High-safety lithium battery management system

Abstract

The utility model discloses a high-safety lithium battery management system which comprises a lithium battery pack, an anode input end, a cathode input end, an anode output end, a cathode output end, a charge-discharge control unit and a first short-circuit protection unit, the first short-circuit protection unit is used for detecting current between the negative input end and the negative output end and absorbing high voltage on the negative output end by adopting a capacitor during short circuit. The short-circuit protection unit is connected between the negative input end and the negative output end to detect the short-circuit current, and the capacitor is adopted to absorb the high voltage on the negative output end during short circuit, so that the absorption effect is better than the effect of a pure fast switching diode, and the pulse high voltage on the negative output end can be effectively absorbed; the potential safety hazard risk of the lithium battery management system is reduced, and good repeated impact resistance is achieved.

Description

Technical Field

[0001] The utility model relates to the technical field of lithium battery management, in particular to a high-safety lithium battery management system. Background Art

[0002] Existing lithium-ion battery packs typically use a battery protection board in a lithium-ion battery management system (BMS) managed by an intelligent MCU to provide overcharge, over-discharge, overcurrent, and short-circuit protection. The 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. The charge and discharge module includes a charge current limiting unit, a charging MOSFET circuit, a discharge MOSFET circuit, and a pre-discharge circuit. The presence of this protection circuit significantly improves battery safety and reliability.

[0003] In lithium-ion battery management systems (LBMs) ​​that control the negative-side MOSFET, the voltage at P- is significantly higher than the voltage at P+ during short-circuit protection. Conventional applications involve connecting a fast-switching diode in parallel between the positive (P+) and negative (P-) output terminals to absorb the high voltage at the negative output terminal (P-). However, due to the high current flowing through it, this high voltage cannot be fully absorbed, easily leading to MOSFET breakdown. Connecting a fast TVS diode in parallel between the negative output terminal (P-) and the negative input terminal (B-) to absorb the high voltage at the negative output terminal (P-) increases the risk of TVS breakdown, thus increasing the risk for the LBM. Utility Model Content

[0004] Existing lithium battery management systems cannot effectively absorb the high voltage on the negative output terminal during short-circuit protection, which poses a safety hazard to the lithium battery management system.

[0005] To address the above problems, a highly secure lithium battery management system is proposed. By connecting a short-circuit protection unit between the negative input terminal and the negative output terminal, the short-circuit current is detected, and a capacitor is used to absorb the high voltage on the negative output terminal during a short circuit. The absorption effect is better than that of a simple fast-switching diode, and it can effectively absorb the pulse high voltage on the negative output terminal, reducing the safety risk faced by the lithium battery management system and having good resistance to repeated impact.

[0006] A highly safe lithium battery management system, comprising:

[0007] Lithium battery pack;

[0008] Positive input terminal;

[0009] Negative input terminal;

[0010] Positive output terminal;

[0011] Negative output terminal;

[0012] Charge and discharge control unit;

[0013] a first short-circuit protection unit;

[0014] The positive terminal of the lithium battery pack is electrically connected to the positive input terminal and the positive output terminal respectively;

[0015] The negative terminal of the lithium battery pack is electrically connected to the negative electrode input terminal, the first terminal of the charge and discharge control unit, and the first terminal of the first short-circuit protection unit;

[0016] The second end of the charge and discharge control unit is electrically connected to the negative electrode output end and the second end of the first short-circuit protection unit;

[0017] The first short-circuit protection unit is used to detect the current between the negative input terminal and the negative output terminal, and to use a capacitor to absorb the high voltage on the negative output terminal in the event of a short circuit.

[0018] In conjunction with the high-safety lithium battery management system described in the present invention, in a first possible implementation manner, the first short-circuit protection unit includes:

[0019] Current detection circuit;

[0020] Amplification and comparison circuit;

[0021] Switching circuit;

[0022] Capacitor absorption circuit;

[0023] The negative electrode input terminal, the negative terminal of the lithium battery pack and the first terminal of the charge and discharge control unit are electrically connected to the first terminal of the current detection circuit;

[0024] The second end of the current detection circuit, the amplification and comparison circuit, the switch circuit, and the first end of the capacitor absorption circuit are electrically connected in sequence;

[0025] The second end of the capacitor absorption circuit is electrically connected to the negative electrode output end and the second end of the charge and discharge control unit.

