Battery module balancing method, battery module, electric vehicle and variable capacitor

Abstract

The present invention discloses a battery module balancing method, a battery module, an electric vehicle, and a variable capacitor. The electric vehicle includes a battery module, which includes multiple battery packs and a variable capacitor. The battery module balancing method includes first selecting any two battery packs from the multiple battery packs, obtaining the power parameters of the two battery packs, and calculating the power difference between the two battery packs; when the power difference reaches a preset balanced power difference, adjusting the power value that the variable capacitor can store based on the power difference, and controlling the variable capacitor to be connected in parallel with the battery pack with a higher power to charge the variable capacitor; when it is determined that the variable capacitor is in a fully charged state, controlling the variable capacitor to disconnect the path between the battery pack with a higher power and connect it in parallel with the battery pack with a lower power to charge the battery pack with a lower power, so that the power difference between the two battery packs is within the preset balanced power difference range. The present invention improves the efficiency of battery balancing.

Description

Technical Field

[0001] The present invention relates to the technical field of battery balancing, and in particular to a battery module balancing method, a battery module, an electric vehicle, and a variable capacitor. Background Art

[0002] To accommodate various power usage scenarios, existing battery modules often utilize a hybrid configuration of two battery packs, A+B, where A and B represent battery packs with different electrochemical systems. These two packs are typically connected in series. During use, this can lead to differential discharge and a resulting difference in charge between the two packs, necessitating battery balancing.

[0003] Traditional battery balancing technologies are categorized as passive and active. Passive balancing, also known as energy-consuming balancing, dissipates excess power as heat through a load connected in parallel with the battery, resulting in energy waste. Furthermore, because batteries are temperature-sensitive, passive balancing requires a relatively low discharge current, which reduces the efficiency of the entire balancing system. When the battery system is dynamically charged and discharged, the capacity differences between cells in different systems and states rapidly increase, making passive balancing difficult to adjust.

[0004] Active balancing can be categorized into various types, including capacitive balancing, inductive balancing, and transformer balancing, depending on the device used. Capacitors can quickly charge and discharge, facilitating rapid balancing between cells and meeting the dynamic balancing requirements of the battery system. During active balancing, capacitors can be switched in parallel between high- and low-capacity batteries or battery packs through various methods, such as power switches and flyback switches, to achieve energy transfer.

[0005] However, existing capacitor-based active balancing methods often use fixed capacitors, and the battery power transferred each time is fixed. As a result, during active balancing, if half of the power difference between battery packs A and B is greater than the maximum power value that the fixed capacitor can store, the balancing switch needs to be opened and closed multiple times to achieve power balancing between the two battery packs, which reduces system reliability and balancing efficiency. Summary of the Invention

[0006] The main purpose of the present invention is to provide a battery module balancing method, a battery module, an electric vehicle and a variable capacitor, aiming to improve the efficiency of battery balancing.

[0007] To achieve the above objectives, the present invention provides a battery module balancing method, which is applied to an electric vehicle. The electric vehicle includes a battery module, and the battery module includes multiple battery packs and a variable capacitor. The battery module balancing method includes:

[0008] Selecting any two battery packs from the plurality of battery packs, obtaining power parameters of the two battery packs, and calculating a power difference between the two battery packs;

[0009] When the charge difference reaches a preset balanced charge difference, adjusting the charge value that can be stored in the variable capacitor according to the charge difference, and controlling the variable capacitor to be connected in parallel with the battery pack with a higher charge, so as to charge the variable capacitor;

[0010] When it is determined that the variable capacitor is in a fully charged state, the variable capacitor is controlled to disconnect the path between it and the battery pack with higher charge, and is connected in parallel with the battery pack with lower charge to charge the battery pack with lower charge, so that the charge difference between the two battery packs is within a preset balanced charge difference range.

[0011] Optionally, the battery module further includes a motor assembly, and the step of adjusting the capacity value of the variable capacitor according to the power difference is specifically as follows:

[0012] detecting a voltage value of the battery pack with a higher charge, and calculating a required capacitance value of the variable capacitor according to the voltage value of the battery pack with a higher charge and the charge difference;

[0013] The motor assembly is controlled to drive the variable capacitor to operate, so that the capacitance value of the variable capacitor is adjusted to the required capacitance value.

[0014] Optionally, the step of determining whether the variable capacitor is in a fully charged state is specifically:

[0015] detecting a voltage value of the variable capacitor;

[0016] When it is determined that the voltage value of the variable capacitor remains constant within a preset time period, it is determined that the variable capacitor is in a fully charged state.

[0017] Optionally, the battery module balancing method further includes:

[0018] Obtaining the current reversible capacity of any of the battery packs, and calculating the attenuation capacity of the battery pack by subtracting the reversible capacity from the design capacity of the corresponding battery pack;

[0019] When the attenuation capacity of any of the battery packs reaches a preset charging capacity, the battery pack is determined to be in a decaying state, and the amount of electricity that can be stored by the variable capacitor is adjusted according to the attenuation capacity, and the variable capacitor is controlled to be connected in parallel with the battery pack in the decaying state to compensate for the reversible capacity of the battery pack.

[0020] Optionally, the battery module further has an output terminal and a charging terminal, and the battery module balancing method further includes:

[0021] When the power difference does not reach the preset balanced power difference, conducting a path between the variable capacitor and the charging end to charge the variable capacitor;

[0022] When an acceleration instruction is obtained, the path between the variable capacitor and the charging end is disconnected, and the path between the variable capacitor and the output end is connected, so that the variable capacitor is discharged through the output end.

[0023] The present invention further provides a variable capacitor, comprising:

[0024] A plurality of electrode sleeves, wherein the openings of the plurality of electrode sleeves are in the same direction, and the plurality of electrode sleeves are sequentially sleeved and arranged, and a capacitor is formed between any two of the electrode sleeves;

[0025] Each electrode sleeve and its adjacent electrode sleeve can be relatively far away from or close to each other along the axial direction, so as to change the capacitance value of the capacitor formed between the two.

