Lithium battery BMS active equalization system and equalization method thereof

Abstract

The invention discloses a lithium battery BMS active equalization system which comprises a lithium battery power supply module, a lithium battery equalization module, a control management box and an integration box of a power supply circuit and an equalization energy circuit. The lithium battery power supply module comprises an A-type lithium battery pack and a B-type lithium battery pack; the lithium battery equalization module comprises two equalization lithium batteries; a microcontroller and a BMS communication module are arranged in the control management box; an upper layered plate and a lower layered plate are arranged in the integration box of the power supply circuit and the energy equalization circuit, the power supply circuit is arranged in the upper layer of the integration box of the power supply circuit and the energy equalization circuit, and an equalization and charging circuit is arranged in the lower layer of the integration box of the power supply circuit and the energy equalization circuit. And the equalization battery performs equalization charging. According to the invention, the electric quantity of the battery and the power supply demand can be accurately judged, rapid equalizing charging of the lithium battery with low electric quantity is ensured, a new lithium battery with low electric quantity is replaced for power supply, the equalizing charging replacement speed is high, and the equalizing charging efficiency is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium battery balancing, and in particular to a lithium battery BMS active balancing system and a balancing method thereof. Background Art

[0002] Currently, there are three main types of active balancing solutions for lithium batteries commonly used on the market: capacitive balancing, inductive balancing, and transformer balancing. All three balancing methods can achieve equalization during charging and during static balancing, but they all employ a method of shifting energy from high-capacity cells to low-capacity cells through external circuitry to achieve a uniform charge level. These balancing solutions have the following drawbacks: 1. Capacitive and inductive balancing only transfer energy between adjacent cells. When only a few cells in a battery pack have high or low capacity, the capacity of all cells must be adjusted, resulting in low balancing efficiency. 2. Transformer balancing can transfer energy between non-adjacent cells, but extracting energy from high-capacity cells is equivalent to additional discharge, which increases the relative aging rate of the cells and accelerates the cycle life of high-capacity cells. The balancing process also results in significant energy loss, making it unsuitable for lithium battery power. The balancing process cannot precisely determine the balancing solution for each lithium battery, resulting in the battery still not meeting power requirements or maintaining significant capacity differences between cells after balancing. Summary of the Invention

[0003] The present invention aims to at least partially address one of the technical problems in the related art. To this end, one object of the present invention is to provide a lithium battery BMS active balancing system and balancing method thereof, which solves the problems of low balancing efficiency, high energy loss during the balancing process, and poor balancing.

[0004] According to the present invention, a lithium battery BMS active balancing system includes a lithium battery power supply module, a lithium battery balancing module, a control management box, and an integrated box of a power supply circuit and a balancing energy circuit;

[0005] The lithium battery power supply module includes two groups of type A lithium battery groups and one group of type B lithium battery groups. The number of lithium batteries in each of the type A lithium battery group and the type B lithium battery group is four and the lithium battery model is the same. The three groups of lithium battery groups are arranged in a row, and the tabs on the top of the lithium battery are arranged on the same straight line near the right edge. The two positive and negative tabs on the top of each lithium battery have the same structure. The tabs include tab posts, upper extended copper bars, and lower extended copper bars.

[0006] The lithium battery balancing module includes two balancing lithium batteries, and two balancing power supply tabs are provided on the right side of the top of the two balancing lithium batteries;

[0007] The control management box is provided with a microcontroller and a BMS communication module, and the microcontroller is electrically connected to the BMS communication module;

[0008] The integrated box of the power supply circuit and the energy balancing circuit is provided with an upper and lower layered board, wherein the upper layer of the integrated box of the power supply circuit and the energy balancing circuit has a power supply circuit, and the lower layer has a balancing and charging circuit;

[0009] The power supply circuit includes two power supply wires, a plurality of first electrically controlled double-cut switches, and a plurality of first electrically controlled single-cut switches. The two power supply wires are arranged in parallel and connected by a wire at the same end, and the other end is an output end. The first power supply wire is parallel to the tabs on the top of all lithium batteries in a straight line. The upper extended copper busbar on the positive and negative tabs of each lithium battery is respectively connected to two interfaces at the input end of a first electrically controlled double-cut switch. The two output wires at the output end of the first electrically controlled double-cut switch are connected to two points on the first power supply wire, and the power supply wire between the two points is connected to the first electrically controlled single-cut switch.

[0010] The balancing and charging circuit includes an input balancing circuit and three identical output balancing circuits. The input balancing circuit includes a DC / AC converter, a loop conductor, and three sets of transformer positive windings. The two interfaces at the output end of the DC / AC converter are electrically connected by the two ends of the loop conductor. Three electrically controlled balancing start switches are evenly spaced on the loop conductor. On each loop conductor at the position of the electrically controlled balancing start switch, a transformer positive winding is connected in parallel on both sides of the electrically controlled balancing start switch. An electrically controlled series start switch is provided at the input end of the transformer positive winding. The loop conductor is connected to two external charging wires at the output end of the DC / AC converter. The output balancing circuit includes an AC / DC converter, a transformer secondary winding, and four second electrically controlled double-cut switches. The two input ends of the AC / DC converter are respectively connected to a transformer secondary winding and an extension wire. The transformer secondary winding is parallel to a corresponding transformer positive winding. A switching wire electrically connected to the extension wire is provided at the middle position and the tail position of the transformer secondary winding. Both switching wires are provided with a first voltage conversion electrically controlled single-cut switch and a second voltage conversion electrically controlled single-cut switch. The output end of the AC / DC converter will be provided with two balancing wires. The input ends of the four second electrically controlled double-cut switches are connected in series in parallel to the two balancing wires. Each output balancing circuit corresponds to a lithium battery pack, and the output ends of the four second electrically controlled double-cut switches on the output balancing circuit are respectively electrically connected to the lower extended copper busbars of the four lithium batteries in a lithium battery pack.