[0026] In combination with the first possible implementation manner of the present utility model, in a second possible implementation manner, the charge and discharge control unit includes:

[0027] A first resistor, a first MOS transistor, a second MOS transistor and a control chip;

[0028] The first end of the first resistor is electrically connected to the negative output terminal of the lithium battery pack, and the second end is electrically connected to the source of the first MOS transistor;

[0029] The gate of the first MOS transistor is electrically connected to the discharge pin of the control chip, and the drain is electrically connected to the drain of the second MOS transistor;

[0030] The gate of the second MOS transistor is electrically connected to the charging pin of the control chip, and the source is electrically connected to the negative output terminal and the second end of the capacitor absorption circuit.

[0031] In combination with the second possible implementation manner of the present utility model, in a third possible implementation manner, the current detection circuit includes:

[0032] a second resistor and a third resistor;

[0033] A first end of the second resistor is electrically connected to the first end of the first resistor, and a second end of the second resistor is electrically connected to the amplification and comparison circuit;

[0034] The first end of the third resistor is electrically connected to the second end of the first resistor and the source of the first MOS transistor, and the second end of the third resistor is electrically connected to the amplification and comparison circuit.

[0035] In combination with the third possible implementation manner of the present utility model, in a fourth possible implementation manner, the switch circuit includes:

[0036] The third MOS tube;

[0037] The source of the third MOS tube is electrically connected to the negative terminal of the lithium battery pack, the gate is electrically connected to the amplification and comparison circuit, and the drain is electrically connected to the first end of the capacitor absorption circuit.

[0038] In combination with the fourth possible implementation manner of the present utility model, in a fifth possible implementation manner, the capacitive absorption circuit includes:

[0039] a first capacitor;

[0040] The first end of the first capacitor is electrically connected to the drain of the first MOS transistor, and the second end is electrically connected to the negative output end.

[0041] In combination with the fifth possible implementation of the present utility model, in a sixth possible implementation, the lithium battery management system further includes:

[0042] A second short-circuit protection unit;

[0043] The second short-circuit protection unit is connected between the positive output terminal and the negative output terminal.

[0044] In combination with the sixth possible implementation manner of the present utility model, in a seventh possible implementation manner, the second short-circuit protection unit includes:

[0045] a first diode;

[0046] The anode of the first diode is electrically connected to the negative output terminal, and the cathode of the first diode is electrically connected to the positive output terminal.

[0047] In combination with the seventh possible implementation of the present utility model, in an eighth possible implementation, the lithium battery management system further includes:

[0048] A third short-circuit protection unit;

[0049] The third short-circuit protection unit is connected between the positive terminal of the lithium battery pack and the positive output terminal.

[0050] In combination with the eighth possible implementation manner of the present utility model, in a ninth possible implementation manner, the third short-circuit protection unit includes:

[0051] First safety circuit;

[0052] The first safety circuit is connected between the positive input terminal and the positive output terminal of the lithium battery pack.

[0053] The high-safety lithium battery management system described in the utility model is implemented by connecting the short-circuit protection unit between the negative input terminal and the negative output terminal to detect the short-circuit current, and using a capacitor to absorb the high voltage on the negative output terminal during a short circuit. Its absorption effect is better than that of a simple fast-switching diode, and it can effectively absorb the pulse high voltage on the negative output terminal, reducing the safety risk faced by the lithium battery management system and having good resistance to repeated impact. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] 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.

