A multi-module battery pack structure and equalization method thereof

Abstract

The present invention belongs to the technical field of multi-module battery cell balancing, and specifically relates to a multi-module battery pack structure and a balancing method thereof, wherein a balancing device includes multiple cell modules, the cell modules are connected to a sampling unit, the sampling unit is connected to a control unit, and all control units are connected to the same communication bus; the sampling unit samples the state parameters of the cell modules, and multiple control units simultaneously send the corresponding state parameters to the communication bus, so that all control units receive the minimum state parameters on the communication bus, and control the balancing circuit according to the results of the comparative analysis to achieve the balancing of each corresponding cell module. The balancing device and balancing method in the present invention are based on a simple communication bus setting, and the control unit can quickly obtain the minimum state parameter during the balancing process, and each control unit independently controls the balancing of the cell modules, with faster response speed, stronger stability, lower performance requirements for the control system, and easy addition and removal of cell modules in the system.

Description

Technical Field

[0001] The present invention belongs to the technical field of multi-module battery cell balancing, and specifically relates to a multi-module battery pack structure and a balancing method thereof. Background Art

[0002] With the continuous development of battery energy storage technology, high-voltage, large-capacity battery packs are becoming more and more widely used. Due to the limitation of the number of front-end sampling and the need for convenient disassembly and assembly, high-voltage battery packs often adopt the form of multi-module series connection. In a multi-module battery pack, the imbalance between modules and between the cells of each module will affect the normal operation of the multi-module battery pack, resulting in reduced effective capacity, shortened battery pack life, reduced safety and reduced efficiency.

[0003] Generally speaking, high-voltage battery packs use a battery management system (BMS) to balance the modules and cells of the battery pack. The performance parameters of each cell are collected through a sensor network. The microcontroller in the battery management system periodically reads the performance parameters from the sensor, and then finds the modules and cells that need to be balanced through comparison and analysis, and controls the corresponding balancing circuit to adjust the balance. This balancing structure and method requires a high-performance battery management system to compare and analyze the collected performance parameters, which has a high implementation cost, and its balancing method is completely dependent on the battery management system, and has low stability. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the defects of the prior art multi-module battery pack balancing structure and method, which have high implementation cost and poor stability, thereby providing a multi-module battery pack structure and a balancing method thereof.

[0005] The present invention provides a method for balancing a multi-module battery pack. The balancing device includes a plurality of battery modules, each of which is connected to a sampling unit, each of which is connected to a control unit, and all of which are connected to the same communication bus. The balancing method includes the following method steps:

[0006] Step S1: All control units release the communication bus;

[0007] Step S2: transmitting a start signal on the communication bus;

[0008] Step S3: each of the control units receives the start signal and controls the corresponding sampling unit to sample the state parameters of the corresponding battery cell module; the control unit receives the state parameters, encodes them into parameter signals, and sends them to the communication bus at the same time;

[0009] Step S4: each of the control units receives a parameter signal from the communication bus and decodes it to form a minimum state parameter;

[0010] Step S5: each of the control units compares the state parameter obtained from the sampling unit with the minimum state parameter, and when the difference between the state parameter and the minimum state parameter is greater than the balancing threshold, performs a balancing operation for the corresponding battery cell module;

[0011] Step S6: When the difference between the state parameter and the minimum state parameter is smaller than the balancing threshold, the control unit stops the balancing operation.

[0012] Furthermore, in step S2, the main controller transmits a start signal on the communication bus, and the start signal is a low level signal.

[0013] Furthermore, the battery cell module includes multiple battery cells; in the step S3, the control unit receives the state parameters of the multiple battery cells, encodes the minimum state parameter therein to form a parameter signal and sends it to the communication bus; in the step S5, when the difference between the state parameter of the battery cell and the minimum state parameter is greater than the balancing threshold, the balancing operation is performed for the battery cells of the corresponding battery cell module.

[0014] Furthermore, in step S3, the control unit receives the state parameter and encodes it to form a parameter signal, which is in binary format and is output bit by bit from high to low on the communication bus, where "1" is output as a high level and "0" is output as a low level; when the control unit detects that the parameter signal output by itself is inconsistent with the parameter signal input on the communication bus, it stops outputting to the communication bus.

[0015] A multi-module battery pack structure includes a plurality of battery cell modules, and the balancing of the battery cell modules is achieved by the above-mentioned balancing method; it also includes a sampling unit, a control unit and a communication bus; each of the battery cell modules is connected to a sampling unit, and the sampling unit is used to sample the state parameters of the battery cell module; each of the sampling units is connected to a control unit, and the control unit is used to obtain the state parameters obtained by the sampling unit and realize sending and receiving communication with the communication bus.