[0011] Each of the two balancing power supply lugs on the top of the two balancing lithium batteries has a charging wire. The two charging wires on the two balancing power supply lugs on the top of one of the balancing lithium batteries are provided with a first charging single-cutoff switch, and the two charging wires on the two balancing power supply lugs on the top of the other balancing lithium battery are provided with a second charging single-cutoff switch. A third charging single-cutoff switch is provided on the wires electrically connected between the two closest positive balancing power supply lugs and the negative balancing power supply lugs on the top of the two balancing lithium batteries. The charging wires on the two balancing power supply lugs on the top of the two balancing lithium batteries are respectively connected to the input terminals of the DC / AC converter.

[0012] The BMS communication module is used to obtain voltage information and power information of each lithium battery in the three groups of lithium batteries, and the microcontroller is used to control all electronically controlled double-cut switches and electronically controlled single-cut switches on the power supply circuit, the balancing and charging circuit, and the balancing lithium battery output circuit.

[0013] In some embodiments of the present invention, the two groups of type A lithium battery packs are priority power supply lithium battery packs, and the type B lithium battery pack is a balanced replacement lithium battery pack. When the power supply voltage requirements are met, it is necessary to ensure that the power of each lithium battery is above 50% and at least eight lithium batteries are required.

[0014] In some other embodiments of the present invention, the two balancing lithium batteries are of the same model, and the battery capacity of the balancing lithium battery is 2-3 times the capacity of one lithium battery.

[0015] In other embodiments of the present invention, an insulating pad is inserted between the lithium battery power supply module, the lithium battery balancing module and the control management box. The lithium battery balancing module is flush with the top of the control management box and an insulating pad is also inserted between the lithium battery balancing module and the integrated box of the balancing energy circuit.

[0016] A lithium battery BMS active balancing method uses the above-mentioned lithium battery BMS active balancing system to achieve balancing. The specific balancing steps are as follows:

[0017] S1: When two groups of type A lithium battery packs and one group of type B lithium battery packs are fully charged, the two groups of type A lithium battery packs are started first to supply power, the first electrically controlled double-cut switches corresponding to the extended copper bars on the eight lithium batteries in the two groups of type A lithium battery packs are closed and connected, and the first electrically controlled single-cut switches connected in parallel with the eight first electrically controlled double-cut switches are opened, and the first electrically controlled double-cut switches corresponding to the extended copper bars on the four lithium batteries in the type B lithium battery packs are opened, and the first electrically controlled single-cut switches connected in parallel with the four first electrically controlled double-cut switches are opened. The single-cut switch will be turned off and on. During the power supply process, the lithium batteries in the eight A-type lithium battery packs will continue to consume power. When the average power of the eight lithium batteries in the A-type lithium battery pack is lower than 80% of the average power of the four lithium batteries in the B-type lithium battery pack, the four lithium batteries with the lowest power among the eight lithium batteries in the A-type lithium battery pack will be obtained through the BMS communication module, and the power supply of the four lithium batteries with the lowest power in the A-type lithium battery pack will be disconnected, and the replacement mode will be started to replace the four lithium batteries 1 in the B-type lithium battery pack with power;

[0018] S2: After the first replacement mode is performed in step S1, the four lithium batteries in the working A-type lithium battery pack continue to work until the average power of the four lithium batteries is less than 60%. Then, the second replacement mode will be performed, and the four lithium batteries in the A-type lithium battery pack replaced in the first replacement will continue to supply power. In the subsequent replacement mode, there will be no distinction between A-type lithium battery packs and B-type lithium battery packs. The four lithium batteries with the lowest power among the eight working lithium batteries will be replaced;

[0019] S3: If multiple replacements are performed after step S2, when the eight lithium batteries are low in power and the supply voltage is low, the starting lithium battery or batteries are connected in series to supply power so that the supply voltage meets the requirement. At this time, the remaining two or three lithium batteries will start active equalization charging;

[0020] S4: In the step S3, active balanced charging is performed, and one of the two balanced lithium batteries is started to supply power or the two batteries are connected in series to supply power. When the balanced lithium battery supplies power, the DC / AC converter converts the direct current into alternating current and circulates it in the loop conductor. When the remaining two or three lithium batteries are in the A-type lithium battery pack or the B-type lithium battery pack, the electronically controlled balanced starting switch connected in parallel to the positive winding position of the corresponding transformer of the A-type lithium battery pack or the B-type lithium battery pack is turned on. At the same time, the electronically controlled series starting switch on the positive winding of the transformer is turned off, and the electronically controlled balanced starting switch that is not connected in parallel to the corresponding positive winding position of the transformer is in the off state, and the corresponding electronically controlled series starting switch is turned on. If the positive winding of the transformer is energized, it will provide interactive magnetic flux lines to the corresponding secondary winding of the transformer, and the secondary winding of the transformer will generate alternating current. The alternating current generated by the secondary winding of the transformer is converted into direct current through the AC / DC converter. When a certain lithium battery needs balanced charging, the second electronically controlled double-cut switch connected to it is closed and connected to perform balanced charging on its lithium battery.

