Assembled battery equalization control method based on coupling inductor

Abstract

The invention provides an assembled battery equalization control method based on coupling inductors. According to the method, a battery module is used as a research object, and a coupling inductance battery equalization model is built; the battery module is composed of a plurality of single batteries, and the single batteries are numbered as 1, 2, 3,..., 2n-1 and 2n; n is a positive integer; the method comprises the following steps: acquiring a real-time SOC (State of Charge) of each single battery through a switch control unit; calculating an SOC range value delta all (k) of the battery module according to the real-time SOC; determining whether to start a circuit corresponding to the equalization model or not according to the delta all (k); when it is determined that the circuit corresponding to the equalization model is started, the next step is executed; determining a charge state reference value SOCref (k) according to the real-time SOC and the parity of the serial number of each single battery, and then calculating a strategy selection reference value delta ref (k) of the battery module in real time; determining to adopt an extreme value method equalization strategy or an odd-even method equalization strategy according to the delta ref (k); and carrying out SOC equalization on the single batteries by adopting an assembled battery equalization control method in which an extreme value method equalization strategy and an odd-even method equalization strategy are coupled. According to the invention, through a combined balance control method combining an odd-even method strategy and an extreme value method, more single batteries participate in an energy transfer process at the same time, so that the balance efficiency is greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of battery balancing control, and in particular to a combined battery balancing control method based on coupled inductors. Background Art

[0002] In the energy storage system, battery modules are connected in series and parallel to meet specific voltage and capacity requirements. However, due to performance differences between single cells, such as the "barrel effect", the battery parameters within the module are inconsistent, which affects the safety of the battery module. Existing battery balancing technology faces problems such as slow balancing speed and high energy loss rate. The current balancing strategy mainly uses the extreme value method, which can only balance the energy of the batteries with the highest and lowest state of charge (SOC), while other batteries fail to participate, resulting in low balancing efficiency.

[0003] To this end, we need to develop a new battery balancing control strategy to enable more batteries to participate in energy transfer at the same time, improve the balancing efficiency and the flexibility of battery energy balancing control. Summary of the invention

[0004] The present invention aims to provide a battery balancing control method, which aims to solve the problem that the balancing efficiency of the existing battery balancing circuit is low when the number of battery groups is large, so as to achieve the purpose of allowing more single cells to participate in the balancing charge and discharge process within a balancing cycle, thereby greatly improving the balancing speed.

[0005] Therefore, the purpose of the present invention is to provide a combined battery balancing control method based on coupled inductors.

[0006] In order to achieve the above-mentioned purpose, the technical solution of the present invention provides a combined battery balancing control method based on coupled inductors, the control method takes a battery module as a research object, and builds a coupled inductor battery balancing model; the battery module is composed of a plurality of single cells, and the plurality of single cells are numbered 1, 2, 3, ..., 2n-1, 2n; n is a positive integer; the control method comprises: step S1: obtaining the real-time SOC of each single cell through a switch control unit; step S2: calculating the SOC extreme value Δ of the battery module according to the real-time SOC of each single cell _all (k); Step S3: according to the SOC extreme difference value Δ of the battery module _all (k), determining whether to turn on the circuit corresponding to the coupled inductor battery balancing model; when it is determined to turn on the circuit corresponding to the coupled inductor battery balancing model, executing step S4; step S4: determining a charge state reference value S according to the real-time SOC of each single cell and the parity of the number corresponding to each single cell OC_ref(k), and then calculate the strategy selection reference value Δ of the battery module in real time _ref (k); Step S5: Selecting a reference value Δ according to the strategy of the battery module _ref (k), determine to adopt the extreme value method balancing strategy or the odd-even method balancing strategy; step S6: adopt the combined battery balancing control method that couples the extreme value method balancing strategy with the odd-even method balancing strategy to balance the SOC of the single battery.

[0007] Preferably, obtaining the real-time state of charge of each single cell in step S1 is specifically as follows: obtaining the SOC of each single cell in the battery module at every specified period through the switch control unit, and executing the balancing control strategy; after each single cell executes this round of balancing control strategy, the SOC of each single cell will change; when executing the next period, obtaining the SOC of each single cell in the battery module again through the switch control unit, and reselecting the balancing strategy for balancing control.

