Parallel battery pack charging control method, battery management system and aircraft

Abstract

The application discloses a parallel battery pack charging control method, a battery management system and an aircraft, and relates to the technical field of charging control. The parallel battery pack charging control method comprises the following steps: obtaining sampling charging currents of each battery pack; determining current distribution ratios of the sampling charging currents compared with a total charging current; the total charging current is the sum of the sampling charging currents of each battery pack; and determining a total charging request current meeting an anti-overcurrent condition based on at least the current distribution ratios of each battery pack and a maximum allowed charging current. The application effectively avoids the risk of thermal runaway and guarantees charging safety while approaching the theoretical limit value as much as possible.

Description

Technical Field

[0001] This application relates to the field of charging control technology, and in particular to a parallel battery pack charging control method, a battery management system, and an aircraft. Background Technology

[0002] With the stringent demands for fast charging from new energy vehicles, eVTOL (electric vertical take-off and landing) aircraft, and electric ships, the traditional single-pack constant current-constant voltage (CC-CV) charging strategy is no longer sufficient to handle complex operating conditions. Multi-pack parallel charging technology has become a better choice. However, due to the discreteness of cell manufacturing processes, variations in ambient temperature gradients, and differences in the degree of cycle aging, the internal resistance of each battery pack exhibits dynamic nonlinear characteristics. This leads to a non-uniform distribution of shunt current in each battery pack during charging, resulting in the risk of thermal runaway. Summary of the Invention

[0003] The main objective of this application is to provide a parallel battery pack charging control method, a battery management system, and an aircraft, aiming to solve the technical problem of thermal runaway risk when charging multiple battery packs in parallel.

[0004] To achieve the above objectives, this application proposes a parallel battery pack charging control method, which includes:

[0005] Obtain the sampled charging current of each battery pack;

[0006] Determine the current allocation ratio of each sampled charging current to the total charging current; the total charging current is the sum of the sampled charging currents of each battery pack.

[0007] Based at least on the current distribution ratio of each battery pack and the maximum allowable charging current, the total charging request current that meets the overcurrent protection conditions is determined.

[0008] In one embodiment, determining the current allocation ratio of each sampled charging current to the total charging current includes:

[0009] Determine the current allocation ratio of each sampled charging current relative to the total charging current;

[0010] For each battery pack, update the current allocation ratio based on the current current allocation ratio.

[0011] In one embodiment, for each battery pack, the current allocation ratio is updated based on the current current allocation ratio, including:

[0012] Determine whether the current battery state of the parallel battery pack meets the allocation ratio update conditions;

[0013] If the conditions for updating the allocation ratio are met, the current allocation ratio for each battery pack is updated based on the current current allocation ratio.

[0014] In one embodiment, determining whether the current battery state of the parallel battery pack meets the allocation ratio update condition includes:

[0015] Determine the changes in the current distribution ratio of each battery pack based on the current current distribution ratio;

[0016] Based at least on the changes in the current distribution ratio of some battery packs, determine whether the current battery state of the parallel battery pack meets the distribution ratio update conditions.

[0017] In one embodiment, the change in current distribution ratio is the rate of change of current distribution ratio;

[0018] Based at least on the changes in the current distribution ratio of some battery packs, determine whether the current battery state of the parallel battery packs meets the distribution ratio update conditions, including:

[0019] If the rate of change of at least one current distribution ratio is greater than a preset change threshold, the current battery state of the parallel battery pack is determined to meet the current distribution ratio update condition.

[0020] If all changes in the current distribution ratio are less than or equal to the preset change threshold, it is determined that the current battery state of the parallel battery pack does not meet the current distribution ratio update condition.

[0021] In one embodiment, the total charging request current that satisfies the overcurrent protection condition is determined at least based on the current allocation ratio of each battery pack and the maximum allowable charging current, including:

[0022] For each battery pack, based on the corresponding maximum allowable charging current and current allocation ratio, determine the predicted total charging request current value that meets the overcurrent protection conditions;

[0023] The minimum value among all predicted total charging request currents is determined as the total charging request current.

[0024] In one embodiment, after determining the minimum value among all predicted total charging request currents as the total charging request current, the method further includes:

[0025] Determine the current feedback information for each battery pack;

[0026] Closed-loop control of the total charging request current is performed based on at least some current feedback information.

[0027] In one embodiment, determining the current feedback information of each battery pack includes: for each battery pack, using the current margin of the battery pack as the current feedback information, wherein the current margin is the value of the maximum allowable charging current corresponding to the battery pack minus the corresponding sampled charging current.

[0028] And / or,

[0029] Closed-loop control of the total charging request current is performed based on feedback information from various current sources, including:

[0030] Closed-loop control of the total charging request current is performed based on the minimum value among all current feedback information.

[0031] In one embodiment, before obtaining the sampled charging current of each battery pack, the method further includes:

[0032] The parallel battery packs are charged when the voltage difference between all battery packs is less than or equal to a preset risk threshold.

[0033] In addition, to achieve the above objectives, this application also proposes a battery management system, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor. The computer program is configured to implement the steps of the parallel battery pack charging control method described above.

[0034] Furthermore, to achieve the above objectives, this application also proposes an aircraft comprising:

[0035] The main body of the aircraft has a charging interface;

[0036] Parallel battery packs are installed on the main body of the aircraft; and

[0037] As mentioned above, the battery management system is located on the main body of the aircraft. The battery management system is connected to the parallel battery pack and is suitable for connection to charging equipment via a charging interface.

