Battery string contact resistance self-checking method and device

Abstract

The invention relates to the technical field of battery contact resistance self-checking, in particular to a battery string contact resistance self-checking method and device, and the method comprises the steps: obtaining the open-circuit voltage of the two ends of each single battery in a battery string in an open-circuit state; a short-time constant current is output through a constant current source so as to charge the battery string, and acquisition voltages at the two ends of each single battery are acquired in the charging process; and finally, obtaining the contact resistance of the corresponding single battery according to the open-circuit voltage, the short-time constant current and the acquired voltage. Short-time constant current passes through a battery string, so that each single battery generates a voltage drop caused by contact resistance, the problem that the contact resistance is too high due to operation when the battery string is assembled can be detected, whether the single batteries are correctly mounted or not is automatically judged, and the whole system is simple in structure, easy to detect and operate and low in cost. And different detection nodes can be flexibly controlled to automatically detect the contact resistance of different single batteries.

Description

Technical Field

[0001] The present invention relates to the technical field of self-checking of battery contact resistance, and particularly to a method and device for self-checking the contact resistance of a battery string. Background Art

[0002] During the actual installation process of a battery string, the contact between single cells may be poor, which may lead to an excessive contact resistance of the battery, wasting charge and discharge energy, and affecting the assessment of the battery power. As a result, the battery may be judged as fully charged when it is not, or judged as discharged when the battery power has not been completely drained. At the same time, various links are experienced from production to successful installation, and accidental bumps may cause poor contact. Even if the contact resistance is good at the time of successful installation, it cannot be guaranteed that the contact resistance will not increase after subsequent wind and rain.

[0003] In traditional battery contact resistance detection, static or manual methods are usually used for inspection. This method is not only inefficient but also prone to errors in the detection results due to human factors. Although existing self-checking methods for contact resistance indirectly detect the contact resistance through voltage, current or temperature monitoring, it is often difficult to achieve real-time, accurate and automated self-checking.

[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 provide a self-checking method that can detect the contact resistance of a battery string in real time and automatically determine whether the single cells are correctly installed.

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

[0007] In a first aspect, a method for self-checking the contact resistance of a battery string is provided, including:

[0008] Obtaining the open-circuit voltage across each single cell in the battery string in an open-circuit state;

[0009] Outputting a short-term constant current through a constant current source to charge the battery string, and obtaining the collected voltage across each single cell during the charging process;

[0010] Obtaining the contact resistance of the corresponding single cell according to the open-circuit voltage, the short-term constant current, and the collected voltage.

[0011] Preferably, the self-checking method for the contact resistance of the battery string is applied to a battery string, which includes batteries and a battery string assembly structure. The battery 3 is arranged in the battery string assembly structure, and the contact resistance is generated by the connecting and conductive components in the battery string assembly structure. The battery string assembly structure includes: at least one series connection rod 1 and a plurality of connecting and conductive components 2;

[0012] Each connecting and conductive component 2 is connected in series on the series connection rod 1;

[0013] Moreover, a reserved space is arranged between every two connecting and conductive components 2 for accommodating the battery 3 and directly contacting the positive or negative electrode of the battery 3;

[0014] Each connecting and 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.

[0015] Preferably, the connecting and conductive component 2 includes a connecting component 21, a battery conductive structure 22, and an external conductive structure 23 extended from the battery conductive structure 22;

[0016] The battery conductive structure 22 is installed on the connecting component 21, and the connecting component 21 is connected in series on the series connection rod 1;

[0017] The battery conductive structure 22 directly contacts the positive or negative electrode of the battery 3;

[0018] The external conductive structure 23 is used for connecting the external circuit 4 to realize the coupling between the battery 3 and the external circuit 4.

[0019] Preferably, the connecting component 21 includes a connecting piece 211 and a fixing ring 212;

[0020] At least one inserting piece 2110 is arranged at at least one end of the connecting piece 211; at least one slot 2120 is arranged on the ring wall of the fixing ring 212, and the slot 2120 matches the inserting piece 2110;

[0021] The inserting piece 2110 is inserted into the slot 2120 to install the connecting piece 211 inside the ring of the fixing ring 212 and make the connecting piece 211 perpendicular to the axis of the fixing ring 212;

[0022] At least one protruding part 2121 is arranged on the outer wall of the fixing ring 212, and a channel 21210 parallel to the axis of the fixing ring 212 is arranged on the protruding part 2121. The series connection rod 1 is inserted into the channel 21210 to connect the connecting component 21 in series;

[0023] The connecting piece 211 is used for providing an installation position for the battery conductive structure 22.

[0024] Preferably, the battery conductive structure 22 includes a first conductive sheet 221 and a second conductive sheet 222 which are oppositely arranged, and a first connecting portion 223 connecting the first conductive sheet 221 and the second conductive sheet 222;

[0025] A placement groove 2111 matching the first connecting portion 223 is provided on the connecting sheet 211;

[0026] One side of the placement groove 2111 is provided with an opening 2112, and the opening 2112 penetrates to the edge of the connecting sheet 211, so that the first connecting 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 connecting surface of the connecting sheet 211, and the second conductive sheet 222 is located on the second connecting surface of the connecting sheet 211; wherein, the first connecting surface and the second connecting surface are two opposite connecting surfaces of the connecting sheet 211;

[0027] The first conductive sheet 221 is in direct contact with the battery 3 on the side where the first connecting surface is located;

[0028] The second conductive sheet 222 is in direct contact with the battery 3 on the side where the second connecting surface is located.

[0029] Preferably, the external conductive structure 23 is a connecting pipe;

[0030] The connecting pipe is used for inserting an external circuit 4 therein to realize the connection with the external circuit 4.

[0031] Preferably, a buckle 2122 is provided on the outer wall of the fixing ring 212; the connecting pipe is inserted into the buckle 2122 to realize the fixation of the connecting pipe.

[0032] Preferably, the protruding portion 2121 includes a first sub-protruding portion 21211 and a second sub-protruding portion 21212;

[0033] The pore channel 21210 includes a first sub-pore channel 212101 provided on the first sub-protruding portion 21211 and a second sub-pore channel 212102 provided on the second sub-protruding portion 21212;

[0034] The first sub-protruding portion 21211 and the second sub-protruding portion 21212 are oppositely arranged, and the first sub-pore channel 212101 and the second sub-pore channel 212102 are oppositely arranged;

[0035] A gap is provided between the first sub-protruding portion 21211 and the second sub-protruding portion 21212 to form the slot 2120;

[0036] The insert piece 2110 is provided with a first through hole 21101 at a position aligned with the first sub-channel 212101 and the second sub-channel 212102, so that the series connection rod 1 passes through the first through hole 21101 when inserted into the channel 21210.

[0037] Preferably, the method further includes:

[0038] During the charging process of the battery string, the calculation method of the sampling voltage at both ends of each single battery in the battery string is: Vc = Vm - Ic * Rc;

[0039] During the discharging process of the battery string, the calculation method of the sampling voltage is: Vc = Vm + Ic * Rc;

[0040] Wherein, Vc is the sampling voltage, Vm is the voltage value actually collected at both ends of each single battery, Ic is the sampling current, and Rc is the contact resistance corresponding to the corresponding single battery.

