state of the power battery pack; determining a target precharging voltage based on the precharging duration and the battery pack operating parameters; and transmitting the target precharging voltage to a charging station so that the charging station charges the power battery at the target precharging voltage. This method can flexibly adjust the precharging voltage in real time during the power battery precharging process, thereby improving the precharging success rate of the power battery.

Description

Technical Field

[0001] The present application relates to the field of vehicle charging, and more specifically, to a method, device, vehicle, and storage medium for pre-charging a vehicle power battery in the field of vehicle charging. Background Art

[0002] Currently, new energy vehicles can use electric motors as a driving source. During the vehicle's operation, if the power battery is low on power, the user needs to drive the vehicle to a charging station in time to recharge the power battery.

[0003] Before charging the power battery, the charging station generally performs a pre-charge. This prevents the power battery from being subjected to a high current surge when the power battery voltage is low and the charging station output voltage is high, which could damage the vehicle's battery management system (BMS).

[0004] In the related art, when pre-charging a power battery, the pre-charging voltage is usually controlled to be always a fixed value, resulting in that the pre-charging voltage cannot be adjusted according to the actual situation during the pre-charging process of the power battery, which easily leads to pre-charging failure. Summary of the Invention

[0005] The present application provides a method, device, vehicle and storage medium for pre-charging a vehicle power battery. The method can flexibly adjust the pre-charging voltage in real time during the power battery pre-charging process, thereby improving the pre-charging success rate of the power battery.

[0006] In a first aspect, a method for pre-charging a vehicle power battery is provided, the method comprising: when the power battery is in a pre-charging stage, obtaining the pre-charging time of the power battery and the operating parameters of the battery pack of the power battery, the battery pack operating parameters being used to indicate the operating state of the battery pack of the power battery; determining a target pre-charging voltage based on the pre-charging time and the operating parameters of the battery pack, the difference between the target pre-charging voltage and the actual voltage of the battery pack being less than or equal to a first voltage difference; and sending the target pre-charging voltage to a charging pile so that the charging pile charges the power battery at the target pre-charging voltage.

[0007] In the above technical solution, during the charging process of the vehicle power battery, this application proposes a method for pre-charging the vehicle power battery, in which the vehicle can obtain the pre-charging time of the power battery and the operating parameters of the battery pack during the pre-charging process, and dynamically adjust the target pre-charging voltage of the power battery according to the pre-charging time and the operating parameters of the battery pack. In the above process, the pre-charging voltage of the battery pack can be flexibly determined according to the actual operating conditions of the battery pack, so that the pre-charging voltage matches the current operating environment of the battery pack. Finally, the vehicle sends the target pre-charging voltage to the charging pile, which enables the charging pile to reasonably output the corresponding pre-charging voltage according to the current needs of the power battery, thereby reducing the voltage difference between the actual voltage of the battery pack and the output voltage of the charging pile, and improving the charging efficiency and success rate of the power battery.

[0008] In combination with the first aspect, in some possible implementations, the battery pack operating parameters include the actual battery pack voltage and the battery pack temperature. The target pre-charge voltage is determined based on the pre-charge time and the battery pack operating parameters, including: determining the predicted pre-charge voltage based on the pre-charge time and the actual battery pack voltage; determining the target pre-charge voltage based on the predicted pre-charge voltage and the battery pack temperature.

[0009] In combination with the first aspect and the above-mentioned implementation methods, in some possible implementation methods, the predicted pre-charge voltage is determined based on the pre-charge time and the actual voltage of the battery pack, including: when the pre-charge time is less than or equal to the first preset time, determining the predicted pre-charge voltage as the actual voltage of the battery pack; when the pre-charge time is greater than the first preset time and less than or equal to the second preset time, determining the target voltage difference between the actual voltage of the battery pack and the second voltage difference; determining the predicted pre-charge voltage as the voltage with the smaller value between the target voltage difference and the maximum voltage limit of the charging pile; when the pre-charge time is greater than the second preset time and less than or equal to the third preset time, determining the predicted pre-charge voltage as the voltage with the smaller value between the actual voltage of the battery pack and the maximum voltage limit of the charging pile.

[0010] In the above technical solution, specifically, during the power battery charging process, if the current pre-charge duration is less than or equal to the first preset duration, it means that the current power battery is in the initial pre-charge stage. In this stage, the predicted pre-charge voltage is controlled to be the actual voltage of the battery pack, ensuring that no voltage difference is generated in the initial pre-charge stage, thereby avoiding the risk of current shock and arc generation in the power battery. When the pre-charge duration is greater than the first preset duration and less than the second preset duration, by calculating the target voltage difference and selecting the smaller voltage as the predicted pre-charge voltage, the difference between the output voltage of the charging pile and the actual voltage of the battery pack can also be reduced. When the pre-charge duration is greater than the second preset duration but less than the third preset duration, the predicted pre-charge voltage is the smaller voltage between the actual voltage of the battery pack and the maximum voltage limit of the charging pile, ensuring that the pre-charge voltage can be close to the actual voltage of the battery pack and completing the pre-charge process. Therefore, the above process can dynamically adjust the pre-charge voltage at each stage of the pre-charge process to ensure that the voltage difference between the pre-charge voltage (or the output voltage of the charging pile) and the actual voltage of the battery pack can be controlled within a reasonable range, thereby improving the pre-charge success rate of the power battery.

[0011] In combination with the first aspect and the above-mentioned implementation methods, in some possible implementation methods, the step of determining the second voltage difference includes: when the pre-charging time is equal to the first preset time, determining the third voltage difference between the output voltage of the charging pile and the actual voltage of the battery pack; according to the identification of the power battery and the identification of the charging pile, looking up the table to determine the fourth voltage difference; determining the preset voltage difference as the sum of the third voltage difference and the fourth voltage difference.

[0012] In the above technical solution, since during the power battery charging process, when the voltage is transmitted from the charging pile to the power battery end, a voltage drop will occur due to the wiring harness and other factors, resulting in the output voltage of the charging pile not being equal to the voltage reaching the battery pack. Therefore, in order to avoid this situation where the difference between the actual voltage of the battery pack and the output voltage of the charging pile becomes larger and larger, resulting in inaccurate pre-charge voltage, the vehicle can record the voltage difference between the output voltage of the charging pile and the actual voltage of the battery pack during the pre-charge process, so as to facilitate timely adjustment during the pre-charge process. In addition, due to the influence of the battery pack brand and the charging pile brand, there will also be an error between the output voltage of the charging pile and the actual voltage of the battery pack. Therefore, when determining the pre-charge voltage, the embodiment of the present application takes into account the combined influence of the two voltage errors, which can make the determined pre-charge voltage closer to the actual voltage of the battery pack.

[0013] In combination with the first aspect and the above-mentioned implementation methods, in some possible implementation methods, the target pre-charge voltage is determined based on the predicted pre-charge voltage and the battery pack temperature, including: when the battery pack temperature is less than or equal to a first preset temperature, or when the battery pack temperature is greater than or equal to a second preset temperature, determining the target adjustment voltage based on the battery pack temperature, the first preset temperature is less than the second preset temperature; determining the target pre-charge voltage based on the predicted pre-charge voltage and the target adjustment voltage; when the battery pack temperature is greater than the first preset temperature and less than the second preset temperature, determining the target pre-charge voltage to be the predicted pre-charge voltage.

[0014] In the above technical solution, the operating temperature of the power battery will have a great impact on the voltage of the power battery. In a low temperature environment, the chemical reaction rate inside the battery slows down, and the internal resistance of the power battery increases significantly, resulting in a greater voltage drop during charging, which affects the setting of the pre-charge voltage. In a high temperature environment, the internal resistance of the battery is reduced, so that the charging current can be higher, and the temperature of the power battery is prone to rise, resulting in the risk of thermal runaway of the power battery. Therefore, when determining the target pre-charge voltage, the vehicle can also detect whether the power battery is in a low temperature environment or a high temperature environment. When the power battery is in a low temperature environment or a high temperature environment, the vehicle can appropriately reduce the pre-charge voltage to avoid a large pre-charge voltage in a low temperature environment causing the current to rise too quickly and produce a large voltage drop, or to avoid the charging current from increasing too quickly in a high temperature environment to prevent the battery temperature from further increasing.

[0015] In combination with the first aspect and the above-mentioned implementation methods, in some possible implementation methods, the method also includes: when the pre-charging time is equal to the third preset time, judging whether the power battery is pre-charged successfully based on the actual voltage of the battery pack; when the power battery is pre-charged successfully, controlling the power battery to switch from the pre-charging stage to the formal charging stage; when the power battery is not pre-charged successfully, stopping charging the power battery.

