Battery multi-pack parallel system and equalization control method

Abstract

The invention provides a multi-battery-pack parallel system and a balance control method. The system comprises a main controller and N battery packs connected to a high-voltage bus in parallel, each battery pack comprises M battery cells which are sequentially connected in series, corresponding M equalization switches and a relay switch, each battery cell is connected with two ends of the corresponding equalization switch through an equalization resistor to form an equalization loop, and two ends of the M battery cells which are connected in series are respectively connected with a total voltage sampling point of the battery pack; a slave controller is arranged in each battery pack, and all the slave controllers are in signal connection with the master controller. The on-off time of an equalization switch is controlled through a passive equalization algorithm, calculation is carried out by considering the consistency between single battery cells and the consistency between battery packs, and passive equalization is continuously carried out within 24h / day; the equalization time is greatly shortened, the overall consistency of the multi-packet system is kept in an optimal state, and the maximum charging and discharging capacity of the multi-packet parallel system is released.

Description

Technical Field

[0001] This application relates to a parallel system of multiple battery packs and a method for equalization control, belonging to the field of battery pack equalization control technology. Background Technology

[0002] In high-voltage battery systems, differences in capacity, internal resistance, and self-discharge rate among individual cells lead to increasingly poor consistency over long periods of storage or operation, significantly reducing the battery system's discharge energy. The control method to reduce these inconsistencies is called battery equalization control, which is divided into passive and active equalization control. Active equalization uses a DC-DC converter to actively transfer capacity from cells with higher voltage to those with lower capacity. The key to active equalization is designing a suitable active capacity transfer circuit. Passive equalization involves passively discharging excess cell capacity through resistors. The key to passive equalization is calculating the discharge time. Excessive discharge time or selecting the wrong cell for discharge will lead to increasingly larger inconsistencies between cells, while insufficient equalization time will not adequately improve the battery system's discharge performance.

[0003] However, in multi-pack systems, in addition to considering the consistency between individual cells, it is also necessary to consider the voltage difference between battery packs to avoid the relay melting and sticking due to the large current at the moment of relay closure caused by the voltage difference between battery packs during high voltage operation. This invention provides a balancing control method for multi-pack parallel systems, which comprehensively considers the consistency between individual cells and the consistency between battery packs in the calculation, and performs passive balancing continuously 24 hours a day; it greatly shortens the balancing time and keeps the overall consistency of the multi-pack system in an optimal state, releasing the maximum charge and discharge capacity of the multi-pack system. Summary of the Invention

[0004] In view of at least one of the above technical problems, this application provides a battery multi-pack parallel system and a balancing control method.

[0005] To solve the above-mentioned technical problems, the technical solution adopted in this application is: According to a first aspect of this application, a multi-pack battery parallel system is provided, including a main controller and N battery packs connected in parallel to a high-voltage bus. A single battery pack includes: M battery cells connected in series, M corresponding equalization switches, and M+1 equalization resistors. The two ends of the M battery cells connected in series are respectively connected to the total voltage sampling points A and B of the battery pack. Each battery cell is connected to the two ends of the corresponding equalization switch through an equalization resistor to form an equalization circuit. The total voltage sampling point A is connected to the positive terminal of the high-voltage bus, and point B is connected to the negative terminal of the high-voltage bus. A relay switch is installed between point A and the positive terminal of the high-voltage bus or between point B and the negative terminal of the high-voltage bus. Each battery pack contains a slave controller, and all slave controllers are connected to the master controller via signals.

[0006] According to a second aspect of this application, a method for equalization control of the aforementioned multi-pack battery parallel system is provided, comprising: Before the vehicle goes into hibernation, the main controller controls all the relay switches in all N battery packs to disconnect and control all the slave controllers in all N battery packs to enter hibernation, and starts to count the hibernation time. When the hibernation time reaches the first time T1, all the slave controllers in all N battery packs wake up and wake up the main controller. The controller sends the corresponding battery pack voltage UPack(n), the voltage of each cell in the battery pack UCell(m), and the remaining capacity of each cell CellSOC(m) to the main controller from each of the N battery packs; where UPack(n) represents the voltage of the nth battery pack, n=1…N; UCell(m) and CellSOC(m) represent the voltage and remaining capacity of the mth cell in the battery pack, respectively, m=1…M; The main controller (MBMU) performs packet balance determination, including: Based on all N battery pack voltages UPack(n), determine the maximum battery pack voltage UPack_Max and the minimum battery pack voltage UPack_Min; If UPack_Max - UPack_Min > UPack_Max * a, then for each battery pack, the equalization time within the pack is calculated separately and sent to the corresponding slave controller within the battery pack via the CAN bus; a is a number between 0 and 1. If UPack_Max - UPack_Min ≤ UPack_Max * a, disable inter-packet equalization, set the inter-packet equalization time to 0, disconnect all equalization switches in all battery packs, control all controllers in all battery packs to enter sleep mode, and set the real-time clock wake-up time to the first time T1. After the real-time clock RTC wakes up, the inter-packet equalization judgment is performed again.

