Circuit for realizing protection of multiple series lithium batteries by cascade detection logic control

Abstract

This utility model belongs to the field of lithium battery technology, specifically relating to a circuit for cascaded detection logic control to protect multiple lithium battery strings. By cascading multiple single-cell lithium battery protection ICs and combining them with a logic control circuit constructed using PNP transistors, the circuit can precisely control the conduction or cutoff of the charging / discharging MOSFETs based on the output signal of each single-cell lithium battery protection IC, thereby achieving efficient protection for multiple lithium battery strings. The simple cascading method adapts to lithium battery packs with different numbers of strings, eliminating the need for complex protection circuits for each string, greatly reducing hardware costs and system complexity. The number of cascaded single-cell lithium battery protection ICs can be flexibly adjusted according to actual needs, making it suitable for battery pack applications in consumer electronics and power tools where cost control is crucial. Therefore, it not only solves the problems of high cost and complex design in existing technologies but also improves the stability and reliability of the system.

Description

Technical Field

[0001] This utility model belongs to the field of lithium battery technology, specifically relating to a circuit for cascaded detection logic control to protect multiple lithium batteries. Background Technology

[0002] Rechargeable lithium-ion battery packs, as core components of energy storage, are widely used in consumer digital products, power tools, drones, electric vehicles, as well as backup power supplies and home energy storage. With the increasing market demand for these devices, cost control has become paramount in the development, design, and manufacturing of consumer electronics products. Price advantages can help newly developed products better capture the market. Existing lithium battery protection circuit solutions typically use independent single-cell lithium battery protection ICs to monitor the status of each cell (such as overcharge, over-discharge, and overcurrent during charging and discharging) and take corresponding protective measures. However, this traditional method requires a separate protection circuit for each cell when dealing with multiple lithium battery strings, increasing the complexity and cost of the overall system.

[0003] The main problem with existing technologies is that in the application of multi-cell lithium battery packs, in order to achieve comprehensive protection functions (including overcharge protection, over-discharge protection and overcurrent protection), additional protection circuits and control chips are often required. This not only increases hardware costs, but also increases the design complexity and maintenance difficulty of the system. Utility Model Content

[0004] The purpose of this invention is to provide a circuit for cascaded detection logic control to protect multiple lithium batteries, thereby solving the problems mentioned in the background art.

[0005] To achieve the above objectives, this utility model adopts the following technical solution: a circuit for cascaded detection logic control to protect multiple lithium batteries, comprising:

[0006] Multiple single-cell lithium battery protection ICs are used to collect the voltage and current signals of the corresponding cells respectively;

[0007] A logic control circuit, cascaded with the single-cell lithium battery protection IC, is used to control the conduction or cutoff of the charging and discharging MOS transistor according to the output signal of the single-cell lithium battery protection IC;

[0008] Charge and discharge MOSFETs are used to implement overcharge protection, over-discharge protection, and overcurrent protection for multi-cell lithium batteries under the control of logic control circuits.

[0009] The single-cell lithium battery protection ICs are connected in a cascaded manner, and the logic control circuit is implemented through PNP transistors. The number of cascaded single-cell lithium battery protection ICs can be adjusted to adapt to lithium battery packs with different numbers of cells in series.

[0010] Preferably, the number of individual lithium battery protection ICs is consistent with the number of cells in the lithium battery pack, and each individual lithium battery protection IC collects voltage and current information for one cell in a string.

[0011] Preferably, the logic control circuit includes a voltage divider resistor network for providing a drive voltage to the PNP transistor to control the conduction state of the charging and discharging MOSFET; the voltage of the voltage divider resistor network is 15V.

[0012] Preferably, the overcharge protection includes: when any single-cell lithium battery protection IC detects that the corresponding cell voltage is overcharged, its OC pin outputs a low level, triggering the PNP transistor to conduct, thereby pulling down the driving voltage of the charging MOSFET and disconnecting the charging circuit.

[0013] Preferably, the over-discharge protection includes: when any single-cell lithium battery protection IC detects that the corresponding cell voltage is undervoltage, its OD pin outputs a low level, triggering the PNP transistor to conduct, thereby pulling down the drive voltage of the discharge MOSFET and disconnecting the discharge circuit.

[0014] Preferably, the overcurrent protection includes: when the voltage drop across the current sensing resistor exceeds a preset threshold, the corresponding single-cell lithium battery protection IC outputs a low-level signal to trigger the logic control circuit to cut off the charging and discharging circuit.

[0015] Preferably, the single-cell lithium battery protection IC is an integrated circuit of model DW01, and the PNP transistor in the logic control circuit is a general-purpose transistor.

