Online efficient bidirectional active balancing method for in-service power batteries for vehicles

Abstract

The present application discloses an online efficient bidirectional active balancing method for in-service power batteries for vehicles, comprising the following steps: grouping a number of single cells, configuring a first active balancing module in each group, configuring a second active balancing module between adjacent groups, the second active balancing module being used for inter-group balancing control; obtaining voltage information, current information, cell sequence number and temperature information of all single cells; the first active balancing module performs balancing control on the single cells in the group. The advantage of the present application is that by carrying out online bidirectional active balancing technology, the full and reasonable utilization of single cells, the extension of battery pack service life and the improvement of vehicle operation efficiency can be achieved, and it has important theoretical research significance and engineering application value.

Description

Technical Field

[0001] The present application relates to the technical field of power batteries, and in particular to an online efficient bidirectional active balancing method for in-service power batteries for vehicles. Background Art

[0002] In recent years, electric vehicles have become more and more popular in the market, but the battery life and charging issues of electric vehicles are still the pain points of the industry. After long-term use of power batteries, the internal resistance of the battery increases, the battery capacity decreases, and the battery pack's mileage shortens; the differences between monomers become more and more obvious, causing a vicious cycle, accelerating the decline of battery performance, which will seriously affect the safe use of power battery packs and have to be retired; in addition, the cost of replacing new batteries is very high. Therefore, for in-service power batteries for vehicles, how to improve and ensure the battery pack's mileage is imminent. Summary of the invention

[0003] The present application provides an online high-efficiency bidirectional active balancing method for in-service automotive power batteries. The advantage of the method is that by implementing online bidirectional active balancing technology, the goals of fully and rationally utilizing single cells, extending the service life of the battery pack, and improving the operating efficiency of the entire vehicle can be achieved. The method has important theoretical research significance and engineering application value.

[0004] In a first aspect, the present application provides an online efficient bidirectional active balancing method for an in-service power battery for a vehicle, characterized in that it comprises the following steps:

[0005] Grouping a number of single cells, configuring a first active balancing module in each group, configuring a second active balancing module between adjacent groups, and the second active balancing module is used for balancing control between groups;

[0006] Obtain the voltage information, current information, cell serial number and temperature information of all single cells;

[0007] The first active balancing module performs balancing control on the single cells in the group according to the following strategy:

[0008] If the system SOC range is 0% to 10% or 90% to 100%, the balancing indicator is the terminal voltage; the cells in the battery pack are sorted according to the terminal voltage and paired, and the i-th cell pair is represented as L is the total number of cells in the battery pack; when sorted in descending order, the number of cells right When sorting in ascending order, the monomer right Charging;

[0009] If the system SOC range is 10% to 90%, the balancing index is SOC; sort the cells in the battery pack according to the SOC size and pair them, and record the jth pair as When sorting in descending order, the monomer right When sorting in ascending order, the monomer right to charge.

[0010] Furthermore, the method further comprises the step of regularly updating the pairing information of the single cells according to the obtained voltage information, current information, cell serial number and temperature information of the single cells in the group.

[0011] Furthermore, the method further comprises the steps of obtaining a balanced current by using a staggered pulsating current control strategy, including the following specific steps:

[0012] Step 1: Divide the balancing current into multiple levels;

[0013] Step 2: Calculate the battery pack inconsistency factor and define the series battery pack inconsistency factor:

[0014]

[0015] In the formula, σ i represents the inconsistency between the single cells in the ith battery pack, x represents the state of the single cell, including the single cell SOC and terminal voltage, is the mean value, L is the total number of cells in the battery pack; if the system SOC range is 0% to 10% or 90% to 100%, x is the cell terminal voltage; otherwise, x is the cell SOC;

[0016] When the inconsistency factor is less than a set value, repeat Step 2; otherwise, start the balancing task and complete the pairing of the cells in the battery pack;

[0017] Step 3: Adjust the balancing current level in stages according to the inconsistency factor of the battery pack;

[0018] Step 4: According to the size of the battery pack inconsistency factor, adjust the balanced pulse width T of each monomer pair k , in represents the rounding down function; the equalized pulse width T k The design is as follows:

[0019] T k =λ k T0

[0020] In the formula, T0 is the initial design value, λ k is the attenuation coefficient and satisfies As the balancing effect becomes more obvious, when the battery pack inconsistency factor is lower than a certain threshold, the balancing pulse widths of each pair of cells tend to be consistent, that is,

[0021] Step 5: When the active balancing condition is met, the terminals are arranged in descending order according to the terminal voltage difference or SOC difference, and the physical links of one or more monomer pairs are connected in sequence for energy transfer; when the last monomer pair is balanced, the duration is recorded as an active balancing cycle; when one or several monomer pairs meet the balance cutoff condition, the corresponding physical link is disconnected;

[0022] Step 6: Repeat Step 2–Step 5 to precisely control the energy transfer of the monomer pair.