[0007] In some embodiments, the equalization time within each battery pack is calculated separately, including: Calculate the difference UPack_D(n) between the voltage UPack(n) of the nth battery pack and the minimum battery pack voltage UPack_Min. Determine the minimum cell voltage UCell_Min(n) in the nth battery pack based on the voltages of the M cells UCell(m) in the nth battery pack. Determine the minimum remaining cell capacity CellSOC_Min(n) in the nth battery pack based on the remaining capacity of the M cells CellSOC(m) in the nth battery pack. If UPack(n)-UPack_Min>UPack_Max*b and CellSOC_Min(n)>c, calculate the difference between the voltage of the m-th cell and the voltage of the smallest cell in the battery pack, UCell_D(m), and the difference between the remaining capacity of the m-th cell and the remaining capacity of the smallest cell in the battery pack, CellSOC_D(m); sort the M CellSOC_D(m) from largest to smallest and store them in the first sequence CellSOC_D_Aarry[], and store the M UCell_D(m) in the second sequence UCell_D_Aarry[] according to the cell order in the first sequence; Based on the voltage of the nth battery pack and the second sequence, determine the equalization switch that needs to be turned on in the nth battery pack and the number of switches K. Based on the battery capacity and remaining capacity of the corresponding cell, calculate the equalization time CellBall_T[k] of the K equalization switches that need to be turned on; If CellBall_T[k] > 0, turn on the corresponding equalization switch, and control the nth battery pack to enter sleep mode from the controller and set the real-time clock wake-up time to the second time T2. After the real-time clock wakes up, the equalization judgment between the packs is re-performed. If CellBall_T[k]=0, turn off the corresponding equalization switch, and control the controller in the nth battery pack to enter sleep mode and set the real-time clock wake-up time to the first time T1. After the real-time clock wakes up, the equalization judgment between the packs is re-performed.

[0008] Furthermore, in some embodiments, the number of equalization switches to be activated within the nth battery pack and the number K of switches are determined based on the voltage of the nth battery pack and the second sequence, including: S1. Count the number K of equalization switches that need to be turned on in the battery pack, and set the initial value of K to 1; S2. Calculate the equalization voltage UPack_Ball[K] based on the number of switches K and the second sequence UCell_D_Aarry[]. UPack_Ball[K] = ∑UCell_D_Aarry[k], k = 1, ..., K; S3. If UPack_Ball[K]≥UPack_D(n) and UPack_Ball(K-1)<UPack_D(n) are not satisfied, then K=K+1; S4. Repeat steps S2-S4 until UPack_Ball[K]≥UPack_D(n) and UPack_Ball(K-1)<UPack_D(n), and determine the equalization switches corresponding to the first K cells in the second sequence as the equalization switches that need to be turned on in the battery pack.

[0009] In some embodiments, the equalization control method of the battery multi-pack parallel system further includes: if UPack(n)-UPack_Min≤UPack_Max*b, turning off inter-pack equalization, setting the inter-pack equalization time to 0, disconnecting all equalization switches in the nth battery pack, controlling the controller in the nth battery pack to enter sleep mode, and setting the real-time clock wake-up time to the first time T1, and re-performing the inter-pack equalization judgment after the real-time clock wakes up.

[0010] In some embodiments, the equalization control method of the multi-pack parallel battery system further includes: if UPack(n)-UPack_Min>UPack_Max*b and CellSOC_Min(n)≤c, start inter-pack equalization, turn on all equalization switches in the nth battery pack, control the controller SBMU(n) in the nth battery pack to enter sleep mode and set the real-time clock wake-up time to the second time T2, and re-perform inter-pack equalization judgment after the real-time clock wakes up.

[0011] In some embodiments, a is 5%.

[0012] In some embodiments, b is 1%.

[0013] In some embodiments, c is 95%.