[0055] Figure 1 This is a schematic diagram of module connections for a high-safety lithium battery management system in the present invention;

[0056] Figure 2 This is a schematic diagram of the circuit structure of a high-safety lithium battery management system in the present utility model. DETAILED DESCRIPTION

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] The existing lithium battery management system cannot effectively absorb the high voltage on the negative output terminal 140 (P-) during short circuit protection, which makes the lithium battery management system face safety risks.

[0063] In response to the above problems, a high-safety lithium battery management system is proposed. Figure 1 , Figure 1This is a schematic diagram of the module connection of a high-safety lithium battery management system in the present invention; a high-safety lithium battery management system, including a lithium battery pack 100, a positive input terminal 110 (B+), a negative input terminal 120 (B-), a positive output terminal 130 (P+), a negative output terminal 140 (P-), a charge and discharge control unit 200, and a first short-circuit protection unit 300; the positive terminal of the lithium battery pack 100 is electrically connected to the positive input terminal 110 (B+) and the positive output terminal 130 (P+); the lithium battery pack 100 The negative terminal of the charge-discharge control unit 200 is electrically connected to the negative input terminal 120 (B-), the first terminal of the charge-discharge control unit 200, and the first terminal of the first short-circuit protection unit 300; the second terminal of the charge-discharge control unit 200 is electrically connected to the negative output terminal 140 (P-) and the second terminal of the first short-circuit protection unit 300; the first short-circuit protection unit 300 is used to detect the current between the negative input terminal 120 (B-) and the negative output terminal 140 (P-), and use the capacitor C1 to absorb the high voltage on the negative output terminal 140 (P-) in the event of a short circuit.

[0064] The charge and discharge control unit 200 is connected in series between the negative input terminal 120 (B-) of the lithium battery pack 100 and the negative output terminal 140 (P-) of the system to manage the charging and discharging of the lithium battery pack 100. The first short-circuit protection unit 300 is connected in parallel with the charge and discharge control unit 200. During short-circuit protection, the voltage on the negative output terminal 140 (P-) is much higher than the voltage on the positive output terminal 130 (P+). The use of a diode alone cannot completely absorb the high voltage on the negative output terminal 140 (P-), resulting in the breakdown of the MOS tube Q of the charge and discharge control unit 200.

[0065] In this embodiment, the first short-circuit protection unit 300 uses capacitor C1 to absorb the high voltage at the negative output terminal 140 (P-), and absorbs the high voltage together with the diode connected between the positive output terminal 130 (P+) and the negative output terminal 140 (P-), thereby achieving a better effect. By connecting the short-circuit protection unit between the negative input terminal 120 (B-) and the negative output terminal 140 (P-), the short-circuit current is detected, and capacitor C1 is used to absorb the high voltage at the negative output terminal 140 (P-) during a short circuit. This absorption effect is better than that of a simple fast-switching diode, and can effectively absorb the pulsed high voltage at the negative output terminal 140 (P-), reducing the risk of safety hazards faced by the lithium battery management system and having good resistance to repeated impacts.

[0066] Furthermore, the first short-circuit protection unit 300 includes a current detection circuit, an amplification and comparison circuit, a switching circuit, and a capacitor C1 absorption circuit; the negative electrode input terminal 120 (B-), the negative terminal of the lithium battery pack 100, and the first end of the charge and discharge control unit are electrically connected to the first end of the current detection circuit; the second end of the current detection circuit, the amplification and comparison circuit, the switching circuit, and the first end of the capacitor C1 absorption circuit are electrically connected in sequence; the second end of the capacitor C1 absorption circuit is electrically connected to the negative electrode output terminal 140 (P-) and the second end of the charge and discharge control unit.

[0067] The current detection circuit is used to detect the circuit current on the full control unit circuit. When a short circuit occurs, the circuit current can reach several hundred amperes. The amplification and comparison circuit samples and amplifies the circuit current signal and compares it with the specified threshold value. The comparison result triggers the switch circuit to turn on the circuit, thereby using the capacitor C1 absorption circuit to absorb the high voltage.