[0008] Preferably, the SOC extreme value Δ of the battery module _all The expression of (k) is:

[0009] Δ _all (k) = S oc_max (k)-S oc_min (k)(1)

[0010] In formula (1), Δ _all (k) is the equilibrium reference value at time k; S OC_max (k) is the maximum SOC value of each single cell in the battery module at time k; S OC_min (k) is the minimum SOC value of each single cell in the battery module at time k.

[0011] Preferably, in step S3, the process of determining whether to start the circuit corresponding to the coupled inductor battery balancing model is expressed as follows:

[0012]

[0013] In formula (2), α is the equilibrium start threshold.

[0014] Preferably, in step S4, a charge state reference value S is determined. OC_ref The process of (k) is expressed as:

[0015]

[0016] In formula (3), x is the battery number corresponding to the single battery with the smallest SOC in the battery module at time k; S OCmin_奇 (k) is the minimum SOC value of all odd-numbered cells in the battery module at time k; SOCmin_偶 (k) is the minimum SOC value of all even-numbered cells in the battery module at time k;

[0017] In step S4, the strategy selection reference value Δ of the battery module is calculated in real time. _ref The process of (k) is expressed as:

[0018] Δ _ref (k) = S OC_ref (k)-S OC_min (k)(4)

[0019] In formula (4), Δ _ref (k) is the strategy selection reference value of the battery module at time k; S OC_ref (k) is the charge state reference value at time k; S OC_min (k) is the minimum SOC value of all cells in the battery module at time k.

[0020] Preferably, in step S5, the process of selecting to adopt the extreme value method balancing strategy or the even-odd method balancing strategy is expressed as follows:

[0021]

[0022] In formula (5), β is the strategy selection threshold.

[0023] Preferably, the circuit corresponding to the coupled inductor battery balancing model specifically includes: a first balancing switch unit, a second balancing switch unit, ..., a (2n-1)th balancing switch unit, a 2nth balancing switch unit, an active balancing unit and a battery module connected in series; wherein each balancing switch unit is composed of a first switch S connected in series. d and the second switch S c The active balancing unit is composed of a coupled inductor with a 2n winding; the battery module is composed of 2n single cells B connected in series _1 , B _2 ,……,B _2n-1 and B _2n The first switch S of each balancing switch unit is constituted; d The negative electrode of the second switch S c The negative electrode of the (2m-1)th balancing switch unit is connected to the second switch S c_2m-1 The positive electrode is connected to the single battery B through a wire _2m-1 The positive electrode of the (2m-1)th balancing switch unit is connected to the first switch S d_2m-1 The positive pole of the coupled inductor is connected through a winding L _m With single battery B _2m-1 The negative electrode of the second switch S of the 2mth balancing switch unit is connected;c_2m The positive pole of the coupled inductor is connected through a winding L _m With single battery B _2m The positive electrode of the first switch S of the 2mth balancing switch unit is connected. d_2m The positive electrode is connected to the single battery B through a wire _2m The negative pole of the coupled inductor is connected; wherein n represents the total number of windings of the coupled inductor; m represents the serial number of a winding of the coupled inductor, and m∈[1,n].

[0024] Preferably, in step S6, the process of using the extreme value method balancing strategy to balance the SOC of the single battery is specifically as follows: when the extreme value method balancing strategy is used for balancing, if the single battery B in the battery module _u The SOC value of single battery B is the highest. _v When the SOC value of is the lowest and the parity of the two single battery numbers is different, the working state of the balancing switch unit is:

[0025]

[0026] In formula (6), S d_u is the uth first switch; S c_v is the vth second switch; T1 is the charging cycle of the active balancing unit; T is a balancing cycle; t is the balancing time;

[0027] If the single battery B in the battery module _u The SOC value of single battery B is the highest. _v The SOC value of the battery is the lowest, and the parity of the two battery numbers is the same, the definition is the same as that of the battery B _u Adjacent single cell B _w is a hub battery; then the working state of the balancing switch unit is:

[0028]

[0029] In formula (7), S d_w is the wth first switch; S c_w is the wth second switch.