[0041] In a second aspect, a battery string contact resistance self-checking device is provided, which is used to implement the battery string contact resistance self-checking method as described in the first aspect, and includes: a first acquisition module, a second acquisition module, and a third acquisition module;

[0042] The first acquisition module is used to acquire the open-circuit voltage at both ends of each single battery in the battery string in the open-circuit state;

[0043] The second acquisition module is used to output a short-term constant current through a constant current source to charge the battery string, and acquire the collected voltage at both ends of each single battery during the charging process;

[0044] The third acquisition module is used to obtain the contact resistance of the corresponding single battery according to the open-circuit voltage, the short-term constant current, and the collected voltage.

[0045] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0046] The present invention acquires the open-circuit voltage at both ends of each single battery in the battery string in the open-circuit state; outputs a short-term constant current through a constant current source to charge the battery string, and acquires the collected voltage at both ends of each single battery during the charging process; finally, obtains the contact resistance of the corresponding single battery according to the open-circuit voltage, the short-term constant current, and the collected voltage. The short-term constant current is passed through the battery string to cause a voltage drop due to the contact resistance for each single battery, which can detect the problem of too high contact resistance caused by operation during the assembly of the battery string, automatically judge whether the single battery is correctly installed, the whole system has a simple structure, the detection operation is easy, and different detection nodes can be flexibly controlled to automatically detect the contact resistance of different single batteries. Description of the Drawings

[0047] 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 use in 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 also be obtained based on these drawings.

[0048] Figure 1 is a schematic structural diagram of a battery string assembly structure provided by an embodiment of the present invention;

[0049] Figure 2 is a schematic structural diagram of a battery string assembly structure provided by an embodiment of the present invention;

[0050] Figure 3 is a schematic structural diagram of a connection conductive component in a battery string assembly structure provided by an embodiment of the present invention;

[0051] Figure 4 is a schematic structural diagram of a connection conductive component in a battery string assembly structure provided by an embodiment of the present invention;

[0052] Figure 5 is a schematic structural diagram of a connection component in a battery string assembly structure provided by an embodiment of the present invention;

[0053] Figure 6 is a schematic structural diagram of a connection piece in a battery string assembly structure provided by an embodiment of the present invention;

[0054] Figure 7 is a schematic structural diagram of a connection piece in a battery string assembly structure provided by an embodiment of the present invention;

[0055] Figure 8 is a partial structural schematic diagram of a battery string assembly structure provided by an embodiment of the present invention;

[0056] Figure 9 is a schematic structural diagram of a fixing ring in a battery string assembly structure provided by an embodiment of the present invention;

[0057] Figure 10 is a schematic structural diagram of a fixing ring in a battery string assembly structure provided by an embodiment of the present invention;

[0058] Figure 11 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;

[0059] Figure 12 is a schematic structural diagram of a connection piece in a battery string assembly structure provided by an embodiment of the present invention;

[0060] Figure 13 It is a schematic structural diagram of a connecting piece in a battery string assembly structure provided by an embodiment of the present invention;

[0061] Figure 14 It is a schematic structural diagram of a battery conductive structure and an external conduction point structure in a battery string assembly structure provided by an embodiment of the present invention;

[0062] 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;

[0063] Figure 16 It is a schematic structural diagram of a connecting and conductive component in a battery string assembly structure provided by an embodiment of the present invention;

[0064] 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;

[0065] Figure 18 It is a schematic structural diagram of a battery conductive structure and an external conduction point structure in a battery string assembly structure provided by an embodiment of the present invention;

[0066] Figure 19 It is a schematic structural diagram of a battery conductive structure and an external conduction point structure in a battery string assembly structure provided by an embodiment of the present invention;

[0067] 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;

[0068] 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;

[0069] 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;

[0070] Figure 23 It is a schematic structural diagram of a battery string assembly structure provided by an embodiment of the present invention;

[0071] Figure 24 It is a partial structural schematic diagram of a battery string assembly structure provided by an embodiment of the present invention;

[0072] 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;

[0073] Figure 26 It is a partial structural schematic diagram of a battery string assembly structure provided by an embodiment of the present invention;

[0074] Figure 27 It is a schematic structural diagram of a locking component in a battery string assembly structure provided by an embodiment of the present invention;

[0075] 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;

[0076] 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;

[0077] 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;

[0078] Figure 31 It is a schematic structural diagram of a battery string provided by an embodiment of the present invention;

[0079] 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;

[0080] 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;

[0081] 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;

[0082] 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;

[0083] 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;

[0084] Figure 37 It is a schematic flowchart of a process for battery mutual charging to balance battery power provided by an embodiment of the present invention;

[0085] Figure 38 It is a schematic structural diagram of a circuit for battery mutual charging provided by an embodiment of the present invention;

[0086] Figure 39 It is a schematic flowchart of a method for self-checking the contact resistance of a battery string provided by an embodiment of the present invention;

[0087] 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;

[0088] Figure 41It 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;

[0089] 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;

[0090] Figure 43 It is a structural schematic diagram of an energy storage module provided by an embodiment of the present invention;

[0091] 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;

[0092] Figure 45 It is a structural schematic diagram of charging a single battery through an energy storage unit provided by an embodiment of the present invention;

[0093] 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;

[0094] Figure 47 It is a structural schematic diagram of a voltage sampling module provided by an embodiment of the present invention;

[0095] Figure 48 It is a structural schematic diagram of a voltage mapping unit provided by an embodiment of the present invention;

[0096] Figure 49 It is a structural schematic diagram of a battery string contact resistance self-checking device provided by an embodiment of the present invention.

[0097] In all the drawings, the same reference numerals are used to denote the same elements or structures, where:

[0098] 1. Connecting rod; 11. First connecting rod; 12. Second connecting rod; 2. Connecting and conducting component; 21. Connecting component; 211. Connecting piece; 2110. Insertion 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. Snap; 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. Link 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 mode

[0099] 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 in conjunction with 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.

[0100] Unless otherwise required by the context, in the entire specification and claims, the term "including" is interpreted as an open and inclusive meaning, that is, "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 referring 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 appropriate manner, that is, although they may be carried in the above-mentioned embodiments or examples due to reasons such as the order and position of appearance, they are not limited to being carried by one embodiment or example in a combined manner.

[0101] In the description of the present invention, the terms "first" and "second" are used only 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, the 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 specified, the meaning of "a plurality" is two or more. In addition, for the same type of nouns in the description, they are described as two independent individuals by adding "A" and "B" at the end. 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.

[0102] In the description of some embodiments, the expressions "coupled", "coupled to" and "connected" and their derivatives may be used. For example, in the description of some embodiments, the term "connected" may be used to indicate that two or more components have direct physical or electrical contact with each other. Again, in the description of 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.

[0103] 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.

[0104] Embodiment 1:

[0105] The method for self-checking the contact resistance of a battery string proposed by the present invention is applied to a battery string. Before specifically describing the method for self-checking the contact resistance of the battery string proposed by the present invention, a battery string is first introduced. The battery string includes a battery and a battery string assembly structure. The battery is disposed in the battery string assembly structure. The contact resistance is generated by the connecting conductive components in the battery string assembly structure. In one embodiment, as Figure 1 and Figure 2 shown, the battery string assembly structure 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 the battery 3 and making direct contact with the positive or negative electrode of the battery 3; each connecting conductive component 2 is further used for connecting an external circuit 4 to realize the coupling between the battery 3 and the external circuit 4.

[0106] In actual use, the connecting rod 1 can be one; for ensuring stability, the number of the connecting rods 1 can be two, and two connecting rods 1 form a relatively stable bracket, as Figure 1 and Figure 2 shown, 7 connecting and conducting 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 no battery is installed, Figure 2 is a schematic diagram in the state where a battery is installed.

