Lithium battery protection board with buck-boost function

Abstract

The invention discloses a lithium battery protection board with a buck-boost function, which comprises an anti-sparking circuit, a charge-discharge switch circuit, a bidirectional power converter and a battery management system, and is characterized in that the bidirectional power converter is used for boosting or reducing the voltage of a battery, and the current can flow bidirectionally to discharge or charge the battery; the charging and discharging switch circuit has a protection effect on charging and discharging of a battery, and the anti-sparking circuit is used for preventing a connecting terminal from being burnt out due to a sparking phenomenon caused by instant large current impact at an output end; and the battery management system is responsible for information acquisition, safety protection, work optimization and SOC and SOH calculation of the battery, controls the anti-sparking circuit and the charging and discharging switching circuit, and performs information exchange with the bidirectional power converter to ensure safe and reliable work of the system. The lithium battery protection plate can directly utilize the battery module or the whole pack, so that the cascade utilization efficiency of the battery is greatly improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium battery management and protection, and particularly relates to a lithium battery protection board with buck-boost function. Background Art

[0002] With the emergence of lithium batteries, battery cells are connected in series to form a certain DC voltage for external electrical equipment. Common examples include lithium batteries for electric two-wheelers, electric three-wheelers, special vehicles, etc. For the battery voltage in this application field, the voltage requirements are generally relatively fixed, such as 24V, 48V, 64V, etc., and the voltage of a single lithium battery cell is also basically fixed. For example, the nominal voltage of lithium iron phosphate is 3.2V. Therefore, a 48V battery requires 15 strings, a 64V battery requires 20 strings, etc. For a 48V - 40Ah battery, 15 strings of 40Ah battery cells need to be connected in series.

[0003] With the rapid development of electric vehicles and energy storage, the cascade utilization of lithium batteries has become a new development direction. However, the battery modules applied in this field vary greatly, and it is difficult to directly utilize the whole pack. It must be disassembled into independent battery cells and then recombined into corresponding battery packs according to requirements for reuse. This problem mainly stems from multiple aspects such as the inconsistency of battery performance, safety issues, economic costs, and technical challenges:

[0004] 1. Inconsistency of battery performance.

[0005] During the cascade utilization process of lithium batteries, due to various factors affecting the batteries during use, such as the number of charge and discharge cycles, usage environment, etc., the performance of the batteries gradually decays. The performance differences between different batteries are relatively large, and even batteries of the same batch may have significant performance differences. This inconsistency makes it difficult to directly apply the whole pack of batteries during cascade utilization because each battery needs to be individually detected and screened to ensure that its performance meets the requirements of specific applications.

[0006] 2. Safety issues.

[0007] There are potential safety hazards during the cascade utilization of lithium batteries. Since the batteries have experienced a certain number of charge and discharge cycles, their internal structures may change, such as a reduction in electrolyte, damage to the separator, etc., which may lead to safety problems such as short circuits and overheating during the cascade utilization process. In addition, there are also differences in safety between different brands and models of batteries, further increasing the difficulty of cascade utilization.

[0008] 3. Economic costs.

[0009] The economic cost of directly using the whole battery pack is also a factor that needs to be considered: on the one hand, for second-life utilization, steps such as battery detection, screening, and recombination are required, all of which demand a large amount of manpower, material resources, and financial resources; on the other hand, due to the inconsistency of battery performance and safety issues, the efficiency and reliability of the whole battery pack during second-life utilization may not meet expectations, thus reducing its economic value.

[0010] 4. Technical Challenges

[0011] Accurately estimating the remaining capacity: Under the offline state and inconsistency of the battery, accurately estimating the remaining capacity of retired lithium batteries is a technical challenge, which greatly affects the classification and screening efficiency of second-life utilization.

[0012] Disassembly technology: There are significant differences in the disassembly of batteries of different brands and types, lacking a consistent disassembly technology; in addition, harmful substances may be generated during the battery disassembly process, and effective environmental protection measures need to be taken.

[0013] Recombination technology: Recombining the selected batteries to form a new battery pack is also a technical challenge, which requires ensuring that the recombined battery pack meets the requirements of specific applications in terms of performance, safety, and reliability. Summary of the Invention

[0014] For application fields that require lithium batteries as backup power or energy storage and need to step up or step down the battery voltage to meet the use of the external system, the present invention provides a lithium battery protection board with step-up and step-down functions, which can directly utilize the battery in modules or as a whole pack without the need to disassemble it into individual cells and recombine them again, greatly improving the second-life utilization efficiency of the battery.