[0026] Optionally, one of the adjacent electrode sleeves is a positive electrode sleeve and the other is a negative electrode sleeve, the positive electrode sleeves are connected in parallel to each other, and the negative electrode sleeves are connected in parallel to each other.

[0027] Optionally, the peripheral walls of the plurality of electrode sleeves are electrode sheets, and the bottom walls of the plurality of electrode sleeves are insulating sheets.

[0028] Optionally, the peripheral walls of the plurality of electrode sleeves are insulating sheets, and the bottom walls of the plurality of electrode sleeves are electrode sheets.

[0029] Optionally, the peripheral walls of the plurality of electrode sleeves are electrode sheets, and the bottom walls of the plurality of electrode sleeves are electrode sheets.

[0030] The present invention also provides a battery module for use in electric vehicles, the battery module comprising:

[0031] A plurality of battery packs, wherein the plurality of battery packs are sequentially connected in series;

[0032] Motor components;

[0033] an output end, the output end being used to output voltage to the electric vehicle;

[0034] A charging terminal, the charging terminal being used to access a charging voltage;

[0035] Equalizing switch assembly;

[0036] Memory;

[0037] a processor having a communication terminal for communicating with the electric vehicle;

[0038] a battery module balancing program stored in the memory and executed by the processor, wherein the battery module balancing program, when executed by the processor, implements any one of the above battery module balancing methods; and

[0039] A variable capacitor or a variable capacitor as described in any of the above;

[0040] The processor is respectively connected to the variable capacitor, the memory, the motor assembly, the two battery packs and the controlled end of the balancing switch assembly; the motor assembly is driven and connected to the variable capacitor; and the balancing switch assembly is respectively electrically connected to the variable capacitor, the two battery packs, the output end and the charging end.

[0041] Optionally, the type of at least one of the multiple battery packs is different from the types of the other battery packs.

[0042] Optionally, it includes a battery module as described in any of the above items.

[0043] In the solution of the present invention, any two battery packs are first selected from a plurality of battery packs, and the charge parameters of the two battery packs are obtained, and the charge difference between the two battery packs is calculated. Then, when the charge difference reaches a preset balanced charge difference, the amount of charge that the variable capacitor can store is adjusted according to the charge difference, and the variable capacitor is controlled to be connected in parallel with the battery pack with higher charge to charge the variable capacitor. When it is determined that the variable capacitor is in a fully charged state, the variable capacitor is controlled to disconnect the path between the battery pack with higher charge and be connected in parallel with the battery pack with lower charge to charge the battery pack with lower charge, so that the charge difference between the two battery packs is within the preset balanced charge difference range. In this way, in actual applications, the capacitance value of the variable capacitor can be adjusted accordingly according to the charge difference between the two battery packs to be balanced, thereby adjusting the amount of charge that the variable capacitor can store, thereby achieving a one-time completion of charge transfer without the need to repeatedly control the switch action, effectively improving the efficiency and reliability of battery balancing. At the same time, since the amount of electricity that the variable capacitor can store is adjusted according to the electricity difference, during the process of the high-capacity battery pack charging the variable capacitor, there is no need to disconnect the parallel relationship between the variable capacitor and the high-capacity battery pack in time according to the discharge status of the high-capacity battery pack. The problem of inaccurate sampling and reduced balancing accuracy caused by excessive charging and discharging of the variable capacitor will not occur, which greatly improves the accuracy of battery balancing. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0045] Figure 1 A schematic diagram of a method flow of an embodiment of a battery module balancing method according to the present invention;

[0046] Figure 2 A schematic diagram of a method flow chart of another embodiment of a battery module balancing method according to the present invention;

[0047] Figure 3 This is a schematic diagram of a method flow of another embodiment of a battery module balancing method of the present invention;

[0048] Figure 4 This is a flowchart of another embodiment of a battery module balancing method according to the present invention;

[0049] Figure 5 A schematic structural diagram of an embodiment of a variable capacitor according to the present invention;

[0050] Figure 6 is a structural schematic diagram of another embodiment of the variable capacitor of the present invention;

[0051] Figure 7 Schematic diagram of the structure of another embodiment of the variable capacitor of the present invention;

[0052] Figure 8 Schematic diagram of the structure of another embodiment of the variable capacitor of the present invention;

[0053] Figure 9 FIG. 1 is a schematic diagram of a battery module according to an embodiment of the present invention.

[0054] Description of Figure Numbers:

[0055] Label name Label name 11 Battery Pack A 12 Battery Pack B 20 Motor components 31 SPDT switch A 32 SPDT switch B 33 Switch A 34 Switch B 40 Memory 50 processor 60 variable capacitors 100 Electrode sleeve 110 The peripheral wall of the electrode sleeve 120 Bottom wall of the electrode sleeve 130 Upper card 140 Lower card 150 Fixed column 160 Support sheet

[0056] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0057] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0058] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0059] To accommodate various power usage scenarios, existing battery modules often utilize a hybrid configuration of two battery packs, A+B, where A and B represent battery packs with different electrochemical systems. These two packs are typically connected in series. During use, this can lead to differential discharge and a resulting difference in charge between the two packs, necessitating battery balancing.

[0060] Traditional battery balancing technologies are categorized as passive and active. Passive balancing, also known as energy-dissipating balancing, involves dissipating excess power as heat through a load connected in parallel with the battery, resulting in energy waste. Furthermore, because batteries are temperature-sensitive, passive balancing requires a relatively low discharge current, which reduces the efficiency of the entire balancing system. When the battery system is dynamically charging and discharging, the capacity differences between cells in different systems and states rapidly increase, making passive balancing difficult to adjust. Active balancing, on the other hand, can be categorized into various types, including capacitive balancing, inductive balancing, and transformer balancing, depending on the device used. Capacitors can charge and discharge quickly, facilitating rapid balancing between cells and meeting the dynamic balancing requirements of the battery system. During active balancing, capacitors can be switched in parallel between cells or battery packs with high and low charge levels, using various methods, such as power switches and fly-by switches, to transfer energy. However, existing capacitor-based active balancing methods often use fixed capacitors, and the battery power transferred each time is fixed. As a result, during active balancing, if half of the power difference between battery packs A and B is greater than the capacitance value of the fixed capacitor, the balancing switch needs to be opened and closed multiple times to achieve power balancing between the two battery packs, which reduces system reliability and balancing efficiency.