[0038] One or more technical solutions proposed in this application have at least the following technical effects:

[0039] Compared to the ideal current sharing assumption among battery packs in related technologies, this application determines the current distribution ratio of the sampled charging current of each battery pack to the total charging current during the charging process. The current distribution ratio can reflect the spatiotemporal distortion of current caused by the dynamic nonlinear time-varying characteristics of the internal resistance between battery packs in the short time domain. That is, it can dynamically identify the dynamic internal resistance shift between battery packs caused by temperature gradient, SOC dispersion and aging differences during the actual parallel charging process in the short time domain to a certain extent. Thus, based on the current distribution ratio of each battery pack, the total charging request current that meets the overcurrent protection condition in the short time domain can be predicted. In this way, the overcurrent risk can be effectively avoided while getting as close as possible to the theoretical limit value, which can both ensure charging safety and improve timeliness. Attached Figure Description

[0040] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0041] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 This is a schematic diagram of the architecture of a multi-battery parallel charging system involved in this application;

[0043] Figure 2 This is a flowchart illustrating the first embodiment of the parallel battery pack charging control method of this application.

[0044] Figure 3 This is a flowchart illustrating the second embodiment of the parallel battery pack charging control method of this application.

[0045] Figure 4 This is a flowchart illustrating the third embodiment of the parallel battery pack charging control method of this application.

[0046] Figure 5 A simplified flowchart illustrating a charging method for a dual-battery-pack parallel system;

[0047] Figure 6 This is a schematic diagram of the battery management system involved in the embodiments of this application.

[0048] The purpose, features, and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0049] It should be understood that the specific embodiments described herein are merely illustrative of the technical solutions of this application and are not intended to limit this application.

[0050] To better understand the technical solution of this application, a detailed description will be provided below in conjunction with the accompanying drawings and specific implementation methods.

[0051] In parallel multi-battery pack charging systems, the total charging current request algorithm has structural flaws. Specifically, related technologies are based on the ideal current sharing assumption, that is, the current is evenly distributed among the battery packs, or the related technologies assume that the current distribution ratio is fixed. Therefore, in the actual calculation, the total charging current request is generated based on the nominal request current obtained by looking up the table of individual battery packs, and arithmetic superposition rules such as summation method or extreme value mapping are used.

[0052] However, in actual parallel circuits, due to the discreteness of cell manufacturing processes, variations in ambient temperature gradients, and differences in the degree of cyclic aging, the internal resistance of each battery pack exhibits dynamic nonlinear characteristics, resulting in a non-uniform distribution of the actual current shunting among the battery packs during charging. This leads to at least two typical inefficiency scenarios: 1) Overcurrent risk under equal requests—when the actual current carried by the low-resistance branch exceeds its safety threshold, the system is forced to trigger global power reduction protection, causing all battery packs to enter a conservative charging mode; 2) Double deviation under differential requests—even if the total charging current request value is adjusted to the extreme value, the actual current shunting will still cause at least some of the battery packs to simultaneously deviate from their optimal efficiency range. Moreover, the systemic charging efficiency loss caused by this dynamic imbalance of current shunting exhibits an exponential worsening trend when the battery pack states differ significantly, severely slowing down the charging rate.

[0053] To address this, this application provides a solution that dynamically evaluates the current distribution ratio in a multi-battery-pack parallel system by sampling the charging current of each battery pack. Compared to the ideal current sharing assumption or the assumption of a fixed distribution ratio, this solution determines the current distribution ratio of the sampling charging current of each battery pack relative to the total charging current during the charging process. The current distribution ratio can reflect the spatiotemporal distortion of current caused by the dynamic nonlinear time-varying characteristics of the internal resistance between battery packs in the short time domain. In other words, it can dynamically identify, to a certain extent, the dynamic internal resistance shift between battery packs caused by temperature gradients, state of charge (SOC) dispersion, and aging differences during the actual parallel charging process in the short time domain. Thus, based at least on the current distribution ratio of each battery pack, the total charging request current that meets the overcurrent protection condition in the short time domain can be predicted, thereby effectively avoiding overcurrent risks while approximating the theoretical limit value as closely as possible.

[0054] The technical solution of this application and how it solves the above-mentioned technical problems will be described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will be described below with reference to the accompanying drawings.

[0055] The solutions provided in this application can be applied to charging scenarios with parallel battery packs, including but not limited to charging scenarios for new energy vehicles, eVTOL and electric ships, charging and energy storage scenarios in energy storage power stations, and charging scenarios for various electronic devices or industrial equipment with parallel battery packs. To better understand the solutions provided in this application, a specific application scenario will be used as an example below.

[0056] In this application scenario, please refer to Figure 1 , Figure 1A multi-battery parallel charging system is provided. The architecture of the multi-battery parallel charging system includes parallel battery packs, charging equipment, and a battery management system (BMS).

[0057] The parallel battery pack is electrically connected to the charging equipment. In this embodiment, the charging equipment is a charging pile. Both the parallel battery pack and the charging equipment are communicatively connected to the BMS. The parallel battery pack includes multiple battery packs connected in parallel, and each branch of the battery pack includes a relay and a current sensor. The BMS controls the relays of each battery pack's branch to close and outputs a total charging request current to the charging equipment. Upon receiving the total charging request current, the charging equipment outputs charging current to the parallel battery pack.

[0058] It is understood that the above is merely an example, and this embodiment is not intended to be limiting. Furthermore, the following description uses a parallel battery pack as an example of a dual-battery pack.

[0059] Based on this, embodiments of this application provide a parallel battery pack charging control method, referring to... Figure 2 , Figure 2 This is a flowchart illustrating the first embodiment of the parallel battery pack charging control method of this application.

[0060] In this embodiment, the parallel battery pack charging control method includes:

[0061] Step S10: Obtain the sampled charging current of each battery pack.

[0062] Step S20: Determine the current allocation ratio of each sampled charging current to the actual total charging current.

[0063] The total charging current is the sum of the sampled charging currents of each battery pack.

[0064] It should be noted that the executing entity in this embodiment can be a computing service device with data processing, network communication, and program execution functions, such as a tablet computer, personal computer, or mobile phone, or an electronic device or BMS capable of performing the above functions. The following description uses a BMS as an example to illustrate this embodiment and the subsequent embodiments.

