A battery equalization protection module with multiple usage modes

Abstract

The present invention discloses a battery equalization protection module with multiple usage modes, including a circuit interface and an equalization protection circuit. The circuit interface is divided into three groups and is welded on the circuit board of the equalization protection circuit and connected to the equalization protection circuit. The equalization protection circuit further includes: a main control unit, a temperature sampling circuit, a voltage detection circuit, a current sampling circuit, a flux coupling circuit, and an energy transfer circuit. Different groups of circuit interfaces are configured with different functions, enabling cascading and parallel connection between multiple equalization protection modules to achieve the application of the module to a lithium-ion battery pack composed of more than 24 single cells, high-current equalization scenarios, and communication with an external host computer.

Description

Technical Field

[0001] The present invention belongs to the technical field of battery pack equalization management, and particularly relates to a battery equalization protection module with multiple usage modes. Background Art

[0002] Lithium batteries are widely used in mobile and portable devices and electric vehicles due to their high energy density, low self-discharge, environmental friendliness, and long cycle life. Since lithium batteries are chemically active, overcharging, over-discharging, over-current discharging, or overheating during battery use can cause hazards such as battery explosion. Due to the small capacity and low load capacity of a single battery cell, to meet actual requirements, battery cells are combined into a lithium battery pack through a certain connection method. In a lithium battery pack, an important factor affecting the system life is the consistency of battery cells. Due to differences in operating temperature, battery capacity, internal resistance, and self-discharge among battery cells, as the number of charge and discharge cycles of the lithium battery pack increases, the differences among battery cells gradually differentiate, thereby leading to a decrease in the performance and shortening of the life of the lithium battery pack.

[0003] To solve the problems of overcharging, over-discharging, over-current discharging, overheating, and the consistency of battery cells during the use of a lithium battery pack, the Chinese utility model patent with the publication number "CN211063383U" in the prior art proposes a protection system for multi-string lithium batteries, and its solution is as follows: It includes a main control circuit, and a sampling and execution circuit is connected between the main control circuit and the lithium battery. The sampling and execution circuit includes a BQ76930 chip and the chip peripheral circuit. The chip peripheral circuit includes a sampling circuit and an execution circuit. The chip peripheral circuit is connected to the lithium battery. The sampling circuit collects lithium battery information and inputs it into the BQ76930 chip. The execution circuit receives the signal from the BQ76930 chip and controls the charge and discharge of the lithium battery by controlling the on / off of the MOS switch tube; this system has a hardware automatic protection function and an automatic equalization function by using the BQ76930 chip, and through cooperation with the peripheral circuit, it can effectively prevent overcharging and over-discharging of lithium batteries.

[0004] However, for lithium-ion battery packs composed of 24 or more single cells, the existing equalization protection modules require external circuit assistance during equalization, resulting in a complex overall structure and high cost. Additionally, when the single battery pack capacity reaches 20 Ah or even a larger capacity such as 200 Ah, in order to handle different battery capacities, the equalization module needs to redesign the parameters of the equalization protection circuit, increase the size of the equalization transformer, and select high-current power MOS switching tubes. In such applications, the equalization efficiency, overcurrent protection during equalization, heat loss, and temperature rise during the high-current equalization process are all technical difficulties, and the implementation technology is complex and costly. Moreover, the existing active equalization modules do not have a communication networking function and cannot accept instructions from the battery management unit (BMU) control system, such as starting equalization and stopping equalization, nor can they report the status of the equalization module (such as working status, fault conditions, etc.) to the BMU. Summary of the Invention

[0005] The present invention provides a battery equalization protection module with multiple usage modes, aiming to solve the problems in the prior art that the equalization protection module is limited to 24 single cells, does not support high-current equalization, and the equalization process is not intuitive enough for users.