[0061] To this end, the present invention proposes a battery module balancing method, a battery module, an electric vehicle, and a variable capacitor. The battery module balancing method is applied to an electric vehicle, which includes a battery module, which includes multiple battery packs and a variable capacitor.

[0062] The multiple battery packs are connected in series and have the same capacity, that is, when the battery packs are fully charged, their capacities should be the same. The variable capacitor can be an air dielectric variable capacitor or a solid dielectric variable capacitor.

[0063] refer to Figure 1 In one embodiment of the present invention, a battery module balancing method includes:

[0064] Step S100: Select any two battery packs from a plurality of battery packs, obtain power parameters of the two battery packs, and calculate the power difference between the two battery packs;

[0065] In this embodiment, a processor can be installed within the battery module, and the battery pack often integrates a BMS and battery cells. The BMS detects the battery parameters of the current battery cells, such as current charge, total capacity, and reversible capacity, and reports these parameters to the processor. During the balancing process, the processor selects any two battery packs from the multiple batteries and determines the current charge difference between the two packs based on the data uploaded by its internal BMS.

[0066] Step S200: When the charge difference reaches a preset equilibrium charge difference, the amount of charge that can be stored in the variable capacitor is adjusted according to the charge difference, and the variable capacitor is connected in parallel with the battery pack with a higher charge to charge the variable capacitor;

[0067] In this embodiment, the preset balanced charge difference can be obtained by R&D personnel based on multiple tests during the R&D period and pre-stored in the processor within the battery module. When the processor within the battery module determines that the charge difference between two selected battery packs reaches the preset balanced charge difference, it will perform a battery balancing step. In addition, if the charge difference between the two selected battery packs within the battery module does not reach the preset balanced charge difference, the processor will select two other battery packs and repeat the charge difference determination step. For example, if the current battery module includes battery pack A, battery pack B, and battery pack C, and the processor determines that the charge difference between battery pack A and battery pack B does not reach the preset balanced charge difference, it will select battery packs B and battery pack C, or battery pack A and battery pack C, and determine the charge difference between the two battery packs to determine whether the two selected battery packs need to be balanced. This ensures that the charge difference between any two battery packs among the multiple battery packs within the battery module is lower than the preset balanced charge difference, thereby ensuring that the multiple battery packs within the battery module maintain good charge consistency.

[0068] In this embodiment, the battery module may further include a balancing switch component. Under the control of the processor, the balancing switch component may connect the variable capacitor in parallel with any battery pack individually, even if the variable capacitor and any battery pack can be connected in parallel.

[0069] When the processor determines that the charge difference between the two selected battery packs reaches the preset balanced charge difference, the charge value that the variable capacitor can store is adjusted according to the charge difference. Optionally, the charge value that the variable capacitor can store can be set to exactly half of the charge difference. In this way, after the charge transfer between the high-charge battery pack and the low-charge battery pack is completed, the charge values ​​of the two battery packs can be exactly balanced. It is understandable that, considering the residual and error in the charging and discharging of the capacitor, the charge value that the variable capacitor can store can be adjusted to 55%, 60% or 70% of the charge difference, so that the charge difference between the two battery packs after the charge transfer is within the preset balanced charge difference.

[0070] Specifically, the steps of adjusting the capacitance value of the variable capacitor according to the power difference are as follows:

[0071] Detecting the voltage value of the battery pack with a higher charge, and calculating the required capacitance value of the variable capacitor based on the voltage value of the battery pack with a higher charge and the charge difference;

[0072] The motor assembly is controlled to drive the variable capacitor to operate so that the capacitance value of the variable capacitor is adjusted to a required capacitance value.

[0073] In this embodiment, based on the relationship between the battery pack's capacity unit, AH, and the charge unit, C: 1AH = 3600C, and the capacity difference, the content processor can calculate the current charge value that the variable capacitor needs to store, referring to the above-mentioned embodiment. For example, if the current capacity difference is 5AH and the required amount of energy to be transferred is half of the capacity difference, the variable capacitor can be calculated to have a charge value of 9000C.

[0074] The processor then calculates the required capacitance of the variable capacitor based on the formula for the amount of charge stored in the variable capacitor: Q = C * U (Q is the amount of charge that the variable capacitor can store, C is the capacitance of the variable capacitor, and U is the voltage across the variable capacitor), as well as the current voltage of the high-capacity battery obtained by the BMS. When selecting a variable capacitor, its rated voltage should be higher than the maximum voltage of the battery pack.

[0075] It should be understood that the air dielectric variable capacitor in the variable capacitor is generally provided with a special knob. By twisting the knob, the relative area between the moving plate and the fixed plate can be changed. Optionally, a motor assembly for twisting the variable capacitor knob under the control of the processor can also be provided in the battery module. The processor controls the motor assembly to twist the knob to a certain angle according to the power difference based on the preset rotation angle-capacitance value mapping table, so that the capacitance value of the variable capacitor is the required capacitance value mentioned above. Among them, the preset rotation angle-capacitance value mapping table is obtained by the R&D personnel through multiple tests and is pre-stored in the processor. After adjusting the capacitance value of the variable capacitor, the processor controls the action of the balancing switch assembly to connect the variable capacitor in parallel with the high-power batteries in the two battery packs, so that the high-power batteries charge the variable capacitor.

[0076] Optionally, in another embodiment, the variable capacitor may also be the variable capacitor proposed in the present invention, which is a pull-rod type variable capacitor. Figure 5 , the processor can control the motor assembly to pull the middle electrode sleeve of the variable capacitor to move, and after the middle electrode sleeve is completely pulled out, the middle electrode sleeve drives the outer circle of electrode sleeves to move, thereby changing the capacitance value of the capacitor formed between the multiple electrode sleeves, and then changing the capacitance value of the variable capacitor. The processor can control the motor assembly to pull the middle electrode sleeve of the variable capacitor out a certain distance according to the power difference according to the preset extension distance-capacitance value mapping table, so that the capacitance value of the variable capacitor is the required capacitance value mentioned above. After adjusting the capacitance value of the variable capacitor, the processor controls the action of the balancing switch assembly to connect the variable capacitor in parallel with the high-power battery in the two battery packs, so that the high-power battery charges the variable capacitor.

