HNB device, and protection circuit for HNB device

Abstract

The present invention pertains to the technical field of HNB devices and provides a HNB device and a protection circuit for the HNB device. The protection circuit includes a first switch module, a second switch module, a voltage acquisition module, and an overcurrent protection module. When the second switch module is in a switched-on state, the first switch module causes the heating circuit to heat when receiving a PWM control signal, and adjusts a magnitude of a current flowing through the heating circuit according to the PWM control signal. When the overcurrent protection module outputs a switching-off control signal to the second switch module to cut off the heating circuit when detecting a overcurrent in the heating circuit based on a sensing voltage output by the voltage acquisition module. The technical solution of the present invention has solved a problem of potential failure due to software protection in the existing HNB devices. By utilizing a hardware-level protection mechanism, a safety and a stability of the HNB device are improved, and a risk of malfunction of the HNB device is reduced.

Description

TECHNICAL FIELD

[0001] The present invention pertains to the technical field of HNB devices, and more particularly, to a HNB device and a protection circuit for HNB device.BACKGROUND

[0002] HNB (Heat-Not-Burn) technology is gradually emerging as a technological trend in products of electronic cigarettes and HNB devices. These products aim to reduce harmful substances generated during combustion of traditional tobacco by heating rather than burning, thereby reducing health risks for users. In existing HNB devices, an operation of a protection circuit generally relies on software control. When software is exceptional or fails to respond promptly, failure of protection mechanism may be caused. Accordingly, an occurrence of equipment damage or safety accident cannot be effectively avoided.SUMMARY

[0003] It is an objective of the present invention to provide a HNB device and a protection circuit for the HNB device, so as to solve the problem in the related art that failure of protection mechanism may be caused when software is exceptional or fails to respond promptly, and an occurrence of equipment damage or safety accident cannot be effectively avoided accordingly.

[0004] To achieve the above objective, the invention is set out in the appended set of claims.

[0005] The embodiments of the present invention have the following technical effects: by introducing the protection circuit into the technical solution of the present invention, the problem of potential failure caused by software-initiated overcurrent protection in the existing HNB device has been solved. This hardware protection circuit incorporates the first switch module, the second switch module, the voltage acquisition module, and the overcurrent protection module to achieve a more reliable overcurrent protection mechanism.BRIEF DESCRIPTION OF DRAWINGS

[0006] In order to describe the technical solutions in the embodiments of the present invention more clearly, a brief introduction regarding the accompanying drawings that need to be used for describing the embodiments of the present invention is given below. FIG. 1 is a schematic diagram illustrating a first structure of a protection circuit for a HNB device in the first embodiment of the present invention; FIG. 2 is a schematic diagram illustrating a second structure of the protection circuit for the HNB device in the first embodiment of the present invention; FIG. 3 is a schematic diagram illustrating a third structure of the protection circuit for the HNB device in the first embodiment of the present invention; FIG. 4 is a first circuit diagram of the protection circuit for the HNB device in the first embodiment of the present invention; FIG. 5 is a diagram illustrating a current flow of a heating circuit of the protection circuit for the HNB device in the first embodiment of the present invention; FIG. 6 is a schematic diagram illustrating a fourth structure of the protection circuit for the HNB device in the second embodiment of the present invention; FIG. 7 is a schematic diagram illustrating a fifth structure of the protection circuit for the HNB device in the second embodiment of the present invention; FIG. 8 is a schematic diagram illustrating a sixth structure of the protection circuit for the HNB appliance in the second embodiment of the present invention; FIG. 9 is the second circuit diagram of the protection circuit for an HNB device in the second embodiment of the present invention; FIG. 10 is a third circuit diagram of the protection circuit for the HNB device in the second embodiment of the present invention. DETAILED DESCRIPTIOIN OF EMBODIMENTS

[0007] The technical solutions in the embodiments of the present invention will be described clearly and comprehensively hereinafter.

[0008] In some embodiments, as shown in FIG. 1, a protection circuit for a HNB device is provided. The HNB device includes a heating element 102, and the protection circuit includes a first switch module 101, a second switch module 103, a voltage acquisition module 104, and an overcurrent protection module 105. The heating element 102, the first switch module 101, the second switch module 103, and the voltage acquisition module 104 are constituted as a first heating circuit. The second switch module 103 and the voltage acquisition module 104 are respectively connected to the overcurrent protection module 105. In a case where the second switch module 103 is in a switched-on state, when the first switch module 101 receives a PWM control signal, the first switch module 101 causes the first heating circuit to perform heating and adjusts a magnitude of a current flowing through the first heating circuit according to the PWM control signal. When the overcurrent protection module 105 detects an overcurrent in the first heating circuit based on a sensing voltage output by the voltage acquisition module 104, the overcurrent protection module 105 outputs a switching-off control signal to the second switch module 103 to cut off the first heating circuit.

[0009] The first switch module 101 controls conduction and cutting off of the first heating circuit. The first switch module 101 adjusts the current magnitude by receiving a pulse width modulation (PWM) control signal, and the first switch module 101 and the heating element 102 are constituted as the first heating circuit. The second switch module 103 is connected to the overcurrent protection module 105 and is used to cut off the current of the first heating circuit when the overcurrent protection module 105 sends a switching-off control signal, thereby preventing an overcurrent condition from occurring continuously. A switching-on state or a switching-off state of the second switch module 103 controls whether the first heating circuit can operate normally. The voltage acquisition module 104 monitors the voltage of the first heating circuit in real time. By monitoring the voltage through the voltage acquisition module 104, a current change can be detected, and whether the first heating circuit is in an overcurrent state can be detected accordingly. The voltage acquisition module 104 transmits voltage information to the overcurrent protection module 105 as the basis for determining overcurrent. The overcurrent protection module 105 determines whether the current in the first heating circuit is overcurrent based on the voltage information provided by the voltage acquisition module 104. When the detected voltage value indicates that the current exceeds a predetermined safety range, the overcurrent protection module 105 immediately outputs a switching-off control signal to the second switch module 103 to cut off the first heating circuit, thereby preventing the heating element 102 from being damaged due to overcurrent.

[0010] The working process of the protection circuit for the HNB device in this embodiment is described as follows: under normal operating condition, the first switch module 101 adjusts the current in the first heating circuit according to the received PWM control signal. By adjusting a duty ratio of the PWM signal, the current flowing through the heating element 102 can be precisely controlled, and a heating effect of the heating element 102 is adjusted accordingly. The voltage acquisition module 104 acquires a voltage signal in the first heating circuit in real time and transmits the sensing voltage signal to the overcurrent protection module 105. The overcurrent protection module 105 detects a change in current through the voltage signal and monitors whether an overcurrent phenomenon occurs. When the overcurrent protection module 105 detects that the current in the first heating circuit exceeds the safety range, based on the determination of the voltage signal, the overcurrent protection module 105 immediately outputs a switching-off control signal to the second switch module 103. When receiving the switching-off control signal, the second switch module 103 quickly cuts off the first heating circuit, stops the operation of the heating element 102, thereby preventing a damage to the HNB device or an occurrence of potential safety hazards caused by overcurrent. Once the overcurrent protection mechanism is triggered, normal operation of the HNB device can be restored through a restart mechanism, or manual reset may be required to ensure safe operation of the system again.