[0068] Specifically, such as Figure 2 , Figure 2 This is a schematic diagram of the circuit structure of a high-safety lithium battery management system in the present invention. The charge and discharge control unit 200 includes a first resistor R2, a first MOS transistor Q1, a second MOS transistor Q2, and a control chip ATE. The first end of the first resistor R2 is electrically connected to the negative output terminal 140 (P-) of the lithium battery pack 100, and the second end is electrically connected to the source of the first MOS transistor Q1. The gate of the first MOS transistor Q1 is electrically connected to the discharge pin of the control chip ATE, and the drain is electrically connected to the drain of the second MOS transistor Q2. The gate of the second MOS transistor Q2 is electrically connected to the charge pin of the control chip ATE, and the source is electrically connected to the negative output terminal 140 (P-) and the second end of the absorption unit capacitor C1.

[0069] Specifically, such as Figure 2 The current detection circuit includes a second resistor R5 and a third resistor R4; a first end of the second resistor R5 is electrically connected to the first end of the first resistor R2, and a second end is electrically connected to the amplification and comparison circuit; a first end of the third resistor R4 is electrically connected to the second end of the first resistor R2 and the source of the first MOS transistor Q1, and a second end is electrically connected to the amplification and comparison circuit.

[0070] Specifically, such as Figure 2 The switch circuit includes a third MOS transistor Q3; the source of the third MOS transistor Q3 is electrically connected to the negative terminal of the lithium battery pack 100, the gate is electrically connected to the amplification and comparison circuit, and the drain is electrically connected to the first end of the capacitor C1 absorption circuit.

[0071] Specifically, such as Figure 2The capacitor C1 absorption circuit includes a first capacitor C1; a first end of the first capacitor C1 is electrically connected to the drain of the first MOS transistor Q1, and a second end is electrically connected to the negative output terminal 140 (P-).

[0072] Specifically, such as Figure 2 The lithium battery management system further includes: a second short-circuit protection unit 400; the second short-circuit protection unit 400 is connected between the positive output terminal 130 (P+) and the negative output terminal 140 (P-).

[0073] Specifically, such as Figure 2 The second short-circuit protection unit 400 includes a first diode U1 ; an anode of the first diode U1 is electrically connected to the negative output terminal 140 (P−), and a cathode of the first diode U1 is electrically connected to the positive output terminal 130 (P+).

[0074] Specifically, the lithium battery management system further includes a third short-circuit protection unit 500 connected between the positive input terminal and the positive output terminal 130 (P+) of the lithium battery pack 100. The third short-circuit protection unit 500 includes a first fuse F1 circuit connected between the positive terminal and the positive output terminal 130 (P+) of the lithium battery pack 100.

[0075] The short circuit protection principle in this embodiment is:

[0076] The capacitor C1 primarily utilizes the energy storage function to absorb the high voltage at the negative output terminal 140 (P-). The operating principle is as follows: When the positive output terminal 130 (P+) and the negative output terminal 140 (P-) are normally outputting, a short circuit occurs between the positive output terminal 130 (P+) and the negative output terminal 140 (P-). At this time, a current of several hundred amperes, or even several thousand amperes, will flow through the first resistor R2. The amplification and comparison circuit determines whether a short circuit has occurred and then controls the third MOS transistor Q3 to conduct. If a high voltage is generated at the negative output terminal 140 (P-), the voltage at the positive output terminal 130 (P+) and the negative output terminal 140 (P-) flows through the absorption capacitor C1 and the third MOS transistor Q3 to the negative input terminal 120 (B-). The amplification and comparison circuit turns on the third MOS transistor Q3 for a certain period of time and then turns it off to prepare for the next triggering.

[0077] A high-safety lithium battery management system implemented in the utility model detects the short-circuit current by connecting the short-circuit protection unit between the negative input terminal and the negative output terminal, and uses a capacitor to absorb the high voltage on the negative output terminal during a short circuit. Its absorption effect is better than that of a simple fast-switching diode, and it can effectively absorb the pulse high voltage on the negative output terminal, reducing the safety risk faced by the lithium battery management system and having good resistance to repeated impact.