[0016] Furthermore, it also includes a balancing unit, each of the battery cell modules is connected to one of the balancing units, and the corresponding control unit controls the balancing unit to adjust the state parameters of the corresponding battery cell module.

[0017] Furthermore, it also includes a low-voltage DC power supply, which is electrically connected to the communication bus through a pull-up resistor.

[0018] Furthermore, the control unit includes a signal output terminal and a signal input terminal, and the signal output terminal and the signal input terminal are respectively connected to the communication bus.

[0019] Furthermore, it also includes a main control module, which includes a drive unit and a main controller; the drive unit is connected to and drives each of the battery modules; the main controller is connected to and controls the drive unit and is connected to the communication bus.

[0020] Furthermore, each of the battery cell modules includes a plurality of battery cells.

[0021] Beneficial effects: The present invention discloses a multi-module battery pack structure and a balancing method thereof, wherein the balancing device comprises a plurality of battery cell modules, the battery cell modules are connected to a sampling unit, the sampling unit is connected to a control unit, and all control units are connected to the same communication bus; in the present invention, the sampling unit samples the state parameters of the battery cell modules, and a plurality of control units simultaneously send the corresponding state parameters to the communication bus, so that all control units receive the minimum state parameters on the communication bus, and control the balancing circuit according to the result of the comparative analysis to achieve the balancing of each corresponding battery cell module. The balancing device and balancing method in the present invention are based on a simple communication bus setting, and the control unit can quickly obtain the minimum state parameter during the balancing process, and each control unit independently controls the balancing of the battery cell modules, with faster response speed, stronger stability, lower performance requirements for the control system, and easy addition and removal of battery cell modules in the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 It is a schematic diagram of the method steps of the present invention;

[0024] Figure 2 It is a schematic block diagram of the overall structure of the present invention;

[0025] Figure 3 It is a schematic diagram of the communication bus connection structure of the present invention;

[0026] Figure 4 It is a communication timing diagram of the present invention;

[0027] Figure 5 It is a schematic diagram of the communication process of the present invention. DETAILED DESCRIPTION

[0028] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0029] In the description of the present application, it should be understood that, in addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present application, "plurality" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0030] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0031] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only implementation method.

[0032] Embodiment 1:

[0033] Reference Figure 2 and Figure 3 As shown, this embodiment discloses a multi-module battery pack structure, including multiple battery cell modules, and achieving balancing of the battery cell modules through the above-mentioned balancing method; it also includes a sampling unit, a control unit and a communication bus; each of the battery cell modules is connected to a sampling unit, and the sampling unit is used to sample the state parameters of the battery cell module; each of the sampling units is connected to a control unit, and the control unit is used to obtain the state parameters obtained by the sampling unit, and realize sending and receiving communication with the communication bus.

[0034] In this embodiment, the communication bus is a single-line bus, and the signal output terminal and the signal input terminal of each control unit are respectively connected to the single-line bus, the signal output terminal is recorded as D_out, and the signal input terminal is recorded as D_in. In this embodiment, three battery cell modules are provided, and multiple battery cells are provided in each battery cell module.

[0035] Specifically, it also includes a balancing unit, each of the battery modules is connected to one of the balancing units, and the corresponding control unit controls the balancing unit to adjust the state parameters of the corresponding battery module. It also includes a low-voltage DC power supply, which is shown as Vdd. The low-voltage DC power supply is electrically connected to the communication bus through a pull-up resistor to ensure that the bus can maintain a high level when idle. The control unit includes a signal output terminal and a signal input terminal, and the signal output terminal and the signal input terminal are respectively connected to the communication bus.

[0036] In some implementations of this embodiment, a main control module is further included, and the main control module includes a drive unit and a main controller; the drive unit is connected to and drives each of the battery modules; the main controller is connected to and controls the drive unit, and is connected to the communication bus. In this implementation, the main control module controls the charging, discharging and other BMS functions of the battery module. When implementing the balancing function, the main controller is used to send a start signal to the communication bus to coordinate the timing of all control units.

[0037] In some other implementations of this embodiment, one of the control units is selected to send a start signal to the communication bus, thereby coordinating the timing of all other control units.

[0038] In some implementations of this embodiment, each of the battery modules includes a plurality of battery cells. During sampling, the sampling unit obtains the state parameters of all battery cells in the corresponding battery module and sends them to the corresponding control unit, and the control unit sends the minimum state parameter to the data bus; during balancing, the control unit determines whether each of the battery cells needs balancing based on the minimum state parameter obtained, and controls the balancing unit to adjust the state parameters of the battery cells that need balancing.