[0021] S5: In step S4, the average power level of the lithium batteries being balanced charged is M1. Among the lithium batteries currently supplying power, the same number of lithium batteries as the number of lithium batteries being balanced charged are selected, and the average power level of the lithium batteries with the lowest power level, M2, is calculated. If the power level of M1 is 20% higher than M2, a replacement mode is activated, and the balanced charging of the lithium batteries being balanced charged is cut off to replace the lithium batteries with the lowest power levels. The replaced lithium batteries with the lowest power levels will then start the balanced charging mode. Step S5 is repeated in this way to achieve balanced power supply for the entire lithium battery system.

[0022] In other embodiments of the present invention, if there are no lithium batteries with a charge of more than 95% when two groups of type A lithium battery packs and one group of type B lithium battery packs are started to supply power, the two groups of type A lithium battery packs are not prioritized for power supply. Instead, power supply is performed according to the mode after the second replacement mode in step S2, and the subsequent power supply balancing mode is the same as steps S3 to S5.

[0023] In other embodiments of the present invention, if the charge level of all lithium batteries is less than 40%, the lithium battery being balanced requires rapid charging to complete the replacement mode and replace the frequency. In this case, two balanced lithium batteries are activated in series to provide higher voltage balanced charging. When the balanced lithium batteries are activated in series, the transformer secondary winding activates the entire transformer secondary winding to receive the alternating magnetic flux lines emitted by the transformer positive winding, thereby obtaining higher voltage and current for balanced charging and increasing the charging speed.

[0024] In other embodiments of the present invention, if a group of lithium batteries is supplying power and the discharge rate of one or several batteries is significantly higher than that of other lithium batteries supplying power, the power supply of the batteries with significantly higher power supply speeds will be cancelled and marked, and no equalizing charging will be performed. At the same time, the spare lithium batteries will be replaced according to the number of batteries supplying power. If the number of batteries with significantly higher power supply speeds is greater than or equal to four, the power supply of these batteries with significantly higher power supply speeds will not be cancelled, but will still be marked.

[0025] In other embodiments of the present invention, if the power levels of the lithium batteries in both the two A-type lithium battery packs and one B-type lithium battery pack are less than 20%, equalization charging of the spare batteries cannot be initiated. In this case, synchronous equalization charging of the power supply lithium battery is initiated.

[0026] In the present invention, the redundant and idle lithium batteries are preferentially used to replace the lithium batteries with low power in the working lithium batteries to realize balanced power supply of the lithium batteries, reduce the large power loss of the traditional balanced power supply, which is not conducive to power supply, and use two balanced lithium batteries to balance the charging of all low-power lithium batteries (less than 50% power). The ones that are supplying power are still supplying power, and the ones that are not supplying power are charged, so as to prevent the low-power lithium batteries at the back from having different power levels or even being unable to supply power, resulting in a low overall power supply voltage and failure to meet power supply requirements.

[0027] Balanced power supply can ensure that the power difference of all the low-power lithium batteries at the back is reduced and that they can all be supplied with power to maximize the use of the remaining low power.

[0028] It can accurately judge the battery power and power supply requirements, ensure fast balanced charging of low-power lithium batteries, and replace new low-power lithium batteries for power supply. The balanced charging replacement speed is fast, ensuring balanced charging efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0030] Figure 1 This is a structural diagram of a lithium battery BMS active balancing system proposed by the present invention.

[0031] Figure 2 This is a structural diagram of a lithium battery BMS active balancing system proposed by the present invention (the integrated box of the power supply circuit and the balancing energy circuit is removed).

[0032] Figure 3 This is a schematic structural diagram of the lithium battery module proposed in the present invention.

[0033] Figure 4 This is a schematic structural diagram of a single lithium battery proposed in the present invention.

[0034] Figure 5 This is a schematic diagram of the power supply circuit principle proposed by the present invention.

[0035] Figure 6 This is a schematic diagram of the principle of the equalization and charging circuit proposed by the present invention.

[0036] In the figure, 1. lithium battery; 2. balancing lithium battery; 21. balancing power supply tab; 211. first charging single-cut switch; 212. second charging single-cut switch; 213. third charging single-cut switch; 3. control management box; 4. integrated box of power supply circuit and balancing energy circuit; 5. tab; 51. upper extended copper busbar; 511. first electrically controlled double-cut switch; 512. first electrically controlled single-cut switch; 52. lower extended copper busbar; 521. second electrically controlled double-cut switch; 6. first electrically controlled double-cut switch; 61. positive winding of transformer; 611. electrically controlled series-connected starting switch; 612. electrically controlled balancing starting switch; 7. AC / DC converter; 8. secondary winding of transformer; 81. first voltage conversion electrically controlled single-cut switch; 82. second voltage conversion electrically controlled single-cut switch; 9. DC / AC converter; 10. insulating pad. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0038] Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, but are not to be construed as limiting the present invention.