[0014] In some embodiments, the first time T1 is 2 hours; in some embodiments, the second time T2 is 1 hour.

[0015] According to a third aspect of this application, this application also provides a new energy vehicle, wherein the new energy vehicle is equipped with the above-mentioned multi-pack parallel battery system and uses the above-mentioned equalization control method for passive equalization.

[0016] The beneficial effects achieved by this application are as follows: An independent passive balancing circuit is established within each battery pack, adjusting the consistency between battery packs and between cells through external discharge via balancing resistors. Each balancing circuit has an independent balancing switch control, with the on and off times of the balancing switch controlled by a passive balancing algorithm. When the vehicle is powered off, the main controller MBMU and slave controller SBMU enter sleep mode. The slave controller SBMU begins accumulating sleep time, and wakes up the main controller MBMU when the sleep time exceeds 2 hours. After wake-up, the main controller MBMU calculates the balancing switch closing time and sends it to the slave controller SBMU. The slave controller SBMU controls the balancing switch to open and close according to the closing time sent by the main controller MBMU. This avoids the large current that could cause relay melting and sticking during high-voltage periods in multi-pack systems due to voltage differences between battery packs. The application comprehensively considers the consistency between cells in a single pack and the consistency between battery packs, performing passive balancing continuously 24 hours a day. This significantly shortens the balancing time and maintains the overall consistency of the multi-pack system at its optimal state, releasing the maximum charge and discharge capacity of the multi-pack system. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a multi-pack battery parallel system provided in an embodiment of this application; Figure 2 This is a schematic diagram illustrating the determination of the equalization enable condition for a multi-pack parallel battery system provided in an embodiment of this application. Figure 3 This is a schematic diagram of the intra-packet equalization time calculation process provided in an embodiment of this application. Detailed Implementation

[0018] The present application will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and should not be used to limit the scope of protection of the present application.

[0019] In the description of this invention, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0020] In the description of this invention, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0021] In related technologies, traditional passive equalization-based control methods aim to consider the capacity differences between battery cells, calculating the equalization time by correcting the static OCV of the cells to determine the magnitude of the capacity differences. However, this approach has the following drawbacks: it does not consider equalization control between battery packs. In multi-pack systems, in addition to considering the consistency between battery cells, it is also necessary to consider the consistency differences between battery packs to avoid large currents during high-voltage operation that could cause relays to melt and stick together when closed.

[0022] To address the issue of battery pack consistency in multi-pack parallel battery systems for new energy vehicles, this application provides a passive balancing control scheme for such systems. An independent passive balancing circuit is established within each pack, adjusting the consistency between battery packs and between cells by discharging through balancing resistors. Each balancing circuit has an independent balancing switch control, with the on / off time of the balancing switch controlled by a passive balancing algorithm. When the vehicle is powered off, the main controller (MBMU) and slave controller (SBMU) enter sleep mode. The slave controller (SBMU) accumulates sleep time, waking up the main controller (MBMU) when the sleep time exceeds 2 hours. The MBMU then calculates the balancing switch closing time and sends it to the slave controller (SBMU). The slave controller (SBMU) controls the balancing switch to open and close based on the closing time specified by the MBMU. This application comprehensively considers the consistency between cells within a single pack and the consistency between battery packs, performing passive balancing continuously 24 hours a day. This significantly shortens the balancing time and maintains optimal consistency across the multi-pack system, maximizing the charging and discharging capacity of the multi-pack parallel system.

[0023] like Figure 1 As shown, this application provides a battery multi-pack parallel system, including a main controller MBMU and N battery packs Pack(1), ..., Pack(n), ..., Pack(N) connected in parallel to the high-voltage bus, where N is the total number of battery packs and Pack(n) represents the nth battery pack, n=1...N; A single battery consists of M cells connected in series: Cell(1), ..., Cell(m), ..., Cell(M); M corresponding equalization switches: S(1), ..., S(m), ..., S(M); and M+1 equalization resistors: RBAL(0), RBAL(1), ..., RBAL(m), ..., RBAL(M). The two ends of the M cells connected in series are connected to points A and B of the battery pack, respectively. The m-th cell Cell(m) is connected to the two ends of the corresponding equalization switch S(m) via RBAL(0), RBAL(1), ..., RBAL(m), ..., RBAL(M). AL(m-1) and RBAL(m) are connected, m=1…M; point A of the battery pack is connected to the positive terminal HV_Bus+ of the high-voltage bus, and point B is connected to the negative terminal HV_Bus- of the high-voltage bus. A relay switch K(n) is set between point A and the positive terminal of the high-voltage bus or between point B and the negative terminal of the high-voltage bus. K(n) represents the relay switch of the nth battery pack. Each battery pack is equipped with a slave controller SBMU(n). SBMU(n) represents the slave controller in the nth battery pack. Each battery pack has a signal connection between the slave controller and the master controller (MBMU).