[0039] In some other implementations of this embodiment, a battery cell is provided in each battery cell module. During sampling, the sampling unit obtains the state parameters of the battery cells of the corresponding battery cell module and sends them to the corresponding control unit, and the control unit sends the state parameters to the data bus; during balancing, the control unit determines whether the battery cells need to be balanced according to the minimum state parameters obtained, and controls the balancing unit to adjust the state parameters of the battery cells when balancing is required.

[0040] In this embodiment, the control unit and the main controller can be one or more of MCU, CPU, FPGA, single chip microcomputer. As a preferred embodiment of this embodiment, the control unit and the main controller are set as MCU to provide high performance and high reliability control for the balancing device.

[0041] Embodiment 2:

[0042] Reference Figure 1 As shown, this embodiment provides a balancing method for a multi-module battery pack. The structure of the multi-module battery pack is as described in the first embodiment. The balancing device includes a plurality of battery modules, each of which is connected to a sampling unit, each of which is connected to a control unit, and all of the control units are connected to the same communication bus. The balancing method includes the following method steps:

[0043] Step S0: Define the communication timing of the communication bus, refer to Figure 4 As shown, the basic time t b is the time to transmit one bit, the start signal length t s The shortest duration of the start signal, which is greater than 16t in this embodiment. b , conversion time t t is the conversion time between the signals. In this embodiment, the conversion time is less than one percent of t b , sampling time t m The time for sampling digital signals after the start signal is stable, and the idle time t i The waiting time after a frame ends and before the next frame transmission starts. The length is greater than 16t b .

[0044] Step S1: All control units release the communication bus; at this time, due to the presence of the low-voltage DC power supply, the level on the communication bus is high.

[0045] Step S2: Transmitting a start signal on the communication bus; In step S2, the main controller or one of the control units sends a start signal to the communication bus. In this embodiment, the main controller sends a start signal to the communication bus, and the start signal is greater than 16t b A low level signal.

[0046] Step S3: each of the control units receives the start signal and controls the corresponding sampling unit to sample the state parameters of the corresponding battery cell module; the control unit receives the state parameters, encodes them into parameter signals, and sends them to the communication bus at the same time;

[0047] Specifically, in step S3, each control unit receives a start signal, samples the state parameters and encodes them to form a binary parameter signal. After the start signal ends and the conversion time tt Then, the binary data is output bit by bit from high to low at the preset baud rate, where "1" is output as a high level and "0" is output as a low level; when the data input end of the control unit detects that the level on the communication bus is different from the level output by the data output end, the data output is stopped and the communication bus is released. When different control units output high and low levels on the communication bus at the same time, the high level is covered by the low level, so the higher output parameter signal is covered and the subsequent bits are stopped from being output, so that the final data transmitted on the communication bus is the smallest parameter signal.

[0048] Reference Figure 5 As shown, in this embodiment, the data to be sent by the first control unit is 3500, the corresponding hexadecimal is 0x0DAC, and the corresponding binary parameter signal is 0000 1101 1010 1100. The data to be sent by the second control unit is 3450, the corresponding hexadecimal is 0x0D7A, and the corresponding binary parameter signal is 0000 1101 0111 1010. The data to be sent by the third control unit is 3400, the corresponding hexadecimal is 0x0D48, and the corresponding binary parameter signal is 0000 1101 01001000. When the transmission reaches the seventh bit, the input and output of the first control unit are inconsistent, the first control unit no longer controls its data output end, and the transmission ends. When the transmission reaches the fifth bit, the input and output of the second control unit are inconsistent, the second control unit no longer controls its data output end, and the transmission ends. Thus, the third control unit completes the complete sixteen-bit parameter signal output on the communication bus.

[0049] In some implementations of this embodiment, the battery cell module includes a plurality of battery cells, and the control unit receives the state parameters of the plurality of battery cells, encodes the smallest state parameter therein to form a parameter signal and sends the parameter signal to a communication bus.

[0050] Step S4: each of the control units receives a parameter signal from the communication bus and decodes it to form a minimum state parameter;

[0051] Step S5: each of the control units compares the state parameter obtained from the sampling unit with the minimum state parameter, and when the difference between the state parameter and the minimum state parameter is greater than the balancing threshold, performs a balancing operation for the corresponding battery cell module;

[0052] Specifically, a preset threshold is set, and the control unit calculates the difference between the state parameter of the battery cell in the battery cell module and the minimum state parameter. When the difference is greater than the preset threshold, the balancing unit is controlled to perform a balancing operation for the corresponding battery cell of the corresponding battery cell module.

[0053] In some implementations of this embodiment, when the difference between the state parameter of the battery cell and the minimum state parameter is greater than a balancing threshold, a balancing operation is performed for the battery cells of the corresponding battery cell module.