[0011] It should be noted that the first switch module 101 usually adopts semiconductor devices such as metal-oxide-semiconductor field-effect transistors (Metal-Oxide-Semiconductor Field-Effect Transistors, MOSFETs) or insulated gate bipolar transistors (Insulated Gate Bipolar Transistors, IGBTs), which can regulate current flow based on the PWM control signal. By adjusting the duty ratio of the PWM control signal, a switching frequency and a conduction time of the MOSFET or the IGBT can precisely adjust the current for heating to ensure that a power output of the heating element 102 meets the expectations. The second switch module 103 can use MOSFETs or IGBTs similar to those in the first switch module 101. Or alternatively, the second switch module 103 can select to use relays or solid-state relays (SSRs) as switching elements. The switching-on and switching-off of the second switch module 103 is driven by the switching-off control signal from the overcurrent protection module 105. when a condition of overcurrent is detected, the overcurrent protection module 105 sends a cutoff signal, the second switch module 103 cuts off the first heating circuit to quickly cut off the current, thereby ensuring safety. The voltage acquisition module 104 is usually consisted of a voltage divider or a current sensor (e.g., a Hall sensor or a shunt resistor). The voltage divider or the sensor acquires and outputs the voltage signal from the first heating circuit. The overcurrent protection module 105 usually includes a comparator and a drive circuit. The comparator compares the sensing voltage signal with a preset safety threshold, when the voltage exceeds the preset safety threshold, a control logic unit is triggered to make a determination. The drive circuit is used to transmit the overcurrent protection signal to the second switch module 103 to perform a cutoff operation. The overcurrent protection module 105 utilizes the comparator to analyze the voltage signal to determine whether the current exceeds the safety range. If an overcurrent occurs, the overcurrent protection module 105 generates a cutoff signal through the control logic unit, and the drive circuit transmits the cutoff signal to the second switch module 103, thereby cutting off the first heating circuit.

[0012] The technical effects of the protection circuit for the HNB device in this embodiment are summarized as follows: the technical solution of the present invention has solved the technical problem of potential failure caused by software-initiated overcurrent protection in the existing HNB device by introducing a protection circuit. This hardware protection circuit incorporates the first switch module, the second switch module, the voltage acquisition module and the overcurrent protection module to achieve a more reliable overcurrent protection mechanism. When the first heating circuit is operating, the first switch module adjusts the magnitude of current according to the PWM control signal, while the voltage acquisition module continuously monitors voltage change. In the event of the overcurrent, the overcurrent protection module immediately outputs the cutoff signal to the second switch module to quickly cut off the first heating circuit, thereby avoiding the damage to the HNB device and the occurrence of potential safety hazards. By virtue of this hardware-level protection mechanism, the safety and the stability of the HNB device are improved, and the risk of malfunction of the HNB device is reduced accordingly.

[0013] As an implementation method, as shown in FIG. 2, the overcurrent protection module 105 includes a comparison module 111 and a third switch module 112. An input of the comparison module 111 is connected to the output of the voltage acquisition module 104, and an output of the comparison module 111 is connected to the control end of the third switch module 112. A first end of the third switch module 112 is connected to the control end of the second switch module 103, and a second end of the third switch module 112 is grounded. The comparison module 111 outputs a switching-on control signal to the third switch module 112 when detecting that the sensing voltage is greater than the reference voltage. When the third switch module 112 is switched-on, switching-on of the third switch module 112 enables the control end of the second switch module 103 be grounded. Accordingly, a switching-off control signal is sent to the second switch module 103.

[0014] The main function of the comparison module 111 is comparing the voltage signal (sensing voltage) output by the voltage acquisition module 104 with a preset reference voltage. When the sensing voltage is greater than the reference voltage, the comparison module 111 outputs a switching-on control signal to the third switch module 112. The comparison module 111 serves as overcurrent detection function and is a core component in the overcurrent protection circuit. The comparison module 111 generally applies an operational amplifier or a comparator, is provided with high-precision voltage comparison capability. The main function of the third switch module 112 is controlling switching-off of the second switch module 103. When the comparison module 111 detects that the sensing voltage is greater than the reference voltage, the third switch module 112 is switched-on to make the control end of the second switch module 103 be grounded, thereby cutting off the second switch module 103 from the circuit, cutting off the current in the first heating circuit, and preventing overcurrent phenomenon. The working process of this technical solution of the present invention is described as follows: the voltage acquisition module 104 monitors the voltage in the first heating circuit in real time and transmits the voltage signal to the comparison module 111. The comparison module 111 compares the received sensing voltage with the preset reference voltage. When the sensing voltage exceeds the reference voltage, it indicates that an overcurrent is generated in the first heating circuit. At this time, the comparison module 111 outputs a switching-on control signal indicating the overcurrent to the third switch module 112. After receiving the switching-on control signal from the comparison module 111, the third switch module 112 is switched-on and makes the control end of the second switch module 103 be grounded, thereby enabling the second switch module 103 to receive a switching-off control signal. After receiving the switching-off control signal, the second switch module 103 quickly cuts off the first heating circuit, cuts off the current flow and thereby preventing the damage to the HNB device or occurrence of safety hazards caused by overcurrent.

[0015] The technical effects of the protection circuit for the HNB device in this embodiment are summarized as follows: by applying this technical solution, the protection circuit can be cut off timely in hardware level manner when an overcurrent occurs in the first heating circuit, thereby effectively protecting the HNB device from damage. Compared to the conventional software control methods, this technical solution can significantly improve the response speed and the stability of overcurrent protection. The cooperative operation of the comparison module 111, the third switch module 112, and the second switch module 103 ensures that a response can be made immediately and the current can be cut off when an overcurrent condition occurs, and thus the safety of the device is ensured.

[0016] As an implementation method, as shown in FIG. 3, the protection circuit further includes a first control module 106 which is respectively connected to the control end of the first switch module 101, the control end of the second switch module 103, and the output of the comparison module 111. The first control module 106 is configured to output a high-level signal to the second switch module 103 to turn on the second switch module 103, output a PWM control signal to the first switch module 101, and receive the switching-on control signal output by the comparison module 111.

[0017] The first control module 106 outputs a high-level signal to the second switch module 103 to turn on the second switch module 103, thereby allowing current to flow through the first heating circuit. When normal heating is required, the first control module 106 ensures that the second switch module 103 to be switched-on, thereby allowing current to flow into the heating element 102. The first control module 106 provides a PWM control signal to the first switch module 101, the magnitude of current in the first heating circuit is adjusted by adjusting a duty ratio of the PWM control signal. This enables precise control of the power output of the heating element 102, ensuring the stability and efficiency of the heating process. The first control module 106 receives a switching-on control signal output from the comparison module 111, this switching-on control signal is triggered when the current in the first heating circuit exceeds the safety threshold. When overcurrent occurs, the first control module 106 receives the switching-on control signal from the comparison module 111, obtain information indicating that the first heating circuit has been switched off and there is no need to cut off the first heating circuit using software.

