System, integrated circuit and method for equalizing battery pack and stacking battery pack

Abstract

Systems, integrated circuits, and methods for equalizing and stacking battery packs are disclosed. The battery pack comprises n batteries connected in series, and n is an integer larger than or equal to 3. The system comprises an energy transfer unit which comprises an inductor and a first switch tube pair coupled between the positive electrode of an nth battery and the negative electrode of a first battery, the middle node of the first switch tube pair is coupled to the first end of the inductor, and the second end of the inductor is coupled to the positive electrode of a first target battery or the negative electrode of a second target battery in a time-sharing mode, the first target battery is the battery with the highest voltage from the first battery to the n-1 battery, and the second target battery is the battery with the highest voltage from the second battery to the n battery; and the first gate driver and the second gate driver are used for driving the first switching tube pair to operate in a switching manner. The energy transfer unit works in a boost mode when the second end of the inductor is coupled to the positive electrode of the first target battery, and works in a buck mode when the second end of the inductor is coupled to the negative electrode of the second target battery.

Description

Technical Field

[0001] The present invention relates to a switching power supply, and in particular, to a system, an integrated circuit, and a method for equalizing battery packs and stacked battery packs. Background Art

[0002] A battery pack usually includes several single cells connected in series. Due to the differences in the charging state, impedance, and temperature characteristics of each single cell, there will be an imbalance between the battery cells. This imbalance phenomenon will reduce the capacity of the entire battery pack and shorten its lifespan. Therefore, a battery equalization circuit needs to be used in the battery pack to adjust it in order to maintain the capacity of the battery pack and extend its lifespan.

[0003] Common battery equalization circuits in the prior art include a passive resistor equalization circuit and an active equalization circuit including a capacitor, an inductor, or a transformer. The passive resistor equalization circuit consumes excess energy through a resistor, with low efficiency and a large amount of heat generation. And the common active equalization circuit including a capacitor, an inductor, or a transformer cannot be accepted by customers due to defects such as complex circuits and lack of stability.

[0004] Figure 1 For the passive resistor equalization circuit 10 in the prior art. As Figure 1 shown, the passive resistor equalization circuit 10 includes a bypass resistor and a bypass field effect transistor (FET) connected in parallel with the battery. In the passive resistor equalization circuit 10, the battery cell with a higher voltage is discharged through the bypass resistor and the bypass FET, so that the voltages between the battery cells of the battery pack can be equalized. Although this technical solution is relatively simple, it can only adjust the battery cell with a higher voltage, and the excess energy can only be dissipated in the form of heat, with low equalization efficiency.

[0005] Figure 2 For the active equalization circuit 20 including a capacitor in the prior art. As Figure 2 shown, in the active equalization circuit 20, the capacitor continuously switches between two adjacent battery cells to equalize the capacities between the battery cells of the battery pack. Although this technical solution has higher efficiency than the passive resistor equalization, a large amount of energy is still dissipated during the capacitor charging process, and the energy can only be transferred between adjacent battery cells.

[0006] Figure 3 For the active equalization circuit 30 including a transformer in the prior art. As Figure 3 shown, in the equalization circuit 30, energy can be transferred between the battery pack and each battery cell in the battery pack. This technical solution has a relatively fast equalization speed, but the use of a transformer increases the circuit cost and circuit size.

[0007] Figure 4 The active balancing circuit 40 including an inductor in the prior art is shown in FIG. Figure 4 As shown, the balancing circuit 40 performs energy transfer in a buck-boost converter mode. In this technical solution, energy can only be transferred between two adjacent battery cells, the balancing speed is slow, and the balancing efficiency is not high. Summary of the invention

[0008] The present invention provides a system, an integrated circuit and a method for balancing battery packs and stacking battery packs, which can achieve good balancing effects while saving system cost and volume.

[0009] According to the present invention, a system for balancing a battery pack is proposed, the battery pack includes battery No. 1, battery No. 2, ..., battery No. n connected in series in sequence, wherein n is an integer greater than or equal to 3, the system includes: an energy transfer unit, including a first switch tube pair and a first inductor, wherein the first switch tube pair is coupled between the positive electrode of battery No. n and the negative electrode of battery No. 1, the middle node of the first switch tube pair is coupled to the first end of the first inductor, and the second end of the first inductor is coupled to the positive electrode of the first target battery or the negative electrode of the second target battery in a time-sharing manner, wherein the first target battery is the single cell with the highest or lowest voltage among batteries No. 1 to n-1, and the second target battery is the single cell with the highest or lowest voltage among batteries No. 2 to n. ; and a first gate driver and a second gate driver, in response to the PWM signal, generate a first drive signal and a second drive signal to drive the first switch tube pair to switch operation, wherein when the second end of the first inductor is coupled to the positive electrode of the first target battery, in response to the voltage of the first target battery being the highest, the energy transfer unit is configured to operate in a boost mode, in response to the voltage of the first target battery being the lowest, the energy transfer unit is configured to operate in a buck mode, and when the second end of the first inductor is coupled to the negative electrode of the second target battery, in response to the voltage of the second target battery being the highest, the energy transfer unit is configured to operate in a buck mode, and in response to the voltage of the second target battery being the lowest, the energy transfer unit is configured to operate in a boost mode.

[0010] According to the present invention, a system for balancing a stacked battery pack is also proposed. The stacked battery pack includes Battery No. 1, Battery No. 2, ······, Battery No. 2n - 1 connected in series in sequence. Among them, Battery No. 1 to Battery No. n form the first sub - battery pack, and Battery No. n to Battery No. 2n - 1 form the second sub - battery pack, where n is an integer greater than or equal to 3. The system includes: a first energy transfer unit, including a first pair of switching tubes and a first inductor. The first pair of switching tubes is coupled between the positive electrode of Battery No. n and the negative electrode of Battery No. 1. The middle node of the first pair of switching tubes is coupled to the first end of the first inductor. The second end of the first inductor is coupled to the positive electrode of the first target battery or the negative electrode of the second target battery at different times. The first target battery is the single - cell battery with the highest or lowest voltage among Battery No. 1 to Battery No. n - 1, and the second target battery is the single - cell battery with the highest or lowest voltage among Battery No. 2 to Battery No. n; a second energy transfer unit, including a second pair of switching tubes and a second inductor. The second pair of switching tubes is coupled between the positive electrode of Battery No. 2n - 1 and the negative electrode of Battery No. n. The middle node of the second pair of switching tubes is coupled to the first end of the second inductor. The second end of the second inductor is coupled to the positive electrode of the third target battery or the negative electrode of the fourth target battery at different times. The third target battery is the single - cell battery with the highest or lowest voltage among Battery No. n to Battery No. 2n - 2, and the fourth target battery is the single - cell battery with the highest or lowest voltage among Battery No. n + 1 to Battery No. 2n - 1; a first gate driver and a second gate driver, which respectively generate first and second driving signals to drive the first pair of switching tubes to switch operation. When the second end of the first inductor is coupled to the positive electrode of the first target battery, in response to the highest voltage of the first target battery, the first energy transfer unit operates in a boost mode, and in response to the lowest voltage of the first target battery, the first energy transfer unit operates in a buck mode. When the second end of the first inductor is coupled to the negative electrode of the second target battery, in response to the highest voltage of the second target battery, the first energy transfer unit operates in a buck mode, and in response to the lowest voltage of the second target battery, the first energy transfer unit operates in a boost mode; and a third gate driver and a fourth gate driver, which respectively generate third and fourth driving signals to drive the second pair of switching tubes to switch operation. When the second end of the second inductor is coupled to the positive electrode of the third target battery, in response to the highest voltage of the third target battery, the second energy transfer unit operates in a boost mode, and in response to the lowest voltage of the third target battery, the second energy transfer unit operates in a buck mode. When the second end of the second inductor is coupled to the negative electrode of the fourth target battery, in response to the highest voltage of the fourth target battery, the second energy transfer unit operates in a buck mode, and in response to the lowest voltage of the fourth target battery, the second energy transfer unit operates in a boost mode.