[0016] In the above technical solution, after pre-charging is complete, the vehicle needs to further determine whether the power battery pre-charging was successful. If the pre-charging is successful, the power battery is controlled to enter the main charging phase. Conversely, if the pre-charging fails, the power battery is controlled to stop charging. This process can promptly detect power battery pre-charging failures and prevent the power battery from mistakenly entering the main charging phase, which may damage the power battery performance.

[0017] In combination with the first aspect and the above-mentioned implementation methods, in some possible implementation methods, the judgment of whether the power battery is pre-charged successfully is made based on the actual voltage of the battery pack, including: determining the voltage ratio of the actual voltage of the battery pack to the nominal voltage of the battery pack; when the voltage ratio is within a preset ratio range, determining that the power battery is pre-charged successfully; when the ratio is not within the preset ratio range, determining that the power battery is not pre-charged successfully.

[0018] In a second aspect, a device for pre-charging a vehicle power battery is provided, which includes: a parameter acquisition module, which is used to obtain the pre-charging time of the power battery and the operating parameters of the battery pack of the power battery when the power battery is in the pre-charging stage, and the battery pack operating parameters are used to indicate the operating state of the battery pack of the power battery; a voltage determination module, which is used to determine a target pre-charging voltage based on the pre-charging time and the battery pack operating parameters, and the difference between the target pre-charging voltage and the actual voltage of the battery pack is less than or equal to a first voltage difference; and a charging module, which is used to send the target pre-charging voltage to a charging pile so that the charging pile charges the power battery at the target pre-charging voltage.

[0019] In combination with the second aspect, in some possible implementations, the battery pack operating parameters include the actual battery pack voltage and the battery pack temperature, and the voltage determination module is specifically used to: determine the predicted pre-charge voltage based on the pre-charge time and the actual battery pack voltage; determine the target pre-charge voltage based on the predicted pre-charge voltage and the battery pack temperature.

[0020] In combination with the second aspect and the above-mentioned implementation methods, in some possible implementation methods, the voltage determination module is also used to: determine the predicted pre-charge voltage as the actual voltage of the battery pack when the pre-charge time is less than or equal to the first preset time; determine the target voltage difference between the actual voltage of the battery pack and the second voltage difference when the pre-charge time is greater than the first preset time and less than or equal to the second preset time; determine the predicted pre-charge voltage as the voltage with the smaller value between the target voltage difference and the maximum voltage limit of the charging pile; determine the predicted pre-charge voltage as the voltage with the smaller value between the actual voltage of the battery pack and the maximum voltage limit of the charging pile when the pre-charge time is greater than the second preset time and less than or equal to the third preset time.

[0021] In combination with the second aspect and the above-mentioned implementation methods, in some possible implementation methods, the voltage determination module is also used to: determine a third voltage difference between the output voltage of the charging pile and the actual voltage of the battery pack when the pre-charging time is equal to the first preset time; determine a fourth voltage difference by looking up a table according to the identification of the power battery and the identification of the charging pile; and determine that the preset voltage difference is the sum of the third voltage difference and the fourth voltage difference.

[0022] In combination with the second aspect and the above-mentioned implementation methods, in some possible implementation methods, the voltage determination module is also used to: determine the target adjustment voltage according to the battery pack temperature when the battery pack temperature is less than or equal to a first preset temperature, or when the battery pack temperature is greater than or equal to a second preset temperature, and the first preset temperature is less than the second preset temperature; determine the target pre-charge voltage according to the predicted pre-charge voltage and the target adjustment voltage; and determine the target pre-charge voltage to be the predicted pre-charge voltage when the battery pack temperature is greater than the first preset temperature and less than the second preset temperature.

[0023] In combination with the second aspect and the above-mentioned implementation methods, in some possible implementation methods, the device also includes a pre-charging judgment module, which is used to judge whether the power battery is successfully pre-charged based on the actual voltage of the battery pack when the pre-charging time is equal to the third preset time; if the power battery is successfully pre-charged, control the power battery to switch from the pre-charging stage to the formal charging stage; if the power battery is not pre-charged successfully, stop charging the power battery.

[0024] In combination with the second aspect and the above-mentioned implementation methods, in some possible implementation methods, the pre-charge judgment module is specifically used to: determine the voltage ratio of the actual voltage of the battery pack to the nominal voltage of the battery pack; when the voltage ratio is within a preset ratio range, determine that the power battery is pre-charged successfully; when the ratio is not within the preset ratio range, determine that the power battery is not pre-charged successfully.

[0025] In a third aspect, a vehicle is provided, comprising a memory and a processor. The memory is configured to store executable program code, and the processor is configured to retrieve and execute the executable program code from the memory, so that the vehicle executes the method of the first aspect or any possible implementation of the first aspect.

[0026] In a fourth aspect, a computer program product is provided, comprising: a computer program code, which, when executed on a computer, enables the computer to execute the method in the first aspect or any possible implementation of the first aspect.

[0027] In a fifth aspect, a computer-readable storage medium is provided, which stores a computer program code. When the computer program code runs on a computer, the computer executes the method in the above-mentioned first aspect or any possible implementation of the first aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic diagram of a vehicle power battery pre-charging scenario provided by an embodiment of the present application;

[0029] Figure 2 This is a structural diagram of a system for controlling pre-charging of a vehicle power battery provided by an embodiment of the present application;

[0030] Figure 3 is a schematic flow chart of a method for pre-charging a vehicle power battery provided in an embodiment of the present application;

[0031] Figure 4 is a schematic flow chart of another method for pre-charging a vehicle power battery provided in an embodiment of the present application;

[0032] Figure 5 This is a schematic structural diagram of a vehicle power battery pre-charging device provided in an embodiment of the present application;

[0033] Figure 6 It is a structural schematic diagram of a vehicle provided in an embodiment of the present application. DETAILED DESCRIPTION

[0034] The following will clearly and thoroughly describe the technical solutions in this application in conjunction with the accompanying drawings. In the description of the embodiments of this application, unless otherwise specified, " / " means or, for example, A / B can mean A or B: "and / or" in the text is only a description of the association relationship of associated objects, indicating that there can be three relationships, for example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, in the description of the embodiments of this application, "multiple" means two or more than two.

[0035] In the following, the terms "first" and "second" are used for descriptive purposes only and should not be understood to imply or suggest relative importance or implicitly indicate the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features.

[0036] Before introducing the method of the embodiment of the present application, the professional terms that may be involved in the embodiment of the present application are first explained.

[0037] The nominal voltage of a battery pack refers to the typical voltage that a battery pack is expected to provide under standard operating conditions. It is the average voltage that the battery pack typically outputs during a normal charge and discharge cycle. The nominal voltage is not the maximum or minimum voltage of the battery pack, but rather represents the operating voltage level of the battery pack.

[0038] Pre-charge voltage: Before the vehicle officially starts charging, in order to protect the safety of the battery pack and charging system, the charging pile outputs a lower voltage to gradually charge the capacitor inside the battery pack.

[0039] Charging pile maximum voltage limit: The highest voltage that the charging pile can output is usually determined by hardware design and safety standards to ensure the safety of the charging process.

[0040] The following describes the application scenarios of the embodiments of the present application.

[0041] Figure 1 This is a schematic diagram of a vehicle power battery pre-charging scenario provided in an embodiment of the present application.

[0042] For example, Figure 1 As shown, vehicle 101 is a hybrid vehicle or an electric vehicle. If the power battery of vehicle 101 is low while driving, the user can drive to a charging location and connect the DC charging port on vehicle 101 to the DC charging gun on charging pile 102 to charge the power battery of vehicle 101.

[0043] When charging the power battery of vehicle 101, the charging station 102 generally has a pre-charging phase before the actual charging. There are two reasons for pre-charging the power battery: first, to prevent the power battery from being subjected to current shock; second, to protect the relay and switch.

[0044] Regarding the first reason mentioned above, power battery packs typically contain a large number of capacitors and other energy storage components. When charging the power battery, if charging station 102 directly applies a high voltage, these capacitors will instantly absorb a large amount of current, causing a current surge, which may damage the electronic components within the battery pack or cause a short circuit in the battery pack's internal wiring. Precharging can gradually charge these capacitors, causing their voltage to rise gradually, thus avoiding current surges.

[0045] Regarding the second reason mentioned above, the Battery Management System (BMS) uses multiple high-voltage relays to control the on / off of the circuit. If high voltage is applied directly to the BMS, the relays may be damaged by the high current surge, shortening their service life. Precharging reduces the voltage difference before the relay closes, thereby reducing arcing and sparking when the relay closes, thus protecting the relays and related components.

[0046] It should be understood that when precharging a power battery, ideally, the precharge voltage output by the charging station should be as close as possible to the actual battery pack voltage. Therefore, during the precharge process, as the power battery charge increases, the internal voltage of the power battery will gradually rise, and the actual battery pack voltage will also gradually rise. By controlling the precharge voltage during the precharge process to be equal to the actual battery pack voltage, a smooth transition of the battery pack voltage can be ensured.

