Power battery active equalization method and system and vehicle

Abstract

The invention relates to the technical field of power batteries of vehicles, in particular to a power battery active equalization method and system and a vehicle, and the method comprises the steps: obtaining the voltage of each single battery of a power battery; according to the voltage of each battery monomer, determining the battery monomer meeting an active equalization condition in each battery monomer; and sequentially conducting loops of the battery monomers meeting the active equalization condition and the storage battery, and equalizing the voltage of each battery monomer through charging and discharging between the storage battery and the battery monomers meeting the active equalization condition. Therefore, the problems of low equalization efficiency caused by complex control circuits and control logics during active equalization of internal single batteries in the prior art are solved; and because the consistency of the single batteries is relatively poor, the service life of the batteries is relatively short, and the like.

Description

Technical Field

[0001] The present application relates to the technical field of power batteries for vehicles, and in particular to a power battery active balancing method, system and vehicle. Background Art

[0002] With the rapid development of the new energy vehicle industry, the demand for power batteries in the automotive field continues to increase; in order to increase the range of new energy vehicles, the number of series and parallel connections of automotive power battery packs has increased accordingly. Therefore, it is particularly important to increase the service life and maximum available capacity of power batteries.

[0003] In the related technology, the consistency of power battery cells can be maintained by balancing the power battery cells, where the balancing methods can be divided into passive balancing and active balancing: passive balancing can discharge the cells with higher voltage through resistance discharge, release electricity in the form of heat, thereby achieving balancing of the entire power battery pack; active balancing can balance through energy transfer, transferring part of the energy of high-energy cells to cells with low energy, thereby achieving balancing of the entire power battery pack.

[0004] However, passive balancing is a resistance energy-consuming balancing, so the set current is generally small and the balancing efficiency is low; active balancing involves the energy transfer between each cell of the power battery, so it involves more working conditions and parameters, the logic of balancing control is more complicated, and the control cost is relatively high. Summary of the invention

[0005] One of the purposes of the present application is to provide a method for active balancing of a power battery, so as to solve the problem in the related art that when the internal cells of the battery are actively balanced, the control circuit and control logic are complex, resulting in low balancing efficiency; and the battery life is short due to the poor consistency of the battery cells; the second purpose is to provide a power battery active balancing system; the third purpose is to provide a vehicle.

[0006] In order to achieve the above purpose, the technical solution adopted in this application is as follows:

[0007] A method for active balancing of a power battery comprises: obtaining the voltage of each battery cell of the power battery; determining the battery cells among the battery cells that meet the active balancing condition according to the voltage of each battery cell; sequentially conducting the circuits of the battery cells that meet the active balancing condition and the storage battery, and balancing the voltages of the battery cells by charging and discharging the storage battery and the battery cells that meet the active balancing condition.

[0008] According to the above technical means, the embodiment of the present application can openly integrate the power battery and the storage battery, use the interaction between the power battery and the storage battery to achieve active balancing, improve the integration level of automobile parts, and reduce the complexity of control logic; and the embodiment of the present application can realize the charging and discharging of the storage battery while realizing the monitoring of the storage battery, using the energy transferred by the power battery during the active balancing process, effectively avoiding the battery feeding and overcharging, improving the reliability of the battery power supply, improving the system safety, and meeting the actual use needs.

[0009] Further, balancing the voltages of the battery cells by charging and discharging the storage battery and the battery cells that meet the active balancing conditions, includes: obtaining the current power of the storage battery; if the current power is less than a first preset power, controlling the battery cells that meet the active balancing conditions to charge the storage battery until the voltages of the battery cells are balanced; if the current power is greater than a second preset power, controlling the storage battery to charge the battery cells that meet the active balancing conditions until the voltages of the battery cells are balanced, wherein the second preset power is greater than the first preset power; otherwise, controlling the charging and discharging of the storage battery and the battery cells that meet the active balancing conditions until the voltages of the battery cells are balanced.

[0010] According to the above technical means, the embodiment of the present application can use the first and second preset powers to compare the current power of the battery, judge the battery status, so as to achieve different controls on the battery, and then complete the active balancing process of the battery and the power battery, balance the voltage of each battery cell, avoid the risk of battery feeding or overcharging, improve the working robustness of the battery and the power battery, and meet actual use needs.

[0011] Further, the control of charging and discharging between the storage battery and the battery cells that meet the active balancing conditions includes: if the current power is greater than or equal to a third preset power, controlling the storage battery to charge the battery cells that meet the active balancing conditions until the balancing of one battery cell voltage is completed, wherein the third preset power is less than the second preset power and greater than the first preset power; if the current power is less than the third preset power, controlling the battery cells that meet the active balancing conditions to charge the storage battery until the balancing of one battery cell voltage is completed; after the balancing of one battery cell voltage is completed, repeating the operation until the balancing of the battery cell voltages is completed.

[0012] According to the above technical means, the embodiment of the present application can use the third preset power to judge the battery power to control the battery to further charge or discharge the power battery, thereby achieving voltage balance of each battery cell, improving the power supply reliability of the battery, and meeting actual use needs.