[0011] According to the present invention, a method for balancing a battery pack is provided. The battery pack includes a No. 1 battery, a No. 2 battery, ······, a No. n battery connected in series in sequence, where n is an integer greater than or equal to 3. The method includes: determining the single battery with the highest voltage among the No. 1 to No. n batteries; using a first pair of switching tubes coupled between the positive electrode of the No. n battery and the negative electrode of the No. 1 battery, and coupling the intermediate node of the first pair of switching tubes to the first end of a first inductor, wherein the first pair of switching tubes and the first inductor form an energy conversion unit; if the voltage of the No. 1 battery is the highest, coupling the second end of the first inductor only to the positive electrode of the No. 1 battery, and configuring the energy conversion unit to operate in a boost mode; if the voltage of the No. n battery is the highest, coupling the second end of the first inductor only to the negative electrode of the No. n battery, and configuring the energy conversion unit to operate in a buck mode; and if the voltage of the single target battery among the No. 2 to No. n-1 batteries is the highest, coupling the second end of the first inductor only to the negative electrode of the target battery, configuring the energy conversion unit to operate in a buck mode within a first time period, and after the first time period, coupling the second end of the first inductor only to the positive electrode of the target battery, and configuring the energy conversion unit to operate in a boost mode within a second time period.

[0012] According to the present invention, another method for balancing a battery pack is provided. The battery pack includes a No. 1 battery, a No. 2 battery, ······, a No. n battery connected in series in sequence, where n is an integer greater than or equal to 3. The method includes: determining the single battery with the lowest voltage among the No. 1 to No. n batteries; using a first pair of switching tubes coupled between the positive electrode of the No. n battery and the negative electrode of the No. 1 battery, and coupling the intermediate node of the first pair of switching tubes to the first end of a first inductor, wherein the first pair of switching tubes and the first inductor form an energy conversion unit; if the voltage of the No. 1 battery is the lowest, coupling the second end of the first inductor only to the positive electrode of the No. 1 battery, and configuring the energy conversion unit to operate in a buck mode; if the voltage of the No. n battery is the lowest, coupling the second end of the first inductor only to the negative electrode of the No. n battery, and configuring the energy conversion unit to operate in a boost mode; and if the voltage of the single target battery among the No. 2 to No. n-1 batteries is the lowest, coupling the second end of the first inductor only to the negative electrode of the target battery, configuring the energy conversion unit to operate in a boost mode within a first time period, and after the first time period, coupling the second end of the first inductor only to the positive electrode of the target battery, and configuring the energy conversion unit to operate in a buck mode within a second time period.

[0013] According to the present invention, a method for equalizing a battery pack is also provided. The battery pack includes a No. 1 battery, a No. 2 battery, ······, a No. 2n-1 battery connected in series in sequence, wherein the No. 1 to No. n batteries form a first sub-battery pack, and the No. n to No. 2n-1 batteries form a second sub-battery pack, and n is an integer greater than or equal to 3. The method includes: using a first switch pair coupled between the positive electrode of the No. n battery and the negative electrode of the No. 1 battery, and coupling the intermediate node of the first switch pair to the first end of a first inductor, wherein the first switch pair and the first inductor form a first energy conversion unit; using a second switch pair coupled between the positive electrode of the No. 2n-1 battery and the negative electrode of the No. n battery, and coupling the intermediate node of the second switch pair to the first end of a second inductor, wherein the second switch pair and the second inductor form a second energy conversion unit; and in response to the inter-group equalization requirement between the first sub-battery pack and the second sub-battery pack, coupling the second end of the first inductor to the negative electrode of the No. n battery, and coupling the second end of the second inductor to the positive electrode of the No. n battery.

[0014] According to the present invention, an integrated circuit for equalizing a battery pack is further provided. The battery pack includes a No. 1 battery, a No. 2 battery, ······, a No. n battery connected in series in sequence, wherein n is an integer greater than or equal to 3. The integrated circuit includes: a first battery pin coupled to the negative electrode of the No. 1 battery; a second battery pin to an (n + 1)-th battery pin, respectively and sequentially coupled to the positive electrodes of the No. 1 to No. n batteries; a first power pin coupled to a second power pin via an inductor; the second power pin is coupled to the positive electrode of a first target battery or the negative electrode of a second target battery in a time-sharing manner, wherein the first target battery is the single battery with the highest or lowest voltage among the No. 1 to No. n-1 batteries, and the second target battery is the single battery with the highest or lowest voltage among the No. 2 to No. n batteries; a first switch pair coupled between the (n + 1)-th battery pin and the first battery pin, wherein the intermediate node of the first switch pair is coupled to the first power pin, and the first switch pair and the inductor form an energy conversion unit; and wherein when the second power pin is coupled to the positive electrode of the first target battery, in response to the highest voltage of the first target battery, the energy transfer unit operates in a boost mode, and in response to the lowest voltage of the first target battery, the energy transfer unit operates in a buck mode, and when the second power pin is coupled to the negative electrode of the second target battery, in response to the highest voltage of the second target battery, the energy transfer unit operates in a buck mode, and in response to the lowest voltage of the second target battery, the energy transfer unit operates in a boost mode.

