Lithium battery protection circuit

Abstract

The utility model discloses a lithium battery protection circuit, which comprises a primary protection module, a first secondary protection module, a second secondary protection module and a switch module, the input end of the primary protection module is electrically connected with each cascaded battery in the lithium battery pack; the output end of the primary protection module is electrically connected with the input end of the switch module and the first secondary protection module. The first end and the third end of the second secondary protection module are electrically connected with the positive electrode end and the positive electrode output end of the lithium battery pack respectively; the second end of the second secondary protection module is electrically connected with the output end of the switch module; and the first secondary protection module is used for performing secondary temperature protection according to the environment temperature of the lithium battery pack. The primary protection module, the first secondary protection module and the second secondary protection module are arranged in the lithium battery pack circuit to perform overvoltage and over-temperature protection on the lithium battery circuit respectively, so that the risk of thermal runaway of the circuit is reduced, and the over-temperature protection effect can still be achieved under the condition that the primary protection module is out of control.

Description

Technical Field

[0001] The utility model relates to the technical field of lithium battery protection, in particular to a lithium battery protection circuit. Background Art

[0002] Typically, a smart power management lithium battery protection board design consists of a power management chip and a protection chip (or an integrated chip of both), field-effect transistors (FETs), peripheral resistors and capacitors, and fuses to provide overcharge, over-discharge, overcurrent, and short-circuit protection. A lithium battery management system (BMS) battery protection board includes an MCU, an analog front-end module, a charge and discharge module, a wake-up switch, a battery terminal for connecting to the battery pack, a charger terminal for connecting to a charger, and a load terminal for connecting to a load.

[0003] Protection chips are generally used as primary protection, and fuses are used as secondary protection, such as over-temperature protection, over-current protection, and short-circuit protection. The secondary protection method uses overvoltage in the battery cell to trigger the melting of the three-terminal fuse. The protection function is relatively simple, and the effect of the secondary protection is poor. Utility Model Content

[0004] The secondary protection function of existing lithium battery management is single and cannot achieve the secondary protection effect actually required.

[0005] To address the above problems, a lithium battery protection circuit is proposed. By setting a primary protection module, a first-level protection module, and a second-level protection module in the lithium battery pack circuit, the lithium battery circuit is protected from overvoltage and overtemperature respectively, reducing the risk of thermal runaway of the circuit. Even if the primary protection module is out of control, the overtemperature protection function can still be achieved.

[0006] A lithium battery protection circuit, comprising:

[0007] First level protection module;

[0008] First and second level protection modules;

[0009] Second level protection module;

[0010] Switch module;

[0011] The input end of the primary protection module is electrically connected to each cascaded battery in the lithium battery pack;

[0012] The output end of the first-level protection module is electrically connected to the input end of the switch module and the first-level protection module respectively;

[0013] The first end and the third end of the second secondary protection module are electrically connected to the positive terminal and the positive output terminal of the lithium battery pack respectively;

[0014] The second end of the second secondary protection module is electrically connected to the output end of the switch module;

[0015] The first and second level protection modules are used to perform second level temperature protection according to the ambient temperature of the lithium battery pack.

[0016] In conjunction with the lithium battery protection circuit of the present invention, in a first possible implementation manner, the primary protection module includes:

[0017] Protect the chip;

[0018] a first output unit;

[0019] The detection pin of the protection chip is electrically connected to each battery of the lithium battery pack, and the output pin of the protection chip is electrically connected to the first output unit.

[0020] In combination with the first possible implementation manner of the present utility model, in a second possible implementation manner, the protection chip further includes a control pin;

[0021] The control pin is electrically connected to the positive terminal of the lithium battery pack.

[0022] In combination with the first possible implementation manner of the present utility model, in a second possible implementation manner, the first output unit includes:

[0023] Output resistance;

[0024] a first diode;

[0025] A first end of the output resistor is electrically connected to an output pin of the protection chip, and a second end of the output resistor is electrically connected to an anode of the first diode.