[0016] The technical effects and advantages of this utility model are as follows: Compared with the prior art, the cascaded detection logic control circuit proposed in this utility model for protecting multiple lithium batteries has the following advantages:

[0017] This invention utilizes a cascaded connection of multiple single-cell lithium battery protection ICs, combined with a logic control circuit constructed using PNP transistors. This allows for precise control of the charging / discharging MOSFETs based on the output signal of each individual lithium battery protection IC, achieving efficient protection for multiple lithium battery cells. The simple cascading method adapts to lithium battery packs with varying numbers of cells, eliminating the need for complex protection circuits for each cell, significantly reducing hardware costs and system complexity. The number of cascaded single-cell lithium battery protection ICs can be flexibly adjusted according to actual needs, making it suitable for battery pack applications in consumer electronics and power tools where cost control is crucial. Therefore, it not only solves the problems of high cost and complex design in existing technologies but also improves system stability and reliability. Attached Figure Description

[0018] Figure 1 This is the circuit diagram of this utility model. Detailed Implementation

[0019] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. The specific embodiments described herein are only used to explain the present utility model and are not intended to limit the present utility model. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0020] This utility model provides a method such as Figure 1 The cascaded detection logic control circuit shown is used to implement protection for multiple lithium batteries. The circuit includes:

[0021] - Multiple individual lithium battery protection ICs collect the voltage and current signals of the corresponding cells respectively; the number of individual lithium battery protection ICs is consistent with the number of series in the lithium battery pack, and each individual lithium battery protection IC collects the voltage and current information of a series of cells.

[0022] - A logic control circuit, cascaded with the single-cell lithium battery protection IC, controls the conduction or cutoff of the charging and discharging MOS transistor according to the output signal of the single-cell lithium battery protection IC;

[0023] - The charging / discharging MOSFET, under the control of the logic control circuit, provides overcharge protection, over-discharge protection, and overcurrent protection for multi-cell lithium batteries. The logic control circuit includes a voltage divider resistor network to provide a drive voltage to the PNP transistors, thereby controlling the conduction state of the charging / discharging MOSFET. The voltage of the voltage divider resistor network is 15V.

[0024] The overcharge protection mechanism is as follows: When any single-cell lithium battery protection IC detects that the corresponding cell voltage exceeds the preset charging threshold, its OC pin will output a low-level signal, which will trigger the PNP transistor to conduct, causing the driving voltage of the charging MOSFET to decrease, and finally disconnecting the charging circuit.

[0025] The over-discharge protection mechanism is as follows: When any single-cell lithium battery protection IC detects that the corresponding cell voltage is lower than the preset discharge threshold, its OD pin will output a low-level signal, triggering the PNP transistor to conduct, thereby reducing the drive voltage of the discharge MOSFET and disconnecting the discharge circuit.

[0026] The overcurrent protection mechanism is as follows: when the voltage drop across the current sensing resistor exceeds the preset threshold, the corresponding single-cell lithium battery protection IC will output a low-level signal, triggering the logic control circuit to cut off the charging and discharging circuit.

[0027] The individual lithium battery protection ICs are connected in a cascaded manner, while the logic control circuit uses PNP transistors for precise logic control. By flexibly adjusting the number of cascaded individual lithium battery protection ICs, it can adapt to lithium battery packs with different numbers of cells in series. Furthermore, the individual lithium battery protection ICs use the DW01 integrated circuit, while the PNP transistors in the logic control circuit are general-purpose transistors.

[0028] The working principle is as follows:

[0029] This example uses four DWO1 single-cell lithium battery protection ICs (e.g., Fuchuang), cascaded together with a logic control circuit built using PNP transistors, to achieve a full-function protection circuit for four rechargeable lithium batteries. This circuit offers stable performance, excellent price, and the number of cascaded cells can be adjusted according to the actual number of working cells, making it suitable for battery pack applications in consumer electronics and power tools where cost control is a primary concern.

[0030] B- is the negative terminal of the four-cell battery pack; B1 is the positive terminal of the lowest-numbered cell in the pack; U1 is responsible for collecting the voltage signal of the lowest-numbered cell B1, and also for collecting the operating current of the entire pack; other ICs collect the voltage information of the other cells.

[0031] When the example is operating normally, the OD pin of U1 outputs a high level, transistor Q4 is in the off state, the DSG- signal is low, and transistor Q11 is also in the off state. At this time, the voltage of B4 is divided by resistors R22 and R23, generating a driving voltage of approximately 15V to drive the discharge MOSFET Q1, turning on Q1 and allowing the PACK battery pack to discharge normally. Similarly, during normal operation, the OC pin of U1 outputs a high level, transistor Q3 is in the off state, the CHG- signal is low, and transistor Q13 is also in the off state. The voltage of B4 is divided by resistors R29 and R32, generating a driving voltage of approximately 15V to drive the charging MOSFET Q2, turning on Q2 and allowing the PACK battery pack to charge normally.