[0018] The technical effects of the protection circuit for the HNB device in this embodiment are described as follows: overcurrent protection is achieved through hardware, the dependence on software for cutting off the first heating circuit is avoided, the system's response speed and reliability are improved accordingly. The first control module 106 outputs a high-level signal to the second switch module 103 to ensure the stability of the first heating circuit during normal operation, and precisely adjusts a power output of the heating element 102 through the PWM control signal, thereby achieving an efficient and stable heating process. When an overcurrent condition occurs, the first control module 106 promptly cuts off the first heating circuit according to the switching-on control signal from the comparison module 111, thereby avoiding damage to the HNB device due to overcurrent. This technical solution enhances a degree of automation of overcurrent protection, reduces the risk of system failure, and eliminates the need for software intervention when the overcurrent occurs, thereby ensuring higher safety and faster response time.

[0019] As an implementation method, the first control module 106 is connected to a voltage input of the comparison module 111 to output a reference voltage to the comparison module.

[0020] The first control module 106 is further connected to the battery module. The first control module 106 is connected to the voltage input of the comparison module 111 and dynamically outputs different reference voltages according to a battery SOC state: when the battery SOC is lower than a first preset value (e.g., SOC < 20%): the reference voltage is reduced to make the overcurrent protection more sensitive. In this way, the heating power can be constrained in advance under low battery level condition, over-discharge is avoided, and battery life is prolonged. When the SOC is greater than a second preset value (e.g., SOC >90%): the reference voltage is appropriately increased to reduce frequent shutdowns caused by misjudgments. In this way, when the battery is fully charged, the heating current can be appropriately increased to improve a heating efficiency. Regarding a normal battery level, the SOC is between the first preset value and the second preset value (i.e., the SOC is between 20% and 90%), the overcurrent protection threshold remains at a standard level, and normal operation is performed according to load requirement.

[0021] As an implementation method, the overcurrent protection module 105 further includes a first overcurrent protection module and a second overcurrent protection module. Two inputs of the first overcurrent protection module receive the sensing voltage and a first reference voltage respectively, an output of the first overcurrent protection module is connected to the first control module 106 and the second switch module 103. Two inputs of the second overcurrent protection module receive the sensing voltage and a second reference voltage respectively, and an output of the second overcurrent protection module is connected to the first control module 106 and the second switch module 103. The first reference voltage is greater than the second reference voltage. When the first control module 106 detects that both the first overcurrent protection module and the second overcurrent protection module output overcurrent signals, the first control module 106 determines that the first heating circuit has severe overcurrent and sends an overcurrent prompt. When the first control module 106 detects that the first overcurrent protection module does not output an overcurrent signal, but the second overcurrent protection module outputs an overcurrent signal, the first control module 106 determines that the first heating circuit has slight overcurrent, re-enables the second switch module to reduce the duty ratio of the PWM control signal of the first switch module 101 until the second overcurrent protection module does not output an overcurrent signal.

[0022] The first overcurrent protection module and the second overcurrent protection module detect and respond to different degrees of overcurrent in the first heating circuit, thereby achieving more precise overcurrent management. The management process is described as follows: 1. Handling of slight overcurrent: only when the second overcurrent protection module detects an overcurrent (e.g., the sensing voltage exceeds the second reference voltage but does not exceed the first reference voltage), the first control module 106 will reduce a duty ratio of the PWM control signal, gradually decrease the heating power, and restart the second switch module 103 to ensure that the current restores to a the safety range before normal operation. 2. Severe overcurrent handling: when both the first overcurrent protection module and the second overcurrent protection module detect an overcurrent (i.e., the sensing voltage exceeds the first reference voltage), the first control module 106 determines the overcurrent as a severe overcurrent, immediately switches off the second switch module 103, and sends an overcurrent prompt to prevent damage to the circuit. 3. Dynamic adjustment and self-recovery mechanism: in case of slight overcurrent, the first control module 106 gradually reduces duty ratio of the PWM control signal until the second overcurrent protection module stops outputting the overcurrent signal. Thus, dynamic adjustment is achieved, false trigger is avoided, and the loss to the heating element is reduced.

[0023] The technical effects of this embodiment are summarized as follows: false trigger due to instantaneous current fluctuations is avoided, the stability of the device is improved; severe overcurrent is cut off immediately, circuit overheating or component damage is avoided; high current impact is reduced by gradually adjusting the duty ratio of the PWM control signal, the service life of heating element is prolonged; automatic recovery from slight overcurrent is supported, unnecessary shutdown of HNB devices is reduced, and usage convenience is enhanced.

[0024] As an implementation method, the first control module 106 is further connected to a voltage input of the first overcurrent protection module and a voltage input of the second overcurrent protection module, respectively, so as to output the first reference voltage and the second reference voltage to the first overcurrent protection module and the second overcurrent protection module, respectively.

[0025] The first control module 106 is connected to the voltage input of the first overcurrent protection module and the voltage input of the second overcurrent protection module, and dynamically adjusts the first reference voltage (Vrefl) and the second reference voltage (Vref2) based on the battery state of charge (State of Charge, SOC) to achieve intelligent and multi-level overcurrent protection. The first control module 106 reads the battery SOC value (which is provided by the BMS) and calculates the first reference voltage (Vrefl) and the second reference voltage (Vref2) based on SOC. If the SOC is greater than a first preset value (e.g., SOC > 90%), Vrefl and Vref2 are appropriately increased to reduce false triggering. If the SOC is less than the second preset value (e.g., SOC < 20%), Vrefl and Vref2 are decreased to trigger protection earlier and prevent over-discharge. The first control module 106 provides Vrefl and Vref2 to the first overcurrent protection module and the second overcurrent protection module, respectively. In the normal state (sensing voltage Vsense < Vref2), the first switch module receives the PWM signal to control the heating power. The second switch module is in a switched-on state, and the first heating circuit is enabled to operate normally. In case of a slight overcurrent (Vrefl ≤ Vsense < Vref2), when the sensing voltage Vsense exceeds Vrefl but is lower than Vref2, the first overcurrent protection module outputs a signal indicating slight overcurrent to the first control module 106. The first control module 106 reduces the duty ratio of the PWM control signal to decrease the heating current until Vsense < Vrefl. The second switch module remains switched-on to avoid complete shutdown and enhance user experience. When detecting the slight overcurrent, the first control module 106 adopts a gradual degradation strategy. The first control module 106 reduces the duty ratio of the PWM control signal by 10%, waits for 50ms to observe whether the current drops. If the sensing voltage remains higher than Vref1, the duty ratio of the PWM control signal is further decreased by 10% until the current drops to a normal level. In case of a severe overcurrent (Vsense ≥ Vref2), when the sensing voltage Vsense exceeds Vref2, the second overcurrent protection module outputs a signal indicating severe overcurrent to the first control module 106. The first control module 106 immediately switches off the second switch module to cut off the first heating circuit, thereby ensuring safety, and triggers an alarm prompt (e.g., LED blinking or buzzer alert).

