System and integrated circuit for balancing battery packs and stacked battery packs and method

Abstract

Systems, integrated circuits and methods for balancing battery packs and stacked battery packs are disclosed. A battery pack includes n number of series connected batteries, n being an integer greater than or equal to 3. One of the systems includes: an energy transfer unit including an inductor and a first pair of switching transistors coupled between a positive terminal of the n-th battery and a negative terminal of the 1-st battery, a middle node of the first pair of switching transistors being coupled to a first terminal of the inductor, a second terminal of the inductor being time-divisionally coupled to either a positive terminal of a first target battery or a negative terminal of a second target battery, the first target battery being a battery with the highest voltage among the 1-st to the (n-1)-th batteries, the second target battery being a battery with the highest voltage among the 2-nd to the n-th batteries; and first and second gate drivers driving the first pair of switching transistors to switch operation. The energy transfer unit operates in a step-up mode when the second terminal of the inductor is coupled to the positive terminal of the first target battery, and operates in a step-down mode when the second terminal of the inductor is coupled to the negative terminal of the second target battery.

Description

Technical Field

[0001] This invention relates to a switching power supply, and more particularly to a system, integrated circuit, and method for balancing and stacking battery packs. Background Technology

[0002] Battery packs typically consist of several individual cells connected in series. Differences in charging state, impedance, and temperature characteristics among these cells can lead to imbalances. This imbalance reduces the overall capacity and shortens the lifespan of the battery pack. Therefore, battery balancing circuits are needed to regulate this imbalance, maintaining the pack's capacity and extending its lifespan.

[0003] Common battery balancing circuits in the prior art include passive resistor balancing circuits and active balancing circuits that include capacitors, inductors, or transformers. Passive resistor balancing circuits dissipate excess energy through resistors, resulting in low efficiency and high heat generation. Meanwhile, common active balancing circuits that include capacitors, inductors, or transformers are also unacceptable to customers due to their circuit complexity and lack of stability.

[0004] Figure 1 This refers to the passive resistor equalization circuit 10 in the prior art. For example... Figure 1 As 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 higher-voltage battery cells are discharged through the bypass resistor and bypass FET, thereby equalizing the voltage between the battery cells in the battery pack. Although this technical solution is relatively simple, it can only regulate the higher-voltage battery cells, and excess energy can only be dissipated as heat, resulting in low equalization efficiency.

[0005] Figure 2 This refers to an existing active equalization circuit 20 that includes capacitors. For example... Figure 2 As shown, in the active equalization circuit 20, the capacitor continuously switches between two adjacent battery cells to balance the capacity of each battery cell in the battery pack. Although this technical solution is more efficient than passive resistor equalization, it still dissipates a large amount of energy during capacitor charging, and the energy can only be transferred between adjacent battery cells.

[0006] Figure 3 This refers to an existing active equalization circuit 30 that includes a transformer. For example... Figure 3 As shown, in the equalization circuit 30, energy can be transferred between the battery pack and each battery cell within the battery pack. This technical solution offers fast equalization speed, but the use of a transformer increases circuit cost and size.

[0007] Figure 4 This refers to an existing active equalization circuit 40 that includes an inductor. For example... Figure 4 As shown, the equalization circuit 40 performs energy transfer in buck-boost converter mode. In this technical solution, energy can only be transferred between two adjacent battery cells, resulting in a slow equalization speed and low equalization efficiency. Summary of the Invention

[0008] This invention provides a system, integrated circuit, and method for balancing battery packs and stacked battery packs, achieving good balancing results 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 batteries 1, 2, ..., n connected in series, where n is an integer greater than or equal to 3. The system includes an energy transfer unit comprising a first pair of switches and a first inductor. The first pair of switches is coupled between the positive terminal of battery n and the negative terminal of battery 1. The middle node of the first pair of switches is coupled to the first terminal of the first inductor. The second terminal of the first inductor is time-divisionally coupled to the positive terminal of a first target battery or the negative terminal of a second target battery. The first target battery is the single cell with the highest or lowest voltage among batteries 1 to n-1, and the second target battery is the single cell with the highest or lowest voltage among batteries 2 to n. The first gate driver and the second gate driver, in response to the PWM signal, generate a first drive signal and a second drive signal to drive the first switching transistor pair to switch operation. When the second terminal of the first inductor is coupled to the positive terminal of the first target battery, the energy transfer unit is configured to operate in boost mode in response to the highest voltage of the first target battery, and is configured to operate in buck mode in response to the lowest voltage of the first target battery. When the second terminal of the first inductor is coupled to the negative terminal of the second target battery, the energy transfer unit is configured to operate in buck mode in response to the highest voltage of the second target battery, and is configured to operate in boost mode in response to the lowest voltage of the second target battery.

