A series lithium battery internal resistance detection device and a battery management system

Abstract

The utility model provides a kind of series lithium battery internal resistance detection device and battery management system, the series lithium battery internal resistance detection device includes battery pack, switch array module, drive module, sampling resistance, AFE analog front end and MCU small system;The input end of the drive module is connected the first signal output pin of the MCU small system, and the output end of the drive module is connected the control end of the switch array module, and the input end of the switch array module is connected the battery pack, and the output end of the switch array module is connected the sampling resistance;The MCU small system is connected the sampling resistance and the AFE analog front end, and the AFE analog front end is used to collect the voltage information of the battery pack;The utility model can accurately identify the internal resistance of different aging degree battery cell, so as to facilitate subsequent accurate temperature correction.

Description

Technical Field

[0001] This utility model belongs to the field of lithium battery management technology, specifically relating to a series lithium battery internal resistance detection device and battery management system. Background Technology

[0002] Currently, lithium batteries are the energy storage technology with the best overall performance. Although there are still challenges such as cost, safety and resources, lithium batteries will remain the core pillar of the new energy industry in the future through breakthroughs in new materials, new systems and recycling technologies.

[0003] For a long time, lithium battery internal resistance testing has not only been a technical parameter measurement, but also the first line of defense for safety and a core basis for lifespan management. By regularly monitoring internal resistance, it is possible to: prevent faults such as thermal runaway; extend lifespan and optimize usage strategies; and reduce costs and minimize unplanned replacements.

[0004] Typically, the internal resistance of lithium batteries in energy storage systems is measured and matched by the manufacturer at the time of shipment, and cannot be measured again afterward. Therefore, conventional BMS systems do not have the capability to measure the internal resistance of lithium batteries. Although some BMS devices can estimate the internal resistance of lithium batteries by calculating based on the collected voltage and current data, the estimated value may have a large error, and the complex calculations require high computing power from the BMS device.

[0005] Furthermore, increased internal resistance is a major manifestation of battery aging. Aged batteries are more prone to overheating, have lower capacity, and are more likely to be fully charged or discharged. A single aging battery can significantly reduce the capacity of the entire energy storage system. Although the balancing function of the BMS can improve the situation to some extent, aging batteries can still create a vicious cycle, providing only temporary relief. Therefore, timely detection of battery internal resistance and timely assessment of battery aging status are essential. Currently, most solutions use battery discharge data to identify battery internal resistance through algorithms in the BMS system. Alternatively, a simpler solution is to directly read the battery internal resistance based on the battery's current state of charge (SOC), state of health (SOH), temperature, and rate capability. However, these solutions cannot accurately identify the internal resistance of batteries at different stages of aging or correct for temperature variations. Summary of the Invention

[0006] To address the shortcomings of the prior art, this invention provides a series lithium battery internal resistance detection device and battery management system, which can accurately identify the internal resistance of cells with different aging levels, so as to facilitate accurate temperature correction in the future.

[0007] In one aspect, this utility model provides a series lithium battery internal resistance detection device, including a battery pack, a switch array module, a drive module, a sampling resistor, an AFE analog front end, and an MCU small system; The input terminal of the drive module is connected to the first signal output pin of the MCU system, the output terminal of the drive module is connected to the control terminal of the switch array module, the input terminal of the switch array module is connected to the battery pack, and the output terminal of the switch array module is connected to the sampling resistor. The MCU system is connected to the sampling resistor and the AFE analog front end, which is used to collect the voltage information of the battery pack.

[0008] In some implementations, the battery pack includes a plurality of cells connected in series; The switch array module includes several sets of switch components; Each of the aforementioned battery cells is connected to a corresponding set of the aforementioned switch assemblies.

[0009] In some implementations, the switching assembly includes a first switching circuit and a second switching circuit; The input terminal of the first switching circuit is connected to the positive terminal of the battery cell, the output terminal of the first switching circuit is connected to the first terminal of the sampling resistor, and the control terminal of the first switching circuit is connected to the output terminal of the drive module. The input terminal of the second switching circuit is connected to the negative terminal of the battery cell, the output terminal of the second switching circuit is connected to the second terminal of the sampling resistor, and the control terminal of the second switching circuit is connected to the output terminal of the drive module.

[0010] In some implementations, the driving module includes at least one driving chip; The driver chip is used to receive control signals from the MCU system and drive one of the switch components to turn on.

[0011] In some implementations, The battery pack includes 16 cells connected in series. The driver chip is an EMB1428 chip, and there are three driver chips in total, which are cascaded together.