[0107] In this embodiment, the connecting rods 1 are used to form a connecting bracket, and each connecting and conducting component 2 forms a connecting member for coupling the battery 3 and the external circuit 4. Thus, without welding the battery 3 and the external circuit 4, the coupling between the battery 3 and the external circuit 4 can be achieved. In the implementation manner of this embodiment, when a corresponding battery has a problem, the battery can be directly taken out and replaced without disassembling the connecting rod 1, other batteries in the battery string, and the connecting and conducting component 2, thereby saving manpower and material resources.

[0108] In an alternative implementation manner, as Figure 3 and Figure 4 shown, the connecting and conducting component 2 includes a connecting component 21, a battery conducting structure 22, and an external conducting structure 23 extending from the battery conducting structure 22; the battery conducting structure 22 is installed on the connecting component 21, and the connecting component 21 is connected in series on the connecting rod 1; the battery conducting structure 22 is in direct contact with the positive or negative electrode of the battery 3; the external conducting structure 23 is used to connect the external circuit 4 to achieve the coupling between the battery 3 and the external circuit 4.

[0109] Among them, Figure 3 and Figure 4 are respectively the front schematic diagram and the back schematic diagram of the connecting and conducting component 2. The connection of the connecting component 21 in series on the connecting rod 1 can be achieved through through-holes, channels, or other fixing structures (such as buckles, etc.).

[0110] In a preferred implementation manner, as Figure 5 shown, the connecting component 21 includes a connecting piece 211 and a fixing ring 212; as Figure 6 shown, at least one inserting piece 2110 is provided at at least one end of the connecting 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 inserting piece 2110; the inserting piece 2110 is inserted into the slot 2120 to install the connecting piece 211 inside the ring of the fixing ring 212 and make the connecting piece 211 perpendicular to the axial direction of the fixing ring 212 (i.e., the direction of the connecting rod 1); as Figure 10As shown, the outer wall of the fixing ring 212 is provided with at least one protrusion 2121, and the protrusion 2121 is provided with a channel 21210 axially parallel to the fixing ring 212. The connecting rod 1 is inserted into the channel 21210 to connect the connecting assembly 21 in series; the connecting piece 211 is used to provide an installation position for the battery conductive structure 22.

[0111] 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.

[0112] 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.

[0113] 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.

[0114] In a specific application scenario, such as Figure 11As shown, the battery conductive structure 22 includes a first conductive sheet 221 and a second conductive sheet 222 that are oppositely arranged, and a first connecting portion 223 that connects the first conductive sheet 221 and the second conductive sheet 222; as Figure 12 As shown, a placement groove 2111 matching the first connecting portion 223 is provided on the connecting sheet 211; an opening 2112 is provided on one side of the placement groove 2111, and the opening 2112 penetrates to the edge of the connecting sheet 211, so that the first connecting 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 connecting surface of the connecting sheet 211, and the second conductive sheet 222 is located on the second connecting surface of the connecting sheet 211; wherein, the first connecting surface and the second connecting surface are two opposite connecting surfaces of the connecting sheet 211; the first conductive sheet 221 is in direct contact with the battery 3 on the side where the first connecting surface is located; the second conductive sheet 222 is in direct contact with the battery 3 on the side where the second connecting surface is located.

[0115] It should be noted here that this embodiment is for the connecting conductive component 2 in the middle. When the connecting conductive component 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.

[0116] Wherein, the inner wall of the placement groove 2111 is designed to be arc-shaped to prevent damage to the first connecting portion 223 and the placement groove 2111 when the first connecting portion 223 shakes in the placement groove 2111.

[0117] 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 connecting sheet 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 analyzing the structural characteristics of the battery conductive structure 22. After the first connecting portion 223 is placed in the placement groove 2111, the first conductive sheet 221 can have a larger area located on the first connecting surface, and the second conductive sheet 222 can have a larger area located on the second connecting 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 conductive structure 22 is installed on the connecting sheet 211. In actual use, the placement groove 2111 can be set at a position close to the edge of the connecting sheet 211, so that the other edge position of the connecting sheet 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.

[0118] The battery conductive structure 22 may be a U-shaped piece that can be bent from the first connection portion 223, and the direction opposite to the first connection portion 223 is an opening; in another embodiment, as Figure 14 As 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.

[0119] 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 part 223 of the battery conductive structure 22 can be smoothly installed into the placement groove 2111, and the first connection part 223 does not have a large displacement in the placement groove 2111.

[0120] 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 to insert the external line 4 therein to realize the connection with the external line 4.

[0121] 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 inserting the external line 4 into the connecting pipe, the connection with the external line 4 is realized 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.

[0122] 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 realize the fixation of the connecting pipe.

[0123] And, in order to ensure that after the first connection part 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 part 225 of the battery conductive structure 22. The extension part 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 part 225 is relatively small, as Figure 19 shown, the width W5 of the extension part 225 is smaller 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 part 225, such as in Figure 19 the width of the second connection part 224 gradually decreases. The buckle 2122 can be a closed full-ring buckle or a partial-ring buckle with an opening.

[0124] 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 relatively arranged on both sides of the inner wall of the buckle (such as being arranged on the left and right sides of the buckle, as shown in Figure 17), and the first groove 21221 and the second groove 21222 are smoothly connected with other parts of the inner wall. The depth of the first groove 21221 and the depth of the second groove 21222 are determined by those skilled in the art based on demand analysis. The first groove 21221 and the second groove 21222 facilitate the insertion of the external circuit 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 being broken by force and extending the service life of the buckle. In actual use, the inner ring diameter r of the buckle is slightly smaller than the outer diameter R of the external circuit. The depth of the first groove 21221 and the depth of the second groove 21222 are D, then r+2D≥R, and usually r+2D is slightly larger than R.

[0125] This embodiment also provides a preferred implementation method. Figure 20 As shown, the protrusion 2121 includes a first sub-protrusion 21211 and a second sub-protrusion 21212; the channel 21210 includes a first sub-channel 212101 provided on the first sub-protrusion 21211 and a second sub-channel 212102 provided on the second sub-protrusion 21212; the first sub-protrusion 21211 and the second sub-protrusion 21212 are arranged opposite to each other, and the first sub-channel 212101 and the second sub-channel 212102 are arranged opposite to each other; a gap is provided between the first sub-protrusion 21211 and the second sub-protrusion 21212 to form the slot 2120; Figure 21 As shown, the insert 2110 is provided with a first through hole 21101 at a position aligned with the first sub-channel 212101 and the second sub-channel 212102 , so that the connecting rod 1 passes through the first through hole 21101 when inserted into the channel 21210 .

[0126] In actual application scenarios, there are two inserts 2110, and a first through hole 21101 is provided on each insert 2110, so that the serial rod 1, the connecting piece 211 and the fixing ring 212 together form a stable structure, and the two inserts 2110 are arranged relative to each other. Since errors may occur during the device manufacturing process, and the fixing ring 212 needs to be pried apart when the connecting piece 211 is installed in the fixing ring 212, and the fixing ring 212 may also have slight deformation after elastic recovery, this embodiment also provides a preferred implementation method, that is, the first through hole 21101 is a waist-shaped hole (that is, a hole with arcs at both ends), and the two ends of the waist-shaped hole are in the direction of the connection line of the two inserts 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 channel 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

[0127] In an actual application scenario, the radial length of the fixing ring 212 (i.e., the thickness of the fixing ring 212, i.e., Figure 22 d5 in

[0128] In an alternative embodiment, as Figure 23 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 Figure 24 and Figure 25 shown, the locking assembly 5 includes a connecting rod 51, a first screw 52 and a second screw 53; the locking assembly 5 is arranged at both ends of the connecting rod 1; in actual use, it is shown as having two locking assemblies 5, one locking assembly 5 is arranged at one end of the connecting rod 1, and the other is arranged at the other end of the connecting rod 1 to realize the locking of the connecting rod 1, each battery 3 and each connecting conductive component 2.