[0010] According to the present invention, a system for balanced stacked battery packs is also proposed. The stacked battery pack includes batteries 1, 2, ..., 2n-1 connected in series, wherein batteries 1 to n constitute a first sub-battery pack, and batteries n to 2n-1 constitute a second sub-battery pack, where n is an integer greater than or equal to 3. The system includes a first energy transfer unit, comprising a first pair of switches and a first inductor, wherein the first pair of switches is coupled between the positive terminal of battery n and the negative terminal of battery 1, the middle node of the first pair of switches is coupled to the first terminal of the first inductor, and the second terminal of the first inductor is time-divisionally coupled to the positive terminal of a first target battery or the negative terminal of a second target battery. The first target battery is the single cell with the highest or lowest voltage among batteries numbered 1 to n-1, and the second target battery is the single cell with the highest or lowest voltage among batteries numbered 2 to n. The second energy transfer unit includes a second pair of switches and a second inductor. The second pair of switches is coupled between the positive terminal of battery number 2n-1 and the negative terminal of battery number n. The middle node of the second pair of switches is coupled to the first terminal of the second inductor. The second terminal of the second inductor is time-divisionally coupled to the positive terminal of a third target battery or the negative terminal of a fourth target battery. The third target battery is the single cell with the highest or lowest voltage among batteries numbered n to 2n-2, and the fourth target battery is the single cell with the highest or lowest voltage among batteries numbered n+1 to 2n-1. The first energy transfer unit operates in boost mode when the second terminal of the first inductor is coupled to the positive terminal of the first target battery, and in buck mode when the voltage of the first target battery is at its highest. The second terminal of the first inductor is coupled to the negative terminal of the second target battery, and in buck mode when the voltage of the second target battery is at its lowest. The second energy transfer unit operates in boost mode, and the third and fourth gate drivers generate third and fourth drive signals respectively to drive the second switch pair to switch operation. When the second terminal of the second inductor is coupled to the positive terminal of the third target battery, the second energy transfer unit operates in boost mode in response to the highest voltage of the third target battery, and operates in buck mode in response to the lowest voltage of the third target battery. When the second terminal of the second inductor is coupled to the negative terminal of the fourth target battery, the second energy transfer unit operates in buck mode in response to the highest voltage of the fourth target battery, and operates in boost mode in response to the lowest voltage of the fourth target battery.

[0011] According to the present invention, a method for balancing a battery pack is proposed. The battery pack includes batteries 1, 2, ..., n connected in series, where n is an integer greater than or equal to 3. The method includes: determining the individual battery with the highest voltage among batteries 1 to n; using a first switch pair coupled between the positive terminal of battery n and the negative terminal of battery 1, and coupling the middle node of the first switch pair to the first terminal of a first inductor, wherein the first switch pair and the first inductor constitute an energy conversion unit; if battery 1 has the highest voltage, coupling only the second terminal of the first inductor to... The energy conversion unit is configured to operate in boost mode at the positive terminal of battery number 1; if battery number n has the highest voltage, the second terminal of the first inductor is coupled only to the negative terminal of battery number n, and the energy conversion unit is configured to operate in buck mode; and if the voltage of a single target battery among batteries number 2 to n-1 is the highest, the second terminal of the first inductor is coupled only to the negative terminal of the target battery, and the energy conversion unit is configured to operate in buck mode for a first duration, and after the first duration, the second terminal of the first inductor is coupled only to the positive terminal of the target battery, and the energy conversion unit is configured to operate in boost mode for a second duration.

[0012] According to the present invention, a method for balancing a battery pack is proposed. The battery pack includes batteries 1, 2, ..., n connected in series, where n is an integer greater than or equal to 3. The method includes: determining the individual battery with the lowest voltage among batteries 1 to n; using a first switch pair coupled between the positive terminal of battery n and the negative terminal of battery 1, and coupling the middle node of the first switch pair to the first terminal of a first inductor, wherein the first switch pair and the first inductor constitute an energy conversion unit; if battery 1 has the lowest voltage, coupling only the second terminal of the first inductor to... The energy conversion unit is configured to operate in buck mode at the positive terminal of battery number 1; if battery number n has the lowest voltage, the second terminal of the first inductor is coupled only to the negative terminal of battery number n, and the energy conversion unit is configured to operate in boost mode; and if the voltage of a single target battery among batteries number 2 to n-1 is the lowest, the second terminal of the first inductor is coupled only to the negative terminal of the target battery, and the energy conversion unit is configured to operate in boost mode for a first duration, and after the first duration, the second terminal of the first inductor is coupled only to the positive terminal of the target battery, and the energy conversion unit is configured to operate in buck mode for a second duration.

