Active equalization device and method for battery packs, and serial battery pack system

Abstract

The present invention relates to battery equalization technology, and disclosed are an active equalization device and method for serial battery packs, and a serial battery pack system. The device comprises a master control unit, a plurality of first communication units, and a plurality of cell equalization units, wherein each first communication unit comprises a cell information collection port and an equalization circuit connection port, and the first communication units transmit, to the cell equalization units by means of the equalization circuit connection ports, a power drawing instruction sent by the master control unit; each cell equalization unit comprises a first power drawing port, and power is drawn from a total voltage port for the serial battery packs by means of the first power drawing ports to charge cells; and the master control unit is communicationally connected to the first communication units, and comprises a power supply module, wherein the power supply module draws power from the total voltage port for the serial battery packs and transmits the power to the cell equalization units by means of the first power drawing ports. The present solution uses an energy conversion mode to implement active equalization of battery packs.

Description

Battery pack active balancing device, method, and battery pack series connection system

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on June 27, 2023, with application number 202310754285.7 and entitled “Battery Pack Active Balancing Device, Method, and Battery Pack Series System,” the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present invention relates to battery balancing technology, and in particular to a battery pack active balancing device, method, and battery pack series connection system. Background Art

[0003] When lithium batteries are used in series, due to the differences in internal resistance and capacity of each battery, as well as the differences in self-consumption, after a period of use, the capacity of each cell in the lithium battery will be inconsistent, and the differences will become larger and larger, eventually forming a short-board effect. The capacity of the entire lithium battery is determined by the cell with the smallest capacity, resulting in a short overall life of the lithium battery.

[0004] A common balancing technology is passive balancing, which is a method of releasing energy from higher-voltage cells through resistors. Although the technology is simple, releasing energy through resistors results in energy waste. This method also generates a lot of heat and requires heat dissipation, which requires additional heat dissipation technology. At the same time, this method has a small balancing current and a long balancing time.

[0005] Currently, common balancing technologies determine the capacity of the entire battery pack by the smallest cell. For parallel systems, each battery pack only needs to achieve active internal balancing. However, for series systems, not only must all cells within the pack be balanced consistently, but also between packs. There is currently no simple solution for achieving consistent balance between battery packs in a series system.

[0006] Summary of the Invention

[0007] The present invention addresses the shortcomings of the prior art and provides a battery pack active balancing device.

[0008] In a first aspect, the present invention discloses an active balancing device for a series battery pack, comprising a main control unit, a plurality of first communication units and a plurality of cell balancing units, wherein:

[0009] The first communication unit includes a cell information acquisition port, a balancing circuit connection port, and a main control unit connection port. The first communication unit collects cell information through the cell information acquisition port and transmits it to the main control unit through the main control unit connection port. The first communication unit transmits a power-taking instruction sent by the main control unit to the cell balancing unit through the balancing circuit connection port.

[0010] The cell balancing unit includes a first power-taking port, through which power is taken from the total voltage port of the series-connected battery pack to charge the cell;

[0011] The main control unit is communicatively connected to the first communication unit, and the main control unit includes a power supply module. The power supply module draws power from the total voltage of the series-connected battery pack and transmits the power to the cell balancing unit through the first power supply port.

[0012] In one implementation, the main control unit further includes a control module and a second communication unit, wherein:

[0013] The power supply module is electrically connected to the control module;

[0014] The control module is connected to the second communication unit, the second communication unit is connected to the first communication unit, and the control module communicates with the cell balancing unit and the cell through the first communication unit and the second communication unit.

[0015] In one implementation, the first communication unit includes a battery information acquisition module and a power-taking instruction interaction module, wherein:

[0016] The battery information collection module collects information about the single battery pack and information about each cell in the battery pack;

[0017] The power-taking instruction interaction module is connected to the cell balancing unit and exchanges power-taking instructions with the cell balancing unit. The power-taking instructions include battery pack information and information about cells in the battery pack that need to be charged.