[0030] Preferably, in step S6, the process of using the odd-even method to balance the SOC of the single battery is as follows: when the odd-even method is used to balance, if the single battery B with an odd number in the battery module _v The SOC value of is the lowest, then the working state of the balancing switch unit is:

[0031]

[0032] In formula (8), Sd_2、4……2n is the first switch of all even-numbered single cells; T1 is the charging cycle of the active balancing unit; T is a balancing cycle; t is the balancing time;

[0033] When the odd-even balancing strategy is used for balancing, if the single battery B in the battery module is even-numbered _v The SOC value of is the lowest, then the working state of the balancing switch unit is:

[0034]

[0035] In formula (9), S d_1、3……2n-1 The first switch for all odd-numbered cells.

[0036] Beneficial effects of the present invention:

[0037] The coupled inductor-based combined battery balancing control method provided by the present invention is suitable for the coupled inductor battery balancing model constructed. Specifically, through the combined balancing control method combining the odd-even strategy with the extreme value method, more single cells can participate in the energy transfer process at the same time, thereby greatly improving the balancing efficiency.

[0038] Additional aspects and advantages of the invention will become apparent from the following description, or may be learned by practice of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 A schematic diagram showing a flow chart of a combined battery balancing control method based on coupled inductors according to an embodiment of the present invention;

[0040] Figure 2 A circuit schematic diagram corresponding to a coupled inductor battery balancing model constructed according to an embodiment of the present invention is shown;

[0041] Figure 3 A schematic diagram showing the SOC and balancing time of each single battery when a commonly used balancing solution is adopted according to an embodiment of the present invention;

[0042] Figure 4 A schematic diagram of the SOC and balancing time of each single battery when a combined battery balancing control method based on coupled inductors is adopted according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0043] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, Figures 1 to 3 As shown, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementations. It should be noted that, in the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other.

[0044] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0045] Figure 1 FIG. 1 is a flow chart of a method for controlling a combined battery balance based on coupled inductors according to an embodiment of the present invention. Figure 1 As shown, steps S1 to S5 of the control method are a balancing strategy selection process, which respectively include using an extreme value balancing strategy, using an odd-even balancing strategy, and imbalance. The implementation steps of the control method are as follows:

[0046] Step S1: obtain the real-time SOC of each single cell through the switch control unit; the real-time state of charge of each single cell in step S1 is specifically as follows: obtain the SOC of each single cell in the battery module through the switch control unit at every specified period, and execute the balancing control strategy; after each single cell executes this round of balancing control strategy, the SOC of each single cell will change; when executing the next cycle, obtain the SOC of each single cell in the battery module again through the switch control unit, and reselect the balancing strategy for balancing control.

[0047] Step S2: Calculate the SOC extreme value Δ of the battery module according to the real-time SOC of each single battery _all (k); SOC extreme value Δ of the battery module _all The expression of (k) is:

[0048] Δ _all (k) = S oc_max (k)-S oc_min (k)(1)

[0049] In formula (1), Δ _all (k) is the equilibrium reference value at time k; S OC_max (k) is the maximum SOC value of each single cell in the battery module at time k; S OC_min (k) is the minimum SOC value of each single cell in the battery module at time k.

[0050] Step S3: According to the SOC extreme difference value Δ of the battery module _all (k), determining whether to turn on the circuit corresponding to the coupled inductor battery balancing model; when it is determined that the circuit corresponding to the coupled inductor battery balancing model is turned on, executing step S4; otherwise, directly ending the operation of the coupled inductor-based combined battery balancing control method; in step S3, the process of determining whether to turn on the circuit corresponding to the coupled inductor battery balancing model is expressed as follows:

[0051]

[0052] In formula (2), α is the equilibrium start threshold.

[0053] Step S4: Determine the charge state reference value S according to the real-time SOC of each single cell and the parity of the number corresponding to each single cell. OC_ref (k), and then calculate the strategy selection reference value Δ of the battery module in real time _ref (k); In step S4, determine the charge state reference value S OC_ref The process of (k) is expressed as:

[0054]

[0055] In formula (3), x is the battery number corresponding to the single battery with the smallest SOC in the battery module at time k; S OCmin_奇 (k) is the minimum SOC value of all odd-numbered cells in the battery module at time k; S OCmin_偶 (k) is the minimum SOC value of all even-numbered cells in the battery module at time k;

[0056] In step S4, the strategy selection reference value Δ of the battery module is calculated in real time. _ref The process of (k) is expressed as:

[0057] Δ _ref (k) = S OC_ref (k)-S OC_min (k)(4)

[0058] In formula (4), Δ _ref (k) is the strategy selection reference value of the battery module at time k; S OC_ref (k) is the charge state reference value at time k; S OC_min (k) is the minimum SOC value of all cells in the battery module at time k.