[0013] According to the present invention, a method for balancing a battery pack is also proposed. The battery pack includes batteries 1, 2, ..., 2n-1 connected in series, wherein batteries 1 to n constitute a first sub-battery pack, and batteries n to 2n-1 constitute a second sub-battery pack, where n is an integer greater than or equal to 3. The method includes: using a first pair of switches coupled between the positive terminal of battery n and the negative terminal of battery 1, and coupling the middle node of the first pair of switches to the first terminal of a first inductor, wherein the first pair of switches and the first inductor constitute a first energy conversion unit; using a second pair of switches coupled between the positive terminal of battery 2n-1 and the negative terminal of battery n, and coupling the middle node of the second pair of switches to the first terminal of a second inductor, wherein the second pair of switches and the second inductor constitute a second energy conversion unit; and responding to the inter-pack balancing requirement between the first and second sub-battery packs, coupling the second terminal of the first inductor to the negative terminal of battery n, and coupling the second terminal of the second inductor to the positive terminal of battery n.

[0014] According to the present invention, an integrated circuit for a balanced battery pack is further proposed. The battery pack includes batteries 1, 2, ..., n connected in series, where n is an integer greater than or equal to 3. The integrated circuit includes: a first battery pin coupled to the negative terminal of battery 1; second battery pins to the (n+1)th battery pin, respectively coupled to the positive terminals of batteries 1 to n; a first power pin coupled to a second power pin via an inductor; and a second power pin time-divisionally coupled to the positive terminal of a first target battery or the negative terminal of a second target battery, wherein the first target battery is the single cell with the highest or lowest voltage among batteries 1 to n-1, and the second target battery is the single cell with the highest or lowest voltage among batteries 2 to n. A single battery cell; a first pair of switches coupled between the (n+1)th battery pin and the first battery pin, wherein the middle node of the first pair of switches is coupled to the first power pin, and the first pair of switches and the inductor constitute an energy conversion unit; and wherein when the second power pin is coupled to the positive terminal of the first target battery, the energy transfer unit operates in boost mode in response to the highest voltage of the first target battery, and operates in buck mode in response to the lowest voltage of the first target battery; and when the second power pin is coupled to the negative terminal of the second target battery, the energy transfer unit operates in buck mode in response to the highest voltage of the second target battery, and operates in boost mode in response to the lowest voltage of the second target battery.

[0015] According to embodiments of the present invention, balancing a battery pack of n series-connected batteries requires only one inductor, one pair of switches, and n-1 conduction paths, saving costs while meeting the balancing requirements of the battery packs. Furthermore, according to embodiments of the present invention, voltage balancing between battery packs can be quickly achieved in response to balancing needs, thus meeting user requirements. Attached Figure Description

[0016] Figure 1 This refers to the passive resistor equalization circuit 10 in the prior art;

[0017] Figure 2 The existing active equalization circuit 20 includes capacitors;

[0018] Figure 3 The existing active equalization circuit 30 includes a transformer;

[0019] Figure 4 The existing active equalization circuit 40 includes an inductor;

[0020] Figure 5 This is a schematic block diagram of a system 100 for balancing a battery pack according to an embodiment of the present invention.

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

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

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

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

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

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

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

[0028] Figure 12 This is a flowchart of a method 600 for equalizing the stacking of batteries according to an embodiment of the present invention;

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

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

[0031] Throughout this specification, references to “an embodiment,” “an example,” or “an example” mean that a particular feature, structure, or characteristic described in connection with that embodiment or example is included in at least one embodiment of the invention. Therefore, the phrases “in an embodiment,” “in an embodiment,” “an example,” or “an example” appearing in various places throughout the specification do not necessarily refer to the same embodiment or example. Furthermore, specific features, structures, or characteristics can be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. Moreover, those skilled in the art will understand that the accompanying drawings provided herein are for illustrative purposes and are not necessarily drawn to scale. It should be understood that when an element is referred to as “connected to” or “coupled to” another element, it can be a direct connection or coupling to the other element or there may be intermediate elements. Conversely, when an element is referred to as “directly connected to” or “directly coupled to” another element, there are no intermediate elements. The same reference numerals indicate the same elements. The term “and / or” as used herein includes any and all combinations of one or more of the associated listed items.

[0032] Figure 5 This is a schematic block diagram of a system 100 for balancing a battery pack according to an embodiment of the present invention. Figure 5 As shown, system 100 includes a battery pack 101 and a battery management system 102. The battery pack 101 has a plurality of individual cells connected in series between battery pack terminals V+ and V-. The battery pack 101 includes battery number 1 C1, battery number 2 C2, ..., battery number n Cn connected in series, where n is an integer greater than or equal to 3. Figure 5 In the embodiment shown, the battery pack 101 includes five individual battery cells C1 to C5 connected in series.

[0033] like Figure 5As shown, the battery management system 102 includes a sampling unit 103, a control unit 104, an energy transfer unit 105, multiple conduction paths 106, a first gate driver 107, and a second gate driver 108. The sampling unit 103 is connected to each individual cell in the battery pack 101 and is used to collect the voltage of each individual cell. The control unit 104 is connected to the sampling unit 103 and is used to receive and monitor the voltage of each series-connected individual cell, determine its state within the entire battery pack 101, and identify the target cell with the highest or lowest voltage, thereby determining whether the battery pack balancing startup conditions are met.