[0129] The rod bodies of the first connecting rod 11 and the second connecting rod 12 are provided with threads; the connecting rod 51 is provided with a second through hole 511 and a third through hole 512; the first connecting rod 11 passes through the second through hole 511, and the second connecting rod 12 passes through the third through hole 512 to limit and fix the relative positions between the first connecting rod 11 and the second connecting rod 12; the first screw 52 is screwed into the first connecting rod 11, and the second screw 53 is screwed into the second connecting rod 12 to keep the connecting rod 51, the first connecting rod 11, the second connecting rod 12, the connecting conductive component 2 and each battery 3 in a fixed position by tightening the first screw 52 and the second screw 53.

[0130] In a preferred embodiment, in order to accommodate errors and deformations, the second through hole 511 and the third through hole 512 are both waist-shaped holes.

[0131] like Figure 26 and Figure 27 As shown, the locking assembly 5 also includes a third screw 54 and a fourth screw 55. The third screw 54 and the fourth screw 55 are arranged on the inner side of the connecting conductive assembly 2 located at both ends of the serial rod 1, that is, on the side close to the middle of the serial 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 achieving structural reinforcement. The connecting rod 51 is also designed with an abutment block 513. The abutment 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). This is because the presence of the fixing ring 212 makes it possible for the locking assembly 5 to only abut against the protrusion on the fixing ring 212 when the locking assembly 5 is locked, and cannot apply abutment pressure to the center of the connecting conductive assembly 2. In order to further enhance the stability of the structure, the abutment block 513 is provided to fill the gap between the connecting rod 51 and the center of the connecting conductive assembly 2, thereby abutting and fixing the center of the connecting conductive assembly 2. The thickness of the abutment block 513 is greater than or equal to the distance between the connecting rod 51 and the center of the connected conductive component 2 .

[0132] In some embodiments, the radial length of the protrusion 2121 (ie, the thickness of the protrusion 2121, i.e. Figure 22 d6) is smaller than the radial length of the fixing ring 212 (ie Figure 22 d5 in the .

[0133] In actual use, such as Figure 28 and Figure 29 As shown, the structure of this embodiment further includes a housing 6, which includes a cylindrical shell 61, a bottom cover 62, and a wiring cover 63. The cylindrical shell 61 surrounds the serial rod 1, multiple connecting conductive components 2, and the battery 3. The bottom cover 62 and the wiring cover 63 are respectively disposed at both ends of the cylindrical shell 61. Both 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 that match the first threads to enable the bottom cover 62 and the cylindrical shell 61 to be tightened, and the wiring cover 63 and the cylindrical shell 61 to be tightened. The outer walls of the wiring cover 63 and the bottom cover 62 are also provided with textures to increase friction when tightened by hand.

[0134] Furthermore, the wiring cover 63 is provided with a wiring hole (not shown in the figure) and a pressure relief hole (not shown in the figure). The external line 4 passes through the wiring hole to connect to the connecting conductive component 2 inside the housing 6. The pressure relief hole is used to relieve pressure when opened to ensure that the air pressure inside and outside the housing 6 is consistent.

[0135] A wiring cap 631 is correspondingly provided for the wiring hole to close the wiring hole when not in use, and a pressure relief cap 632 is correspondingly provided for the pressure relief hole to close 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.

[0136] 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

[0137] Embodiment 2:

[0138] 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.

[0139] 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 charge and discharge of the battery string, which is implemented in the charge and discharge circuit 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, as Figure 32 shown, and the method includes:

[0140] Step 101: Obtain the sampled voltage across each single battery and the sampled current in the charge and discharge circuit of the battery string.

[0141] Among them, to obtain the sampled voltage across each single battery, sampling points need to be set at the positive and negative electrodes of each single battery. Since the battery string is composed of multiple single batteries connected in series, sampling points need to be set at the connection points between adjacent single batteries, the positive electrode of the first single battery, and the negative electrode of the last single battery. By calculating the voltage difference between adjacent sampling points, the sampled voltage across each single battery 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.

[0142] Step 102: Control the on-off 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 selectively charge and discharge the single batteries that meet the charge and discharge requirements.

[0143] Among them, the single battery meeting the charge and discharge requirements refers to that after obtaining the state of charge of each single battery according to the sampled voltage and sampled current, during the charging process, the fully charged single batteries and the uncharged single batteries are judged according to the corresponding state of charge, and by controlling the corresponding first switch and second switch, the uncharged single batteries are selected to continue charging; during the discharging process, the completely discharged single batteries and the incompletely discharged single batteries are judged according to the corresponding state of charge, and by controlling the corresponding first switch and second switch, the incompletely discharged single batteries are selected to continue discharging.

[0144] In a battery string, due to its own characteristics (such as internal resistance difference, initial charge difference, etc.), the voltages of different single batteries may be different. In one embodiment, in order to determine whether a single battery 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 battery is lower than the charging threshold voltage V_ch (i.e., V_i < V_ch), it means that the charge of this single battery is low and a charging operation is still required; if the sampled voltage V_i of a certain single battery is higher than the discharging threshold voltage V_dis (i.e., V_i > V_dis), it means that the charge of this single battery is high and a discharging operation is required.

[0145] For the single battery that needs to be charged, control the corresponding first switch and second switch to conduct, so that the current output by the charge and discharge module can flow into this single battery and charge it.

[0146] For the single battery that needs to be discharged, also control the corresponding first switch and second switch to conduct. At this time, the charge and discharge module can control this single battery to discharge and release its excess charge.

[0147] In addition, when the entire battery string is in the 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 corresponding first switch and second switch of this single battery to disconnect and stop charging it to avoid overcharging. Similarly, when the entire battery string is in the discharging state, if the sampled voltage of a certain single battery has reached the discharging threshold voltage, it is also necessary to control its corresponding switch to disconnect to prevent over-discharging.

[0148] In one embodiment, during the charge and discharge process, the voltage of the single cell will continuously change. Therefore, it is necessary to monitor the sampled voltage and sampled current in real time and dynamically adjust the conduction states of the first switch and the second switch corresponding to each single cell. For example, when charging a certain single cell, as its charge increases, the sampled voltage will gradually rise. When the sampled voltage reaches the charging threshold voltage, the first switch and the second switch corresponding to this single cell are timely controlled to disconnect and the charging is stopped. On the contrary, during the discharge process, when the sampled voltage drops to the discharge threshold voltage, the switch is controlled to disconnect and the discharge is stopped.

[0149] In one embodiment, through the comprehensive control of the conduction states of the first switch and the second switch according to the sampled voltage and the sampled current, the single cells in the battery string that meet the charge and discharge requirements are respectively charged and discharged, thus solving the problem of incomplete charge and discharge of each single cell in the battery string and achieving the purpose of balanced charge and discharge of the battery string.

[0150] In one embodiment, as Figure 33 shown, the conduction states of the first switch and the second switch corresponding to the respective single cells are respectively controlled according to the sampled voltage and the sampled current to select and charge and discharge the single cells that meet the charge and discharge requirements, which specifically includes:

[0151] Step 201: In the charging state, judge whether the state of charge of each single cell is in the fully charged state or in the not fully charged state according to the sampled voltage and the sampled current.