[0018] In one implementation, the main control unit further includes a main control isolation module, and the main control isolation module is connected to the power supply module and the first power port of the cell balancing unit.

[0019] In one implementation, the cell balancing unit includes a slave isolation module and a cell balancing circuit, the slave isolation module is connected to the cell balancing circuit, the slave isolation module is connected to the first power supply port, and power is taken from the total voltage port of the series battery pack through the first power supply port.

[0020] In one implementation, the power supply module further includes a step-down module, the step-down module includes a second power supply port, and the second power supply port draws power from a total voltage port of the series-connected battery pack.

[0021] In a second aspect, the present invention discloses a method for active balancing of a series-connected battery pack, which is implemented using the above-mentioned active balancing device for a series-connected battery pack, comprising the following steps:

[0022] Step 10: The main control unit obtains battery information through the first communication unit;

[0023] Step 20: The main control unit determines whether the cell balancing condition is met based on the battery information. If so, the main control unit feeds back a power-up instruction to the cell balancing unit; if not, the main control unit waits to receive new battery information.

[0024] In step 30 , after receiving the power-taking instruction, the cell balancing unit takes power from the total voltage port of the series-connected battery pack through the first power-taking port to charge the corresponding cells that meet the cell balancing conditions.

[0025] In one implementation, step 20 further includes:

[0026] Step 21: When the voltage difference between the lowest battery pack voltage and the highest battery pack voltage in the current battery information obtained by the main control unit is greater than a threshold, the main control unit feeds back a power-off instruction to the cell balancing unit; the power-off instruction includes the battery pack information and the cell information in the corresponding battery pack;

[0027] Step 22: The cell balancing unit selects the cell with the lowest voltage in the battery pack with the lowest voltage according to the power extraction instruction, draws power through the first power extraction port, and charges the selected cell until the voltages of all cells in the selected battery pack are balanced.

[0028] In step 23, after completing the balancing of the internal cells of a group of battery packs, the main control unit waits to receive new battery information, and then repeats steps 21 to 22 until the voltage difference between the lowest battery pack voltage and the highest battery pack voltage is less than or equal to the threshold.

[0029] In one implementation, the battery information includes voltage information and battery pack numbers of each battery pack connected in series, and voltage information and battery cell numbers of each battery pack.

[0030] In a third aspect, the present invention further discloses a battery pack series system, comprising a plurality of battery packs connected in series and the above-mentioned active balancing device for the series-connected battery packs;

[0031] The battery pack series connection system further includes a total voltage port electrically connected to the plurality of battery packs connected in series and configured to output a total voltage of the battery packs connected in series;

[0032] Each of the battery packs includes a plurality of battery cells connected in series, each battery cell is electrically connected to the battery cell balancing unit, and the battery cell balancing unit is electrically connected to the total voltage port; the battery cells are communicatively connected to the main control unit via the first communication unit.

[0033] Beneficial effects of the present invention:

[0034] The solution proposed in this invention is to achieve equalization of the battery pack through active balancing. By setting up a voltage bus, equalization is achieved through energy transfer rather than consumption. The energy of higher capacity cells is transferred to lower capacity cells, achieving full utilization of the battery pack cells and solving the weak link effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0036] Figure 1 is a schematic diagram of an active balancing device for a series battery pack. DETAILED DESCRIPTION

[0037] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0038] The terms "first," "second," and the like in the specification, claims, and accompanying drawings of this application are used to distinguish between different objects, not to describe a particular order. Furthermore, the terms "including," "having," and any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or elements is not limited to the listed steps or elements, but may optionally include steps or elements not listed, or may optionally include other steps or elements inherent to the process, method, product, or apparatus.

[0039] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0040] Example 1

[0041] Example 1:

[0042] An active balancing device for a series battery pack includes a main control unit, a plurality of first communication units and a plurality of cell balancing units, wherein:

[0043] The first communication unit includes a cell information acquisition port, a balancing circuit connection port, and a main control unit connection port. The first communication unit collects cell information through the cell information acquisition port and transmits it to the main control unit through the main control unit connection port. The first communication unit transmits a power-taking instruction sent by the main control unit to the cell balancing unit through the balancing circuit connection port.

