Lithium battery protection system for electronic cigarette

Abstract

The utility model belongs to the technical field of electronic cigarettes, and discloses a lithium battery protection system for an electronic cigarette, which comprises a main control chip used for receiving external signals and controlling the system to operate; the step-down charging circuit is connected to the external power supply input end and the lithium battery, is used for charging the lithium battery and is controlled by the main control chip; the current monitoring circuit is connected between the lithium battery and a load and is used for monitoring current flowing through the lithium battery and outputting a current signal to the main control chip; the NTC temperature measurement module is tightly attached to the lithium battery and is used for measuring the temperature of the lithium battery and outputting a temperature signal to the main control chip; and the battery positive electrode control module is connected between the positive electrode of the lithium battery and the load, is used for controlling on-off of power supply of the lithium battery to the load, and is controlled by the main control chip. According to the utility model, the voltage, current and temperature of the battery can be monitored in real time, and the lithium battery can be quickly protected when abnormal conditions such as overvoltage, overcurrent and over-temperature occur.

Description

A lithium battery protection system for electronic cigarettes Technical Field

[0001] This utility model belongs to the field of electronic cigarette technology, and specifically relates to a lithium battery protection system for electronic cigarettes. Background Technology

[0002] Electronic cigarettes are typically powered by lithium batteries. Lithium batteries pose safety hazards during use, such as overcharging, over-discharging, overheating, and short circuits. These hazards can lead to shortened battery life, decreased performance, and even serious accidents such as battery swelling, leakage, or explosion.

[0003] Most existing protection solutions for lithium batteries in e-cigarettes are relatively simple, typically relying on the detection of only a single parameter, such as determining the charge / discharge state solely through a voltage threshold or simply monitoring temperature. These solutions lack comprehensive, real-time monitoring and overall protection for the dynamic changes in voltage, current, and temperature during battery charging and discharging.

[0004] For example, existing technologies have the following problems:

[0005] 1. Under high temperature conditions, lithium batteries in electronic cigarettes are prone to swelling or explosion.

[0006] 2. Forcibly discharging the battery when it is low may cause irreversible damage to its lifespan.

[0007] 3. Many existing electronic cigarette products on the market, especially low-cost products, lack or have incomplete lithium battery protection systems.

[0008] 4. While some existing charging management ICs are feature-rich, they are also expensive, which hinders the widespread adoption of e-cigarette products.

[0009] 5. There is a lack of a solution that can combine multiple key parameters such as battery voltage (monitored via input voltage), current, and temperature for overall, dynamic protection.

[0010] 6. Traditional voltage and current measurement methods, such as using a sampling resistor in conjunction with an ADC, result in significant power consumption on the sampling resistor when the current is large, leading to energy loss and heat generation.

[0011] Therefore, there is an urgent need for a protection system that can effectively address the safety hazards of lithium batteries in e-cigarettes. Summary of the Invention

[0012] This invention aims to at least partially solve the aforementioned technical problems. Therefore, the purpose of this invention is to provide a lithium battery protection system for electronic cigarettes, capable of real-time monitoring of battery voltage (indirectly or directly via input voltage), current, and temperature, and rapidly providing protection in the event of abnormal conditions such as overvoltage, overcurrent, or overtemperature, while also being cost-effective and employing a low-power current measurement method.

[0013] The technical solution adopted in this utility model is as follows:

[0014] A lithium battery protection system for electronic cigarettes, comprising:

[0015] The main control chip is used to receive external signals and control the system operation.

[0016] A step-down charging circuit is connected to an external power input terminal and a lithium battery to charge the lithium battery and is controlled by the main control chip.

[0017] A current monitoring circuit is connected between the lithium battery and the load to monitor the current flowing through the lithium battery and output the current signal to the main control chip.

[0018] The NTC temperature measurement module is positioned close to the lithium battery to measure its temperature and output the temperature signal to the main control chip.