[0078] 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 highly safe lithium battery management system, characterized by: include: Lithium battery pack; Positive input terminal; Negative input terminal; Positive output terminal; Negative output terminal; Charge and discharge control unit; a first short-circuit protection unit; The positive terminal of the lithium battery pack is electrically connected to the positive input terminal and the positive output terminal respectively; The negative terminal of the lithium battery pack is electrically connected to the negative electrode input terminal, the first terminal of the charge and discharge control unit, and the first terminal of the first short-circuit protection unit; The second end of the charge and discharge control unit is electrically connected to the negative electrode output end and the second end of the first short-circuit protection unit; The first short-circuit protection unit is used to detect the current between the negative input terminal and the negative output terminal, and to use a capacitor to absorb the high voltage on the negative output terminal in the event of a short circuit.

2. The high-safety lithium battery management system according to claim 1, characterized in that: The first short-circuit protection unit includes: Current detection circuit; Amplification and comparison circuit; Switching circuit; Capacitor absorption circuit; The negative electrode input terminal, the negative terminal of the lithium battery pack and the first terminal of the charge and discharge control unit are electrically connected to the first terminal of the current detection circuit; The second end of the current detection circuit, the amplification and comparison circuit, the switch circuit, and the first end of the capacitor absorption circuit are electrically connected in sequence; The second end of the capacitor absorption circuit is electrically connected to the negative electrode output end and the second end of the charge and discharge control unit.

3. The high-safety lithium battery management system according to claim 2, characterized in that: The charge and discharge control unit includes: A first resistor, a first MOS transistor, a second MOS transistor and a control chip; The first end of the first resistor is electrically connected to the negative output terminal of the lithium battery pack, and the second end is electrically connected to the source of the first MOS transistor; The gate of the first MOS transistor is electrically connected to the discharge pin of the control chip, and the drain is electrically connected to the drain of the second MOS transistor; The gate of the second MOS transistor is electrically connected to the charging pin of the control chip, and the source is electrically connected to the negative output terminal and the second end of the capacitor absorption circuit.

4. The high-safety lithium battery management system according to claim 3, characterized in that: The current detection circuit includes: a second resistor and a third resistor; A first end of the second resistor is electrically connected to the first end of the first resistor, and a second end of the second resistor is electrically connected to the amplification and comparison circuit; The first end of the third resistor is electrically connected to the second end of the first resistor and the source of the first MOS transistor, and the second end of the third resistor is electrically connected to the amplification and comparison circuit.

5. The high-safety lithium battery management system according to claim 4, characterized in that: The switching circuit comprises: The third MOS tube; The source of the third MOS tube is electrically connected to the negative terminal of the lithium battery pack, the gate is electrically connected to the amplification and comparison circuit, and the drain is electrically connected to the first end of the capacitor absorption circuit.

6. The high-safety lithium battery management system according to claim 5, characterized in that: The capacitive absorption circuit includes: a first capacitor; The first end of the first capacitor is electrically connected to the drain of the first MOS transistor, and the second end is electrically connected to the negative output end.

7. The high-safety lithium battery management system according to claim 6, characterized in that: The lithium battery management system further includes: a second short-circuit protection unit; The second short-circuit protection unit is connected between the positive output terminal and the negative output terminal.

8. The high-safety lithium battery management system according to claim 7, characterized in that: The second short-circuit protection unit includes: a first diode; The anode of the first diode is electrically connected to the negative output terminal, and the cathode of the first diode is electrically connected to the positive output terminal.

9. The high-safety lithium battery management system according to any one of claims 1 to 8, characterized in that: The lithium battery management system further includes: A third short-circuit protection unit; The third short-circuit protection unit is connected between the positive terminal of the lithium battery pack and the positive output terminal.

10. The high-safety lithium battery management system according to claim 9, characterized in that: The third short-circuit protection unit includes: First safety circuit; The first safety circuit is connected between the positive input terminal and the positive output terminal of the lithium battery pack.

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