[0013] Further, before repeating the above operation until the voltages of the battery cells are balanced, it includes: if the current power is less than the first preset power, controlling the battery cells that meet the active balancing condition to charge the storage battery until the voltage of one battery cell is balanced; if the current power is greater than the second preset power, controlling the storage battery to charge the battery cells that meet the active balancing condition until the voltage of one battery cell is balanced.

[0014] According to the above-mentioned technical means, the embodiment of the present application can select cells with excessive pressure difference of the power battery and cells with low voltage of the storage battery to be connected to the circuit in sequence for balanced charging and discharging. In this way, the corresponding battery cells can be operated in order of demand size, avoiding redundancy caused by blind operation. The solution is more intelligent and meets actual usage needs.

[0015] Further, when controlling the battery cells that meet the active balancing condition to charge the storage battery, the battery cells whose voltages among the battery cells that meet the active balancing condition are greater than the average battery cell voltage are used to charge the storage battery; when controlling the storage battery to charge the battery cells that meet the active balancing condition, the battery cells whose voltages among the battery cells that meet the active balancing condition are less than or equal to the average battery cell voltage are charged.

[0016] According to the above-mentioned technical means, the embodiments of the present application can carry out corresponding operations on the battery cells in need in a targeted manner, avoid redundancy caused by blind charging and discharging, improve efficiency and integration level, and meet actual use needs.

[0017] Furthermore, after equalizing the voltages of the battery cells by charging and discharging between the storage battery and the battery cells that meet the active balancing conditions, it also includes: if the current power is less than a first preset power, controlling the power battery to charge the storage battery according to the current difference between the current power and the first preset power; if the current power is greater than a second preset power, controlling the storage battery to charge the power battery according to the current difference between the current power and the second preset power, wherein the second preset power is greater than the first preset power.

[0018] According to the above technical means, the embodiment of the present application can calculate the capacity required for balancing to no power feeding risk based on the current remaining power of the battery, further control the battery power, reduce the battery working risk, improve the low-voltage power supply reliability of the battery, and meet actual use needs.

[0019] Further, determining the battery cell among the battery cells that meets the active balancing condition according to the battery cell voltages includes: calculating an average voltage according to the battery cell voltages; if the voltage difference of the battery cell voltage relative to the average voltage is greater than a preset voltage, the corresponding battery cell meets the active balancing condition.

[0020] According to the above technical means, the embodiment of the present application can determine whether the battery cell meets the active balancing conditions, thereby avoiding blind selection of battery cells to cause charging and discharging redundancy; and because the battery cells that meet the active balancing conditions are screened out for related operations, the consistency of the battery cells can be improved to meet actual usage needs.

[0021] A power battery active equalization system comprises a power battery and a storage battery; a voltage conversion circuit for realizing voltage conversion between the power battery and the storage battery; a collection module for collecting the voltages of each battery cell of the power battery; and an active equalization module for determining the battery cells that meet the active equalization conditions among the battery cells according to the voltages of each battery cell, sequentially conducting the circuits between the battery cells that meet the active equalization conditions and the storage battery, and equalizing the voltages of the battery cells by charging and discharging between the storage battery and the battery cells that meet the active equalization conditions.

[0022] Furthermore, the voltage conversion circuit includes: a first subcircuit, a second subcircuit and a balancing switch component, the first subcircuit includes a first switch component, a second switch component and a first voltage converter, the first subcircuit is used for the power battery to charge the storage battery; the second subcircuit includes a third switch component, a fourth switch component and a second voltage converter, the second subcircuit is used for the storage battery to charge the power battery, wherein the balancing switch component and the first to fourth switch components are each provided with a plurality of switches, and the plurality of switches are used to realize the switching of the positive and negative poles of each power battery during charging and discharging.

[0023] A car comprises the power battery active equalization system as described in the above embodiment.

[0024] Beneficial effects of this application:

[0025] (1) The embodiments of the present application can openly integrate the power battery and the storage battery, and use the interaction between the power battery and the storage battery to achieve active balancing, thereby improving the integration level of automotive components and reducing the complexity of control logic; and the embodiments of the present application can realize the charging and discharging of the storage battery while realizing the monitoring of the storage battery, and effectively avoid the battery feeding and overcharging, improve the reliability of the battery power supply, improve the system safety, and meet the actual use needs;

[0026] (2) The embodiment of the present application can compare the current power of the battery with the first and second preset power levels to determine the battery status, thereby achieving different controls on the battery, and further completing the active balancing process of the battery and the power battery, balancing the voltages of each battery cell, avoiding the risk of battery overcharging or overcharging, and improving the working robustness of the battery and the power battery to meet actual usage needs;

[0027] (3) The embodiment of the present application can use the third preset power to judge the power of the battery, so as to control the battery to further charge or discharge the power battery, thereby achieving the balance of the voltage of each battery cell, improving the power supply reliability of the battery, and meeting the actual use needs;

[0028] (4) In the embodiment of the present application, cells with excessively large voltage differences in the power battery and cells with relatively low voltages in the storage battery can be selected to be connected to the circuit in sequence for balanced charging and discharging. Thus, the corresponding battery cells can be operated in sequence according to the order of demand, thus avoiding redundancy caused by blind operation. The solution is more intelligent and meets the actual use needs.