[0019] The battery positive terminal control module is connected between the positive terminal of the lithium battery and the load. It is used to control the on / off state of the lithium battery supplying power to the load and is controlled by the main control chip.

[0020] Preferably, the main control chip is configured as follows:

[0021] Monitor the input voltage at the external power input terminal, and when the input voltage exceeds a preset first voltage threshold, control the buck charging circuit to turn off;

[0022] The system receives the current signal output by the current monitoring circuit, and when the current indicated by the current signal exceeds a preset first current threshold, it controls the battery positive electrode control module to shut down.

[0023] The system receives the temperature signal output by the NTC temperature measurement module. When the temperature indicated by the temperature signal exceeds a preset first temperature threshold, it controls the buck charging circuit and the battery positive terminal control module to shut down.

[0024] Preferably, the main control chip is further configured to: when the input voltage, the current indicated by the current signal, and the temperature indicated by the temperature signal all return to a safe range, re-control the buck charging circuit and / or the battery positive electrode control module to start.

[0025] Preferably, the first voltage threshold is 20V; the first current threshold is 8A.

[0026] Preferably, the current monitoring circuit includes a Hall effect current sensor. The Hall effect current sensor is model ACS712ELCTR.

[0027] Preferably, the NTC temperature measurement module includes a voltage divider circuit composed of a thermistor and a resistor.

[0028] Preferably, the step-down charging circuit includes an inductor, a diode, a P-type field-effect transistor, and a filter capacitor, forming a BUCK step-down circuit.

[0029] Preferably, the battery positive electrode control module includes a switching circuit for driving a P-channel MOSFET to control the on / off state of the P-channel MOSFET, thereby controlling the connection from the lithium battery positive electrode to the load. The switching circuit for driving the P-channel MOSFET includes an NPN transistor and a resistor.

[0030] The beneficial effects of this utility model are as follows:

[0031] 1. By integrating functions such as lithium battery protection main control, charging circuit control, over-temperature protection, over-current protection, and input over-voltage protection, the overall system cost is reduced.

[0032] 2. It realizes the joint monitoring and real-time dynamic protection of multiple parameters such as voltage (input), current, and temperature. It can respond quickly when abnormal conditions occur and automatically resume operation when the parameters return to normal, thus improving the system's safety and user experience.

[0033] 3. Overcurrent protection is achieved by using a Hall effect-based current monitoring circuit, which avoids the power consumption loss at high currents when using sampling resistors for current measurement, thus improving efficiency.

[0034] 4. The battery positive terminal control module can quickly cut off the power supply from the battery to the downstream circuit when an abnormality is detected, effectively protecting components such as the heating element and the microcontroller.

[0035] 5. This system can effectively solve the safety hazards of overcharging, overheating, overcurrent and input overvoltage of electronic cigarette lithium batteries during charging and discharging, thus improving the safety and reliability of the product. Attached Figure Description

[0036] Figure 1 is a circuit diagram of the lithium battery protection system for electronic cigarettes according to this invention. Detailed Implementation

[0037] The technical solution of this utility model will now be clearly and completely described 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.

[0038] It should be understood that, and also noted, in the embodiments, the functions / actions may appear in a different order than those shown in the figures. For example, depending on the functions / actions involved, they may actually be performed substantially concurrently, or sometimes the two figures shown consecutively may be performed in reverse order.

[0039] As shown in Figure 1, this embodiment of a lithium battery protection system for electronic cigarettes mainly includes a main control chip, a step-down charging circuit, a current monitoring circuit, an NTC temperature measurement module, and a battery positive electrode control module. The main control chip can be a microcontroller (MCU) or other suitable digital or analog control chip. The main control chip is the core of the system, responsible for collecting various sensor signals and making judgments and controlling outputs according to preset logic.