[0015] According to an embodiment of the present invention, the equalization of an n-series battery pack only requires one inductor, one switch pair and n - 1 conduction paths, which saves costs while meeting the equalization requirements of the battery pack. Further, according to an embodiment of the present invention, the voltage equalization between battery packs can also be quickly achieved in response to the equalization requirements between battery packs to meet user needs. Description of the Drawings

[0016] Figure 1 is the passive resistor equalization circuit 10 in the prior art;

[0017] Figure 2 is the active equalization circuit 20 including a capacitor in the prior art;

[0018] Figure 3 is the active equalization circuit 30 including a transformer in the prior art;

[0019] Figure 4 is the active equalization circuit 40 including an inductor in the prior art;

[0020] Figure 5 is the principle block diagram of the system 100 for equalizing a battery pack according to an embodiment of the present invention;

[0021] Figure 6 is the circuit diagram of the system 100A for equalizing a battery pack according to another embodiment of the present invention;

[0022] Figure 7A is the energy transfer unit 105A operating in the buck mode according to an embodiment of the present invention;

[0023] Figure 7B is the energy transfer unit 105A operating in the boost mode according to an embodiment of the present invention;

[0024] Figure 8 is the schematic diagram of the system 100B for equalizing a battery pack according to an embodiment of the present invention;

[0025] Figure 9 is the schematic diagram of the system 200 for equalizing a stacked battery pack according to an embodiment of the present invention;

[0026] Figure 10 is the circuit diagram of the system 200A for equalizing a stacked battery pack according to another embodiment of the present invention;

[0027] Figure 11 is the flowchart of the method 500 for equalizing a battery pack according to an embodiment of the present invention;

[0028] Figure 12 is the flowchart of the method 600 for equalizing a stacked battery pack according to an embodiment of the present invention;

[0029] Figure 13 is the schematic diagram of the integrated circuit IC1 for equalizing a battery pack according to an embodiment of the present invention. Detailed implementation manners

[0030] Specific embodiments of the present invention will be described in detail below. It should be noted that the embodiments described herein are for illustrative purposes only and are not intended to limit the present invention. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to one of ordinary skill in the art that the present invention need not be practiced with these specific details. In other instances, well-known circuits, materials, or methods have not been specifically described to avoid obscuring the present invention.

[0031] Throughout the specification, references to "one embodiment", "an embodiment", "one example", or "an example" mean that a particular feature, structure, or characteristic described in connection with the embodiment or example is included in at least one embodiment of the present invention. Thus, the phrases "in one embodiment", "in an embodiment", "one example", or "an example" appearing throughout the specification are not necessarily all referring to the same embodiment or example. Furthermore, the particular features, structures, or characteristics may be combined in any suitable combination and / or sub-combination in one or more embodiments or examples. In addition, those of ordinary skill in the art will understand that the drawings provided herein are for illustrative purposes only and are not necessarily drawn to scale. It should be understood that when an element is referred to as being "connected to" or "coupled to" another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being "directly connected to" or "directly coupled to" another element, no intervening elements are present. Like reference numerals indicate like elements. The term "and / or" used herein includes any and all combinations of one or more of the associated listed items.

[0032] Figure 5 is a schematic block diagram of a system 100 for balancing a battery pack according to an embodiment of the present invention. As Figure 5 shown, the system 100 includes a battery pack 101 and a battery management system 102. The battery pack 101 has a plurality of single cells connected in series in sequence between battery pack terminals V+ and V-. The battery pack 101 includes a first cell C1, a second cell C2, ······, an nth cell Cn connected in sequence, where n is an integer greater than or equal to 3. In Figure 5 the illustrated embodiment, the battery pack 101 includes five single cells C1 to C5 connected in series in sequence.

[0033] As Figure 5As shown, the battery management system 102 includes a sampling unit 103, a control unit 104, an energy transfer unit 105, a plurality of conduction paths 106, a first gate driver 107, and a second gate driver 108. The sampling unit 103 is connected to each single cell in the battery pack 101, respectively, for collecting the voltage of each single cell. The control unit 104 is connected to the sampling unit 103, for receiving and monitoring the voltage of each series-connected single cell, determining its state in the entire battery pack 101, and determining the target battery with the highest or lowest battery voltage, and then determining whether the start condition of battery pack balancing is met.

[0034] In one embodiment, the control unit 104 starts the battery pack balancing by: obtaining the total average voltage of the entire battery pack 101, and calculating the difference between the single cell with the highest battery voltage and the total average voltage. When the voltage of the target battery exceeds the total average voltage of the battery pack 101 minus a preset balancing threshold, it is determined that the balancing demand of the single cell has arrived, and the control unit 104 outputs the selection control signal MUX, selects one of the multiple conduction paths 106, and outputs the PWM signal to the first gate driver 107 and the second gate driver 108. In one embodiment, the control unit 104 ends the battery pack balancing by: after the balancing is completed, re-obtain the total average voltage of the entire battery pack 101, and calculate the difference between the target battery with the highest battery voltage and the total average voltage. When the difference is less than the preset balancing threshold, the balancing end condition is met. The control unit 104 no longer outputs the selection control signal MUX and the PWM signal.

[0035] exist Figure 5 In the illustrated embodiment, the energy transfer unit 105 includes a first switch pair and an inductor L1, wherein the first switch pair includes a high-side switch QH and a low-side switch QL. The first switch pair is coupled between the positive electrode of the nth battery (i.e., the battery pack terminal V+) and the negative electrode of the 1st battery (i.e., the battery pack terminal V-). The middle node of the first switch pair is coupled to the first end of the inductor L1. The second end of the inductor L1 is coupled to the positive electrode of the first target battery or the negative electrode of the second target battery in a time-sharing manner, wherein the first target battery is the single cell with the highest voltage among the batteries 1 to n-1, and the second target battery is the single cell with the highest voltage among the batteries 2 to n. When the voltage of the target battery exceeds a certain amplitude of the total average voltage, the control unit 104 selects one of the multiple conduction paths 106 to conduct, thereby realizing the electrical connection between the second end of the inductor L1 and the single cell target battery with the highest battery voltage. In one embodiment, the second end of the inductor L1 is coupled to the positive electrode of the first target battery during a first time period t1 , and is coupled to the negative electrode of the second target battery during a second time period t2 .

[0036] In response to the PWM signal, the first gate driver 107 and the second gate driver 108 process the PWM signal generated by the control unit 104 and convert it into complementary non-overlapping first driving signal GH and second driving signal GL, which are used to directly drive the high-side switch tube QH and the low-side switch tube QL of the first switch tube pair to perform switching operation. This is because the output capacity of the control unit 104 is limited and cannot directly drive the high-side switch tube QH and the low-side switch tube QL in the energy transfer unit 105. The first gate driver 107 and the second gate driver 108 are required to enhance the driving ability to control the conduction and cutoff of the first switch tube pair.

[0037] When the second end of the inductor L1 is coupled to the positive electrode of the first target battery, the energy transfer unit 105 is configured to operate in a boost mode. When the second end of the inductor L1 is coupled to the negative electrode of the second target battery, the energy transfer unit 105 is configured to operate in a buck mode. Through such an equalization method, the target battery with the highest battery voltage in the battery pack 101 transfers energy to other batteries in the battery pack 101, so that the battery voltage of the target battery converges to the target average voltage.

[0038] In one embodiment, the first target battery is battery No. 1, that is, the voltage of battery No. 1 is the highest. The second end of the inductor L1 is electrically connected to the positive electrode of the first target battery, that is, the positive electrode of battery No. 1. At this time, the energy transfer unit 105 is configured to operate in a boost mode.

[0039] In another embodiment, the second target battery is battery No. n, that is, the voltage of battery No. n is the highest. The second end of the inductor L1 is electrically connected to the negative electrode of the second target battery, that is, the negative electrode of battery No. n. At this time, the energy transfer unit 105 is configured to operate in a buck mode.