[0026] This solution can effectively enhance the safety, the endurance, and the intelligentization level of HNB devices, and provide optimal heating effects under different battery states.

[0027] As an implementation method of circuit configuration, as shown in FIG. 4, the first end of the first switch module 101 receives the first voltage, the second end of the first switch module 101 is connected to the first end of the heating element 102, the second end of the heating element 102 is connected to the first end of the second switch module 103, the second end of the second switch module 103 is connected to the first end of the voltage acquisition module 104, and the second end of the voltage acquisition module 104 is grounded.

[0028] In this circuit configuration, the first end of the first switch module 101 receives the first voltage VCC, and its second end is connected to the first end of the heating element 102 and is constituted as a starting part of the first heating circuit. The second end of the heating element 102 is connected to the first end of the second switch module 103 and is constituted as another part of the first heating circuit, thereby allowing current to flow through the heating element 102. The second end of the second switch module 103 is connected to the first end of the voltage acquisition module 104, and the second end of the voltage acquisition module 104 is grounded, the voltage acquisition function is completed and voltage change in the first heating circuit is monitored in real time. The purpose of this circuit configuration is to regulate the current flowing to the heating element 102 through the control of the second switch module 103, and to monitor the voltage in the circuit through the voltage acquisition module 104, thereby achieving effective overcurrent protection and detection of circuit state.

[0029] As an implementation method, as shown in FIG. 4, the first switch module 101 incudes a P-channel metal-oxide-semiconductor (PMOS) transistor Q1 and a first resistor R1. A source electrode of the PMOS transistor Q1 and one end of the first resistor R1 are commonly connected to serve as the first end of the first switch module 101, a gate electrode of the PMOS transistor Q1 and the other end of the first resistor R1 are commonly connected to serve as the control end of the first switch module 101, and a drain electrode of the PMOS transistor Q1 serves as the second end of the first switch module 101.

[0030] The source electrode of the PMOS transistor Q1 is connected to one end of the first resistor R1, and is constituted as a port for current inflow. In this circuit, the source electrode of the PMOS transistor Q1 is connected to a high-level supply voltage VCC. The gate electrode is connected to the other end of the first resistor R1 and serves as the control end of the PMOS transistor Q1. The gate voltage controls switching-on and switching-off states of the PMOS transistor Q1. When the gate voltage is lower than the source voltage, the PMOS transistor Q1 is switched-on so as to allow current to flow therethrough. When the gate voltage approaches the source voltage, the PMOS transistor Q1 is switched-off, thereby preventing current to flow therethrough. The port of the drain electrode of the PMOS transistor Q1 is the port through which current flows out of the PMOS transistor Q1, the current flows towards the heating element 102 through the drain electrode. The first resistor R1 is used to adjust the gate voltage to control the switching-on and switching-off states of the PMOS transistor Q1. When the gate voltage is low, the PMOS transistor Q1 is switched-on, and current flows into the heating element 102 through the drain electrode. When the gate voltage is higher, the PMOS transistor Q1 is switched-off, and thus current stops flowing.

[0031] As an implementation method, as shown in FIG. 4, the second switch module 103 includes a first NMOS transistor Q2 and a first capacitor C1. A source electrode of the first NMOS transistor Q2 and one end of the first capacitor C1 are commonly connected to serve as the first end of the second switch module 103, a gate electrode of the first NMOS transistor Q2 and the other end of the first capacitor C1 are commonly connected to serve as the control end of the second switch module 103, and the drain electrode of the first NMOS transistor Q2 is the second end of the second switch module 103.

[0032] The drain electrode of the first NMOS transistor Q2 receives current inflow. The gate electrode of the first NMOS transistor Q2 and one end of the first capacitor C1 are commonly connected to serve as the control end. The gate voltage controls the switching-on and switching-off of the first NMOS transistor Q2. When the gate voltage is higher than the source voltage, the first NMOS transistor Q2 is switched-on to allow current to flow therethrough. When the gate voltage is lower than the source voltage, the first NMOS transistor Q2 is switched-off, and the current stops flowing. The drain electrode of the first NMOS transistor Q2 is connected to the subsequent part of the first heating circuit. The main function of the first capacitor C1 is to achieve smoothing and transient control of the gate voltage. When the voltage at the control end changes, the first capacitor C1 provides a certain time constant, thereby making the change in the gate voltage smoother and preventing transient problem in the circuit caused by too rapid voltage change. When the voltage at the control end (the gate voltage of the PMOS transistor) is high, the gate voltage of the first NMOS transistor Q2 is higher than the source voltage, the first NMOS transistor Q2 is enabled to be switched-on. Current can flow from the drain electrode to the source electrode and continue to flow to downstream circuit. When the gate voltage of the first NMOS transistor Q2 is lower than the source voltage, the first NMOS transistor Q2 is switched-off, and current cannot flow through the drain electrode, and the current flow in the first heating circuit is cut off.

[0033] As an implementation method, as shown in FIG. 4, the comparison module 111 includes a comparator U1, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, and a seventh resistor R7. One end of the sixth resistor R6 is connected in common with a power terminal of the comparator U1 and receives a second voltage. The other end of the sixth resistor R6 is connected to one end of the seventh resistor R7 and an inverting input of the comparator U1, respectively. The other end of the seventh resistor R7 is grounded. A non-inverting input of the comparator U1 is connected to a first end of the fourth resistor R4 and a first end of the fifth resistor R5, respectively. A second end of the fourth resistor R4 serves as an input of the comparison module 111. A second end of the fifth resistor R5 and the output of the comparator U1 are commonly connected to serve as the output of the comparison module 111.

[0034] As an implementation method, as shown in FIG. 4, the third switch module 112 includes a second NMOS transistor Q3. A drain electrode of the second NMOS transistor Q3 serves as a first end of the third switch module 112, a source electrode of the second NMOS transistor Q3 serves as the second end of the third switch module 112, a gate electrode of the second NMOS transistor Q3 serves as the control end of the third switch module 112, and the other end of the source electrode of the second NMOS transistor Q3 is grounded.

[0035] The comparator U1 serves to compare the voltage signals at two inputs and output a high-level signal or a low-level signal according to a comparison result. The non-inverting input of the comparator U1 is connected to the junction of the fourth resistor R4 and the fifth resistor R5, the two resistors divide the received first voltage together to obtain a voltage V+ for comparison. The inverting input of the comparator U1 is connected to the junction of the sixth resistor R6 and the seventh resistor R7, the second voltage is divided by the sixth resistor R6 and the seventh resistor R7, the inverting input is allowed to receive a reference voltage. When the voltage V+ obtained by dividing the first voltage in the first heating circuit exceeds the reference voltage, the voltage at the inverting input will exceed the voltage at the non-inverting input, thereby causing the comparator U1 to output a high-level signal. Conversely, when the voltage at the inverting input is smaller than the voltage at the non-inverting input, the comparator outputs a low-level signal.

[0036] As an implementation method, the protection circuit further includes a second resistor R2 and a third resistor R3. One end of the second resistor R2 is connected to the control end of the second switch module 103, and the other end of the second resistor R2 and one end of the third resistor R3 are connected in common and then connected to the output of the first control module 106. The other end of the third resistor R3 is connected to the output of the comparison module 111.

