Method and circuit for controlling balanced charging and discharging of battery string

Abstract

The invention relates to the technical field of battery equalization control, in particular to a method and circuit for controlling equalization charging and discharging of a battery string, and the method comprises the steps: obtaining the sampling voltage at the two ends of each single battery and the sampling current in a charging and discharging loop of the battery string; and then, according to the sampling voltage and the sampling current, respectively controlling the conduction states of a first switch and a second switch corresponding to the corresponding single batteries, so as to select the single batteries meeting the charging and discharging requirements to be respectively charged and discharged. The single battery can be independently charged and discharged, and finally, complete charging and complete discharging of each single battery are realized; the limitation that in an energy storage battery system, a single battery or a very small number of single batteries are completely utilized is solved; a single single battery can be charged and discharged, or a plurality of single batteries can be charged and discharged together; and the problem of unbalanced charging and discharging of the battery system is solved, so that the maximum utilization of battery resources is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of battery equalization control, and particularly to a method and a circuit for controlling the equalized charge and discharge of a battery string. Background Art

[0002] In today's society, the problems of environmental pollution and energy crisis are becoming increasingly prominent. New energy technologies have developed rapidly, and there are more and more products powered by batteries. In some fields with high power supply voltage requirements, such as electric vehicles, the voltage of a single battery often fails to meet the power supply requirements. Therefore, several batteries are usually connected in series to form a battery pack for use.

[0003] In the currently series-connected rechargeable battery system, since the charge and discharge currents of the batteries are the same, when one of the batteries is fully charged or discharged, the circuit will stop charging and discharging. At this time, only one or very few single cells are fully charged and discharged, resulting in the incomplete same charge of each current single cell. Even if the charges are the same, there will be differences after multiple charge and discharge processes, resulting in incomplete charging and discharging of each single cell.

[0004] In view of this, overcoming the defects of the existing technology is an urgent problem to be solved in this technical field. Summary of the Invention

[0005] The technical problem to be solved by the present invention is how to solve the problem of unbalanced charge and discharge of the battery system, so as to maximize the utilization of battery resources.

[0006] The present invention adopts the following technical solutions:

[0007] In a first aspect, a method for controlling the equalized charge and discharge of a battery string is provided, which is implemented in a charge and discharge loop of the battery string. Among them, a first switch is respectively arranged between the positive electrode of the charge and discharge module for controlling the charge and discharge of the battery string and the positive electrode of each single cell in the battery string, and a second switch is respectively arranged between the negative electrode of the charge and discharge module and the negative electrode of each single cell in the battery string. The method includes:

[0008] Obtain the sampled voltage across each single cell and the sampled current in the charge and discharge loop of the battery string;

[0009] According to the sampled voltage and the sampled current, respectively control the conduction states of the first switch and the second switch corresponding to the respective single cells, so as to select and charge and discharge the single cells that meet the charge and discharge requirements respectively.

[0010] Preferably, the method further includes:

[0011] In the charging state, respectively judge whether the state of charge of each single cell is in a fully charged state or an uncharged state according to the sampled voltage and the sampled current;

[0012] Disconnect the first switch and the second switch at both ends of the first monomer battery in a fully charged state, conduct the first switch and the second switch at both ends of the second monomer battery in an uncharged state, and control the charge and discharge module to charge the second monomer battery until it is detected that the state of charge of the second monomer battery reaches a fully charged state; or, obtain the connection relationship of the second monomer battery in an uncharged state. If there are at least two second monomer batteries forming a series relationship, form at least two second monomer batteries into a series battery pack, and conduct the first switch corresponding to the series battery pack and the second switch corresponding to the series battery pack.

[0013] Preferably, the method further includes:

[0014] In the discharge state, respectively judge whether the state of charge of each monomer battery is in a fully discharged state or an incompletely discharged state according to the sampled voltage and the sampled current;

[0015] Disconnect the first switch and the second switch at both ends of the third monomer battery in a fully discharged state, conduct the first switch and the second switch at both ends of the fourth monomer battery in an incompletely discharged state, and control the charge and discharge module to discharge the fourth monomer battery until it is detected that the state of charge of the fourth monomer battery reaches a fully discharged state; or, obtain the connection relationship of the second monomer battery in an incompletely discharged state. If there are at least two second monomer batteries forming a series relationship, form at least two second monomer batteries into a series battery pack, and conduct the first switch corresponding to the series battery pack and the second switch corresponding to the series battery pack.

[0016] Preferably, an energy storage module is provided between each first switch and the positive electrode of the corresponding monomer battery, and each energy storage module is provided with a corresponding control switch. The method further includes:

[0017] When the charge and discharge module cannot support charging the remaining monomer batteries in an uncharged state, turn off the charge and discharge module, and respectively obtain the charge amount of each monomer battery according to the sampled voltage and the sampled current;

[0018] Compare the charge amounts between adjacent two monomer batteries, and by controlling the conduction states of the first switch, the second switch and the control switch of the corresponding energy storage module, enable the monomer battery with a larger charge amount to charge the corresponding energy storage unit;

[0019] After charging the energy storage unit for a preset time, by controlling the conduction states of the first switch, the second switch and the control switch of the corresponding energy storage unit, enable the charged energy storage unit to charge the monomer battery with a smaller charge amount.

[0020] Preferably, the method further includes:

[0021] When the charge and discharge module can only support charging the remaining single battery cell, select the battery cell with the lowest voltage for charging according to a preset period to continuously increase the power of the battery cell with the lowest voltage and reduce the voltage difference between each battery cell.

[0022] Preferably, the method further includes:

[0023] During the discharge process of the battery string, evaluate the maximum discharge current that each battery cell can accept, and control the charge and discharge module to perform series discharge according to the minimum value among the maximum discharge currents.

[0024] Preferably, the method further includes: before the charge and discharge process of the battery string, detect the contact resistance of each battery cell in the battery string, specifically including:

[0025] Obtain the open-circuit voltage of each battery cell in the battery string in the open-circuit state;

[0026] Output a short-term constant current through a constant current source to charge the battery string, and obtain the sampled voltage across each battery cell during the charging process;

[0027] Obtain the contact resistance of the corresponding battery cell according to the open-circuit voltage, the short-term constant current, and the sampled voltage.

[0028] Preferably, the method further includes:

[0029] During the charging process, the calculation method of the sampled voltage is: Vc = Vm - Ic * Rc;

[0030] During the discharge process, the calculation method of the sampled voltage is: Vc = Vm + Ic * Rc;

[0031] Wherein, Vc is the sampled voltage, Vm is the voltage value actually measured across each battery cell, Ic is the sampling current, and Rc is the contact resistance corresponding to the corresponding battery cell.

[0032] In a second aspect, a circuit for controlling the balanced charge and discharge of a battery string is provided, which is used to implement the method for controlling the balanced charge and discharge of a battery string as described in the first aspect, including: a control module, a charge and discharge module, a voltage sampling module, a current sampling module, and a switch module. The positive electrode of the charge and discharge module is connected to the positive electrode of the battery string, and the negative electrode of the charge and discharge module is connected to the negative electrode of the battery string;

[0033] The switch module includes a first switch disposed between the positive electrode of each battery cell and the positive electrode of the charge and discharge module, and a second switch disposed between the negative electrode of each battery cell and the negative electrode of the charge and discharge module;

[0034] The sampling points of the voltage sampling module are respectively connected to the positive and negative electrodes of each single battery; the current acquisition module is connected in series in the main circuit of the charge and discharge module;

[0035] The control module is respectively connected to the control ends of each switch in the charge and discharge module, the voltage sampling module, the current sampling module, and the switch module;

[0036] The charge and discharge module is used to charge or discharge the battery string according to the instructions of the control module;

[0037] The voltage sampling module is used to respectively obtain the sampling voltages at both ends of each single battery, and the current sampling module is used to obtain the sampling current in the main circuit of the charge and discharge of the battery string;

[0038] The control module is used to respectively control the conduction states of the first switch and the second switch corresponding to the corresponding single battery according to the sampling voltage and the sampling current, so as to select to charge and discharge the single batteries that meet the charge and discharge requirements respectively, so as to realize the charge and discharge balance of each single battery in the charge and discharge state of the battery string.

[0039] Preferably, an energy storage module is provided in the charge and discharge circuit where each single battery is located, and the energy storage module includes an energy storage unit, a first control switch, and a second control switch;

[0040] One ends of the first control switch and the second control switch are respectively connected to one end of the first switch, the other end of the first control switch is connected to one end of the energy storage unit, and the other end of the energy storage unit and the other end of the second control switch are respectively connected to the positive electrode of each single battery.

[0041] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0042] The present invention obtains the sampling voltages at both ends of each single battery and the sampling current in the charge and discharge circuit of the battery string; then respectively controls the conduction states of the first switch and the second switch corresponding to the corresponding single battery according to the sampling voltage and the sampling current, so as to select to charge and discharge the single batteries that meet the charge and discharge requirements respectively; it can realize the charging and discharging of a single single battery separately, and finally realize the full charge and full discharge of each single battery; it solves the limitation that only one or very few single batteries can be fully utilized in the energy storage battery system; it can charge and discharge a single single battery, or multiple single batteries can be charged and discharged together; it solves the problem of unbalanced charge and discharge of the battery system, thereby maximizing the utilization of battery resources. Description of the Drawings

[0043] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0044] Figure 1 It is a schematic structural diagram of a battery string assembly structure provided by an embodiment of the present invention;

[0045] Figure 2 It is a schematic structural diagram of a battery string assembly structure provided by an embodiment of the present invention;

[0046] Figure 3 It is a schematic structural diagram of a connection conductive component in a battery string assembly structure provided by an embodiment of the present invention;

[0047] Figure 4 It is a schematic structural diagram of a connection conductive component in a battery string assembly structure provided by an embodiment of the present invention;

[0048] Figure 5 It is a schematic structural diagram of a connection component in a battery string assembly structure provided by an embodiment of the present invention;

[0049] Figure 6 It is a schematic structural diagram of a connection piece in a battery string assembly structure provided by an embodiment of the present invention;

[0050] Figure 7 It is a schematic structural diagram of a connection piece in a battery string assembly structure provided by an embodiment of the present invention;

[0051] Figure 8 It is a schematic partial structural diagram of a battery string assembly structure provided by an embodiment of the present invention;

[0052] Figure 9 It is a schematic structural diagram of a fixing ring in a battery string assembly structure provided by an embodiment of the present invention;

[0053] Figure 10 It is a schematic structural diagram of a fixing ring in a battery string assembly structure provided by an embodiment of the present invention;

[0054] Figure 11 It is a schematic structural diagram of a battery conductive structure and an external conductive point structure in a battery string assembly structure provided by an embodiment of the present invention;

[0055] Figure 12 It is a schematic structural diagram of a connection piece in a battery string assembly structure provided by an embodiment of the present invention;

[0056] Figure 13It is a schematic structural diagram of a connecting piece in a battery string assembly structure provided by an embodiment of the present invention;

[0057] Figure 14 It is a schematic structural diagram of a battery conductive structure and an external conductive point structure in a battery string assembly structure provided by an embodiment of the present invention;

[0058] Figure 15 It is a schematic structural diagram of a connecting component in a battery string assembly structure provided by an embodiment of the present invention;

[0059] Figure 16 It is a schematic structural diagram of a connecting conductive component in a battery string assembly structure provided by an embodiment of the present invention;

[0060] Figure 17 It is a schematic structural diagram of a connecting component in a battery string assembly structure provided by an embodiment of the present invention;

[0061] Figure 18 It is a schematic structural diagram of a battery conductive structure and an external conductive point structure in a battery string assembly structure provided by an embodiment of the present invention;