[0077] Step S300: When it is determined that the variable capacitor is in a fully charged state, the variable capacitor is controlled to disconnect the path between the battery pack with higher power and be connected in parallel with the battery pack with lower power to charge the battery pack with lower power, so that the power difference between the two battery packs is within a preset balanced power difference range.

[0078] Optionally, in this embodiment, since the variable capacitor has the characteristics of fast charging and discharging, the power of the high-power battery pack decreases rapidly during the charging of the variable capacitor. The processor can determine that the variable capacitor is currently in a fully charged state when it determines that the power of the high-power battery has dropped by half of the power difference based on the battery parameter information feedback from the BMS of the high-power battery pack.

[0079] Optionally, in another embodiment, reference Figure 2 , the steps to determine when the variable capacitor is in a fully charged state are:

[0080] Step S310, detecting the voltage value of the variable capacitor;

[0081] Step S320: When it is determined that the voltage value of the variable capacitor remains constant within the preset time period, it is determined that the variable capacitor is in a fully charged state.

[0082] In this embodiment, an ADC detection module may be integrated within the processor to detect the voltage value of the variable capacitor. When the variable capacitor is fully charged, the voltage value of the variable capacitor does not change. When the voltage value of the variable capacitor remains constant for a preset period of time, it can be considered that the variable capacitor is currently fully charged.

[0083] In another embodiment, a voltage detection component may be provided within the battery module. The voltage detection component may be implemented using a voltage-dividing sampling circuit, a voltage detection chip, or the like, to detect the voltage value of the variable capacitor and output a corresponding voltage detection signal to the processor, so that the processor can determine the current voltage value of the variable capacitor. When the processor confirms that the current voltage value of the variable capacitor remains constant for a preset period of time, the variable capacitor may be considered to be fully charged.

[0084] Similarly, in another embodiment, a current detection module may be provided in the battery module to detect the charging current flowing into the variable capacitor. When the charging current flowing into the variable capacitor remains close to 0 within a preset period of time, it can be considered that the variable capacitor is currently in a fully charged state.

[0085] In this embodiment, when the variable capacitor is fully charged, the processor controls the variable capacitor to disconnect from the parallel path with the high-charge battery pack and connect the variable capacitor in parallel with the low-charge battery pack, allowing the variable capacitor to discharge the low-charge battery pack. In this way, in practical applications, the capacitance of the variable capacitor can be adjusted continuously based on the charge difference between the two battery packs to be balanced and the voltage of the high-charge battery, thereby continuously adjusting the amount of charge that the variable capacitor can store. This allows for a one-time charge transfer, eliminating the need for repeated switching operations and effectively improving the efficiency and reliability of battery balancing.

[0086] Specifically, refer to Figure 9 , take the battery module including battery pack A and battery pack B as an example for explanation, where the current power of battery pack A is 40AH, the current power of battery pack B is 60AH, and the preset balancing power difference is 10AH.

[0087] At this point, the processor determines that the charge difference between battery pack A and battery pack B is 20AH, which is greater than the preset equalization charge difference. It then controls the motor assembly to drive the variable capacitor in accordance with the above-described embodiment, so that the variable capacitor can store 10AH of charge (using a 50% charge transfer as an example). It also controls single-pole double-throw switches A and B to connect the positive and negative poles of the variable capacitor in parallel with the positive and negative poles of battery pack A, respectively, thereby connecting the variable capacitor and battery pack A in parallel and allowing battery pack A to charge the variable capacitor. When the processor determines that the voltage of the variable capacitor remains constant for a preset time period, it determines that the variable capacitor is currently fully charged. It then controls single-pole double-throw switches A and B to disconnect the variable capacitor from the parallel connection with battery pack A and connect the variable capacitor to battery pack B in parallel, causing the variable capacitor to discharge battery pack B, so that the charge difference between battery packs A and B falls within the preset equalization charge difference range.

[0088] In the solution of the present invention, any two battery packs are first selected from a plurality of battery packs, and the charge parameters of the two battery packs are obtained, and the charge difference between the two battery packs is calculated. Then, when the charge difference reaches a preset balanced charge difference, the amount of charge that the variable capacitor can store is adjusted according to the charge difference, and the variable capacitor is controlled to be connected in parallel with the battery pack with higher charge to charge the variable capacitor. When it is determined that the variable capacitor is in a fully charged state, the variable capacitor is controlled to disconnect the path between the battery pack with higher charge and be connected in parallel with the battery pack with lower charge to charge the battery pack with lower charge, so that the charge difference between the two battery packs is within the preset balanced charge difference range. In this way, in actual applications, the capacitance value of the variable capacitor can be adjusted accordingly according to the charge difference between the two battery packs to be balanced, thereby adjusting the amount of charge that the variable capacitor can store, thereby achieving a one-time completion of charge transfer without the need to repeatedly control the switch action, effectively improving the efficiency and reliability of battery balancing. At the same time, since the amount of electricity that the variable capacitor can store is adjusted according to the electricity difference, during the process of the high-capacity battery pack charging the variable capacitor, there is no need to disconnect the parallel relationship between the variable capacitor and the high-capacity battery pack in time according to the discharge status of the high-capacity battery pack. The problem of inaccurate sampling and reduced balancing accuracy caused by excessive charging and discharging of the variable capacitor will not occur, which greatly improves the accuracy of battery balancing.

[0089] It should be understood that since at least one battery pack in a battery module is of a different type than the other battery packs, different types of battery packs may have different reversible capacities after the same charge and discharge cycle, which causes excessive attenuation of the reversible capacity of the entire battery module.