[0059] Step S5: Selecting a reference value Δ according to the strategy of the battery module _ref (k), determine to adopt the extreme value method balancing strategy or the odd-even method balancing strategy; in step S5, the process of selecting to adopt the extreme value method balancing strategy or the odd-even method balancing strategy is expressed as follows:

[0060]

[0061] In formula (5), β is the strategy selection threshold.

[0062] Step S6: adopting the combined battery balancing control method that couples the extreme value balancing strategy with the odd-even balancing strategy to balance the SOC of the single battery. In step S6, the process of using the extreme value balancing strategy to balance the SOC of the single battery is specifically as follows:

[0063] When the extreme value method balancing strategy is used for balancing, if the single battery B in the battery module _u The SOC value of single battery B is the highest. _v When the SOC value of is the lowest and the parity of the two single battery numbers is different, the working state of the balancing switch unit is:

[0064]

[0065] In formula (6), S d_u is the uth first switch; S c_v is the vth second switch; T1 is the charging cycle of the active balancing unit; T is a balancing cycle; t is the balancing time;

[0066] If the single battery B in the battery module _u The SOC value of single battery B is the highest. _v The SOC value of the battery is the lowest, and the parity of the two battery numbers is the same, the definition is the same as that of the battery B _u Adjacent single cell B _w is a hub battery; then the working state of the balancing switch unit is:

[0067]

[0068] In formula (7), S d_w is the wth first switch; S c_w is the wth second switch.

[0069] Furthermore, in step S6, the process of using the odd-even balancing strategy to balance the SOC of the single cells is specifically as follows:

[0070] When the odd-even balancing strategy is used for balancing, if the single battery B with an odd number in the battery module _v The SOC value of is the lowest, then the working state of the balancing switch unit is:

[0071]

[0072] In formula (8), S d_2、4……2n is the first switch of all even-numbered single cells; T1 is the charging cycle of the active balancing unit; T is a balancing cycle; t is the balancing time;

[0073] When the odd-even balancing strategy is used for balancing, if the single battery B in the battery module is even-numbered _v The SOC value of is the lowest, then the working state of the balancing switch unit is:

[0074]

[0075] In formula (9), S d_1、3……2n-1 The first switch for all odd-numbered cells.

[0076] In this embodiment, SOC is the abbreviation of State of Charge, which is also called the remaining capacity in Chinese. SOC represents the ratio of the remaining capacity of a battery after it has been used for a period of time or has been left unused for a long time to its capacity in a fully charged state, usually expressed as a percentage. The value range of SOC is 0 to 1; when SOC = 0, it means that the battery is fully discharged; when SOC = 1, it means that the battery is fully charged.

[0077] In this embodiment, when the first switch S of the balancing switch unit is d Or the second switch S c When the output value of is 1, it means that the corresponding switch is closed. For example, in formula (7), S d_w =1, (T1≤t<T1+T), then it represents the wth first switch S d_w In closed state.

[0078] In this embodiment, the combined battery balancing control method based on coupled inductors provided by the present invention is applicable to the coupled inductor battery balancing model constructed. Specifically, through the combined balancing control method combining the odd-even strategy with the extreme value method, more single cells are involved in the energy transfer process at the same time, thereby greatly improving the balancing efficiency.

[0079] In one embodiment of the present invention, Figure 2 As shown, the circuit corresponding to the coupled inductor battery balancing model specifically includes: a first balancing switch unit, a second balancing switch unit, ..., a (2n-1)th balancing switch unit, a 2nth balancing switch unit, an active balancing unit and a battery module connected in series; wherein each balancing switch unit is composed of a first switch S connected in series. d and the second switch S c The active balancing unit is composed of a coupled inductor with a 2n winding; the battery module is composed of 2n single cells B connected in series _1 , B _2 ,……,B _2n-1 and B _2n The first switch S of each balancing switch unit is constituted; dThe negative electrode of the second switch S c The negative electrode of the (2m-1)th balancing switch unit is connected to the second switch S c_2m-1 The positive electrode is connected to the single battery B through a wire _2m-1 The positive electrode of the (2m-1)th balancing switch unit is connected to the first switch S d_2m-1 The positive pole of the coupled inductor is connected through a winding L _m With single battery B _2m-1 The negative electrode of the second switch S of the 2mth balancing switch unit is connected; c_2m The positive pole of the coupled inductor is connected through a winding L _m With single battery B _2m The positive electrode of the first switch S of the 2mth balancing switch unit is connected. d_2m The positive electrode is connected to the single battery B through a wire _2m The negative pole of the coupled inductor is connected; wherein n represents the total number of windings of the coupled inductor; m represents the serial number of a winding of the coupled inductor, and m∈[1,n].