[0029] (5) The embodiments of the present application can perform corresponding operations on battery cells in need in a targeted manner, avoid redundancy caused by blind charging and discharging, improve efficiency and integration level, and meet actual usage needs;

[0030] (6) The embodiment of the present application can calculate the capacity required to balance to no power supply risk based on the current remaining power of the battery, further control the battery power, reduce the battery working risk, improve the reliability of low-voltage power supply of the battery, and meet actual use needs;

[0031] (7) The embodiments of the present application can determine whether a battery cell meets the active balancing conditions, thereby avoiding blind selection of battery cells that causes charging and discharging redundancy; and because the battery cells that meet the active balancing conditions are screened out for related operations, the consistency of the battery cells can be improved to meet actual usage needs.

[0032] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a flow chart of a method for active equalization of power batteries according to an embodiment of the present application;

[0034] Figure 2 A circuit diagram of an active equalization system for a power battery according to an embodiment of the present application;

[0035] Figure 3 A logical schematic block diagram of active balancing control according to an embodiment of the present application;

[0036] Figure 4 Schematic diagram of an active balancing system for power batteries according to an embodiment of the present application. DETAILED DESCRIPTION

[0037] The following will describe the implementation methods of the present application with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. The present application can also be implemented or applied through other different specific implementation methods, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be understood that the preferred embodiments are only for illustrating the present application, not for limiting the scope of protection of the present application.

[0038] It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present application, and thus the drawings only show components related to the present application rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed at will, and the component layout may also be more complicated.

[0039] With the rapid development of the new energy vehicle industry, the demand for power batteries in the automotive field continues to increase. In order to increase the cruising range of new energy vehicles, the number of series and parallel connections of automotive power battery packs has increased accordingly. However, the consistency of power battery cells is poor, which shortens the battery life and maximum available capacity as the number of charge and discharge cycles increases. In addition, the reduction in the service life and maximum available capacity of power batteries will also aggravate the poor consistency of power battery cells, forming a vicious cycle, which also increases the number of scrapped power batteries year by year. Therefore, maintaining the consistency of power battery cells by balancing the power battery cells is particularly important for increasing the maximum available capacity of power batteries and extending the service life of power batteries.

[0040] In the related technology, balancing methods can be divided into passive balancing and active balancing. Among them, passive balancing can discharge the cells with higher voltage through resistance discharge, release electricity in the form of heat, thereby achieving the balancing of the entire power battery pack, so that all the cell voltages of the power battery pack are maintained within an average range; while active balancing can balance through energy transfer, transferring part of the energy of the high-energy cells to the cells with low energy, thereby achieving the balancing of the entire power battery pack.

[0041] However, passive and active balancing still have some defects:

[0042] (1) From the perspective of balancing efficiency, active balancing is achieved by energy transfer, and there is no heat generation. The balancing current can be increased without affecting heat dissipation, and the balancing efficiency is relatively high. Passive balancing is a resistance energy-consuming balancing method. All consumed energy is released as heat, so a large amount of heat is generated during the balancing process, causing the temperature of the power battery controller to rise. In order to prevent the temperature in the battery pack from being too high and causing thermal safety accidents, the current set for passive balancing is generally small, so the passive balancing efficiency is low.

[0043] (2) From the perspective of balancing cost, the passive balancing circuit is relatively simple, easier to implement, and has a lower cost. Active balancing, on the other hand, involves energy transfer between each cell of the power battery, involves more operating conditions and parameters, and has a more complex logic for balancing control, resulting in a relatively high control cost.

[0044] In addition to the power battery, new energy vehicles also have a 12V battery that can power the low-power systems of the vehicle, such as the vehicle control system, motor control system, and battery management system. The power loss of the 12V battery is inevitable for the vehicle. The power supply of the small battery will cause the vehicle to be unable to start, and the vehicle will not be able to charge the 12V battery. The problem can only be solved by bridging the power of other vehicles with 12V batteries or replacing the 12V battery. In addition, the power supply of the 12V battery will greatly shorten the service life of the small battery and increase the maintenance cost of the vehicle.

[0045] In view of the problems that when active balancing of battery cells is performed in the above-mentioned related technologies, the control circuit and control logic are complex, resulting in low balancing efficiency; and the battery life is short due to poor consistency of battery cells, the present application can propose a method, system and vehicle for active balancing of power batteries.

[0046] Specifically, Figure 1 A schematic diagram of a flow chart of a method for active balancing of power batteries provided in an embodiment of the present application.

[0047] like Figure 1 As shown, the power battery active equalization method includes the following steps:

[0048] In step S101 , the voltage of each battery cell of the power battery is obtained.

[0049] It can be understood that the embodiment of the present application can first collect and obtain the voltage of each battery cell of the power battery; wherein, the embodiment of the present application can use at least one method to obtain the voltage of each battery cell of the power battery, such as using a voltage collection module to periodically collect the voltage of each battery cell.

[0050] In step S102 , a battery cell that meets an active balancing condition is determined among the battery cells according to the voltages of the battery cells.