[0152] During the charging process, the system continuously obtains the sampled voltage and sampled current of each single cell. To judge whether the battery is fully charged, a clear standard is needed. 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.

[0153] In one embodiment, after a certain single cell enters the constant voltage charging mode, the charging current is adjusted to keep the voltage at Va all the time. As the single cell is gradually fully charged, the current used to maintain this single cell gradually decreases. When the corresponding sampled current drops to Ia, it means that this single cell is fully charged, and vice versa for not fully charged. Among them, when the battery charging reaches the maximum charging voltage (the current maximum charging voltage of the used battery is 3.65V), then 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 34As shown, when the temperature is 10°C and the battery charge of a single cell is between 0 and 80%, the maximum charging current is 0.5C. For example, if the current single cell capacity is 50AH, a charging current of 0.5C represents 50AH * 0.5C = 25A. That is, the maximum current that can be used to charge this single cell currently is 25A. By analogy, the maximum charging current of each battery can be obtained.

[0154] When the maximum charging current is determined according to the above method and used for charging, if the voltage of a certain single cell is obtained to exceed 3.65V, the charging current is reduced. At the same time, the sampled voltage of this single cell will also decrease as the charging current decreases. If it is found that the sampled voltage of the single cell that has reached 3.65V is lower than 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 each increase or decrease of the charging current 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.

[0155] In one embodiment, the system determines the state of charge of the battery based on the sampled voltage and current and combines the characteristics of the battery to determine whether the single cell is fully charged. For example, if the sampled 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 determined 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 an uncharged state.

[0156] Step 202: Disconnect the first switch and the second switch at both ends of the first single cell in the fully charged state, conduct the first switch and the second switch at both ends of the second single cell in the uncharged state, and control the charge and discharge module to charge the second single cell until it is detected that the state of charge of the second single cell reaches the fully charged state.

[0157] Alternatively, obtain the connection relationship of the second single cells in the uncharged 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.

[0158] Among them, overcharging will damage the single battery and shorten its service life. For the first single battery determined to be fully charged, 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 single battery, avoiding overcharging. In one embodiment, during the charging process, when it is determined that multiple single batteries are fully charged, the corresponding first switch and second switch of each of them are disconnected respectively.

[0159] For the second single battery in an uncharged state, since there are fully charged single batteries in the battery string, the original charging circuit is no longer conducting. Therefore, the system will control the first switch and the second switch at both ends of it to conduct. After conducting the corresponding switch, the charge and discharge module and these uncharged batteries form a complete charging circuit, and current can flow from the charge and discharge module to one or more second single batteries to continue charging the second single battery. During the process of continuing to charge one or more second single batteries, the system will continuously monitor the voltage and current changes of each second single battery. As the charging progresses, the sampled voltage of the second single 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 single 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.

[0160] During the charging process, the system will also dynamically adjust the charging current according to the state of the single battery. In 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 single battery) can be used for fast charging. As the power level of the single battery increases, the charging current will gradually decrease to prevent the battery from overheating and overcharging. When it is detected that the single 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.

[0161] In one embodiment, as Figure 35 shown, the method of respectively controlling the conduction states of the first switch and the second switch corresponding to the corresponding single battery according to the sampled voltage and the sampled current to select to charge and discharge the single batteries meeting the charge and discharge requirements respectively further includes:

[0162] Step 301: In the discharge 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.

[0163] 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 battery. These information change in real time and reflect the current discharge state of the single battery. 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 battery drops to a specific lower limit value (such as 2.5V - 3.0V), it is usually considered that the battery is in the fully discharged state. Because if continuous over-discharge occurs, it will cause irreversible damage to the internal structure of the battery, reducing the performance and lifespan of the battery.

[0164] If the sampled voltage of a certain single battery has dropped to the above-mentioned lower limit value, or it is found through analysis of the current situation that the single battery can no longer provide effective electrical energy output, then it is determined that the single battery is in the 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 indicates that there is still remaining charge in the single battery and it is in the not fully discharged state.

[0165] Step 302: Disconnect the first switch and the second switch at both ends of the third single battery in the fully discharged state, conduct the first switch and the second switch at both ends of the fourth single battery in the not fully 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.

[0166] Or, obtain the connection relationship of the second single battery in the not fully discharged state. If there are at least two second single batteries forming a series relationship, then form a series battery pack with at least two second single batteries, and conduct the first switch corresponding to the series battery pack and the second switch corresponding to the series battery pack.

[0167] In one embodiment, when it is determined that a certain third single battery 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 battery, preventing current from continuing to flow out of the corresponding third single battery and avoiding the occurrence of over-discharge.

[0168] For the fourth single battery in the not fully discharged state, the system controls the corresponding first switch and second switch to conduct. In this way, a closed discharge loop is formed between the charge and discharge module and the corresponding one or more fourth single batteries, and the electrical energy in the corresponding fourth single battery can be output through the charge and discharge module to supply power to external devices. During this process, the charge and discharge module will reasonably adjust the magnitude of the discharge current according to the requirements of external devices.

[0169] It should be noted that during the discharge process of the fourth single-cell battery, the system continuously monitors the changes in its sampled voltage and sampled current. As the discharge progresses, the sampled voltage gradually decreases, and the sampled current also changes according to the variation of the external load. When the system detects that the sampled voltage of the corresponding fourth single-cell battery drops to the standard value of full discharge, or determines based on the current change that the battery can no longer effectively discharge, it controls the first switch and the second switch at both ends of the fourth single-cell battery to disconnect and stop the discharge. This ensures that each single-cell battery can discharge within a safe range and avoids damage to the battery caused by over-discharge.

[0170] In summary, during the entire discharge process, the system uniformly manages all single-cell batteries, pays real-time attention to the state changes of each single-cell battery, and dynamically adjusts 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 battery can be made as uniform as possible, improving the overall performance and service life of the battery string.

[0171] The state of charge of a single-cell battery has a significant impact on its maximum discharge current. When a single-cell battery is in a relatively high state of charge, it can generally withstand a relatively large discharge current; while when the state of charge is low, the internal resistance of the battery increases. At this time, if it discharges with a large current, excessive heat will be generated, which may damage the battery. For example, when the SOC (full English name: State of Charge) of a single-cell battery is 80%, it can safely discharge at a current of 3C; but 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 battery slows down, and the ion conduction ability decreases. At this time, the maximum discharge current of the single-cell battery is limited. For example, in an environment of -20°C, the original maximum discharge current of a certain single-cell battery of 3C may need to be reduced to 1C or even lower to prevent problems such as lithium plating inside the battery from affecting the battery performance and safety. As the number of battery usage increases, the electrode materials inside the battery 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-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 battery 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 of the maximum discharge currents.

[0172] In one embodiment, as Figure 36As shown, when each single cell leaves the factory, the manufacturer will provide a detailed specification sheet, which clearly marks the maximum discharge current that the cell 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 operating conditions and combining with the equivalent circuit model of the battery, the maximum discharge current that the battery can withstand under the current state can be deduced.

[0173] After evaluating the maximum discharge current of each single cell, the minimum value is selected from the maximum discharge current values of all single cells. For example, referring to Figure 36 , if 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.

[0174] As the discharge progresses, parameters such as the state of charge and temperature of each single cell will change continuously, and the maximum discharge current of each single cell may also change. For example, during the discharge process, if the temperature of a single cell increases, its maximum discharge current may decrease. At this time, it is necessary to re-evaluate the maximum discharge current of each single cell, determine the new minimum value, and accordingly adjust the discharge current of the charge and discharge module to ensure that the entire battery string always operates under safe conditions.