[0034] In one embodiment, the method for the control unit 104 to initiate battery pack equalization is as follows: The total average voltage of the entire battery pack 101 is calculated, and the difference between the voltage of the highest-voltage individual cell and the total average voltage is calculated. When the voltage of the target cell exceeds a preset equalization threshold of the total average voltage of the battery pack 101, it is determined that the equalization requirement for the individual cell has arrived. The control unit 104 outputs a gating control signal MUX to select one of the multiple conduction paths 106, and outputs a PWM signal to the first gate driver 107 and the second gate driver 108. In one embodiment, the method for the control unit 104 to end battery pack equalization is as follows: After equalization is completed, the total average voltage of the entire battery pack 101 is recalculated, and the difference between the voltage of the target cell with the highest voltage and the total average voltage is calculated. When the difference is less than the preset equalization threshold, the equalization termination condition is met. The control unit 104 no longer outputs the gating 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 terminal (i.e., battery pack terminal V+) of battery n and the negative terminal (i.e., battery pack terminal V-) of battery 1. 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 time-divisionally coupled to the positive terminal of a first target battery or the negative terminal of a second target battery, wherein the first target battery is the single cell with the highest voltage among batteries 1 to n-1, and the second target battery is the single cell with the highest voltage among batteries 2 to n. When the voltage of the target battery exceeds the total average voltage by a certain margin, 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 target battery with the highest battery voltage. In one embodiment, the second end of inductor L1 is coupled to the positive terminal of the first target battery during a first time period t1, and coupled to the negative terminal 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, converting it into complementary, non-overlapping first drive signal GH and second drive signal GL, which are used to directly drive the high-side switch QH and the low-side switch QL of the first switching pair to switch between them. This is because the output capability of the control unit 104 is limited and cannot directly drive the high-side switch QH and the low-side switch QL in the energy transfer unit 105. The first gate driver 107 and the second gate driver 108 are needed to improve the driving capability in order to control the on and off of the first switching pair.

[0037] When the second terminal of inductor L1 is coupled to the positive terminal of the first target battery, the energy transfer unit 105 is configured to operate in boost mode; when the second terminal of inductor L1 is coupled to the negative terminal of the second target battery, the energy transfer unit 105 is configured to operate in buck mode. Through this balancing method, the energy is transferred from the target cell with the highest voltage in the battery pack 101 to the other cells in the battery pack 101, causing the target battery voltage to converge towards the target average voltage.

[0038] In one embodiment, the first target battery is battery number 1, meaning battery number 1 has the highest voltage. The second terminal of inductor L1 is electrically connected to the positive terminal of the first target battery, i.e., the positive terminal of battery number 1. At this time, the energy transfer unit 105 is configured to operate in boost mode.

[0039] In another embodiment, the second target battery is battery number n, meaning battery number n has the highest voltage. The second terminal of inductor L1 is electrically connected to the negative terminal of the second target battery, i.e., the negative terminal of battery number n. In this case, the energy transfer unit 105 is configured to operate in buck mode.

[0040] In another embodiment, the first target battery and the second target battery are the same single cell from battery size 2 to n-1, with the positive and negative terminals of the single cell time-divisionally coupled to the second terminal of inductor L1. Specifically, taking battery size 3 with the highest voltage as an example, the second terminal of inductor L1 is first connected to the negative terminal of battery size 3, and energy transfer unit 105 is configured to operate in buck mode. After the buck mode lasts for a first duration t1, the second terminal of inductor L1 is recoupled to the positive terminal of battery size 3, and energy transfer unit 105 is configured to operate in boost mode, which lasts for a second duration t2.

[0041] Figure 6 This is a circuit diagram of a system 100A for balancing a battery pack according to an embodiment of the present invention. Figure 6As shown, the multiple conduction paths 106A include four switches S1 to S4, which are selected and controlled by the selection control signal MUX. The energy transfer unit 105A includes a first switch pair composed 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 individual 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 individual battery cells C1 to C5 connected in series. Correspondingly, multiple conduction paths 106A include four switches S1 to S4 to time-divisionally couple the second terminal of inductor L1 to the positive or negative terminal of the target battery. In one embodiment, a gating control signal MUX can switch switches S1 to S4 between fully on and fully off states.

[0043] The following example uses battery No. 3 as the target cell with the highest voltage. (Refer to the appendix.) Figure 7A and 7B Let me describe in detail the working principle of the energy transfer unit 105A.