[0047] During the actual charging process, there is a certain voltage difference between the pre-charge voltage and the actual voltage of the battery pack due to various factors, such as sensor measurement error, system response time, temperature, and the brand and model of the charging pile and power battery.

[0048] To address this issue, related technologies use a fixed offset to compensate for the voltage difference during pre-charging, so that the pre-charge voltage is determined by the actual battery pack voltage and the offset. Optionally, the offset is typically 1V.

[0049] When using the above method, the voltage deviation detected by the charging pile during the pre-charging process may be too large or too small, resulting in a failure in the pre-charging of the power battery. The above-mentioned voltage deviation detected by the charging pile is too large or too small, which refers to the voltage difference between the pre-charge voltage output by the charging pile and the actual voltage of the battery pack of the vehicle's power battery. The above-mentioned problem may occur due to the following reasons:

[0050] First, charging piles and battery packs of different brands may have different design standards and specifications. The fixed offset may not be suitable for all charging piles and battery packs, resulting in the voltage detected by some charging piles being too high or too low.

[0051] Second, the battery pack voltage fluctuates with temperature. Under extreme temperature conditions, a fixed offset may not be sufficient to compensate for this change, resulting in a large or small deviation between the pre-charge voltage and the actual battery pack voltage.

[0052] Third, the measurement accuracy of the sensor used for measurement may also be inaccurate, with certain measurement errors. Especially in harsh environments, a fixed offset cannot compensate for these errors, resulting in voltage deviation.

[0053] In summary, the above method of determining the pre-charge voltage cannot dynamically adjust the pre-charge voltage during the actual pre-charge process, and ignores the changes and potential risks of the power battery during the pre-charge process.

[0054] Based on the problems existing in the above-mentioned pre-charging process, an embodiment of the present application provides a method for pre-charging a vehicle power battery. This method can flexibly adjust the pre-charging voltage in real time during the power battery pre-charging process, thereby improving the pre-charging success rate of the power battery.

[0055] It should be understood that the method of the embodiment of the present application mainly relies on the interaction process between the system composed of the BMS and the charging pile in the vehicle. Before introducing a method for controlling the pre-charging of the vehicle power battery provided by the embodiment of the present application, the structure and working principle of the system relied on to implement the method are first introduced.

[0056] Figure 2This is a structural diagram of a system for controlling pre-charging of a vehicle power battery provided in an embodiment of the present application.

[0057] For example, Figure 2 As shown, a system 200 for controlling pre-charging of a vehicle power battery provided in an embodiment of the present application includes two major components, namely a charging pile 102 and a BMS 201 .

[0058] In one possible implementation, the BMS 201 may be divided into a power battery, a pre-charge relay, a charging capacitor, a main relay, a pre-charge resistor, and various sensors (such as a voltage sensor, a current sensor, and a temperature sensor) according to their functions.

[0059] Among them, the pre-charge relay is used to connect the circuit between the pre-charge resistor and the battery pack of the power battery, and is disconnected after the power battery pre-charge is completed to protect the resistor.

[0060] The main relay is used to control the on and off of the high-voltage circuit, ensuring that the high-voltage circuit is correctly closed or opened before and after the pre-charge stage.

[0061] The pre-charge resistor is used to limit the current during the pre-charge stage to prevent high current from impacting the battery pack and other components in the system.

[0062] The charging capacitor is used to smooth out power supply voltage fluctuations and ensure voltage stability, especially in the pre-charge stage, where it can absorb instantaneous voltage spikes and protect the battery pack and other electronic components.

[0063] The voltage sensor is used to monitor the voltage of each module in real time to ensure that the pre-charge voltage is set accurately.

[0064] The current sensor is used to monitor the charging current to ensure that it does not exceed the safety limits of the battery pack and the system.

[0065] The temperature sensor is used to monitor temperature changes in real time, ensure that the battery pack operates within a safe temperature range, and adjust the pre-charge voltage setting value according to temperature changes.

[0066] Based on the composition of the system 200, in the embodiment of the present application, when pre-charging the power battery, the specific pre-charging process is roughly as follows:

[0067] When the power battery of the vehicle is low on power, the user connects the DC charging port of the vehicle to the charging gun on the charging pile 102. After the connection is made, in order to ensure the safety and stability of the charging process, the battery management system 201 will first close the pre-charge relay and connect the pre-charge resistor to the circuit, thereby entering the pre-charge stage of the power battery.

[0068] During the pre-charging process, in the embodiment of the present application, the vehicle can be controlled so that the pre-charging voltage that the charging pile 102 needs to output is equal to the actual voltage of the battery pack within a period of time after the pre-charging starts. After a period of time, the BMS 201 records the deviation between the actual output voltage of the charging pile and the actual voltage of the battery pack at this time. In the following period of time, the vehicle dynamically determines the pre-charging voltage according to the actual voltage of the battery pack and the above-mentioned deviation value, as well as the maximum voltage limit of the charging pile. After the pre-charging reaches a certain time again, the vehicle determines the pre-charging voltage according to the actual voltage of the battery pack and the maximum voltage limit of the charging pile.

[0069] Therefore, through the above process, after the power battery pre-charging is completed, the pre-charging relay is disconnected, the main relay is closed, the power battery enters the formal charging stage, and the charging pile charges the battery pack with a higher voltage and current.

[0070] During the charging process, the BMS201 monitors the battery pack's voltage, current, temperature, and other parameters through various sensors to ensure battery safety. When the battery's State of Charge (SOC) reaches a certain value, the BMS201 disconnects the main relay, severing the high-voltage circuit and closing the communication connection between the charging station and the vehicle, halting the charging process.

[0071] After introducing the application scenarios and system structure of the embodiments of the present application, a method for pre-charging a vehicle power battery provided by the embodiments of the present application is introduced below.

[0072] Figure 3 This is a schematic flow chart of a method for pre-charging a vehicle power battery provided by an embodiment of the present application. It should be understood that this method can be applied to Figure 2 The BMS in the system can also be applied to any electronic control unit (ECU) in the vehicle.

[0073] For example, Figure 3 As shown, the method 300 includes:

[0074] 301 , when the power battery is in a pre-charging stage, obtain the pre-charging time of the power battery and the operating parameters of the battery pack of the power battery, where the operating parameters of the battery pack are used to indicate the operating status of the battery pack of the power battery.

[0075] During vehicle operation, the BMS can monitor the SOC of the power battery in real time. When the SOC value of the power battery is detected to be below a certain threshold, the BMS will prompt the user to charge it as soon as possible to avoid loss of power battery performance.

[0076] When charging the power battery, the user connects the vehicle's external charging port to the charging gun on the charging pile, thereby triggering the power battery charging process. The charging gun on the charging pile is an interface that matches the DC charging port on the vehicle. When connecting the vehicle's charging port and the charging gun on the charging pile, both interfaces must comply with the corresponding charging interface standards.

[0077] Optionally, according to the different charging interface standards, it can be divided into the combined charging system (CCS) interface standard, CHAdeMO or GB / T. Each DC interface standard corresponds to a different charging interface. Specifically, the charging interface on the vehicle corresponding to the CCS standard is the CCS2 charging interface, and the charging gun on the charging pile is also a CCS2 charging gun. The charging interface on the vehicle corresponding to the CHAdeMO standard is the CHAdeMO interface, and the charging gun on the charging pile is also a CHAdeMO charging gun. The charging interface on the vehicle corresponding to the GB / T standard is the GB / T interface, and the charging gun on the charging pile is also a GB / T charging gun. The embodiment of the present application does not limit the types of the two charging interfaces.

[0078] After the charging gun is connected to the DC charging port of the vehicle, the BMS can send a charging request to the charging pile through the standardized communication protocol corresponding to the current type of charging interface.

[0079] The charging pile and BMS perform a handshake and authenticate each other based on a standardized communication protocol. Once the authentication is successful, the BMS and charging pile establish a communication connection to prepare for the subsequent charging process.

[0080] After the charging process starts, in order to prevent the power battery from being impacted by large current, the BMS first closes the pre-charge relay in the system to control the power battery to enter the pre-charge stage.

[0081] It should be understood that when the power battery is in the pre-charging stage, if the pre-charging voltage output by the charging pile is directly set to a final fixed voltage, the power battery may be subjected to a large current shock, causing damage to the battery pack and electronic components. In addition, if the pre-charging method shown in the relevant technology is followed, the difference between the pre-charging voltage actually output by the charging pile and the actual voltage of the power battery will be too large. In order to avoid the above situation, the embodiment of the present application proposes a method for pre-charging a vehicle power battery, which can divide the pre-charging process into several different stages during the power battery charging process, and determine different pre-charging voltages in each stage, so that the pre-charging voltage can be dynamically adjusted in time according to the actual situation at different charging stages during the pre-charging process.