[0090] For this purpose, refer to Figure 3In one embodiment of the present invention, the battery module balancing method further includes:

[0091] Step S400: Obtain the current reversible capacity of any battery pack, and calculate the attenuation capacity of the battery pack by subtracting it from the design capacity of the corresponding battery pack;

[0092] Step S500: When the attenuation capacity of any battery pack reaches the preset charging capacity, determine that the battery pack is in a decay state, adjust the amount of electricity that the variable capacitor can store, and control the variable capacitor to be connected in parallel with the battery pack in the decay state to compensate for the reversible capacity of the battery pack.

[0093] It's important to understand that reversible capacity is the actual capacity of a battery pack's cells that can still be charged and discharged after multiple charge-discharge cycles. When the battery pack's cells are fresh from the factory, their reversible capacity is equal to their design capacity. However, after multiple charge-discharge cycles, the cells begin to degrade, and the reversible capacity will be less than the design capacity.

[0094] In this embodiment, the BMS in any battery pack will monitor the charge and discharge cycle status of the battery cell by itself, and after determining the reversible capacity of the current battery cell, upload its reversible capacity parameters to the processor. The processor will determine the attenuation capacity of the current battery pack based on the design capacity of the corresponding battery pack.

[0095] When the attenuation capacity is excessive and reaches the preset recharge capacity, the processor determines that the current battery pack is in a decay state and, in accordance with the scheme in the above embodiment, controls the motor assembly in the above embodiment to adjust the capacitance of the variable capacitor according to the attenuation capacity, thereby adjusting the amount of electricity that the variable capacitor can store. Optionally, the amount of electricity that the adjusted variable capacitor can store can directly be the attenuation capacity, so that the capacity of the compensated battery pack is restored to the designed capacity; or the amount of electricity that the variable capacitor can store can be adjusted based on the current reversible capacity of other battery packs at the same time, so that the capacity of the compensated battery pack is similar to the reversible capacity of the other battery packs.

[0096] After adjusting the variable capacitor, the processor controls the balancing switch assembly to connect the variable capacitor in parallel with the battery pack in the decaying state, thereby replenishing the decayed capacity of the battery pack in the decaying state, thereby improving the service life and output capacity of the entire battery module. It should be noted that in this embodiment, when calculating the required capacitance value of the variable capacitor, the voltage across the variable capacitor (i.e., the U value) should be the voltage that the battery in the decaying state should reach when fully charged after compensation (which can be determined by the SOC curve output by the BMS).

[0097] Specifically, refer to Figure 9This example uses a battery module containing a ternary NCM battery pack and a lithium iron phosphate (LFP) battery pack, and compensates the degraded battery pack to its designed capacity. Battery pack A is a ternary NCM battery pack, and battery pack B is a lithium iron phosphate (LFP) battery pack. The cells in the ternary NCM battery pack degrade faster than those in the LFP battery pack. Both the ternary NCM and LFP battery packs have a designed capacity of 100AH. After several charge and discharge cycles, the reversible capacity of the LFP battery pack is 95AH, while that of the ternary NCM battery pack is 70AH. The preset recharge capacity is 20AH.

[0098] The BMSs within battery packs A and B monitor the current reversible capacity of the battery packs and transmit this information to the processor in real time. Based on the reversible capacity transmitted from the BMS, the processor determines that the current reversible capacity of the LFP battery pack is 95AH, and the reversible capacity of the NCM battery pack is 70AH. The processor also calculates that the current attenuation capacity of the LFP battery pack is 5AH, and the current attenuation capacity of the NCM battery pack is 30AH. This determines that battery pack B, currently the LFP battery pack, is not in a decay state, and that battery pack A, currently the NCM battery pack, is in a decay state. The processor then controls the motor assembly according to the above-described embodiments, thereby adjusting the capacitance of the variable capacitor and, consequently, the amount of charge that the variable capacitor can store, so that its stored charge equals the attenuation capacity of battery pack A, 30AH. The processor also controls the balancing switch assembly to connect the variable capacitor in parallel with battery pack B to supplement the attenuation capacity of battery pack B.

[0099] Through the above settings, it is possible to adjust the capacitance value of the variable capacitor steplessly and thus adjust the amount of electricity that the variable capacitor can store, so as to replenish the capacity of the battery pack in the attenuated state in the battery module, thereby improving the service life and output capacity of the entire battery module.

[0100] refer to Figure 4 In one embodiment of the present invention, the battery module balancing method further includes:

[0101] Step S500: When the power difference does not reach the preset balanced power difference, the path between the variable capacitor and the charging terminal is turned on to charge the variable capacitor;

[0102] Step S600: When an acceleration instruction is obtained, the path between the variable capacitor and the charging end is disconnected, and the path between the variable capacitor and the output end is connected, so that the variable capacitor is discharged through the output end.

[0103] In this embodiment, when the charge difference does not reach the preset balanced charge difference, that is, when the multiple battery packs in the current battery module can meet the consistency condition. Then the battery module can be controlled to control the switch action to conduct the path between the variable capacitor and the charging end. At this time, the capacitance value of the variable capacitor can be adjusted to any value, such as a preset maximum value, to increase the stored charge value. It is understandable that the charging end of the battery module can be used to access the charging voltage, such as the charging voltage output by the charging head of the external charging pile or the charging voltage output by the generator in the electric vehicle. In this way, when multiple battery packs meet the consistency, the idle variable capacitor can be charged, and when it is determined that the variable capacitor is in a fully charged state or the processor obtains an acceleration instruction, the switch can be controlled to act again to disconnect the path between the charging end and the variable capacitor. Among them, the rated voltage of the variable capacitor is greater than the charging voltage output by the charging end.

[0104] In this embodiment, when the battery module is installed in an electric vehicle, the processor is also provided with a communication terminal for communicating with the vehicle controller of the electric vehicle, thereby enabling the processor in the battery module and the vehicle controller in the electric vehicle to transmit data to each other.