[0080] Furthermore, the first switch and the second switch of each balancing switch unit are both composed of a MOSFET tube and an anti-reverse diode connected in parallel at both ends thereof; each balancing switch unit is used to control the energy transfer and exchange between the single battery and the active balancing unit. Furthermore, the cathode of the anti-reverse diode connected in parallel with the first switch is connected to the cathode of the first switch, and the cathode of the anti-reverse diode connected in parallel with the second switch is connected to the cathode of the second switch.

[0081] Finally, MATLAB / Simulink is used to simulate and analyze the model proposed in this invention, and the results are as follows: Figure 3 and Figure 4 shown. Figure 3 A graph showing the SOC and balancing time of each single cell when using the currently commonly used balancing method. Figure 4 The figure shows the SOC and balancing time of each single battery to reach the balancing standard value when the balancing method of the present invention is used. Figure 3 and Figure 4 As shown, the solution adopted by the present invention can increase the energy of low-capacity single cells and reduce the energy consumed by high-capacity single cells, thereby effectively improving energy utilization while improving balancing efficiency.

[0082] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A combined battery balancing control method based on coupled inductors, characterized in that: The control method takes the battery module as the research object and builds a coupled inductor battery balancing model; the battery module is composed of a plurality of single cells, and the plurality of single cells are numbered 1, 2, 3, ..., 2n-1, 2n; n is a positive integer; the control method includes: Step S1: Obtain the real-time SOC of each single battery through the switch control unit; Step S2: Calculate the SOC extreme value Δ of the battery module according to the real-time SOC of each single battery _all (k); Step S3: According to the SOC extreme difference value Δ of the battery module _all (k), determining whether to turn on the circuit corresponding to the coupled inductor battery balancing model; when it is determined that the circuit corresponding to the coupled inductor battery balancing model is turned on, executing step S4; Step S4: Determine the charge state reference value S according to the real-time SOC of each single cell and the parity of the number corresponding to each single cell. OC_ref (k), and then calculate the strategy selection reference value Δ of the battery module in real time _ref (k); Step S5: Selecting a reference value Δ according to the strategy of the battery module _ref (k) Determine whether to adopt the extreme value method equilibrium strategy or the even-odd method equilibrium strategy; Step S6: adopting a combined battery balancing control method that couples the extreme value balancing strategy with the even-odd balancing strategy to perform SOC balancing of single cells.

2. The method for controlling battery balancing based on coupled inductors according to claim 1, characterized in that: The real-time state of charge of each single cell in step S1 is obtained as follows: the SOC of each single cell in the battery module is obtained by the switch control unit at every specified period, and the balancing control strategy is executed; after each single cell executes this round of balancing control strategy, the SOC of each single cell will change; when executing the next cycle, the SOC of each single cell in the battery module is obtained again by the switch control unit, and the balancing strategy is reselected for balancing control.

3. The method for controlling battery balancing based on coupled inductors according to claim 1, characterized in that: The SOC extreme value Δ of the battery module _all The expression of (k) is: Δ _all (k)=S oc_max (k)-S oc_min (k)(1) In formula (1), Δ _all (k) is the equilibrium reference value at time k; S OC_max (k) is the maximum SOC value of each single cell in the battery module at time k; S OC_min (k) is the minimum SOC value of each single cell in the battery module at time k.

4. The method for controlling battery balancing based on coupled inductors according to claim 1, characterized in that: In step S3, the process of determining whether to start the circuit corresponding to the coupled inductor battery balancing model is expressed as follows: In formula (2), α is the equilibrium start threshold.