[0023] Furthermore, the method also includes the following steps: over-temperature detection, real-time collection of battery pack temperature information, and when it is detected that the temperature threshold is exceeded for multiple consecutive times, the active balancing task is suspended, and a corresponding over-voltage warning is given, and the power is automatically cut off when the over-temperature is serious.

[0024] Furthermore, the method also includes the following steps: overcurrent detection, in the process of active balancing, real-time collection of current information of each balancing branch, when monitoring that the current threshold is exceeded for multiple consecutive times, suspending the active balancing task, giving a corresponding overcurrent warning, and actively cutting off the power when the overcurrent is serious.

[0025] Furthermore, the method also includes the following steps: overcharge and over-discharge monitoring: during vehicle charging, energy is transferred preferentially to cells that have reached the highest cut-off voltage, and a suspected overcharge warning is given; during vehicle discharging, energy is replenished preferentially to cells that have reached the lowest cut-off voltage, and a suspected over-discharge warning is given.

[0026] In a second aspect, the present application provides an electronic device, including a memory and a processor, wherein the memory stores a computer program, and when the computer program is called and executed by the processor, the method described above is implemented.

[0027] In a third aspect, the present application provides a computer-readable medium, in which a computer program is stored. When the computer program is called and executed by a processor, the method described above is implemented.

[0028] In summary, the beneficial effects of the present application are as follows: This application focuses on the problem of the "barrel effect" of the battery pack, and by developing online bidirectional active balancing technology, it achieves the goals of full and reasonable utilization of single cells, extending the service life of the battery pack, and improving the operating efficiency of the entire vehicle. It has important theoretical research significance and engineering application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1This is a schematic diagram of the topology of a power battery balancing network in a specific implementation manner of the present application;

[0030] Figure 2 It is a schematic diagram of an active balancing cycle in a specific implementation manner of the present application. DETAILED DESCRIPTION

[0031] The specific implementation of the present application is described in detail below with reference to the accompanying drawings.

[0032] In a specific embodiment of the present application, an online efficient bidirectional active balancing method for an in-service power battery for a vehicle is provided, comprising the following steps:

[0033] refer to Figure 1 , several single cells are grouped, and a first active balancing module (i.e. Figure 1 Active balancing module S_1#, active balancing module S_2#), configure the second active balancing module (i.e. Figure 1 The active balancing module M_1# in the example, the second active balancing module is used for inter-group balancing control; Figure 1 Each active balancing module in the inner layer can connect 2n single cells to realize the real-time collection of battery voltage, current data, and temperature data, and then decide whether to start the single cell balancing task in the group according to the balancing judgment mark. The outer active balancing module can realize fast balancing between groups and manage the inner active balancing modules.

[0034] Active battery balancing technology uses the terminal voltage, capacity or SOC of a single cell as a balancing indicator, and realizes the transfer of energy between single cells through components such as resistors, inductors, capacitors and transformers, so as to achieve the purpose of reducing the inconsistency of battery pack capacity.

[0035] Obtain the voltage information, current information, cell serial number and temperature information of all single cells;

[0036] The first active balancing module performs balancing control on the single cells in the group according to the following strategy:

[0037] If the system SOC range is 0% to 10% or 90% to 100%, the balancing indicator is the terminal voltage; the cells in the battery pack are sorted according to the terminal voltage and paired, and the i-th cell pair is represented as L is the total number of cells in the battery pack; when sorted in descending order, the number of cells right When sorting in ascending order, the monomer right Charging;

[0038] If the system SOC range is 10% to 90%, the balancing index is SOC; sort the cells in the battery pack according to the SOC size and pair them, and record the jth pair as When sorting in descending order, the monomer right When sorting in ascending order, the monomer right to charge.

[0039] The pairing information of the single cells is updated regularly according to the obtained voltage information, current information, single cell serial number and temperature information of the single cells in the group.