[0040] The buck charging circuit connects to the external charging interface of the e-cigarette (e.g., Type-C port) and the lithium battery. This circuit uses a buck topology and consists of an inductor L1, a diode D1, a P-type MOSFET, and several energy storage and filtering capacitors. An external power supply (typically 5V) is input through the Type-C port, and the buck circuit steps it down to a voltage suitable for charging the lithium battery (approximately 4.2V). The main control chip controls the switching of the P-type MOSFET in the buck circuit to turn the charging process on or off. Furthermore, the main control chip monitors the input voltage of the Type-C port, for example, through the output voltage signal of an overvoltage monitoring circuit. When the input voltage exceeds a preset first voltage threshold (e.g., 20V), the main control chip immediately shuts down the buck charging circuit to achieve input overvoltage protection.

[0041] The current monitoring circuit is connected between the lithium battery and the e-cigarette load (including the e-cigarette's heating coil). This circuit uses a Hall effect-based current sensor, such as the ACS712ELCTR chip, along with components like capacitor C2. The ACS712ELCTR chip contains a Hall effect device. When current flows through its internal copper conductive path (IP+ and IP- pins), a magnetic field is generated. This magnetic field is sensed by the Hall effect device and converted into a proportional voltage output. This output voltage signal reflects the magnitude of the current flowing through the BAT+ node to VCC. The current monitoring circuit inputs this proportional voltage signal (e.g., after appropriate conditioning) to the ADC port of the main control chip. The main control chip reads this ADC data in real time and converts it into a current value. When the monitored current exceeds a preset first current threshold (e.g., 8A), the main control chip determines that an overcurrent has occurred and quickly controls the battery positive terminal control module to shut down, cutting off the power supply from the battery to the load, thereby achieving overcurrent protection and protecting the downstream circuitry and battery safety. Compared to the traditional method of calculating current by measuring voltage drop through sampling resistors, Hall effect current sensors are isolated and have extremely low power consumption when carrying large currents, significantly reducing energy loss.

[0042] The NTC temperature measurement module is positioned close to the lithium battery body to accurately measure its surface temperature. This module consists of a voltage divider circuit formed by a thermistor R18 (NTC) and a fixed resistor R19. The resistance of the NTC resistor changes with temperature (typically a negative temperature coefficient, meaning its resistance decreases as temperature increases). The voltage divider circuit is powered by a fixed voltage, with the thermistor R18 and fixed resistor R19 connected in series. The voltage divider outputs a voltage signal that varies with temperature. This voltage signal is input to the ADC port of the main control chip. The main control chip reads this ADC data and converts it into a battery temperature value through table lookup or calculation. When the monitored battery temperature exceeds a preset first temperature threshold, the main control chip determines that the lithium battery is overheating. It immediately controls the buck charging circuit to shut down (stop charging) and simultaneously controls the battery positive terminal control module to shut down, cutting off the battery power supply and achieving over-temperature protection to prevent the battery from becoming dangerous due to high temperature.

[0043] The battery positive terminal control module is connected between the lithium battery positive terminal (BAT+ node) and the electronic cigarette load. This module consists of a P-channel MOSFET and a switching circuit to drive it. For example, the NPN transistor switching circuit comprises an NPN transistor Q2 and multiple resistors R14, R15, R13, and R16. This switching circuit controls the gate (G) voltage of the P-channel MOSFET, thereby controlling the on / off state between its drain (D) and source (S). When the main control chip outputs a control signal to turn on the NPN transistor, the gate of the P-channel MOSFET is pulled low, the MOSFET conducts, and the lithium battery positive terminal is connected to the load. When the main control chip outputs a control signal to turn off the NPN transistor, the gate of the P-channel MOSFET is pulled high, the MOSFET is turned off, and the connection between the lithium battery positive terminal and the load is severed. This module can quickly respond to the control signals of the main control chip, rapidly cutting off the battery power supply. It is used to implement power-off functions for overcurrent and overtemperature protection, effectively protecting all components and circuits downstream of the BAT+ node.