5. The method for controlling combined battery balancing based on coupled inductors according to claim 1, characterized in that: In step S4, the charge state reference value S is determined. OC_ref The process of (k) is expressed as: In formula (3), x is the battery number corresponding to the single battery with the smallest SOC in the battery module at time k; S OCmin_奇 (k) is the minimum SOC value of all odd-numbered cells in the battery module at time k; S OCmin_偶 (k) is the minimum SOC value of all even-numbered cells in the battery module at time k; In step S4, the strategy selection reference value Δ of the battery module is calculated in real time. _ref The process of (k) is expressed as: Δ _ref (k)=S OC_ref (k)-S OC_min (k)(4) In formula (4), Δ _ref (k) is the strategy selection reference value of the battery module at time k; S OC_ref (k) is the charge state reference value at time k; S OC_min (k) is the minimum SOC value of all cells in the battery module at time k.

6. The method for controlling battery balancing based on coupled inductors according to claim 1, characterized in that: In step S5, the process of selecting the extreme value method balancing strategy or the even-odd method balancing strategy is expressed as follows: In formula (5), β is the strategy selection threshold.

7. The method for controlling battery balancing based on coupled inductors according to claim 1, characterized in that: The circuit corresponding to the coupled inductor battery balancing model specifically includes: a first balancing switch unit, a second balancing switch unit, ..., a (2n-1)th balancing switch unit, a 2nth balancing switch unit, an active balancing unit and a battery module connected in series; wherein each balancing switch unit is composed of a first switch S connected in series. d and the second switch S c The active balancing unit is composed of a coupled inductor with a 2n winding; the battery module is composed of 2n single cells B connected in series _1 , B _2 ,……,B _2n-1 and B _2n constitute; The first switch S of each balancing switch unit d The negative electrode of the second switch S c The negative electrode of the (2m-1)th balancing switch unit is connected to the second switch S c_2m-1 The positive electrode is connected to the single battery B through a wire _2m-1 The positive electrode of the (2m-1)th balancing switch unit is connected to the first switch S d_2m-1 The positive pole of the coupled inductor is connected through a winding L _m With single battery B _2m-1 The negative electrode of the second switch S of the 2mth balancing switch unit is connected; c_2m The positive pole of the coupled inductor is connected through a winding L _m With single battery B _2m The positive electrode of the first switch S of the 2mth balancing switch unit is connected. d_2m The positive electrode is connected to the single battery B through a wire _2m The negative pole is connected; Wherein, n represents the total number of windings of the coupled inductor; m represents the serial number of a winding of the coupled inductor, and m∈[1,n].

8. The method for controlling battery balancing based on coupled inductors according to claim 7, characterized in that: In step S6, the process of using the extreme value method balancing strategy to balance the SOC of the single battery is specifically as follows: When the extreme value method balancing strategy is used for balancing, if the single battery B in the battery module _u The SOC value of single battery B is the highest. _v When the SOC value of is the lowest and the parity of the two single battery numbers is different, the working state of the balancing switch unit is: In formula (6), S d_u is the uth first switch; S c_v is the vth second switch; T1 is the charging cycle of the active balancing unit; T is a balancing cycle; t is the balancing time; If the single battery B in the battery module _u The SOC value of single battery B is the highest. _v The SOC value of the battery is the lowest, and the parity of the two battery numbers is the same, the definition is the same as that of the battery B _u Adjacent single cell B _w is a hub battery; then the working state of the balancing switch unit is: In formula (7), S d_w is the wth first switch; S c_w is the wth second switch.

9. The method for controlling battery balancing based on coupled inductors according to claim 7, characterized in that: In step S6, the process of using the even-odd method to balance the SOC of the single cells is specifically as follows: When the odd-even balancing strategy is used for balancing, if the single battery B with an odd number in the battery module _v The SOC value of is the lowest, then the working state of the balancing switch unit is: In formula (8), S d_2、4……2n is the first switch of all even-numbered single cells; T1 is the charging cycle of the active balancing unit; T is a balancing cycle; t is the balancing time; When the odd-even balancing strategy is used for balancing, if the single battery B in the battery module is even-numbered _v The SOC value of is the lowest, then the working state of the balancing switch unit is: In formula (9), S d_1、3……2n-1 The first switch for all odd-numbered cells.

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