[0006] To solve the above technical problems, the present invention provides a battery equalization protection module with multiple usage modes, and an external communication interface is set on the module to communicate with the host computer to send data and receive instructions. The specific solutions are as follows:

[0007] A battery equalization protection module with multiple usage modes includes a circuit interface and an equalization protection circuit. There are a total of 3 groups of the circuit interfaces, which are arranged on the circuit board of the equalization protection circuit and connected to the equalization protection circuit. Among them, the first group of circuit interfaces has several interfaces for connecting a lithium-ion battery pack; the second group of circuit interfaces has several interfaces for connecting the next-level equalization protection module in the cascaded usage scenario of the equalization protection module, or connecting the lithium-ion battery pack in the standalone usage scenario; the third group includes a grounding interface and a communication interface, and the communication interface is used for communicating with an external host computer;

[0008] The equalization protection circuit further includes: a main control unit, a communication circuit, a temperature sampling circuit, a voltage detection circuit, a current sampling circuit, and a magnetic flux coupling and energy transfer circuit; the main control unit is respectively connected to each circuit and receives signals transmitted by each circuit; the communication circuit is also connected to the third group of interface circuits of the circuit interface;

[0009] The flux coupling and energy transfer circuit includes a number of transformer coils. Each transformer coil has a leading pin, a trailing pin, and a middle pin led out. The middle pin is respectively connected to the positive electrode of each single cell in the lithium-ion battery pack through the first group and the second group of circuit interfaces. The leading pin and the trailing pin are respectively connected to the source and drain of the MOS transistor. The MOS transistor is circuit-connected to the first square-wave and second square-wave pins of the main control unit, and receives the square-wave signal of the main control unit to control the conduction or cut-off of the source and drain.

[0010] The main control unit receives the voltage signal of the sampling circuit, compares the voltage signal with the set threshold value, and issues start balancing, stop balancing, and current limiting instructions to the flux coupling and energy transfer circuit according to the comparison result.

[0011] Preferably, in the case of only using a group of balancing protection modules, the first group and the second group of interfaces of the circuit interface are sequentially connected to the two poles of each single cell in the lithium-ion battery pack. A total of 17 interfaces can be connected to a maximum of 16 single cells.

[0012] Preferably, when at least two balancing protection modules are used for a lithium-ion battery pack composed of more than 16 single cells, the second group of interfaces of each balancing protection module are respectively connected to the first five interfaces of the first group of interfaces of the next-level balancing protection module; that is, B12 is connected to the B0 interface of the next-level module, B13 is connected to the B1 interface of the next-level module, B14 is connected to the B2 interface of the next-level module, B15 is connected to the B3 interface of the next-level module, and B16 is connected to the B4 interface of the next-level module.

[0013] Preferably, when at least two groups of the balancing protection modules are used in parallel, the interfaces with the same number in the B0 to B16 interfaces of all the balancing protection modules are connected together and connected to the lithium-ion battery pack through a wiring board.

[0014] Preferably, the balancing protection module is connected to an external upper computer through a third group of interfaces, and is used to receive the control instructions of the upper computer and send the parameter information of the battery pack.

[0015] Preferably, the first group and the second group of the circuit interface have a total of 17 interfaces. The first interface in the first group of circuit interfaces is connected to the negative electrode of the lithium-ion battery pack in series with a resistor, and each of the other interfaces is connected to the positive electrode of each single cell in the lithium-ion battery pack in series with a resistor in sequence.

[0016] Preferably, the temperature sampling circuit samples the temperature through an NTC resistor closely attached to the lithium-ion battery pack and is connected to the temperature sampling pin of the main control unit.

[0017] Preferably, when the equalization protection modules are used in parallel, the current that the connection line between the wiring board and the lithium-ion battery pack can withstand should be greater than the sum of the currents that all the equalization modules can withstand.

[0018] Preferably, the connection between the equalization protection module and the wiring board is made by pluggable connection terminals.

[0019] Compared with the prior art, the present invention has the following technical effects:

[0020] 1. The equalization protection module proposed by the present invention has an equalization current protection function. The threshold of the equalization current protection can be set through the protection module of the module. When the sudden equalization current exceeds the threshold, the protection function is activated and the equalization circuit is cut off to protect the equalization module.

[0021] 2. On the basis of the equalization current protection function, for large-capacity battery packs that require large current equalization in actual applications, the equalization protection module proposed by the present invention can be used in parallel through the wiring board to adapt to the equalization current scenario exceeding 3A. For each additional parallel module, the equalization current of the battery pack doubles, and there is no upper limit to the number of parallel modules, effectively expanding the scope of use of the equalization protection template.