[0037] The working principle of the hardware circuit in this technical solution is described as follows: as shown in FIG. 5, when the power supply VDD is powered on, the comparator U1 starts to operate. The voltage VREF at the inverting input of the comparator U1 is the divided voltage of the sixth resistor R6 and the seventh resistor R7, VREF=R7×VDD / (R6+R7). Thus, the magnitude of the voltage VREF can be changed by adjusting the values of the sixth resistor R6 and the seventh resistor R7. When the heating element T1 is not started, no current flows through the first resistor R1, thus, the voltage VSENSE is pulled down to GND by the first resistor R1. At this time, the voltage V+ at the non-inverting input of the comparator U1 is 0V. Since VREF>V+, the output voltage of the comparator U1 is a low-level signal, that is, VOUT is low-level. When it needs to heat the heating element T1, the first control module 106 needs to output a high-level signal EN1 first. When EN1 is high-level and VOUT is low-level, the second NMOS transistor Q3 is switched-off, and the first NMOS transistor Q2 is switched-on. Then, the first control module 106 can turn on the PMOS transistor Q1 by pulling down the PWM1 signal. After the PMOS transistor Q1 is switched-on, current starts to flow through the PMOS transistor Q1, the heating element 102, the first NMOS transistor Q2, and the eighth resistor R8, the current flow direction is shown in FIG. 5. When current starts to flow, the current flowing through the eighth resistor R8 generates a voltage on the eighth resistor R8, at this time, VSENSE=I×R8, I represents the current in the first heating circuit. Since VOUT is GND at this time, V+=VSENSE×R5 / (R4+R5)=I×R8×R5 / (R4+R5), thus, the larger the current I, the higher the voltage at V+. When V+>VREF, the comparator U1 outputs a high-level signal, that is, VOUT is high-level. When VOUT is high, the second NMOS transistor Q3 is switched-on, and the gate electrode of the first NMOS transistor Q2 is pulled down to GND by the second NMOS transistor Q3. Therefore, the first NMOS transistor Q2 is switched-off, after the first NMOS transistor Q2 is switched-off, the current in the first heating circuit stops flowing, and the current I is 0. Thus, VSENSE is pulled down to GND by the eighth resistor R8 again.

[0038] Furthermore, in order to prevent the first NMOS transistor Q2 from frequently switching-on and switching-off after occurrence of an overcurrent event, VOUT needs to continuously output a high level to enable the first NMOS transistor Q2 be maintained in a switched-off state. The premise for VOUT to continuously output a high level is that the voltage at V+ is greater than VREF. Therefore, after the EN1 pin is pulled up, assuming that the voltage at EN1 is VEN1 at this time, the sixth resistor R6 serves to pull up the voltage at V+ to enable the voltage V+ be greater than VREF, that is, V+=VEN1×R4 / (R4+R5+R6), and V+ > VREF. Thus, as long as appropriate resistance parameters are selected, VOUT will continuously output a high level after the overcurrent event occurs, that is, the voltage at VOUT transitions from a low level to a high level after the overcurrent event occurs. Therefore, the first control module 106 can detect an overcurrent event by detecting a rising edge at VOUT. After detecting the overcurrent event, the controller will pull up the PWM1 signal to turn off the PMOS transistor Q1, thereby cutting off the power supply to the heating element 102. In order to eliminate the overcurrent protection event, the controller only needs to pull down the EN1 pin. Therefore, this circuit can achieve hardware-level overcurrent protection, and the actual current detection threshold of the circuit can be adjusted by adjusting the values of the first resistor R1, the fourth resistor R4, the fifth resistor R5, the sixth resistor R6, and the seventh resistor R7.Second embodiment

[0039] As shown in FIG. 6, a heat-not-burn (HNB) device includes a heating element 102, and the protection circuit includes a first switch module 101, a second switch module 103, a temperature acquisition module 108, and an over-temperature protection module 107. The heating element 102, the first switch module 101, and the second switch module 103 are constituted as a second heating circuit. The second switch module 103 and the temperature acquisition module 108 are respectively connected to the over-temperature protection module 107. When the first switch module 101 and the second switch module 103 are in switched-on state, the heating element 102 is in a heating state. The temperature acquisition module 108 outputs an electrical signal to the over-temperature protection module 107 when a temperature of a to-be-tested device changes. When detecting an occurrence of over-temperature of the to-be-tested device based on the electrical signal, the over-temperature protection module 107 outputs a switching-off control signal to the second switch module 103 to cut off the second heating circuit.

[0040] The main function of the first switch module 101 is to control switching-on of the second heating circuit and adjust the current of the second heating circuit. When the first switch module 101 receives a control signal (e.g., a PWM control signal), current is allowed to flow through the heating element 102, thereby initiating the heating process of the heating element 102. The second switch module 103 cooperatively operates with the first switch module 101 to ensure that the second heating circuit is switched-on under normal operating condition. When the temperature is normal, the second switch module 103 and the first switch module 101 maintain the heating state of the heating element 102 together. Once the over-temperature protection module 107 detects an abnormal temperature, the second switch module 103 be will switched-off immediately to cut off the second heating circuit. The temperature acquisition module 108 monitors the temperature of the heating element 102 or the device in real time. When the temperature changes, the temperature acquisition module 108 converts temperature data into an electrical signal and outputs the electrical signal to the over-temperature protection module 107. The over-temperature protection module 107 is the core module of the entire protection circuit, which determines whether the current temperature exceeds the preset safety range according to the electrical signal provided by the temperature acquisition module 108. If an overheating occurring to the HNB device is detected, the over-temperature protection module 107 will output a switching-off control signal to the second switch module 103 to cut off the second heating circuit, thereby preventing the HNB device from being damaged due to overheating or safety problem caused due to overheating.

[0041] The working process of the protection circuit for the HNB device in this embodiment is summarized as follows: when the HNB device is activated, the first switch module 101 and the second switch module 103 are in switched-on state, current is allowed to flow through the heating element 102 to initiate heating. The first switch module 101 adjusts the magnitude of the current flowing through the second heating circuit based on the PWM control signal. 2. The temperature acquisition module 108 monitors the temperature of the to-be-tested device in real-time, converts the temperature into an electrical signal, and sends the converted electrical signal to the over-temperature protection module 107. 3. If the temperature rises to the preset value, the over-temperature protection module 107 determines that the device is in an over-temperature state based on the received electrical signal. 4. When occurrence of over-temperature of the to-be-tested device is detected, the over-temperature protection module 107 controls the second switch module 103 to cut off the second heating circuit immediately through a cutoff signal, thereby stopping heating and ensure the safety of the HNB device.