[0012] In some implementations, the MCU subsystem includes a first chip; The first chip is used to communicate with the AFE analog front end and the drive module, and to collect voltage information of the sampling resistor and calculate the cell internal resistance of the battery pack.

[0013] In some implementations, the MCU system further includes a differential amplifier circuit; The input terminal of the differential amplifier circuit is connected to the sampling resistor, and the output terminal of the differential amplifier circuit is connected to the first signal input pin of the first chip.

[0014] In some implementations, the first chip is a GD32F303RC chip.

[0015] In some implementations, the differential amplifier circuit includes a first operational amplifier, a first resistor, a second resistor, a third resistor, a fourth resistor, and a first capacitor; The first resistor is connected between the first pin and the fourth pin of the first operational amplifier, the second resistor is connected between the fourth pin of the first operational amplifier and the first end of the sampling resistor, the third resistor is connected between the third pin of the first operational amplifier and the second end of the sampling resistor, the fourth resistor is connected between the third pin of the first operational amplifier and the power supply terminal, and the first capacitor is connected between the third pin of the first operational amplifier and the ground terminal.

[0016] On the other hand, the present invention provides a battery management system, including a human-computer interaction module and the series lithium battery internal resistance detection device described in any of the above claims; The human-computer interaction module is connected to the MCU system via a communication interface.

[0017] In summary, this utility model has at least the following advantages: 1. This utility model provides a series lithium battery internal resistance detection device. It collects the voltage information of the battery pack through an AFE analog front end and drives the switching of the switch array module through an MCU microsystem control drive module. This allows the voltage information of different cells in the battery pack to be output to the sampling resistor through the switch array module. After the MCU microsystem collects the voltage information of the sampling resistor, it combines the voltage information collected by the AFE analog front end to calculate the internal resistance of each cell in the battery pack. It can accurately identify the internal resistance of cells with different aging levels, so as to facilitate accurate temperature correction in the future. Moreover, the circuit design of this series lithium battery internal resistance detection device is relatively simple and can be added to the circuit of the battery management system. It can detect the internal resistance of each cell in the battery pack online at any time without affecting its normal operation.

[0018] 2. The present invention provides a battery management system, including a series lithium battery internal resistance detection device, which can connect the MCU small system and the human-machine interaction module through a communication interface based on the internal resistance of each cell calculated by the series lithium battery internal resistance detection device, so as to realize accurate temperature correction of the cell in the future. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the internal resistance detection device for a series lithium battery provided in Embodiment 1 of this utility model; Figure 2-1 A schematic diagram of one of the driving module and switch array module provided in Embodiment 1 of this utility model; Figure 2-2 A second schematic diagram of the driving module and switch array module provided in Embodiment 1 of this utility model; Figure 2-3 A third schematic diagram of the driving module and switch array module provided in Embodiment 1 of this utility model; Figure 3 This is a schematic diagram of the MCU mini-system provided in Embodiment 2 of this utility model; Figure 4 This is a schematic diagram of the battery management system provided in Embodiment 3 of this utility model; Marked in the image: 100. Battery pack; 200. Switch array module; 300. Driver module; 400, sampling resistor; 500, AFE analog front end; 600, MCU small system. Detailed Implementation

[0020] To facilitate understanding of the present invention, a more comprehensive description will be given below in conjunction with the accompanying drawings and specific embodiments. The drawings illustrate preferred embodiments of the invention. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0021] Please refer to the diagrams, where the same component symbols represent the same components. The principles of this application are illustrated by way of example implementation in a suitable computing environment. The following description is based on the specific embodiments of this application exemplified, and should not be construed as limiting other specific embodiments not detailed herein.

[0022] As used herein, the term "module" can refer to a software or hardware object that executes on the computing system. The various components, modules, engines, and services described herein can be implementations on the computing system. The apparatuses and methods described herein can be implemented in software or hardware, both of which are within the scope of this application.

[0023] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0024] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation", "connection" and "linkage" should be interpreted broadly. For example, they can be fixed connections, detachable connections, or integral connections; they can be mechanical connections, electrical connections, or connections that allow communication between them; they can be direct connections or indirect connections through an intermediate medium; they can be internal connections between two components or interactive relationships between two components.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0026] Example 1: Please see Figure 1 A series lithium battery internal resistance detection device includes a battery pack 100, a switch array module 200, a drive module 300, a sampling resistor 400, an AFE analog front end 500, and an MCU mini-system 600.