[0062] Figure 19 It is a schematic structural diagram of a battery conductive structure and an external conductive point structure in a battery string assembly structure provided by an embodiment of the present invention;

[0063] Figure 20 It is a schematic structural diagram of a fixing ring in a battery string assembly structure provided by an embodiment of the present invention;

[0064] Figure 21 It is a schematic structural diagram of a connecting piece in a battery string assembly structure provided by an embodiment of the present invention;

[0065] Figure 22 It is a schematic structural diagram of a connecting component in a battery string assembly structure provided by an embodiment of the present invention;

[0066] Figure 23 It is a schematic structural diagram of a battery string assembly structure provided by an embodiment of the present invention;

[0067] Figure 24 It is a partial schematic structural diagram of a battery string assembly structure provided by an embodiment of the present invention;

[0068] Figure 25 It is a schematic structural diagram of a locking component in a battery string assembly structure provided by an embodiment of the present invention;

[0069] Figure 26 It is a partial schematic structural diagram of a battery string assembly structure provided by an embodiment of the present invention;

[0070] Figure 27It is a schematic structural diagram of a locking component in a battery string assembly structure provided by an embodiment of the present invention;

[0071] Figure 28 It is a schematic structural diagram of a housing in a battery string assembly structure provided by an embodiment of the present invention;

[0072] Figure 29 It is a schematic structural diagram of a housing in a battery string assembly structure provided by an embodiment of the present invention;

[0073] Figure 30 It is a schematic structural diagram of a total wiring cover in a battery string assembly structure provided by an embodiment of the present invention;

[0074] Figure 31 It is a schematic structural diagram of a battery string provided by an embodiment of the present invention;

[0075] Figure 32 It is a schematic flowchart of a method for controlling the balanced charging and discharging of a battery string provided by an embodiment of the present invention;

[0076] Figure 33 It is a schematic flowchart of a method for balanced charging of a battery string during charging provided by an embodiment of the present invention;

[0077] Figure 34 It is a schematic diagram of the relationship between the core temperature and the state of charge of the battery provided by an embodiment of the present invention;

[0078] Figure 35 It is a schematic flowchart of a method for balanced discharging of a battery string during discharging provided by an embodiment of the present invention;

[0079] Figure 36 It is another schematic diagram of the relationship between the core temperature and the state of charge of the battery provided by an embodiment of the present invention;

[0080] Figure 37 It is a schematic flowchart of a battery mutual charging process for balancing battery power provided by an embodiment of the present invention;

[0081] [[ID=3\7]]Figure 38 It is a schematic structural diagram of a circuit for battery mutual charging provided by an embodiment of the present invention;

[0082] Figure 39 It is a schematic flowchart of a process for obtaining contact resistance provided by an embodiment of the present invention;

[0083] Figure 40 It is a schematic structural diagram of a circuit for controlling the balanced charging and discharging of a battery string provided by an embodiment of the present invention;

[0084] Figure 41 It is another schematic structural diagram of a circuit for controlling the balanced charging and discharging of a battery string provided by an embodiment of the present invention;

[0085] Figure 42 It is another structural schematic diagram of a circuit for controlling the balanced charge and discharge of a battery string provided by an embodiment of the present invention;

[0086] Figure 43 It is a structural schematic diagram of an energy storage module provided by an embodiment of the present invention;

[0087] Figure 44 It is a structural schematic diagram of a single battery charging an energy storage unit provided by an embodiment of the present invention;

[0088] Figure 45 It is a structural schematic diagram of charging a single battery by an energy storage unit provided by an embodiment of the present invention;

[0089] Figure 46 It is a structural schematic diagram of an integrated circuit board attached to a single battery provided by an embodiment of the present invention;

[0090] Figure 47 It is a structural schematic diagram of a voltage sampling module provided by an embodiment of the present invention;

[0091] Figure 48 It is a structural schematic diagram of a voltage mapping unit provided by an embodiment of the present invention.

[0092] In all the drawings, the same reference numerals are used to denote the same elements or structures, where:

[0093] 1. Connecting rod; 11. First connecting rod; 12. Second connecting rod; 2. Connecting and conducting component; 21. Connecting component; 211. Connecting piece; 2110. Insert piece; 21101. First through hole; 2111. Placing groove; 2112. Opening; 2113. First elastic piece; 2114. Second elastic piece; 212. Fixed ring; 2120. Slot; 2121. Protrusion; 21211. First sub-protrusion part; 21212. Second sub-protrusion part; 21213. First protrusion; 21214. Second protrusion; 21210. Duct; 212101. First sub-duct; 212102. Second sub-duct; 2122. Buckle; 21221. First groove; 21222. Second groove; 2123. Notch; 22. Battery conducting structure; 221. First conducting piece; 222. Second conducting piece; 223. First connecting part; 224. Second connecting part; 225. Extension part; 23. External conducting structure; 3. Battery; 4. External circuit; 5. Locking component; 51. Connecting rod; 511. Second through hole; 512. Third through hole; 513. Abutting block; 52. First screw; 53. Second screw; 54. Third screw; 55. Fourth screw; 6. Outer shell; 61. Cylindrical shell; 62. Bottom cover; 63. Wiring cover; 631. Wiring cap; 632. Pressure relief cap; 7. Wiring harness. Detailed implementation manners

[0094] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0095] Unless otherwise required by the context, throughout the specification and claims, the term "comprising" is interpreted in an open, inclusive sense, i.e., "including, but not limited to". In the description of the specification, the terms "one embodiment", "some embodiments", "exemplary embodiments", "examples", "specific examples" or "some examples", etc., are intended to indicate that specific features, structures, materials or characteristics related to the embodiment or example are included in at least one embodiment or example of the present disclosure. The schematic representations of the above terms are not necessarily directed to the same embodiment or example. In addition, the specific features, structures, materials or characteristics may be included in any one or more embodiments or examples in any suitable manner, that is, although they may be carried in the above terms of the embodiment or example due to reasons such as the order of appearance and position, etc., but it does not limit that they can be carried by one embodiment or example in a combined manner.

[0096] In the description of the present invention, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the embodiments of the present disclosure, unless otherwise stated, the meaning of "a plurality" is two or more. In addition, for example, in the description, for the same type of nouns, the method of adding "A" and "B" at the end is used to describe them as two independent individuals. In this case, the features defined with "A" and "B" are only used for the purpose of distinguishing similar individuals and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features.

[0097] When describing some embodiments, the expressions "coupled", "coupled to" and "connected" and their derivatives may be used. For example, when describing some embodiments, the term "connected" may be used to indicate that two or more components have direct physical or electrical contact with each other. Another example is that when describing some embodiments, the term "coupled to" may be used to indicate that two or more components have direct physical or electrical contact. However, the term "connected" or "coupled" may also mean that two or more components do not have direct contact with each other, but still cooperate or interact with each other, such as "optical path coupling" and "wireless connection". The embodiments disclosed herein are not necessarily limited to the content of the present invention.

[0098] In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0099] Embodiment 1:

[0100] Embodiment 1 of the present invention provides a battery string assembly structure, as Figure 1 and Figure 2 shown, which includes at least one series connection rod 1 and a plurality of connecting conductive components 2; each connecting conductive component 2 is connected in series on the series connection rod 1; and a reserved space is provided between every two connecting conductive components 2 for accommodating a battery 3 and making direct contact with the positive or negative electrode of the battery 3; each connecting conductive component 2 is also used for connecting an external circuit 4 to realize the coupling between the battery 3 and the external circuit 4.

[0101] In actual use, the series connection rod 1 can be one; for ensuring stability, the number of the series connection rods 1 can be two, and two series connection rods 1 form a relatively stable bracket, as Figure 1 and Figure 2 shown, 7 connecting conductive components 2 can be connected in series on one bracket for accommodating 6 batteries 3. Among them, Figure 1 is a schematic diagram in the state where the battery is not installed, Figure 2Schematic diagram with the battery installed.

[0102] In this embodiment, a series connection rod 1 is used to form a connection bracket, and each connection and conductive component 2 forms a connector for coupling the battery 3 and the external circuit 4. Thus, the coupling of the battery 3 and the external circuit 4 can be achieved without welding the battery 3 and the external circuit 4. In the implementation mode of this embodiment, when a corresponding battery has a problem, the battery can be directly taken out and replaced without disassembling the series connection rod 1, other batteries in the battery string, and the connection and conductive component 2, thereby saving manpower and material resources.

[0103] In an alternative implementation mode, as Figure 3 and Figure 4 shown, the connection and conductive component 2 includes a connection component 21, a battery conductive structure 22, and an external conductive structure 23 extended from the battery conductive structure 22; the battery conductive structure 22 is installed on the connection component 21, and the connection component 21 is serially connected on the series connection rod 1; the battery conductive structure 22 is in direct contact with the positive or negative electrode of the battery 3; the external conductive structure 23 is used to connect the external circuit 4 to achieve the coupling of the battery 3 and the external circuit 4.

[0104] Among them, Figure 3 and Figure 4 are respectively the front schematic diagram and the back schematic diagram of the connection and conductive component 2. The serial connection of the connection component 21 on the series connection rod 1 can be achieved through through holes, channels, or other fixing structures (such as buckles, etc.).

[0105] In a preferred implementation mode, as Figure 5 shown, the connection component 21 includes a connection piece 211 and a fixing ring 212; as Figure 6 shown, at least one insertion piece 2110 is provided at at least one end of the connection piece 211; as Figure 9 shown, at least one slot 2120 is provided on the ring wall of the fixing ring 212, and the slot 2120 matches the insertion piece 2110; the insertion piece 2110 is inserted into the slot 2120 to install the connection piece 211 inside the ring of the fixing ring 212 and make the connection piece 211 perpendicular to the axial direction of the fixing ring 212 (i.e., the direction of the series connection rod 1); as Figure 10 shown, at least one protrusion 2121 is provided on the outer wall of the fixing ring 212, and a channel 21210 parallel to the axial direction of the fixing ring 212 is provided on the protrusion 2121, and the series connection rod 1 is inserted into the channel 21210 to serially connect the connection component 21; the connection piece 211 is used to provide an installation position for the battery conductive structure 22.

[0106] It should be noted that the fixing ring 212 may not be a full ring in actual use, so as to leave an opening for the connecting piece 211 to be installed in the ring. The number of the inserting pieces 2110 can be multiple, and the number of the slots 2120 can be multiple, such as Figure 6 In the embodiment, there are two inserting tabs 2110, one at each end of the inserting tab 2110. Correspondingly, there are also two slots 2120 on the fixing ring 212. This allows the fixing ring 212 to form a stable structure after the connecting tab 211 is installed on it. In actual use, the fixing ring 212 may have a certain degree of elasticity to allow the fixing ring 212 to be opened, allowing the connecting tab 211 to enter the ring, and the inserting tabs 2110 to be inserted into the corresponding slots 2120.

[0107] Furthermore, the width of the insert 2110 (i.e. Figure 7 W1 in the figure) is smaller than the width of the connecting piece 211 body (i.e. Figure 7 W2) in Figure 7 As shown, W1<W2, the size of the slot 2120 is adapted to the width of the inserting piece 2110, so that after the inserting piece 2110 is inserted into the slot 2120, the connecting piece 211 body is stuck in the ring.

[0108] In a preferred embodiment, Figure 8 As shown, the number of the serial rods 1 can be two, namely the first serial rod 11 and the second serial rod 12, and the number of the protrusions 2121 is also two, namely the first protrusion 21213 and the second protrusion 21214, and the two protrusions 2121 are arranged opposite to each other, the first protrusion 21213 and the second protrusion 21214 are respectively arranged on both sides of the fixing ring 212, the first serial rod 11 passes through the hole 21210 on the first protrusion 21213, and the second serial rod 12 passes through the hole 21210 on the second protrusion 21214, so that the first serial rod 11, the second serial rod 12 and the multiple connected conductive components 2 in series together constitute a stable, non-rotating bracket structure.