[0039] Reference Figure 1-6 , a lithium battery BMS active balancing system, including a lithium battery power supply module, a lithium battery balancing module, a control management box 3 and an integrated box 4 of a power supply circuit and a balancing energy circuit;

[0040] The lithium battery power supply module includes two groups of type A lithium battery groups and one group of type B lithium battery groups. The number of lithium batteries 1 in each of the type A lithium battery group and the type B lithium battery group is four, and the lithium battery 1 is of the same model. The three groups of lithium battery groups are arranged in a row, and the tabs 5 on the top of the lithium battery 1 are arranged on the same straight line near the right edge. The two positive and negative tabs on the top of each lithium battery 1 have the same structure. The tabs include tab posts, an upper extended copper busbar 51, and a lower extended copper busbar 52.

[0041] The structure of the A-type lithium battery pack is the same as that of the B-type lithium battery pack. The B-type lithium battery pack can also be divided into two for replacement and balancing according to the performance of the lithium battery 1.

[0042] The lithium battery balancing module includes two balancing lithium batteries 2, and two balancing power supply tabs 21 are provided on the right side of the top of the two balancing lithium batteries 2;

[0043] The control management box 3 is provided with a microcontroller (MCU) and a BMS communication module, and the microcontroller is electrically connected to the BMS communication module; BMS communication is the communication of the battery management system (Battery Management System), which refers to the process of data transmission and interaction between the BMS and other systems or devices.

[0044] The integrated box 4 of the power supply circuit and the balanced energy circuit is provided with an upper and lower layered board. The upper layer of the integrated box 4 of the power supply circuit and the balanced energy circuit has a power supply circuit, and the lower layer has a balanced and charging circuit; the two layers do not interfere with each other.

[0045] The power supply circuit includes two power supply wires, multiple first electrically controlled double-cut switches 511 and multiple first electrically controlled single-cut switches 512. The two power supply wires are arranged in parallel and connected by a wire at the same end, and the other end is the output end. The first power supply wire is parallel to the tabs 5 on the top of all lithium batteries 1 in a straight line. The upper extended copper bus 51 on the positive and negative tabs of each lithium battery 1 is respectively connected to the two interfaces of the input end of a first electrically controlled double-cut switch 511. The two output wires at the output end of the first electrically controlled double-cut switch 511 are connected to two points of the first power supply wire, and the power supply wire between the two points is connected to the first electrically controlled single-cut switch 512. The first electrically controlled double-cut switch 511 and the first electrically controlled single-cut switch 512 are used to switch whether the lithium battery 1 is connected in series for power supply.

[0046] The balancing and charging circuit includes an input balancing circuit and three identical output balancing circuits. The input balancing circuit includes a DC / AC converter 9, a loop conductor 6, and three sets of transformer positive windings 61. The two interfaces at the output end of the DC / AC converter 9 are electrically connected by the two ends of the loop conductor 6. Three electrically controlled balancing start switches 612 are evenly spaced on the loop conductor 6. On each loop conductor 6 at the position of the electrically controlled balancing start switch 612, a transformer positive winding 61 is connected in parallel on both sides of the electrically controlled balancing start switch 612. An electrically controlled series start switch 611 is provided on the input end of the transformer positive winding 61. The loop conductor 6 is connected to two external charging wires at the output end of the DC / AC converter 9. The output balancing circuit includes an AC / DC converter 7, a transformer secondary winding 8, and four second electrically controlled double-cut switches 5. 21. The two input ends of the AC / DC converter 7 are respectively connected to a transformer secondary winding 8 and an extension wire. The transformer secondary winding 8 is parallel to a corresponding transformer positive winding 61. The transformer secondary winding 8 is provided with a switching wire electrically connected to the extension wire at the middle position and the tail position, respectively. Both switching wires are provided with a first voltage conversion electrically controlled single-cut switch 81 and a second voltage conversion electrically controlled single-cut switch 82. The output end of the AC / DC converter 7 will be provided with two balancing wires. The input ends of four second electrically controlled double-cut switches 521 are connected in series in parallel to the two balancing wires. Each output balancing circuit corresponds to a lithium battery pack, and the output ends of the four second electrically controlled double-cut switches 521 on the output balancing circuit are respectively electrically connected to the lower extended copper bus 52 on four lithium batteries 1 in a lithium battery pack.

[0047] The DC / AC converter 9 is a DC to AC converter, and the AC / DC converter 7 is an AC to DC converter.

[0048] Each of the two balancing power supply tabs 21 on the top of the two balancing lithium batteries 2 has a charging wire. The two charging wires on the two balancing power supply tabs on the top of one of the balancing lithium batteries 2 are provided with a first charging single disconnect switch 211, and the two charging wires on the two balancing power supply tabs 21 on the top of the other balancing lithium battery 2 are provided with a second charging single disconnect switch 212. A third charging single disconnect switch 213 is provided on the wires electrically connected between the two closest positive balancing power supply tabs 21 and the negative balancing power supply tab 21 on the top of the two balancing lithium batteries 2. The charging wires on the two balancing power supply tabs 21 on the top of the two balancing lithium batteries 2 are both connected to the input terminals of the DC / AC converter 9.