[0082] In a possible implementation, the pre-charging process is divided into several stages according to the total pre-charging duration of the pre-charging stages.

[0083] It should be understood that the pre-charging process of a power battery generally lasts for a short time. Based on actual vehicle testing, technicians can set a fixed pre-charging duration and store it in the BMS as the total pre-charging duration. Optionally, in the embodiment of this application, the total pre-charging duration can be 20 seconds. The process of dividing the total pre-charging duration is described below.

[0084] Based on the segmented adjustment of the pre-charge voltage in the embodiments of the present application, during the power battery charging process, the BMS can obtain the pre-charge duration of the power battery in real time to determine which pre-charge stage the power battery is currently in. In addition to the pre-charge duration, the state of the power battery pack during the pre-charge process will also directly affect the pre-charge voltage. Therefore, the BMS can also obtain the operating parameters of the power battery pack. Among them, the battery pack operating parameters are used to indicate the operating status of the power battery pack.

[0085] Optionally, the battery pack operating parameters include the actual battery pack voltage and the battery pack temperature.

[0086] It should be understood that during the power battery pre-charging process, the battery pack temperature has a crucial impact on the pre-charge voltage. This is because temperature affects the power battery's internal resistance, voltage characteristics, and chemical reaction rate. In low-temperature environments, the power battery's internal resistance increases significantly, resulting in a larger voltage drop during charging, which affects the pre-charge voltage setting. In high-temperature environments, the battery's internal resistance decreases, allowing for higher charging currents. This increases the power battery's temperature and can lead to the risk of thermal runaway.

[0087] Therefore, during the pre-charging process of the power battery, the BMS not only needs to consider the changes in the actual voltage of the battery pack, but also needs to take into account the changes in the temperature of the battery pack.

[0088] The actual battery pack voltage refers to the actual voltage of the power battery. In a vehicle, the multiple cells in a power battery pack are typically connected in series. Therefore, the actual battery pack voltage is the total voltage of all the cells connected in series.

[0089] For example, during the pre-charging process, the BMS may collect the actual voltage of the single cell through the voltage sensor of the single cell, and calculate the actual voltage of the battery pack.

[0090] For example, the BMS may obtain the battery pack temperature by collecting the temperature of the battery pack through a temperature sensor inside the power battery.

[0091] For example, with respect to the pre-charging duration, after the pre-charging starts, the BMS may time the pre-charging process using a built-in timer to obtain the pre-charging duration.

[0092] 302 , determining a target pre-charge voltage according to the pre-charge duration and the operating parameters of the battery pack, wherein the difference between the target pre-charge voltage and the actual voltage of the battery pack is less than or equal to a first voltage difference.

[0093] In combination with the impact of battery pack temperature on the power battery pre-charging process in the above description, when determining the target pre-charging voltage, the BMS can determine the final target pre-charging voltage based on the pre-charging time, the actual battery pack voltage and the battery pack temperature.

[0094] In one possible implementation, determining a target pre-charge voltage based on the pre-charge duration and battery pack operating parameters includes:

[0095] Determine the predicted pre-charge voltage based on the pre-charge time and the actual voltage of the battery pack;

[0096] Determine the target pre-charge voltage based on the predicted pre-charge voltage and battery pack temperature.

[0097] The predicted pre-charge voltage is the ideal pre-charge voltage determined without considering the influence of the battery pack temperature on the pre-charge voltage.

[0098] When determining the target pre-charge voltage, the BMS can first determine the predicted pre-charge voltage based on the pre-charge duration and the actual battery pack voltage. It then considers the influencing factor of the battery pack temperature to arrive at the final target pre-charge voltage.

[0099] Specifically, when determining the predicted pre-charge voltage based on the pre-charge time and the actual voltage of the battery pack, based on the stage division of the total pre-charge time in the embodiment of the present application, the BMS can first determine the pre-charge stage of the current power battery based on the pre-charge time, and then determine the predicted pre-charge voltage based on the target pre-charge voltage determination method corresponding to the current pre-charge stage, combined with the actual voltage of the battery pack.

[0100] In one possible implementation, the predicted pre-charge voltage of the charging pile is determined based on the pre-charge duration and the actual voltage of the battery pack, including:

[0101] When the pre-charge duration is less than or equal to the first preset duration, determining the predicted pre-charge voltage as the actual voltage of the battery pack;

[0102] When the pre-charge duration is greater than the first preset duration and less than or equal to the second preset duration, determining a target voltage difference between the actual battery pack voltage and the second voltage difference; and determining the predicted pre-charge voltage as the smaller voltage between the target voltage difference and the maximum voltage limit of the charging pile;

[0103] When the pre-charge time is greater than the second preset time and less than or equal to the third preset time, the predicted pre-charge voltage is determined to be the smaller voltage between the actual voltage of the battery pack and the maximum voltage limit of the charging pile.

[0104] The total pre-charging time is pre-stored in the BMS. When implementing the method of the embodiment of the present application, based on the total pre-charging time, technicians can divide the total pre-charging time into several different stages based on the actual needs of the power battery pre-charging process, and each stage occupies a different proportion of the total pre-charging time.

[0105] Optionally, in the embodiment of the present application, the total pre-charging time can be divided into three stages, each stage accounting for 25%, 25% and 50% of the total pre-charging time respectively, referred to as the "first pre-charging stage", the "second pre-charging stage" and the "third pre-charging stage" respectively.

[0106] Specifically, the total pre-charging time is 20s, the pre-charging time corresponding to the first pre-charging stage is 0-5s, the pre-charging time corresponding to the second pre-charging stage is 5-10s, and the pre-charging time corresponding to the third pre-charging stage is 10-20s.

[0107] The end time of the first pre-charging stage is the first preset duration, i.e., 5 seconds; the end time of the second pre-charging stage is the second preset duration, i.e., 10 seconds; the end time of the third pre-charging stage is the third preset duration, i.e., 20 seconds.

[0108] For different pre-charge stages, the corresponding pre-charge voltage is determined in different ways. The pre-charge voltage in each pre-charge stage is determined as follows:

[0109] In the first pre-charge phase, the BMS in this embodiment can control the predicted pre-charge voltage to be equal to the actual battery pack voltage. This is because the first pre-charge phase is the initial pre-charge phase. During the first 5 seconds, the BMS controls the predicted pre-charge voltage to be equal to the actual battery pack voltage, minimizing the voltage difference between the battery pack and the charging station, thus preventing the power battery from being subjected to high current shocks during the initial pre-charge period.

[0110] Therefore, when the BMS determines that the pre-charge duration is in the first pre-charge stage, that is, the pre-charge duration is less than or equal to the first preset duration, it can determine the predicted pre-charge voltage based on the obtained actual voltage of the battery pack.

[0111] For example, if the BMS obtains a pre-charge time of 3 seconds and the actual voltage of the battery pack is 250V, the predicted pre-charge voltage is also determined to be 250V.

[0112] In the second pre-charging stage, in the embodiment of the present application, the predicted pre-charging voltage can be obtained by the actual voltage and deviation value of the battery pack.

[0113] The following first explains the process of obtaining the above deviation value.

[0114] In one possible implementation, the step of determining the second voltage difference includes:

[0115] When the pre-charging time is equal to the first preset time, determining a third voltage difference between the output voltage of the charging pile and the actual voltage of the battery pack;

[0116] According to the identification of the power battery and the identification of the charging pile, a fourth voltage difference is determined by looking up a table;

[0117] The second voltage difference is determined to be the sum of the third voltage difference and the fourth voltage difference.

[0118] The second voltage difference is the deviation value of the second pre-charge stage.

[0119] Specifically, when the pre-charging time is equal to the first preset time, that is, after the first pre-charging stage ends, the BMS can record a third voltage difference between the current output voltage of the charging pile and the actual voltage of the battery pack.

[0120] The charging pile output voltage refers to the voltage set and output by the charging pile based on the vehicle's request and its own capabilities. Ideally, the charging pile output voltage should equal the desired pre-charge voltage sent by the BMS to the charging pile. However, in actual charging, the charging pile's voltage regulation system has certain accuracy limitations and cannot achieve completely accurate voltage output. Therefore, the actual charging pile output voltage may deviate from the desired pre-charge voltage sent by the BMS. For example, if the desired pre-charge voltage sent by the BMS is 305V, the actual output voltage of the charging pile may be 304.8V.