[0051] It can be understood that, after obtaining the voltage of each battery cell, the embodiment of the present application can use the cell voltage value to determine whether each battery cell meets the active balancing condition; and the battery capacity can be determined according to the battery cell voltage to determine whether the battery has the risk of power feeding and excessive capacity at this time. When there is no risk, the power battery active balancing mode is entered; wherein, the active balancing condition can be set according to the actual situation, and the embodiment of the present application can use the battery cell voltage to determine the battery cells that meet the active balancing condition in at least one way.

[0052] As a possible implementation method, the battery cells among the battery cells that meet the active balancing condition are determined according to the voltages of the battery cells, including: calculating the average voltage according to the voltages of the battery cells; if the voltage difference of the battery cell voltage relative to the average voltage is greater than a preset voltage, the corresponding battery cell meets the active balancing condition.

[0053] The preset voltage can be set according to actual conditions and is not specifically limited thereto.

[0054] It can be understood that the embodiments of the present application can sort the collected battery cell voltages and calculate the average voltage of each battery cell and the cell pressure difference of each battery cell at this time. If the cell pressure difference is small at this time and does not exceed the corresponding preset voltage, it can be considered that the active balancing condition is not met; if the pressure difference is greater than the preset voltage, it can be considered that the active balancing condition is met.

[0055] In step S103, the circuits between the battery cells meeting the active balancing condition and the storage battery are turned on in sequence, and the voltages of the battery cells are balanced by charging and discharging between the storage battery and the battery cells meeting the active balancing condition.

[0056] It can be understood that the power battery pack and the storage battery in the embodiment of the present application are composed of multiple battery cells connected in series, each battery cell has a certain single cell voltage, and they are all numbered from the negative pole and from zero, from small to large; the embodiment of the present application can be set to contain N battery cells connected in series in the power battery pack, and the storage battery can be set to contain M battery cells connected in series; after confirming the battery cells that meet the balancing condition in the above step S102, the embodiment of the present application can sequentially conduct the battery cells that meet the active balancing condition and the circuit between the storage battery, thereby balancing the voltage of each battery cell through charging and discharging between the two; wherein, the embodiment of the present application can control the conduction of the battery cell and the circuit of the storage battery in at least one way, as follows:

[0057] As a possible way to achieve this, Figure 2As shown, in the embodiment of the present application, a balancing switch can be set to realize the conduction control of the battery cell and the battery circuit: in the balancing circuit of the power battery and the battery, each battery cell has a balancing switch on both the positive and negative sides, and the corresponding cell is controlled to be opened and closed by the balancing module, wherein there are N+1 switches on the power battery pack side and M+1 switches on the battery side. The switch numbering method is the same as the cell numbering method, and the specific switches are integrated in two multiple-selection switch modules.

[0058] In the embodiment of the present application, two DCDC converters can be provided to realize a balancing mode with opposite directions of charging and discharging. In the process of realizing the balancing of battery cells, since the input and output ends of the DCDC converter contain positive and negative electrodes, in the actual balancing process, it is necessary to further consider the selection of the balancing circuit for the balancing mode, and also consider the problem of positive and negative electrode switching caused by the positive and negative electrodes of adjacent cells sharing a balancing switch.

[0059] Therefore, the embodiment of the present application can use the voltage acquisition module to output the collected voltage information to the active balancing module; the active balancing module calculates the balancing cell number and balancing mode of the power battery and the 12V battery based on the received voltage information and outputs them to the multiple selection switch module; the multiple selection switch closes the corresponding switch based on the received cell balancing cell number and balancing mode.

[0060] For example, when the multiple selection switch receives the balancing cell number of the power battery and the balancing cell number and balancing mode of the storage battery, which are n, m and balanced discharge respectively, the n-1 and n switches on the power battery side, the m-1 and m switches on the storage battery side and the positive and negative pole switching switches of the balanced discharge circuit are controlled to be closed. Therefore, the embodiment of the present application can use four switches to realize the switching of the positive and negative poles and realize balanced discharge.

[0061] In an embodiment of the present application, the voltages of the battery cells are balanced by charging and discharging between the storage battery and the battery cells that meet the active balancing conditions, including: obtaining the current power of the storage battery; if the current power is less than a first preset power, controlling the battery cells that meet the active balancing conditions to charge the storage battery until the voltages of the battery cells are balanced; if the current power is greater than a second preset power, controlling the storage battery to charge the battery cells that meet the active balancing conditions until the voltages of the battery cells are balanced, wherein the second preset power is greater than the first preset power; otherwise, controlling the charging and discharging between the storage battery and the battery cells that meet the active balancing conditions until the voltages of the battery cells are balanced.

[0062] Wherein, under the premise of ensuring that the second preset power is greater than the first preset power, the first preset power and the second preset power can be set according to actual conditions, and no specific limitation is made to this.

[0063] It can be understood that the embodiments of the present application can set a first preset power level and a second preset power level, and judge the battery power status by comparing the battery power with the preset power level. When the battery power is less than the first preset power level, the battery cells can be controlled to discharge the battery; when the battery power is greater than the second preset power level, the battery can be controlled to charge the battery cells until the voltages of the battery cells are balanced.