[0105] It is understandable that another switch is also provided in the battery module, which is respectively connected to the output end and the variable capacitor. When the vehicle controller transmits an acceleration instruction, the processor will control the above-mentioned switch action to open the path between the variable capacitor and the output end, so that the variable capacitor can discharge the electric vehicle directly through the output end, that is, discharge the driving component of the electric vehicle, so as to improve the instantaneous peak output capacity of the battery module, so that the electric vehicle has better acceleration performance and improves the user comfort.

[0106] Specifically, refer to Figure 9 Battery pack A and battery pack B are connected in series, and battery pack A is electrically connected to the output end through an output switch (not shown in the figure), so that battery pack A and battery pack B are connected in series and discharge to the electric vehicle through the output end.

[0107] When the multiple battery packs meet consistency, the processor controls switch B to close to conduct the path between the charging terminal and the variable capacitor, thereby charging the variable capacitor.

[0108] When the vehicle is running normally, the processor controls the output switch to be in a closed state to open the path between the series-connected battery pack A and battery pack B and the output end, so that the battery pack A and battery pack B are connected in series to discharge the electric vehicle.

[0109] When the processor receives an acceleration instruction, it controls switch B to be in the open state and controls switch A to be in the closed state, so that the variable capacitor also discharges to the electric vehicle through the output end. At this time, if the voltage value of the variable capacitor is close to the voltage value of battery pack A and battery pack B, the output switch action can be uncontrolled, that is, the variable capacitor is discharged in parallel to the electric vehicle through the output end together with the battery pack A and battery pack B connected in series. When the voltage value of the variable capacitor is not close to the voltage value of battery pack A and battery pack B, the output switch needs to be disconnected to allow the variable capacitor to discharge quickly alone. In this way, through the above two discharge methods, the instantaneous peak output capacity of the battery module can be instantly improved, so that the electric vehicle has better acceleration performance and improves the comfort of user use.

[0110] refer to Figure 5 and Figure 6 The present invention further proposes a variable capacitor, comprising:

[0111] A plurality of electrode sleeves, wherein the openings of the plurality of electrode sleeves are in the same direction, and the plurality of electrode sleeves are sequentially sleeved and arranged, and a capacitor is formed between any two of the electrode sleeves;

[0112] Each electrode sleeve and its adjacent electrode sleeve can be relatively far away from or close to each other along the axial direction, so as to change the capacitance value of the capacitor formed between the two.

[0113] Among them, one of the adjacent electrode sleeves is a positive electrode sleeve and the other is a negative electrode sleeve, the positive electrode sleeves are connected in parallel with each other, and the negative electrode sleeves are connected in parallel with each other.

[0114] In this embodiment, each electrode sleeve includes a bottom wall and a peripheral wall. A plurality of electrode sleeves are sleeved on a fixing column 150 , which is made of insulating material.

[0115] Among them, when multiple electrode sleeves are sleeved on the fixed column 150, the diameter of the bottom wall of the electrode sleeve increases from the innermost side to the outermost side. The innermost electrode sleeve is only provided with multiple lower retaining pieces 130 on the peripheral wall parallel to the bottom wall, and the outermost electrode sleeve is only provided with multiple upper retaining pieces 140 inwardly near the beginning of the peripheral wall. The other intermediate electrode sleeves are also provided with multiple lower retaining pieces 130 and multiple upper retaining pieces 140 at the corresponding positions mentioned above, and the lower retaining pieces 130 are slightly longer than the upper retaining pieces 140. The multiple lower retaining pieces 130 on each electrode sleeve are aligned with the multiple upper retaining pieces 140 on the outer electrode sleeve, so that when a certain electrode sleeve is pulled out, the lower retaining pieces 130 on the electrode sleeve will overlap with the upper retaining pieces 140 on the outer layer, so that when the electrode sleeve is pulled out a certain distance, the outer electrode sleeve will be pulled out at the same time.

[0116] In this embodiment, multiple positive electrode sleeves can be connected in parallel by means of bonding or contact point wiring. Similarly, multiple negative electrode sleeves can be connected in parallel by means of bonding or contact point wiring. Figure 5 , a contact can be provided on the innermost negative electrode sleeve as a total negative contact, and a contact can also be provided on the outermost positive electrode sleeve as a total positive contact. These two contacts are the positive and negative terminals of the variable capacitor. Thus, in practical applications, according to the capacitor formula, only a motor assembly or other drag assembly is needed to drive the innermost electrode sleeve to move, thereby changing the facing area between the peripheral walls of multiple adjacent electrode sleeves, and also changing the distance between the bottom walls of multiple adjacent electrode sleeves, thereby actually changing the capacitance value of the variable capacitor of the present invention and realizing stepless adjustment of the variable capacitor.

[0117] When the variable capacitor of the present invention is applied to the balancing method in the above embodiment, the capacitance value of the variable capacitor can be adjusted according to the charge difference between the two batteries to be balanced, thereby adjusting the amount of charge that the variable capacitor can store. Furthermore, the charge balancing can be completed in one go according to the process of the above embodiment, without the need for repeated control of the switch action, thereby effectively improving the efficiency and reliability of battery balancing.

[0118] Optional, reference Figure 6 In one embodiment of the present invention, the peripheral walls of the plurality of electrode sleeves are electrode sheets, and the bottom walls of the plurality of electrode sleeves are insulating sheets.

[0119] In this embodiment, the material of the electrode sheet can be a metal material, such as platinum, gold, titanium, copper, etc., or a non-metallic material, such as graphene, etc., or a mixture of metal and non-metallic materials. The material of the insulating sheet can be ceramic, glass, etc., so that a capacitor is formed between the peripheral wall of each electrode sleeve and the peripheral wall of the adjacent electrode sleeve. During use, by changing the area of ​​each electrode sleeve and the peripheral wall of each electrode sleeve and the peripheral wall of the adjacent electrode sleeve, the capacitance value of the capacitor formed therebetween can be changed, thereby changing the capacitance value of the entire variable capacitor.

[0120] Optionally, referring to 7, in one embodiment of the present invention, the peripheral walls of the plurality of electrode sleeves are insulating sheets, and the bottom walls of the plurality of electrode sleeves are electrode sheets.