[0015] A lithium battery protection board with step-up and step-down functions, comprising:

[0016] A bidirectional power converter, used for stepping up or stepping down the voltage of the lithium battery pack, enabling bidirectional current flow to meet the charging and discharging requirements of the lithium battery;

[0017] A charge and discharge switch circuit, used for controlling the charge and discharge of the lithium battery pack. Once a fault occurs during the charge and discharge process, the power circuit is immediately cut off under the control instruction, thereby protecting the battery and power devices;

[0018] An anti-spark circuit, used to suppress the output current impact of the lithium battery pack to prevent the lithium battery voltage from being directly applied to an external capacitive load and generating a sparking phenomenon;

[0019] The battery management system is used to control the bidirectional power converter, manage the health of the battery cells in the lithium battery pack, control the charge and discharge switch circuit and the anti-spark circuit, and control the lithium battery pack to work in various working states through external information interaction, so as to achieve efficient operation and minimum power consumption.

[0020] Further, one side of the bidirectional power converter is connected to the lithium battery pack, and the other side is connected to an external device; the charge and discharge switch circuit is arranged on the connection loop between the bidirectional power converter and the lithium battery pack or on the connection loop between the bidirectional power converter and the external device.

[0021] Further, the anti-spark circuit includes a diode D with a one-way rectification function and a resistor R for suppressing current impact. The cathode of the diode D is connected in series with the resistor R; when the output terminal of the lithium battery protection board is connected to an external electrical device, the lithium battery voltage is applied to the external electrical device through the resistor R on the anti-spark circuit. Due to the existence of the resistor R, the current rises slowly, achieving the suppression of a large current impact, which can protect the output terminal from being burned black by a large current, thus achieving the purpose of anti-spark.

[0022] Further, the anti-spark circuit is arranged on the connection loop between the bidirectional power converter and the lithium battery pack or on the connection loop between the bidirectional power converter and the external device, and can also be connected in parallel with the charge and discharge switch circuit.

[0023] Further, the charge and discharge switch circuit is composed of two back-to-back switching tubes Qc and Qd connected in series; during charging, Qc is turned on to charge the lithium battery pack; during discharging, Qd is turned on to discharge the lithium battery pack; once a fault occurs during the charge and discharge process, the battery management system will quickly control the charge and discharge switch circuit to turn off the corresponding switching tube.

[0024] Further, the bidirectional power converter includes an inductor L1 and two switching tubes Q1 and Q2. Among them, L1, Q1, and Q2 together form a half-bridge topology structure to achieve step-up or step-down conversion of the lithium battery pack; when charging the lithium battery pack, Q2 is used as the main power tube, and Q1 is the synchronous tube; when discharging the lithium battery pack, Q1 is used as the main power tube, and Q2 is the synchronous tube.

[0025] Further, the battery management system receives external information and controls the operating state of the bidirectional power converter according to the external power demand, the cell condition of the lithium battery pack, and the actual operating capacity of the bidirectional power converter: when external energy is required, while ensuring that the lithium battery pack is in a dischargeable state, the battery management system controls the bidirectional power converter to release energy externally and sets the output voltage and maximum discharge current; when the lithium battery pack is in a rechargeable state and there is external power, the battery management system controls the bidirectional power converter to charge the lithium battery pack and sets the charging current and maximum charging voltage; when there is no external energy demand, the battery management system controls the bidirectional power converter to enter the standby state to reduce system power consumption.

[0026] Further, during the charging or discharging process of the lithium battery pack, the battery management system monitors the operating state of each cell in the lithium battery pack in real time and controls the bidirectional power converter according to the state information to ensure that the lithium battery pack operates in the best environmental conditions.

[0027] Further, the state information includes the voltage information, current information, and temperature information of the cells. The battery management system ensures that the voltage of the lithium battery pack is within a reasonable operating range based on the single-cell voltage and the overall voltage of the cells. At the same time, the SOC (State of Charge) and SOH (State of Health) of the cells are calculated based on the voltage and current information of the cells to obtain the health status of the cells, and the charging and discharging parameters of the cells are assisted to be optimized and ensured to operate in the best environmental conditions according to the temperature information of the cells.