[0022] 3. When the equalization protection module proposed by the present invention equalizes a lithium-ion battery pack with more than 16 single battery cells, multiple equalization protection modules can be cascaded. Connect the B12 - B16 interfaces of the second group of each equalization protection module to the B0 - B4 interfaces of the first group of the next equalization protection module respectively. According to the number of equalization protection modules used in cascade, 12N + 4 single battery cells can be equalized and protected (N is the number of equalization protection modules in the cascade structure).

[0023] 4. The third group of circuit interfaces in the equalization protection module proposed by the present invention can be connected to an external host computer, which can be used to receive control commands and send parameter information, facilitating user intervention in the equalization protection process, and at the same time providing a human-computer interaction interface to display the parameters of the lithium-ion battery pack in real time. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a schematic structural diagram of a battery equalization protection module with multiple usage modes according to the present invention;

[0025] Figure 2 is a schematic diagram of a typical application of a battery equalization protection module with multiple usage modes according to the present invention;

[0026] Figure 3 is a wiring schematic diagram in the scenario of cascaded use of a battery equalization protection module with multiple usage modes according to the present invention;

[0027] Figure 4 It is a wiring schematic diagram in the parallel usage scenario of a battery equalization protection module with multiple usage modes according to the present invention;

[0028] Figure 5 It is a schematic circuit diagram of temperature sampling of a battery equalization protection module with multiple usage modes according to the present invention;

[0029] Figure 6 It is a schematic circuit diagram of current sampling of a battery equalization protection module with multiple usage modes according to the present invention;

[0030] Figure 7 It is a schematic diagram of the pins of the main control chip of a battery equalization protection module with multiple usage modes according to the present invention;

[0031] Figure 8 It is a schematic circuit diagram of magnetic flux coupling and energy transfer of a battery equalization protection module with multiple usage modes according to the present invention.

[0032] In the figure: 1. Equalization protection module; 2. Lithium-ion battery pack; 3. Protection board; 4. Host computer; 5. Wiring board; 11. Main control unit; 12. Circuit interface; 13. Magnetic flux coupling and energy transfer circuit; 14. Current sampling circuit; 15. Voltage detection circuit; 16. Temperature sampling circuit. Specific embodiments

[0033] To make the objectives, technical solutions and advantages of the present invention clearer, the following will combine specific embodiments of the present application and refer to the accompanying drawings to clearly and completely describe the technical solutions of the present invention.

[0034] A battery equalization protection module with multiple usage modes includes a circuit interface 12 and an equalization protection circuit. There are a total of 3 groups of circuit interfaces 12, which are arranged on the circuit board of the equalization protection circuit and connected to the equalization protection circuit. Among them, the first group of circuit interfaces has a total of 12 interfaces B0 to B11, and the second group of circuit interfaces has a total of 5 interfaces B12 to B16, which are used to connect the next-level equalization protection module 1 in the cascaded usage scenario of the equalization protection module 1. The third group has 2 interfaces, namely GND1 and EN, which are used to communicate with the external host computer 5;

[0035] The equalization protection circuit further includes: a main control unit 11, a communication circuit 17, a temperature sampling circuit 16, a voltage detection circuit 15, a current sampling circuit 14, and a magnetic flux coupling and energy transfer circuit 13; the communication line 17 is connected to the third set of interface circuits of the main control unit 11 and the circuit interface 12; the temperature sampling circuit 16 is connected to the VDD5V, SPI-1 / NTC, and BO / GND pin circuits of the main control unit 11, and converts the resistance value of the NTC resistor into a voltage signal and inputs it to the main control unit 11; the voltage detection circuit 15 is connected to the AD-IN-H and AD-IN-L pin circuits of the main control unit 11, and inputs the voltage signal of the lithium-ion battery pack into the main control unit 11; the current sampling circuit 14 is connected to the IO / VDD5V, INT SCP, and B0 / GND pin circuits of the main control unit 11, and converts the current signal of the sampling resistor into a voltage signal and inputs it to the main control unit 11.

