A battery protection circuit with double protection function
Patent Information
- Application Number
- CN202522336334.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-04
- Publication Date
- 2026-10-09
- Estimated Expiration
- 2035-11-04
AI Technical Summary
[0002]在电池领域，电池保护板通常为一重检测电路和一重保护电路进行管控，当电池保护板的元器件失效时，电池的单重的保护电路无法对电池进行有效监测和保护，导致电池无法正常进行安全使用，可靠性较低
本实用新型两套独立的第一保护电路和第二保护电路，检测输入电压，电流和温度信号可以实现对于输入电压过高或者过低的判断，避免电池供电系统在元器件损坏的时候出现不当使用的情况，从根本上杜绝了单点故障导致整个保护系统失效的风险，从而让电池充放电更安全；采用专用硬件IC和纯硬件驱动逻辑，保护响应速度远快于依赖软件的MCU方案。将两套复杂的保护电路集成在同一块PCB上，在保证性能的同时，有效控制了产品的体积、重量和成本。
Smart Images
Figure CN224843115U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of battery management technology, specifically to a battery protection circuit with dual protection functions. Background Technology
[0002] In the battery field, battery protection boards typically consist of a detection circuit and a protection circuit for control. When the components of the battery protection board fail, the battery's single protection circuit cannot effectively monitor and protect the battery, resulting in the battery being unable to be used safely and having low reliability.
[0003] Based on this, this utility model designs a battery protection circuit with dual protection functions to solve the above problems. Utility Model Content
[0004] In view of the above-mentioned shortcomings of the existing technology, the present invention provides a battery protection circuit with dual protection functions.
[0005] To achieve the above objectives, this utility model provides the following technical solution: A battery protection circuit with dual protection functions includes a first protection circuit and a second protection circuit; The first protection circuit and the second protection circuit have the same structure and are connected by wired-AND logic. The input module is used to acquire the voltage, current, and temperature signals of the lithium battery. The processing module, electrically connected to the input module, is used to receive and process the acquired signals, and output corresponding switch control signals according to the processing results; The switch module, electrically connected to the processing module, is used to control the on / off state of the lithium battery charging and discharging circuit according to the switch control signal.
[0006] Furthermore, the input module of the first protection circuit includes: A voltage divider resistor network circuit for detecting battery voltage; A sampling resistor and its signal conditioning circuit are used to detect the charging and discharging current. NTC1 is a negative temperature coefficient thermistor used to detect battery temperature. The voltage divider resistor network circuit, the sampling resistor and its signal conditioning circuit, and the negative temperature coefficient thermistor NTC1 are all electrically connected to the processing module of the first protection circuit.
[0007] Furthermore, the input module of the second protection circuit includes: A voltage divider resistor network circuit for detecting battery voltage; A sampling resistor and its signal conditioning circuit are used to detect the charging and discharging current. NTC2 negative temperature coefficient thermistor used to detect battery temperature; The voltage divider resistor network circuit, the sampling resistor and its signal conditioning circuit, and the negative temperature coefficient thermistor NTC2 are all electrically connected to the processing module of the second protection circuit.
[0008] Furthermore, the "wired-AND" logic connection method involves the output pins of the first protection circuit and the second protection circuit being electrically connected through a resistor network circuit.
[0009] Furthermore, the switching module consists of Q1MOS field-effect transistors, Q2MOS field-effect transistors, Q3MOS field-effect transistors, and Q4MOS field-effect transistors.
[0010] Furthermore, Q1MOS, Q2MOS, Q3MOS, and Q4MOS are all N-type MOS field-effect transistors.
[0011] Furthermore, the first protection circuit and the second protection circuit are integrated on the same printed circuit board.
[0012] Compared with the prior art, the advantages of this utility model are as follows: This invention features two independent first and second protection circuits that detect input voltage, current, and temperature signals to determine if the input voltage is too high or too low. This prevents improper use of the battery power supply system when components are damaged, fundamentally eliminating the risk of a single point of failure causing the entire protection system to fail, thus making battery charging and discharging safer. Utilizing dedicated hardware ICs and pure hardware-driven logic, the protection response speed is far faster than software-dependent MCU solutions. Integrating these two complex protection circuits onto a single PCB effectively controls the product's size, weight, and cost while ensuring performance. Attached Figure Description
[0013] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0014] Figure 1 This is a block diagram of a battery protection circuit with dual protection functions according to the present invention; Figure 2 This is the circuit connection diagram of U1 in this utility model; Figure 3 This is the circuit connection diagram of U2 in this utility model; Figure 4 This is a circuit connection diagram of the main switching device of this utility model. Detailed Implementation
[0015] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without creative effort are within the scope of protection of this utility model. Example 1
[0016] In some embodiments, please refer to the appendix to the instruction manual. Figure 1 A battery protection circuit with dual protection functions includes a first protection circuit and a second protection circuit. The first protection circuit and the second protection circuit have the same structure and are connected by wired-AND logic. The input module is used to acquire the voltage, current, and temperature signals of the lithium battery. The processing module, electrically connected to the input module, is used to receive and process the acquired signals, and output corresponding switch control signals according to the processing results; The processing module is the "brain" of the first and second protection circuits, and is implemented by the battery protection ICs (U1, U2); U1 and U2 are dedicated protection ICs with identical functions (e.g., model CW1073AAFS). Processing module functions: Signal processing: The internally integrated ADC converts the analog signals (voltage, temperature) from the input module into digital signals for processing.