[0109] In a specific application scenario, such as Figure 11 As shown, the battery conductive structure 22 includes a first conductive sheet 221 and a second conductive sheet 222 that are arranged opposite to each other, and a first connecting portion 223 connecting the first conductive sheet 221 and the second conductive sheet 222; Figure 12As shown, a placement groove 2111 matching the first connection portion 223 is provided on the connection piece 211; an opening 2112 is provided on one side of the placement groove 2111, and the opening 2112 penetrates to the edge of the connection piece 211, so that the first connection portion 223 can be placed in the placement groove 2111 through the opening 2112, and the first conductive sheet 221 is located on the first connection surface of the connection piece 211, and the second conductive sheet 222 is located on the second connection surface of the connection piece 211; wherein, the first connection surface and the second connection surface are two opposite connection surfaces of the connection piece 211; the first conductive sheet 221 is in direct contact with the battery 3 on the side where the first connection surface is located; the second conductive sheet 222 is in direct contact with the battery 3 on the side where the second connection surface is located.

[0110] It should be noted here that this embodiment is for the connection and conduction assembly 2 in the middle. When the connection and conduction assembly 2 is at both ends, there may be no battery on one side. At this time, the first conductive sheet 221 or the second conductive sheet 222 is not in contact with the battery.

[0111] Wherein, the inner wall of the placement groove 2111 is designed to be arc-shaped to prevent damage to the first connection portion 223 and the placement groove 2111 when the first connection portion 223 shakes in the placement groove 2111.

[0112] The opening 2112 can be perpendicular to the placement groove 2111, and the position of the opening 2112 can be on the side where the vertical distance from the placement groove 2111 to the edge of the connection piece 211 is greater than a preset distance, so that the depth of the opening 2112 reaches the preset distance. For example, in Figure 13 the depth W3 of the opening 2112 is greater than the preset distance. The preset distance is obtained by those skilled in the art through analysis of the structural characteristics of the battery conduction structure 22. After the first connection portion 223 is placed in the placement groove 2111, the first conductive sheet 221 can have a larger area located on the first connection surface, and the second conductive sheet 222 can have a larger area located on the second connection surface. On the one hand, it is to provide a sufficient contact surface for the battery 3, and on the other hand, it is to ensure the stability after the battery conduction structure 22 is installed on the connection piece 211. In actual use, the placement groove 2111 can be set at a position close to the edge of the connection piece 211, so that the other edge position of the connection piece 211 is far from the placement groove 2111, and thus the opening 2112 is provided on the side of the placement groove 2111 close to the other edge position.

[0113] The battery conduction structure 22 can be manifested as a U-shaped sheet that can be bent from the first connection portion 223, and the direction opposite to the first connection portion 223 is the opening; in another implementation manner, such as Figure 14As shown, the battery conductive structure 22 further includes a second connecting portion 224, that is, the two ends of the first conductive sheet 221 and the two ends of the second conductive sheet 222 are respectively connected, one end is connected by the first connecting portion 223, and the other end is connected by the second connecting portion 224, thereby forming a ring with a hollow groove. This implementation is more stable than the U-shaped sheet. Corresponding to this embodiment, the connecting sheet 211 is made of elastic material so that two springs are formed on both sides of the opening 2112, namely the first spring sheet 2113 and the second spring sheet 2114, as shown in FIG. Figure 13 As shown, when the battery conductive structure 22 needs to be installed on the connecting piece 211, the first elastic piece 2113 and the second elastic piece 2114 are respectively opened forward and backward, as shown in FIG. Figure 15 As shown, the hollow groove of the battery conductive structure 22 is then slid into the first elastic piece 2113 and the second elastic piece 2114, and the first connecting portion 223 is placed in the placement groove 2111. In this embodiment, in order to facilitate the installation of the battery conductive structure 22, this embodiment also provides a preferred embodiment, specifically: the width of the second elastic piece 2114 (i.e. Figure 13 d4 in (i.e., the distance between the opening 2112 and the first end of the placement slot 2111) is less than a first preset value, which is obtained by a person skilled in the art based on the elasticity of the connecting piece 211 and the structural characteristics of the battery conductive structure 22. The width of the second elastic piece 2114 is less than the first preset value to ensure that after the hollow slot of the battery conductive structure 22 slides into the first elastic piece 2113, the second elastic piece 2114 and the elasticity of the first elastic piece 2113 can enable the second elastic piece 2114 to slide into the hollow slot. In addition, the width of the second elastic piece 2114 can also be greater than the second preset value, which is also obtained by a person skilled in the art based on the elasticity of the connecting piece 211 and the structural characteristics of the battery conductive structure 22, thereby ensuring that the battery conductive structure 22 can be clamped by the second elastic piece 2114 without tilting or sliding after installation. Similarly, the width of the first elastic piece 2113 (i.e. Figure 13 d2 in ) and the width of the opening 2112 (ie Figure 13 The value d3) in the figure is also determined by those skilled in the art based on the elasticity of the connecting piece 211 and the structural characteristics of the battery conductive structure 22. In actual use, the connecting piece 211 and the fixing ring 212 can be made of plastic.

[0114] In actual use, the width of the placement slot 2111 (i.e. Figure 13The d1) therein is greater than a preset width, which is obtained by those skilled in the art through analyzing the structural characteristics of the battery conductive structure 22, so as to ensure that the first connection portion 223 of the battery conductive structure 22 can be smoothly installed into the placement groove 2111, and the first connection portion 223 does not have a large displacement in the placement groove 2111.

[0115] This embodiment also provides a preferred implementation manner. As Figure 14 shown, that is, the external conductive structure 23 is a connecting pipe; the connecting pipe is used for inserting an external line 4 therein to achieve connection with the external line 4.

[0116] The size of the connecting pipe can be obtained by those skilled in the art through analyzing and designing according to the size of the external line 4, or the connecting pipe can be provided with an opening. After the external line 4 is inserted into the connecting pipe, connection with the external line 4 is achieved by clamping the opening. The pipe orifice direction of the connecting pipe can be the direction of the series connection rod 1, so that after connecting the external line 4, the external line 4 extends from both ends or any one end of the series connection rod 1.

[0117] In an alternative implementation manner, as Figure 16 shown, a buckle 2122 is provided on the outer wall of the fixing ring 212; the connecting pipe is inserted into the buckle 2122 to achieve fixation of the connecting pipe.

[0118] Moreover, in order to ensure that after the first connection portion 223 is placed in the placement groove 2111, the connecting pipe can be inserted into the buckle 2122, as Figure 17 shown, the fixing ring 212 is provided with a notch 2123 at the position where the buckle 2122 is located, which is used to accommodate the extension portion 225 of the battery conductive structure 22. The extension portion 225 is the part where the battery conductive structure 22 extends until it is connected to the external conductive structure 23. As Figure 18 shown, and in order to avoid the notch 2123 affecting the stability of the fixing ring 212, the width of the extension portion 225 is relatively small. As Figure 19 shown, the width W5 of the extension portion 225 is less than the width W4 of the first conductive sheet 221 and the second conductive sheet 222. Correspondingly, the width of the main body of the battery conductive structure 22 (i.e., the first conductive sheet 221 and the second conductive sheet 222) gradually decreases at the connection part with the extension portion 225. For example, in Figure 19 it is shown that the width of the second connection portion 224 gradually decreases. The buckle 2122 can be a closed full-ring buckle or a partial-ring buckle with an opening.

[0119] In a preferred implementation manner, as Figure 17As shown, the inner wall of the buckle 2122 is provided with a first groove 21221 and a second groove 21222. The first groove 21221 and the second groove 21222 are oppositely arranged on both sides of the inner wall of the buckle (for example, respectively arranged on the left and right sides of the buckle, as shown in Figure 17), and the first groove 21221, the second groove 21222 and the other parts of the inner wall are smoothly and transitionally connected. The depths of the first groove 21221 and the second groove 21222 are obtained by those skilled in the art through requirement analysis. The first groove 21221 and the second groove 21222 facilitate the insertion of external lines on the one hand, and reduce the stress on both sides of the buckle on the other hand, thereby reducing the probability of the buckle breaking due to stress and prolonging the service life of the buckle. In actual use, the inner diameter r of the buckle is slightly smaller than the outer diameter R of the external line. If the depths of the first groove 21221 and the second groove 21222 are D, then r + 2D ≥ R, and usually r + 2D is slightly larger than R.

[0120] This embodiment also provides a preferred implementation manner, as Figure 20 shown, the protruding part 2121 includes a first sub-protruding part 21211 and a second sub-protruding part 21212; the duct 21210 includes a first sub-duct 212101 arranged on the first sub-protruding part 21211 and a second sub-duct 212102 arranged on the second sub-protruding part 21212; the first sub-protruding part 21211 and the second sub-protruding part 21212 are oppositely arranged, and the first sub-duct 212101 and the second sub-duct 212102 are oppositely arranged; a gap is arranged between the first sub-protruding part 21211 and the second sub-protruding part 21212 to form the slot 2120; as Figure 21 shown, the insertion piece 2110 is provided with a first through hole 21101 at a position aligned with the first sub-duct 212101 and the second sub-duct 212102, so that the series connection rod 1 passes through the first through hole 21101 when inserted into the duct 21210.

[0121] In an actual application scenario, the number of the insertion pieces 2110 is two, and a first through hole 21101 is arranged corresponding to each insertion piece 2110, so that the series connection rod 1, the connection piece 211 and the fixing ring 212 together form a stable structure, and the two insertion pieces 2110 are oppositely arranged. Due to possible errors in the device manufacturing process, and when the connection piece 211 is installed into the fixing ring 212, the fixing ring 212 needs to be opened, and there may also be a slight deformation in the elastic recovery of the fixing ring 212. Therefore, this embodiment also provides a preferred implementation manner, that is, the first through hole 21101 is an oval hole (that is, a hole with arcs at both ends), and the two ends of the oval hole are in the direction of the connection line of the two insertion pieces 2110 (that is Figure 21in the horizontal direction) so that when the insert piece 2110 is inserted into the slot 2120, even if there is an error between the connecting piece 211 and the fixing ring 212, it can ensure the alignment of the first through hole 21101 and the hole passage 21210 in the horizontal direction. And, the length of the slot 2120 is slightly greater than the width of the insert piece 2110 (i.e., Figure 13 W3 in

[0122] For example, the length of the slot 2120 can be the width of the insert piece 2110 plus a third preset value, which is obtained by those skilled in the art through empirical analysis. After the insert piece 2110 is inserted into the slot 2120, it can be aligned with the hole passage 21210 in the vertical direction by a small amount of up and down movement. Figure 22 In an actual application scenario, the radial length of the fixing ring 212 (i.e., the thickness of the fixing ring 212, i.e.,

[0123] d5 in Figure 23 is greater than a preset length, and the inner wall of the fixing ring 212 matches the side wall of the battery 3 to accommodate and hold the battery 3, and align the positive or negative electrode of the battery 3 with the corresponding battery conductive structure 22. The preset length is obtained by those skilled in the art through empirical analysis so that the inner wall of the fixing ring 212 can hold the battery 3. Figure 24 and Figure 25 In an alternative embodiment, as

[0124] shown, the number of the connecting rods 1 is two, namely a first connecting rod 11 and a second connecting rod 12; a locking assembly 5 is further included; as

[0125] In a preferred embodiment, in order to accommodate errors and deformations, both the second through hole 511 and the third through hole 512 are waist-shaped holes.