[0042] It should be noted that when designing a hardware of the over-temperature protection circuit, the various modules can adopt the following structure: The first switch module 101 can be a power semiconductor device, such as a MOSFET, IGBT, or thyristor, these components can regulate the switching on and off of current according to control signals to control start / stop of the heating element 102. The second switch module 103 can be a small relay or MOSFET which is used to cut off the second heating circuit immediately to prevent overheating from occurring. When the overtemperature protection module 107 sends a cutoff signal, this module cuts off the heating current by switching off the circuit, thereby preventing damage to the HNB device due to overheating. The temperature acquisition module 108 generally includes temperature sensors (such as thermistors, thermocouples, etc.), the thermistor (NTC or PTC) can adjust its resistance value according to temperature change, thereby converting it into an electrical signal. This module is used for real-time monitoring of the temperature of the device, converting the temperature change into the electrical signal and transmitting the electrical signal to the overtemperature protection module 107. The overtemperature protection module 107 can be composed of a comparator, microcontroller, or specific protection IC, which monitors temperature with reference to the output electrical signal from the temperature acquisition module 108. This overtemperature protection module 107 analyzes the temperature signal, when the temperature signal exceeds a preset safety threshold value, the overtemperature protection module 107 outputs a cutoff signal to the second switch module 103. The temperature of the to-be-tested device can be the temperature at the battery cell, the heating component or at a certain location inside the device. By monitoring the temperature changes of these key components in real-time, the temperature acquisition module 108 can promptly transmit data to the overtemperature protection module 107, thereby effectively determining whether the sensing temperature has reached an overtemperature threshold and activating the protection mechanism, which ensures that the protection circuit can quickly respond and cut off the second heating circuit when any part of the device overheats, thereby preventing damage to the device or occurrence of safety accident.

[0043] The technical effects of this embodiment are summarized as follows: the protection circuit provided in this technical solution adopts hardware to implement over-temperature protection functions, significantly enhances the reliability of the protection mechanism. Unlike the traditional over-temperature protection relying on software control, this protection circuit achieves faster and more stable over-temperature detection and protection through the coordinated operation of the first switch module 101, the second switch module 103, the temperature acquisition module 108, and the over-temperature protection module 107. When a device temperature rises abnormally, the temperature acquisition module 108 monitors temperature change in real time and transmits a corresponding signal to the over-temperature protection module 107. The over-temperature protection module 107 determines whether over-temperature occurs to the HNB device based on the electrical signal. If the over-temperature occurs, the overtemperature protection module 107 promptly sends a cutoff signal to the second switch module 103 to quickly cut off the second heating circuit, thereby preventing damage or safety accident caused due to overheating of the HNB device. Therefore, this solution can effectively improve the safety and the reliability of HNB device and reduce potential risks caused by over-temperature.

[0044] As an implementation method, as shown in FIG. 7, the over-temperature protection module 107 includes a detection module 113 and a protection switch module 114. An input of the detection module 113 is connected to an output of the temperature acquisition module 108, and an output of the detection module 113 is connected to a control end of the protection switch module 114. A first end of the protection switch module 114 is connected to the control end of the second switch module 103, and a second end of the protection switch module 114 is grounded. The temperature acquisition module 108 outputs a first voltage to the detection module 113. When detecting that the first voltage is greater than a reference voltage, the detection module 113 outputs a switching-on control signal to the protection switch module 114. When the protection switch module 114 is switched-on, the protection switch module 114 enables the control end of the second switch module 103 to be grounded, thereby outputting a switching-off control signal to the second switch module 103.

[0045] The main function of the detection module 113 is to compare the voltage signal from the temperature acquisition module 108 with a preset reference voltage. There exists a functional relationship between the voltage (i.e., the first voltage) output by the temperature acquisition module 108 and the real-time temperature of the HNB device. When the temperature reaches or exceeds the preset safety threshold, the output first voltage will be greater than the reference voltage. When detecting this situation, the detection module 113 will output a control signal to control the protection switch module 114 to initiate a protection operation. When the protection switch module 114 is switched-on in response to the control signal output by the detection module 113, the control end of the second switch module 103 is grounded. Accordingly, a switching-off control signal is sent to the second switch module 103 to cut off the second heating circuit. The working process of this embodiment is described as follows: the temperature acquisition module 108 monitors the temperature of the HNB device in real time and outputs a corresponding voltage signal (i.e., the first voltage) according to temperature change. The detection module 113 receives the first voltage from the temperature acquisition module 108 and compares the first voltage with the preset reference voltage; the reference voltage represents the temperature safety threshold. When the first voltage is greater than the reference voltage, it indicates that the temperature of the HNB device has exceeded the safety range. When the detection module 113 detects that the first voltage is greater than the reference voltage, the detection module 113 outputs a switching-on control signal to activate the protection switch module 114. After the protection switch module 114 is switched-on, the control end of the second switch module 103 is grounded, the second switch module 103 is disabled. Therefore, the second switch module 103 will output a switching-off control signal to cut off the second heating circuit, thereby stopping the operation of the heating element 102.

[0046] The technical effects of the protection circuit for the HNB device in this embodiment are summarized as follows: a quick response to an abnormal temperature of the HNB device can be made and the second heating circuit can be cut off timely through the cooperative operation of the detection module 113 and the protection switch module 114. When the temperature of the HNB device exceeds the safety threshold, the voltage signal output by the temperature acquisition module 108 is detected by the detection module 113 and this voltage signal triggers the protection switch module 114 to be switched-on, thereby achieving cutoff of the second heating circuit. This design ensures that the HNB device can automatically stop heating when overtemperature occurs, thereby effectively preventing faults or safety hazards caused due to overheating. Moreover, the hardware protection mechanism does not rely on a software system, enhances the independence and the stability of the system, and improves the safety and the reliability of the HNB device.

[0047] As an implementation method, as shown in FIG. 8, the hardware over-temperature protection circuit further includes a second control module 109, the second control module 109 is respectively connected to the control end of the first switch module 101, the control end of the second switch module 103, and the output of the detection module 113. The second control module 109 is configured to output a high-level signal to the second switch module 103 to turn on the second switch module 103, output a PWM control signal to the first switch module 101, and receive a switching-on control signal output by the detection module 113.

[0048] The second control module 109 controls the switching-on of the second switch module 103. The second control module 109 outputs a high-level signal to the control end of the second switch module 103 as needed, to enable the second switch module 103 to be switched-on, thereby allowing the second heating circuit to operate normally and ensuring that the heating element 102 heats up within a safe temperature range. The second control module 109 generates a PWM control signal and outputs this PWM control signal to the first switch module 101 to adjust the magnitude of current in the second heating circuit. The change in the PWM control signal can precisely control the power output of the heating element 102, thereby ensuring the stability and the efficiency of the heating process. The second control module 109 receives the switching-on control signal from the detection module 113. When the temperature exceeds the preset safety threshold, the detection module 113 outputs a switching-on control signal, and the second control module 109 responses according to this switching-on control signal. When receiving the switching-on control signal from the detection module 113, the second control module 109 will take measures timely and send an alarm. When overtemperature occurs, the second control module 109 will obtain information indicating that the second heating circuit has been switched-off through the switching-on control signal received by the detection module 113, without the need of switching off the second heating circuit through software.