[0017] Logical judgment: The IC has preset protection thresholds for overvoltage, undervoltage, overcurrent, short circuit, and overtemperature. It compares the real-time detected value with these thresholds and outputs the corresponding switching control signal based on the comparison result.
[0018] Output control: When any abnormal state is detected, the IC's output pins (DO1 for U1, DO2 for U2) will change from high level to low level, issuing a protection command.
[0019] The switch module, electrically connected to the processing module, is used to control the on / off state of the lithium battery charging and discharging circuit according to the switch control signal.
[0020] Please refer to the instruction manual appendix. Figure 2 and 3The input module of the first protection circuit includes: A voltage divider resistor network circuit for detecting battery voltage; The sampling resistor and its signal conditioning circuit are used to detect the charging and discharging current. When the current flows into the sampling resistor, a voltage will be generated across the sampling resistor. By measuring the voltage across the sampling resistor, the actual resistance value can be determined. In order to increase the stability of the measurement, some filtering is performed, which is the signal conditioning circuit. NTC1 is a negative temperature coefficient thermistor used to detect battery temperature. The voltage divider resistor network circuit, the sampling resistor and its signal conditioning circuit, and the negative temperature coefficient thermistor NTC1 are all electrically connected to the processing module of the first protection circuit.
[0021] The input module of the second protection circuit includes: A voltage divider resistor network circuit for detecting battery voltage; A sampling resistor and its signal conditioning circuit are used to detect the charging and discharging current. NTC2 negative temperature coefficient thermistor used to detect battery temperature; The voltage divider resistor network circuit, the sampling resistor and its signal conditioning circuit, and the negative temperature coefficient thermistor NTC2 are all electrically connected to the processing module of the second protection circuit.
[0022] Each cell voltage (B1-B6) of the battery pack is connected to the voltage detection pins (VCA1-VCA7, VCB1-VCB7) of protection U1 and U2 respectively through two sets of independent voltage divider resistor network circuits (first protection circuit: R1-R7, second protection circuit: R27-R33).
[0023] Function: The voltage divider resistor network circuit proportionally reduces the high voltage of the battery to a range that the internal ADC of the protection IC can safely sample, realizing overvoltage (OV) and undervoltage (UV) detection for each battery cell; Negative temperature coefficient thermistors NTC1 and NTC2 are connected to the temperature detection pins of U1 and U2, respectively.
[0024] Function: The resistance of a negative temperature coefficient thermistor (NTC) decreases as the temperature rises. The protection IC monitors the voltage change across the NTC to determine whether the battery temperature exceeds the safe range, thereby achieving over-temperature (OT) and under-temperature (UT) protection. The wired-AND logic is implemented by electrically connecting the output pins of the first protection circuit and the second protection circuit through a resistor network circuit.
[0025] The switching module consists of Q1MOS field-effect transistor, Q2MOS field-effect transistor, Q3MOS field-effect transistor and Q4MOS field-effect transistor.
[0026] The first layer of protection circuit consists of Q1MOS field-effect transistors and Q2MOS field-effect transistors; The second protection circuit consists of Q3MOS and Q4MOS field-effect transistors.
[0027] In the field-effect transistor with charge protection: Q1MOS, Q2MOS, Q3MOS and Q4MOS are all N-type MOS field-effect transistors.
[0028] The outputs DO1 of U1 and DO2 of U2 are connected together through a resistor network circuit to form a common drive signal node, which is used to control the gate G of the MOS field-effect transistor.
[0029] The resistor network circuit consists of resistors R11, R14, R16, and R45. Resistors R11, R45, and R43 control the on / off states of MOSFETs Q1 and Q2. The resistor network circuit of DO2, through resistors R16, R44, and R46, controls the on / off states of MOSFETs Q3 and Q4.
[0030] The gate of the Q1MOS field-effect transistor is electrically connected to resistors R9 and R45, and the drain of the Q1MOS field-effect transistor is connected to resistor R11. The gate of the Q2MOS field-effect transistor is electrically connected to R43, and its source is connected to the source of the Q1MOS field-effect transistor and grounded through capacitor C8. The gate resistor R14 and resistor R46 of the Q3MOS field-effect transistor are connected, and the drain of the Q3MOS field-effect transistor is electrically connected through resistor R16. The gate of the Q4MOS field-effect transistor is electrically connected via resistor R44, and the source of the Q4MOS field-effect transistor is connected to the source of the Q3MOS field-effect transistor and grounded via capacitor C10. Working principle: Normal state: When the battery is in normal condition, both DO1 pin of U1 and DO2 pin of U2 output a high level. At this time, the drive node is at a high level, the MOSFET is turned on, and the charging and discharging circuit is working normally.