[0065] During charging, the current sensor continuously monitors the charging current of its branch, thereby obtaining the sampled charging current. It should be noted that in this embodiment, the BMS can execute step S10 in real-time to obtain the sampled charging current, or the BMS can execute step S10 according to a preset sampling period. Sampling in each preset sampling period can roughly reflect the spatiotemporal distortion of current caused by the dynamic nonlinear time-varying characteristics of the internal resistance between battery packs within the short time domain of the preset sampling period. For example, the preset sampling period can be from milliseconds to seconds, such as configurable to 100ms.

[0066] Understandably, current sensors experience sampling noise during actual operation due to various types of noise, including internal sensor noise, external interference from the sensor's environment, and power supply noise, which degrades the quality of the measurement signal. Therefore, it is necessary to suppress the sensor noise of the current sensor. In one specific embodiment, the current sensor sends the collected sampled values ​​to the BMS in real time, and the BMS obtains the sampled value sequence accordingly. A moving average filter is applied to a preset number of consecutive sampled values ​​in the sampled value sequence, and the average of the most recent preset number of sampled values ​​is used as the sampling charging current at the current moment or in the current sampling period, thereby suppressing noise. The filtering condition for the moving average filter is that the fluctuation of the sampled value is less than a preset threshold. For example, taking sampling according to a preset sampling period, the preset number is 10, and the preset threshold is 10%. Therefore, in this specific embodiment, the sampling charging current can be expressed as:

[0067] ;

[0068] in, Let k be the sampled charging current of the i-th battery pack in the current sampling period, where k is a positive integer from 1 to 10, and when k ranges from 1 to 10, This represents the sampled values ​​of the i-th battery pack over the most recent 10 sampling periods. In this specific embodiment, a moving average filter is used to eliminate instantaneous noise in the sampled values. Of course, this embodiment can also use first-order lag filtering or a combination of multiple filtering methods to suppress noise; this embodiment is not limited in this regard.

[0069] After obtaining the sampled charging current of each battery pack, the total charging current of the parallel battery packs can be obtained, which is the sum of all sampled charging currents. Having obtained the sampled charging current of each battery pack and the total charging current, the current distribution ratio of each sampled charging current to the total charging current can be calculated. ;

[0070] in, This represents the current allocation ratio of the i-th battery pack in the current sampling period; This is the total charging current. Let be the sampled charging current of the j-th battery pack in the current sampling period, and n be the total number of battery packs. The value of j is a positive integer from 1 to n. Understandably, in a dual-parallel battery pack configuration, n=2.

[0071] As can be seen, after calculating the current distribution ratio, the actual battery distribution in the parallel battery pack can be known, rather than calculating the total charging request batteries based on the ideal current sharing assumption or the fixed distribution ratio assumption.

[0072] In this embodiment, the BMS may have a preset storage area for storing the current allocation ratio of each battery pack. The total charging request current will then be calculated by extracting the current allocation ratio value from this preset storage area. It is worth noting that changes in battery internal resistance are typically more pronounced at the beginning and end of charging, while the changes are relatively smaller in the intermediate stages. Therefore, in some specific implementations, the current allocation ratio can be updated in stages; that is, different update strategies are used at the beginning, middle, and end of charging to update the current allocation ratio in the preset storage area using the calculated current allocation ratio.

[0073] Alternatively, to investigate more precisely the spatiotemporal distortion of current caused by the dynamic nonlinear time-varying characteristics of internal resistance in the short time domain, in some other specific embodiments, step S20 specifically includes steps S21 to S22:

[0074] Step S21: Determine the current allocation ratio of each sampled charging current relative to the total charging current.

[0075] Step S22: For each battery pack, update the current allocation ratio based on the current current allocation ratio.

[0076] Specifically, the BMS also has a temporary storage area for storing the current current allocation ratio. When the current sensor collects and samples the charging current in real time, the current current allocation ratio is the current allocation ratio calculated in real time. When the current sensor collects and samples the charging current according to a preset sampling period, the current current allocation ratio is the current allocation ratio calculated for the current sampling period. At this time, the BMS continuously calculates the current current allocation ratio and continuously updates the current allocation ratio in the preset storage area accordingly.

[0077] It is easy to see that this specific implementation method updates the current allocation ratio based on the current allocation ratio, thereby dynamically tracking the dynamic internal resistance shift between battery packs caused by temperature gradient, state of charge (SOC) dispersion and aging differences during the actual parallel charging process in the short time domain, so as to improve the processing accuracy.

[0078] Furthermore, it is understandable that the current allocation ratio is intended to reflect, to some extent, the spatiotemporal distortion of current caused by the dynamic nonlinear time-varying characteristics of the internal resistance between battery packs. That is, it can reflect, to some extent, the dynamic internal resistance shift between battery packs caused by temperature gradients, SOC dispersion, and aging differences during actual parallel charging. However, due to the dynamic nonlinear time-varying characteristics of the battery pack internal resistance, it is always changing. If the current allocation ratio required for calculating the total charging request current is always updated in real time based on this, it will increase the pre-calculation cost of the subsequent total charging request current and decrease the calculation rate of the total charging request current. Therefore, in some specific embodiments, step S22 specifically includes steps S221 to S222:

[0079] Step S221: Determine whether the current battery state of the parallel battery pack meets the allocation ratio update condition.

[0080] Step S222: If the allocation ratio update conditions are met, update the current allocation ratio for each battery pack based on the current current allocation ratio.

[0081] Specifically, whether the current battery state meets the allocation ratio update condition reflects whether changes in dynamic internal resistance offset have significantly affected the current distribution between battery packs. If the current distribution between battery packs is significantly affected, the current allocation ratio needs to be updated. If the current distribution between battery packs is not significantly affected, the current allocation ratio does not need to be updated.