[0064] For example, Figure 3 As shown, the embodiment of the present application can determine the battery capacity, set the first preset power to 35% of the full battery charge, and set the second preset power to 85%; when the battery power is lower than 35%, the cells with excessively high power battery cell voltages are selected to discharge the battery in sequence; when the battery power is higher than 85%, the cells with lower power battery cell voltages are selected to supplement power in sequence.

[0065] In an embodiment of the present application, controlling the charging and discharging between a storage battery and a battery cell that meets the active balancing condition includes: if the current power is greater than or equal to a third preset power, controlling the storage battery to charge the battery cell that meets the active balancing condition until the balancing of one battery cell voltage is completed, wherein the third preset power is less than the second preset power and greater than the first preset power; if the current power is less than the third preset power, controlling the battery cell that meets the active balancing condition to charge the storage battery until the balancing of one battery cell voltage is completed; after the balancing of one battery cell voltage is completed, repeating the above operation until the balancing of each battery cell voltage is completed.

[0066] Among them, the third preset power can be set according to actual conditions, and there is no specific limitation on this; the relationship between the first, second and third preset power is: the first preset power is less than the third preset power, and the third preset power is less than the second preset power.

[0067] It can be understood that the embodiment of the present application can perform capacity detection on the battery. When the power level is greater than the third preset power level, it can be considered that the power battery cell needs to be discharged at this time; when the battery capacity is less than the third preset power level, it can be considered that the power battery cell needs to discharge the battery at this time.

[0068] For example, Figure 3 As shown, the third preset power is assumed to be 50% of the full charge of the battery; when the current battery power is greater than 50%, the battery is used to replenish the cells with lower voltages in the power battery cells in sequence; when the power is less than 50%, the cells with too high voltages in the power battery cells are used to discharge the battery in sequence.

[0069] In the embodiment of the present application, before repeating the above operation until the voltages of each battery cell are balanced, it includes: if the current power is less than the first preset power, the battery cells that meet the active balancing conditions are controlled to charge the battery until the voltage of one battery cell is balanced; if the current power is greater than the second preset power, the battery is controlled to charge the battery cells that meet the active balancing conditions until the voltage of one battery cell is balanced.

[0070] It is understandable that the battery cells in the embodiments of the present application can discharge the battery or charge the battery in sequence, that is, after the battery cell completes the operation of the battery cell relative to the battery, the voltage balancing of the next battery cell is performed.

[0071] In the embodiment of the present application, when controlling the battery cells that meet the active balancing conditions to charge the storage battery, the battery cells whose voltages among the battery cells that meet the active balancing conditions are greater than the average battery cell voltages are used to charge the storage battery; when controlling the storage battery to charge the battery cells that meet the active balancing conditions, the battery cells whose voltages among the battery cells that meet the active balancing conditions are less than or equal to the average battery cell voltages are charged.

[0072] Among them, the battery cell voltage average value in the implementation of the present application can be the voltage average value of each battery cell, or it can be the voltage average value of the battery cells that meet the active balancing conditions, and can be calculated and selected according to actual conditions.

[0073] It can be understood that the embodiments of the present application can calculate the voltage mean of the battery cells. When it is necessary to control the battery to charge the battery cells, the battery cells that meet the active balancing conditions are selected, and the battery cells whose voltage is less than or equal to the mean are charged, and the battery cells whose voltage is greater than the mean are not charged; when it is necessary to control the battery cells to charge the battery, the battery cells that meet the active balancing conditions are selected, and the battery cells whose voltage is greater than the mean are charged, and the battery cells whose voltage is less than or equal to the mean are not operated.

[0074] In the embodiment of the present application, after equalizing the voltages of the battery cells by charging and discharging between the storage battery and the battery cells that meet the active balancing conditions, it also includes: if the current power is less than the first preset power, controlling the power battery to charge the storage battery according to the current difference between the current power and the first preset power; if the current power is greater than the second preset power, controlling the storage battery to charge the power battery according to the current difference between the current power and the second preset power, wherein the second preset power is greater than the first preset power.

[0075] It can be understood that after the battery and the battery cells that meet the active balancing conditions are charged and discharged to balance the voltages of each battery cell, the embodiment of the present application can further compare the current battery power with the first and second preset power levels; when the current battery power is less than the first preset power, the difference between the current power and the first preset power is calculated, that is, the power required for balancing to no power feeding risk is calculated based on the current remaining power of the battery, and then the battery is charged according to this difference; when the current battery power is greater than the second preset power, similarly, the difference between the current power and the second preset power is calculated, and the difference is used to enable the battery to charge the power battery.

[0076] The active balancing method of the power battery of the present application will be described below through a specific embodiment. In this embodiment, after judging the battery capacity, there is a risk of over-capacity of power feeding. The embodiment of the present application takes the battery power feeding as an example, and does not elaborate on the situation when the battery power is too large; the details are as follows:

[0077] In the first step, the active balancing module sorts the cells according to the cell voltages of the power batteries collected by the voltage collection module, and calculates the cell pressure difference of each cell of the power battery at this time. If the cell pressure difference is small and does not exceed the corresponding threshold, the third step is entered; if the pressure difference is greater than the corresponding threshold, the next step is entered;

[0078] In the second step, select the cells with excessive voltage difference of the power battery and the cells with lower voltage of the 12V battery and connect them to the circuit in turn to start balanced discharge of the power battery. After the balanced discharge of the cells of the power battery is completed, it is necessary to determine again whether the voltage difference is greater than the threshold. If the condition is still not met, repeat the second step again; otherwise, proceed to the next step.