[0026] In combination with the second possible implementation manner of the present invention, in a third possible implementation manner, the first secondary protection module includes:

[0027] Temperature detection unit;

[0028] Comparison unit;

[0029] a second output unit;

[0030] The temperature detection unit, the comparison unit, and the second output unit are electrically connected in sequence;

[0031] The temperature detection unit is used to detect the ambient temperature and convert it into an electrical signal;

[0032] The comparison unit is used to compare the electrical signal with a specified threshold value, and output a high-level signal when the electrical signal exceeds the specified threshold value;

[0033] The second output unit is used to output the high-level signal to the switch module to trigger conduction.

[0034] In combination with the third possible implementation manner of the present invention, in a fourth possible implementation manner, the temperature detection unit includes a first temperature sensor.

[0035] In combination with the fourth possible implementation manner of the present utility model, in a fifth possible implementation manner, the comparison unit includes a first comparator;

[0036] A first end of the first temperature sensor is electrically connected to a power supply, and a second end of the first temperature sensor is electrically connected to a positive terminal of the first comparator.

[0037] In combination with the fifth possible implementation manner of the present utility model, in a sixth possible implementation manner, the second output unit includes a second diode;

[0038] An anode of the second diode is electrically connected to the output end of the first comparator, and a cathode of the second diode is electrically connected to the cathode of the first diode and the switch module.

[0039] In combination with the sixth possible implementation manner of the present utility model, in a seventh possible implementation manner, the switch module includes:

[0040] First MOS tube;

[0041] The gate of the first MOS transistor is electrically connected to the cathode of the first diode and the cathode of the second diode, the source of the first MOS transistor is grounded, and the drain of the first MOS transistor is electrically connected to the second secondary protection module.

[0042] In combination with the seventh possible implementation manner of the present utility model, in an eighth possible implementation manner, the second secondary protection module includes:

[0043] Fuse circuit;

[0044] The insurance circuit is electrically connected to the positive terminal of the lithium battery pack, the drain and the positive output terminal of the first MOS tube respectively.

[0045] The lithium battery protection circuit described in the present invention is implemented by setting a primary protection module, a first-level secondary protection module, and a second-level secondary protection module in the lithium battery pack circuit to respectively protect the lithium battery circuit from overvoltage and overtemperature, thereby reducing the risk of thermal runaway of the circuit. Even if the primary protection module is out of control, the overtemperature protection function can still be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0047] Figure 1 This is a schematic diagram of module connections for a lithium battery protection circuit in the present invention;

[0048] Figure 2 The figure is a schematic diagram of the circuit structure of a lithium battery protection circuit in the present invention. DETAILED DESCRIPTION

[0049] The following is a clear and complete description of the technical solutions of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, other embodiments obtained by ordinary technicians in this field without creative work are all within the scope of protection of the present invention.

[0050] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used herein in the specification of this invention are intended only to describe specific embodiments and are not intended to limit the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0051] It should be noted that when an element is referred to as being “fixed on” or “disposed on” another element, it may be directly on the other element or indirectly on the other element. When an element is referred to as being “connected to” another element, it may be directly connected to the other element or indirectly connected to the other element.

[0052] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0053] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. Throughout the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0054] The secondary protection function of existing lithium battery management is single and cannot achieve the secondary protection effect actually required.

[0055] In view of the above problems, a lithium battery protection circuit is proposed.

[0056] A lithium battery protection circuit, such as Figure 1 , Figure 1 This is a module connection diagram of a lithium battery protection circuit in the present invention; it includes a primary protection module 200, a first and second protection modules 300, a second and second protection module 500, and a switch module 400; the input end of the primary protection module 200 is electrically connected to each cascaded battery in the lithium battery pack 100; the output end of the primary protection module 200 is electrically connected to the input end of the switch module 400 and the first and second protection modules 300, respectively; the first end and the third end of the second and second protection module 500 are electrically connected to the positive terminal 110 (B+) and the positive output terminal 120 (P+) of the lithium battery pack 100, respectively; the second end of the second and second protection modules 500 is electrically connected to the output end of the switch module 400; the first and second protection modules 300 are used to perform secondary temperature protection according to the ambient temperature of the lithium battery pack 100.