[0121] In this embodiment, the material of the electrode sheet can be a metal material, such as platinum, gold, titanium, copper, etc., or a non-metallic material, such as graphene, etc., or a mixture of metal and non-metallic materials. The material of the insulating sheet can be ceramic, glass, etc., so that a capacitor is formed between the bottom wall of each electrode sleeve and the bottom wall of the adjacent electrode sleeve.

[0122] It is understood that, according to the capacitance formula, in order to ensure the distance between the bottom walls, a support sheet 160 is further provided on the side of each lower retaining sheet 130 facing away from the outlet, thereby allowing a certain distance between each bottom wall. During use, by changing the distance between each electrode sleeve and the bottom wall of each electrode sleeve and the bottom wall of the adjacent electrode sleeve, the capacitance value of the capacitor formed therebetween can be changed, thereby changing the capacitance value of the entire variable capacitor.

[0123] Optional, reference Figure 8 In one embodiment of the present invention, the peripheral walls of the plurality of electrode sleeves are electrode sheets, and the bottom walls of the plurality of electrode sleeves are electrode sheets.

[0124] In this embodiment, the electrode sheet can be made of a metal material such as platinum, gold, titanium, copper, or a non-metallic material such as graphene, or a mixture of metal and non-metallic materials. Furthermore, a support sheet 160 is provided on the side of each lower retaining plate 130 facing away from the outlet, thereby allowing a certain distance between each bottom wall. This allows the variable capacitor to have a larger preset maximum capacity.

[0125] refer to Figure 9 The present invention also proposes a battery module for use in electric vehicles. The battery module includes:

[0126] Multiple battery packs, multiple battery packs are connected in series;

[0127] Motor assembly 20;

[0128] Output terminal, the output terminal is used to output voltage to the electric vehicle;

[0129] Charging terminal, which is used to access the charging voltage;

[0130] Equalizing switch assembly;

[0131] Memory 40;

[0132] A processor 50 having a communication terminal for communicating with the electric vehicle;

[0133] a battery module balancing program stored in the memory 40 and executed by the processor 50, wherein the battery module balancing program, when executed by the processor 50, implements any of the above-mentioned battery module balancing methods; and

[0134] A variable capacitor or a variable capacitor as any of the above;

[0135] Among them, the processor 50 is respectively connected to the variable capacitor, the memory 40, the motor assembly 20, the two battery packs and the controlled end of the balancing switch assembly; the motor assembly 20 is driven and connected to the variable capacitor; and the balancing switch assembly is respectively electrically connected to the variable capacitor, the two battery packs, the output end and the charging end.

[0136] In this embodiment, the type of at least one of the multiple battery packs is inconsistent with that of the other battery packs. For example, the number of current battery packs is two, one battery pack is a ternary NCM battery pack, and the other battery pack is a lithium iron phosphate LFP battery pack, so that the battery module can be compatible with a variety of different power usage scenarios; it is understandable that, with reference to Figure 9 The positive electrode of battery pack A11 can be connected to an output terminal (not shown) via a closed switch (controlled by processor 50) to output voltage to the corresponding drive component of the electric vehicle. Similarly, the positive electrode of battery pack A11 can also be connected to a charging terminal via a closed switch (controlled by processor 50), so that an external charging station or the generator inside the electric vehicle can charge the battery packs in the battery module. In addition, in addition to being able to charge in series, multiple battery packs in the battery module can also be charged in parallel through multiple switches.

[0137] In this embodiment, the battery pack has a cell module and a BMS. The BMS can detect various parameters of the cell, such as discharge parameters, charge parameters, reversible capacity, etc., and transmit the above parameters in the form of digital signals, such as I 2 C signal, SPI signal, etc. are output to the processor 50.

[0138] Optionally, the processor 50 may be implemented as an MCU, a DSP (Digital Signal Process), an FPGA (Field Programmable Gate Array), or the like. The processor 50 may be integrated with processing modules such as an ADC detection module, a clock module, and an operation module, so that the processor 50 can detect the voltage value of the variable capacitor. It is understood that the battery module may also include a voltage detection component, which may be implemented using a voltage divider sampling circuit, a voltage detection chip, or the like, to detect the voltage value of the variable capacitor and output a corresponding voltage detection signal to the processor 50, so that the processor 50 can determine the current voltage value of the variable capacitor.

[0139] Optionally, the motor assembly 20 may be a servo motor, an AC motor, etc., so that it can drive the variable capacitor to move under the control of the processor 50, thereby changing the capacitance value of the variable capacitor.

[0140] Optionally, the balancing switch assembly may include multiple switches, and the balancing switch module may, under the control of the processor 50, conduct the path between the variable capacitor and the output terminal or the charging terminal, or connect the variable capacitor to different battery packs in parallel. Figure 9 In the battery module architecture, there are two battery packs. The balancing switch assembly includes a single-pole double-throw switch A 31, a single-pole double-throw switch B 32, a switch A 33, and a switch B 34. When the processor 50 determines that battery pack A 11 and battery pack B 12 require balancing, it controls the operation of the single-pole double-throw switches A 31 and B 32 according to the above-described embodiment to connect the variable capacitor in parallel to the corresponding battery pack with a higher charge. After the variable capacitor is fully charged, the single-pole double-throw switches A 31 and B 32 are controlled to switch the variable capacitor in parallel to the corresponding battery pack with a lower charge. Simultaneously, when the variable capacitor needs to be charged, switch B is controlled to be closed to connect the variable capacitor to the charging terminal. Similarly, when the variable capacitor needs to output a voltage through the output terminal, switch A is controlled to be closed to connect the variable capacitor to the output terminal.

[0141] It is worth noting that because the battery module of the present invention includes all embodiments of the above-mentioned battery module balancing method and / or the above-mentioned battery module balancing method of the variable capacitor, the battery module of the present invention has all the beneficial effects of the above-mentioned battery module balancing method and / or the above-mentioned variable capacitor, which will not be repeated here.

[0142] The present invention also provides an electric vehicle, which includes any one of the battery modules described above.

[0143] It is worth noting that, because the electric vehicle of the present invention includes all embodiments of the above-mentioned battery module, the electric vehicle of the present invention has all the beneficial effects of the above-mentioned battery module, which will not be described in detail here.