[0044] The main control chip also features dynamic recovery functionality. When overvoltage, overcurrent, or overtemperature protection trips, the main controller continuously monitors the corresponding parameters. When the parameters that triggered the protection (input voltage, current, temperature) return to safe ranges (e.g., below the threshold for deactivating protection), the main controller will reopen the buck charging circuit (if it was previously in charging mode) and / or the battery positive terminal control module (to restore battery power), allowing the e-cigarette to return to normal operation or charging mode.

[0045] In practical applications, the main control chip can monitor the lithium battery voltage in real time (e.g., by connecting to the battery positive terminal and performing ADC sampling). When the lithium battery voltage falls below a preset second voltage threshold (over-discharge protection voltage), it controls the battery positive terminal control module to shut down and stop discharging, thus protecting the lithium battery from over-discharge damage. When a charger is connected, the main control chip detects the charging input, allowing the buck charging circuit to operate, and releases the over-discharge protection state once the battery voltage returns to a safe range.

[0046] This utility model's electronic cigarette lithium battery protection system, through the coordinated work of the above modules, achieves comprehensive and real-time monitoring and protection of the lithium battery charging and discharging process, effectively solving multiple safety hazards in the use of electronic cigarettes, improving the safety and reliability of the product, and also has cost and power consumption advantages.

[0047] This utility model is not limited to the above-mentioned optional embodiments. Anyone can derive other forms of products under the guidance of this utility model. However, regardless of any changes made in its shape or structure, any technical solution that falls within the scope of the claims of this utility model shall be protected by this utility model.

Claims

1. A lithium battery protection system for electronic cigarettes, characterized in that, include: The system includes a main control chip for receiving external signals and controlling system operation; a step-down charging circuit connected to the external power input and the lithium battery for charging the lithium battery, and controlled by the main control chip; a current monitoring circuit connected between the lithium battery and the load for monitoring the current flowing through the lithium battery and outputting the current signal to the main control chip; an NTC temperature measurement module positioned close to the lithium battery for measuring the temperature of the lithium battery and outputting the temperature signal to the main control chip; and a battery positive terminal control module connected between the positive terminal of the lithium battery and the load for controlling the on / off supply of power from the lithium battery to the load, and controlled by the main control chip.

2. The lithium battery protection system according to claim 1, characterized in that, The main control chip is configured to monitor the input voltage at the external power input terminal, and when the input voltage exceeds a preset first voltage threshold, control the buck charging circuit to shut down. The system receives the current signal output by the current monitoring circuit, and controls the battery positive electrode control module to shut down when the current indicated by the current signal exceeds a preset first current threshold; it also receives the temperature signal output by the NTC temperature measurement module, and controls the buck charging circuit and the battery positive electrode control module to shut down when the temperature indicated by the temperature signal exceeds a preset first temperature threshold.

3. The lithium battery protection system according to claim 2, characterized in that, The main control chip is also configured to: when the input voltage, the current indicated by the current signal, and the temperature indicated by the temperature signal all return to a safe range, re-control the buck charging circuit and / or the battery positive electrode control module to start.

4. The lithium battery protection system according to claim 2, characterized in that: The first voltage threshold is 20V; the first current threshold is 8A.

5. The lithium battery protection system according to claim 1, characterized in that: The current monitoring circuit includes a Hall effect current sensor.

6. The lithium battery protection system according to claim 5, characterized in that: The Hall effect current sensor is model ACS712ELCTR.

7. The lithium battery protection system according to claim 1, characterized in that: The NTC temperature measurement module includes a voltage divider circuit composed of a thermistor and a resistor.

8. The lithium battery protection system according to claim 1, characterized in that: The step-down charging circuit includes an inductor, a diode, a P-type field-effect transistor, and a filter capacitor, forming a BUCK step-down circuit.

9. The lithium battery protection system according to claim 1, characterized in that: The battery positive electrode control module includes a switching circuit for driving a P-channel MOSFET to control the on / off state of the P-channel MOSFET, thereby controlling the connection between the lithium battery positive electrode and the load.

10. The lithium battery protection system according to claim 9, characterized in that: The switching circuit for driving the P-channel MOS transistor includes an NPN transistor and a resistor.

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