[0126] As Figure 26 and Figure 27 shown, the locking assembly 5 further includes a third screw 54 and a fourth screw 55. The third screw 54 and the fourth screw 55 are arranged inside the connecting conductive assemblies 2 at both ends of the series connection rod 1, that is, on the side close to the middle of the series connection rod 1, so that the third screw 54 and the first screw 52 clamp the connecting conductive assembly 2, and the fourth screw 55 and the second screw 53 clamp the connecting conductive assembly 2, thereby realizing the reinforcement of the structure. The connecting rod 51 is also designed with an abutting block 513. The abutting block 513 is arranged at a position opposite to the center of the connecting conductive assembly 2 (such as a position opposite to the battery conductive structure 22). Due to the existence of the fixing ring 212, when the locking assembly 5 is locked, the connecting rod 51 can only abut against the protrusion on the fixing ring 212 and cannot apply an abutting pressure to the center of the connecting conductive assembly 2. In order to further enhance the structural stability, the abutting block 513 is provided to make up for the gap between the connecting rod 51 and the center of the connecting conductive assembly 2, so as to abut and fix the center of the connecting conductive assembly 2. The thickness of the abutting block 513 is greater than or equal to the gap between the connecting rod 51 and the center of the connecting conductive assembly 2.

[0127] In some embodiments, the radial length of the protrusion 2121 (that is, the thickness of the protrusion 2121, that is Figure 22 d6 in Figure 22 ) is less than the radial length of the fixing ring 212 (that is d5 in

[0128] ). Figure 28 Figure 29 In actual use, as

[0129] shown, the structure of this embodiment further includes a housing 6. The housing 6 includes a cylindrical shell 61, a bottom cover 62 and a wiring cover 63; the cylindrical shell 61 surrounds the series connection rod 1, a plurality of connecting conductive assemblies 2 and the battery 3, the bottom cover 62 and the wiring cover 63 are respectively arranged at both ends of the cylindrical shell 61, and the two ends of the cylindrical shell 61 are provided with first threads, and the inner walls of the bottom cover 62 and the wiring cover 63 are provided with second threads matching the first threads to realize the screwing of the bottom cover 62 and the cylindrical shell 61, and the screwing of the wiring cover 63 and the cylindrical shell 61. Thread patterns are also provided on the outer walls of the wiring cover 63 and the bottom cover 62 to increase the friction when holding and tightening.

[0130] A wiring hole is correspondingly provided with a wiring cap 631 for closing the wiring hole when not in use, and a pressure relief hole is correspondingly provided with a pressure relief cap 632 for closing the pressure relief hole, as Figure 30 shown. It should be noted here that since the pressure relief hole is closed by the pressure relief cap 632 and the wiring hole is closed by the wiring cap 631, so in Figure 30 it is not shown, but it does not mean that the pressure relief hole and the wiring hole do not exist.

[0131] Moreover, it should be emphasized here that for the sake of clarity of the drawings, in this embodiment, for some drawings with many identical objects, one or several of them are often marked, and not all identical objects are marked. It can be understood that the quantity of such objects is not limited in this embodiment.

[0132] This embodiment also provides a battery string, as Figure 31 shown, which includes a plurality of batteries 3 and the battery string assembly structure described in Embodiment 1; the plurality of batteries 3 are arranged in the battery string assembly structure.

[0133] In an optional implementation manner, the external circuit 4 corresponding to each battery 3 is routed to one end of the battery string assembly structure and formed into a wire harness 7 by tying. In actual use, the wire harness 7 is located at the end where the wiring cover 63 is located, so as to facilitate wiring from the wiring hole of the wiring cover 63.

[0134] Among them, Figure 31 is a schematic diagram of the battery string after removing the outer shell 6, and the schematic diagram after adding the outer shell 6 is as Figure 28 shown.

[0135] Embodiment 2:

[0136] Before describing the solution of this embodiment, it is worth noting that the battery 3 proposed in Embodiment 1 is the single battery described in the following embodiments.

[0137] Based on Embodiment 1, in order to solve the problem that each single battery in the battery string is not fully charged and discharged in the prior art, in one embodiment, this embodiment provides a method for controlling the balanced charging and discharging of the battery string, which is implemented in the charging and discharging circuit of the battery string. Among them, a first switch is respectively arranged between the positive electrode of the charging and discharging module for controlling the charging and discharging of the battery string and the positive electrode of each single battery in the battery string, and a second switch is respectively arranged between the negative electrode of the charging and discharging module and the negative electrode of each single battery in the battery string, as Figure 32 shown, and the method includes:

[0138] Step 101: Obtain the sampled voltage across each single battery and the sampled current in the charging and discharging circuit of the battery string.

[0139] Among them, to obtain the sampled voltage across each single cell, sampling points need to be set at the positive and negative electrodes of each single cell. Since the battery string is formed by connecting multiple single cells in series, sampling points need to be set at the connection points between adjacent single cells, the positive electrode of the first single cell, and the negative electrode of the last single cell. By calculating the voltage difference between adjacent sampling points, the sampled voltage across each single cell can be obtained. The specific sampling method will be described below. In one embodiment, the current sampling point can be set in the charge and discharge circuit, such as using a current sensor to obtain the sampled current.

[0140] Step 102: Control the conduction states of the first switch and the second switch corresponding to the respective single cells according to the sampled voltage and the sampled current, so as to select to charge and discharge the single cells that meet the charge and discharge requirements respectively.

[0141] Among them, the single cells that meet the charge and discharge requirements refer to, after obtaining the state of charge of each single cell based on the sampled voltage and the sampled current, during the charging process, the fully charged single cells and the uncharged single cells are judged according to the corresponding state of charge, and by controlling the corresponding first switch and second switch, the uncharged single cells are selected to continue charging; during the discharging process, the fully discharged single cells and the not fully discharged single cells are judged according to the corresponding state of charge, and by controlling the corresponding first switch and second switch, the not fully discharged single cells are selected to continue discharging.

[0142] In the battery string, due to their own characteristics (such as internal resistance differences, initial charge differences, etc.), the voltages of different single cells may be different. In one embodiment, in order to determine whether a single cell needs to be charged or discharged, a charging threshold voltage V_ch and a discharging threshold voltage V_dis can be preset in advance. If the sampled voltage V_i of a certain single cell is lower than the charging threshold voltage V_ch (i.e., V_i < V_ch), it means that the state of charge of this single cell is low and it still needs to be charged; if the sampled voltage V_i of a certain single cell is higher than the discharging threshold voltage V_dis (i.e., V_i > V_dis), it means that the state of charge of this single cell is high and it needs to be discharged.

[0143] For the single cells that need to be charged, control the conduction of the corresponding first switch and second switch, so that the current output by the charge and discharge module can flow into this single cell and charge it.

[0144] For the single cells that need to be discharged, similarly control the conduction of the corresponding first switch and second switch. At this time, the charge and discharge module can control this single cell to discharge and release its excess charge.

[0145] In addition, when the entire battery string is in a charging state, if the sampled voltage of a certain single battery has reached the charging threshold voltage, even if the entire battery string is still charging, it is necessary to control the disconnection of the first switch and the second switch corresponding to this single battery to stop charging it and avoid overcharging. Similarly, when the entire battery string is in a discharging state, if the sampled voltage of a certain single battery has reached the discharging threshold voltage, it is also necessary to control the disconnection of its corresponding switch to prevent over-discharging.

[0146] In one embodiment, during the charging and discharging process, the voltage of the single battery will continuously change. Therefore, it is necessary to monitor the sampled voltage and the sampled current in real time and dynamically adjust the conduction states of the first switch and the second switch corresponding to each single battery. For example, when charging a certain single battery, as its charge increases, the sampled voltage will gradually rise. When the sampled voltage reaches the charging threshold voltage, promptly control the disconnection of the first switch and the second switch corresponding to this single battery to stop charging. On the contrary, during the discharging process, when the sampled voltage drops to the discharging threshold voltage, control the switch to disconnect to stop discharging.

[0147] In one embodiment, through the comprehensive control of the conduction states of the first switch and the second switch based on the sampled voltage and the sampled current, the charging and discharging of the single batteries in the battery string that meet the charging and discharging requirements are respectively achieved, thus solving the problem of incomplete charging and discharging of each single battery in the battery string and achieving the purpose of balanced charging and discharging of the battery string.

[0148] In one embodiment, as Figure 33 shown, the control of the conduction states of the first switch and the second switch corresponding to the respective single batteries according to the sampled voltage and the sampled current to selectively charge and discharge the single batteries that meet the charging and discharging requirements specifically includes:

[0149] Step 201: In the charging state, respectively determine whether the state of charge of each single battery is in a fully charged state or an uncharged state according to the sampled voltage and the sampled current.

[0150] During the charging process, the system continuously obtains the sampled voltage and the sampled current of each single battery. To determine whether the battery is fully charged, a clear standard is required. Generally, the battery manufacturer will give a reference value, which is usually related to the designed capacity of the battery. For common lithium-ion batteries, when its charge reaches 95%-100% of the designed capacity, it can be considered fully charged, but this standard is not absolute and is also affected by factors such as the battery usage time and temperature.

[0151] In one embodiment, after a certain single cell enters the constant voltage charging mode, the charging current is adjusted so that its voltage always remains at Va. As the single cell gradually becomes fully charged, the current used to maintain the single cell gradually decreases. When the corresponding sampling current decreases to Ia, it means that the single cell is fully charged; otherwise, it is not fully charged. Among them, when the battery charging reaches the highest charging voltage (the current highest charging voltage of the battery in use is 3.65V), this single cell enters the constant voltage charging mode. The constant voltage charging mode is controlled by controlling the charging current. In one embodiment, as Figure 34 shown, when the temperature is 10°C and the battery charge of the single cell is between 0 and 80%, the maximum charging current is 0.5C. For example, if the current capacity of the single cell in use is 50AH, a charging current of 0.5C represents 50AH * 0.5C = 25A, that is: the current single cell can currently be charged with a maximum current of 25A. By analogy, the maximum charging current of each battery can be obtained.

[0152] When the maximum charging current is determined according to the above method and used for charging, if it is obtained that the voltage of a certain single cell exceeds 3.65V, the charging current is reduced. At the same time, the sampling voltage of this single cell will also decrease as the charging current decreases. If it is found that the sampling voltage of the single cell that has reached 3.65V drops below 3.65V due to the reduction of the charging current, the charging current is increased to keep it at 3.65V. During the process of dynamically adjusting the current, the maximum charging current does not exceed the maximum charging current determined above. The time granularity of sampling and control in the constant voltage stage is 1 second (which can be dynamically configured), and the step value of the increase or decrease of the charging current each time is 0.1A. Through the above process, the system can also evaluate the maximum charging current of each single cell separately and select the minimum value as the charging current for charging, which can not only ensure that the single cell is not damaged but also ensure the charging speed as much as possible.

[0153] In one embodiment, the system will judge the state of charge of the battery based on the sampling voltage and sampling current and in combination with the characteristics of the battery to determine whether the single cell is fully charged. For example, if the sampling voltage of a single cell continues to rise and the current gradually decreases, this may mean that the battery is approaching the fully charged state. When the voltage reaches a preset upper limit value and the current drops to a very small value at the same time, it can be judged that this battery is fully charged. On the contrary, if the voltage is still relatively low and the current is relatively large, then this battery is in the not fully charged state.