[0121] Furthermore, the voltage output by the charging pile may experience voltage loss during transmission. For example, the resistance of the charging cable can cause a voltage drop, as can the resistance of the charging connector and relay. Therefore, the output voltage of the charging pile is not exactly equal to the voltage actually reaching the power battery. Consequently, the voltage output by the charging pile is not completely equal to the voltage reaching the power battery, resulting in a certain error between the output voltage of the charging pile and the actual voltage of the battery pack. Therefore, during the pre-charging process, to avoid a large difference between the output voltage of the charging pile and the actual voltage of the battery pack, the BMS needs to promptly record this error.

[0122] For example, for the output voltage of the charging pile, the BMS may request to obtain the output voltage of the charging pile at the current moment by sending a data request to the charging pile.

[0123] After obtaining the charging pile output voltage and the actual battery pack voltage, the BMS can calculate a third voltage difference between the current charging pile output voltage and the actual battery pack voltage.

[0124] Specifically, the third voltage difference = the output voltage of the charging pile - the actual voltage of the battery pack.

[0125] Therefore, after the pre-charging time reaches 5s, the BMS can record the third voltage difference between the output voltage of the charging pile and the actual voltage of the battery pack at this moment to determine the voltage difference between the output voltage of the charging pile and the actual voltage of the battery pack at the current moment.

[0126] In addition, affected by the brand and model of the power battery and charging pile, in order to compensate for the differences between charging piles and power batteries of different brands, the pre-charge voltage also needs to be fine-tuned.

[0127] In the embodiment of the present application, technicians can preset the voltage deviation values ​​corresponding to different brands and models of power batteries and charging piles.

[0128] During the pre-charging process, the BMS can also obtain the identification of the power battery and the identification of the charging pile. The identification specifically refers to the identity document (ID) or serial number (SN).

[0129] After obtaining the identifiers of the power battery and the charging pile, the BMS can obtain the voltage deviation value of the current brand and model of the power battery and the charging pile, that is, the fourth voltage difference, by looking up the table.

[0130] After obtaining the third voltage difference and the fourth voltage difference, the BMS obtains the second voltage difference by summing the third voltage difference and the fourth voltage difference.

[0131] When determining the pre-charge voltage, there is already a voltage deviation between the charging pile output voltage and the actual battery pack voltage of the power battery. In order to reduce the charging pile output voltage as close as possible to the actual battery pack voltage, the BMS needs to gradually reduce the charging pile output voltage. Therefore, the BMS can calculate the voltage difference between the actual battery pack voltage and the above-mentioned preset voltage difference.

[0132] In addition, charging piles generally have a corresponding maximum voltage limit for the charging pile. This voltage is the limit voltage value of the charging pile during operation. The voltage output by the charging pile during the pre-charging process should not exceed the maximum voltage limit of the charging pile. If the pre-charging time is within the period of 5-10s, it means that the pre-charging stage is the second pre-charging stage. During this stage, due to the increase in the charge amount inside the power battery, the power battery temperature rises and the voltage increases. In this case, the BMS also needs to take the maximum voltage limit of the charging pile into consideration when determining the predicted pre-charging voltage.

[0133] For example, the maximum voltage limit of the charging pile is generally a property of the charging pile itself. The BMS can obtain the maximum voltage limit of the charging pile by sending a request for obtaining the maximum voltage limit to the charging pile.

[0134] After obtaining the maximum voltage limit of the charging pile, to ensure that the charging pile output voltage is minimized to approach the actual battery pack voltage, the BMS can select the smaller voltage between the maximum voltage limit of the charging pile and the difference between the actual battery pack voltage and the preset voltage as the predicted pre-charge voltage. That is, predicted pre-charge voltage = min{actual battery pack voltage - preset voltage difference, maximum voltage limit of the charging pile}.

[0135] Therefore, the method of determining the predicted pre-charge voltage in the above-mentioned second pre-charge stage can gradually reduce the difference between the output voltage of the charging pile and the actual voltage of the battery pack, so that the pre-charge voltage gradually approaches the actual voltage of the battery pack.

[0136] For example, assume the maximum voltage limit of the charging pile is 750V. If the second voltage difference is 1V, the actual battery pack voltage is 300V, and the charging pile output voltage is 305V, then the first voltage difference is 5V. Therefore, the predicted charging voltage = 300-5-1 = 294V. Thus, through the above process, the originally higher charging pile output voltage can be controlled to decrease during the pre-charge process, gradually approaching the actual battery pack voltage, thereby reducing the voltage difference.

[0137] In the third pre-charge stage, in the embodiment of the present application, the predicted pre-charge voltage can be obtained by the actual battery pack voltage and the maximum voltage limit of the charging pile. The predicted pre-charge voltage is specifically the smaller voltage between the actual battery pack voltage and the maximum voltage limit of the charging pile.

[0138] During the pre-charging process, if the BMS determines that the current pre-charging time is between 10-20s, assuming that the actual voltage of the battery pack is 400V and the maximum voltage limit of the charging pile is 750V, the predicted pre-charging voltage is 400V.

[0139] The reason for setting the predicted pre-charge voltage to the minimum of the actual battery pack voltage and the maximum voltage limit of the charging pile in the third pre-charge stage is that when the pre-charge enters the third pre-charge stage, the final pre-charge stage has been reached. In this case, the voltage difference between the output voltage of the charging pile and the actual voltage of the battery pack has decreased through the adjustment process of the second pre-charge stage. Therefore, in the final pre-charge stage, the BMS only needs to control the pre-charge voltage not to exceed the safety limit of the charging pile or battery pack to prepare for the subsequent closure of the main relay.

[0140] In the above technical solution, since during the power battery charging process, when the voltage is transmitted from the charging pile to the power battery end, a voltage drop will occur due to the wiring harness and other factors, resulting in the output voltage of the charging pile not being equal to the voltage reaching the battery pack. Therefore, in order to avoid this situation where the difference between the actual voltage of the battery pack and the output voltage of the charging pile becomes larger and larger, resulting in inaccurate pre-charge voltage, the vehicle can record the voltage difference between the output voltage of the charging pile and the actual voltage of the battery pack during the pre-charge process, so as to facilitate timely adjustment during the pre-charge process. In addition, due to the influence of the battery pack brand and the charging pile brand, there will also be an error between the output voltage of the charging pile and the actual voltage of the battery pack. Therefore, when determining the pre-charge voltage, the embodiment of the present application takes into account the combined influence of the two voltage errors, which can make the determined pre-charge voltage closer to the actual voltage of the battery pack.

[0141] Specifically, during the power battery charging process, if the current pre-charge duration is less than or equal to the first preset duration, it means that the current power battery is in the initial pre-charge stage. In this stage, the predicted pre-charge voltage is controlled to be the actual voltage of the battery pack, ensuring that no voltage difference is generated in the initial pre-charge stage, thereby avoiding the risk of current shock and arc generation in the power battery. When the pre-charge duration is greater than the first preset duration and less than the second preset duration, by calculating the target voltage difference and selecting the smaller voltage as the predicted pre-charge voltage, the difference between the output voltage of the charging pile and the actual voltage of the battery pack can also be reduced. When the pre-charge duration is greater than the second preset duration but less than the third preset duration, the predicted pre-charge voltage is the smaller voltage between the actual voltage of the battery pack and the maximum voltage limit of the charging pile, ensuring that the pre-charge voltage can be close to the actual voltage of the battery pack and completing the pre-charge process. Therefore, the above process can dynamically adjust the pre-charge voltage at each stage of the pre-charge process to ensure that the voltage difference between the pre-charge voltage (or the output voltage of the charging pile) and the actual voltage of the battery pack can be controlled within a reasonable range, thereby improving the pre-charge success rate of the power battery.

[0142] Therefore, through the above process, the BMS can determine the predicted pre-charge voltage of the power battery in different pre-charge stages.

[0143] After obtaining the predicted pre-charge voltage, the BMS can further determine the target pre-charge voltage based on the battery pack temperature.

[0144] In one possible implementation, determining a target pre-charge voltage based on the predicted pre-charge voltage and the battery pack temperature includes:

[0145] When the battery pack temperature is less than or equal to the first preset temperature, or the battery pack temperature is greater than or equal to the second preset temperature, the target adjustment voltage is determined according to the battery pack temperature, and the first preset temperature is less than the second preset temperature; the target pre-charge voltage is determined according to the predicted pre-charge voltage and the target adjustment voltage.

[0146] When the battery pack temperature is greater than the first preset temperature and less than the second preset temperature, the target pre-charge voltage is determined to be the predicted pre-charge voltage.

[0147] As can be seen from the above description, in low-temperature environments, the chemical reaction rate within the battery slows down, significantly increasing the internal resistance of the power battery. This results in a larger voltage drop during charging, affecting the setting of the pre-charge voltage. In high-temperature environments, the internal resistance of the battery decreases, allowing for higher charging currents. This increases the power battery temperature and leads to the risk of thermal runaway.