[0044] The cell balancing unit includes a first power supply port, through which power is taken from the total voltage of the series-connected battery pack to charge the cell; specifically, the cell balancing unit includes a cell balancing circuit, which is provided with the first power supply port.

[0045] The main control unit is communicatively connected to the first communication unit, and the main control unit includes a power supply module, which draws power from a total voltage port of the series-connected battery pack and transmits the power to the cell balancing unit through the first power supply port.

[0046] The battery information includes the voltage information and battery pack number of each battery pack connected in series, and the voltage information and battery cell number of each battery pack.

[0047] This solution uses an electric energy conversion method to achieve balancing, drawing power from the total voltage of the series battery pack, transferring the energy of the high-capacity battery cells to the low-capacity battery cells, and achieving full utilization of the battery pack cells.

[0048] Furthermore, the main control unit also includes a control module and a second communication unit, wherein,

[0049] The power supply module is electrically connected to the control module;

[0050] The control module is connected to the second communication unit, the second communication unit is connected to the first communication unit, and the control module communicates with the cell balancing unit and the cell through the first communication unit and the second communication unit.

[0051] Furthermore, the first communication unit includes a battery information acquisition module and a power-taking instruction interaction module, wherein the battery information acquisition module collects information of a single battery pack and information of each battery cell in the battery pack; the power-taking instruction interaction module is connected to the battery cell balancing unit and interacts power-taking instructions to the battery cell balancing unit, and the power-taking instructions include battery pack information and information of the battery cells that need to be charged in the battery pack.

[0052] In order to ensure stable charging, the main control unit further includes a main control isolation module, which is connected to the power supply module and the first power port of the cell balancing unit.

[0053] In other embodiments, the cell balancing unit includes a cell balancing circuit and a slave isolation module. The slave isolation module is provided with a first power port, which draws power from the main voltage port. It can be seen that the first power port is the primary port for drawing power from the main voltage port, and its location depends on the specific internal structure of the cell balancing unit. If the slave isolation module is not configured in the embodiment, the first power port is provided in the cell balancing circuit. If the slave isolation module is configured, the first power port is provided in the slave isolation module.

[0054] Referring to FIG1 , the battery pack active balancing device can be split into a master control unit 100 and several slave control units 200. The master control unit 100 includes a power supply module, a control module, a second communication unit, and a DC / DC master control isolation module. The power supply module also includes a step-down module, which includes a second power supply port that draws power from the total voltage port of the series-connected battery pack.

[0055] Several slave control units 200 are connected to several battery packs 300. In this embodiment, a "battery pack" comprises several battery cells connected in series. Each battery pack 300 is connected to a slave control unit. Each slave control unit 200 includes a first communication unit, a cell balancing unit, and a DC / DC slave isolation module. The cell balancing unit is connected to each cell within the battery pack 300 and includes a voltage balancing selection circuit that selects different cells for charging via a switching circuit. The cell balancing unit is connected to the total voltage port of the series-connected battery packs via a DC / DC slave isolation module to ensure stable voltage input.

[0056] Example 2:

[0057] Based on the active balancing device for series-connected battery packs disclosed in the above-mentioned embodiment 1, a method for active balancing of series-connected battery packs is further disclosed, including the following steps:

[0058] Step 10: The main control unit obtains battery information through the first communication unit;

[0059] Step 20: The main control unit determines whether the cell balancing condition is met based on the battery information. If so, the main control unit feeds back a power-up instruction to the cell balancing unit; if not, the main control unit waits to receive new battery information.

[0060] In step 30 , after receiving the power-taking instruction, the cell balancing unit takes power from the total voltage port of the series-connected battery pack through the first power-taking port to charge the corresponding cells that meet the cell balancing conditions.