[0154] Step 202: Disconnect the first switch and the second switch at both ends of the first monomer battery that is in a fully charged state, conduct the first switch and the second switch at both ends of the second monomer battery that is in an uncharged state, and control the charge and discharge module to charge the second monomer battery until it is detected that the state of charge of the second monomer battery reaches the fully charged state.

[0155] Alternatively, obtain the connection relationship of the second monomer batteries that are in an uncharged state. If there are at least two second monomer batteries forming a series relationship, form a series battery pack with at least two second monomer batteries, and conduct the first switch corresponding to the series battery pack and the second switch corresponding to the series battery pack.

[0156] Among them, overcharging will damage the monomer battery and shorten the service life of the monomer battery. For the first monomer battery determined to be in a fully charged state, the system will immediately issue an instruction to control the disconnection of the first switch and the second switch at both ends of it. After disconnecting the corresponding switch, the charge and discharge module can no longer deliver current to the first monomer battery, avoiding the occurrence of overcharging. In one embodiment, during the charging process, when it is determined that multiple monomer batteries are fully charged, the corresponding first switch and second switch of each of them are disconnected respectively.

[0157] For the second monomer battery that is in an uncharged state, since there are fully charged monomer batteries in the battery string, the original charging circuit is no longer conductive. Therefore, the system will control the conduction of the first switch and the second switch at both ends of it. After conducting the corresponding switch, the charge and discharge module and these uncharged batteries form a complete charging circuit, and the current can flow from the charge and discharge module to one or more second monomer batteries to start charging the second monomer battery continuously. During the continuous charging process of one or more second monomer batteries, the system will continuously monitor the voltage and current changes of each second monomer battery. As the charging progresses, the sampled voltage of the second monomer battery will gradually increase, and the corresponding sampled current will gradually decrease. When the system detects that the standard of the fully charged state is reached, it will immediately issue an instruction to control the disconnection of the first switch and the second switch at both ends of the corresponding second monomer battery, or directly turn off the charge and discharge module to stop charging, so as to ensure that each battery can be charged to an appropriate amount of electricity, neither undercharged nor overcharged.

[0158] During the charging process, the system will also dynamically adjust the charging current according to the state of the monomer battery. At the initial stage of charging, the battery has a low power level. At this time, a relatively large charging current (i.e., the minimum value of the maximum charging current corresponding to each monomer battery) can be used for rapid charging. As the power level of the monomer battery increases, the charging current will gradually decrease to prevent the battery from overheating and overcharging. When it is detected that the monomer battery is approaching the fully charged state, a smaller current will be used for trickle charging, which can ensure the safety and stability of battery charging and thus extend the service life of the battery.

[0159] In one embodiment, as Figure 35 shown, controlling the conduction states of the first switch and the second switch corresponding to the respective single cells according to the sampled voltage and the sampled current respectively to selectively charge and discharge the single cells that meet the charge and discharge requirements further includes:

[0160] Step 301: In the discharge state, determine whether the state of charge of each single cell is in a fully discharged state or an incompletely discharged state according to the sampled voltage and the sampled current respectively.

[0161] Among them, when the battery string is in the discharge state, the system continuously obtains the sampled voltage and sampled current information of each single cell, which are real-time changing and reflect the current discharge state of the single cell. For different types of batteries, there are different criteria for defining the fully discharged state. Generally speaking, it is based on factors such as the rated voltage, design capacity, and safe operating range of the battery. For example, for common lithium-ion batteries, when the voltage of a single cell drops to a specific lower limit value (such as 2.5V - 3.0V), the battery is usually considered to be in a fully discharged state. Because if over-discharged continuously, it will cause irreversible damage to the internal structure of the battery, reducing the performance and lifespan of the battery.

[0162] If the sampled voltage of a certain single cell has dropped to the above-mentioned lower limit value, or it is found through combined current analysis that the single cell can no longer provide effective electrical energy output, then it is determined that the single cell is in a fully discharged state. On the contrary, if the sampled voltage is still higher than the lower limit value and the current is still flowing within the normal range, it means that the single cell still has remaining charge and is in an incompletely discharged state.

[0163] Step 302: Disconnect the first switch and the second switch at both ends of the third single cell in the fully discharged state, conduct the first switch and the second switch at both ends of the fourth single cell in the incompletely discharged state, and control the charge and discharge module to discharge the fourth single cell until it is detected that the state of charge of the fourth single cell reaches the fully discharged state.

[0164] Or, obtain the connection relationship of the second single cells in the incompletely discharged state. If there are at least two second single cells forming a series relationship, form a series battery pack with at least two second single cells, and conduct the first switch corresponding to the series battery pack and the second switch corresponding to the series battery pack.

[0165] In one embodiment, when it is determined that a certain third single cell is in the fully discharged state, the system quickly issues a control signal to disconnect the first switch and the second switch at both ends of the third single cell, preventing current from continuing to flow out of the corresponding third single cell and avoiding over-discharge.

[0166] For the fourth single cell in an incompletely discharged state, the system will control the corresponding first switch and second switch to conduct. In this way, a closed discharge loop is formed between the charge-discharge module and the corresponding one or more fourth single cells, and the electrical energy in the corresponding fourth single cell can be output through the charge-discharge module to supply power to external devices. During this process, the charge-discharge module will reasonably adjust the magnitude of the discharge current according to the requirements of external devices.

[0167] It should be noted that during the discharge process of the fourth single cell, the system will continuously monitor the changes in its sampled voltage and sampled current. As the discharge progresses, the sampled voltage will gradually decrease, and the sampled current will also change according to the changes in the external load. When the system detects that the sampled voltage of the corresponding fourth single cell drops to the standard value of full discharge, or determines that the battery can no longer effectively discharge according to the current change, it will control the first switch and second switch at both ends of the fourth single cell to disconnect and stop the discharge. This ensures that each single cell can discharge within a safe range and avoids damage to the battery caused by over-discharge.

[0168] In summary, during the entire discharge process, the system will uniformly manage all single cells, pay real-time attention to the state changes of each single cell, and dynamically adjust the on and off states of the corresponding first switch and second switch to ensure that the battery string can stably and efficiently supply power to external devices. At the same time, in this way, the discharge degree of each single cell can be made as uniform as possible, improving the overall performance and service life of the battery string.

[0169] The state of charge of a single cell has a significant impact on its maximum discharge current. When the single cell is in a relatively high state of charge, it can generally withstand a relatively large discharge current. When the state of charge is low, the internal resistance of the battery increases. If it discharges at a large current at this time, too much heat will be generated, which may damage the battery. For example, when the SOC (full English name: State of Charge) of a single cell is 80%, it can safely discharge at a current of 3C. However, when the SOC drops to 20%, the maximum safe discharge current may need to be reduced to 1C. Secondly, temperature is also an important factor affecting the maximum discharge current of the battery. In a low-temperature environment, the chemical reaction rate inside the single cell slows down, and the ion conduction ability decreases. At this time, the maximum discharge current of the single cell will be limited. For example, in an environment of -20°C, the original maximum discharge current of a certain single cell of 3C may need to be reduced to 1C or even lower to prevent problems such as lithium plating inside the battery, which will affect the battery performance and safety. As the number of battery usage increases, the electrode materials inside the battery will gradually age, the internal resistance increases, and its maximum discharge current will also decrease accordingly. For example, the maximum discharge current of a new battery is 5A. After 500 charge and discharge cycles, due to the aging of the electrode materials, the maximum discharge current may drop to 3A. During the discharge process of the battery string, the method for controlling the balanced charge and discharge of the battery string further includes: evaluating the maximum discharge current that each single cell can accept during the discharge process of the battery string, and controlling the charge and discharge module to perform series discharge according to the minimum value among the maximum discharge currents.

[0170] In one embodiment, as Figure 36 shown, when each single cell leaves the factory, the manufacturer will provide a detailed specification sheet, which will clearly mark the maximum discharge current that the battery can withstand. In one embodiment, sensors in the battery management system can be used to monitor parameters such as the voltage, current, and temperature of the single cell in real time, and combined with a preset algorithm to dynamically evaluate the maximum discharge current of each single cell. For example, by monitoring the voltage change rate of the battery under different working conditions and combining the equivalent circuit model of the battery, the maximum discharge current that the battery can withstand in the current state can be deduced.

[0171] After evaluating the maximum discharge current of each single cell, select the minimum value from the maximum discharge current values of all single cells. For example, referring to Figure 36 , the maximum discharge current of single cell A is 50AH * 0.5C = 25A, and the maximum discharge current of single cell B is 50AH * 1C = 50A. Then the discharge current finally determined for the series circuit of A and B is set to min(25, 50) = 25A.

[0172] As the discharge progresses, parameters such as the state of charge and temperature of each single battery will change continuously, and the maximum discharge current of each single battery may also change. For example, during the discharge process, if the temperature of a single battery rises, its maximum discharge current may decrease. At this time, it is necessary to re-evaluate the maximum discharge current of each single battery, determine the new minimum value, and correspondingly adjust the discharge current of the charge-discharge module to ensure that the entire battery string always operates under safe conditions.

[0173] In one embodiment, in a photovoltaic system, the photovoltaic module converts light energy into electrical energy and stores it in the corresponding battery string (i.e., the charge-discharge module charges the battery string in this embodiment). When there is insufficient light energy on a cloudy day or no light at night, and the electrical energy transmitted by the photovoltaic module cannot fully charge each single battery in the battery string, the method for controlling the balanced charge and discharge of the battery string further includes: when the charge-discharge module can only support charging the remaining single battery, select the single battery with the lowest voltage for charging according to a preset period, so as to continuously increase the power of the single battery with the lowest voltage and reduce the voltage difference between each single battery.

[0174] Taking the photovoltaic system as an example, the photovoltaic module converts light energy into electrical energy during the day and charges the battery string. However, on a cloudy day with low light intensity or at night without light, the electrical energy generated by the photovoltaic module decreases significantly, making it difficult to fully charge each single battery in the battery string. At this time, the system will monitor the output power of the charge-discharge module and the charging requirements of the battery string in real time. When it is found that the power output by the charge-discharge module is only enough to charge the remaining single battery, the subsequent balanced charging strategy will be triggered. For example, a photovoltaic system is equipped with a charge-discharge module with a rated power of 100W. On a cloudy day, the output power of the photovoltaic module drops to 20W, and there are multiple uncharged single batteries in the battery string. If the power required to fully charge each single battery exceeds 20W, it is determined that the charge-discharge module can only support charging a single battery.

[0175] In order to reduce the voltage difference between each single battery, the system will periodically screen out the single battery with the lowest voltage based on the voltage data of each single battery collected. The preset period can be set according to the actual situation, for example, screening is performed every 30 minutes. Each time screening is performed, the system will traverse the voltage values of all uncharged single batteries and find the single battery with the lowest voltage through comparison. For example, there are 5 uncharged single batteries in the battery string, and their voltages are 3.2V, 3.3V, 3.1V, 3.4V, and 3.25V respectively. After comparison, the single battery with a voltage of 3.1V will be selected.

[0176] After determining the single cell with the lowest voltage, the system will control the first switch and the second switch corresponding to this single cell, so that the charge-discharge module only charges this single cell. During the charging process, the system will continuously monitor the voltage change of this single cell. When the charging reaches a certain duration, or the voltage of the single cell rises to the set threshold, the charging will be paused. Then, entering the next preset cycle, the system will again select the single cell with the lowest voltage for charging. For example, if the initial voltage of the selected single cell is 3.1V and the charging threshold is set to 3.5V, when the voltage of this single cell reaches 3.5V, the charging will be paused. In the next 30-minute cycle, the system will again select the single cell with the lowest voltage. Maybe at this time, the voltage of another single cell is the lowest, and then it will be charged.