[0148] Specifically, under normal circumstances, when the battery pack temperature is below 0°C, it is considered that the power battery is currently operating in a low-temperature environment; when the battery pack temperature is above 45°C, it is considered that the power battery is currently operating in a high-temperature environment. Based on this, in this embodiment of the application, 0°C can be used as the first preset temperature to determine whether the battery pack temperature is too low, and 45°C can be used as the second preset temperature to determine whether the battery pack temperature is too high. The first and second preset temperatures are stored in the BMS.

[0149] Low temperatures significantly increase the internal resistance of power batteries, and low temperatures can easily lead to electrode surface passivation. A higher pre-charge voltage can lead to a rapid current increase and a larger voltage drop, resulting in a larger current surge. Therefore, appropriately lowering the pre-charge voltage in low-temperature environments can slow the temperature rise of the power battery and improve electrode activity.

[0150] Because the internal resistance of the power battery decreases in high-temperature environments, higher charging currents can be achieved. Excessively high temperatures can accelerate chemical reactions within the battery, causing the temperature to rise further. Therefore, appropriately lowering the pre-charge voltage in high-temperature environments can reduce the charging current and prevent further increases in battery temperature.

[0151] Therefore, during the pre-charging process of the power battery, the BMS can detect the battery pack temperature in real time and compare it with the first preset temperature and the second preset temperature respectively to determine whether the power battery is operating in a low temperature or high temperature environment.

[0152] When the BMS determines that the current battery pack temperature is less than or equal to 0°C, it determines that the power battery is currently operating in a low-temperature environment. Alternatively, when the BMS determines that the battery pack temperature is greater than or equal to 45°C, it determines that the power battery is currently operating in a high-temperature environment.

[0153] In this case, the BMS needs to appropriately reduce the pre-charge voltage sent by the power battery to the charging pile.

[0154] Specifically, in the embodiment of the present application, a plurality of regulating voltages corresponding to low temperature intervals, ie, voltages that need to be reduced, and a plurality of regulating voltages corresponding to high temperature intervals may be preset.

[0155] When it is determined that the power battery is currently operating in a low-temperature environment, the BMS can determine the low-temperature range of the battery pack temperature based on the battery pack temperature, and determine the target regulation voltage based on the low-temperature range. Similarly, when it is determined that the power battery is currently operating in a high-temperature environment, the BMS can determine the high-temperature range of the battery pack temperature based on the battery pack temperature, and determine the target regulation voltage based on the high-temperature range.

[0156] After determining the target regulation voltage, the BMS can calculate the difference between the predicted pre-charge voltage and the target regulation voltage to obtain the target pre-charge voltage that ultimately needs to be sent to the charging pile.

[0157] In another case, when the battery pack temperature is between 0°C and 45°C, it indicates that the current battery pack operating temperature is normal and there is no need to reduce the pre-charge voltage. Therefore, the BMS can directly determine the predicted pre-charge voltage as the target pre-charge voltage.

[0158] In the above technical solution, the operating temperature of the power battery will have a great impact on the voltage of the power battery. In a low temperature environment, the chemical reaction rate inside the battery slows down, and the internal resistance of the power battery increases significantly, resulting in a greater voltage drop during charging, which affects the setting of the pre-charge voltage. In a high temperature environment, the internal resistance of the battery is reduced, so that the charging current can be higher, and the temperature of the power battery is prone to rise, resulting in the risk of thermal runaway of the power battery. Therefore, when determining the target pre-charge voltage, the vehicle can also detect whether the power battery is in a low temperature environment or a high temperature environment. When the power battery is in a low temperature environment or a high temperature environment, the vehicle can appropriately reduce the pre-charge voltage to avoid a large pre-charge voltage in a low temperature environment causing the current to rise too quickly and produce a large voltage drop, or to avoid the charging current from increasing too quickly in a high temperature environment to prevent the battery temperature from further increasing.

[0159] Therefore, through the above method, the BMS can obtain the target pre-charge voltage expected during the pre-charging process of the power battery, and since the predicted pre-charge voltage is relatively close to the actual voltage of the battery pack in any pre-charging stage, and the voltage adjustment corresponding to the temperature factor is usually only a small adjustment, the voltage difference between the target pre-charge voltage determined by the BMS and the actual voltage of the battery pack can be guaranteed to be within a reasonable range.

[0160] 303 : Send the target pre-charge voltage to the charging pile, so that the charging pile charges the power battery at the target pre-charge voltage.

[0161] Based on the target pre-charge voltage determined in 302 , the BMS may send the target pre-charge voltage to the charging pile, so that the charging pile outputs a voltage according to the target pre-charge voltage to charge the power battery.

[0162] Combined with the above description, it can be seen that the total pre-charge time in the embodiment of the present application is generally 20s. Then, during the power battery pre-charging process, if the BMS detects that the pre-charge time is equal to the total pre-charge time, it can also determine whether the current power battery pre-charge is successful.

[0163] In one possible implementation, the method further includes:

[0164] When the pre-charging time is equal to the third preset time, judging whether the power battery is pre-charged successfully according to the actual voltage of the battery pack;

[0165] If the power battery is pre-charged successfully, control the power battery to switch from the pre-charging stage to the formal charging stage;

[0166] If the power battery is not pre-charged successfully, charging of the power battery is stopped.

[0167] The third preset duration is the end time of the third pre-charging stage, that is, the total pre-charging duration.

[0168] When the BMS detects that the current pre-charge time reaches 20s, it needs to determine whether the power battery pre-charge is successful based on the actual voltage of the current battery pack.

[0169] It should be understood that during the power battery pre-charging process, the final pre-charge voltage will vary depending on the design of different vehicle models and vehicle manufacturers. Generally, the final pre-charge voltage can be set as a proportional value of the battery pack's nominal voltage. The final pre-charge voltage here refers to the theoretical voltage that the battery pack can reach after the pre-charge is completed. The battery pack nominal voltage refers to the typical voltage value expected to be provided by the battery pack under standard operating conditions. It is the average voltage normally output by the battery pack during a normal charge and discharge cycle.

[0170] For example, in general, the nominal voltage of a battery pack is calculated based on the number and connection method of the individual cells within the power battery. When the individual cells of a power battery are connected in series, the nominal voltage of the battery pack is specifically equal to the nominal voltage of the individual cell multiplied by the number of individual cells. The nominal voltage of the individual cell is an inherent parameter pre-set by the power battery manufacturer during the production process. Therefore, the BMS can obtain the nominal voltage of the individual cell by obtaining it. Finally, the nominal voltage of the battery pack is calculated by combining the nominal voltage of the individual cell and the number of individual cells.

[0171] Optionally, in the embodiment of the present application, the final pre-charge voltage can be set to 90% of the nominal voltage of the battery pack. For example, assuming the nominal voltage of the battery pack is 400V, the final pre-charge voltage is 360V.

[0172] When the pre-charging time reaches the total pre-charging time, the BMS can use the actual voltage of the current battery pack to determine whether the power battery is pre-charged successfully.

[0173] In one possible implementation, determining whether the power battery is pre-charged successfully based on the actual voltage of the battery pack includes:

[0174] Determine the voltage ratio of the actual battery pack voltage to the nominal battery pack voltage;

[0175] When the difference between the voltage ratio and the preset voltage ratio is within a preset difference range, determining that the power battery pre-charging is successful;

[0176] If the ratio is not within the preset difference range, it is determined that the power battery is not pre-charged successfully.

[0177] When the pre-charge time reaches the total pre-charge time, the BMS can calculate the voltage ratio of the current battery pack actual voltage to the battery pack nominal voltage to determine the proportion of the current battery pack actual voltage to the battery pack nominal voltage.

[0178] Since the final pre-charge voltage is generally 90% of the battery pack's nominal voltage, the voltage ratio of the current battery pack's actual voltage to the battery pack's nominal voltage is calculated. If the calculated voltage ratio is equal to 90%, it means the current battery pack's actual voltage is equal to the final pre-charge voltage, indicating that the power battery pre-charge is successful.

[0179] In addition, during the actual pre-charging process, taking into account the performance of the power battery and charging pile, as well as the voltage loss during transmission, the pre-charging voltage can be allowed to fluctuate within a certain range.

[0180] Optionally, in the embodiment of the present application, a preset ratio range is pre-set to 88%-90%. In other words, in the embodiment of the present application, after the pre-charging is completed, if the BMS detects that the ratio of the actual battery pack voltage to the nominal battery pack voltage is within the preset ratio range, it indicates that the power battery pre-charging is successful. On the contrary, when the ratio of the actual battery pack voltage to the nominal battery pack voltage is not within the above-mentioned preset ratio range, it indicates that the difference between the actual battery pack voltage and the final pre-charging voltage is large, and the BMS determines that the power battery pre-charging has failed.