[0040] In yet another embodiment, the first target battery and the second target battery are the same single battery among batteries No. 2 to n - 1. The positive and negative electrodes of this single battery are coupled to the second end of the inductor L1 at different times. Specifically, taking the case where the voltage of battery No. 3 is the highest as an example, first connect the second end of the inductor L1 to the negative electrode of battery No. 3, and the energy transfer unit 105 is configured to operate in a buck mode. After the buck mode lasts for the first duration t1, reconnect the second end of the inductor L1 to the positive electrode of battery No. 3, and the energy transfer unit 105 is configured to operate in a boost mode, and the boost mode lasts for the second duration t2.

[0041] Figure 6 It is a circuit diagram of a system 100A for equalizing a battery pack according to an embodiment of the present invention. As Figure 6As shown, the plurality of conduction paths 106A include four switches S1-S4, which are gated and controlled by a gate control signal MUX. The energy transfer unit 105A includes a first switch pair consisting of two MOSFET transistors and an inductor L1.

[0042] Specifically, according to an embodiment of the present invention, for a battery pack 101 having n series-connected single cells, the plurality of conduction paths 106A include n-1 switches S1 to S(n-1). Figure 6 In the illustrated embodiment, the battery pack 101 includes five single cells C1-C5 connected in series. Accordingly, the plurality of conduction paths 106A include four switches S1-S4 to couple the second end of the inductor L1 to the positive or negative electrode of the target battery in a time-sharing manner. In one embodiment, the gating control signal MUX can switch the switches S1-S4 between a fully on state and a fully off state.

[0043] The following uses the No. 3 battery as the single target battery with the highest battery voltage as an example. Figure 7A and 7B The working principle of the energy transfer unit 105A will be described in detail.

[0044] Figure 7A The energy transfer unit 105A operates in the buck mode according to an embodiment of the present invention. When the battery voltage of the No. 3 battery C3 is the highest and exceeds a preset threshold value of the total average voltage, the second end of the inductor L1 is coupled to the negative electrode of the No. 3 battery C3, and the energy transfer unit 105A enters the buck mode. Figure 7A As shown. The high-side switch tube QH is turned on first, and the high-side switch tube QH, inductor L1, and battery No. 3 C3 to battery No. 5 C5 form a discharge circuit, that is, C3~C5 are all in a discharge state, discharging to the inductor L1, and the inductor L1 converts the released electrical energy into energy storage. Subsequently, the high-side switch tube QH is turned off, the low-side switch tube QL is turned on, and the inductor L1 and battery No. 1 C1 and battery No. 2 C2 form a charging circuit. The inductor L1 charges C1 and C2, and the energy stored in the inductor L1 is transferred to C1 and C2. After that, the high-side switch tube QH is turned on again, the low-side switch tube QL is turned off, and C3~C5 are discharged again, and then this process is repeated. In this process, the high-side switch tube QL and the low-side switch tube QL are turned on alternately, and the entire buck mode lasts for the first duration t1.

[0045] Figure 7B is an energy transfer unit 105A operating in a boost mode according to an embodiment of the present invention. After the first time duration t1, as Figure 7BAs shown, the second terminal of inductor L1 is disconnected from the negative electrode of battery C3, and is re - electrically coupled to the positive electrode of battery C3. The energy transfer unit 105A enters the boost mode of operation. The low - side switch QL is turned on first. The low - side switch QL, inductor L1, and batteries C1 to C3 form a discharge circuit. At this time, C1 - C3 are in the discharge state and discharge to inductor L1, and inductor L1 converts the released electrical energy into energy storage. Subsequently, the low - side switch QL is turned off, and the high - side switch QH is turned on. The high - side switch QH, inductor L1, and batteries C4 and C5 form a charging circuit. Therefore, in the boost mode, C4 and C5 are in the charging state. After that, the low - side switch QL is turned on again, and the high - side switch QH is turned off, and the above process is repeated continuously. During this process, the high - side switch QL and the low - side switch QL are alternately turned on, and the entire boost mode lasts for the first duration t2.

[0046] Assume that all batteries have approximately the same impedance, and the current flowing through inductor L1 is I. Approximately 2 / 5I of the current flows out of the batteries in the discharge state, and 3 / 5I of the current flows into the batteries in the charging state. Specifically, in the buck mode, the batteries in the charging state are battery C1 and battery C2, and in the boost mode, the batteries in the charging state are battery C4 and battery C5. It can be seen that battery C3, as the target battery, is always in the discharge state. In one embodiment, if the average voltage of the batteries in the charging state in the buck mode is less than the average voltage of the batteries in the charging state in the boost mode, the control unit 104 will increase the ratio of the first duration t1 to the second duration t2.

[0047] According to an embodiment of the present invention, the energy transfer unit 105A performs active balancing, which can achieve large - current and fast balancing within the battery pack. Compared with the passive balancing method, the time required for active balancing will be greatly shortened, and the balancing efficiency can be improved. By adopting this balancing method, it is more capable of extending the discharge duration of the battery pack 101 to the load, improving the discharge performance, extending the service life of the battery pack 101, and ultimately achieving the effect of energy conservation and emission reduction.

[0048] Figure 8 It is a schematic diagram of a system 100B for balancing a battery pack according to an embodiment of the present invention. As Figure 8As shown, system 100B includes a battery pack 101, an energy transfer unit 105A, and an integrated circuit IC. The integrated circuit IC is used to cooperate with the energy transfer unit 105A to equalize the voltages of the individual cells connected in series within the battery pack 101. The integrated circuit IC includes a plurality of conduction paths 106B, a first gate driver 107, a second gate driver 108, and a plurality of pins. The plurality of pins include a ground pin GND coupled to the negative electrode of cell C1, pins C2 to C4 respectively coupled to the negative electrodes of cells C2 to C5, a pin V+ coupled to the positive electrode of cell C5, a drive pin DRV1 coupled to the gate of the high-side switch transistor QH, a drive pin DRV2 coupled to the gate of the low-side switch transistor QL, and a pin L coupled to the second end of the inductor L1.

[0049] As Figure 8 shown, the plurality of conduction paths 106B include four-way switches S1 to S4 to respectively provide an electrical connection between the second end of the first inductor L1 and the positive electrode of the first target cell. In one embodiment, each of the switches S1 to S4 respectively includes two N-channel MOSFETs connected in anti-phase series. In Figure 8 the embodiment shown, the switch S4 that can be coupled to the negative electrode of cell C5 and the switch S1 that can be coupled to the positive electrode of cell C1 include a one-way switch, and S3 and S2 respectively include two two-way switches connected in anti-phase series.

[0050] It can be seen that the integrated circuit IC topology adopted by the present invention is simple and has low cost. Equalizing n series-connected cells only requires one inductor, one pair of switch transistors, and n - 1 conduction paths.