[0036] The magnetic flux coupling and energy transfer circuit 13 includes a number of transformer coils. Each transformer coil leads out a head pin, a tail pin, and a middle pin. The middle pin is respectively connected to the positive electrode of each single cell in the lithium-ion battery pack through the first set and the second set of circuit interfaces. The head pin and the tail pin are respectively connected to the source and drain of the MOS transistor. The circuit between the MOS transistor and the first square wave and second square wave pins of the main control unit is connected to receive the square wave signal of the main control unit 11 to control the conduction or cut-off of the source and drain.

[0037] The main control unit 11 receives the voltage signal of the sampling circuit, compares the voltage signal with the set threshold value, and issues start equalization, stop equalization, and current limiting instructions to the magnetic flux coupling and energy transfer circuit 13 according to the comparison result.

[0038] In the scenario of using the equalization protection module 1 alone, that is, when only one set of equalization protection modules is used, as Figure 1 shown, it is a typical application schematic diagram of the equalization protection module proposed by the present invention. The first set and the second set of interfaces in the circuit interface of the equalization protection module 1 are sequentially connected to the two poles of each single cell in the lithium-ion battery pack 2. Each module can be used to equalize a lithium-ion battery pack 2 composed of up to 16 single cells; the third set of interfaces is connected to an external host computer 4. The specific connection method is as follows: there are a total of 17 interfaces in the first set and the second set of the circuit interface. The B0 interface is connected to the negative electrode of the lithium-ion battery pack 2 in series with a resistor. Each of the B1 to B16 interfaces is connected to the positive electrode of each single cell in the lithium-ion battery pack 2 in series with a resistor. The third set of interfaces GND1 and EN are connected to the external host computer 4 through connecting wires, which are used to transmit working parameter information and receive control instructions sent by the host computer 4. When necessary, leads can be connected from the positive and negative electrodes of each single cell in the lithium-ion battery pack 2 to the protection board 3, which is used to monitor and protect the charge and discharge current of the lithium-ion battery pack 2.

[0039] When there is a voltage difference between the single cells in the lithium-ion battery pack 2, the flux coupling and energy transfer circuit 13 of the equalization protection module 1 can automatically equalize the single cells with the voltage difference. The circuit of the flux coupling and energy transfer circuit 13 is as Figure 8 shown: It includes synchronous coils corresponding to each single cell. All synchronous coils share a magnetic core. Each group of synchronous coils leads out 3 connecting wires, namely the head end, the tail end, and the middle end. Among them, Bx-2 is the head end of each group of synchronous coils, connected to the positive electrode of the corresponding Bx battery; Bx-3 is the tail end of each group of synchronous coils, connected to the negative electrode of the corresponding Bx battery; Bx is connected to the instruction output terminal of the main control unit 11, receives the equalization instruction of the main control unit, and controls the opening and closing of each group of coil circuits to control the equalization of the corresponding single cell (x is a natural number with a value of 1 to 16).

[0040] When equalizing the lithium-ion battery pack 2, the equalization protection module 1 monitors the real-time temperature of the lithium-ion battery pack 2 through the temperature sampling circuit 16. The temperature sampling circuit is as Figure 4 shown, including an NTC resistor closely attached to the lithium-ion battery pack, a filter capacitor C64, and a pull-up resistor R86 connected to the VDD5V power supply. The NTC resistor is in parallel with the filter capacitor C64, one end is connected to the B0 interface of the equalization protection module 1, and the other end is connected to the SPI-1 / NTC pin of the main control unit 11 in the equalization protection module 1. The VDD5V pin of the main control unit 11 is connected to the SPI-1 / NTC pin of the main control unit 11 after being connected in series with the pull-up resistor R86. When the battery temperature is low, the NTC resistance value is large (such as extreme values like 50 kΩ or 100 kΩ, etc.), and the SPI-1 / NTC pin is at a high level; when the battery temperature rises, the NTC resistor's resistance value decreases after being heated. When the temperature rises to the threshold value, the SPI-1 / NTC pin is at a low level. The main control unit 11 judges whether the battery temperature is too high according to the high and low level signals, and opens and closes the equalization circuit to protect the lithium-ion battery pack 2.