[0040] Balancing current control is a very complex nonlinear control problem. In engineering applications, it is often difficult to ensure reliability by adaptively adjusting the balancing current according to the vehicle operating conditions. If the balancing current decision value is too large, it will cause certain damage to the performance of low-capacity cells, while if the decision value is too small, it will slow down the balancing speed.

[0041] Considering that the energy transfer between cells during the balancing process will generate a certain amount of heat, staggered pulsating charging and discharging is adopted to ensure that each cell can operate within a suitable temperature range to improve battery performance, service life and safety. To this end, considering the application requirements of battery thermal management, safety protection and active balancing speed, a staggered pulsating current control strategy is designed for the inner balancing network topology. The specific steps are as follows:

[0042] Step 1: Divide the balancing current into multiple levels;

[0043] Step 2: Calculate the battery pack inconsistency factor and define the series battery pack inconsistency factor:

[0044]

[0045] In the formula, σ i represents the inconsistency between the single cells in the ith battery pack, x represents the state of the single cell, including the single cell SOC and terminal voltage, is the mean value, L is the total number of cells in the battery pack; if the system SOC range is 0% to 10% or 90% to 100%, x is the cell terminal voltage; otherwise, x is the cell SOC;

[0046] When the inconsistency factor is less than a set value, repeat Step 2; otherwise, start the balancing task and complete the pairing of the cells in the battery pack;

[0047] Step 3: Adjust the balancing current level in stages according to the inconsistency factor of the battery pack;

[0048] Step 4: According to the size of the battery pack inconsistency factor, adjust the balanced pulse width T of each monomer pair k , in represents the rounding down function; the equalized pulse width T k The design is as follows:

[0049] T k =λ k T0

[0050] In the formula, T0 is the initial design value, λ k is the attenuation coefficient and satisfies As the balancing effect becomes more obvious, when the battery pack inconsistency factor is lower than a certain threshold, the balancing pulse widths of each pair of cells tend to be consistent, that is,

[0051] Step 5: When the active balancing conditions are met, the terminals are arranged in descending order according to the terminal voltage range or SOC range. Figure 2 , connect one or more physical links of monomer pairs in turn to transfer energy; when the last monomer pair is balanced, the duration is recorded as an active balance cycle; when one or several monomer pairs meet the balance cutoff condition, disconnect the corresponding physical link;

[0052] Step 6: Repeat Step 2–Step 5 to precisely control the energy transfer of the monomer pair and achieve lossless and efficient balance.

[0053] It also includes the following steps: over-temperature detection, real-time collection of battery pack temperature information, when it is detected that the temperature threshold is exceeded for multiple consecutive times, the active balancing task is suspended, and a corresponding over-voltage warning is given, and the power is automatically cut off when the over-temperature is serious.

[0054] It also includes the following steps: overcurrent detection. During the active balancing process, the current information of each balancing branch is collected in real time. When it is monitored that the current threshold is exceeded for multiple consecutive times, the active balancing task is suspended, and a corresponding overcurrent warning is given. In addition, the power will be automatically cut off when the overcurrent is serious.

[0055] The method also includes the following steps: overcharge and over-discharge monitoring. During vehicle charging, energy is transferred to cells that have reached the highest cut-off voltage first, and a suspected overcharge warning is given. During vehicle discharging, energy is replenished to cells that have reached the lowest cut-off voltage first, and a suspected over-discharge warning is given.

[0056] The safety of the balancing process is improved through self-protection mechanisms such as over-temperature detection, over-current detection, and over-charge and over-discharge monitoring.

[0057] In a specific embodiment of the present application, an electronic device is provided, including a memory and a processor, wherein a computer program is stored in the memory, and when the computer program is called and executed by the processor, an online high-efficiency bidirectional active balancing method for in-service power batteries for vehicles as described above is implemented.

[0058] In a specific embodiment of the present application, a computer-readable medium is provided, in which a computer program is stored. When the computer program is called and executed by a processor, an online high-efficiency bidirectional active balancing method for in-service power batteries for vehicles as described above is implemented.

[0059] The above is only a preferred implementation of the present application. It should be pointed out that a person skilled in the art can make several modifications and improvements without departing from the inventive concept of the present application, and these all fall within the scope of protection of the present application.