[0082] As an alternative, the BMS can determine whether the current battery state meets the allocation ratio update conditions by sampling whether there are sudden changes in the charging current. For example, if a sudden change occurs in the sampled battery current, it can be assumed that the change in internal resistance offset has significantly affected the current allocation between battery packs.

[0083] Alternatively, as another option, step S221 specifically includes steps S2211 to S2212:

[0084] Step S2211: Determine the change in the current allocation ratio of each battery pack based on the current current allocation ratio;

[0085] Step S2212: Based at least on the changes in the current distribution ratio of some battery packs, determine whether the current battery state of the parallel battery pack meets the distribution ratio update conditions.

[0086] Specifically, taking a preset sampling period as an example, each sampling charging current is obtained in the current sampling period, and the change in current allocation ratio is the change in the current current allocation ratio of the same battery pack in the current sampling period compared to the current allocation ratio in the previous sampling period.

[0087] The change in current allocation ratio can be the difference between the current allocation ratio and the current allocation ratio in the previous sampling period. Alternatively, the change in current allocation ratio can also be the rate of change of the current allocation ratio. Specifically: ;

[0088] in, Let be the rate of change of the current distribution ratio of the i-th battery pack in the current sampling period; Let be the current allocation ratio of the i-th battery pack in the previous sampling period. Let represent the current current allocation ratio of the i-th battery pack in the current sampling period. Understandably, compared to the difference in change, the rate of change of the current allocation ratio can more accurately reflect the changing excitation conditions. Therefore, the following discussion will focus on the change in the current allocation ratio, which can also be described as the rate of change of the current allocation ratio.

[0089] When the change in current allocation ratio is small, it reflects that the change in dynamic internal resistance offset is small and has little impact on the current allocation between battery packs. Therefore, there is no need to update the current allocation ratio in the preset storage area; the current allocation ratio from the previous sampling period is used as the current allocation ratio for the current sampling period, instead of the currently calculated current allocation ratio. Thus, the current current allocation ratio in the temporary storage area can be deleted. However, when the change in current allocation ratio is large, the change in dynamic internal resistance offset significantly affects the current allocation between battery packs. Therefore, it is necessary to use the currently calculated current allocation ratio, storing the current current allocation ratio from the temporary storage area into the preset storage area, thereby updating the current allocation ratio.

[0090] It is worth noting that, since the battery packs are connected in parallel, the charging current will naturally distribute according to characteristics such as internal resistance. Therefore, a significant change in the current distribution ratio of any one battery pack will affect the current distribution among all battery packs. Thus, in this specific embodiment, the determination is not limited to the change in the current distribution ratio of all battery packs; it can also be based on the change in the current distribution ratio of a subset of battery packs. For example, it could be based on the change in the current distribution ratio of all battery packs... The system determines the percentage of changes exceeding a preset threshold. If the percentage exceeds the threshold, all battery packs are updated. If the percentage is less than the set threshold, then the data for all battery packs will not be updated. .

[0091] Alternatively, when the BMS executes step S2212, it specifically performs the following: if at least one current allocation ratio change rate is greater than a preset change threshold, it determines that the current battery state of the parallel battery pack meets the current allocation ratio update condition. If all current allocation ratio change rates are less than or equal to the preset change threshold, it determines that the current battery state of the parallel battery pack does not meet the current allocation ratio update condition.

[0092] Specifically, let's take a preset change threshold of 3% as an example. If any... If the percentage is greater than 3%, then update all battery packs. , that is to say = If all ≤3%, then keep all battery packs Unchanged, that is Discard the results calculated in the current sampling period ,and = It is not difficult to see whether there exists any Using >3% as the judgment condition can balance the dynamic adaptation to changes in battery pack status and reduce the amount of calculation.

[0093] Step S30: Determine the total charging request current that meets the overcurrent protection conditions, based at least on the current allocation ratio of each battery pack and the maximum allowable charging current.

[0094] Understandably, during the charging process, the BMS will consult the preset charging power mapping table for each battery pack based on the real-time status of each battery pack, including but not limited to SOC, temperature, individual cell voltage, and health status, to calculate the maximum allowable charging current of that battery pack under the current state. This is the safe upper limit for the battery pack in its current state.

[0095] Since the battery packs are connected in parallel, the charging current will naturally be distributed according to characteristics such as internal resistance. To ensure the safety of all battery packs, the BMS must adopt the most conservative strategy, that is, calculate the most conservative total charging request current based on the maximum allowable charging current of each battery pack. Because the current distribution ratio is known, this embodiment essentially dynamically identifies the internal resistance differences of each battery pack in the short time domain, which is equivalent to constructing a short-time domain observation model. This allows for more refined prediction of the total charging request current, improving the charging rate of the multi-battery pack parallel system while meeting safety requirements through more refined charging request current management.

[0096] In one specific implementation, when the BMS executes step S30, it specifically executes steps S31 to S32:

[0097] Step S31: For each battery pack, based on the corresponding maximum allowable charging current and current allocation ratio, determine the predicted total charging request current value that meets the overcurrent protection condition.

[0098] Step S32: Determine the minimum value among all predicted total charging request current values ​​as the total charging request current.

[0099] Specifically, in this embodiment, since the current distribution ratios are known, there are at least two constraints in the BMS:

[0100] (1) The current of each battery pack does not exceed its maximum allowable value. To avoid overcurrent, the requested current for each battery pack must meet the following requirements:

[0101] ;

[0102] in, For the total charging request current, The requested current allocated to the estimated i-th battery pack.

[0103] (2) The total charging request current must also meet the constraints of all battery packs simultaneously:

[0104] ;

[0105] Therefore, in this specific embodiment, for each battery pack, the predicted total charging request current value corresponding to meeting the overcurrent protection condition is determined by using the corresponding maximum allowable charging current and current allocation ratio. To ensure the safety of all battery packs, the BMS must adopt the most conservative strategy; therefore, the minimum value among all predicted total charging request current values ​​is determined as the total charging request current.