[0044] Figure 7A This is an energy transfer unit 105A operating in buck mode according to an embodiment of the present invention. When the battery voltage of battery C3 is at its highest and exceeds a preset threshold of the total average voltage, the second terminal of inductor L1 is coupled to the negative terminal of battery C3, and energy transfer unit 105A enters buck mode operation, as shown below. Figure 7A As shown. The high-side switch QH is turned on first. QH, inductor L1, and batteries C3 through C5 form a discharge circuit, meaning C3 through C5 are all discharging, supplying energy to inductor L1. Inductor L1 converts the released electrical energy into stored energy. Subsequently, QH is turned off, and QL is turned on. Inductor L1, batteries C1 and C2 form a charging circuit, charging C1 and C2, transferring the stored energy to C1 and C2. Then, QH is turned on again, QL is turned off, and C3 through C5 discharge again. This process repeats continuously. During this process, QL and QL alternately turn on, and the entire buck mode lasts for the first duration t1.

[0045] Figure 7B This is an energy transfer unit 105A operating in boost mode according to an embodiment of the present invention. After a first duration t1, as... Figure 7BAs shown, the second terminal of inductor L1 is disconnected from the negative terminal of battery C3 and reconnected to the positive terminal of battery C3, and the energy transfer unit 105A enters boost mode. The low-side switch QL is turned on first, forming a discharge circuit with inductor L1 and batteries C1 through C3. At this time, C1 through C3 are discharging, discharging into inductor L1, which converts the released electrical energy into stored energy. Subsequently, the low-side switch QL is turned off, and the high-side switch QH is turned on, forming a charging circuit with inductor L1, battery C4, and battery C5. Therefore, in boost mode, C4 and C5 are charging. Afterward, the low-side switch QL is turned on again, and the high-side switch QH is turned off, repeating this process continuously. During this process, the high-side switch QL and the low-side switch QL are turned on alternately, and the entire boost mode lasts for the first duration t2.

[0046] Assuming all batteries have approximately the same impedance, and the current flowing through inductor L1 is I, approximately 2 / 5 I of the current flows out of the batteries in the discharging state, and 3 / 5 I of the current flows into the batteries in the charging state. Specifically, in buck mode, the batteries in the charging state are battery 1 (C1) and battery 2 (C2), while in boost mode, the batteries in the charging state are battery 4 (C4) and battery 5 (C5). It can be seen that battery 3 (C3), as the target battery, is always in the discharging state. In one embodiment, if the average voltage of the batteries in the charging state in buck mode is less than the average voltage of the batteries in the charging state in 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 enables rapid balancing of large currents within the battery pack. Compared to passive balancing, the time required for active balancing is significantly reduced, thus improving balancing efficiency. This balancing method further extends the discharge time of the battery pack 101 to the load, improves discharge efficiency, extends the service life of the battery pack 101, and ultimately achieves energy saving and emission reduction.

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

[0049] like Figure 8 As shown, the multiple conduction paths 106B include four switches S1 to S4 to provide electrical connections between the second terminal of the first inductor L1 and the positive terminal of the first target battery. In one embodiment, each of the switches S1 to S4 includes two N-channel MOSFETs connected in anti-phase series. Figure 8 In the embodiment shown, switch S4, which can be coupled to the negative terminal of battery C5, and switch S1, which can be coupled to the positive terminal of battery C1, include a unidirectional switch, and S3 and S2 each include two bidirectional switches connected in series in opposite phases.

[0050] As can be seen, the integrated circuit (IC) topology used in this invention is simple and low-cost. Balancing n series-connected batteries requires only one inductor, one pair of switches, and n-1 conduction paths.

[0051] Figure 9 This is a schematic diagram of a system 200 for balancing stacked battery packs according to an embodiment of the present invention. Figure 9 As 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, multiple first conduction paths 1061, multiple second conduction paths 1062, and first to fourth gate drivers 107-110. The battery pack 101A has 2n-1 individual cells connected in series between battery pack terminals V+ and V-. The battery pack 101A includes battery C1 (number 1), battery C2 (number 2), ..., battery C(2n-1) (number 2n-1) connected in series, where n is an integer greater than or equal to 3. Figure 9In the illustrated embodiment, battery pack 101A includes nine individual batteries C1 to C9 connected in series. Batteries C1 to C5 constitute a first sub-battery pack (i.e., C1 to C5), and batteries C5 to C9 constitute a second sub-battery pack (i.e., C5 to C9). Multiple first conduction paths 1061 include four switches S1 to S4, and multiple second conduction paths 1062 include four switches S5 to S6.

[0052] Sampling unit 103A is connected to each individual cell in battery pack 101A to collect the voltage of each individual cell. Control unit 104A is connected to sampling unit 103A to receive and monitor the voltage of each series-connected individual cell, determine its state in its respective sub-cell pack, determine the target cell with the highest or lowest voltage in each sub-cell pack, and then determine whether the starting conditions for cell balancing within the battery pack are met.

[0053] In one embodiment, when the balancing demand between the two battery packs is met, the control unit 104A outputs a gating 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. At the same time, it outputs a gating 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 pair of switches and a first inductor L1. The first pair of switches is coupled between the positive terminal of battery n and the negative terminal of battery 1, and includes a high-side switch QH and a low-side switch QL. The middle node of the first pair of switches is coupled to the first terminal of the first inductor L1. The second terminal of the first inductor L1 is time-divisionally coupled to the positive terminal of a first target battery or the negative terminal of a second target battery. The first target battery is the single cell with the highest voltage among batteries 1 to n-1, and the second target battery is the single cell with the highest voltage among batteries 2 to n.