[0175] 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 and discharge module in this embodiment charges the battery string). Under the premise that the electrical energy transmitted by the photovoltaic module cannot fully charge each single cell in the battery string in a cloudy day with insufficient light or a dark external environment at night, the method for controlling the balanced charge and discharge of the battery string further includes: when the charge and discharge module can only support charging the remaining single cell, select the single cell with the lowest voltage for charging according to a preset period to continuously increase the power of the single cell with the lowest voltage and reduce the voltage difference between each single cell.

[0176] Taking a photovoltaic system as an example, photovoltaic modules convert light energy into electrical energy during the day to charge the battery string. However, on cloudy days with low light intensity or at night without light, the electrical energy generated by the photovoltaic modules 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 and discharge module and the charging requirements of the battery string in real time. When it is found that the power output by the charge and discharge module is only enough to charge the remaining single battery, the subsequent equalization charging strategy will be triggered. For example, a photovoltaic system is equipped with a charge and 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 and discharge module can only support charging a single battery.

[0177] To reduce the voltage difference between single batteries, 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, the screening is carried out once every 30 minutes. Each time the 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.

[0178] After determining the single battery with the lowest voltage, the system will control the first switch and the second switch corresponding to this single battery to make the charge and discharge module charge only this single battery. During the charging process, the system will continuously monitor the voltage change of this single battery. When the charging reaches a certain duration or the voltage of the single battery rises to the set threshold, the charging will be paused. Then, entering the next preset period, the system will screen out the single battery with the lowest voltage again for charging. For example, the initial voltage of the selected single battery is 3.1V, and the charging threshold is set at 3.5V. When the voltage of this single battery reaches 3.5V, the charging is paused. In the next 30 - minute period, the single battery with the lowest voltage is screened again. Maybe at this time, another single battery has the lowest voltage, and it will be charged.

[0179] By continuously selecting the single battery with the lowest voltage for charging according to the preset period, each charge will increase the power of this single battery and thus increase its voltage. Over time, the voltage difference between single batteries will gradually decrease, improving the overall performance of the battery string.

[0180] In a series-connected battery string, if the voltages of some individual battery cells are too high and those of some are too low, the performance of each individual battery cell will be inconsistent, thus affecting the use of the entire battery string. When the charging and discharging module completely stops generating electrical energy, that is, in the above example, the photovoltaic module fails and cannot continue to charge the battery string. To ensure that the battery maintains the smallest voltage difference between individual battery cells and the stability of the battery string when the photovoltaic module fails, in one embodiment, an energy storage module is provided between each first switch and the positive electrode of the corresponding individual battery cell. Each energy storage module is equipped with a corresponding control switch, and the energy storage module includes an energy storage unit.

[0181] As Figure 37 shown, the method for controlling the balanced charging and discharging of the battery string further includes:

[0182] Step 401: When the charging and discharging module cannot support charging the remaining individual battery cells that are not fully charged, turn off the charging and discharging module, and obtain the state of charge of each individual battery cell based on the sampled voltage and the sampled current respectively.

[0183] During the charging process, the system will monitor the output capacity of the charging and discharging module in real time. When the charging and discharging module cannot continue to provide sufficient charging current for the remaining individual battery cells that are not fully charged due to its own power limitation, failure, insufficient power, etc., the system will make a judgment and turn off the charging and discharging module. For example, a charging and discharging 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 individual battery cells require 50W of power to charge normally. In this case, it is determined that the charging and discharging module cannot support charging and it is turned off.

[0184] After turning off the charging and discharging module, the system will calculate the state of charge of each individual battery cell based on the sampled current of each individual battery cell collected. Specifically, the state of charge of the individual battery cell at each moment is calculated through the following formula:

[0185]

[0186] where Q is the integral value (i.e., the charge that has been charged into the individual battery 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 to accurately obtain the state of charge of each individual battery cell at each moment, it is necessary to ensure that the state of charge of each individual battery cell is 0 (i.e., in a fully discharged state) at the start of charging.

[0187] Step 402: Compare the state of charge of adjacent single cells, and control the conduction states of the first switch, the second switch, and the control switches of the corresponding energy storage modules, so that the single cell with a larger state of charge charges the corresponding energy storage unit.

[0188] Among them, after obtaining the state of charge of each single cell, the system will compare the state of charge of two adjacent single cells one by one. For example, in a battery string composed of 10 series-connected single cells, 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.

[0189] 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, as Figure 38 shown, through the above detection process, at a certain detection node, the state of charge of single cell A is greater than that of single cell B. Therefore, turn on the first switch Sa1 corresponding to single cell A, the first switch Sb1 corresponding to single cell B, the control switch Ka2, and the control switch Kb1 of the corresponding energy storage unit LB, and turn off the second switch Sa2 of single cell A, so that single cell A and the corresponding energy storage unit LB form a charging circuit, so that single cell A charges the energy storage unit LB.

[0190] Step 403: After charging the energy storage unit for a preset time, control the conduction states of the first switch, the second switch, and the control switches of the corresponding energy storage unit, so that the charged energy storage unit charges the single cell with a smaller state of charge.

[0191] Among them, still taking the above example, the system will preset a charging time for 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.

[0192] In one embodiment, referring to Figure 38 , when single cell A charges the energy storage unit LB to the preset time, the system will re-control the conduction state of the switch. At this time, turn off the first switch Sa1, turn off the second switch Sb2 corresponding to single cell B, turn on the first switch Sb1 corresponding to single cell B, the first switch Sc1 corresponding to single cell C, and the control switch Kc2 on the energy storage unit LC, so that the charged energy storage unit LB and single cell B form a charging circuit, so that the energy storage unit LB charges single cell B.

[0193] Through the above steps, when the charging and discharging module cannot support charging, the energy storage module realizes the equalization of the power between adjacent single cells, improving the overall performance and service life of the battery string.

[0194] In summary, in this embodiment, the sampling voltages at both ends of each single cell and the sampling current in the charging and discharging loop of the battery string are obtained; then, according to the sampling voltage and the sampling current, the conduction states of the first switch and the second switch corresponding to the respective single cells are controlled respectively to select to charge and discharge the single cells that meet the charging and discharging requirements; it is possible to charge and discharge a single single cell individually, and finally achieve the full charge and full discharge of each single cell; it solves the limitation that in an energy storage battery system, only one or a very small number of single cells can be fully utilized; it is possible to charge and discharge a single single cell, or multiple single cells can be charged and discharged together; it solves the problem of unbalanced charging and discharging of the battery system, thereby maximizing the utilization of battery resources.

[0195] Embodiment 3:

[0196] Based on Embodiment 1 and Embodiment 2, in the battery string assembly structure proposed in Embodiment 1, a contact resistance is generated between an adjacent single cell by a battery conductive structure and a corresponding external conductive structure. During the actual installation of the battery string, it may cause poor contact between the single cells, resulting in too large a contact resistance of the single cells, wasting charging and discharging energy, and affecting the evaluation of the power of the single cells in Embodiment 2, causing a single cell to be judged as full when it is far from being full and judged as discharged when it is far from being emptied. 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.

[0197] Therefore, in order to prevent the contact resistance from affecting the feasibility of the method for controlling the balanced charging and discharging of the battery string proposed in this embodiment (that is, the contact resistance affects the sampling voltage, and the influence on the sampling 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, this embodiment provides a method for self-checking the contact resistance of a battery string, including: before the charging and discharging process of the battery string, detecting the contact resistance of each single cell in the battery string, specifically including:

[0198] Step 501: Obtain the open-circuit voltage of each single cell in the battery string in the open-circuit state.