[0027] The input terminal of the drive module 300 is connected to the first signal output pin of the MCU system 600, the output terminal of the drive module 300 is connected to the control terminal of the switch array module 200, the input terminal of the switch array module 200 is connected to the battery pack 100, and the output terminal of the switch array module 200 is connected to the sampling resistor 400.

[0028] The drive module 300, under the control of the MCU subsystem 600, drives the switch array module 200 to perform switching operations. The switch array module 200 is a functional module that integrates multiple electronic switches to selectively connect, switch, or isolate multiple input or output signals. In this embodiment, the switch array module 200 can perform internal switching operations under the drive of the drive module 300 to output the voltage information of different cells in the battery pack 100 to the sampling resistor 400.

[0029] Specifically, the first signal output pin of the MCU mini-system 600 outputs a control signal to the drive module 300, which controls the drive module 300 to drive the switch array module 200 to perform corresponding switching, so that the switch array module 200 outputs the voltage information of the corresponding cell in the battery pack 100 to the sampling resistor 400.

[0030] The MCU system 600 is connected to the sampling resistor 400 and the AFE analog front-end 500. The AFE analog front-end 500 is used to collect the voltage information of the battery pack 100.

[0031] Specifically, the AFE analog front-end 500 can collect the voltage information of each cell in the battery pack 100 and send the cell voltage information to the MCU microsystem 600. After the MCU microsystem 600 collects the voltage information of the sampling resistor 400, it combines the voltage information collected by the AFE analog front-end 500 to calculate the internal resistance of each cell in the battery pack 100. It can accurately identify the internal resistance of cells with different aging levels, so as to facilitate accurate temperature correction in the future. Moreover, the circuit design of this series lithium battery internal resistance detection device is relatively simple and can be added to the circuit of the battery management system. Without affecting its normal operation, it can detect the internal resistance of each cell in the battery pack 100 online at any time.

[0032] In some embodiments, the battery pack 100 includes a plurality of cells connected in series; the switch array module 200 includes a plurality of switch assemblies; and the plurality of cells are connected one-to-one with the plurality of switch assemblies.

[0033] The total voltage of the series-connected battery pack 100 is the sum of the voltages of each cell. However, simply detecting the total voltage cannot accurately calculate the internal resistance of cells with different aging levels. Therefore, in this embodiment, multiple sets of switching components are connected one-to-one with multiple cells. These multiple sets of switching components can be turned on or off under the driving action of the drive module 300. For example, under the control of the MCU mini-system 600, the drive module 300 drives the second set of switching components to turn on, and the second set of switching components is connected to the second cell. Therefore, when the second set of switching components is turned on, the voltage information of the second cell can be transmitted to the sampling resistor 400 through the second set of switching components. Then, the MCU mini-system 600 collects the voltage information of the sampling resistor 400. In addition, combined with the voltage information of the second cell in the battery pack 100 collected by the AFE analog front end 500, the internal resistance of the second cell is calculated.

[0034] Furthermore, the switching assembly includes a first switching circuit and a second switching circuit; the input terminal of the first switching circuit is connected to the positive terminal of the battery cell, the output terminal of the first switching circuit is connected to the first terminal of the sampling resistor 400, and the control terminal of the first switching circuit is connected to the output terminal of the drive module 300.

[0035] The input terminal of the second switching circuit is connected to the negative terminal of the battery cell, the output terminal of the second switching circuit is connected to the second terminal of the sampling resistor 400, and the control terminal of the second switching circuit is connected to the output terminal of the drive module 300.

[0036] If only the voltage at one end of the battery cell is collected, a huge error will occur due to the ground potential offset. However, by collecting the signals at both ends of the battery cell and calculating the difference, the influence of the ground potential offset can be completely offset. That is, no matter where the battery cell is located in the series circuit, the potential difference between the two poles is always its true voltage. Therefore, in this embodiment, by setting a first switching circuit connected to the positive pole of the battery cell and setting a second switching circuit connected to the negative pole of the battery cell, the signals at both ends of the battery cell are transmitted to the sampling resistor 400 through the first and second switching circuits. Then, the MCU system 600 collects the voltage information of the sampling resistor 400 to obtain the voltage information of the battery cell.

[0037] In some implementations, the drive module 300 includes at least one drive chip; the drive chip is used to receive control signals from the MCU subsystem 600 and drive one of the sets of switching components to turn on.

[0038] Furthermore, in one example, the battery pack 100 includes 16 cells connected in series; the driver chip is an EMB1428 chip, and there are three driver chips cascaded together, as shown in the reference. Figure 2-1 , Figure 2-2 and Figure 2-3 The three driver chips are U15B, U18B and U11B.