[0079] The third step is to determine whether there is a risk of low voltage difference in the 12V battery. If there is no risk of power feeding in the battery, the process ends; otherwise, proceed to the next step.

[0080] In the fourth step, the active balancing module calculates the capacity required for balancing to no feeding risk based on the current remaining power of the battery, and calculates the balancing time and capacity required to be evenly distributed to each cell of the power battery. It controls the closure of the switches corresponding to the cells of the power battery and the 12V battery in turn, and starts to replenish the battery. After all cells are balanced, the process ends.

[0081] In summary, the active equalization method for power batteries proposed in the embodiments of the present application has at least the following advantages:

[0082] (1) The embodiments of the present application can openly integrate the power battery and the storage battery, and use the interaction between the power battery and the storage battery to achieve active balancing, thereby improving the integration level of automotive components and reducing the complexity of control logic; and the embodiments of the present application can realize the charging and discharging of the storage battery while realizing the monitoring of the storage battery, and effectively avoid the battery feeding and overcharging, improve the reliability of the battery power supply, improve the system safety, and meet the actual use needs;

[0083] (2) The embodiment of the present application can compare the current power of the battery with the first and second preset power levels to determine the battery status, thereby achieving different controls on the battery, and further completing the active balancing process of the battery and the power battery, balancing the voltages of each battery cell, avoiding the risk of battery overcharging or overcharging, and improving the working robustness of the battery and the power battery to meet actual usage needs;

[0084] (3) The embodiment of the present application can use the third preset power to judge the power of the battery, so as to control the battery to further charge or discharge the power battery, thereby achieving the balance of the voltage of each battery cell, improving the power supply reliability of the battery, and meeting the actual use needs;

[0085] (4) In the embodiment of the present application, cells with excessively large voltage differences in the power battery and cells with relatively low voltages in the storage battery can be selected to be connected to the circuit in sequence for balanced charging and discharging. Thus, the corresponding battery cells can be operated in sequence according to the order of demand, thus avoiding redundancy caused by blind operation. The solution is more intelligent and meets the actual use needs.

[0086] (5) The embodiments of the present application can perform corresponding operations on battery cells in need in a targeted manner, avoid redundancy caused by blind charging and discharging, improve efficiency and integration level, and meet actual usage needs;

[0087] (6) The embodiment of the present application can calculate the capacity required to balance to no power supply risk based on the current remaining power of the battery, further control the battery power, reduce the battery working risk, improve the reliability of low-voltage power supply of the battery, and meet actual use needs;

[0088] (7) The embodiments of the present application can determine whether a battery cell meets the active balancing conditions, thereby avoiding blind selection of battery cells that causes charging and discharging redundancy; and because the battery cells that meet the active balancing conditions are screened out for related operations, the consistency of the battery cells can be improved to meet actual usage needs.

[0089] Next, the active equalization system for power batteries proposed according to the embodiments of the present application will be described with reference to the accompanying drawings.

[0090] Figure 4It is a block diagram of an active equalization system for power batteries according to an embodiment of the present application.

[0091] like Figure 4 As shown, the power battery active equalization system 10 includes: a power battery 100 and a storage battery 200 , a voltage conversion circuit 300 , a collection module 400 and an active equalization module 500 .

[0092] Among them, the voltage conversion circuit 300 is used to realize the voltage conversion of the power battery 100 and the storage battery 200; the acquisition module 400 is used to collect the voltage of each battery cell of the power battery; the active balancing module 500 is used to determine the battery cells that meet the active balancing conditions among the battery cells according to the voltages of each battery cell, and sequentially conduct the circuits between the battery cells that meet the active balancing conditions and the storage battery, and balance the voltages of each battery cell through the charge and discharge between the storage battery and the battery cells that meet the active balancing conditions.

[0093] In the embodiment of the present application, the voltage conversion circuit 300 includes: a first sub-circuit, a second sub-circuit and a balancing switch component, the first sub-circuit includes a first switch component, a second switch component and a first voltage converter, and the first sub-circuit is used for the power battery to charge the storage battery; the second sub-circuit includes a third switch component, a fourth switch component and a second voltage converter, and the second sub-circuit is used for the storage battery to charge the power battery, wherein the balancing switch component and the first to fourth switch components are each provided with a plurality of switches, and the positive and negative poles of each power battery are switched during charging and discharging through the plurality of switches.

[0094] It is understandable that the embodiments of the present application may use Figure 2 The voltage acquisition module shown collects the single cell voltage and total voltage information of the power battery pack and the 12V battery in real time, and outputs the collected information to the active balancing module in real time. The active balancing module calculates the power information of the corresponding single cell by judging the voltage information of the single cell of the power battery pack and the single cell voltage information of the 12V battery, and determines the corresponding balancing mode and the single cell number that needs to be balanced according to the single cell voltage of the power battery and the 12V power. Finally, according to the determined information, the corresponding switch in the multiple selection switch module is controlled to close, so as to realize the balanced charging and discharging of the power battery pack and the 12V battery; in addition, an overcurrent protection resistor is connected in series at the output end of the two DC / DC converters, which can effectively protect the balancing circuit to prevent the power battery and the 12V battery from overcurrent during the active balancing process, which may cause various components in the balancing circuit to burn out; wherein, the power battery and the battery each correspond to a voltage acquisition module.