[0061] An optional charging mode is further provided to achieve voltage balancing of each battery pack in the series battery pack and voltage balancing of each cell in the battery pack, as follows:

[0062] The step 20 further includes:

[0063] Step 21: When the voltage difference between the lowest battery pack voltage and the highest battery pack voltage in the current battery information obtained by the main control unit is greater than a threshold, the main control unit feeds back a power-off instruction to the cell balancing unit; the power-off instruction includes the battery pack information and the cell information in the corresponding battery pack;

[0064] Step 22: The cell balancing unit selects the cell with the lowest voltage in the battery pack with the lowest voltage according to the power extraction instruction, draws power through the first power extraction port, and charges the selected cell until the voltages of all cells in the selected battery pack are balanced.

[0065] In step 23, after completing the balancing of the internal cells of a group of battery packs, the main control unit waits to receive new battery information, and then repeats steps 21 to 22 until the voltage difference between the lowest battery pack voltage and the highest battery pack voltage is less than or equal to the threshold.

[0066] For example, there are N battery packs connected in series, namely S1-Sn. Each battery pack includes a number of battery cells. The number of battery cells in each battery pack is not limited and can be the same or different.

[0067] The battery information of each battery pack is collected in real time through the first communication unit. When the lowest and highest voltage differences among the N battery packs are greater than a threshold, the battery cell with the lowest voltage in the corresponding lowest battery pack (S1) is charged. S1 first completes a continuous charging process to achieve consistency among each battery cell inside, and then continues to compare the voltage information in S1-Sn. If S3 is the lowest at this time, the voltage of each battery cell inside S3 is first balanced according to the above method until the voltage difference of all battery packs collected by the first communication unit is less than or equal to the threshold, and then the balancing is terminated.

[0068] Battery information includes the voltage and pack number of each battery pack, as well as the voltage and cell number of each cell within each pack. After this information is fed back to the main control unit, the voltage difference between battery packs and within each pack can be determined based on the voltage and pack number of each battery pack, as well as the voltage difference of cells within each pack. Innovative balancing cycle logic is then used to ensure consistent balance across all cells within the pack and between packs.

[0069] Example 3:

[0070] A battery pack series system includes a plurality of battery packs 300 connected in series and the active balancing device for the series-connected battery packs disclosed in Example 1.

[0071] The battery pack series system also includes a total voltage port, which is electrically connected to the several battery packs connected in series and is used to output the total voltage of the battery packs connected in series; each of the battery packs includes several battery cells connected in series, each battery cell is electrically connected to the battery cell balancing unit, and the battery cell balancing unit is electrically connected to the total voltage port; the battery cell is communicatively connected to the main control unit through the first communication unit.

[0072] Among them, the battery information acquisition module and the power-taking instruction interaction module use an AFE analog front-end collector, which integrates acquisition and instruction interaction.

[0073] In actual production, the battery pack and the battery pack active balancing device can be produced separately, and then the interface can be configured to directly connect the two components electrically to complete the assembly of an overall product.

[0074] The specific embodiments described above further illustrate the objectives, technical solutions, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. In particular, it should be noted that any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included within the scope of protection of the present invention for those skilled in the art.

Claims

1. An active balancing device for a series-connected battery pack, characterized in that: It includes a main control unit, a plurality of first communication units and a plurality of cell balancing units, wherein: The first communication unit includes a cell information collection port, a balancing circuit connection port, and a main control unit connection port, wherein the first communication unit collects cell information through the cell information collection port and transmits the cell information to the main control unit through the main control unit connection port, and the first communication unit transmits the power-taking instruction sent by the main control unit to the cell balancing unit through the balancing circuit connection port; The cell balancing unit comprises a first power taking port, through which power is taken from a total voltage port of the series-connected battery pack to charge the cell; The main control unit is communicatively connected to the first communication unit, and the main control unit includes a power supply module, which draws power from the total voltage of the series-connected battery pack and transmits it to the cell balancing unit through the first power supply port.