[0039] Since the EMB1428 chip has a limited number of pins, a single EMB1428 chip cannot drive the corresponding switching components of 16 battery cells. Therefore, based on the actual number of battery cells and the selected number of pins of the EMB1428 chip, the number of EMB1428 chips is set to 3.

[0040] The specific model of the EMB1428 chip can be either EMB1428QSQ or EMB1428NOPB. Of course, this embodiment does not impose specific limitations on the selection of the driver chip, and adjustments can be made according to actual needs.

[0041] For ease of understanding, the appendix is ​​provided here. Figure 2-1Taking the second battery cell B1 as an example, when it is necessary to detect the internal resistance of the second battery cell B1, the MCU system 600 first sends a control signal to the driver module 300 via SPI. The driver module 300 controls the switching components connected to the second battery cell B1 to turn on. Specifically, the first switching circuit connected to the positive terminal of the second battery cell B1 includes MOSFETs Q40B and Q32B, and the second switching circuit connected to the negative terminal of the second battery cell B1 includes MOSFETs Q42B and Q28B. That is, under the control of the driver module 300, MOSFETs Q40B, Q32B, Q42B, and Q28B are turned on, thus enabling the second battery cell to... The voltage signal is transmitted to the PLUS and MINUS terminals, which are connected to the sampling resistor 400, i.e., the two ends of R129. The sampling resistor 400 receives the cell voltage information transmitted from the switching component. The MCU system 600 uses its internal signal conditioning circuit and ADC to collect the voltage information on the sampling resistor 400. Combined with the voltage information of the second cell in the battery pack 100 collected by the AFE analog front end 500, the internal resistance of the second cell is calculated. Similarly, for the calculation process of the internal resistance of other cells, the MCU system 600 sends the corresponding control signal to the drive module 300, so that the drive module 300 controls the corresponding switching component to conduct.

[0042] For example, let the initial voltage of the nth cell be V. n0 The current is I when the switching assembly switches it to the sampling resistor 400Ω. n0 After a period of time, such as 1 second, the voltage of this battery cell is V. n The current is I n Then the internal resistance of the nth cell is R. n =(V n0 -V n ) / (I n -I n0 The current I flowing through the sampling resistor 400Ω, i.e., R129, is... n =V R129 / R129, I n0 =V' R129 / R129, where the value of the sampling resistor R129 is known, V R129 and V' R129 Data is collected using the MCU mini-system 600.

[0043] Example 2: This embodiment is a further optimization based on Embodiment 1. Please refer to the following: Figure 1 Based on the above, refer to Figure 3 .

[0044] In this embodiment, the MCU subsystem 600 includes a first chip U7; the first chip U7 is used to communicate with the AFE analog front-end 500 and the drive module 300, and to collect voltage information of the sampling resistor 400 and calculate the cell internal resistance of the battery pack 100.

[0045] Specifically, the first chip U7 is used to communicate with the AFE analog front-end 500 to collect the voltage information of the cells in the battery pack 100. The first chip U7 also communicates with the drive module 300 to output control signals, which cause the drive module 300 to drive the switch array module 200 to switch, so that the voltage information of the cells in the battery pack 100 is transmitted to the sampling resistor 400. The first chip U7 collects the voltage information of the sampling resistor 400 and calculates it in combination with the voltage information of the cells in the battery pack 100 collected by the AFE analog front-end 500, thereby obtaining the relevant cell internal resistance.

[0046] Furthermore, the MCU system 600 also includes a differential amplifier circuit; the input of the differential amplifier circuit is connected to the sampling resistor 400, and the output of the differential amplifier circuit is connected to the first signal input pin of the first chip U7.

[0047] Specifically, the first chip U7 is a GD32F303RC chip, and the output of the differential amplifier circuit is connected to the PA1 pin of the first chip U7.

[0048] In some implementations, the differential amplifier circuit includes a first operational amplifier U8, a first resistor R44, a second resistor R45, a third resistor R47, a fourth resistor R48, and a first capacitor C28.

[0049] Specifically, the first resistor R44 is connected between the first pin and the fourth pin of the first operational amplifier U8, the second resistor R45 is connected between the fourth pin of the first operational amplifier U8 and the first terminal of the sampling resistor 400R129, the third resistor R47 is connected between the third pin of the first operational amplifier U8 and the second terminal of the sampling resistor 400R129, the fourth resistor R48 is connected between the third pin of the first operational amplifier U8 and the power supply terminal, and the first capacitor C28 is connected between the third pin of the first operational amplifier U8 and the ground terminal.