Claims

1. An online high-efficiency bidirectional active balancing method for in-service power batteries for vehicles, characterized in that: The following steps are involved: Grouping a number of single cells, configuring a first active balancing module in each group, configuring a second active balancing module between adjacent groups, and the second active balancing module is used for balancing control between groups; Obtain the voltage information, current information, cell serial number and temperature information of all single cells; The first active balancing module performs balancing control on the single cells in the group according to the following strategy: If the system SOC range is 0% to 10% or 90% to 100%, the balancing indicator is the terminal voltage; the cells in the battery pack are sorted according to the terminal voltage and paired, and the i-th cell pair is represented as L is the total number of cells in the battery pack; when sorted in descending order, the number of cells right When sorting in ascending order, the monomer right Charging; If the system SOC range is 10% to 90%, the balancing index is SOC; sort the cells in the battery pack according to the SOC size and pair them, and record the jth pair as When sorting in descending order, the monomer right When sorting in ascending order, the monomer right Charging; The method also includes the steps of obtaining a balanced current by using a staggered pulsating current control strategy, including the following specific steps: Step 1: Divide the balancing current into multiple levels; Step 2: Calculate the battery pack inconsistency factor and define the series battery pack inconsistency factor: In the formula, σ i represents the inconsistency between the single cells in the ith battery pack, x represents the state of the single cell, including the single cell SOC and terminal voltage, is the mean value, L is the total number of cells in the battery pack; if the system SOC range is 0% to 10% or 90% to 100%, x is the cell terminal voltage; otherwise, x is the cell SOC; When the inconsistency factor is less than a set value, repeat Step 2; otherwise, start the balancing task and complete the pairing of the cells in the battery pack; Step 3: Adjust the balancing current level in stages according to the inconsistency factor of the battery pack; Step 4: According to the size of the battery pack inconsistency factor, adjust the balanced pulse width T of each monomer pair k , in represents the rounding down function; the equalized pulse width T k The design is as follows: T k =λ k T0 In the formula, T0 is the initial design value, λ k is the attenuation coefficient and satisfies As the balancing effect becomes more obvious, when the battery pack inconsistency factor is lower than a certain threshold, the balancing pulse widths of each pair of cells tend to be consistent, that is, Step 5: When the active balancing condition is met, the cells are arranged in descending order according to the terminal voltage difference or SOC difference, and the physical links of one or more cell pairs are connected in sequence for energy transfer; When the last monomer pair is balanced, the duration is recorded as an active balance cycle; when one or several monomer pairs meet the balance cutoff condition, the corresponding physical link is disconnected; Step 6: Repeat Step 2–Step 5 to precisely control the energy transfer of the monomer pair.

2. The online high-efficiency bidirectional active balancing method for in-service power batteries for vehicles according to claim 1 is characterized in that: The method further includes the step of regularly updating the pairing information of the single cells according to the obtained voltage information, current information, single cell serial number and temperature information of the single cells in the group.

3. The online high-efficiency bidirectional active balancing method for in-service power batteries for vehicles according to claim 1 is characterized in that: It also includes the following steps: over-temperature detection, real-time collection of battery pack temperature information, when it is detected that the temperature threshold is exceeded for multiple consecutive times, the active balancing task is suspended, and a corresponding over-voltage warning is given, and the power is automatically cut off when the over-temperature is serious.

4. The online high-efficiency bidirectional active balancing method for in-service power batteries for vehicles according to claim 1 is characterized in that: It also includes the following steps: overcurrent detection. During the active balancing process, the current information of each balancing branch is collected in real time. When it is monitored that the current threshold is exceeded for multiple consecutive times, the active balancing task is suspended, and a corresponding overcurrent warning is given. In addition, the power will be automatically cut off when the overcurrent is serious.

5. The online high-efficiency bidirectional active balancing method for in-service power batteries for vehicles according to claim 1 is characterized in that: The method also includes the following steps: overcharge and over-discharge monitoring. During vehicle charging, energy is transferred to cells that have reached the highest cut-off voltage first, and a suspected overcharge warning is given. During vehicle discharging, energy is replenished to cells that have reached the lowest cut-off voltage first, and a suspected over-discharge warning is given.

6. An electronic device, characterized in that: The method comprises a memory and a processor, wherein a computer program is stored in the memory, and when the computer program is called and executed by the processor, the method according to any one of claims 1 to 5 is implemented.

7. A computer-readable medium, characterized in that The computer readable medium stores a computer program, and when the computer program is called and executed by a processor, the method according to any one of claims 1 to 5 is implemented.

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