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

[0056] In one embodiment, the first target battery and the second target battery are the same single cell from size 2 to n-1 batteries, with the positive and negative terminals of the single cell time-divisionally coupled to the second terminal of the first inductor L1. For example, battery C3 has the highest voltage, and the second terminal of the first inductor L1 is coupled to the negative terminal of battery C3. The first energy transfer unit 1051 operates in buck mode for a first duration t1. Subsequently, the second terminal of the first inductor L1 is coupled to the positive terminal of battery C3, and the first energy transfer unit 1051 operates in boost mode for a second duration t2. When the average voltage of the batteries (C1 and C2) in the first battery pack (C1-C5) in buck mode is less than the average voltage of the batteries (C4 and C5) in boost mode, the ratio of the first duration t1 to the second duration t2 is increased.

[0057] The second energy transfer unit 1052 includes a second pair of switches and a second inductor L2. The second pair of switches is coupled between the positive terminal of battery 2n-1 and the negative terminal of battery n, and includes a high-side switch QH1 and a low-side switch QL. The middle node of the second pair of switches is coupled to the first terminal of the second inductor L2. The second terminal of the second inductor L2 is time-divisionally coupled to the positive terminal of a third target battery or the negative terminal of a fourth target battery. The third target battery is the single cell with the highest voltage among batteries n to 2n-2, and the fourth target battery is the single cell with the highest voltage among batteries n+1 to 2n-1.

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

[0059] In one embodiment, the third and fourth target batteries are the same single cell from size n+1 to 2n-2, with the positive and negative terminals of this single cell time-divisionally coupled to the second terminal of the second inductor L2. For example, if battery C7 (size 7) has the highest voltage, the second terminal of the second inductor L2 is coupled to the negative terminal of battery C7, and the second energy transfer unit 1052 operates in buck mode for a third duration t3. Subsequently, the second terminal of the second inductor L2 is coupled to the positive terminal of battery C7, and the second energy transfer unit 1052 operates in boost mode for a fourth duration t4. When the average voltage of the batteries (C5 and C6) in the second battery pack (C5-C9) in buck mode is less than the average voltage of the batteries (C8 and C9) in boost mode, the ratio of the third duration t3 to the fourth duration t4 is increased.

[0060] Furthermore, the control unit 104A also monitors the voltage difference between the first and second sub-battery packs according to user needs, and when the voltage difference between the two exceeds the second equalization threshold, it determines that the need for equalization between the two sub-battery packs has arrived, and then activates the equalization mechanism between the two sub-battery packs.

[0061] Figure 10 This is a circuit diagram of a system 200A for a balanced stacked battery pack according to another embodiment of the present invention. Figure 10 As shown, in response to the balancing requirement between the first and second battery sub-packs, the control unit 104A provides a gating control signal MUX1 to turn on the switches S4 in the multiple first conduction paths 1061, coupling the second terminal of the first inductor L1 only to the negative terminal of battery n. Simultaneously, the control unit 104A provides a gating control signal MUX2 to turn on the switches S5 in the multiple second conduction paths 1062, coupling the second terminal of the second inductor L2 only to the positive terminal of battery n.

[0062] If the voltage of the first battery pack exceeds the voltage of the second battery pack by a second equalization threshold, in response to the PWM1 signal, the first energy transfer unit 1051 operates in 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 boost mode under the drive of the third gate driver 109 and the fourth gate driver 110.

[0063] If the voltage of the second battery pack exceeds the voltage of the first battery pack minus a second equalization threshold, in response to the PWM1 signal, the first energy transfer unit 1051 operates in 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 buck mode under the drive of the third gate driver 109 and the fourth gate driver 110.

[0064] Figure 11 This is a flowchart of a method 500 for balancing 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, 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 requirements for the series-connected batteries in the battery pack.

[0066] In step 502, the voltage of each individual cell is obtained, and the individual cell with the highest voltage among cells 1 to n is determined.

[0067] In step 503, a first switch pair coupled between the positive terminal of battery n and the negative terminal of battery 1 is used, and the middle node of the first switch pair is coupled to the first end of the first inductor, wherein the first switch pair and the first inductor constitute an energy conversion unit.

[0068] In step 504, if the voltage of battery 1 is the highest, then proceed to step 541, whereby the second terminal of the first inductor is coupled only to the positive terminal of battery 1, and the energy conversion unit is configured to operate in boost mode (step 542).

[0069] In step 505, if the voltage of battery n is the highest, then proceed to step 551, whereby the second terminal of the first inductor is coupled only to the negative terminal of battery n, and the energy conversion unit is configured to operate in buck mode (step 552).