[0049] When the first balancing lithium battery 2 is independently balancing charged, the first charging disconnect switch 211 is closed, while the second and third charging disconnect switches 212, 213 are open. When the second balancing lithium battery 2 is independently balancing charged, the second charging disconnect switch 212 is closed, while the first and third charging disconnect switches 211, 213 are open. When connected in series, the third charging disconnect switch 213 between the two balancing power supply lugs 21 is closed, and the corresponding first and second charging disconnect switches 211, 212 on the two balancing power supply lugs 21 are open. The other two first and second charging disconnect switches 211, 212 are closed.

[0050] The BMS communication module is used to obtain voltage information and power information of each lithium battery in the three groups of lithium batteries, and the microcontroller is used to control all electronically controlled double-cut switches and electronically controlled single-cut switches on the power supply circuit, the balancing and charging circuit, and the balancing lithium battery output circuit.

[0051] The two Type A lithium battery packs are the priority power supply packs, while the Type B lithium battery packs are the balancing replacement packs. To meet the required power supply voltage, each lithium battery pack must be at least 50% charged, and at least eight lithium batteries are required. At least two lithium battery packs are required for power supply. This ensures that fewer lithium batteries are not used for power supply, reducing energy consumption during vehicle operation.

[0052] The two balancing lithium batteries 2 are of the same model, and their capacity is 2-3 times that of a single lithium battery 1. This ensures balanced charging and backup power. The two balancing lithium batteries 2 can be charged using independent charging systems, or the DC / AC converter 9 has reverse conversion capabilities, allowing reverse charging using two external charging leads.

[0053] An insulating pad 10 is inserted between the lithium battery power supply module, the lithium battery balancing module, and the control and management box 3. The lithium battery balancing module is flush with the top of the control and management box 3 and is also inserted between the lithium battery balancing module and the integrated box 4 of the balancing energy circuit. This ensures the safety of the stock system.

[0054] A lithium battery BMS active balancing method uses the above-mentioned lithium battery BMS active balancing system to achieve balancing. The specific balancing steps are as follows:

[0055] S1: When two groups of type A lithium battery packs and one group of type B lithium battery packs are fully charged, the two groups of type A lithium battery packs are started first to supply power, the first electrically controlled double-cut switches 511 corresponding to the extended copper bars 51 on the eight lithium batteries in the two groups of type A lithium battery packs are closed and connected, and the first electrically controlled single-cut switches 512 connected in parallel with the eight first electrically controlled double-cut switches 511 are opened, and the first electrically controlled double-cut switches 511 corresponding to the extended copper bars on the four lithium batteries 1 in the type B lithium battery packs are opened and connected in parallel with the four first electrically controlled double-cut switches 511. The first electrically controlled single-cut switch 512 is closed and connected. During the power supply process, the lithium batteries 1 in the eight A-type lithium battery packs will continue to consume power. When the average power of the eight lithium batteries 1 in the A-type lithium battery pack is lower than 80% of the average power of the four lithium batteries in the B-type lithium battery pack, the BMS communication module obtains the four lithium batteries 1 with the lowest power among the eight lithium batteries in the A-type lithium battery pack, disconnects the four lithium batteries 1 with the lowest power in the A-type lithium battery pack, and starts the replacement mode to replace the four lithium batteries 1 in the B-type lithium battery pack with power.

[0056] S2: After the first replacement mode is performed in step S1, the four lithium batteries 1 in the working A-type lithium battery pack continue to work until the average power of the four lithium batteries is less than 60%. Then, the second replacement mode will be performed, and the four lithium batteries 1 in the A-type lithium battery pack replaced in the first replacement will continue to supply power. In the subsequent replacement mode, there is no longer a distinction between A-type lithium battery packs and B-type lithium battery packs. The four lithium batteries with the lowest power among the eight working lithium batteries will be replaced.

[0057] S3: If multiple replacements are performed after step S2, when eight lithium batteries are low in power and the supply voltage is low, nine or ten lithium batteries 1 will be started in series to supply power so that the supply voltage meets the requirement. At this time, the remaining two or three lithium batteries will start active equalization charging;

[0058] S4: In the step S3, active balanced charging is performed, and one of the two balanced lithium batteries 2 is started to supply power or the two are connected in series to supply power. When the balanced lithium battery 2 supplies power, the DC power is converted into AC power by the DC / AC converter 9 and circulated in the loop conductor 6. When the remaining two or three lithium batteries 1 are in the A-type lithium battery group or the B-type lithium battery group, the electronically controlled balanced starting switch 612 connected in parallel to the positive winding 61 of the transformer corresponding to the A-type lithium battery group or the B-type lithium battery group is turned on. At the same time, the electronically controlled starting switch 61 connected in series on the positive winding 61 of the transformer is turned on. 1 is closed, and there is no corresponding electrically controlled balancing start switch 612 connected in parallel with the transformer positive winding 61. The corresponding electrically controlled series start switch 611 is turned on. If the transformer positive winding 61 is energized, it will provide interactive magnetic flux lines to the corresponding transformer secondary winding 8, and the transformer secondary winding 8 will generate AC power. The AC power generated by the transformer secondary winding 8 is converted into DC power through the AC / DC converter 7. When a lithium battery 1 needs balanced charging, the second electrically controlled double-cut switch 521 connected to it is closed and connected to perform balanced charging on the lithium battery 1.