[0024] Figure 1 In the diagram, RBAL(m-1) and RBAL(m) represent equalization resistors, responsible for releasing the excess capacity of the corresponding m-th cell; S(m) represents the equalization switch corresponding to the m-th cell Cell(m); points A and B are the total voltage sampling points in the battery pack; UPack(n) represents the voltage of the nth battery pack; UCell(m) represents the voltage of the m-th cell in the battery pack; and IPack(n) represents the current sampling value of the nth battery pack.

[0025] like Figure 2 As shown in the embodiments of this application, a method for equalization control of the above-mentioned multi-pack parallel battery system is also provided, including: Before the vehicle goes into hibernation, the main controller MBMU controls all the relay switches in all N battery packs to disconnect and enter hibernation in all N battery packs. It starts to count the hibernation time. When the hibernation time reaches the first time T1 (2h), all N battery packs' slave controllers wake up and wake up the main controller MBMU. Step 3: After the nth battery pack wakes up from the controller SBMU(n), it sends the voltage UPack(n), the voltage of all cells UCell(m), and the remaining capacity CellSOC(m) of the cells to the main controller MBMU via CAN message. The main controller MBMU then performs inter-packet equalization judgment. Based on all N battery pack voltages UPack(n), determine the maximum battery pack voltage UPack_Max and the minimum battery pack voltage UPack_Min; If UPack_Max - UPack_Min > UPack_Max * 5%, calculate the equalization time within each battery pack and send it to the corresponding SBMU (Slave Controller Unit) via CAN bus. If UPack_Max - UPack_Min ≤ UPack_Max * 5%, disable inter-packet equalization, set the inter-packet equalization time to 0, disconnect all equalization switches in all battery packs, and control the SBMU in all battery packs to enter sleep mode. Set the wake-up time of the real-time clock RTC to the first time T1 (2h). After the real-time clock RTC wakes up, the inter-packet equalization judgment is performed again.

[0026] In some embodiments, such as Figure 3 As shown, the equalization time within each battery pack is calculated separately, including: Calculate the difference UPack_D(n) between the voltage UPack(n) of the nth battery pack and the minimum battery pack voltage UPack_Min. Determine the minimum cell voltage UCell_Min(n) in the nth battery pack based on the voltages of the M cells UCell(m) in the nth battery pack. Determine the minimum remaining cell capacity CellSOC_Min(n) in the nth battery pack based on the remaining capacity of the M cells CellSOC(m) in the nth battery pack. (1) If UPack(n)-UPack_Min≤UPack_Max*1%, turn off the inter-packet equalization, set the inter-packet equalization time to 0, disconnect all equalization switches in the nth battery pack, and control the controller SBMU(n) in the nth battery pack to enter sleep mode, and set the real-time clock RTC wake-up time to the first time T1 (2h). After the real-time clock RTC wakes up, the inter-packet equalization judgment is performed again. (2) If UPack(n)-UPack_Min>UPack_Max*1%, and CellSOC_Min(n)≤95%, enable inter-packet equalization, enable all equalization switches in the nth battery pack, and control the controller SBMU(n) in the nth battery pack to enter sleep mode and set the real-time clock RTC wake-up time to the second time T2 (1h). After the real-time clock RTC wakes up, the inter-packet equalization judgment is performed again. (3) If UPack(n)-UPack_Min>UPack_Max*1%, and CellSOC_Min(n)>95%, calculate the difference between the voltage of the m-th cell UCell(m) and the minimum cell voltage UCell_Min(n) in the battery pack, UCell_D(m), and the difference between the remaining capacity of the m-th cell CellSOC(m) and the remaining capacity of the minimum cell in the battery pack CellSOC_Min(n), CellSOC_D(m); UCell_D(m)=UCell(m)-UCell_Min(n); CellSOC_D(m)=CellSOC(m)-CellSOC_Min(n); Sort the M CellSOC_D(m) in descending order and store them in the first sequence CellSOC_D_Aarry[], and store the M UCell_D(m) in the second sequence UCell_D_Aarry[] according to the cell order in the first sequence; Based on the voltage UPack(n) of the nth battery pack and the second sequence UCell_D_Aarry[], determine the equalization switches that need to be turned on in the nth battery pack and the number of switches K. Specifically, this includes: counting the number of equalization switches K that need to be turned on in the battery pack and setting the initial value of K to 1; calculating the equalization voltage UPack_Ball[K] based on the number of switches K and the second sequence UCell_D_Aarry[], UPack_Ball[K]=∑UCell_D_Aarry[k], k=1,…,K; K=K+1, until UPack_Ball[K]≥UPack_D(n) and UPack_Ball(K-1)<UPack_D(n), and determining the equalization switches corresponding to the first K cells in the second sequence as the equalization switches that need to be turned on in the battery pack. Based on the battery capacity and remaining capacity of the corresponding cell, calculate the equalization time of the K equalization switches that need to be turned on: CellBall_T[k] = CAP * CellSOC_D_Aarry[k], k = 1, ..., K, where CAP represents the battery capacity of the cell corresponding to the equalization switch; If CellBall_T[k] > 0, turn on the corresponding equalization switch, and control the controller SBMU(n) in the nth battery pack to enter sleep mode and set the real-time clock RTC wake-up time to the second time T2 (1h). After the real-time clock RTC wakes up, the inter-packet equalization judgment is performed again. If CellBall_T[k]=0, turn off the corresponding equalization switch, and control the controller SBMU(n) in the nth battery pack to enter sleep mode and set the real-time clock RTC wake-up time to the first time T1 (2h). After the real-time clock RTC wakes up, the inter-packet equalization judgment is performed again.