[0041] During the equalization operation, the equalization protection module 1 simultaneously monitors the real-time equalization current of the lithium-ion battery pack 2 through the current sampling circuit 14. The current sampling circuit 14 is as Figure 5 shown. The overcurrent signal is converted into a voltage signal (pulse voltage) through coil electromagnetic induction. The pulse voltage will break down the zener diode D38, causing the NPN transistor of Q36 to turn on, and the PNP transistor of Q37 to achieve the holding and locking of the trigger level. At this time, the pulse peak trigger protection signal is fed back to the main control unit through the INT SCP pin, and the main control unit issues an instruction to interrupt the PWM signal to abort the equalization operation. When the equalization protection module 1 encounters an inrush current exceeding the threshold value, the overcurrent protection function is activated and the current loop is cut off to protect the module.

[0042] The single balancing protection module 1 described in the present invention can be used for a lithium-ion battery pack 2 composed of 16 or fewer single cells. When the number of single cells in the lithium-ion battery pack 2 that needs to be balanced is greater than 16, the balancing protection modules 1 can be cascaded. The specific cascading scheme is as Figure 2 shown: The second group of interfaces of each balancing protection module 1 are respectively connected to the B0 to B4 interfaces of the next-level balancing protection module 1; that is, B12 is connected to the B0 interface of the next-level module, B13 is connected to the B1 interface of the next-level module, B14 is connected to the B2 interface of the next-level module, B15 is connected to the B3 interface of the next-level module, and B16 is connected to the B4 interface of the next-level module. By analogy, when N balancing protection modules 1 are cascaded, up to 12N + 4 single cells can be balanced, so that when balancing and protecting a lithium-ion battery pack 2 composed of 16 or even more than 24 single cells, there is no need to specially design a balancing protection module, saving the usage cost.

[0043] When the parallel number of battery packs increases, that is, when the battery capacity increases, such as when the single battery pack capacity reaches 20 Ah or a larger capacity such as 200 Ah, the larger the battery capacity, the lower the balancing efficiency, and the balancing time required to balance the same battery voltage difference will be greatly increased; since the maximum balancing current of a single balancing protection module 1 has been determined, in order for the balancing module to handle the larger current brought by the larger battery capacity, it is necessary to redesign the balancing circuit parameters, increase the size of the balancing transformer, and select a high-current power MOS switch tube, etc. The balancing protection module 1 described in the present invention can be used in a large-current balancing scenario by connecting several balancing protection modules 1 in parallel through a wiring board 5 to form a balancing protection system. Based on the maximum balancing current of a single balancing protection module 1 being 3 A, if the number of balancing protection modules in the balancing protection system is N, a maximum balancing current of 3N A can be achieved. The specific scheme is as Figure 3 shown: The interfaces with the same number in the B0 to B16 interfaces of all balancing protection modules 1 are connected together and connected to the lithium-ion battery pack 2 through the wiring board 5. A connecting wire capable of withstanding 3N A current is required between the wiring board 5 and the lithium-ion battery pack 2.

[0044] The connection between the balancing protection module 1 and the wiring board 5 uses a pluggable connection terminal. On the premise of meeting the maximum balancing current, the insertion and removal of any one of the parallel-connected balancing protection modules 1 will not affect the working state of other balancing protection modules 1, allowing other balancing protection modules 1 to perform hot plugging and unplugging operations during the balancing process.

[0045] The balance protection module 1 described in the present invention can be connected to an external host computer 4 through a third set of interfaces, and this interface is connected to the registers inside the module. The user's host computer 4 can be connected to this interface through a lead wire, so as to realize operations such as starting balance, stopping balance, information exchange, transmitting instructions, etc., and transmit various data during the balance process, such as working status, fault conditions, etc., to the host computer in real time for display to the user.

[0046] The above are only the preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the inventive concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention.