[0028] Regarding the application of energy storage batteries, the present invention integrates power electronics technology, battery management technology, communication technology, and heat dissipation technology. Through these technologies, the present invention can expand the application of cells to different voltage platforms, or different cells to the same voltage platform, especially can apply large cells to the field of small-capacity battery packs. At the same time, through the present invention, retired batteries can be directly utilized in modules or as a whole package without being disassembled into cells and recombined again, greatly improving the cascade utilization efficiency of retired batteries. Therefore, the present invention has the following beneficial technical effects:

[0029] 1. When the protection board of the present invention is installed at the battery pack terminal, the occurrence of arcing can be effectively avoided, thereby extending the service life of the terminal.

[0030] 2. The protection board of the present invention can boost the voltages of batteries with different numbers of strings into a standard bus voltage, thereby expanding the usage scope of the cells.

[0031] 3. Chargers with different output voltages can complete the charging of the battery through the protection board of the present invention.

[0032] 4. The protection board of the present invention can be effectively applied to the second-life battery module to improve the second-life utilization efficiency.

[0033] 5. The protection board of the present invention can extend the service life of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic diagram of the overall structure of the lithium battery protection board of the present invention.

[0035] Figure 2 It is a schematic diagram of the connection of each functional module in the lithium battery protection board of the present invention.

[0036] Figure 3 It is a schematic diagram of the connection of the composition structure of the lithium battery protection board in the first embodiment of the present invention.

[0037] Figure 4 It is a schematic diagram of the connection of the composition structure of the lithium battery protection board in the second embodiment of the present invention.

[0038] Figure 5 It is a schematic diagram of the connection of the composition structure of the lithium battery protection board in the third embodiment of the present invention.

[0039] Figure 6 It is a schematic diagram of the connection of the composition structure of the lithium battery protection board in the fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0040] In order to describe the present invention more specifically, the technical solutions of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0041] As Figure 1 shown, the lithium battery protection board with buck-boost function of the present invention includes an anti-spark circuit, a charge-discharge switch circuit, a bidirectional power converter, and a battery management system. Among them, the anti-spark circuit is a current impact suppression circuit to prevent the lithium battery voltage from being directly applied to the external capacitive load and generating a spark phenomenon; the charge-discharge switch circuit is a circuit for controlling the charging or discharging of the lithium battery according to system requirements. During the charging and discharging process, once a problem occurs, it can disconnect the main power; the bidirectional power converter is a power conversion unit that can increase or decrease the lithium battery voltage and allow the current to flow bidirectionally to meet the charging and discharging requirements of the lithium battery; in addition to the lithium battery management functions of a conventional protection board, such as being responsible for lithium battery information acquisition, protection, SOC and SOH calculation, balancing, etc., the battery management system also needs to control the anti-spark circuit and the charge-discharge switch circuit, and in addition, it needs to interact with the bidirectional power converter to achieve system functions.

[0042] As Figure 2As shown, the anti-spark circuit is placed between the positive pole of the lithium battery and the output positive terminal. It effectively suppresses the impact current generated by the sudden application of the lithium battery voltage to the external capacitive load through the circuit internal resistance, and effectively avoids the sparking phenomenon caused by the connection between the output positive terminal and the external device. The anti-spark circuit is composed of a diode D with a one-way rectification function and a resistor R for suppressing the impact current in series. When the output terminal is connected to an external electrical device, the lithium battery voltage is applied to the external electrical device through the resistor R. Due to the existence of the resistor R, the current rises slowly, achieving the suppression of a large current impact, protecting the output terminal from being burned black by the large current, and thus achieving the purpose of anti-sparking.

[0043] The charge and discharge switch circuit places the bidirectional switch tube between the lithium battery and the bidirectional power converter. According to the system requirements, the charge switch tube is turned on to charge the lithium battery, or the discharge switch tube is turned on to discharge the lithium battery externally; during the charge and discharge process, if any fault occurs, the charge and discharge switch circuit is immediately disconnected. The charge and discharge switch circuit is composed of two back-to-back switch tubes (Qc and Qd) in series. During charging, Qc is turned on to charge the lithium battery; during discharging, Qd is turned on to discharge the lithium battery; during the charge and discharge process, once an abnormality occurs, the corresponding switch tube will be quickly turned off.

[0044] The bidirectional power converter has the functions of voltage boosting and bucking and bidirectional current flow. It can realize boosting or bucking the lithium battery voltage and then outputting it to the external port, and charging or discharging the lithium battery through the bidirectional flow of current. The bidirectional power converter mainly consists of an inductor L1 and two switch tubes Q1 and Q2 to form a half-bridge topology to complete the buck-boost function of the lithium battery. When charging the lithium battery, Q2 is used as the switch tube, and Q1 is the synchronous tube; when discharging the lithium battery, Q1 is used as the switch tube, and Q2 is the synchronous tube.