[0027] It should be noted that the equalization time within the battery pack is calculated and sent to the corresponding slave controller within the battery pack via the CAN bus; after the equalization judgment is completed, the master controller MBMU enters sleep mode, and the slave controller controls the equalization switch within the corresponding battery pack to close, with the closing time being the equalization time requested by the master controller MBMU.

[0028] This application embodiment also provides a new energy vehicle, which is equipped with the above-mentioned multi-pack parallel battery system and uses the above-mentioned equalization control method for passive equalization.

[0029] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0030] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0031] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0032] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0033] The above description is only a preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A battery multi-pack parallel system, characterized by, The main controller and N battery packs connected in parallel to the high-voltage bus; Each battery pack comprises M battery cells connected in series, M balancing switches and M+1 balancing resistors, the two ends of the M battery cells are connected to the total voltage sampling points A and B of the battery pack, each battery cell and the corresponding balancing switch are connected by a balancing resistor to form a balancing loop, the total voltage sampling point A is connected to the positive pole of the high-voltage bus, and the total voltage sampling point B is connected to the negative pole of the high-voltage bus; and a relay switch is arranged between the total voltage sampling point A and the positive pole of the high-voltage bus or between the total voltage sampling point B and the negative pole of the high-voltage bus. Each battery pack is provided with a slave controller, and all the slave controllers are connected to the main controller.

2. The equalization control method of the battery multi-pack parallel system according to claim 1, characterized by, Before the whole vehicle sleeps, the main controller controls all the slave controllers in the N battery packs to disconnect all the relay switches, and controls all the slave controllers in the N battery packs to enter sleep, and starts to count the sleep time, when the sleep time reaches the first time T1, all the slave controllers in the N battery packs are self-awakened and the main controller is awakened; The slave controllers in the N battery packs respectively send the voltage UPack(n) of the corresponding battery pack, the voltage UCell(m) of each battery cell in the battery pack and the remaining capacity CellSOC(m) of each battery cell to the main controller; wherein UPack(n) represents the voltage of the nth battery pack, n=1…N; UCell(m) and CellSOC(m) represent the voltage and the remaining capacity of the mth battery cell in the battery pack, m=1…M; The main controller MBMU performs inter-pack balancing judgment, including: According to all the N battery pack voltages UPack(n), the maximum battery pack voltage UPack_Max and the minimum battery pack voltage UPack_Min are determined; If UPack_Max-UPack_Min>UPack_Max*a, for each battery pack, the intra-pack balancing time is calculated and sent to the corresponding slave controller in the battery pack through the CAN bus; a is a number between 0 and 1; If UPack_Max-UPack_Min≤UPack_Max*a, the inter-pack balancing is closed, the inter-pack balancing time is set to 0, all the balancing switches in all the battery packs are disconnected, and all the slave controllers in all the battery packs are controlled to enter sleep, and the real-time clock wake-up time is set to the first time T1, after the real-time clock RTC is woken up, the inter-pack balancing judgment is performed again. For each battery pack, the intra-pack balancing time is calculated, including:

3. The equalization control method of the battery multi-pack parallel system according to claim 2, characterized by, The difference UPack_D(n) between the nth battery pack voltage UPack(n) and the minimum battery pack voltage UPack_Min is calculated, the minimum battery cell voltage UCell_Min(n) in the nth battery pack is determined according to the M battery cell voltages UCell(m) in the nth battery pack, and the minimum battery cell remaining capacity CellSOC_Min(n) in the nth battery pack is determined according to the M battery cell remaining capacities CellSOC(m) in the nth battery pack. ​ If UPack(n)-UPack_Min>UPack_Max*b, and CellSOC_Min(n)>c, calculate the difference between the mth section cell voltage and the minimum cell voltage in the battery pack UCell_D(m) and the difference between the mth section cell remaining capacity and the minimum cell remaining capacity in the battery pack CellSOC_D(m); sort the M CellSOC_D(m) from large to small and store them in the first sequence CellSOC_D_Aarry[], and store the M UCell_D(m) in the second sequence UCell_D_Aarry[] according to the corresponding cell order in the first sequence; According to the nth battery pack voltage and the second sequence, determine the equalization switch that needs to be turned on in the nth battery pack and the switch number K; According to the battery capacity and the remaining capacity of the corresponding cell, calculate the equalization time CellBall_T[k] of the K equalization switches that need to be turned on; If CellBall_T[k]>0, turn on the corresponding equalization switch, control the nth battery pack to enter sleep from the controller and set the real-time clock wake-up time to the second time T2, and re-perform inter-pack equalization judgment after the real-time clock wakes up; If CellBall_T[k]=0, turn off the corresponding equalization switch, control the nth battery pack to enter sleep from the controller and set the real-time clock wake-up time to the first time T1, and re-perform inter-pack equalization judgment after the real-time clock wakes up.

4. The equalization control method of the battery multi-pack parallel system according to claim 3, characterized by, According to the nth battery pack voltage and the second sequence, determine the equalization switch that needs to be turned on in the nth battery pack and the switch number K, including: S1, count the switch number K of the equalization switch that needs to be turned on in the battery pack, and set K initial value as 1; S2, according to the switch number K and the second sequence UCell_D_Aarry[], calculate the equalization voltage UPack_Ball[K], UPack_Ball[K]=∑UCell_D_Aarry[k], k=1,…,K; S3, if UPack_Ball[K]≥UPack_D(n) and UPack_Ball(K-1)<UPack_D(n) are not met, K=K+1; S4, repeat steps S2-S4 until UPack_Ball[K]≥UPack_D(n) and UPack_Ball(K-1)<UPack_D(n) are met, and determine that the first K cells in the second sequence correspond to the equalization switch that needs to be turned on in the battery pack.

5. The balancing control method of the battery multi-pack parallel system according to claim 3, characterized by, Further comprising: If UPack(n)-UPack_Min≤UPack_Max*b, turn off the inter-pack equalization, set the inter-pack equalization time to 0, disconnect all equalization switches in the nth battery pack, control the nth battery pack to enter sleep from the controller, and set the real-time clock wake-up time to the first time T1, and re-perform inter-pack equalization judgment after the real-time clock wakes up.

6. The balancing control method of the battery multi-pack parallel system according to claim 3, characterized by, Further comprising: If UPack(n)-UPack_Min>UPack_Max*b, and CellSOC_Min(n)≤c, start inter-pack balancing, open all balancing switches in the nth battery pack, and control the SBMU(n) in the nth battery pack to enter sleep and set the real-time clock wake-up time as the second time T2, and after the real-time clock wakes up, re-perform the inter-pack balancing judgment.

7. The equalization control method of the battery multi-pack parallel system according to claim 2, characterized by, a is 5%.

8. The equalization control method of the battery multiple pack parallel system according to claim 3, 5 or 6, characterized by, b is 1%.

9. The equalization control method of the battery multiple pack parallel system according to claim 3 or 6, characterized by, c is 95%.

10. The method of claim 3-6, wherein, The first time T1 is 2h; and / or, the second time T2 is 1h.

11. A new energy vehicle, characterized in that, The new energy vehicle is provided with the battery multi-pack parallel system as claimed in claim 1, and adopts the passive balancing method as claimed in any one of claims 2-10.

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