[0070] In step 506, if the target cell has the highest voltage among cells 2 through n-1, then proceed to step 561, where the second terminal of the first inductor is coupled only to the negative terminal of the target cell, and the energy conversion unit is configured to operate in buck mode for the first duration (step 562). After the first duration, proceed to step 563, where the second terminal of the first inductor is coupled only to the positive terminal of the target cell, and the energy conversion unit is configured to operate in boost mode for the second duration (step 564).

[0071] In one embodiment, when the average voltage of a battery in buck mode is less than the average voltage of a battery in boost mode, the ratio of the first duration to the second duration is increased.

[0072] Figure 12This is a flowchart of a method 600 for balancing stacked battery packs according to an embodiment of the present invention. The battery pack includes battery No. 1, battery No. 2, ..., 2n-1 connected in series, wherein batteries No. 1 to No. 2n constitute a first sub-battery pack, and batteries No. 2n to 2n-1 constitute a second sub-battery pack, where 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 requirements between the first and second sub-battery packs.

[0074] In step 602, a first switch pair coupled between the positive terminal of battery n and the negative terminal of battery 1 is used, and the middle node of the first switch pair is coupled to the first terminal of the first inductor. The first switch pair and the first inductor constitute the first energy conversion unit.

[0075] In step 603, a second switch pair coupled between the positive terminal of battery 2n-1 and the negative terminal of battery n is used, and the middle node of the second switch pair is coupled to the first end of the second inductor, wherein the second switch pair and the second inductor constitute a second energy conversion unit.

[0076] In step 604, the voltages of the first and second battery sub-groups are obtained, and it is determined whether an inter-group balancing requirement has been met. In one embodiment, the difference between the voltages of the first and second battery sub-groups is compared with a second balancing threshold. If the difference is greater than the second balancing threshold, it is determined that an inter-group balancing requirement has been met, and the process proceeds to step 605.

[0077] In step 605, the second end of the first inductor is coupled to the negative terminal of the n-th battery, and the second end of the second inductor is coupled to the positive terminal of the n-th battery.

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

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

[0080] Although the above embodiments all involve the scenario where the battery with the highest voltage discharges the other batteries in the battery pack, this is the opposite of the scenario where the other batteries in the battery pack charge the battery with the lowest voltage. Therefore, the embodiments of the present invention can be applied to a battery pack balancing system or method with a target battery having the lowest voltage with only slight modifications. The balancing system and method for the battery pack when the target battery has the lowest voltage also satisfy the spirit and scope of the present invention.

[0081] Figure 13 This is a schematic diagram of an integrated circuit IC1 for balancing a battery pack according to an embodiment of the present invention. Figure 13 As shown, integrated circuit IC1 is used to balance the voltage of n individual cells connected in series within battery pack 101. Integrated circuit IC1 includes multiple conduction paths 106B, a first switch pair consisting of a high-side switch QH and a low-side switch QL, and multiple pins. These pins include a ground pin GND coupled to the negative terminal of battery C1, pins C2 to C4 coupled to the negative terminals of batteries C2 through C5 respectively, a pin V+ coupled to the positive terminal of battery C5, 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 via an external inductor L1. The first switch pair and inductor L1 constitute an energy conversion unit 105B.

[0082] exist Figure 13 In the illustrated embodiment, the second power pin P2 is time-divisionally coupled to the positive terminal of the first target battery or the negative terminal of the second target battery. The first target battery is the single cell with the highest or lowest voltage among batteries numbered 1 to n-1, and the second target battery is the single cell with the highest or lowest voltage among batteries numbered 2 to n.

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

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

[0085] In the specification or claims, related terms such as "first" and "second" may merely distinguish one entity or action from another, without necessarily implying any relationship or order between these entities or actions. Numerical orders such as "first," "second," and "third" merely refer to different individuals among a plurality and do not imply any order or sequence, unless specifically defined in the claim language. The order of the text in any claim does not imply that the processing steps must be performed in a provisional or logical order according to such an order, unless specifically specified in the claim language. Without departing from the scope of the invention, these processing steps may be interchanged in any order, provided that such interchange does not contradict the claim language and does not result in logical absurdity.