[0045] The battery management system has the functions of a conventional protection board, including cell information acquisition, protection, current sharing, SOC and SOH calculation, external communication, etc. At the same time, according to the external charging or discharging requirements, it controls the charge and discharge switch circuit to charge or discharge the lithium battery; according to the lithium battery voltage and external device requirements, it controls the bidirectional power converter to achieve voltage boosting and bucking and bidirectional current flow.

[0046] Embodiment 1

[0047] As Figure 3As shown in the figure, in this embodiment, the lithium battery protection board includes an anti-spark circuit, a charge and discharge switch circuit, a bidirectional power converter, and a battery management system. One end of the anti-spark circuit is connected to the positive electrode of the lithium battery, and the other end of the anti-spark circuit is connected to the positive terminal of the DC side of the bidirectional power converter. One end of the charge and discharge switch circuit is connected to the negative electrode of the lithium battery, and the other end of the charge and discharge switch circuit is connected to the negative terminal of the DC side of the bidirectional power converter. The other side of the bidirectional power converter is externally connected to an electrical device through an output terminal. The battery management system collects the state information of the lithium battery and controls the anti-spark circuit, the charge and discharge switch circuit, and the bidirectional power converter at the same time.

[0048] Embodiment Two

[0049] As Figure 4 shown in the figure, in this embodiment, the lithium battery protection board includes an anti-spark circuit, a charge and discharge switch circuit, a bidirectional power converter, and a battery management system. One end of the anti-spark circuit is connected to one end of the charge and discharge switch circuit and the positive electrode of the lithium battery, and the other end of the anti-spark circuit is connected to the other end of the charge and discharge switch circuit and the positive terminal of the DC side of the bidirectional power converter. The negative terminal of the DC side of the bidirectional power converter is connected to the negative electrode of the lithium battery. The other side of the bidirectional power converter is externally connected to an electrical device through an output terminal. The battery management system collects the state information of the lithium battery and controls the anti-spark circuit, the charge and discharge switch circuit, and the bidirectional power converter at the same time.

[0050] Embodiment Three

[0051] As Figure 5 shown in the figure, in this embodiment, the lithium battery protection board includes an anti-spark circuit, a charge and discharge switch circuit, a bidirectional power converter, and a battery management system. The positive terminal of the DC side of the bidirectional power converter is connected to the positive electrode of the lithium battery, and the negative terminal of the DC side of the bidirectional power converter is connected to the negative electrode of the lithium battery. The positive end of the other side of the bidirectional power converter is connected to one end of the anti-spark circuit, and the negative end of the other side of the bidirectional power converter is connected to one end of the charge and discharge switch circuit. The other end of the anti-spark circuit and the other end of the charge and discharge switch circuit are externally connected to an electrical device through an output terminal. The battery management system collects the state information of the lithium battery and controls the anti-spark circuit, the charge and discharge switch circuit, and the bidirectional power converter at the same time.

[0052] Embodiment Four

[0053] As Figure 6As shown in the figure, in this embodiment, the lithium battery protection board includes an anti-spark circuit, a charge and discharge switch circuit, a bidirectional power converter, and a battery management system. The positive terminal of the DC side of the bidirectional power converter is connected to the positive electrode of the lithium battery, and the negative terminal of the DC side of the bidirectional power converter is connected to the negative electrode of the lithium battery. The positive terminal of the other side of the bidirectional power converter is connected to one end of the anti-spark circuit and one end of the charge and discharge switch circuit. The other end of the anti-spark circuit is connected to the other end of the charge and discharge switch circuit, and then together with the negative terminal of the other side of the bidirectional power converter, an external electrical device is connected through an output terminal. The battery management system collects the state information of the lithium battery and simultaneously controls the anti-spark circuit, the charge and discharge switch circuit, and the bidirectional power converter.

[0054] The above description of the embodiments is to enable those of ordinary skill in the art to understand and apply the present invention. It is obvious that those skilled in the art can easily make various modifications to the above embodiments and apply the general principles described herein to other embodiments without creative labor. Therefore, the present invention is not limited to the above embodiments, and all improvements and modifications made by those skilled in the art based on the disclosure of the present invention should be within the protection scope of the present invention.