[0181] For example, the nominal voltage of the battery pack is 400V. Assuming that the current actual voltage of the battery pack is 320V, the BMS calculates that the ratio of the actual voltage of the battery pack to the nominal voltage of the battery pack is 80%. This ratio is not within the above-mentioned preset ratio range, so the BMS determines that the power battery pre-charge is not successful. Assuming that the current actual voltage of the battery pack is 354V, the BMS calculates that the ratio of the actual voltage of the battery pack to the nominal voltage of the battery pack is 88.5%. This ratio is within the above-mentioned preset ratio range, so the BMS determines that the power battery pre-charge is successful.

[0182] Furthermore, when the BMS determines that the power battery pre-charging is successful, the pre-charging relay is disconnected and the main relay is closed, controlling the power battery to enter the formal charging stage. When the BMS determines that the power battery is not pre-charged successfully, the pre-charging process is stopped, and the target prompt information is generated according to the current actual voltage of the battery pack and the nominal voltage of the battery pack. The BMS can control the on-board host in the vehicle to display a text pop-up window of the target prompt information, such as a text pop-up window of "The current power battery pre-charging failed, please deal with it in time", and / or, the BMS can also control the audio playback device in the vehicle to broadcast the voice of the target prompt information, such as the voice of "The current power battery pre-charging failed, please deal with it in time". In addition, the BMS can also send the target prompt information to the user's terminal device through the telematics box (T-box) in the vehicle, so that the user can receive the current pre-charging failure message in time to avoid delaying the user's normal use of the vehicle.

[0183] In the above technical solution, after pre-charging is complete, the vehicle needs to further determine whether the power battery pre-charging was successful. If the pre-charging is successful, the power battery is controlled to enter the main charging phase. Conversely, if the pre-charging fails, the power battery is controlled to stop charging. This process can promptly detect power battery pre-charging failures and prevent the power battery from mistakenly entering the main charging phase, which may damage the power battery performance.

[0184] In summary, during the charging process of the vehicle power battery, the present application proposes a method for pre-charging the vehicle power battery, in which the vehicle can obtain the pre-charging time and battery pack operating parameters of the power battery during the pre-charging process, and dynamically adjust the target pre-charging voltage of the power battery according to the pre-charging time and battery pack operating parameters. In the above process, the pre-charging voltage of the battery pack can be flexibly determined according to the actual operating conditions of the battery pack, so that the pre-charging voltage matches the current operating environment of the battery pack. Finally, the vehicle sends the target pre-charging voltage to the charging pile, which enables the charging pile to reasonably output the corresponding pre-charging voltage according to the current needs of the power battery, thereby reducing the voltage difference between the actual voltage of the battery pack and the output voltage of the charging pile, and improving the charging efficiency and success rate of the power battery.

[0185] In order to better understand the solution of the embodiment of the present application, Figure 4 The pre-charging process of the embodiment of the present application is described in detail.

[0186] Figure 4 This is a schematic flowchart of another method for pre-charging a vehicle power battery provided in an embodiment of the present application.

[0187] For example, Figure 4 As shown, the method 400 includes:

[0188] 401 , when the power battery is in a pre-charging stage, obtain the pre-charging time of the power battery and the operating parameters of the battery pack of the power battery, where the operating parameters of the battery pack are used to indicate the operating status of the battery pack of the power battery.

[0189] 402 : When the pre-charge duration is less than or equal to a first preset duration, determine the predicted pre-charge voltage as the actual voltage of the battery pack.

[0190] 403. When the pre-charging time is equal to the first preset time, record a third voltage difference between the output voltage of the charging pile and the actual voltage of the battery pack, and determine a fourth voltage difference based on the identification of the charging pile and the identification of the power battery.

[0191] 404. When the pre-charge time is greater than the first preset time and less than or equal to the second preset time, determine the target voltage difference between the actual voltage of the battery pack and the second voltage difference; determine the predicted pre-charge voltage as the smaller voltage between the target voltage difference and the maximum voltage limit of the charging pile.

[0192] 405 , when the pre-charge time is greater than the second preset time and less than or equal to the third preset time, determine the predicted pre-charge voltage as the smaller voltage between the actual voltage of the battery pack and the maximum voltage limit of the charging pile.

[0193] 406 , judging whether the battery pack is at a low temperature or a high temperature according to the battery pack temperature.

[0194] When the battery pack is at a low temperature or a high temperature, execute step 407;

[0195] When the battery pack is at a low temperature or a high temperature, steps 408 - 409 are executed.

[0196] 407 : When the battery pack temperature is greater than the first preset temperature and less than the second preset temperature, determine the target pre-charge voltage as the predicted pre-charge voltage.

[0197] 408. When the battery pack temperature is less than or equal to the first preset temperature, or the battery pack temperature is greater than or equal to the second preset temperature, determine the target regulation voltage according to the battery pack temperature, and the first preset temperature is less than the second preset temperature.

[0198] 409, determining a target pre-charge voltage according to the predicted pre-charge voltage and the target regulation voltage;

[0199] 410 , sending the target pre-charge voltage to the charging pile, and after the pre-charge time reaches a third preset time, determining whether the power battery is pre-charged successfully.

[0200] If the power battery is pre-charged successfully, execute step 411;

[0201] If the power battery is not pre-charged successfully, step 412 is executed.

[0202] 411, when the power battery is pre-charged successfully, control the power battery to switch from the pre-charging stage to the formal charging stage;

[0203] 412 , if the power battery is not pre-charged successfully, stop charging the power battery.

[0204] 401-412 in the above method 400 and 301-303 in the method 300 have the same inventive concept. For details, please refer to the introduction of the above method 300 and will not be repeated here.

[0205] Figure 5 It is a structural schematic diagram of a vehicle power battery pre-charging device provided in an embodiment of the present application.

[0206] For example, Figure 5 As shown, the apparatus 500 includes:

[0207] a parameter acquisition module 501, configured to acquire, when the power battery is in the pre-charging stage, the pre-charging duration of the power battery and the operating parameters of the battery pack of the power battery, wherein the operating parameters of the battery pack are used to indicate the operating status of the battery pack of the power battery;

[0208] a voltage determination module 502, configured to determine a target pre-charge voltage according to the pre-charge duration and the operating parameters of the battery pack, wherein the difference between the target pre-charge voltage and the actual voltage of the battery pack is less than or equal to a first voltage difference;

[0209] The charging module 503 is configured to send the target pre-charge voltage to a charging pile, so that the charging pile charges the power battery at the target pre-charge voltage.

[0210] In one possible implementation, the battery pack operating parameters include the actual battery pack voltage and the battery pack temperature, and the voltage determination module 502 is specifically used to: determine the predicted pre-charge voltage based on the pre-charge time and the actual battery pack voltage; and determine the target pre-charge voltage based on the predicted pre-charge voltage and the battery pack temperature.

[0211] In one possible implementation, the voltage determination module 502 is further used to: determine the predicted pre-charge voltage as the actual voltage of the battery pack when the pre-charge time is less than or equal to a first preset time; determine the target voltage difference between the actual voltage of the battery pack and the second voltage difference when the pre-charge time is greater than the first preset time and less than or equal to a second preset time; determine the predicted pre-charge voltage as the smaller voltage between the target voltage difference and the maximum voltage limit of the charging pile; and determine the predicted pre-charge voltage as the smaller voltage between the actual voltage of the battery pack and the maximum voltage limit of the charging pile when the pre-charge time is greater than the second preset time and less than or equal to a third preset time.

[0212] In one possible implementation, the voltage determination module 502 is also used to: determine a third voltage difference between the output voltage of the charging pile and the actual voltage of the battery pack when the pre-charging time is equal to the first preset time; determine a fourth voltage difference by looking up a table based on the identification of the power battery and the identification of the charging pile; and determine that the second voltage difference is the sum of the third voltage difference and the fourth voltage difference.

[0213] In one possible implementation, the voltage determination module 502 is also used to: determine the target regulation voltage according to the battery pack temperature when the battery pack temperature is less than or equal to a first preset temperature, or when the battery pack temperature is greater than or equal to a second preset temperature, and the first preset temperature is less than the second preset temperature; determine the target pre-charge voltage according to the predicted pre-charge voltage and the target regulation voltage; and determine the target pre-charge voltage to be the predicted pre-charge voltage when the battery pack temperature is greater than the first preset temperature and less than the second preset temperature.

[0214] Optionally, the device also includes a pre-charging judgment module, which is used to judge whether the power battery is pre-charged successfully based on the actual voltage of the battery pack when the pre-charging time is equal to the third preset time; if the power battery is pre-charged successfully, control the power battery to switch from the pre-charging stage to the formal charging stage; if the power battery is not pre-charged successfully, stop charging the power battery.