[0199] Among them, before performing charge and discharge operations on the battery string, the system first sets the battery string to an open circuit state, that is, disconnects all connections to external loads and charge and discharge devices. Using a high-precision voltage sensor, the open circuit voltages at both ends of the positive and negative electrodes of each single battery are collected. The open circuit voltage can reflect the potential difference of the single battery when no current passes through. Taking a battery string composed of three single batteries connected in series as an example, a professional voltage measurement device is used to measure the open circuit voltage of each single battery one by one and record the data. For example, the open circuit voltages of the three single batteries are V_10 = 3.2V, V_20 = 3.18V, and V_30 = 3.22V in sequence.

[0200] Step 502: Output a short-term constant current through a constant current source to charge the battery string, and obtain the collected voltage at both ends of each single battery during the charging process.

[0201] A specific short-term constant current is output to the battery string by the constant current source. The magnitude and duration of the short-term 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 at both ends of each single battery as the collected voltage. Still taking the battery string composed of the above three single batteries as an example, assuming that the current I output by the constant current source is 1A and the duration is 0.5 seconds. Within this 0.5 seconds, the system measures the collected voltage at both ends of each single battery through the voltage sensor, which are V_1 = 3.25V, V_2 = 3.23V, and V_3 = 3.27V respectively.

[0202] Step 503: Obtain the contact resistance of the corresponding single battery according to the open circuit voltage, the short-term constant current, and the collected voltage.

[0203] 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-term constant current output by the constant current source.

[0204] Taking the first single battery as an example, the calculation process of its contact resistance Rc1 is as follows:

[0205] △V = V_1 - V_10 = 3.25V - 3.2V = 0.05V. According to Ohm's law, Rc1 = △V / I = 0.05V / 1A = 0.05Ω; similarly, the contact resistances of other single batteries can be calculated.

[0206] Through the above steps, the system can detect the contact resistance of each single cell before the charging and discharging of the battery string. Once it is found that the contact resistance of a certain single cell exceeds the normal range, measures can be taken in a timely manner, such as rechecking 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 cell due to the contact resistance problem.

[0207] In one embodiment, after obtaining the contact resistance of each single cell in the above manner, the method for self-checking the contact resistance of the battery string 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; where, Vc is the sampling voltage, Vm is the voltage value actually collected at both ends of each single cell, Ic is the sampling current, and Rc is the contact resistance corresponding to the corresponding single cell.

[0208] During the actual charging and discharging process of the battery string, the existence of the contact resistance will affect the measurement of the voltage at both ends of the single cell. In order to obtain a more accurate sampling voltage, it is necessary to correct the actually collected voltage value based on the detected contact resistance. The calculation methods of the sampling voltage will be introduced separately from the charging and discharging processes below.

[0209] During the charging process, the current flows from the charging source into the battery string, and the contact resistance will cause voltage loss. At this time, for example, when charging the battery string composed of the three single cells mentioned above, the voltage value Vm1 actually collected at both ends of the first single cell is 3.5V, the sampling current Ic = 0.8A, and through the previous detection, it is known that the contact resistance Rc1 of the first single cell is 0.05Ω. Substituting 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 sampling voltage of the first single cell is 3.46V. For other single cells, the same method is also used, substituting their respective corresponding Vm, Ic, and Rc values to calculate the accurate sampling voltage.

[0210] During the discharging process, 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 single cells as an example: the actually measured voltage value Vm2 across the second single cell is 3.0V, the sampling current Ic = 0.6A, and the contact resistance R_c2 of the second single cell is 0.05Ω. Substitute the above data into the formula: Vc = 3.0V + 0.6A * 0.05Ω = 3.03V. This indicates that considering the contact resistance, the voltage has increased by 0.03V, and the true sampled voltage of the second single cell is 3.03V. By analogy, similar calculations are performed on the remaining single cells to obtain accurate sampled voltages.

[0211] 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 single cell 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.

[0212] In this embodiment, the open-circuit voltage across each single cell in the battery string in the open-circuit state is obtained; and a short-term constant current is output by a constant current source to charge the battery string, and the sampled voltage across each single cell is obtained during the charging process; finally, the contact resistance of the corresponding single cell is obtained according to the open-circuit voltage, the short-term constant current, and the sampled voltage. By passing a short-term constant current through the battery string to cause a voltage drop due to the contact resistance for each single cell, the problem of too high contact resistance caused by operation during the assembly of the battery string can be detected, and it can be automatically determined whether the single cell is correctly installed. The entire system has a simple structure, easy detection operation, and can flexibly control different detection nodes to automatically detect the contact resistance of different single cells.

[0213] Embodiment 4:

[0214] To further illustrate the foregoing embodiments, this embodiment proposes a circuit for controlling the balanced charge and discharge of a 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.

[0215] 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 circuit of the battery string for charge and discharge; 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.

[0216] Among them, the entire circuit is built with the goal of controlling the battery string to achieve balanced charge and discharge, 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 is connected to the negative electrode of the battery string, 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 (English full name: 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).

[0217] 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 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.

[0218] 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.

[0219] During the charging stage, the control module comprehensively analyzes the sampled voltages of each single battery. For a single battery with a low sampled voltage 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 it. As the charging progresses, the voltage sampling module continuously monitors the voltage change of the single battery. 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.

[0220] 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.

[0221] 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.

[0222] In one embodiment, referring to Figure 41 and Figure 42, when only the single battery 1 is detected to be fully charged (or discharged), the sub-battery string composed of the single battery 2, the single battery 3, and the single battery 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.

[0223] 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.

[0224] In one embodiment, the discharge stage is the same as the charging stage. The control module will pay attention to the single battery with a higher state of charge and control the conduction of its corresponding switch to 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 battery drops to a certain level, the control module will control the corresponding first switch and second switch to disconnect to prevent over-discharge.

[0225] Through the above method, throughout the entire process of charge and discharge, it is ensured that each single battery 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.

[0226] Referring to the foregoing embodiments, in a series-connected battery string, if some single batteries have too high a voltage and some single batteries have too low a voltage, the performance of each single battery 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 the photovoltaic module fails or does not generate electricity and cannot continue to charge the battery string, in order to ensure that the battery string maintains the smallest voltage difference between each single battery 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 the single battery 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. 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. It should be noted that an energy storage module can be arranged between the positive electrode of the first single battery and the last single battery and its corresponding first switch, or it can be not arranged. 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 PWM signal output by the control module.

[0227] Among them, when the charge and discharge module fails or does not generate 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.

[0228] 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.

[0229] 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 and 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.

[0230] 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.

[0231] 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.

[0232] 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 are respectively connected to the positive electrode and the negative electrode of a certain single battery to supply power to the entire integrated circuit board. Among them, the control module is independently powered.

[0233] 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, both the third control switch and the fourth control switch are MOS transistors controlled by the PWM signal output by the control module.

[0234] 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, in order 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.

[0235] 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 corresponding third control switch and fourth control switch at both ends of the single battery are selected to conduct, so as to supply power to the integrated circuit board through the single battery.

[0236] 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.

[0237] 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 unit is connected in parallel with each single cell, the voltage mapping unit is 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, and the control module is also connected to the multiplexer.

[0238] 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, and 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.

[0239] 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 its 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, a zener diode D1 is used to protect the gate-source voltage to prevent the field effect transistor Qs from being damaged.