[0051] Figure 9 Schematic diagram of a system 200 for equalizing a stacked battery pack according to an embodiment of the present invention. As Figure 9 shown, the system 200 includes a battery pack 101A, a sampling unit 103A, a control unit 104A, a first energy transfer unit 1051, a second energy transfer unit 1052, a plurality of first conduction paths 1061, a plurality of second conduction paths 1062, and first to fourth gate drivers 107 to 110. The battery pack 101A has 2n - 1 individual cells connected in series in sequence between the battery pack terminals V+ and V-. The battery pack 101A includes cells C1, C2,..., C(2n - 1) connected in sequence, where n is an integer greater than or equal to 3. In Figure 9In the embodiment shown, the battery pack 101A includes 9 single cells C1-C9 connected in series. Cells 1 to 5 form a first sub-battery group (i.e., C1-C5), and cells 5 to 9 form a second sub-battery group (i.e., C5-C9). The plurality of first conductive paths 1061 include four switches S1-S4, and the plurality of second conductive paths 1062 include four switches S5-S6.

[0052] The sampling unit 103A is connected to each single cell in the battery pack 101A, and is used to collect the voltage of each single cell. The control unit 104A is connected to the sampling unit 103A, and is used to receive and monitor the voltage of each series-connected single cell, determine its state in each sub-battery group, determine the target battery with the highest or lowest battery voltage in each sub-battery group, and then determine whether the start condition of the single cell balancing in the battery pack is met.

[0053] In one embodiment, when the need for balancing between two sub-battery groups arises, the control unit 104A outputs a selection control signal MUX1 to turn on the switch S4, and outputs a PWM1 signal to the first gate driver 107 and the second gate driver 108, and simultaneously outputs a selection control signal MUX2 to turn on the switch S5, and outputs a PWM2 signal to the third gate driver 109 and the fourth gate driver 110.

[0054] The first energy transfer unit 1051 includes a first switch tube pair and a first inductor L1, wherein the first switch tube pair is coupled between the positive electrode of the nth battery and the negative electrode of the 1st battery, and includes a high-side switch tube QH and a low-side switch tube QL. The middle node of the first switch tube pair is coupled to the first end of the first inductor L1. The second end of the first inductor L1 is coupled to the positive electrode of the first target battery or the negative electrode of the second target battery in a time-sharing manner, wherein the first target battery is the single cell with the highest voltage among the 1st to n-1st batteries, and the second target battery is the single cell with the highest voltage among the 2nd to nth batteries.

[0055] In response to the PWM1 signal, the first gate driver 107 and the second gate driver 108 respectively generate a first drive signal GH and a second drive signal GL to drive the first switch tube pair. When the second end of the first inductor L1 is coupled to the positive electrode of the first target battery, the first energy transfer unit 1051 is controlled to work in a boost mode, and when the second end of the first inductor L1 is coupled to the negative electrode of the second target battery, the first energy transfer unit 1051 is controlled to work in a buck mode.

[0056] In one embodiment, the first target battery and the second target battery are the same single battery among the batteries numbered from 2 to n - 1, and the positive and negative electrodes of the single battery are coupled to the second end of the first inductor L1 at different times. For example, the voltage of the 3rd battery C3 is the highest, the second end of the first inductor L1 is coupled to the negative electrode of the 3rd battery C3, and the first energy transfer unit 1051 operates in the buck mode within the first time period t1. Subsequently, the second end of the first inductor L1 is coupled to the positive electrode of the 3rd battery C3, and the first energy transfer unit 1051 operates in the boost mode within the second time period t2. When the average voltage of the batteries (C1 and C2) in the first sub-battery pack (C1~C5) in the charging state in the buck mode is less than the average voltage of the batteries (C4 and C5) in the charging state in the boost mode, the ratio of the first time period t1 to the second time period t2 is increased.

[0057] The second energy transfer unit 1052 includes a second switch pair and a second inductor L2. The second switch pair is coupled between the positive electrode of the (2n - 1)th battery and the negative electrode of the nth battery, and includes a high-side switch QH1 and a low-side switch QL. The middle node of the second switch pair is coupled to the first end of the second inductor L2, and the second end of the second inductor L2 is coupled to the positive electrode of the third target battery or the negative electrode of the fourth target battery at different times. The third target battery is the single battery with the highest voltage among the batteries numbered from n to 2n - 2, and the fourth target battery is the single battery with the highest voltage among the batteries numbered from n + 1 to 2n - 1.

[0058] In response to the PWM2 signal, the third gate driver 109 and the fourth gate driver 110 respectively generate a third driving signal GH1 and a fourth driving signal GL1 to drive the second switch pair. When the second end of the second inductor L2 is coupled to the positive electrode of the third target battery, the second energy transfer unit 1052 operates in the boost mode. When the second end of the second inductor L2 is coupled to the negative electrode of the fourth target battery, the second energy transfer unit 1052 operates in the buck mode.

[0059] In one embodiment, the third target battery and the fourth target battery are the same single battery in the battery of number n+1 to number 2n-2, and the positive electrode and the negative electrode of the single battery are coupled to the second end of the second inductor L2 in a time-sharing manner. For example, the voltage of the No. 7 battery C7 is the highest, the second end of the second inductor L2 is coupled to the negative electrode of the No. 7 battery C7, and the second energy transfer unit 1052 operates in the buck mode in the third time length t3. Subsequently, the second end of the second inductor L2 is coupled to the positive electrode of the No. 7 battery C7, and the second energy transfer unit 1052 operates in the boost mode in the fourth time length t4. When the average voltage of the batteries (C5 and C6) in the second sub-battery group (C5-C9) in the buck mode is less than the average voltage of the batteries (C8 and C9) in the boost mode, the ratio of the third time length t3 to the fourth time length t4 is increased.

[0060] Furthermore, the control unit 104A also monitors the voltage difference between the first sub-battery group and the second sub-battery group according to user needs, and when the voltage difference between the two sub-battery groups exceeds a second balancing threshold, determines that there is a need for balancing between the two sub-battery groups, and then starts a balancing mechanism between the two sub-battery groups.

[0061] Figure 10 FIG. 2 is a circuit diagram of a system 200A for balancing stacked battery packs according to another embodiment of the present invention. Figure 10 As shown, in response to the balancing requirement between the first sub-battery group and the second sub-battery group, the gating control signal MUX1 provided by the control unit 104A controls the switch S4 in the plurality of first conduction paths 1061 to be turned on, and the second end of the first inductor L1 is only coupled to the negative electrode of the n-th battery. At the same time, the gating control signal MUX2 provided by the control unit 104A controls the switch S5 in the plurality of second conduction paths 1062 to be turned on, and the second end of the second inductor L2 is only coupled to the positive electrode of the n-th battery.

[0062] If the voltage of the first sub-battery group exceeds the voltage of the second sub-battery group by a second balancing threshold, in response to the PWM1 signal, the first energy transfer unit 1051 operates in a boost mode under the drive of the first gate driver 107 and the second gate driver 108. In response to the PWM2 signal, the second energy transfer unit 1052 also operates in a boost mode under the drive of the third gate driver 109 and the fourth gate driver 110.

[0063] If the voltage of the second sub-battery group exceeds the voltage of the first sub-battery group minus the second balancing threshold, in response to the PWM1 signal, the first energy transfer unit 1051 operates in the buck mode under the drive of the first gate driver 107 and the second gate driver 108. In response to the PWM2 signal, the second energy transfer unit 1052 also operates in the buck mode under the drive of the third gate driver 109 and the fourth gate driver 110.