Claims

1. A battery equalization protection module with multiple usage modes, characterized in that, It includes a circuit interface and an equalization protection circuit. There are 3 groups of the circuit interfaces (12) in total, which are arranged on the circuit board of the equalization protection circuit and connected to the equalization protection circuit. Among them, the first group of circuit interfaces has several interfaces for connecting to a lithium-ion battery pack (2); the second group of circuit interfaces has several interfaces for connecting to the next-level equalization protection module (1) in the cascaded usage scenario of the equalization protection module (1), or connecting to the lithium-ion battery pack (2) in the stand-alone usage scenario. The third group includes a ground interface and a communication interface, and the communication interface is used for communicating with an external host computer (4). The equalization protection circuit further includes: a main control unit (11), a communication circuit (17), a temperature sampling circuit (16), a voltage detection circuit (15), a current sampling circuit (14), and a flux coupling and energy transfer circuit (13); the main control unit (11) is respectively connected to each circuit and receives signals transmitted by each circuit; the communication circuit (17) is also connected to the third-group interface circuit of the circuit interface (12). The flux coupling and energy transfer circuit (13) includes several transformer coils, and each transformer coil leads out a head pin, a tail pin, and a middle pin. The middle pin is respectively connected to the positive electrode of each single-cell battery in the lithium-ion battery pack (2) through the first-group and second-group circuit interfaces. The head pin and the tail pin are respectively connected to the source and drain of an MOS transistor, and the MOS transistor is connected to the first square-wave and second square-wave pin circuits of the main control unit (11) to receive the square-wave signal of the main control unit (11) to control the conduction or cut-off of the source and drain. The main control unit (11) receives the voltage signal of the sampling circuit, compares the voltage signal with a set threshold value, and issues start equalization, stop equalization, and current limiting instructions to the flux coupling and energy transfer circuit (13) according to the comparison result.

2. The battery equalization protection module with multiple usage modes according to claim 1, characterized in that, In the case of only using one group of equalization protection modules (1), the first-group and second-group interfaces of the circuit interface (12) are sequentially connected to both poles of each single-cell battery in the lithium-ion battery pack, and a total of 17 interfaces can connect up to 16 single-cell batteries.

3. The battery equalization protection module with multiple usage modes according to claim 1, characterized in that, When at least two equalization protection modules are used for a lithium-ion battery pack (2) composed of more than 16 single-cell batteries, the second-group interfaces of each equalization protection module (1) are respectively connected to the first five interfaces of the first-group interfaces of the next-level equalization protection module (1); that is, B12 is connected to the B0 interface of the next-level module, B13 is connected to the B1 interface of the next-level module, B14 is connected to the B2 interface of the next-level module, B15 is connected to the B3 interface of the next-level module, and B16 is connected to the B4 interface of the next-level module.

4. A battery equalization protection module with multiple usage modes according to claim 1, characterized in that, In the parallel usage scenario of at least two groups of the equalization protection modules (1), the interfaces with the same number in the B0 to B16 interfaces of all equalization protection modules (1) are connected together and connected to the lithium-ion battery pack (2) through a wiring board (5).

5. A battery equalization protection module with multiple usage modes according to claim 1, characterized in that, The equalization protection module (1) is connected to the external host computer (4) through the third-group interface, and is used for receiving the control instructions of the host computer (4) and sending the parameter information of the battery pack.

6. A battery equalization protection module with multiple usage modes according to claim 1, characterized in that, There are a total of 17 interfaces in the first group and the second group of the circuit interface (12). The first interface in the first group of circuit interfaces is connected to the negative electrode of the lithium-ion battery pack (2) after being in series with a resistor, and each of the other interfaces is connected to the positive electrode of each single cell in the lithium-ion battery pack (2) after being in series with a resistor in sequence.

7. A battery equalization protection module with multiple usage modes according to claim 1, characterized in that, The temperature sampling circuit (16) performs temperature sampling through an NTC resistor that is in close contact with the lithium-ion battery pack, and is connected to the temperature sampling pin of the main control unit (11).

8. A battery equalization protection module with multiple usage modes according to claim 4, characterized in that, When the equalization protection modules are used in parallel, the current that the connection line between the wiring board (5) and the lithium-ion battery pack (2) can withstand should be greater than the sum of the currents that all equalization modules can withstand.

9. A battery equalization protection module with multiple usage modes according to claim 4, characterized in that, The connection between the equalization protection module (1) and the wiring board (5) is made by using a pluggable connection terminal.

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