[0177] By continuously selecting the single cell with the lowest voltage for charging according to the preset cycle, the charge of this single cell will be increased each time during charging, thereby increasing its voltage. As time goes by, the voltage difference between each single cell will gradually decrease, improving the overall performance of the battery string.

[0178] In a series-connected battery string, if the voltages of some single cells are too high and the voltages of some single cells are too low, the performance of each single cell will be inconsistent, thus affecting the use of the entire battery string. When the charge-discharge module completely stops generating electrical energy, that is, corresponding to the above example, the photovoltaic module fails and cannot continue to charge the battery string. In order to ensure that the voltage difference between each single cell is minimized and the stability of the battery string is maintained when the photovoltaic module fails, in one embodiment, an energy storage module is provided between the positive electrode of each first switch and the corresponding single cell, and each energy storage module is equipped with a corresponding control switch, and the energy storage module includes an energy storage unit.

[0179] As Figure 37 shown, the method for controlling the balanced charge and discharge of the battery string further includes:

[0180] Step 401: When the charge-discharge module cannot support charging the remaining single cells that are still not fully charged, turn off the charge-discharge module, and respectively obtain the state of charge of each single cell according to the sampled voltage and the sampled current.

[0181] During the charging process, the system will monitor the output capacity of the charge and discharge module in real time. When the charge and discharge module is unable to continue providing sufficient charging current for the remaining uncharged single cells due to its own power limitation, failure, insufficient power, etc., the system will make a judgment and turn off the charge and discharge module. For example, a charge and discharge module with a designed power of 100W, after long-term operation, due to reasons such as internal component heating, its actual output power drops to only 30W, while the remaining uncharged single cells require 50W of power to charge normally. In this case, it is determined that the charge and discharge module cannot support charging and it is turned off.

[0182] After turning off the charge and discharge module, the system will calculate the state of charge of each single cell based on the sampled current collected. Specifically, the state of charge of each single cell at each moment is calculated through the following formula:

[0183]

[0184] where Q is the integral value (i.e., the charge charged into the single cell from the start of charging to the current moment), t a is the start time of charging, t b is the current moment, and I(t) is the sampled current. It should be noted that in order to accurately obtain the state of charge of each single cell at each moment, it is necessary to ensure that the state of charge of each single cell is 0 (i.e., in a fully discharged state) at the start of charging.

[0185] Step 402: Compare the state of charge between adjacent single cells, and by controlling the conduction states of the first switch, the second switch, and the control switches of the corresponding energy storage modules, enable the single cell with a larger state of charge to charge the corresponding energy storage unit.

[0186] Among them, after obtaining the state of charge of each single cell, the system will compare the state of charge of adjacent single cells one by one. For example, in a battery string composed of 10 single cells connected in series, the state of charge of the 1st and 2nd single cells, the 2nd and 3rd single cells... and the 9th and 10th single cells will be compared.

[0187] When it is found that among two adjacent single cells, the state of charge of one single cell (with a larger state of charge) is significantly higher than that of the other (with a smaller state of charge), the system will control the corresponding switch to conduct. Specifically, Figure 38As shown, through the above detection process, at a certain detection node, the state of charge of the single cell A is greater than that of the single cell B. Therefore, the first switch Sa1 corresponding to the single cell A, the first switch Sb1 corresponding to the single cell B, the control switch Ka2, and the control switch Kb1 of the corresponding energy storage unit LB are turned on, and the second switch Sa2 of the single cell A is turned off, so that the single cell A and the corresponding energy storage unit LB form a charging circuit, thereby enabling the single cell A to charge the energy storage unit LB.

[0188] Step 403: After charging the energy storage unit for a preset time, by controlling the conduction states of the first switch, the second switch, and the control switches of the corresponding energy storage units, the charged energy storage unit is used to charge the single cell with a smaller state of charge.

[0189] Still taking the above example, the system will preset a charging time for the single cell A to charge the energy storage unit LB. The preset time can be determined comprehensively according to factors such as the capacity of the energy storage unit, the remaining power of the single cell with a larger state of charge, and the charging current.

[0190] In one embodiment, referring to Figure 38 , when the single cell A charges the energy storage unit LB to the preset time, the system will re-control the conduction states of the switches. At this time, the first switch Sa1 is turned off, the second switch Sb2 corresponding to the single cell B is turned off, the first switch Sb1 corresponding to the single cell B, the first switch Sc1 corresponding to the single cell C, and the control switch Kc2 on the energy storage unit LC are turned on, so that the charged energy storage unit LB and the single cell B form a charging circuit, thereby enabling the energy storage unit LB to charge the single cell B.

[0191] Through the above steps, when the charge and discharge module cannot support charging, the energy storage module is used to achieve the state of charge balance between adjacent single cells, improving the overall performance and service life of the battery string.

[0192] In summary, in this embodiment, by obtaining the sampled voltage across each single cell and the sampled current in the charge and discharge circuit of the battery string; then respectively controlling the conduction states of the first switch and the second switch corresponding to the respective single cells according to the sampled voltage and the sampled current to select to charge and discharge the single cells that meet the charge and discharge requirements respectively; it is possible to charge and discharge each single cell individually, and finally achieve the full charge and full discharge of each single cell; solving the limitation that only one or a very small number of single cells can be fully utilized in the energy storage battery system; it is possible to charge and discharge a single cell or multiple single cells together; solving the problem of unbalanced charge and discharge of the battery system, thereby maximizing the utilization of battery resources.

[0193] Embodiment 3:

[0194] Based on Embodiment 1 and Embodiment 2, for the battery string assembly structure proposed in Embodiment 1, during the actual installation of the battery string, it may lead to poor contact between single cells, resulting in too large contact resistance between single cells, wasting charge and discharge energy, and affecting the evaluation of the power of single cells in Embodiment 2. As a result, a single cell may be determined to be full when it is far from being full, and determined to be discharged when it is far from being fully discharged. There are various links from production to successful installation, and accidental bumps may cause poor contact. Even after successful installation with good contact resistance, it cannot be guaranteed that the contact resistance will not increase after subsequent wind and rain. Therefore, in order to prevent the contact resistance from affecting the feasibility of the method for controlling the balanced charge and discharge of the battery string proposed in this embodiment (that is, the contact resistance affects the sampled voltage, and the influence on the sampled voltage directly affects the judgment of the state of charge of a certain single cell), to solve the above problems, in one embodiment, as Figure 39 shown, the method for controlling the balanced charge and discharge of the battery string further includes: before the charge and discharge process of the battery string, detecting the contact resistance of each single cell in the battery string, specifically including:

[0195] Step 501: Obtain the open-circuit voltage of each single cell in the battery string in the open-circuit state.

[0196] Among them, before performing the charge and discharge operation on the battery string, the system first sets the battery string to the open-circuit state, that is, disconnects all connections with external loads and charge and discharge devices. Using a high-precision voltage sensor, collect the open-circuit voltage at both ends of the positive and negative electrodes of each single cell. The open-circuit voltage can reflect the potential difference of the single cell when there is no current passing through. Taking a battery string composed of three single cells connected in series as an example, use a professional voltage measuring device to measure the open-circuit voltage of each single cell one by one and record the data. For example, the open-circuit voltages of the three single cells are V_10 = 3.2V, V_20 = 3.18V, and V_30 = 3.22V in sequence.

[0197] Step 502: Output a short-term constant current through a constant current source to charge the battery string, and obtain the sampled voltage at both ends of each single cell during the charging process.

[0198] A constant current source is used to output a specific short - time constant current to the battery string. The magnitude and duration of the short - time constant current need to be determined according to the specifications and characteristics of the battery string. The purpose is to let the current pass through the battery string to generate a voltage drop caused by the contact resistance for each single battery, while not overcharging the single battery or causing other damages. During the constant - current charging process, the system collects the real - time voltage across each single battery as the collected voltage. Still taking the battery string composed of the above three single batteries as an example, assume that the current I output by the constant - current source is 1 A and the duration is 0.5 s. Within this 0.5 s, the system measures the collected voltage across each single battery through a voltage sensor, which are V_1 = 3.25 V, V_2 = 3.23 V, and V_3 = 3.27 V respectively.

[0199] Step 503: Obtain the contact resistance of the corresponding single battery according to the open - circuit voltage, the short - time constant current, and the collected voltage.

[0200] According to Ohm's law R = △V / I, △V is the voltage change of the single battery during constant - current charging, that is, the difference between the collected voltage and the open - circuit voltage, and I is the short - time constant current output by the constant - current source.

[0201] Taking the first single battery as an example, the calculation process of its contact resistance Rc1 is as follows:

[0202] △V = V_1 - V_10 = 3.25 V - 3.2 V = 0.05 V. According to Ohm's law, Rc1 = △V / I = 0.05 V / 1 A = 0.05 Ω; similarly, the contact resistances of other single batteries can be calculated.

[0203] Through the above steps, the system can detect the contact resistance of each single battery before charging and discharging the battery string. Once it is found that the contact resistance of a certain single battery exceeds the normal range, measures can be taken in time, such as re - checking the connection, replacing the connecting parts, etc., to ensure the feasibility of the method for controlling the balanced charging and discharging of the battery string proposed in Embodiment 1, and to avoid affecting the performance evaluation and charging and discharging effect of the single battery due to contact resistance problems.

[0204] In one embodiment, after obtaining the contact resistance of each single battery in the above - mentioned manner, the obtaining of the sampling voltage across each single battery specifically includes: during the charging process, the calculation formula of the sampling voltage is: Vc = Vm - Ic*Rc; during the discharging process, the calculation formula of the sampling voltage is: Vc = Vm + Ic*Rc; where Vc is the sampling voltage, Vm is the voltage value actually collected across each single battery, Ic is the sampling current, and Rc is the contact resistance corresponding to the corresponding single battery.

[0205] During the actual charge and discharge process of the battery string, the existence of contact resistance will affect the measurement of the voltage across the individual battery. To obtain a more accurate sampled voltage, it is necessary to correct the actually collected voltage value based on the detected contact resistance. The calculation method of the sampled voltage will be introduced separately from the charging and discharging processes below.

[0206] During charging, the current flows into the battery string from the charging source, and the contact resistance will cause a voltage loss. At this time, for example, when charging the battery string composed of the three individual batteries mentioned above, the actually collected voltage value Vm1 across the first individual battery is 3.5V, the sampling current Ic = 0.8A. Through previous detection, the contact resistance Rc1 of the first individual battery is known to be 0.05Ω. Substitute the above data into the formula: Vc = 3.5V - 0.8A * 0.05Ω = 3.46V, indicating that considering the 0.04V voltage loss caused by the contact resistance, the true sampled voltage of the first individual battery is 3.46V. For other individual batteries, use the same method and substitute their corresponding Vm, Ic, and Rc values to calculate the accurate sampled voltage.

[0207] During discharging, the current flows out of the battery string, and the contact resistance will also affect the sampled voltage. However, contrary to the charging process, the contact resistance will cause the voltage to increase at this time. Therefore, the formula for calculating the sampled voltage is Vc = Vm + Ic * Rc. Still taking the battery string composed of the above three individual batteries as an example: the actually collected voltage value Vm2 across the second individual battery is 3.0V, the sampling current Ic = 0.6A, and the contact resistance R_c2 of the second individual battery is 0.05Ω. Substitute the above data into the formula: Vc = 3.0V + 0.6A * 0.05Ω = 3.03V, which indicates that considering the contact resistance increases the voltage by 0.03V, the true sampled voltage of the second individual battery is 3.03V. By analogy, perform similar calculations on the remaining individual batteries to obtain the accurate sampled voltage.