[0064] Figure 11 It is a flowchart of a method 500 for equalizing a battery pack according to an embodiment of the present invention. The battery pack includes battery No. 1, battery No. 2, ······, battery No. n connected in series in sequence, where n is an integer greater than or equal to 3. The method 500 includes steps 501 to 506.

[0065] In step 501, a first equalization threshold is determined to meet the user's equalization requirement for the series-connected batteries in the battery pack.

[0066] In step 502, the voltage of each single battery is obtained to determine the single battery with the highest voltage among battery No. 1 to battery No. n.

[0067] In step 503, a first switch pair coupled between the positive electrode of battery No. n and the negative electrode of battery No. 1 is used to couple the middle node of the first switch pair to the first end of a first inductor, where the first switch pair and the first inductor form an energy conversion unit.

[0068] In step 504, if the voltage of battery No. 1 is the highest, step 541 is performed to couple the second end of the first inductor only to the positive electrode of battery No. 1, and the energy conversion unit is configured to operate in a boost mode (step 542).

[0069] In step 505, if the voltage of battery No. n is the highest, step 551 is performed to couple the second end of the first inductor only to the negative electrode of battery No. n, and the energy conversion unit is configured to operate in a buck mode (step 552).

[0070] In step 506, if the voltage of the single target battery among battery No. 2 to battery No. n - 1 is the highest, step 561 is performed to couple the second end of the first inductor only to the negative electrode of the target battery, and the energy conversion unit is configured to operate in a buck mode within a first time period (step 562). After the first time period, step 563 is entered to couple the second end of the first inductor only to the positive electrode of the target battery, and the energy conversion unit is configured to operate in a boost mode within a second time period (step 564).

[0071] In one embodiment, when the average voltage of the batteries in the charging state in the buck mode is less than the average voltage of the batteries in the charging state in the boost mode, the ratio of the first time period to the second time period is increased.

[0072] Figure 12Flow chart of method 600 for equalizing a stacked battery pack according to an embodiment of the present invention. The battery pack includes battery No. 1, battery No. 2, ······, battery No. 2n-1 connected in series in sequence, where battery No. 1 to battery No. n form the first sub-battery pack, and battery No. n to battery No. 2n-1 form the second sub-battery pack, and n is an integer greater than or equal to 3. Method 600 includes steps 601 to 609.

[0073] In step 601, a second equalization threshold is determined to meet the user's equalization requirement between the first sub-battery pack and the second sub-battery pack.

[0074] In step 602, a first pair of switching tubes coupled between the positive electrode of battery No. n and the negative electrode of battery No. 1 is used to couple the intermediate node of the first pair of switching tubes to the first end of the first inductor. The first pair of switching tubes and the first inductor form a first energy conversion unit.

[0075] In step 603, a second pair of switching tubes coupled between the positive electrode of battery No. 2n-1 and the negative electrode of battery No. n is used to couple the intermediate node of the second pair of switching tubes to the first end of the second inductor, where the second pair of switching tubes and the second inductor form a second energy conversion unit.

[0076] In step 604, the voltages of the first sub-battery pack and the second sub-battery pack are obtained, and it is determined whether the inter-group equalization requirement between the first sub-battery pack and the second sub-battery pack comes. In one embodiment, the difference between the voltage of the first sub-battery pack and the voltage of the second sub-battery pack is compared with the second equalization threshold. If the difference is greater than the second equalization threshold, it is determined that the inter-group equalization requirement between the first sub-battery pack and the second sub-battery pack comes, and step 605 is entered.

[0077] In step 605, the second end of the first inductor is coupled to the negative electrode of battery No. n, and the second end of the second inductor is coupled to the positive electrode of battery No. n.

[0078] Further, in step 606, it is determined that the voltage of the first sub-battery pack exceeds the voltage of the second sub-battery pack by a second equalization threshold. In step 607, in response to the voltage of the first sub-battery pack exceeding the voltage of the second sub-battery pack by a second equalization threshold, both the first energy transfer unit and the second energy transfer unit are configured to operate in a boost mode.

[0079] In step 608, it is determined that the voltage of the second sub-battery pack exceeds the voltage of the first sub-battery pack by a second equalization threshold. In step 609, in response to the voltage of the second sub-battery pack exceeding the voltage of the first sub-battery pack by a second equalization threshold, both the first energy transfer unit and the second energy transfer unit are configured to operate in a buck mode.

[0080] Although the above embodiments all involve the situation where the battery with the highest battery voltage discharges other batteries in the battery pack, which is exactly the opposite of the situation where other batteries in the battery pack charge the battery with the lowest voltage in the battery pack. Therefore, the embodiments of the present invention only need to be slightly changed to be applied to a battery pack balancing system or method with the lowest target battery voltage. When the voltage of the target battery is the lowest, the balancing system and method for the battery pack also meet the spirit and protection scope of the present invention.

[0081] Figure 13 FIG. is a schematic diagram of an integrated circuit IC1 for balancing a battery pack according to an embodiment of the present invention. As Figure 13 shown, the integrated circuit IC1 is used to balance the voltages of n series-connected single cells in the battery pack 101. The integrated circuit IC1 includes a plurality of conduction paths 106B, a first switch pair composed of a high-side switch transistor QH and a low-side switch transistor QL, and a plurality of pins. The plurality of pins include a ground pin GND coupled to the negative electrode of the first cell C1, pins C2 to C4 respectively coupled to the negative electrodes of the second cell C2 to the fifth cell C5, a pin V+ coupled to the positive electrode of the fifth cell, a first power pin P1 coupled to the intermediate node of the first switch pair, and a second power pin P2 coupled to the first power pin P1 through an external inductor L1. The first switch pair and the inductor L1 form an energy conversion unit 105B.

[0082] In Figure 13 the shown embodiment, the second power pin P2 is coupled to the positive electrode of the first target battery or the negative electrode of the second target battery in a time-sharing manner. Wherein the first target battery is the single cell with the highest or lowest voltage among the first to n-1th cells, and the second target battery is the single cell with the highest or lowest voltage among the second to nth cells.

[0083] Specifically, when the second power pin P2 is coupled to the positive electrode of the first target battery, in response to the highest voltage of the first target battery, the energy transfer unit 105B is configured to operate in a boost mode; in response to the lowest voltage of the first target battery, the energy transfer unit 105B is configured to operate in a buck mode.

[0084] Furthermore, when the second power pin P2 is coupled to the negative electrode of the second target battery, in response to the highest voltage of the second target battery, the energy transfer unit 105B is configured to operate in a buck mode; in response to the lowest voltage of the second target battery, the energy transfer unit 105B is configured to operate in a boost mode.