[0054] Step S6: When the difference between the state parameter and the minimum state parameter is smaller than the balancing threshold, the control unit controls the balancing unit to stop the balancing operation.

[0055] In some embodiments of the present invention, the state parameter is the output voltage of the battery cell; in other embodiments of the present invention, the state parameter is the charge state of the battery cell.

[0056] Embodiment 1 and embodiment 2 disclose a multi-module battery pack structure and a balancing method thereof, wherein a balancing device includes multiple battery cell modules, the battery cell modules are connected to a sampling unit, the sampling unit is connected to a control unit, and all control units are connected to the same communication bus; in a specific implementation, the sampling unit samples the state parameters of the battery cell modules, and multiple control units simultaneously send the corresponding state parameters to the communication bus, so that all control units receive the minimum state parameters on the communication bus, and control the balancing circuit according to the results of the comparative analysis to achieve the balancing of each corresponding battery cell module. The balancing device and balancing method in this embodiment are based on a simple communication bus setting, and the control unit can quickly obtain the minimum state parameter during the balancing process, and each control unit independently controls the balancing of the battery cell modules, with faster response speed, stronger stability, lower performance requirements for the control system, and easy addition and removal of battery cell modules in the system.

[0057] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0058] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. A method for balancing a multi-module battery pack, characterized in that: The balancing device includes a plurality of battery modules, each of which is connected to a sampling unit, each of which is connected to a control unit, and all of which are connected to the same communication bus. The balancing method includes the following steps: Step S1: All control units release the communication bus; Step S2: transmitting a start signal on the communication bus; Step S3: each of the control units receives the start signal and controls the corresponding sampling unit to sample the state parameters of the corresponding battery cell module; the control unit receives the state parameters, encodes them into parameter signals, and sends them to the communication bus at the same time; In step S3, the control unit receives the state parameter and encodes it to form a parameter signal, the parameter signal is in binary format, and is output bit by bit from high to low on the communication bus, wherein "1" is output as a high level and "0" is output as a low level; when the control unit detects that the parameter signal output by itself is inconsistent with the parameter signal input on the communication bus, the output to the communication bus is stopped; Step S4: each of the control units receives a parameter signal from the communication bus and decodes it to form a minimum state parameter; Step S5: each of the control units compares the state parameter obtained from the sampling unit with the minimum state parameter, and when the difference between the state parameter and the minimum state parameter is greater than the balancing threshold, performs a balancing operation for the corresponding battery cell module; Step S6: When the difference between the state parameter and the minimum state parameter is smaller than the balancing threshold, the control unit stops the balancing operation.

2. A method for balancing a multi-module battery pack according to claim 1, characterized in that: In the step S2, the main controller transmits a start signal on the communication bus, and the start signal is a low level signal.

3. A method for balancing a multi-module battery pack according to claim 1, characterized in that: In step S3, the control unit receives the state parameter and encodes it to form a parameter signal, which is in binary format and is output bit by bit from high to low on the communication bus, where "1" is output as a high level and "0" is output as a low level; when the control unit detects that the parameter signal output by itself is inconsistent with the parameter signal input on the communication bus, it stops outputting to the communication bus.

4. A multi-module battery pack structure, comprising a plurality of battery cell modules, characterized in that: The balancing of the battery cell module is achieved by the balancing method described in any one of claims 1 to 3; it also includes a sampling unit, a control unit and a communication bus; each of the battery cell modules is connected to a sampling unit, and the sampling unit is used to sample the state parameters of the battery cell module; each of the sampling units is connected to a control unit, and the control unit is used to obtain the state parameters obtained by the sampling unit and realize sending and receiving communication with the communication bus.

5. A multi-module battery pack structure according to claim 4, characterized in that: It also includes a balancing unit, each of the battery cell modules is connected to one balancing unit, and the corresponding control unit controls the balancing unit to adjust the state parameters of the corresponding battery cell module.

6. A multi-module battery pack structure according to claim 4, characterized in that: It also includes a low-voltage DC power supply, which is electrically connected to the communication bus through a pull-up resistor.

7. A multi-module battery pack structure according to claim 4, characterized in that: The control unit comprises a signal output terminal and a signal input terminal, and the signal output terminal and the signal input terminal are respectively connected to the communication bus.

8. The multi-module battery pack structure according to claim 4, characterized in that: It also includes a main control module, which includes a drive unit and a main controller; the drive unit is connected to and drives each of the battery modules; the main controller is connected to and controls the drive unit and is connected to the communication bus.

9. The multi-module battery pack structure according to claim 4, characterized in that: Each of the battery cell modules includes a plurality of battery cells.

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