[0095] Specifically, if Figure 2As shown, the entire active balancing system mainly includes a power battery pack (power battery series-parallel group), a 12V battery group, a power battery voltage acquisition module, a 12V battery voltage acquisition module, an active balancing control module, a charging DC / DC converter, a discharging DC / DC converter, a current limiting resistor and a multi-way selection switch.

[0096] There is one battery cell between adjacent odd-numbered battery cells, and the negative poles of the odd-numbered battery cells are connected in series with the positive poles of the even-numbered battery cells in sequence; the balancing switch assembly includes a power battery balancing switch and a storage battery balancing switch, and the number of power battery balancing switches is one more than the number of battery cells, and the cost is saved by sharing switches, that is, the negative pole switch of the odd-numbered battery cells is reused as the positive pole switch of the even-numbered battery cells, for example, the negative pole switch of the first battery cell is also the positive pole switch of the second battery cell. The storage battery balancing switch includes switches K51 to K55.

[0097] In the first sub-path, the first switch component may include switches K11 to K14, one end of K11 and one end of K13 are connected to the positive electrode and negative electrode of the odd-numbered battery cells in the battery cell sequence, one end of K12 and one end of K14 are connected to the negative electrode and positive electrode of the even-numbered battery cells in the battery cell sequence; the other end of K11 and the other end of K14 are both connected to one end of the input end of the charging DC / DC converter, and the other end of K12 and the other end of K13 are both connected to the other end of the input end of the charging DC / DC converter. The second switch assembly may include switches K21 to K24, one end of K21 and one end of K23 are connected to the positive and negative electrodes of the odd-numbered battery cells in the battery cell sequence of the battery, one end of K22 and one end of K24 are connected to the negative and positive electrodes of the even-numbered battery cells in the battery cell sequence of the battery; the other end of K21 and the other end of K24 are both connected to one end of the output end of the charging DC / DC converter, and the other end of K22 and the other end of K23 are both connected to the other end of the output end of the charging DC / DC converter. Among them, in the first sub-circuit, K21, as the output end of the charging DC / DC converter, is connected in series with an overcurrent protection resistor, which can effectively protect the balancing circuit and prevent the power battery and the 12V battery from overcurrent during the active balancing process, which may cause various components in the balancing circuit to burn out.

[0098] For example, if the positive switch K61 and the negative switch K62 of the first battery cell are both closed, then K11 and K13 are closed, and K21 and K23 are closed; if the positive switch K62 and the negative switch K63 of the second battery cell are both closed, then K12 and K14 are closed.

[0099] In the second sub-path, the third switch component may include switches K31 to K34, one end of K31 and one end of K33 are connected to the positive electrode and negative electrode of the odd-numbered battery cells in the battery cell sequence, one end of K32 and one end of K34 are connected to the negative electrode and positive electrode of the even-numbered battery cells in the battery cell sequence; the other end of K31 and the other end of K34 are both connected to one end of the input end of the discharge DC / DC converter, and the other end of K32 and the other end of K33 are both connected to the other end of the input end of the discharge DC / DC converter. The fourth switch assembly may include switches K41 to K44, one end of K41 and one end of K43 are connected to the positive and negative electrodes of the odd-numbered battery cells in the battery cell sequence, one end of K42 and one end of K44 are connected to the negative and positive electrodes of the even-numbered battery cells in the battery cell sequence; the other end of K41 and the other end of K44 are both connected to one end of the input end of the discharge DC / DC converter, and the other end of K42 and the other end of K43 are both connected to the other end of the input end of the discharge DC / DC converter. Among them, in the second sub-circuit, K41, as the output end of the discharge DC / DC, is connected in series with an overcurrent protection resistor, which can effectively protect the balancing circuit and prevent the power battery and the 12V battery from overcurrent during the active balancing process, which may cause various components in the balancing circuit to burn out.

[0100] For example, if the fifth battery cell positive switch K66 and negative switch K67 are both closed, K31 and K33 are closed, and K41 and K43 are closed; if the sixth battery cell positive switch K67 and negative switch K68 are both closed, K32 and K34 are closed, and K42 and K44 are closed.

[0101] It should be noted that the above explanations of the embodiment of the active equalization method for power batteries are also applicable to the active equalization system for power batteries of this embodiment, and will not be repeated here.

[0102] According to the power battery active balancing system proposed in the embodiment of the present application, the power battery and the storage battery can be integrated in an open manner, and the active balancing can be realized by utilizing the interaction between the power battery and the storage battery, thereby improving the integration level of automobile parts and reducing the complexity of control logic; and the embodiment of the present application can realize the charging and discharging of the storage battery while realizing the monitoring of the storage battery by utilizing the energy transferred by the power battery during the active balancing process, thereby effectively avoiding the battery feeding and overcharging, improving the reliability of the battery power supply, improving the system safety, and meeting the actual use needs.