[0032] Overcharge protection: When the U1 protection IC detects overcharge in cell B1, the OC pin of U1 outputs a low level, transistor Q3 turns on, the CHG- signal goes high, transistor Q13 also turns on, the driving voltage of charging MOSFET Q2 is pulled low by Q13, Q2 turns off, and the PACK battery pack disconnects the charging circuit, thus achieving overcharge protection. Similarly, other corresponding series can also achieve Q2 turning off, disconnecting the PACK battery pack charging circuit, thus achieving overcharge protection.

[0033] Over-discharge protection: When the U1 protection IC detects undervoltage in cell B1, the OD pin of U1 outputs a low level, transistor Q4 turns on, the DSG- signal goes high, and transistor Q11 also turns on. The drive voltage of the discharge MOSFET Q1 is pulled low by Q11, Q1 turns off, and the PACK battery pack disconnects the discharge circuit, achieving over-discharge protection. Similarly, other corresponding series can also achieve Q1 turning off, disconnecting the PACK battery pack discharge circuit, and achieving over-discharge protection.

[0034] Overcurrent protection: When current flows through the PACK battery pack circuit, a corresponding voltage drop will be generated across the current sensing resistor RS1. When the U1 protection IC detects that this voltage drop exceeds the charging or discharging protection threshold, it will change the output level of the OC or OD pin accordingly, cutting off the corresponding charging or discharging MOS, thus disconnecting the charging and discharging circuit of the PACK battery pack, thereby realizing the overcurrent protection function.

[0035] Finally, it should be noted that the above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A circuit for cascaded detection logic control to protect multiple lithium batteries, characterized in that, include: Multiple single-cell lithium battery protection ICs are used to collect the voltage and current signals of the corresponding cells respectively; A logic control circuit, cascaded with the single-cell lithium battery protection IC, is used to control the conduction or cutoff of the charging and discharging MOS transistor according to the output signal of the single-cell lithium battery protection IC; Charge and discharge MOSFETs are used to implement overcharge protection, over-discharge protection, and overcurrent protection for multi-cell lithium batteries under the control of logic control circuits. The single-cell lithium battery protection ICs are connected in a cascaded manner, and the logic control circuit is implemented through PNP transistors. The number of cascaded single-cell lithium battery protection ICs can be adjusted to adapt to lithium battery packs with different numbers of cells in series.

2. The circuit for cascaded detection logic control to protect multiple lithium batteries according to claim 1, characterized in that, The number of individual lithium battery protection ICs is the same as the number of cells in the lithium battery pack, and each individual lithium battery protection IC collects the voltage and current information of one cell in the pack.

3. The circuit for cascaded detection logic control to protect multiple lithium batteries according to claim 1, characterized in that, The logic control circuit includes a voltage divider resistor network for providing a drive voltage to the PNP transistor to control the conduction state of the charging and discharging MOSFET.

4. The circuit for cascaded detection logic control to protect multiple lithium batteries according to claim 3, characterized in that, The voltage of the voltage divider resistor network is 15V.

5. The circuit for cascaded detection logic control to protect multiple lithium batteries according to claim 1, characterized in that, Overcharge protection includes: when any single-cell lithium battery protection IC detects that the corresponding cell voltage is overcharged, its OC pin outputs a low level, triggering the PNP transistor to conduct, thereby pulling down the driving voltage of the charging MOSFET and disconnecting the charging circuit.

6. The circuit for cascaded detection logic control to protect multiple lithium batteries according to claim 1, characterized in that, Over-discharge protection includes: when any single-cell lithium battery protection IC detects that the corresponding cell voltage is undervoltage, its OD pin outputs a low level, triggering the PNP transistor to conduct, thereby pulling down the drive voltage of the discharge MOSFET and disconnecting the discharge circuit.

7. The circuit for cascaded detection logic control to protect multiple lithium batteries according to claim 1, characterized in that, Overcurrent protection includes: when the voltage drop across the current sensing resistor exceeds a preset threshold, the corresponding single-cell lithium battery protection IC outputs a low-level signal, triggering the logic control circuit to cut off the charging and discharging circuit.

8. The circuit for cascaded detection logic control to protect multiple lithium batteries according to claim 1, characterized in that, The single-cell lithium battery protection IC is an integrated circuit of model DW01, and the PNP transistor in the logic control circuit is a general-purpose transistor.

Images