[0106] It is easy to see that, compared with the ideal current sharing assumption among battery packs in related technologies, this embodiment determines the current distribution ratio of the sampled charging current of each battery pack to the actual total charging current during the charging process. The current distribution ratio can reflect the spatiotemporal distortion of current caused by the dynamic nonlinear time-varying characteristics of the internal resistance between battery packs in the short time domain. That is, it can dynamically identify the dynamic internal resistance shift between battery packs caused by temperature gradient, SOC dispersion and aging differences during the actual parallel charging process in the short time domain to a certain extent. Thus, based on at least part of the current distribution ratio, the total charging request current that meets the overcurrent protection condition in the short time domain can be predicted, thereby effectively avoiding the risk of overcurrent while getting as close as possible to the theoretical limit value.

[0107] Furthermore, during actual charging, the actual output current of the charging equipment and the total charging request current issued by the BMS exhibit dynamic deviations due to factors such as cable impedance fluctuations and equipment response accuracy. Therefore, based on the above embodiments, a second embodiment of this application is proposed. In this second embodiment, content that is the same as or similar to the first embodiment described above can be referred to the above description and will not be repeated hereafter. Based on this, please refer to... Figure 3 In this embodiment, after step S30, the method further includes:

[0108] Step S40: Determine the current feedback information for each battery pack.

[0109] Step S50: Perform closed-loop control of the total charging request current based on at least some current feedback information.

[0110] It should be noted that in this embodiment, after the total charging request current is sent to the charging device, the current can be detected again by a current sensor (the sampled charging current collected in the next sampling period), thereby determining the current feedback information of the battery pack, and then performing closed-loop control accordingly. That is, the current allocation ratio determination process and the closed-loop control process are performed separately.

[0111] Alternatively, step S40 may include step S41: For each battery pack, the current margin of the battery pack is used as current feedback information. The current margin is the value of the maximum allowable charging current corresponding to the battery pack minus the corresponding sampled charging current.

[0112] Specifically, during the current sampling period, after obtaining the sampled charging current, the BMS can calculate the difference between the sampled charging current of each battery pack and the corresponding maximum allowable charging current of each battery pack, thus determining the current margin of each battery pack. Therefore, in this embodiment, closed-loop control can also be performed before sending the total charging request current to the charging equipment, that is, integrating the current allocation ratio determination process and the closed-loop control process together.

[0113] Furthermore, as mentioned before, to ensure the safety of all battery packs, the BMS must employ the most conservative strategy for closed-loop control. Therefore, when the BMS executes step S50, it specifically performs closed-loop control on the total charging request current based on the minimum value among all current feedback information. Additionally, closed-loop control can include, but is not limited to, proportional-integral (PI) control and proportional-integral-derivative (PI-DE) control. The following explanation uses a proportional-integral controller as an example:

[0114] The minimum current margin among all battery packs is taken as the input of the proportional-integral controller. This can be expressed as: ;

[0115] in, The input is used as the input to the proportional-integral controller, which calculates the requested current fine-tuning amount. Finally, the total charging request current is adjusted according to the requested current fine-tuning amount, and the adjusted total charging request current is sent to the charging equipment. This effectively compensates for the systematic deviation caused by line loss and equipment error, thereby improving the overall charging stability and rate consistency of the multi-battery pack parallel system.

[0116] Furthermore, considering that when the current margin is small, if the integral action is too strong, due to its cumulative effect, even if the deviation is small, the proportional-integral controller output will continue to fine-tune. However, the system has inertia, and this fine-tuning can easily cause the actual value to fluctuate around the target value (oscillation). For systems like parallel battery packs that require stable operation, such oscillation is unacceptable. Therefore, closed-loop correction via the proportional-integral controller should only be performed when the current margin is large to quickly eliminate major deviations and prevent battery overcharging / over-discharging. In addition, the primary task of the BMS is safety and stability. For battery pack charging, temporary small deviations are acceptable; ensuring that the system does not oscillate or overshoot is the key priority.

[0117] Therefore, proportional-integral control can be selectively performed based on the current margin. In one specific embodiment, the BMS executes step S50 when the minimum value is less than 0, or when the minimum value is greater than or equal to a preset trigger threshold. Correspondingly, when the minimum value is greater than or equal to 0 and less than the preset trigger threshold, the total charging request current is sent to the charging device.

[0118] Specifically, taking a preset trigger threshold of 2A as an example, when or When established, a proportional-integral controller is used to fine-tune the total charging request current.

[0119] In one example, ;

[0120] in, This is the request value sent by the BMS to the charging device; here it is the adjusted total charging request current. The proportional coefficient of the proportional-integral controller. The integral coefficient of the proportional-integral controller; The current deviation for the current sampling period. This represents the current deviation from the previous sampling period.

[0121] And in and If neither condition is met, there is no need to fine-tune the total charging request current. In this case, the BMS directly sends the total charging request current to the charging device.

[0122] It is easy to see that this embodiment addresses the dynamic deviation between the actual output current of the charging pile and the requested value (mainly caused by cable impedance fluctuations and equipment response accuracy). It establishes a closed-loop correction control based on current feedback information to effectively compensate for the systematic deviation caused by line losses and equipment errors, thereby improving the overall charging stability and rate consistency of the multi-battery pack parallel system.

[0123] Furthermore, in complex high-power multi-battery pack parallel charging scenarios, the initial voltage deviation between parallel battery packs can reach tens of volts. Directly closing the charging relay may trigger a circulating current surge, leading to damage to electrical components or the risk of thermal runaway. Therefore, based on the above embodiments, a third embodiment of this application is proposed. In this third embodiment, content that is the same as or similar to the above embodiments can be referred to the above description, and will not be repeated hereafter. Based on this, please refer to... Figure 4 In this embodiment, before step S10, the method further includes:

[0124] Step A10: Charge the parallel battery packs when the voltage difference between all battery packs is less than the preset risk threshold.