[0208] By calculating the sampled voltage according to the above formula during the charging and discharging processes, the influence of the contact resistance on the voltage measurement can be effectively compensated, and a sampled voltage that can better reflect the true state of the individual battery can be obtained. This not only improves the accuracy of the battery state of charge judgment but also provides reliable data support for the implementation of the battery string balanced charge and discharge control strategy, further ensuring the stable operation and service life of the battery system.

[0209] Example 4:

[0210] To further illustrate the foregoing embodiments, this embodiment proposes a circuit for controlling the balanced charge and discharge of the battery string, as Figure 40As shown in the figure, it includes: a control module, a charge and discharge module, a voltage sampling module, a current sampling module, and a switch module. The positive electrode of the charge and discharge module is connected to the positive electrode of the battery string, and the negative electrode of the charge and discharge module is connected to the negative electrode of the battery string; the switch module includes a first switch disposed between the positive electrode of each single battery and the positive electrode of the charge and discharge module, and a second switch disposed between the negative electrode of each single switch and the negative electrode of the charge and discharge module; the sampling points of the voltage sampling module are respectively connected to the positive and negative electrodes of each single battery; the current acquisition module is connected in series in the main circuit of the charge and discharge module; the control module is respectively connected to the charge and discharge module, the voltage sampling module, the current sampling module, and the control ends of the respective switches in the switch module.

[0211] The charge and discharge module is used to charge or discharge the battery string according to the instruction of the control module; the voltage sampling module is used to respectively obtain the sampling voltages at both ends of each single battery, and the current sampling module is used to obtain the sampling current in the main charge and discharge circuit of the battery string; the control module is used to respectively control the on-off states of the first switch and the second switch corresponding to the respective single batteries according to the sampling voltage and the sampling current, so as to select to charge and discharge the single batteries that meet the charge and discharge requirements respectively, so as to achieve the charge and discharge balance of each single battery in the battery string in the charge and discharge state.

[0212] Among them, the entire circuit is built with the goal of controlling the battery string to achieve balanced charge and discharge, and includes a control module, a charge and discharge module, a voltage sampling module, a current sampling module, and a switch module. The positive electrode of the charge and discharge module is connected to the positive electrode of the battery string, and the negative electrode is connected to the negative electrode of the battery string, and is responsible for delivering charging current to the battery string or guiding the battery string to discharge. The first switches in the switch module are distributed between the positive electrode of each single battery and the positive electrode of the charge and discharge module, and the second switches are distributed between the negative electrode of each single battery and the negative electrode of the charge and discharge module. By controlling the on-off of the corresponding first switch and second switch, it is determined whether the single battery is connected to the charge and discharge circuit to charge or discharge. In one embodiment, both the first switch and the second switch can be MOS (Metal-Oxide-Semiconductor Field-Effect Transistor) tubes controlled by the control module to output corresponding Pulse Width Modulation (PWM) signals (such as PWM1 to PWM8).

[0213] The voltage sampling module is used to obtain the voltage information at both ends of the single battery in real time. The current sampling module is connected in series in the main circuit of the charge and discharge module and is used to monitor the magnitude of the current during the charge and discharge process. The control module is used to collect and analyze the information fed back by each module, and then issue instructions for the operation of the entire circuit.

[0214] For the charge and discharge module, when the control module issues a charging instruction, the charge and discharge module obtains electrical energy from an external power source and delivers it to the battery string to charge the battery; when the control module issues a discharging instruction, the charge and discharge module guides the battery string to release electrical energy to supply power to an external load. For example, in a photovoltaic energy storage system, during the day, the photovoltaic panel generates electrical energy, and the control module will instruct the charge and discharge module to store the electrical energy in the battery string; when electricity is needed at night, the control module commands the charge and discharge module to discharge the battery string to provide power for household electrical appliances.

[0215] During the charging stage, the control module comprehensively analyzes the sampled voltages of each single battery. For single batteries with relatively low sampled voltages and insufficient state of charge, the control module controls the corresponding first switch and second switch to conduct, allowing the charge and discharge module to charge them. As the charging progresses, the voltage sampling module continuously monitors the voltage changes of the single batteries. When the voltage of a certain single battery reaches the preset full charge threshold, the control module will control the corresponding first switch and second switch to disconnect and stop charging the single battery.

[0216] In one embodiment, as Figure 41 shown, taking four single batteries as an example, when it is detected that single battery 1 is fully charged and single batteries 2, 3, and 4 are not fully charged (the specific detection method refers to Embodiment 1 and will not be elaborated here), disconnect switch Q1 (i.e., the first switch corresponding to single battery 1) and switch Q5 (i.e., the second switch corresponding to single battery 1), and conduct switch Q2 (i.e., the first switch corresponding to single battery 2) and switch Q8 (i.e., the second switch corresponding to single battery 4), then it is possible to continue charging the sub-battery string composed of single batteries 2, 3, and 4.

[0217] In one embodiment, as Figure 42 shown, also taking four single batteries as an example, when it is detected that single batteries 2 and 3 are fully charged and single batteries 1 and 4 are not fully charged, disconnect switch Q2 (i.e., the first switch corresponding to single battery 2), switch Q6 (i.e., the second switch corresponding to single battery 2), switch Q3 (i.e., the first switch corresponding to single battery 3), and switch Q7 (i.e., the second switch corresponding to single battery 3), and conduct switch Q1, switch Q5, switch Q4 (i.e., the first switch corresponding to single battery 4), and switch Q8 (i.e., the second switch corresponding to single battery 4). Among them, when charging the entire battery string, switch Q1 and switch Q8 need to be conducted. Therefore, in the above process, just check whether switch Q1 and switch Q8 are in the conducting or off state, and there is no need to repeat the control.

[0218] In one embodiment, referring to Figure 41 and Figure 42, after only detecting that the single cell 1 is fully charged (or discharged), the sub-battery string composed of the single cell 2, the single cell 3, and the single cell 4 needs to continue charging (or discharging). At this time, only the first switch between the positive electrode of the sub-battery string and the positive electrode of the charge and discharge module, and the second switch between the negative electrode of the sub-battery string and the negative electrode of the charge and discharge module need to be turned on to achieve the charging or discharging of the sub-battery string.

[0219] The conduction conditions of each switch in other charge and discharge cases can be obtained according to the above principles and the attached drawings, and will not be elaborated in this embodiment.

[0220] In one embodiment, the discharge stage is the same as the charging stage. The control module will pay attention to the single cell with a higher state of charge, control the conduction of its corresponding switch, and give priority to discharging. At the same time, the discharge current is monitored through the current sampling module to ensure the safety and stability of the discharge process. As the discharge continues, when the state of charge of the single cell drops to a certain level, the control module will control the corresponding first switch and second switch to disconnect to prevent over-discharge.

[0221] Through the above method, throughout the entire process of charge and discharge, it is ensured that each single cell can be charged and discharged at an appropriate time, realizing the balanced charge and discharge of the battery string, effectively extending the service life of the battery string, and improving the overall performance of the battery system.

[0222] Referring to the foregoing embodiment, in a series-connected battery string, if some single cells have too high a voltage and some single cells have too low a voltage, the performance of each single cell will be inconsistent, thus affecting the use of the entire battery string. When the charge and discharge module completely stops generating electrical energy, in a photovoltaic system, if a photovoltaic module fails or does not generate electricity and cannot continue to charge the battery string, in order to ensure that the voltage difference between each single cell is minimized when the photovoltaic module fails to maintain the stability of the battery string, in one embodiment, as Figure 43 shown, the circuit for controlling the balanced charge and discharge of the battery string further includes an energy storage module arranged in each charge and discharge loop where a single cell is located. The energy storage module includes an energy storage unit, a first control switch, and a second control switch; one ends of the first control switch and the second control switch are respectively connected to one end of the first switch, the other end of the first control switch is connected to one end of the energy storage unit, and the other end of the energy storage unit and the other end of the second control switch are respectively connected to the positive electrode of each single cell. It should be noted that an energy storage module can be arranged or not arranged between the positive electrode of the first single cell and the last single cell and its corresponding first switch. The energy storage unit can be an inductor or a capacitor. In this embodiment, an inductor is taken as an example. The first control switch and the second control switch are both MOS transistors controlled by the control module to output PWM signals.

[0223] Among them, when the charge-discharge module fails or stops generating electricity, by detecting the state of charge of each battery (specific detection methods refer to the foregoing embodiments), the state of charge of two adjacent single cells is judged, and the single cell with a larger state of charge charges the single cell with a lower state of charge to balance the electricity between the single cells and maintain the stability of the battery system.

[0224] In one embodiment, as Figure 44 shown, when it is detected that the state of charge of single cell 1 is greater than that of single cell 2, switch Q1, switch Q2 and control switch K1 are turned on to form a charging circuit including energy storage unit L1, control switch K1, switch Q2, switch Q1 and single cell 1, so as to charge energy storage unit L1 through single cell 1.

[0225] In one embodiment, as Figure 45 shown, after charging energy storage unit L1 for a preset time, switch Q1 is turned off, and switch Q3 and control switch K22 are turned on to form a charging circuit including energy storage unit L1, control switch K1, switch Q2, switch Q3, control switch K22 and single cell 2, so as to charge single cell 2 through energy storage unit L1, thereby realizing the transfer of part of the electricity in single cell 1 to single cell 2. When the charge-discharge module cannot support charging, the energy storage unit L1 is used to realize the electricity balance between adjacent single cells 1 and 2, improving the overall performance and service life of the battery string.

[0226] Similarly, in other embodiments, the electricity in multiple single cells can be transferred to one single cell. Specifically, the control of each switch is referred to the above method to obtain the corresponding charging circuit, which will not be elaborated in this embodiment.

[0227] In the entire battery system, temperature and humidity will affect the stability of the battery string. Therefore, it is usually necessary to detect the temperature and humidity of the entire battery system. The circuit for controlling the balanced charge and discharge of the battery string further includes a temperature detection module and a humidity sensing module. In the entire circuit for controlling the balanced charge and discharge of the battery string, the current sampling module, the voltage sampling module, the temperature detection module, the humidity detection module and the control module all need to be continuously and normally powered to facilitate the normal operation of the above modules. Considering cost and for the convenience of installation and actual application scenarios, the corresponding single cells in the battery string can be directly used to supply power to the above modules.

[0228] In one embodiment, the current sampling module, the voltage sampling module, the temperature detection module, and the humidity detection module are all connected to the control module, and the current sampling module, the voltage sampling module, the temperature detection module, and the humidity detection module are arranged on the same integrated circuit board. The positive electrode and the negative electrode are led out through the integrated circuit board and connected to the positive electrode and the negative electrode of a certain single battery respectively to supply power to the entire integrated circuit board. Among them, the control module is powered separately.

[0229] In one embodiment, taking four single batteries as an example, as Figure 46 shown, the positive electrode and the negative electrode of the integrated circuit board are respectively connected to the positive electrode and the negative electrode of each single battery. A third control switch (such as n1, etc.) is provided between the positive electrode of each single battery and the positive electrode of the integrated circuit board, and a fourth control switch (such as n2, etc.) is provided between the negative electrode of each single battery and the negative electrode of the integrated circuit board. That is, by controlling n1 and n2 at both ends of the corresponding single battery, the acquisition circuit board can be powered by the single battery. Generally speaking, the working voltage of each device in the acquisition circuit board can be provided by only one single battery to meet the normal working requirements. Among them, the third control switch and the fourth control switch are both MOS tubes controlled by the PWM signal output by the control module.