[0031] Abnormal state: When any protection IC (e.g., U1) detects an abnormality, its DO1 pin will go low. This low level will pull the potential of the entire drive node low through the resistor network circuit, causing all MOSFETs to turn off immediately, thereby cutting off the charging and discharging circuit.
[0032] Fault tolerance: Even if U1 fails completely (e.g., the DO1 pin is stuck at a high level), as long as U2 functions normally, it can still force the entire system's MOS field-effect transistors to shut down by pulling DO2 low, thus achieving protection and high reliability.
[0033] The first protection circuit and the second protection circuit are integrated on the same printed circuit board.
[0034] Workflow Example Taking over-voltage protection as an example, its complete workflow is as follows: Detection: The voltage of a certain cell in the battery pack (e.g., B6) is too high. This voltage is divided by voltage divider resistors R1 and R2 and then input to the VCA6 pin of U1.
[0035] Judgment: The comparator inside U1 detected that the voltage at the VCA6 pin exceeded the preset overvoltage protection threshold.
[0036] Decision: The internal logic circuit of U1 determines that overvoltage protection needs to be implemented.
[0037] Execution: The DO1 pin of U1 immediately switches from high level to low level.
[0038] Drive: The low level of DO1 pulls down the gate potential of Q1MOS and Q2MOS through resistors R11 and R14.
[0039] Protection activated: Q1 MOSFET and Q2 MOSFET are turned off, the charging circuit is cut off, and the battery stops charging, thus avoiding damage or safety risks caused by overvoltage. During this process, the state of U2 does not affect the final protection action.
[0040] The workflow of other protection modes such as overcurrent, short circuit, and overtemperature is similar to the above process, all following the path of "detection -> judgment -> output low level -> wired-AND logic drive -> MOSFET turn-off".
[0041] Two independent first and second protection circuits detect input voltage, current, and temperature signals to determine if the input voltage is too high or too low. This prevents improper use of the battery power supply system when components fail, fundamentally eliminating the risk of a single point of failure causing the entire protection system to fail, thus making battery charging and discharging safer. Using dedicated hardware ICs and pure hardware-driven logic, the protection response speed is far faster than software-dependent MCU solutions. Integrating these two complex protection circuits onto a single PCB effectively controls the product's size, weight, and cost while ensuring performance.
[0042] The above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.
Claims
1. A battery protection circuit with dual protection functions, comprising a first protection circuit and a second protection circuit, characterized in that: The first protection circuit and the second protection circuit have the same structure and are connected by "wired-AND" logic. The input module is used to acquire the voltage, current, and temperature signals of the lithium battery. The processing module, electrically connected to the input module, is used to receive and process the acquired signals, and output corresponding switch control signals according to the processing results; The switch module, electrically connected to the processing module, is used to control the on / off state of the lithium battery charging and discharging circuit according to the switch control signal.
2. The battery protection circuit with dual protection function according to claim 1, characterized in that, The input module of the first protection circuit includes: A voltage divider resistor network circuit for detecting battery voltage; A sampling resistor and its signal conditioning circuit are used to detect the charging and discharging current. NTC1 is a negative temperature coefficient thermistor used to detect battery temperature. The voltage divider resistor network circuit, the sampling resistor and its signal conditioning circuit, and the negative temperature coefficient thermistor NTC1 are all electrically connected to the processing module of the first protection circuit.
3. The battery protection circuit with dual protection function according to claim 1, characterized in that, The input module of the second protection circuit includes: A voltage divider resistor network circuit for detecting battery voltage; A sampling resistor and its signal conditioning circuit are used to detect the charging and discharging current. NTC2 negative temperature coefficient thermistor used to detect battery temperature; The voltage divider resistor network circuit, the sampling resistor and its signal conditioning circuit, and the negative temperature coefficient thermistor NTC2 are all electrically connected to the processing module of the second protection circuit.
4. The battery protection circuit with dual protection function according to claim 2 or 3, characterized in that, The "wired-AND" logic connection method is that the output pins of the first protection circuit and the second protection circuit are electrically connected through a resistor network circuit.
5. The battery protection circuit with dual protection function according to claim 4, characterized in that, The switching module consists of Q1MOS field-effect transistor, Q2MOS field-effect transistor, Q3MOS field-effect transistor and Q4MOS field-effect transistor.
6. The battery protection circuit with dual protection function according to claim 5, characterized in that, Q1MOS, Q2MOS, Q3MOS and Q4MOS are all N-type MOS field-effect transistors.
7. The battery protection circuit with dual protection function according to claim 1, characterized in that, The first protection circuit and the second protection circuit are integrated on the same printed circuit board.