[0059] S5: In step S4, the average power of the lithium batteries being balanced charged is M1. Among the lithium batteries currently supplying power, the lithium batteries 1 with the same number of batteries being balanced charged are selected, and the average power of the lithium batteries with the lowest power, M2, is calculated. If the power of M1 is 20% higher than M2, a replacement mode is activated, and the balanced charging of the lithium batteries 1 being balanced charged is interrupted to replace the lithium batteries 1 with the lowest power. The replaced lithium batteries 1 with the lowest power will then start the balanced charging mode. Step S5 is repeated in this way to achieve balanced power supply for the entire lithium battery system.

[0060] If you want to reduce the difference in power between lithium batteries 1, you can adjust the replacement mode to 10% difference, which will accurately replace 8% or 5%. The replacement mode is inconvenient. The balancing method mainly relies on alternating power between the 12 lithium batteries. Only when the power level is below 50, the supply voltage is insufficient, or even when the battery power is still low after replacement, the balancing charging is activated to ensure that each lithium battery 1 is working normally and will not be too low in power to supply power.

[0061] If there is no lithium battery 1 with a charge of more than 95% when the two groups of type A lithium battery packs and the one group of type B lithium battery packs are started to supply power, the two groups of type A lithium battery packs are not prioritized for power supply. Instead, power supply is performed according to the mode after the second replacement mode in step S2. The subsequent power supply balancing mode is the same as steps S3 to S5.

[0062] When the battery is not fully charged at the beginning, the system will prioritize supplying power from the highest-charged lithium battery according to the detected lithium battery power status, and then enter the replacement mode. The overall system will circulate the power to a certain extent in the battery, so that the power difference between the lithium batteries is always kept small.

[0063] If the charge level of all lithium batteries 1 is less than 40%, the lithium batteries being balanced need to be quickly charged to complete the replacement mode and replace the frequency. At this time, the two balanced lithium batteries 2 are activated in series to provide higher voltage balanced charging. When the balanced lithium batteries 2 are activated in series, the transformer secondary winding 8 will activate the entire transformer secondary winding 8 to receive the alternating magnetic flux lines emitted by the transformer positive winding 61, obtaining higher voltage and current for balanced charging, thereby increasing the charging speed.

[0064] Later, the power is low, and only fast equalization charging can ensure that there is no situation where the lithium battery is too low to supply power, unless the power of the two equalization lithium batteries 2 is also low.

[0065] If a group of lithium batteries 1 is supplying power and the discharge rate of one or several batteries is significantly higher than that of other lithium batteries 1, the batteries with significantly higher power supply rate will be removed from the supply and marked, and no equalizing charging will be performed. At the same time, the spare lithium batteries will be replaced according to the number of batteries. If the number of batteries with significantly higher power supply rate is greater than or equal to four, the batteries with significantly higher power supply rate will not be removed from the supply, but will still be marked.

[0066] When there are a large number of abnormal power supply lithium batteries, only temporary power supply is guaranteed, and it cannot be stopped. Otherwise, it cannot be used for power supply and can be repaired or replaced later.

[0067] If the power level of the lithium batteries in two groups of type A lithium battery packs and one group of type B lithium battery packs is less than 20%, the equalization charging of the spare batteries cannot be started. At this time, the lithium batteries that are powered are started for synchronous equalization charging.

[0068] When the power of lithium battery 1 is very low, if the equalization charging and replacement mode are switched, there will not be enough time for equalization charging, and some lithium batteries may be out of power. In this case, equalization lithium battery 2 can be connected in parallel with the lithium battery to supply power. That is, during equalization charging, lithium battery 1 is also started to supply power to ensure normal driving power.