[0103] An embodiment of the present application also provides a vehicle, comprising the power battery active balancing system as described in the above embodiment.

[0104] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms are not necessarily directed to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0105] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, "N" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0106] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or N executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present application belong.

[0107] It should be understood that the various parts of the present application can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiment, the N steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array, a field programmable gate array, etc.

[0108] A person skilled in the art may understand that all or part of the steps in the method for implementing the above-mentioned embodiment may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment.

[0109] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A method for active equalization of a power battery, characterized in that: The following steps are involved: Obtaining the voltage of each battery cell of the power battery; Determine, according to the voltages of the battery cells, a battery cell among the battery cells that meets an active balancing condition; The circuits of the battery cells meeting the active balancing condition and the storage battery are turned on in sequence, and the voltages of the battery cells are balanced through the mutual charging and discharging between the storage battery and the battery cells meeting the active balancing condition.

2. The active equalization method for power batteries according to claim 1, characterized in that: The step of balancing the voltages of the battery cells by charging and discharging the storage battery and the battery cells that meet the active balancing condition comprises: Obtaining the current power of the battery; If the current power is less than the first preset power, controlling the battery cells that meet the active balancing condition to charge the battery until the voltages of the battery cells are balanced; If the current power is greater than a second preset power, controlling the storage battery to charge the battery cells that meet the active balancing condition until the voltages of the battery cells are balanced, wherein the second preset power is greater than the first preset power; Otherwise, the charging and discharging between the storage battery and the battery cells satisfying the active balancing condition is controlled until the voltages of the battery cells are balanced.

3. The active equalization method for power batteries according to claim 2, characterized in that: The controlling the charging and discharging between the storage battery and the battery cells satisfying the active balancing condition comprises: If the current power is greater than or equal to a third preset power, control the storage battery to charge the battery cells that meet the active balancing condition until the voltage of one battery cell is balanced, wherein the third preset power is less than the second preset power and greater than the first preset power; If the current power is less than the third preset power, controlling the battery cells that meet the active balancing condition to charge the storage battery until the voltage of one battery cell is balanced; After the voltage balancing of one battery cell is completed, the operation is repeated until the voltage balancing of each battery cell is completed.

4. The active equalization method for power batteries according to claim 3, characterized in that: Before repeating the above operation until the voltages of the battery cells are equalized, the method includes: If the current power is less than the first preset power, the battery cells that meet the active balancing condition are controlled to charge the storage battery until the voltage of one battery cell is balanced; If the current power is greater than the second preset power, the storage battery is controlled to charge the battery cells that meet the active balancing condition until the voltage of one battery cell is balanced.

5. The active equalization method for power batteries according to any one of claims 1 to 4, characterized in that: When controlling the battery cells that meet the active balancing condition to charge the storage battery, the battery cells whose voltages are greater than the average battery cell voltages among the battery cells that meet the active balancing condition are used to charge the storage battery; when controlling the storage battery to charge the battery cells that meet the active balancing condition, the battery cells whose voltages are less than or equal to the average battery cell voltages among the battery cells that meet the active balancing condition are charged.

6. The active equalization method for power batteries according to claim 1, characterized in that: After equalizing the voltages of the battery cells by charging and discharging the storage battery and the battery cells that meet the active equalization condition, the method further includes: If the current power is less than the first preset power, controlling the power battery to charge the storage battery according to the current difference between the current power and the first preset power; If the current power is greater than a second preset power, the storage battery is controlled to charge the power battery according to a current difference between the current power and the second preset power, wherein the second preset power is greater than the first preset power.

7. The active equalization method for power batteries according to claim 1, characterized in that: The step of determining the battery cells among the battery cells that meet the active balancing condition according to the voltages of the battery cells comprises: Calculating an average voltage according to the voltages of the battery cells; If the voltage difference of the battery cell voltage relative to the average voltage is greater than a preset voltage, the corresponding battery cell meets the active balancing condition.

8. A power battery active equalization system, characterized in that: include: Power batteries and storage batteries; A voltage conversion circuit, used to realize voltage conversion between the power battery and the storage battery; A collection module, used for collecting the voltage of each battery cell of the power battery; The active balancing module is used to determine the battery cells that meet the active balancing conditions among the battery cells according to the voltages of the battery cells, sequentially connect the circuits of the battery cells that meet the active balancing conditions and the storage battery, and balance the voltages of the battery cells by charging and discharging the storage battery and the battery cells that meet the active balancing conditions.

9. The power battery active equalization system according to claim 8, characterized in that: The voltage conversion circuit comprises: A first subcircuit, a second subcircuit and a balancing switch component, wherein the first subcircuit includes a first switch component, a second switch component and a first voltage converter, and the first subcircuit is used for the power battery to charge the storage battery; the second subcircuit includes a third switch component, a fourth switch component and a second voltage converter, and the second subcircuit is used for the storage battery to charge the power battery, wherein: The balancing switch assembly and the first to fourth switch assemblies are each provided with a plurality of switches, through which the positive and negative poles of each power battery are switched during charging and discharging.

10. A vehicle, characterized in that: It comprises the power battery active equalization system as described in claim 8 or 9.

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