[0050] A differential amplifier circuit is constructed using the first operational amplifier U8, the first resistor R44, the second resistor R45, the third resistor R47, the fourth resistor R48, and the first capacitor C28 to adjust the cell voltage information, facilitating acquisition by the ADC inside the MCU system 600.

[0051] Example 3: This embodiment further optimizes the structure based on Embodiment 1. Please refer to [link / reference]. Figure 4 .

[0052] On the other hand, the present invention provides a battery management system, which includes a human-computer interaction module and a series lithium battery internal resistance detection device as described in Embodiment 1 or Embodiment 2.

[0053] The human-machine interaction module is connected to the MCU subsystem 600 through a communication interface. After the MCU subsystem 600 calculates the internal resistance of each cell, it can transmit the data to the human-machine interaction module through the communication interface. The human-machine interaction module has display and operation functions and can send preset working modes to the MCU subsystem 600 based on the internal resistance of each cell calculated by the MCU subsystem 600, such as temperature correction of the cells.

[0054] The above description is merely an example and illustration of the structure of this invention, and while the description is specific and detailed, it should not be construed as limiting the scope of this invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this invention, and these obvious substitutions all fall within the protection scope of this invention.

Claims

1. A series lithium battery internal resistance detection device, characterized in that, This includes the battery pack, switch array module, drive module, sampling resistor, AFE analog front end, and MCU minisystem; The input terminal of the drive module is connected to the first signal output pin of the MCU system, the output terminal of the drive module is connected to the control terminal of the switch array module, the input terminal of the switch array module is connected to the battery pack, and the output terminal of the switch array module is connected to the sampling resistor. The MCU system is connected to the sampling resistor and the AFE analog front end, which is used to collect the voltage information of the battery pack.

2. The series lithium battery internal resistance detection device according to claim 1, characterized in that, The battery pack includes several cells connected in series; The switch array module includes several sets of switch components; Each of the aforementioned battery cells is connected to a corresponding set of the aforementioned switch assemblies.

3. The series lithium battery internal resistance detection device according to claim 2, characterized in that, The switching assembly includes a first switching circuit and a second switching circuit; The input terminal of the first switching circuit is connected to the positive terminal of the battery cell, the output terminal of the first switching circuit is connected to the first terminal of the sampling resistor, and the control terminal of the first switching circuit is connected to the output terminal of the drive module. The input terminal of the second switching circuit is connected to the negative terminal of the battery cell, the output terminal of the second switching circuit is connected to the second terminal of the sampling resistor, and the control terminal of the second switching circuit is connected to the output terminal of the drive module.

4. The series lithium battery internal resistance detection device according to claim 2, characterized in that, The driving module includes at least one driving chip; The driver chip is used to receive control signals from the MCU system and drive one of the switch components to turn on.

5. The series lithium battery internal resistance detection device according to claim 4, characterized in that, The battery pack includes 16 cells connected in series. The driver chip is an EMB1428 chip, and there are three driver chips in total, which are cascaded together.

6. The series lithium battery internal resistance detection device according to claim 1, characterized in that, The MCU subsystem includes a first chip; The first chip is used to communicate with the AFE analog front end and the drive module, and to collect voltage information of the sampling resistor and calculate the cell internal resistance of the battery pack.

7. The series lithium battery internal resistance detection device according to claim 6, characterized in that, The MCU subsystem also includes a differential amplifier circuit; The input terminal of the differential amplifier circuit is connected to the sampling resistor, and the output terminal of the differential amplifier circuit is connected to the first signal input pin of the first chip.

8. The series lithium battery internal resistance detection device according to claim 6 or 7, characterized in that, The first chip is a GD32F303RC chip.

9. The series lithium battery internal resistance detection device according to claim 7, characterized in that, The differential amplifier circuit includes a first operational amplifier, a first resistor, a second resistor, a third resistor, a fourth resistor, and a first capacitor; The first resistor is connected between the first pin and the fourth pin of the first operational amplifier, the second resistor is connected between the fourth pin of the first operational amplifier and the first end of the sampling resistor, the third resistor is connected between the third pin of the first operational amplifier and the second end of the sampling resistor, the fourth resistor is connected between the third pin of the first operational amplifier and the power supply terminal, and the first capacitor is connected between the third pin of the first operational amplifier and the ground terminal.

10. A battery management system, characterized in that, Includes a human-computer interaction module and a series lithium battery internal resistance detection device as described in any one of claims 1-9; The human-computer interaction module is connected to the MCU system via a communication interface.

Images