Claims

1. A lithium battery protection board with buck-boost function, characterized in that: include: Bidirectional power converter, used to step up or step down the voltage of lithium battery pack, so that the current flows in both directions to meet the charging and discharging requirements of lithium battery; The charge and discharge switch circuit is used to control the charge and discharge of the lithium battery pack. Once a fault occurs during the charge and discharge process, the control instruction immediately cuts off the power circuit, thereby protecting the battery and power devices; Anti-spark circuit, used to suppress the output current impact of lithium battery pack to prevent the lithium battery voltage from being directly applied to the external capacitive load and causing sparks; The battery management system is used to control the bidirectional power converter and manage the health of the battery cells in the lithium battery pack. It also controls the charge and discharge switch circuit and the anti-spark circuit. It controls the lithium battery pack to work in various working states through external information interaction, and achieves efficient operation and minimum power consumption.

2. The lithium battery protection board with buck-boost function according to claim 1, characterized in that: One side of the bidirectional power converter is connected to a lithium battery pack, and the other side is connected to an external device; the charge and discharge switch circuit is arranged on a connection loop between the bidirectional power converter and the lithium battery pack or on a connection loop between the bidirectional power converter and an external device.

3. The lithium battery protection board with buck-boost function according to claim 1, characterized in that: The anti-spark circuit includes a diode D with a unidirectional rectification function and a resistor R for suppressing current impact. The cathode of the diode D is connected in series with the resistor R. When the output terminal of the lithium battery protection board is connected to the external electrical equipment, the lithium battery voltage is added to the external electrical equipment through the resistor R on the anti-spark circuit. Due to the existence of the resistor R, the current rises slowly, thereby suppressing large current impacts and protecting the output terminal from being burned black due to large current, thereby achieving the purpose of anti-spark.

4. The lithium battery protection board with buck-boost function according to claim 2, characterized in that: The anti-spark circuit is arranged on a connection loop between the bidirectional power converter and the lithium battery pack or on a connection loop between the bidirectional power converter and an external device, and may also be connected in parallel with a charge and discharge switch circuit.

5. The lithium battery protection board with buck-boost function according to claim 1, characterized in that: The charge and discharge switch circuit is composed of two back-to-back switch tubes Qc and Qd connected in series; when charging, Qc is turned on to charge the lithium battery pack; when discharging, Qd is turned on to discharge the lithium battery pack; if a fault occurs during the charge and discharge process, the battery management system will quickly control the charge and discharge switch circuit to turn off the corresponding switch tube.

6. The lithium battery protection board with buck-boost function according to claim 1, characterized in that: The bidirectional power converter includes an inductor L1 and two switching tubes Q1 and Q2, wherein L1, Q1 and Q2 together form a half-bridge topology structure to achieve step-up or step-down conversion of a lithium battery pack; when charging the lithium battery pack, Q2 serves as the main power tube and Q1 is a synchronous tube; when discharging the lithium battery pack, Q1 serves as the main power tube and Q2 is a synchronous tube.

7. The lithium battery protection board with buck-boost function according to claim 1, characterized in that: The battery management system receives information from the outside, and controls the working state of the bidirectional power converter according to the external power demand and the cell condition of the lithium battery pack and the actual working capacity of the bidirectional power converter: when the external power is needed, the battery management system controls the bidirectional power converter to discharge energy and sets the output voltage and the maximum discharge current while ensuring that the lithium battery pack is in a dischargeable state; When the lithium battery pack is in a rechargeable state and there is an external power supply, the battery management system controls the bidirectional power converter to charge the lithium battery pack and sets the charging current and maximum charging voltage; when there is no external energy demand, the battery management system controls the bidirectional power converter to enter a standby state to reduce system power consumption.

8. The lithium battery protection board with buck-boost function according to claim 1, characterized in that: During the process of charging or discharging the lithium battery pack, the battery management system monitors the working status of each cell in the lithium battery pack in real time, and controls the bidirectional power converter according to the status information to ensure that the lithium battery pack works under the best environmental conditions.

9. The lithium battery protection board with voltage step-up and step-down function according to claim 8, characterized in that: The status information includes the voltage information, current information and temperature information of the battery cell. The battery management system ensures that the voltage of the lithium battery pack is within a reasonable working range based on the single cell voltage and the entire group voltage of the battery cell. At the same time, the SOC and SOH of the battery cell are calculated based on the voltage and current information of the battery cell to obtain the health status of the battery cell, and helps optimize the charging and discharging parameters of the battery cell based on the temperature information of the battery cell and ensure that it works under the best environmental conditions.

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