[0085] In the specification or claims, related terms such as first and second may merely distinguish one entity or action from another entity or action, and do not necessarily or imply any such relationship or order between these entities or actions. Numerical sequences such as "first", "second", "third", etc. merely refer to different individuals among a plurality, and do not imply any order or sequence, unless the claim language specifically limits it. The order of the text in any one claim does not mean that the processing steps must be carried out in a temporal or logical order according to this order, unless the claim language specifically provides otherwise. Without departing from the scope of the present invention, these processing steps may be interchanged in any order, as long as such interchange does not cause the claim language to be contradictory and does not result in logical absurdity.

[0086] Although the present invention has been described with reference to several exemplary embodiments, it should be understood that the terms used are illustrative and exemplary, rather than restrictive. Since the present invention can be embodied in many forms without departing from the spirit or essence of the invention, it should be understood that the above embodiments are not limited to any of the foregoing details, but should be broadly construed within the spirit and scope defined by the appended claims. Therefore, all variations and modifications falling within the scope of the claims or their equivalents should be covered by the appended claims.

Claims

1. A system for balancing a battery pack, the battery pack comprising a No. 1 battery, a No. 2 battery, ..., a No. n battery connected in series in sequence, wherein n is an integer greater than or equal to 3, the system include: An energy transfer unit, comprising a first switch tube pair and a first inductor, wherein the first switch tube pair is coupled between the positive electrode of the nth battery and the negative electrode of the first battery, an intermediate node of the first switch tube pair is coupled to a first end of the first inductor, and a second end of the first inductor is coupled to a positive electrode of a first target battery or a negative electrode of a second target battery in a time-sharing manner, wherein the first target battery is a single cell with the highest or lowest voltage among batteries No. 1 to No. n-1, and the second target battery is a single cell with the highest or lowest voltage among batteries No. 2 to No. n; as well as The first gate driver and the second gate driver generate a first drive signal and a second drive signal in response to the PWM signal to drive the first switch tube pair to switch operation, wherein when the second end of the first inductor is coupled to the positive electrode of the first target battery, in response to the voltage of the first target battery being the highest, the energy transfer unit is configured to operate in a boost mode, and in response to the voltage of the first target battery being the lowest, the energy transfer unit is configured to operate in a buck mode, and when the second end of the first inductor is coupled to the negative electrode of the second target battery, in response to the voltage of the second target battery being the highest, the energy transfer unit is configured to operate in a buck mode, and in response to the voltage of the second target battery being the lowest, the energy transfer unit is configured to operate in a boost mode.

2. The system as claimed in claim 1, wherein the first target battery and the second target battery are the same single battery among batteries No. 2 to No. n-1, and a positive electrode and a negative electrode of the single battery are coupled to the second end of the first inductor in a time-sharing manner.

3. A system as described in claim 2, wherein the energy transfer unit operates in a buck mode for a first time period and in a boost mode for a second time period, and when the average voltage of the battery in a charging state in the buck mode is less than the average voltage of the battery in a charging state in the boost mode, the ratio of the first time period to the second time period is increased.

4. A system as described in claim 2, wherein the energy transfer unit operates in a boost mode during a third time period and in a buck mode during a fourth time period, wherein when the average voltage of the battery in a discharging state in the boost mode is less than the average voltage of the battery in a discharging state in the buck mode, the ratio of the third time period to the fourth time period is reduced.

5. The system of claim 1, further comprising n-1 conduction paths, wherein in response to a balancing requirement within the battery pack, one of the n-1 conduction paths is selected to be turned on to provide an electrical connection between the positive electrode of the first target battery and the second end of the first inductor.

6. The system of claim 5, wherein each of the n-1 conduction paths comprises a pair of bidirectional switches.

7. A system as described in claim 5, wherein the conduction path between the positive electrode of battery No. 1 and the second end of the first inductor includes a unidirectional switch, the conduction path between the negative electrode of battery No. n and the second end of the first inductor includes a unidirectional switch, and the other conduction paths in the n-1 conduction paths each include a pair of bidirectional switches.

8. A system for balancing stacked battery packs, the stacked battery pack comprising battery No. 1, battery No. 2, ..., battery No. 2n-1 connected in series in sequence, wherein batteries No. 1 to n constitute a first sub-battery group, batteries No. n to 2n-1 constitute a second sub-battery group, and n is an integer greater than or equal to 3. The system include: A first energy transfer unit, comprising a first switch tube pair and a first inductor, wherein the first switch tube pair is coupled between the positive electrode of the nth battery and the negative electrode of the first battery, an intermediate node of the first switch tube pair is coupled to a first end of the first inductor, and a second end of the first inductor is coupled to a positive electrode of a first target battery or a negative electrode of a second target battery in a time-sharing manner, wherein the first target battery is a single cell with the highest or lowest voltage among batteries No. 1 to No. n-1, and the second target battery is a single cell with the highest or lowest voltage among batteries No. 2 to No. n; A second energy transfer unit, comprising a second switch tube pair and a second inductor, wherein the second switch tube pair is coupled between the positive electrode of the 2n-1 battery and the negative electrode of the n battery, an intermediate node of the second switch tube pair is coupled to the first end of the second inductor, and a second end of the second inductor is time-divisionally coupled to the positive electrode of a third target battery or the negative electrode of a fourth target battery, wherein the third target battery is a single cell with the highest or lowest voltage among the n to 2n-2 batteries, and the fourth target battery is a single cell with the highest or lowest voltage among the n+1 to 2n-1 batteries; The first gate driver and the second gate driver respectively generate the first and second driving signals to drive the first switch tube pair to switch operation, wherein when the second end of the first inductor is coupled to the positive electrode of the first target battery, in response to the voltage of the first target battery being the highest, the first energy transfer unit operates in a boost mode, and in response to the voltage of the first target battery being the lowest, the first energy transfer unit operates in a buck mode, and when the second end of the first inductor is coupled to the negative electrode of the second target battery, in response to the voltage of the second target battery being the highest, the first energy transfer unit operates in a buck mode, and in response to the voltage of the second target battery being the lowest, the first energy transfer unit operates in a boost mode; as well as The third gate driver and the fourth gate driver respectively generate third and fourth drive signals to drive the second switch tube pair to switch operation, wherein when the second end of the second inductor is coupled to the positive electrode of the third target battery, in response to the third target battery having the highest voltage, the second energy transfer unit operates in a boost mode, and in response to the third target battery having the lowest voltage, the second energy transfer unit operates in a buck mode, and when the second end of the second inductor is coupled to the negative electrode of the fourth target battery, in response to the fourth target battery having the highest voltage, the second energy transfer unit operates in a buck mode, and in response to the fourth target battery having the lowest voltage, the second energy transfer unit operates in a boost mode.

9. The system of claim 8, wherein the first target battery and the second target battery are the same single battery among batteries No. 2 to No. n-1, and a positive electrode and a negative electrode of the single battery are coupled to the second end of the first inductor in a time-sharing manner.

10. The system according to claim 9, wherein the first energy transfer unit operates in a buck mode during a first time period and in a boost mode during a second time period, and when the average voltage of the batteries in the first sub-battery pack in the charging state is less than the average voltage of the batteries in the charging state in the boost mode, the ratio of the first time period to the second time period is increased.