[0144] In this embodiment, the electric vehicle's vehicle controller is connected to the communication port of the processor within the battery module to enable data and command interaction between the vehicle controller and the battery module, such as receiving acceleration commands from the vehicle controller. The battery module processor can feed various battery parameters output by the BMS within multiple battery packs back to the vehicle controller.

[0145] The above descriptions are merely optional embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present description and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A variable capacitor, characterized in that: The variable capacitor comprises: A plurality of electrode sleeves, wherein the openings of the plurality of electrode sleeves are in the same direction, and the plurality of electrode sleeves are sequentially sleeved and arranged, and a capacitor is formed between any two of the electrode sleeves; Each electrode sleeve can be relatively far away from or close to its adjacent electrode sleeve along its axial direction to change the capacitance value of the capacitor formed between the two; Among them, in the adjacent electrode sleeves, the lower end of the circumferential wall of the inner electrode sleeve is provided with a lower retaining piece outward along the direction of the bottom wall of the electrode sleeve, and the upper end of the circumferential wall of the outer electrode sleeve is provided with an upper retaining piece inward along the direction of the bottom wall of the electrode sleeve, so that the inner electrode sleeve can overlap with the upper retaining piece of the outer electrode sleeve through the lower retaining piece during the movement to drive the outer electrode sleeve to move.

2. The variable capacitor according to claim 1, wherein One of the adjacent electrode sleeves is a positive electrode sleeve and the other is a negative electrode sleeve. The positive electrode sleeves are connected in parallel to each other, and the negative electrode sleeves are connected in parallel to each other.

3. The variable capacitor according to claim 1, wherein The peripheral walls of the plurality of electrode sleeves are electrode sheets, and the bottom walls of the plurality of electrode sleeves are insulating sheets.

4. The variable capacitor according to claim 1, wherein The peripheral walls of the plurality of electrode sleeves are insulating sheets, and the bottom walls of the plurality of electrode sleeves are electrode sheets.

5. The variable capacitor according to claim 1, wherein The peripheral walls of the plurality of electrode sleeves are electrode sheets, and the bottom walls of the plurality of electrode sleeves are electrode sheets.

6. A battery module balancing method, applied to electric vehicles, characterized in that: The electric vehicle includes a battery module, the battery module includes a plurality of battery packs and a variable capacitor according to any one of claims 1 to 5, and the battery module balancing method includes: Selecting any two battery packs from the plurality of battery packs, obtaining power parameters of the two battery packs, and calculating a power difference between the two battery packs; When the charge difference reaches a preset balanced charge difference, the amount of charge that can be stored in the variable capacitor is infinitely adjusted according to the charge difference, and the variable capacitor is controlled to be connected in parallel with the battery pack with a higher charge to charge the variable capacitor; When it is determined that the variable capacitor is in a fully charged state, the variable capacitor is controlled to disconnect the path between it and the battery pack with higher charge, and is connected in parallel with the battery pack with lower charge to charge the battery pack with lower charge, so that the charge difference between the two battery packs is within a preset balanced charge difference range.

7. The battery module balancing method according to claim 6, wherein: The battery module further includes a motor assembly, and the step of adjusting the capacity value of the variable capacitor according to the power difference is specifically as follows: detecting a voltage value of the battery pack with a higher charge, and calculating a required capacitance value of the variable capacitor according to the voltage value of the battery pack with a higher charge and the charge difference; The motor assembly is controlled to drive the variable capacitor to operate, so that the capacitance value of the variable capacitor is adjusted to the required capacitance value.

8. The battery module balancing method according to claim 6, wherein: The step of determining whether the variable capacitor is in a fully charged state is specifically as follows: detecting a voltage value of the variable capacitor; When it is determined that the voltage value of the variable capacitor remains constant within a preset time period, it is determined that the variable capacitor is in a fully charged state.

9. The battery module balancing method according to claim 6, wherein: The battery module balancing method further includes: Obtaining the current reversible capacity of any of the battery packs, and calculating the attenuation capacity of the battery pack by subtracting the reversible capacity from the design capacity of the corresponding battery pack; When the attenuation capacity of any of the battery packs reaches a preset charging capacity, the battery pack is determined to be in a decaying state, the amount of electricity that the variable capacitor can store is adjusted, and the variable capacitor is controlled to be connected in parallel with the battery pack in the decaying state to compensate for the reversible capacity of the battery pack.

10. The battery module balancing method according to claim 6, wherein the battery module further comprises an output terminal and a charging terminal, wherein: The battery module balancing method further includes: When the power difference does not reach the preset balanced power difference, conducting a path between the variable capacitor and the charging end to charge the variable capacitor; When an acceleration instruction is obtained, the path between the variable capacitor and the charging end is disconnected, and the path between the variable capacitor and the output end is connected, so that the variable capacitor is discharged through the output end.

11. A battery module, used in electric vehicles, characterized in that: The battery module includes: A plurality of battery packs, wherein the plurality of battery packs are sequentially connected in series; Motor components; an output end, the output end being used to output voltage to the electric vehicle; A charging terminal, the charging terminal being used to access a charging voltage; Equalizing switch assembly; Wherein, the battery module further includes: a memory; a processor having a communication terminal for communicating with the electric vehicle; A battery module balancing program stored in the memory and executed by the processor, wherein when the battery module balancing program is executed by the processor, the battery module balancing method according to any one of claims 6 to 10 is implemented; the processor is respectively connected to the variable capacitor, the memory, the motor assembly, the two battery packs, and the controlled end of the balancing switch assembly, the motor assembly is driven and connected to the variable capacitor, and the balancing switch assembly is respectively electrically connected to the variable capacitor, the two battery packs, the output end, and the charging end; or, The battery module includes: a variable capacitor according to any one of claims 1 to 5.

12. The battery module according to claim 11, wherein: The type of at least one of the plurality of battery packs is different from the types of the other battery packs.

13. An electric vehicle, characterized in that: The battery module comprises the battery module according to any one of claims 11 to 12.

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