[0086] Although the invention has been described with reference to several exemplary embodiments, it should be understood that the terminology used is descriptive and exemplary, and not restrictive. Since the 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 interpreted broadly 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 balanced stacking of battery packs, the stacked battery pack comprising batteries 1, 2, ..., 2n-1 connected in series, wherein batteries 1 to n constitute a first sub-battery pack, batteries n to 2n-1 constitute a second sub-battery pack, and n is an integer greater than or equal to 3, the system comprising: The first integrated circuit includes a first pair of switches and n-1 first conduction paths, wherein the first pair of switches is coupled between the positive terminal of battery n and the negative terminal of battery 1, the middle node of the first pair of switches is coupled to the first end of the first inductor, and in response to the balancing requirements within the first battery pack, the second end of the first inductor is time-divisionally coupled to the positive terminal of the first target battery or the negative terminal of the second target battery, wherein the first target battery is the single cell with the highest or lowest voltage among batteries 1 to n-1, and the second target battery is the single cell with the highest or lowest voltage among batteries 2 to n, wherein the first pair of switches and the first inductor constitute a first energy conversion unit; The second integrated circuit includes a second pair of switches and n-1 second conduction paths. The second pair of switches is coupled between the positive terminal of battery 2n-1 and the negative terminal of battery n. The middle node of the second pair of switches is coupled to the first terminal of the second inductor. In response to the balancing requirements within the second battery pack, the second terminal of the second inductor is time-divisionally coupled to the positive terminal of the third target battery or the negative terminal of the fourth target battery. The third target battery is the single cell with the highest or lowest voltage among batteries n to 2n-2, and the fourth target battery is the single cell with the highest or lowest voltage among batteries n+1 to 2n-1. The second pair of switches and the second inductor constitute a second energy conversion unit. as well as In response to the balancing requirement between the first and second battery sub-packs, one of the n-1 first conduction paths in the first integrated circuit is selected to conduct, and the second end of the first inductor is coupled only to the negative terminal of battery n. Similarly, one of the n-1 second conduction paths in the second integrated circuit is selected to conduct, and the second end of the second inductor is coupled only to the positive terminal of battery n.

2. The system of claim 1, wherein the first target battery and the second target battery are the same single cell from battery number 2 to n-1, and the positive and negative terminals of the single cell are time-divisionally coupled to the second terminal of the first inductor.

3. The system of claim 2, wherein the first energy transfer unit operates in buck mode for a first duration and in boost mode for a second duration, wherein when the average voltage of the batteries in the first battery pack in the buck mode is less than the average voltage of the batteries in the boost mode, the ratio of the first duration to the second duration is increased.

4. The system as claimed in claim 1, wherein: In response to the voltage of the first battery pack exceeding the voltage equalization threshold of the second battery pack, both the first energy transfer unit and the second energy transfer unit are configured to operate in boost mode; and In response to the voltage of the second battery pack exceeding the voltage equalization threshold of the first battery pack, both the first energy transfer unit and the second energy transfer unit are configured to operate in buck mode.

5. The system of claim 2, wherein the first energy transfer unit operates in boost mode for a third duration and in buck mode for a fourth duration, wherein when the average voltage of the batteries in the first battery pack in the boost mode is less than the average voltage of the batteries in the buck mode, the ratio of the third duration to the fourth duration is reduced.

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

7. The system of claim 1, wherein the conduction path between the positive terminal of battery 1 and the second terminal of the first inductor includes a one-way switch, the conduction path between the negative terminal of battery n and the second terminal of the first inductor includes a one-way switch, and the other conduction paths in the n-1 first conduction paths each include a pair of bidirectional switches.

8. A method for using a system for a balanced stacked battery pack as described in claim 1, the stacked battery pack comprising batteries 1, 2, ..., 2n-1 connected in series, wherein batteries 1 to n constitute a first sub-battery pack, batteries n to 2n-1 constitute a second sub-battery pack, and n is an integer greater than or equal to 3, the method comprising: Using a first switch pair coupled between the positive terminal of battery n and the negative terminal of battery 1 in a first integrated circuit, the middle node of the first switch pair is coupled to the first end of the first inductor, wherein the first switch pair and the first inductor constitute a first energy conversion unit. The second switch pair in the second integrated circuit is coupled between the positive terminal of the 2n-1 battery and the negative terminal of the n battery, and the middle node of the second switch pair is coupled to the first end of the second inductor, wherein the second switch pair and the second inductor constitute the second energy conversion unit. In response to the balancing requirement within the first battery pack, one of the n-1 first conduction paths in the first integrated circuit is selected to conduct, providing an electrical connection between the positive terminal of the first target battery and the second terminal of the first inductor; In response to the balancing requirements within the second battery pack, one of the n-1 second conduction paths in the second integrated circuit is selected to conduct, providing an electrical connection between the positive terminal of the third target battery and the second terminal of the second inductor; as well as In response to the inter-group balancing requirement between the first and second battery sub-packs, one of the n-1 first conduction paths in the first integrated circuit is selected to conduct, coupling the second terminal of the first inductor to the negative terminal of battery n, and one of the n-1 second conduction paths in the second integrated circuit is selected to conduct, coupling the second terminal of the second inductor to the positive terminal of battery n.

9. The method of claim 8, wherein: In response to the voltage of the first battery pack exceeding the voltage equalization threshold of the second battery pack, both the first energy transfer unit and the second energy transfer unit are configured to operate in boost mode; and In response to the voltage of the second battery pack exceeding the voltage equalization threshold of the first battery pack, both the first energy transfer unit and the second energy transfer unit are configured to operate in buck mode.

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