[0125] Specifically, taking a preset risk threshold of 5V as an example, in this embodiment, at the beginning of charging, to protect the system, it is necessary to collect the voltage data of each battery pack and calculate the voltage difference U_diff between the battery packs. It is then determined whether the voltage difference U_diff is less than 5V. If so, parallel charging of the parallel battery packs is performed, that is, the relays of the branches where each battery pack is located are closed, thereby charging all battery packs simultaneously.

[0126] To facilitate judgment, the maximum value among all voltage data is used as the reference voltage data, and the corresponding battery pack is used as the reference battery pack. When the voltage difference U_diff between any battery pack and the reference battery pack is greater than or equal to 5V, that battery pack is charged individually until U_diff is less than 5V.

[0127] Of course, it's understandable that when the parallel battery pack consists of two battery packs, the battery pack with the lower voltage can be charged separately first. Once U_diff is less than 5V, the relay in the branch containing the battery pack with the higher voltage can be closed, thus charging both battery packs simultaneously. When the parallel battery pack includes three or more battery packs, the battery packs with the lower voltage can be charged sequentially until U_diff is less than 5V, and then all battery packs can be charged together.

[0128] In addition, during the individual charging process of a single battery pack, the BMS performs the following steps:

[0129] Step B10: During the standalone charging process, acquire the real-time pressure difference between the battery pack and the reference battery pack.

[0130] Step B20: Based on the real-time differential pressure query, the preset differential pressure-current mapping relationship is used to obtain the target charging rate corresponding to the real-time differential pressure.

[0131] The mapping relationship includes the positive correlation between the voltage difference and the charging rate.

[0132] Step B30: Determine the real-time charging request current of the battery pack based on the target charging rate.

[0133] Specifically, in this embodiment, the BMS determines the real-time charging request current of the battery pack based on the dynamic real-time voltage difference to avoid overcharging individual batteries. Therefore, the BMS maintains a preset voltage difference-current mapping relationship, where the voltage difference and charging rate are positively correlated. Thus, during individual charging, as the voltage difference approaches a preset risk threshold, the charging rate gradually decreases, resulting in a smaller requested current. That is, when the voltage difference is large, high-rate fast charging is used, while when the voltage difference is small, low-rate trickle charging is employed, thereby achieving a balance between goals such as fast charging, battery protection, and extended lifespan.

[0134] In addition, the battery pack has the maximum permissible charging current in its current state. This is the safe upper limit for the battery pack in its current state. Therefore, the maximum allowable charging current must also be considered during actual charging. .

[0135] In one specific implementation, when the BMS executes step B30, it specifically performs the following:

[0136] Step B31: Determine the current charging request current of the battery pack based on the maximum allowable charging current of the battery pack.

[0137] Step B32: Determine the smaller value between the current value corresponding to the target charging rate and the current charging request current as the real-time charging request current.

[0138] Specifically, the current charging request current of the i-th battery pack is calculated. , ;in, This is a limiting factor. At this point, the BMS stores the following table:

[0139]

[0140] Where C represents the charging rate.

[0141] That is, the real-time charging request current is the smaller value between the current value corresponding to the target charging rate and the current charging request current.

[0142] It is easy to see that this embodiment achieves a balance between goals such as fast charging, battery protection, and extended lifespan by introducing the maximum allowable charging current.

[0143] For example, to help understand the implementation flow of the parallel battery pack charging control method obtained by combining the above embodiments, please refer to... Figure 5 , Figure 5A simplified flowchart of a charging method for a dual-battery pack parallel system is provided, specifically:

[0144] The normal charging process of a dual-battery-pack parallel system can be divided into four stages, such as... Figure 5 As shown.

[0145] Phase 1: After the charging gun is inserted, the BMS calculates the voltage difference U_diff of the battery pack based on the high-voltage sampling value. To avoid circulating current surges caused by excessive voltage difference, when the voltage difference exceeds 10V, the BMS controls the relay of the branch containing the battery pack with the lowest total voltage to close for individual charging. During individual charging, the BMS outputs a dynamic charging request current to the charging station based on the dynamic voltage difference until the dynamic voltage difference of the battery pack is below 5V. Then, it prepares to close the second battery pack.

[0146] Phase 2: At this point, the dual-battery-pack parallel system begins parallel charging. The BMS outputs a dynamic charging request current to the charging station and determines whether any one of the battery packs is fully charged.

[0147] At this point, the current distribution coefficients of all battery packs are initialized to be equally proportional. n is the number of battery packs connected in parallel; in this example, n=2.

[0148] Initial total charging request current calculation: The maximum allowable charging current for each battery pack in the current state is obtained by referring to a table. Calculate the total charging request current: ;

[0149] In each sampling period during this phase, the BMS performs a moving average filter with a window size of 10 on the sampled values ​​of each battery pack to eliminate instantaneous noise and obtain the sampled charging current of each battery pack in the current sampling period. Calculate the current allocation ratio of each battery pack to the total charging current. .

[0150] Then calculate the current... Current allocation ratio compared to the previous sampling period relative rate of change If there exists any If the percentage is greater than 3%, then update all battery packs. , that is to say = If all ≤3%, then keep all battery packs Unchanged, meaning the result calculated in the current sampling period is discarded. ,make = .

[0151] Then according to The total charging request current is calculated.

[0152] Before sending the total charging request current to the charging device, the minimum current margin among all battery packs is taken as the input to the proportional-integral controller. ;

[0153] when or Upon initial setup, a proportional-integral controller is used to fine-tune the total charging request current. At this point, ;

[0154] And in or If none of these conditions are met, there is no need to fine-tune the total charging request current. At this time, the request value sent by the BMS to the charging device... .