[0049] The technical effects of the protection circuit for the HNB device in this embodiment are summarized as follows: efficient and precise heating management and over-temperature protection are achieved through the control of the second control module 109. The second control module 109 can not only adjust the heating power through the PWM signal to ensure the stability and the efficiency of the heating process, but also maintain the operating state of the second heating circuit under normal condition. When the temperature exceeds the safety threshold, the second control module 109 receives the switching-on control signal from the detection module 113, responds immediately to trigger an alarm, and automatically cuts off the second heating circuit through the hardware protection mechanism without the need of software intervention for cutoff, thereby improving the reliability and the safety of the system. This solution effectively avoids damage to the HNB device or safety accidents caused by over-temperature, and enhances the stability and the intelligentization level of the HNB device.

[0050] As an implementation method, the second control module 109 is connected to the temperature acquisition module 108. When the second control module 109 detects that the temperature rise rate (dT / dt) is greater than a preset value, the second control module 109 reduces the duty ratio of the PWM control signal or even directly cut off the second heating circuit. By monitoring the temperature change rate, a protection mechanism is triggered in advance to avoid damage to the HNB device due to overheating.

[0051] As an implementation method, the second control module 109 is further connected to the over-temperature protection module 107. The second control module 109 collects battery temperature through the temperature acquisition module 108 and adjusts the reference voltage and the duty ratio of the PWM control signal according to the battery temperature.

[0052] The temperature acquisition module 108 senses the battery temperature, and the second control module 109 controls a heating strategy of the HNB device based on the battery temperature (T_batt). In case of a low temperature (T_batt < 10°C), the PWM duty ratio is appropriately increased (e.g., by +10%) to compensate for power loss at low temperature, and the over-temperature protection threshold is increased (e.g., by +3°C) to prevent cutoff due to false triggering. The standard PWM regulation strategy is maintained without additional restrictions at a normal temperature (10°C ≤ T_batt ≤ 45°C). In case of an overheat warning temperature (45°C < T_batt < 50°C), the PWM duty ratio is reduced (e.g., by -20%) to decrease the heating power, and a pulse heating mode is initiated (intermittent heating to avoid continuous temperature rise), the over-temperature protection threshold is decreased in advance (e.g., by -5°C), in order for earlier intervention in protection. In case of a severe overheating (T_batt ≥ 50°C), the second heating circuit is immediately switched-off to prevent further temperature rise of the battery, waiting for the battery temperature to restore (e.g., the battery temperature drops to a temperature lower than 45°C).

[0053] This implementation method optimizes the heating strategy of the HNB device by dynamically adjusting the reference voltage and the duty ratio of the PWM control signal through real-time detection of battery temperature. In case of low temperature, the duty ratio of the PWM control signal is increased to compensate for power loss, and the overtemperature protection threshold is increased to ensure normal operation of the HNB device. Within the normal temperature range, standard PWM regulation is maintained to ensure the stability of heating. In the overheating warning state, the duty ratio of the PWM control signal is reduced, the pulse heating mode is activated, and the overtemperature protection threshold is lowered in advance to improve overheating response capability. In severe overheating, the second heating circuit is immediately switched off to prevent further temperature rise of the battery, heating is gradually resumed after the temperature restores to the safety range. This solution enhances the safety of the HNB device, optimizes energy efficiency management, reduces false trigger of overtemperature, and improves user experience and reliability of the HNB device.

[0054] As an implementation method of circuit connection, as shown in FIG. 8, the first end of the first switch module 101 receives the second voltage, the second end of the first switch module 101 is connected to the first end of the heating element 102, the second end of the heating element 102 is connected to the first end of the second switch module 103, and the second end of the second switch module 103 is grounded.

[0055] In this circuit connection, the first end of the first switch module 101 receives the second voltage VCC, and the second end of the first switch module 101 is connected to the first end of the heating element 102, and is constituted as a start part of the second heating circuit. The second end of the heating element 102 is connected to the first end of the second switch module 103 and is constituted as another part of the second heating circuit, thereby allowing current to flow through the heating element 102. The second end of the second switch module 103 is grounded. The function of this circuit connection is to regulate the current flowing to the heating element 102 through the control of the first switch module 101, and to cut off the heating element 102 through the second switch module 103 when overtemperature occurs, thereby achieving effective overtemperature protection and detection of circuit state.

[0056] As an implementation method, as shown in FIG. 9, the temperature acquisition module 108 includes a negative temperature coefficient (NTC) thermistor NTC1 and a voltage dividing resistor R16. One end of the NTC thermistor NTC1 receives a third voltage, and the other end of the NTC thermistor NTC1 and one end of the voltage dividing resistor R16 are commonly connected to serve as the output of the temperature acquisition module 108. The other end of the voltage dividing resistor R16 is grounded.

[0057] The resistance value of a NTC thermistor decreases as the temperature rises, and exhibits a predictable resistance variation pattern with temperature changes, making it suitable for precise temperature sensing. In the temperature acquisition module 108, one end of the NTC thermistor NTC1 receives a third voltage, while the other end of the NTC thermistor NTC1 is connected to the voltage dividing resistor R16, thereby forming a temperature-dependent voltage divider network. The voltage variation is inversely proportional to temperature, thereby providing real-time temperature signals for subsequent circuit processing. The voltage dividing resistor R16 and the NTC thermistor NTC1 are constituted as a voltage divider which serves to divide the voltage across the NTC thermistor NTC1 and the third voltage, generating an output voltage proportional to temperature. The other end of the voltage dividing resistor R16 is grounded, thereby providing a stable reference voltage to ensure that the output voltage varies according to the temperature response of the NTC thermistor NTC1.

[0058] The technical effects of the protection circuit for the HNB device in this embodiment are summarized as follows: a high-precision and low-cost temperature monitoring solution is achieved through the cooperation between the NTC thermistor NTC1 and the voltage dividing resistor R16, the system's over-temperature protection function is effectively enhanced, and the safety and the reliability of the HNB device are improved.

[0059] As another implementation method, as shown in FIG. 10, the temperature acquisition module 108 includes a positive temperature coefficient (PTC) thermistor PTC1 and a voltage dividing resistor R16. One end of the voltage dividing resistor R16 receives a third voltage, and the other end of the voltage dividing resistor R16 and one end of the PTC thermistor PTC1 are commonly connected to serve as the output of the temperature acquisition module 108. The other end of the PTC thermistor PTC1 is grounded.

[0060] The resistance value of the PTC thermistor increases as the temperature rises. The PTC thermistor PTC1 exhibits temperature dependence, the resistance value of the PTC thermistor also increases when the temperature rises, conversely, the resistance value of the PTC thermistor decreases when the temperature drops. In the temperature acquisition module 108, one end of the PTC thermistor PTC1 is connected to the voltage dividing resistor R16, and the other end of the PTC thermistor PTC1 is grounded. This circuit configuration enables the resistance change of the PTC thermistor PTC1 to be converted into a measurable voltage signal through the voltage divider network, which reflects real-time temperature change. The function of the voltage dividing resistor R16 is to constitute a voltage divider together with the PTC thermistor PTC1. One end of the voltage dividing resistor receives a third voltage, and the other end of the voltage dividing resistor is connected to one end of the PTC thermistor PTC1, thereby dividing output voltage. Since the resistance value of the PTC thermistor PTC1 varies with temperature change, a voltage signal being proportional to temperature change can be obtained by combining the voltage dividing resistor with the PTC thermistor PTC1.