[0069] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A lithium battery BMS active balancing system, characterized by: It comprises a lithium battery power supply module, a lithium battery balancing module, a control management box (3) and an integrated box (4) of a power supply circuit and a balancing energy circuit; The lithium battery power supply module comprises two groups of type A lithium battery groups and one group of type B lithium battery groups, the number of lithium batteries (1) in each of the type A lithium battery group and the type B lithium battery group is four and the model of the lithium batteries (1) is the same, the three groups of lithium battery groups are arranged in a row, and the pole ears (5) on the top of the lithium battery (1) are arranged on the same straight line close to the right side, the two positive and negative pole ears on the top of each lithium battery (1) have the same structure, and the pole ears include pole ear columns, upper extended copper bars (51) and lower extended copper bars (52); The lithium battery balancing module comprises two balancing lithium batteries (2), and two balancing power supply tabs (21) are provided on the right sides of the tops of the two balancing lithium batteries (2); The control management box (3) is provided with a microcontroller and a BMS communication module, and the microcontroller is electrically connected to the BMS communication module; The integrated box (4) of the power supply circuit and the balanced energy circuit is provided with an upper and lower layered board, wherein the upper layer of the integrated box (4) of the power supply circuit and the balanced energy circuit contains a power supply circuit, and the lower layer contains a balanced and charging circuit; The power supply circuit comprises two power supply wires, a plurality of first electrically controlled double-cut switches (511) and a plurality of first electrically controlled single-cut switches (512), the two power supply wires being arranged in parallel and connected by a wire at the same end, and the other end being an output end, the first power supply wire being parallel to the pole ears (5) at the top of all lithium batteries (1) in a straight line, the upper outer extension copper bar (51) on the positive and negative pole ears of each lithium battery (1) being respectively connected to two interfaces at the input end of a first electrically controlled double-cut switch (511), the two output wires at the output end of the first electrically controlled double-cut switch (511) being connected to two points of the first power supply wire, and the power supply wire between the two points is connected to the first electrically controlled single-cut switch (512); The balancing and charging circuit comprises an input balancing circuit and three identical output balancing circuits. The input balancing circuit comprises a DC / AC converter (9), a loop conductor (6) and three sets of transformer positive windings (61). Two interfaces at the output end of the DC / AC converter (9) are electrically connected by two ends of the loop conductor (6). Three electrically controlled balancing start switches (612) are arranged at equal intervals on the loop conductor (6). On each loop conductor (6) at the position of the electrically controlled balancing start switch (612), a transformer positive winding (61) is connected in parallel on both sides of the electrically controlled balancing start switch (612). An electrically controlled series start switch (611) is arranged at the input end of the transformer positive winding (61). Two external charging conductors are connected to the loop conductor (6) at the output end of the DC / AC converter (9). The output balancing circuit comprises an AC / DC converter (7), a transformer secondary winding (8) and four second electrically controlled dual windings. A switch (521), two input ends of the AC / DC converter (7) are respectively connected to a transformer secondary winding (8) and an extension wire, the transformer secondary winding (8) is parallel to a corresponding transformer positive winding (61), a switching wire electrically connected to the extension wire is respectively provided at the middle position and the tail end position of the transformer secondary winding (8), and the two switching wires are both provided with a first voltage conversion electrically controlled single switch (81) and a second voltage conversion electrically controlled single switch (82), the output end of the AC / DC converter (7) is provided with two balancing wires, the input ends of four second electrically controlled double switches (521) are connected in series in parallel to the two balancing wires, each of the output balancing circuits corresponds to a group of lithium battery packs, and the output ends of the four second electrically controlled double switches (521) on the output balancing circuit are respectively electrically connected to the lower extended copper busbars (52) on four lithium batteries (1) in a group of lithium battery packs; The two balancing power supply lugs (21) on the top of the two balancing lithium batteries (2) are each provided with a charging wire, the two charging wires on the two balancing power supply lugs on the top of one of the balancing lithium batteries (2) are provided with a first charging single-cut switch (211), the two charging wires on the two balancing power supply lugs (21) on the top of the other balancing lithium battery (2) are provided with a second charging single-cut switch (212), the wires electrically connected between the two closest positive balancing power supply lugs (21) and the negative balancing power supply lug (21) on the top of the two balancing lithium batteries (2) are provided with a third charging single-cut switch (213), and the charging wires on the two balancing power supply lugs (21) on the top of the two balancing lithium batteries (2) are both connected to the input end of the DC / AC converter (9) accordingly; The BMS communication module is used to obtain the voltage information and power information of each lithium battery in the three groups of lithium batteries, and the microcontroller is used to control all the electrically controlled double-cut switches and electrically controlled single-cut switches on the power supply circuit, the balancing and charging circuit, and the balancing lithium battery output circuit.

2. A lithium battery BMS active equalization system according to claim 1, characterized in that: The two groups of A-type lithium battery packs are priority power supply lithium battery packs, and the B-type lithium battery packs are balanced replacement lithium battery packs. When the power supply voltage requirement is met, it must be ensured that the power of each lithium battery (1) is above 50% and at least eight lithium batteries are required.

3. A lithium battery BMS active equalization system according to claim 1, characterized in that: The two balancing lithium batteries (2) are of the same model, and the battery capacity of the balancing lithium batteries (2) is 2-3 times the capacity of one lithium battery (1).

4. A lithium battery BMS active equalization system according to claim 1, characterized in that: An insulating pad (10) is inserted between the lithium battery power supply module, the lithium battery balancing module and the control management box (3); the lithium battery balancing module is flush with the top of the control management box (3) and an insulating pad (10) is also inserted between the lithium battery balancing module and the integrated box (4) of the balancing energy circuit.