[0155] Phase 3: At this point, any one battery pack is fully charged. To prevent relay damage, the BMS sends a safety request current. If the current in the charging circuit meets the requirements, the BMS controls the disconnection of the relay in the branch where the fully charged battery pack is located, starts charging a single battery pack, and determines whether the remaining battery packs are fully charged.

[0156] Phase 4: Once the remaining battery pack is fully charged, the battery management system disconnects the charging relay, ending the charging process.

[0157] In case of a charging failure or premature termination of charging during the charging process, the battery management system will disconnect the charging relays of the two battery packs when the current in the charging circuit I1+I2<10A to protect the relays.

[0158] It is evident that in parallel charging systems with multiple battery packs, such as dual-pack systems, the dynamic nonlinear time-varying characteristics of the internal resistance between battery packs (originating from differences in cell manufacturing tolerances, temperature field distribution gradients, and cyclic aging) will cause spatiotemporal distortions in the shunt current. This necessitates the construction of an intelligent charging request current decision mechanism in the charging control strategy. This mechanism must ensure that the maximum charging power of the parallel multi-pack system approaches the theoretical limit while effectively mitigating overcurrent risks, achieving a dynamic balance between charging safety and timeliness. Furthermore, there are safety hazards during the pre-charging phase of parallel multi-pack charging systems: on the one hand, the initial SOC dispersion of the parallel battery packs may cause voltage deviations of tens of volts, and directly closing the relay may trigger circulating current surges. Therefore, a dynamic current-limiting model based on real-time battery status assessment needs to be established to control the surge current at the moment of relay closure within the relay's electrical life threshold, thus meeting safety requirements.

[0159] This example proposes an algorithm for dynamically adjusting the charging request current of a multi-battery parallel system. By sampling the charging current of each battery pack, the current shunt ratio of the multi-battery pack parallel system is dynamically estimated. Under the condition of preventing overcurrent, the total charging request current is estimated. Subsequently, an incremental proportional-integral controller is used to fine-tune the total charging request current, achieving refined dynamic adjustment of the charging request current while ensuring safety and charging rate. Furthermore, this example designs a parallel charging safety strategy based on battery pack state assessment. By monitoring the state of the battery pack, the selective closing of relays is controlled to avoid circulating current surges caused by excessive initial voltage differences in the battery pack.

[0160] Therefore, compared to the single-pack and multi-pack parallel charging request current strategies in related technologies, this example achieves more refined charging request current estimation. While meeting safety requirements, it improves the charging rate of multi-pack parallel systems through more refined charging request current management. Furthermore, the charging control strategy proposed in this example adopts a modular design architecture, which can adapt to different parallel scales (two or more battery packs) by integrating battery state monitoring. It proactively eliminates the circulating current risk caused by initial voltage difference before the charging relay operates, and achieves system-level safety protection through a graded current limiting mechanism, thus balancing the strategy's versatility and safety requirements.

[0161] It should be noted that the above examples are only for understanding this application and do not constitute a limitation on the parallel battery pack charging control method of this application. Any simple modifications based on this technical concept are within the protection scope of this application.

[0162] This application provides a battery management system, which includes: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, which are executed by the at least one processor to enable the at least one processor to perform the parallel battery pack charging control method in Embodiment 1 above.

[0163] The following is for reference. Figure 6 It shows a schematic diagram of a battery management system suitable for implementing embodiments of this application. Figure 6 The battery management system shown is merely an example and should not impose any limitations on the functionality and scope of use of the embodiments of this application.

[0164] like Figure 6As shown, the battery management system may include a processing device 1001 (e.g., a central processing unit, a graphics processing unit, etc.) that can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM) 1002 or a program loaded from a storage device 1003 into a random access memory (RAM) 1004. The RAM 1004 also stores various programs and data required for the operation of the battery management system. The processing device 1001, ROM 1002, and RAM 1004 are interconnected via a bus 1005. An input / output (I / O) interface 1006 is also connected to the bus. Typically, the following systems can be connected to the I / O interface 1006: input devices 1007 including, for example, a touchscreen, touchpad, keyboard, mouse, image sensor, microphone, accelerometer, gyroscope, etc.; output devices 1008 including, for example, a liquid crystal display (LCD), speaker, vibrator, etc.; storage devices 1003 including, for example, magnetic tape, hard disk, etc.; and communication devices 1009. The communication device 1009 allows the battery management system to communicate wirelessly or wiredly with other devices to exchange data. Although the figure shows a battery management system with various systems, it should be understood that implementation or possession of all the systems shown is not required. More or fewer systems may be implemented alternatively.

[0165] Specifically, according to the embodiments disclosed in this application, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments disclosed in this application include a computer program product comprising a computer program carried on a computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via a communication device, or installed from storage device 1003, or installed from ROM 1002. When the computer program is executed by processing device 1001, it performs the functions defined in the methods of the embodiments disclosed in this application.

[0166] The battery management system provided in this application, employing the parallel battery pack charging control method in the above embodiments, can solve the technical problem of overcurrent charging that easily occurs when multiple battery packs are charged in parallel. Compared with the prior art, the beneficial effects of the battery management system provided in this application are the same as those of the parallel battery pack charging control method provided in the above embodiments, and other technical features in this battery management system are the same as those disclosed in the previous embodiment method, and will not be repeated here.

[0167] It should be understood that the various parts disclosed in this application can be implemented using hardware, software, firmware, or a combination thereof. In the description of the above embodiments, specific features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments or examples.

[0168] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0169] Furthermore, this application also provides an aircraft, comprising: an aircraft body, a parallel battery pack, and a battery management system. The aircraft body has a charging interface; the parallel battery pack is disposed on the aircraft body; the battery management system is disposed on the aircraft body, connected to the parallel battery pack, and adapted to be connected to a charging device via the charging interface. The specific structure of the battery management system refers to the above embodiments. Since this aircraft adopts all the technical solutions of all the above embodiments, it at least has all the beneficial effects brought by the technical solutions of the above embodiments, which will not be elaborated here.