2. The active balancing device for series connected battery packs according to claim 1, characterized in that: The main control unit also includes a control module and a second communication unit, wherein: The power supply module is electrically connected to the control module; The control module is connected to the second communication unit, the second communication unit is connected to the first communication unit, and the control module communicates with the cell balancing unit and the cell through the first communication unit and the second communication unit.

3. The active balancing device for series connected battery packs according to claim 1, characterized in that: The first communication unit includes a battery information acquisition module and a power extraction instruction interaction module, wherein: The battery information collection module collects information about the single battery pack and information about each battery cell in the battery pack; The power-taking instruction interaction module is connected to the cell balancing unit and exchanges power-taking instructions with the cell balancing unit. The power-taking instructions include battery pack information and information of cells in the battery pack that need to be charged.

4. The active balancing device for series connected battery packs according to any one of claims 1 to 3, characterized in that: The main control unit further includes a main control isolation module, and the main control isolation module is connected to the power supply module and the first power port of the battery cell balancing unit.

5. The active balancing device for series connected battery packs according to any one of claims 1 to 3, characterized in that: The cell balancing unit includes a slave isolation module and a cell balancing circuit. The slave isolation module is connected to the cell balancing circuit. The slave isolation module is connected to the first power supply port, and power is obtained from the total voltage port of the series-connected battery pack through the first power supply port.

6. The active balancing device for series connected battery packs according to any one of claims 1 to 3, characterized in that: The power supply module further includes a step-down module, and the step-down module includes a second power supply port, and the second power supply port draws power from the total voltage port of the series-connected battery pack.

7. A method for active balancing of series-connected battery packs, characterized in that: The active balancing device for a series-connected battery pack according to any one of claims 1 to 6 is used to implement the method, comprising the following steps: Step 10, the main control unit obtains battery information through the first communication unit; Step 20, the main control unit determines whether the cell balancing condition is met based on the battery information, and if so, feeds back to the cell balancing unit to obtain a power instruction; if not, the main control unit waits to receive new battery information; Step 30 , after receiving the power-drawing instruction, the cell balancing unit draws power from the total voltage port of the series-connected battery pack through the first power-drawing port to charge the corresponding cells that meet the cell balancing condition.

8. The active balancing method for series connected battery packs according to claim 7, characterized in that: The step 20 further includes: Step 21: When the main control unit obtains the current battery information, the voltage difference between the lowest battery pack voltage and the highest battery pack voltage is If the value is greater than the threshold, the main control unit feeds back a power-taking instruction to the battery cell balancing unit; the power-taking instruction includes the battery pack information and the battery cell information in the corresponding battery pack; Step 22, the cell balancing unit selects the cell with the lowest voltage in the battery pack with the lowest voltage according to the power taking instruction, takes power through the first power taking port, and charges the selected cell until the voltages of all cells in the selected battery pack are balanced; Step 23, after completing the balancing of the internal cells of a group of battery packs, the main control unit waits to receive new battery information, and then repeats steps 21-22 until the voltage difference between the lowest battery pack voltage and the highest battery pack voltage is less than or equal to the threshold.

9. A method for active balancing of series-connected battery packs according to claim 7 or 8, characterized in that: The battery information includes voltage information and battery pack number of each battery pack connected in series, and voltage information and battery cell number of each battery pack.

10. A battery pack series connection system, characterized in that: Comprising a plurality of battery packs connected in series and an active balancing device for the battery packs connected in series as claimed in any one of claims 1 to 6; The battery pack series connection system further includes a total voltage port, electrically connected to the plurality of battery packs connected in series, and configured to output a total voltage of the battery packs connected in series; Each of the battery packs includes a plurality of battery cells connected in series, each battery cell is electrically connected to the battery cell balancing unit, and the battery cell balancing unit is electrically connected to the total voltage port; the battery cell is communicatively connected to the main control unit via the first communication unit.

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