11. The system according to claim 8, further comprising a plurality of first conduction paths and a plurality of second conduction paths, wherein: in response to an equalization demand within the first sub-battery pack, one of the plurality of first conduction paths is selected to conduct, providing an electrical connection between the positive electrode of the first target battery and the second end of the first inductor; and in response to an equalization demand within the second sub-battery pack, one of the plurality of second conduction paths is selected to conduct, providing an electrical connection between the positive electrode of the third target battery and the second end of the second inductor.

12. The system according to claim 11, wherein in response to an equalization demand between the first sub-battery pack and the second sub-battery pack, the second end of the first inductor is coupled only to the negative electrode of the nth battery, and the second end of the second inductor is coupled only to the positive electrode of the nth battery.

13. The system according to claim 12, wherein: in response to the voltage of the first sub-battery pack exceeding the voltage of the second sub-battery pack by an equalization threshold, both the first energy transfer unit and the second energy transfer unit are configured to operate in a boost mode; and in response to the voltage of the second sub-battery pack exceeding the voltage of the first sub-battery pack by an equalization threshold, both the first energy transfer unit and the second energy transfer unit are configured to operate in a buck mode.

14. A method for equalizing a battery pack, the battery pack including a first battery, a second battery, ······, an nth battery connected in series in sequence, where n is an integer greater than or equal to 3, the method comprises: determining the single battery with the highest voltage among the first battery to the nth battery; using a first switching transistor pair coupled between the positive electrode of the nth battery and the negative electrode of the first battery, coupling the intermediate node of the first switching transistor pair to the first end of the first inductor, wherein the first switching transistor pair and the first inductor form an energy conversion unit; if the voltage of the first battery is the highest, coupling the second end of the first inductor only to the positive electrode of the first battery, and configuring the energy conversion unit to operate in a boost mode; if the voltage of the nth battery is the highest, coupling the second end of the first inductor only to the negative electrode of the nth battery, and configuring the energy conversion unit to operate in a buck mode; and if the voltage of the single target battery among the second battery to the (n - 1)th battery is the highest, coupling the second end of the first inductor only to the negative electrode of the target battery, configuring the energy conversion unit to operate in a buck mode during a first time period, and after the first time period, coupling the second end of the first inductor only to the positive electrode of the target battery, and configuring the energy conversion unit to operate in a boost mode during a second time period.

15. The method according to claim 14, wherein when the average voltage of the batteries in the charging state in the buck mode is less than the average voltage of the batteries in the charging state in the boost mode, the ratio of the first time period to the second time period is increased.

16. A method for equalizing a battery pack, the battery pack including a No. 1 battery, a No. 2 battery, ······, a No. n battery connected in series in sequence, where n is an integer greater than or equal to 3, the method includes: determining the single cell with the lowest voltage among the No. 1 to No. n batteries; using a first switch pair coupled between the positive electrode of the No. n battery and the negative electrode of the No. 1 battery, and coupling the middle node of the first switch pair to the first end of a first inductor, where the first switch pair and the first inductor form an energy conversion unit; if the voltage of the No. 1 battery is the lowest, coupling the second end of the first inductor only to the positive electrode of the No. 1 battery, and configuring the energy conversion unit to operate in a buck mode; if the voltage of the No. n battery is the lowest, coupling the second end of the first inductor only to the negative electrode of the No. n battery, and configuring the energy conversion unit to operate in a boost mode; and if the voltage of the single target cell among the No. 2 to No. n - 1 batteries is the lowest, coupling the second end of the first inductor only to the negative electrode of the target cell, configuring the energy conversion unit to operate in a boost mode within a first time period, and after the first time period, coupling the second end of the first inductor only to the positive electrode of the target cell, and configuring the energy conversion unit to operate in a buck mode within a second time period.

17. The method according to claim 16, wherein when the average voltage of the batteries in a discharge state in the boost mode is less than the average voltage of the batteries in a discharge state in the buck mode, the ratio of the first time period to the second time period is increased.

18. A method for equalizing a battery pack, the battery pack including a No. 1 battery, a No. 2 battery, ······, a No. 2n - 1 battery connected in series in sequence, where the No. 1 to No. n batteries form a first sub - battery pack, and the No. n to No. 2n - 1 batteries form a second sub - battery pack, n is an integer greater than or equal to 3, the method includes: using a first switch pair coupled between the positive electrode of the No. n battery and the negative electrode of the No. 1 battery, and coupling the middle node of the first switch pair to the first end of a first inductor, where the first switch pair and the first inductor form a first energy conversion unit; using a second switch pair coupled between the positive electrode of the No. 2n - 1 battery and the negative electrode of the No. n battery, and coupling the middle node of the second switch pair to the first end of a second inductor, where the second switch pair and the second inductor form a second energy conversion unit; and in response to the inter - group equalization requirement between the first sub - battery pack and the second sub - battery pack, coupling the second end of the first inductor to the negative electrode of the No. n battery, and coupling the second end of the second inductor to the positive electrode of the No. n battery.

19. The method according to claim 18, wherein: in response to the voltage of the first sub - battery pack exceeding the voltage of the second sub - battery pack by an equalization threshold, configuring both the first energy transfer unit and the second energy transfer unit to operate in a boost mode; and in response to the voltage of the second sub - battery pack exceeding the voltage of the first sub - battery pack by an equalization threshold, configuring both the first energy transfer unit and the second energy transfer unit to operate in a buck mode.

20. An integrated circuit for equalizing a battery pack, the battery pack including a No. 1 battery, a No. 2 battery, ······, a No. n battery connected in series in sequence, where n is an integer greater than or equal to 3, the integrated circuit includes: a first battery pin, coupled to the negative electrode of the No. 1 battery; The second battery pin to the (n + 1)-th battery pin are sequentially coupled to the positive electrodes of the 1st to n-th batteries respectively; The first power pin is coupled to the second power pin via an inductor; The second power pin is coupled to the positive electrode of the first target battery or the negative electrode of the second target battery in a time-sharing manner, where the first target battery is the single battery with the highest or lowest voltage among the 1st to (n - 1)-th batteries, and the second target battery is the single battery with the highest or lowest voltage among the 2nd to n-th batteries; The first switch pair is coupled between the (n + 1)-th battery pin and the first battery pin, where the middle node of the first switch pair is coupled to the first power pin, and the first switch pair and the inductor form an energy conversion unit; and When the second power pin is coupled to the positive electrode of the first target battery, in response to the highest voltage of the first target battery, the energy transfer unit operates in a boost mode, and in response to the lowest voltage of the first target battery, the energy transfer unit operates in a buck mode. When the second power pin is coupled to the negative electrode of the second target battery, in response to the highest voltage of the second target battery, the energy transfer unit operates in a buck mode, and in response to the lowest voltage of the second target battery, the energy transfer unit operates in a boost mode.

21. The integrated circuit according to claim 20, further comprising n - 1 conduction paths, wherein in response to an equalization demand within the battery pack, one of the n - 1 conduction paths is selected to conduct, providing an electrical connection between the positive electrode of the first target battery and the second power terminal 。

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