[0057] When overvoltage occurs, the primary protection module 200 outputs a high-level signal to the switch module 400, triggering the switch module 400 to connect to the second secondary protection module 500, thereby causing the fuse circuit in the second secondary protection module 500 to fuse, thereby protecting the circuit.

[0058] In this embodiment, when the ambient temperature of the lithium battery pack 100 is too high, the first and second protection modules 300 operate and output a high-level signal to the switch module 400, triggering the switch module 400 to conduct and connect to the second and second protection module 500, causing the fuse circuit in the second and second protection module 500 to fuse, thereby also protecting the circuit. In other words, even if the first protection module 200 is not operating, the first and second protection modules 300 can still provide overtemperature protection. By providing the first protection module 200, the first and second protection modules 300, and the second and second protection modules 500 in the lithium battery pack 100 circuit, the lithium battery circuit is protected from overvoltage and overtemperature respectively, reducing the risk of thermal runaway of the circuit. Even in the event of a runaway of the first protection module 200, the temperature overtemperature protection function can still be provided.

[0059] Furthermore, if Figure 2 , Figure 2 This is a schematic diagram of the circuit structure of a lithium battery protection circuit in the present invention. The primary protection module 200 includes a protection chip U1 and a first output unit. The detection pins (VC2-VC5) of the protection chip U1 are electrically connected to each battery cell of the lithium battery pack 100, and the output pin OUT of the protection chip U1 is electrically connected to the first output unit.

[0060] Furthermore, if Figure 2 The protection chip U1 further includes a control pin CTL; the control pin CTL is electrically connected to the positive terminal 110 (B+) of the lithium battery pack 100.

[0061] Furthermore, if Figure 2 The first output unit includes an output resistor R4 and a first diode D1; a first end of the output resistor R4 is electrically connected to the output pin OUT of the protection chip U1, and a second end thereof is electrically connected to the anode of the first diode D1.

[0062] The circuit structure of the first level protection module 200 is as follows: Figure 2 The protection chip includes detection pins (VC2-VC5), which are electrically connected to the corresponding battery through capacitors (C1, C2, C3, C4) and resistors (R2, R3, R4, R5) for detection. The control pin CTL is electrically connected to the positive terminal 110 (B+) of the battery pack through capacitor C4 and resistor R1. The output pin is OUT.

[0063] Furthermore, if Figure 2 The first and second level protection modules 300 include a temperature detection unit, a comparison unit, and a second output unit; the temperature detection unit, the comparison unit, and the second output unit are electrically connected in sequence; the temperature detection unit is used to detect the ambient temperature and convert it into an electrical signal; the comparison unit is used to compare the electrical signal with a specified threshold, and output a high-level signal when the specified threshold is exceeded; the second output unit is used to output the high-level signal to the switch module 400 to trigger conduction.

[0064] Furthermore, if Figure 2 , the temperature detection unit includes a first temperature sensor R11.

[0065] Furthermore, if Figure 2 The comparison unit includes a first comparator U3; a first end of the first temperature sensor R11 is electrically connected to the power supply, and a second end is electrically connected to the positive terminal 110 (B+) of the first comparator U3.

[0066] Furthermore, if Figure 2The second output unit includes a second diode D2; the anode of the second diode D2 is electrically connected to the output end of the first comparator U3, and the cathode is electrically connected to the cathode of the first diode D1 and the switch module 400.