[0215] In one possible implementation, the pre-charge judgment module is specifically used to: determine the voltage ratio of the actual voltage of the battery pack to the nominal voltage of the battery pack; when the voltage ratio is within a preset ratio range, determine that the power battery is pre-charged successfully; when the ratio is not within the preset ratio range, determine that the power battery is not pre-charged successfully.

[0216] Figure 6 It is a structural schematic diagram of a vehicle provided in an embodiment of the present application.

[0217] For example, Figure 6As shown, the vehicle 101 includes: a memory 601 and a processor 602, wherein the memory 601 stores an executable program code 6011, and the processor 602 is used to call and execute the executable program code 6011 to perform a method for pre-charging a vehicle power battery.

[0218] In addition, an embodiment of the present application also protects a device, which may include a memory and a processor, wherein the memory stores executable program code, and the processor is used to call and execute the executable program code to perform a method for pre-charging a vehicle power battery provided in an embodiment of the present application.

[0219] In this embodiment, the device can be divided into functional modules based on the above-described method examples. For example, each functional module can be mapped to a specific functional module, or two or more functions can be integrated into a single processing module. The integrated module can be implemented in hardware. It should be noted that the module division in this embodiment is illustrative and represents only a logical functional division. In actual implementation, other division methods may be used.

[0220] In the case of dividing the functional modules into corresponding functional modules, the device may further include a parameter acquisition module, a voltage determination module, a charging module, etc. It should be noted that all relevant contents of the various steps involved in the above method embodiment can be referred to the functional description of the corresponding functional modules and will not be repeated here.

[0221] It should be understood that the device provided in this embodiment is used to execute the above-mentioned method for pre-charging a vehicle power battery, and thus can achieve the same effect as the above-mentioned implementation method.

[0222] In the case of an integrated unit, the device may include a processing module and a storage module. When the device is used in a vehicle, the processing module may be used to control and manage the vehicle's movements, while the storage module may be used to support the vehicle's execution of relevant program codes.

[0223] The processing module may be a processor or controller that implements or executes the various exemplary logic blocks, modules, and circuits described in conjunction with the present disclosure. The processor may also be a combination that implements computing functions, such as a combination of one or more microprocessors, a combination of a digital signal processing (DSP) and a microprocessor, and the storage module may be a memory.

[0224] In addition, the device provided in the embodiments of the present application can specifically be a chip, component or module, and the chip may include a connected processor and memory; wherein the memory is used to store instructions, and when the processor calls and executes the instructions, the chip can execute a vehicle power battery pre-charging method provided in the above embodiment.

[0225] This embodiment also provides a computer-readable storage medium, which stores computer program code. When the computer program code runs on a computer, the computer executes the above-mentioned related method steps to implement a vehicle power battery pre-charging method provided in the above embodiment.

[0226] This embodiment also provides a computer program product. When the computer program product is run on a computer, it enables the computer to execute the above-mentioned related steps to implement a vehicle power battery pre-charging method provided in the above embodiment.

[0227] Among them, the device, computer-readable storage medium, computer program product or chip provided in this embodiment are all used to execute the corresponding methods provided above. Therefore, the beneficial effects that can be achieved can refer to the beneficial effects in the corresponding methods provided above, and will not be repeated here.

[0228] Through the description of the above implementation methods, technical personnel in the relevant field can understand that for the convenience and simplicity of description, only the division of the above-mentioned functional modules is used as an example. In actual applications, the above-mentioned functions can be distributed and completed by different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above.

[0229] In the embodiments provided in this 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 merely schematic. For example, the division of modules or units is only a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another device, 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.

[0230] The above content is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A method for precharging a vehicle power battery, characterized in that: The method comprises: When the power battery is in the pre-charging stage, obtaining the pre-charging duration of the power battery and the operating parameters of the battery pack of the power battery, where the operating parameters of the battery pack are used to indicate the operating status of the battery pack of the power battery; Determining a target pre-charge voltage according to the pre-charge time and the battery pack operating parameters, wherein a difference between the target pre-charge voltage and the actual voltage of the battery pack is less than or equal to a first voltage difference; Sending the target pre-charge voltage to a charging pile so that the charging pile charges the power battery at the target pre-charge voltage; The battery pack operating parameters include the actual voltage of the battery pack, and determining the target pre-charge voltage according to the pre-charge time and the battery pack operating parameters includes determining a predicted pre-charge voltage according to the pre-charge time and the actual voltage of the battery pack; specifically including: When the pre-charge duration is less than or equal to a first preset duration, determining the predicted pre-charge voltage as the actual voltage of the battery pack; When the pre-charge duration is greater than the first preset duration and less than or equal to the second preset duration, determining a target voltage difference between the actual voltage of the battery pack and the second voltage difference; and determining the predicted pre-charge voltage to be the smaller voltage between the target voltage difference and the maximum voltage limit of the charging pile; When the pre-charge time is greater than the second preset time and less than or equal to the third preset time, the predicted pre-charge voltage is determined to be the smaller voltage between the actual voltage of the battery pack and the maximum voltage limit of the charging pile.

2. The method according to claim 1, characterized in that The battery pack operating parameters further include a battery pack temperature. Determining a target pre-charge voltage according to the pre-charge duration and the battery pack operating parameters includes: The target pre-charge voltage is determined according to the predicted pre-charge voltage and the battery pack temperature.

3. The method according to claim 1, characterized in that The step of determining the second voltage difference includes: When the pre-charging time is equal to the first preset time, determining a third voltage difference between the output voltage of the charging pile and the actual voltage of the battery pack; Determine a fourth voltage difference by looking up a table according to the identification of the power battery and the identification of the charging pile; The second voltage difference is determined to be the sum of the third voltage difference and the fourth voltage difference.

4. The method according to claim 2, characterized in that The determining the target pre-charge voltage according to the predicted pre-charge voltage and the battery pack temperature includes: determining a target regulation voltage according to the battery pack temperature when the battery pack temperature is less than or equal to a first preset temperature or when the battery pack temperature is greater than or equal to a second preset temperature, the first preset temperature being less than the second preset temperature; and determining the target pre-charge voltage according to the predicted pre-charge voltage and the target regulation voltage; When the battery pack temperature is greater than the first preset temperature and less than the second preset temperature, the target pre-charge voltage is determined to be the predicted pre-charge voltage.

5. The method according to claim 1, wherein The method further comprises: When the pre-charging time is equal to the third preset time, judging whether the power battery is pre-charged successfully according to the actual voltage of the battery pack; If the pre-charging of the power battery is successful, controlling the power battery to switch from the pre-charging stage to the main charging stage; If the power battery is not pre-charged successfully, charging of the power battery is stopped.

6. The method according to claim 5, characterized in that The determining, based on the actual voltage of the battery pack, whether the power battery is pre-charged successfully includes: Determining a voltage ratio of the actual battery pack voltage to the nominal battery pack voltage; When the voltage ratio is within a preset ratio range, determining that the power battery pre-charging is successful; If the ratio is not within the preset ratio range, it is determined that the power battery is not pre-charged successfully.

7. A vehicle power battery pre-charging device, characterized in that: The device comprises: a parameter acquisition module, configured to acquire, when the power battery is in the pre-charging stage, a pre-charging duration of the power battery and operating parameters of a battery pack of the power battery, wherein the operating parameters of the battery pack are used to indicate an operating state of the battery pack of the power battery; a voltage determination module, configured to determine a target pre-charge voltage according to the pre-charge duration and the operating parameters of the battery pack, wherein the difference between the target pre-charge voltage and the actual voltage of the battery pack is less than or equal to a first voltage difference; a charging module, configured to send the target pre-charge voltage to a charging pile, so that the charging pile charges the power battery at the target pre-charge voltage; The battery pack operating parameters include the actual battery pack voltage, and the voltage determination module is used to determine the target pre-charge voltage according to the pre-charge time and the battery pack operating parameters, including determining a predicted pre-charge voltage according to the pre-charge time and the actual battery pack voltage; specifically used to: When the pre-charge duration is less than or equal to a first preset duration, determining the predicted pre-charge voltage as the actual voltage of the battery pack; When the pre-charge duration is greater than the first preset duration and less than or equal to the second preset duration, determining a target voltage difference between the actual voltage of the battery pack and the second voltage difference; and determining the predicted pre-charge voltage to be the smaller voltage between the target voltage difference and the maximum voltage limit of the charging pile; When the pre-charge time is greater than the second preset time and less than or equal to the third preset time, the predicted pre-charge voltage is determined to be the smaller voltage between the actual voltage of the battery pack and the maximum voltage limit of the charging pile.

8. A vehicle, characterized in that: The vehicle comprises: a memory for storing executable program code; A processor is configured to call and run the executable program code from the memory, so that the vehicle executes the method according to any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program, and when the computer program is executed, the method according to any one of claims 1 to 6 is implemented.

Images