5. A lithium battery BMS active balancing method, characterized in that: The lithium battery BMS active balancing system according to any one of claims 1 to 4 is used to achieve balancing, and the specific balancing steps are as follows: S1: When two groups of A-type lithium battery groups and one group of B-type lithium battery groups are both fully charged, the two groups of A-type lithium battery groups are started first to supply power, the first electrically controlled double-cut switches (511) corresponding to the extended copper bars (51) on the eight lithium batteries in the two groups of A-type lithium battery groups are closed and connected, and the first electrically controlled single-cut switches (512) connected in parallel with the eight first electrically controlled double-cut switches (511) are opened, and the first electrically controlled double-cut switches (511) corresponding to the extended copper bars on the four lithium batteries (1) in the B-type lithium battery group are opened and connected in parallel with the four first electrically controlled double-cut switches (511) The first electrically controlled single-cut switch (512) connected in parallel is turned off and on. During the power supply process, the eight lithium batteries (1) in the A-type lithium battery group will continue to consume power. When the average power of the eight lithium batteries (1) in the A-type lithium battery group is lower than 80% of the average power of the four lithium batteries in the B-type lithium battery group, the four lithium batteries (1) with the lowest power among the eight lithium batteries in the A-type lithium battery group are obtained through the BMS communication module, and the power supply of the four lithium batteries (1) with the lowest power in the A-type lithium battery group is disconnected, and the replacement mode is started to replace the four lithium batteries (1) in the B-type lithium battery group for power supply; S2: After a replacement mode is performed in step S1, the four lithium batteries (1) in the working A-type lithium battery group continue to work until the average power of the four lithium batteries is less than 60%, and then a second replacement mode will be performed, and the four lithium batteries (1) in the A-type lithium battery group replaced for the first time will continue to supply power. In the subsequent replacement mode, the A-type lithium battery group and the B-type lithium battery group will no longer be divided, and the four lithium batteries with the lowest power among the eight working lithium batteries will be replaced; S3: If multiple replacements are performed after step S2, when the power of eight lithium batteries is low and the power supply voltage is low, nine or ten lithium batteries (1) will be started to supply power in series so that the power supply voltage reaches the requirement. At this time, the remaining two or three lithium batteries will start active equalization charging; S4: In the step S3, active balanced charging is performed, one of the two balanced lithium batteries (2) is started to supply power or the two are connected in series to supply power. When the balanced lithium battery (2) supplies power, the DC / AC converter (9) converts the direct current into alternating current and circulates it in the circulation conductor (6). When the remaining two or three lithium batteries (1) are in the A-type lithium battery group or the B-type lithium battery group, the electrically controlled balanced starting switch (612) connected in parallel to the positive winding (61) of the A-type lithium battery group or the B-type lithium battery group corresponding to the transformer is turned on. At the same time, the electrically controlled series starting switch (611) on the positive winding (61) of the transformer is turned off. The transformer positive winding (61) is closed, and the electrically controlled balancing start switch (612) connected in parallel without the corresponding transformer positive winding (61) is in the closed state, and the corresponding electrically controlled serial start switch (611) is opened. If the transformer positive winding (61) is energized, it will provide the corresponding transformer secondary winding (8) with alternating magnetic flux lines, and the transformer secondary winding (8) will generate alternating current. The alternating current generated by the transformer secondary winding (8) is converted into direct current through the AC / DC converter (7). When a lithium battery (1) needs to be charged in a balanced manner, the second electrically controlled double-cut switch (521) connected thereto is closed and connected to charge the lithium battery (1) in a balanced manner. S5: In step S4, the average power of the lithium batteries being balanced charged is M1, and the lithium batteries (1) with the same number of the lithium batteries being balanced charged are selected from the lithium batteries being powered, and the average power of the lithium batteries with the lowest power M2 is calculated. If the power of M1 is 20% higher than that of M2, a replacement mode will be performed, and the balanced charging of the lithium batteries (1) being balanced charged will be cut off to replace the lithium batteries (1) with the lowest power. The replaced lithium batteries (1) with the lowest power will start the balanced charging mode charging, and step S5 will be repeated in this way to achieve balanced power supply of the entire lithium battery.

6. A lithium battery BMS active balancing method according to claim 5, characterized in that: If there is no lithium battery (1) with a power level of more than 95% when the two groups of A-type lithium battery groups and one group of B-type lithium battery groups are started to supply power, the two groups of A-type lithium battery groups are not started first to supply power, but the power supply is carried out in the mode after the second replacement mode in step S2, and the subsequent power supply balance mode is the same as steps S3 to S5.

7. A lithium battery BMS active balancing method according to claim 5, characterized in that: If the power of all lithium batteries (1) is less than 40%, the lithium batteries being balanced charged need to be quickly charged to complete the replacement mode replacement frequency. At this time, the two balanced lithium batteries (2) are started in series to provide a higher voltage balanced charging. When the balanced lithium batteries (2) are started in series, the transformer secondary winding (8) will start the entire transformer secondary winding (8) to receive the alternating magnetic flux lines emitted by the transformer positive winding (61), thereby obtaining a higher voltage and current for balanced charging to increase the charging speed.

8. A lithium battery BMS active balancing method according to claim 5, characterized in that: If a group of lithium batteries (1) are supplying power and the discharge speed of one or several of them is obviously higher than that of other lithium batteries (1) supplying power, the batteries with obviously higher power supply speed will be removed from power supply and marked, and no more equalization charging will be performed. At the same time, the spare lithium batteries will be replaced according to the number of batteries for power supply. If the number of batteries with obviously higher power supply speed is greater than or equal to four, the lithium batteries with obviously higher power supply speed will not be removed from power supply, but will still be marked.

9. A lithium battery BMS active balancing method according to claim 5, characterized in that: If the power of the lithium batteries in two groups of A-type lithium battery groups and one group of B-type lithium battery groups is less than 20%, the equalization charging of the spare batteries cannot be started. At this time, the lithium batteries that start power supply are synchronously equalized charged.

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