[0067] Furthermore, if Figure 2 The switch module 400 includes a first MOS transistor Q1; the gate of the first MOS transistor Q1 is electrically connected to the cathode of the first diode D1 and the cathode of the second diode D2, the source of the first MOS transistor Q1 is grounded, and the drain of the first MOS transistor Q1 is electrically connected to the second secondary protection module 500.

[0068] Furthermore, if Figure 2 The second secondary protection module 500 includes a fuse circuit F1 ; the fuse circuit F1 is electrically connected to the positive terminal 110 (B+) of the lithium battery pack 100 , the drain of the first MOS transistor Q1 , and the positive output terminal 120 (P+).

[0069] The lithium battery protection circuit of the present invention is implemented by setting a primary protection module 200, a first-level secondary protection module 300, and a second-level secondary protection module 500 in the lithium battery pack 100 circuit to respectively protect the lithium battery circuit from overvoltage and overtemperature, thereby reducing the risk of thermal runaway of the circuit. Even if the primary protection module 200 is out of control, the overtemperature protection function can still be achieved.

[0070] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A lithium battery protection circuit, characterized in that: include: First level protection module; First and second level protection modules; Second level protection module; Switch module; The input end of the primary protection module is electrically connected to each cascaded battery in the lithium battery pack; The output end of the first-level protection module is electrically connected to the input end of the switch module and the first-level protection module respectively; The first end and the third end of the second secondary protection module are electrically connected to the positive terminal and the positive output terminal of the lithium battery pack respectively; The second end of the second secondary protection module is electrically connected to the output end of the switch module; The first and second level protection modules are used to perform second level temperature protection according to the ambient temperature of the lithium battery pack.

2. The lithium battery protection circuit according to claim 1, characterized in that: The first-level protection module includes: Protect the chip; a first output unit; The detection pin of the protection chip is electrically connected to each battery of the lithium battery pack, and the output pin of the protection chip is electrically connected to the first output unit.

3. The lithium battery protection circuit according to claim 2, characterized in that: The protection chip includes a control pin; The control pin is electrically connected to the positive terminal of the lithium battery pack.

4. The lithium battery protection circuit according to claim 3, characterized in that: The first output unit includes: Output resistance; a first diode; A first end of the output resistor is electrically connected to an output pin of the protection chip, and a second end of the output resistor is electrically connected to an anode of the first diode.

5. The lithium battery protection circuit according to claim 4, characterized in that: The first and second level protection modules include: Temperature detection unit; Comparison unit; a second output unit; The temperature detection unit, the comparison unit, and the second output unit are electrically connected in sequence; The temperature detection unit is used to detect the ambient temperature and convert it into an electrical signal; The comparison unit is used to compare the electrical signal with a specified threshold value, and output a high-level signal when the electrical signal exceeds the specified threshold value; The second output unit is used to output the high-level signal to the switch module to trigger conduction.

6. The lithium battery protection circuit according to claim 5, characterized in that: The temperature detection unit includes a first temperature sensor.

7. The lithium battery protection circuit according to claim 6, characterized in that: The comparison unit includes a first comparator; A first end of the first temperature sensor is electrically connected to a power supply, and a second end of the first temperature sensor is electrically connected to a positive terminal of the first comparator.

8. The lithium battery protection circuit according to claim 7, characterized in that: The second output unit includes a second diode; An anode of the second diode is electrically connected to the output end of the first comparator, and a cathode of the second diode is electrically connected to the cathode of the first diode and the switch module.

9. The lithium battery protection circuit according to claim 8, characterized in that: The switch module includes: First MOS tube; The gate of the first MOS transistor is electrically connected to the cathode of the first diode and the cathode of the second diode, the source of the first MOS transistor is grounded, and the drain of the first MOS transistor is electrically connected to the second secondary protection module.

10. The lithium battery protection circuit according to any one of claims 1 to 9, characterized in that: The second level protection module includes: Fuse circuit; The insurance circuit is electrically connected to the positive terminal of the lithium battery pack, the drain of the first MOS tube and the positive output terminal respectively.

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