[0240] 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, and 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:

[0241] VSAMPi = Vin i+ -Vin i- -I × (Rmosi + RLia), i ≠ 1, i ≠ N;

[0242] Among them, VSAMPi represents the voltage across the i-th single cell, Vin+ represents the positive voltage of the i-th single cell, Vin- represents the negative voltage of the i-th single 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.

[0243] For the single cells located at both ends of the battery string, the current in a set of cable parasitic impedances in their circuits cannot be cancelled out with adjacent single cells. Therefore, the expression for the sampled voltage is as follows:

[0244] VSAMPi = Vin i+ -Vin i- -I×(Rx + Rmosi + RLia), i = 1, i = N;

[0245] Among them, VSAMPi represents the voltage across the i-th single cell, Vin+ represents the positive voltage of the i-th single cell, Vin- represents the negative voltage of the i-th single 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.

[0246] According to the above method, the voltage across each single 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 cell to determine the state of charge of the single cell. The contact resistance of the single cell also needs to be considered. For details, refer to the above embodiments, which will not be elaborated in this embodiment.

[0247] Embodiment 5:

[0248] In this embodiment, a self-checking device for the contact resistance of a battery string is proposed. As Figure 49 shown, it is used to implement the self-checking method for the contact resistance of the battery string as described in Embodiment 3, including: a first acquisition module, a second acquisition module, and a third acquisition module; the first acquisition module is used to acquire the open-circuit voltage across each single cell in the battery string in the open-circuit state; the second acquisition module is used to output a short-term constant current through a constant current source to charge the battery string and acquire the acquired voltage across each single cell during the charging process; the third acquisition module is used to obtain the contact resistance of the corresponding single cell according to the open-circuit voltage, the short-term constant current, and the acquired voltage.

[0249] Among them, for the specific process of the self-checking method for the contact resistance of the battery string, refer to Embodiment 3, which will not be elaborated in this embodiment.

[0250] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for self-checking the contact resistance of a battery string, characterized in that, Including: Obtaining the open-circuit voltage across each single cell in the battery string in the open-circuit state; Outputting a short-term constant current through a constant-current current source to charge the battery string, and obtaining the collected voltage across each single cell during the charging process; Obtaining the contact resistance of the corresponding single cell based on the open-circuit voltage, the short-term constant current, and the collected voltage.

2. The method for self-checking the contact resistance of a battery string according to claim 1, wherein, The self-checking method for the contact resistance of the battery string is applied to the battery string. The battery string includes batteries and a battery-string assembly structure. The battery (3) is disposed in the battery-string assembly structure. The contact resistance is generated by the connecting conductive components in the battery-string assembly structure. The battery-string assembly structure 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 the battery (3) and making direct contact with the positive or negative electrode of the battery (3); Each connecting conductive component (2) is further used for connecting an external circuit (4) to realize the coupling between the battery (3) and the external circuit (4).

3. The method for self-checking the contact resistance of a battery string according to claim 2, characterized in that, The connecting conductive component (2) includes a connecting component (21), a battery conductive structure (22), and an external conductive structure (23) formed by extending from the battery conductive structure (22); The battery conductive structure (22) is mounted on the connecting component (21), and the connecting component (21) is connected in series on the series connection rod (1); The battery conductive structure (22) makes direct contact with the positive or negative electrode of the battery (3); The external conductive structure (23) is used for connecting the external circuit (4) to realize the coupling between the battery (3) and the external circuit (4).

4. The method for self-checking the contact resistance of a battery string according to claim 2, wherein, The connecting component (21) includes a connecting piece (211) and a fixing ring (212); At least one inserting piece (2110) is provided at at least one end of the connecting piece (211); at least one slot (2120) is provided on the ring wall of the fixing ring (212), and the slot (2120) matches the inserting piece (2110); The inserting piece (2110) is inserted into the slot (2120) to mount the connecting piece (211) inside the ring of the fixing ring (212) and make the connecting piece (211) perpendicular to the axis of the fixing ring (212); At least one protruding portion (2121) is provided on the outer wall of the fixing ring (212), and a channel (21210) parallel to the axis of the fixing ring (212) is provided on the protruding portion (2121). The series connection rod (1) is inserted into the channel (21210) to connect the connecting component (21) in series; The connecting piece (211) is used for providing an installation position for the battery conductive structure (22).

5. The method for self-checking the contact resistance of a battery string according to claim 4, wherein The battery conductive structure (22) includes a first conductive piece (221) and a second conductive piece (222) arranged oppositely, and a first connecting portion (223) connecting the first conductive piece (221) and the second conductive piece (222); A placing groove (2111) matching the first connecting portion (223) is provided on the connecting piece (211); One side of the placement groove (2111) is provided with an opening (2112), and the opening (2112) penetrates through to the edge of the connecting piece (211), so that the first connecting portion (223) is placed in the placement groove (2111) through the opening (2112), and the first conductive sheet (221) is located on the first connecting surface of the connecting piece (211), and the second conductive sheet (222) is located on the second connecting surface of the connecting piece (211); wherein, the first connecting surface and the second connecting surface are two opposite connecting surfaces of the connecting piece (211); The first conductive sheet (221) is in direct contact with the battery (3) on the side where the first connecting surface is located; The second conductive sheet (222) is in direct contact with the battery (3) on the side where the second connecting surface is located.

6. The method for self-checking the contact resistance of a battery string according to claim 4, wherein The external conductive structure (23) is a connecting pipe; The connecting pipe is used for inserting an external circuit (4) therein to realize connection with the external circuit (4).

7. The method for self-checking the contact resistance of a battery string according to claim 4, wherein The outer wall of the fixing ring (212) is provided with a buckle (2122); the connecting pipe is inserted into the buckle (2122) to realize the fixation of the connecting pipe.

8. The method for self-checking the contact resistance of a battery string according to claim 4, wherein The protruding portion (2121) includes a first sub-protruding portion (21211) and a second sub-protruding portion (21212); The pore channel (21210) includes a first sub-pore channel (212101) provided on the first sub-protruding portion (21211) and a second sub-pore channel (212102) provided on the second sub-protruding portion (21212); The first sub-protruding portion (21211) and the second sub-protruding portion (21212) are oppositely arranged, and the first sub-pore channel (212101) and the second sub-pore channel (212102) are oppositely arranged; A gap is provided between the first sub-protruding portion (21211) and the second sub-protruding portion (21212) to form the slot (2120); The insertion piece (2110) is provided with a first through hole (21101) at a position aligned with the first sub-pore channel (212101) and the second sub-pore channel (212102), so that the series connection rod (1) passes through the first through hole (21101) when inserted into the pore channel (21210).

9. The method for self-checking the contact resistance of a battery string according to claim 1, wherein, The method further includes: During the charging process of the battery string, the calculation method of the sampling voltage at both ends of each single battery in the battery string is: Vc = Vm - Ic * Rc; During the discharging process of the battery string, 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 at both ends of each single battery, Ic is the sampling current, and Rc is the contact resistance corresponding to the corresponding single battery.

10. A self-checking device for the contact resistance of a battery string, characterized in that, For implementing the battery string contact resistance self-checking method according to any one of claims 1-9, including: a first acquisition module, a second acquisition module, and a third acquisition module; The first acquisition module is used for acquiring the open-circuit voltage at both ends of each single battery in the battery string in the open-circuit state; The second acquisition module is configured to output a short-term constant current through a constant current source to charge the battery string, and acquire the collected voltage across each single battery during the charging process; The third acquisition module is configured to obtain the contact resistance of the corresponding single battery according to the open-circuit voltage, the short-term constant current, and the collected voltage.

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