[0230] According to the above example, in order to ensure that the voltage difference between each single battery is minimized when the battery string fails or does not work in the photovoltaic module and to maintain the stability of the battery string, and to achieve the charge balance of each single battery in the battery string, the state of charge of each single battery is obtained according to the sampled voltage and the sampled current collected by the voltage acquisition module and the current acquisition module. The control module controls the corresponding third control switch and fourth control switch to conduct, so as to supply power to the integrated circuit board through the single battery with the highest charge amount. Since a certain amount of power is consumed during the working process of each device in the integrated circuit board, the charge balance of each single battery is realized from another aspect to maintain the stability of the battery string.

[0231] In one embodiment, during the charging process, when a certain single battery is always charged earlier than other single batteries according to the characteristics of the single battery, the third control switch and the fourth control switch corresponding to both ends of the single battery are selected to conduct, so as to supply power to the integrated circuit board through the single battery.

[0232] In one embodiment, if it is detected that the state of charge of the single battery currently supplying power to the integrated circuit board is lower than a preset value compared with the state of charge of other single batteries, it is necessary to switch to other single batteries to supply power to the integrated circuit board to prevent the single battery from being over-discharged. The corresponding third control switch and fourth control switch are controlled to disconnect, and the third control switch and the fourth control switch at both ends of the single battery with the largest state of charge are re-conducted to maintain the stability of the battery string.

[0233] In one embodiment, as Figure 47 shown, the voltage sampling module includes a plurality of voltage mapping units, a multiplexer, and an analog-to-digital converter. The voltage mapping units are connected in parallel with each single cell. The voltage mapping units are connected in series with the multiplexer. The input end of the analog-to-digital converter is connected to the multiplexer. The output end of the analog-to-digital converter is connected to the control module. The control module is also connected to the multiplexer.

[0234] In one embodiment, as Figure 48 shown, the voltage mapping unit includes: a resistor R1, a capacitor C1, a capacitor C2, a zener diode D1, a field effect transistor Qs, and a transformer. Wherein, the first end of the capacitor C1 is connected to the CLK terminal, and its second end is respectively connected to the first end of the resistor R1, the cathode of the zener diode D1, and the gate of the field effect transistor Qs. The second end of the resistor R1, the first end of the capacitor C2, the anode of the zener diode D1, and the source of the field effect transistor Q1 are connected to the negative electrode of the corresponding single cell. The positive electrode of the corresponding single cell is connected to the first end of the primary coil in the transformer. The second end of the primary coil is respectively connected to the second end of the capacitor C2 and the drain of the field effect transistor Q1. The first end of the secondary coil in the transformer is connected to the multiplexer, and the second end of the secondary coil is grounded.

[0235] Wherein, when the clock CLK is turned on, the voltages across all the single cells in the battery string will be mapped to the secondary coil of the transformer through the transformer. The entire circuit operates under the drive of a unified clock CLK. A capacitor C1 and a resistor R1 are added to the drive circuit of the gate of the field effect transistor Qs, so that the gate voltage can follow the change of the source of the field effect transistor Qs, and the square wave signal of the CLK can be transmitted to the gate. At the same time, the zener diode D1 is used to protect the gate-source voltage to avoid damage to the field effect transistor Qs.

[0236] In a battery string including N single cells, in the connection lines corresponding to the non-terminal single cells, the currents in the upper and lower adjacent loops may cancel each other out. Therefore, the parasitic resistance of the cable has little influence on the voltage sampling of the non-terminal battery cells. The sampling accuracy is basically only affected by the on-resistance Rmos-i of the field effect transistor Qs and the parasitic resistance RLa-i of the transformer inductance. Therefore, the expression of its sampling voltage is as follows:

[0237] VSAMPi = Vin i+ -Vin i- -I × (Rmosi + RLia), i ≠ 1, i ≠ N;

[0238] Among them, VSAMPi represents the voltage across the i-th single battery cell, Vin+ represents the positive voltage of the i-th single battery cell, Vin- represents the negative voltage of the i-th single battery cell, I represents the current in the primary coil circuit at the sampling moment, Rmosi represents the on-resistance of the field effect transistor Qs, and RLiai represents the parasitic resistance of the primary coil of the transformer.

[0239] For the single battery cells located at both ends of the battery string, the current in a set of cable parasitic impedances in its loop cannot be canceled out with adjacent single cells. Therefore, the expression for its sampled voltage is as follows:

[0240] VSAMPi = Vin i+ -Vin i- -I×(Rx + Rmosi + RLia), i = 1, i = N;

[0241] Among them, VSAMPi represents the voltage across the i-th single battery cell, Vin+ represents the positive voltage of the i-th single battery cell, Vin- represents the negative voltage of the i-th single battery cell, I represents the current in the primary coil circuit at the sampling moment, Rx represents the parasitic impedance of the connection between the primary coil circuit and the battery, Rmosi represents the on-resistance of the field effect transistor Qs, and RLiai represents the parasitic resistance of the primary coil of the transformer.

[0242] According to the above method, the voltage across each single battery cell in the battery string can be obtained. The voltage obtained by this method cannot be directly used as the sampled voltage across the single battery cell to judge the state of charge of the single battery cell. The contact resistance of the single battery cell also needs to be considered. For details, refer to the above embodiments and will not be elaborated in this embodiment.

[0243] For the specific process of the method for controlling the balanced charge and discharge of the battery string, refer to the above embodiments and will not be elaborated here.

[0244] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for controlling the balanced charging and discharging of a battery string, characterized in that, It is implemented in the charge and discharge loop of the battery string. Among them, a first switch is respectively arranged between the positive electrode of the charge and discharge module for controlling the charge and discharge of the battery string and the positive electrode of each single battery in the battery string, and a second switch is respectively arranged between the negative electrode of the charge and discharge module and the negative electrode of each single battery in the battery string. The method includes: Obtain the sampled voltage across each single battery and the sampled current in the charge and discharge loop of the battery string; Respectively control the conduction states of the first switch and the second switch corresponding to the respective single batteries according to the sampled voltage and the sampled current, so as to select to charge and discharge the single batteries that meet the charge and discharge requirements respectively.

2. The method for controlling the balanced charge and discharge of a battery string according to claim 1, wherein The method further includes: In the charging state, respectively judge whether the state of charge of each single battery is in a fully charged state or an incompletely charged state according to the sampled voltage and the sampled current; Disconnect the first switch and the second switch at both ends of the first single battery in the fully charged state; Turn on the first switch and the second switch at both ends of the second single battery in the incompletely charged state, and control the charge and discharge module to charge the second single battery until it is detected that the state of charge of the second single battery reaches the fully charged state; or, obtain the connection relationship of the second single batteries in the incompletely charged state. If there are at least two second single batteries forming a series relationship, form a series battery pack with at least two second single batteries, and turn on the first switch and the second switch corresponding to the series battery pack.

3. The method for controlling the balanced charging and discharging of a battery string according to claim 1, characterized in that The method further includes: In the discharging state, respectively judge whether the state of charge of each single battery is in a fully discharged state or an incompletely discharged state according to the sampled voltage and the sampled current; Disconnect the first switch and the second switch at both ends of the third single battery in the fully discharged state; turn on the first switch and the second switch at both ends of the fourth single battery in the incompletely discharged state, and control the charge and discharge module to discharge the fourth single battery until it is detected that the state of charge of the fourth single battery reaches the fully discharged state; or, obtain the connection relationship of the second single batteries in the incompletely discharged state. If there are at least two second single batteries forming a series relationship, form a series battery pack with at least two second single batteries, and turn on the first switch and the second switch corresponding to the series battery pack.

4. The method for controlling the balanced charge and discharge of a battery string according to claim 1, wherein An energy storage module is arranged between each first switch and the positive electrode of the corresponding single battery, and each energy storage module is equipped with a corresponding control switch. The method further includes: When the charge and discharge module cannot support charging the remaining single batteries that are still in the incompletely charged state, turn off the charge and discharge module, and respectively obtain the state of charge of each single battery according to the sampled voltage and the sampled current; Compare the magnitudes of the states of charge between adjacent two single batteries, and by controlling the conduction states of the first switch, the second switch and the control switches of the corresponding energy storage modules, enable the single battery with a larger state of charge to charge the corresponding energy storage unit; After presetting a charging time for the energy storage unit, by controlling the conduction states of the first switch, the second switch, and the control switch of the corresponding energy storage unit, the charged energy storage unit is used to charge the single battery with a smaller state of charge.

5. The method for controlling the balanced charge and discharge of a battery string according to claim 1, characterized in that, The method further includes: When the charge and discharge module can only support charging the remaining single battery, select the single battery with the lowest voltage for charging according to a preset period to continuously increase the power of the single battery with the lowest voltage and reduce the voltage difference between each single battery.

6. The method for controlling the balanced charging and discharging of a battery string according to claim 1, wherein The method further includes: During the discharge process of the battery string, evaluate the maximum discharge current that each single battery can accept, and control the charge and discharge module to perform series discharge according to the minimum value of the maximum discharge currents.

7. The method for controlling the balanced charge and discharge of a battery string according to claim 1, wherein The method further includes: before the charge and discharge process of the battery string, detect the contact resistance of each single battery in the battery string, specifically including: Obtain the open-circuit voltage of each single battery in the battery string in the open-circuit state; Output a short-term constant current through a constant current source to charge the battery string, and obtain the collected voltage across each single battery during the charging process; Obtain the contact resistance of the corresponding single battery according to the open-circuit voltage, the short-term constant current, and the collected voltage.

8. The method for controlling the balanced charge and discharge of a battery string according to claim 1, characterized in that The method further includes: During the charging process, the calculation method of the sampling voltage is: Vc = Vm - Ic * Rc; During the discharging process, the calculation method of the sampling voltage is: Vc = Vm + Ic * Rc; Wherein, Vc is the sampling voltage, Vm is the voltage value actually collected across each single battery, Ic is the sampling current, and Rc is the contact resistance corresponding to the corresponding single battery.

9. A circuit for controlling the balanced charging and discharging of a battery string, characterized in that, A method for controlling the balanced charge and discharge of a battery string as described in any one of claims 1-8, including: a control module, a charge and discharge module, a voltage sampling module, a current sampling module, and a switch module. The positive electrode of the charge and discharge module is connected to the positive electrode of the battery string, and the negative electrode of the charge and discharge module is connected to the negative electrode of the battery string; The switch module includes a first switch disposed between the positive electrode of each single battery and the positive electrode of the charge and discharge module, and a second switch disposed between the negative electrode of each single switch and the negative electrode of the charge and discharge module; The sampling points of the voltage sampling module are respectively connected to the positive and negative electrodes of each single battery; the current acquisition module is connected in series in the main circuit of the charge and discharge module; The control module is respectively connected to the control terminals of the charge and discharge module, the voltage sampling module, the current sampling module, and each switch in the switch module; The charge and discharge module is used to charge or discharge the battery string according to the instructions of the control module; The voltage sampling module is used to respectively obtain the sampling voltage across each single battery, and the current sampling module is used to obtain the sampling current in the main charge and discharge circuit of the battery string; The control module is used to respectively control the conduction states of the first switch and the second switch corresponding to the corresponding single battery according to the sampling voltage and the sampling current, so as to select and charge and discharge the single batteries that meet the charge and discharge requirements respectively, and achieve the charge and discharge balance of each single battery in the charge and discharge state of the battery string.

10. The circuit for controlling the balanced charge and discharge of a battery string according to claim 9, characterized in that, It further includes energy storage modules disposed in the charge and discharge circuits of each single battery, and each energy storage module includes an energy storage unit, a first control switch, and a second control switch; One ends of the first control switch and the second control switch are respectively connected to one end of the first switch, the other end of the first control switch is connected to one end of the energy storage unit, and the other end of the energy storage unit and the other end of the second control switch are respectively connected to the positive electrodes of each single battery.

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