[0170] The aircraft can be an eVTOL.

[0171] This application provides a computer-readable storage medium having computer-readable program instructions (i.e., a computer program) stored thereon, the computer-readable program instructions being used to execute the parallel battery pack charging control method in the above embodiments.

[0172] The computer-readable storage medium provided in this application may be, for example, a USB flash drive, but is not limited to, electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems or devices, or any combination thereof. More specific examples of computer-readable storage media may include, but are not limited to: electrical connections having one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. In this embodiment, the computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system or device. The program code contained on the computer-readable storage medium may be transmitted using any suitable medium, including but not limited to: wires, optical cables, RF (Radio Frequency), etc., or any suitable combination thereof.

[0173] The aforementioned computer-readable storage medium may be included in the battery management system; or it may exist independently and not be assembled into the battery management system.

[0174] The aforementioned computer-readable storage medium carries one or more programs that, when executed by the battery management system, cause the battery management system to: obtain the sampled charging current of each battery pack; determine the current allocation ratio of each sampled charging current to the actual total charging current; the actual total charging current is the sum of all sampled charging currents; and, based on the current allocation ratio of each battery pack and the maximum allowable charging current, determine the total charging request current that satisfies the overcurrent protection condition.

[0175] Computer program code for performing the operations of this application can be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, and C++, and conventional procedural programming languages ​​such as the "C" language or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network—including a Local Area Network (LAN) or a Wide Area Network (WAN)—or can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0176] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0177] The modules described in the embodiments of this application can be implemented in software or hardware. The names of the modules do not necessarily limit the functionality of the unit itself.

[0178] The readable storage medium provided in this application is a computer-readable storage medium that stores computer-readable program instructions (i.e., a computer program) for executing the above-described parallel battery pack charging control method. This solves the technical problem of overcurrent charging that easily occurs when multiple battery packs are charged in parallel. Compared with the prior art, the beneficial effects of the computer-readable storage medium provided in this application are the same as those of the parallel battery pack charging control method provided in the above embodiments, and will not be repeated here.

[0179] The above are only some embodiments of this application and do not limit the patent scope of this application. All equivalent structural transformations made under the technical concept of this application and using the content of this application specification and drawings, or direct / indirect applications in other related technical fields, are included in the patent protection scope of this application.

Claims

1. A parallel battery pack charging control method, characterized in that, The parallel battery pack charging control method includes: Obtain the sampled charging current of each battery pack; Determine the current allocation ratio of each of the sampled charging currents relative to the total charging current; the total charging current is the sum of the sampled charging currents of each of the battery packs; Based at least on the current allocation ratio of each of the battery packs and the maximum allowable charging current, the total charging request current that satisfies the overcurrent protection condition is determined; Determining the current allocation ratio of each sampled charging current to the total charging current includes: Determine the current allocation ratio of each of the sampled charging currents relative to the total charging current; The change in the current allocation ratio of each battery pack is determined based on the current current allocation ratio; the change in the current allocation ratio is the rate of change of the current allocation ratio. Based at least on the changes in the current distribution ratio of some of the battery packs, it is determined whether the current battery state of the parallel battery pack meets the distribution ratio update condition; If the allocation ratio update condition is met, the current allocation ratio is updated for each battery pack based on the current current allocation ratio.

2. The parallel battery pack charging control method as described in claim 1, characterized in that, The step of determining whether the current battery state of the parallel battery pack meets the allocation ratio update condition based at least on the changes in the current allocation ratio of a portion of the battery packs includes: If the rate of change of at least one of the current distribution ratios is greater than a preset change threshold, the current battery state of the parallel battery pack is determined to meet the current distribution ratio update condition. If all the current distribution ratio changes are less than or equal to the preset change threshold, it is determined that the current battery state of the parallel battery pack does not meet the current distribution ratio update condition.

3. The parallel battery pack charging control method as described in claim 1 or 2, characterized in that, The determination of the total charging request current that satisfies the overcurrent protection condition, based at least on the current allocation ratio of each of the battery packs and the maximum allowable charging current, includes: For each of the battery packs, based on the corresponding maximum allowable charging current and the current allocation ratio, the predicted total charging request current value corresponding to meeting the overcurrent protection condition is determined. The minimum value among all the predicted total charging request current values ​​is determined as the total charging request current.

4. The parallel battery pack charging control method as described in claim 3, characterized in that, After determining the minimum value among all the predicted total charging request currents as the total charging request current, the method further includes: Determine the current feedback information for each of the battery packs; The total charging request current is controlled in a closed loop based on at least part of the current feedback information.

5. The parallel battery pack charging control method as described in claim 4, characterized in that, The step of determining the current feedback information for each battery pack includes: for each battery pack, using the current margin of the battery pack as the current feedback information, wherein the current margin is the value of the maximum allowable charging current corresponding to the battery pack minus the corresponding sampled charging current; And / or, The closed-loop control of the total charging request current based on at least a portion of the current feedback information includes: The total charging request current is controlled in a closed loop based on the minimum value among all the current feedback information.

6. The parallel battery pack charging control method as described in claim 1 or 2, characterized in that, Before obtaining the sampled charging current of each battery pack, the method further includes: The parallel battery packs are charged when the voltage difference between all the battery packs is less than or equal to a preset risk threshold.

7. A battery management system, characterized in that, The battery management system includes a memory, a processor, and a computer program stored in the memory and executable on the processor, the computer program being configured to implement the steps of the parallel battery pack charging control method as described in any one of claims 1 to 6.

8. An aircraft, characterized in that, The aircraft includes: The main body of the aircraft has a charging interface; Parallel battery pack, wherein the parallel battery pack is disposed on the main body of the aircraft; and The battery management system as described in claim 7 is disposed on the aircraft body, connected to the parallel battery pack, and adapted to be connected to a charging device via the charging interface.

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