[0061] The technical effects of the protection circuit for the HNB device in this embodiment are summarized as follows: a high-precision and low-cost temperature monitoring solution is achieved through the cooperation of the PTC thermistor PTC1 and the voltage dividing resistor R16, the over-temperature protection function of the system is effectively enhanced, and the safety and the reliability of the HNB device are improved.

[0062] As an implementation method, as shown in FIG. 9, the detection module 113 includes a comparator U2, a fourteenth resistor R14, and a fifteenth resistor R15. One end of the fifteenth resistor R15 is connected in common with a power terminal of the comparator U2 and receives a third voltage. The other end of the fifteenth resistor R15 is connected to one end of the fourteenth resistor R14 and an inverting input of the comparator U2, respectively. The other end of the fourteenth resistor R14 is grounded, and a non-inverting input of the comparator U2 is connected to the output of the temperature acquisition module 108.

[0063] The comparator U2 compares the input voltage VIN with the reference voltage and outputs a high level or a low level. The non-inverting input is connected to the divided voltage of the fourteenth resistor R14 and the fifteenth resistor R15 to obtain the reference voltage, while the inverting input of the comparator U2 is connected to the output of the temperature acquisition module 108. When the input voltage VIN exceeds the reference voltage, the comparator U2 outputs a high level; otherwise, the comparator U2 outputs a low level.

[0064] As an implementation method, as shown in FIG. 9, the protection switch module 114 includes a fourth MOSFET Q4. A drain electrode of the fourth MOSFET Q4 is the first end of the protection switch module 114, a source electrode of the fourth MOSFET Q4 is the second end of the protection switch module 114, a gate electrode of the fourth MOSFET Q4 is the control end of the protection switch module 114, and the other end of the source of the fourth MOSFET Q4 is grounded.

[0065] The working principle of the hardware of this solution is described as follows: when a power supply VDD is powered on, the comparator U2 starts to operate. The voltage VREF at the inverting input of comparator U2 is the divided voltage VREF of the fourteenth resistor R14 and the fifteenth resistor R15, VREF=R14×VDD / (R14+R15). Therefore, the magnitude of voltage VREF may be changed by adjusting the resistance values of the fourteenth resistor R14 and the fifteenth resistor R15. The voltage VIN at the non-inverting input of comparator U2 is the divided voltage of the thermistor NTC1 and the voltage dividing resistor R16, VIN=R16×VDD / (RNTC1+R16), and RNTC1 is the resistance of the thermistor NTC1. The magnitude of the first voltage VIN changes with temperature, since the thermistor NTC1 has a negative temperature coefficient. Therefore, the higher the temperature, the lower the resistance value of the thermistor NTC1. When the value of the voltage dividing resistor R16 is fixed, the value of the first voltage VIN increases with the increasing of temperature. The thermistor NTC1 can be a negative temperature coefficient thermistor fixed at a certain position inside the battery cell, the heating component, or the HNB device. When the temperature at the thermistor NTC1 is below a preset temperature threshold, VREF>VIN. Therefore, the comparator U2 outputs a low level signal, that is, VOUT is at a low level. When the heating component needs to be heated, the second control module needs to output a high level signal EN1 first. When EN1 is at a high level and VOUT is at a low level, the fourth MOSFET Q4 is switched-off and the second MOSFET Q2 is switched-on. Then, the second control module can turn on the first MOSFET Q1 by pulling down the PWM1 signal. After the first MOSFET Q1 is switched-on, current flows through the first MOSFET Q1, the heating element 102, the second MOSFET Q2, and the second heating circuit, the heating process is started. When the temperature is normal and the operation is not out of control, the temperature of the thermistor NTC1 will always be kept below the preset temperature threshold, and the overtemperature protection circuit will not actuate. When the temperature becomes out of control, the temperature at the thermistor NTC1 will exceed the preset temperature threshold, and VIN>VREF. The comparator U2 outputs VOUT as a high level signal. At this time, the fourth MOSFET Q4 will be switched-on. After the fourth MOSFET Q4 is switched-on, the Gate electrode of the second MOSFET Q2 is pulled down to GND. Therefore, the second MOSFET Q2 will be switched-off, current stops flowing, and the heating process is stopped. The voltage at VOUT will be transitioned from low level to high level after the overtemperature event occurs. The second control module can also detect the overtemperature event by detecting this transition signal or high level signal and inform the user of the overtemperature. The comparator U2 outputs VOUT at a low level only when the temperature drops below the preset temperature, that is, VIN<VREF. At this time, the second control module can detect this low level signal to resolve the overtemperature event.

[0066] As shown in FIG. 10, the difference between FIG.10 and FIG. 9 lies in that the NTC thermistor is replaced with a PTC thermistor, and the position of the voltage dividing resistor is changed. The characteristic of the PTC thermistor is that the higher the temperature, the greater the value of the resistance of the PTC thermistor. VIN=PTC1×VDD / (PTC1+R16), which means that the higher the temperature, the greater the magnitude of VIN. Therefore, this circuit can also be utilized to achieve the same effect as the circuit shown in FIG. 4, which will not be repeatedly described here.Third Embodiment

[0067] A HNB device is provided in the third embodiment, the HNB device includes the protection circuit provided in the first embodiment or the second embodiment.

Claims

1. A protection circuit for a HNB device comprising a heating element, characterized in that, the protection circuit comprises a first switch module and a second switch module; the protection circuit comprises a voltage acquisition module and an overcurrent protection module; the heating element, the first switch module, the second switch module, and the voltage acquisition module are constituted as a first heating circuit, and the second switch module and the voltage acquisition module are connected to the overcurrent protection module, respectively; when the second switch module is in a switched-on state, the first switch module receives a PWM control signal and enables the first heating circuit to perform heating, and adjusts a magnitude of a current flowing through the first heating circuit according to the PWM control signal, when the overcurrent protection module detects an occurrence of overcurrent in the first heating circuit based on a sensing voltage output by the voltage acquisition module, the overcurrent protection module is configured to output a switching-off control signal to the second switch module to cut off the first heating circuit; or alternatively, the protection circuit further comprises a temperature acquisition module and an over-temperature protection module; the heating element, the first switch module, and the second switch module are constituted as a second heating circuit, the second switch module and the temperature acquisition module are connected to the over-temperature protection module, respectively; when the first switch module and the second switch module are in a switched-on state, the heating element is in a heating state, the temperature acquisition module outputs an electrical signal to the over-temperature protection module when a temperature of a to-be-tested device changes, the over-temperature protection module outputs the switching-off control signal to the second switch module to cut off the second heating circuit when detecting an occurrence of over-temperature in the to-be-tested device based on the electrical signal.

2. The protection circuit according to claim 1, wherein the overcurrent protection module comprises a comparison module and a third switch module, an input of the comparison module is connected to an output of the voltage acquisition module, an output of the comparison module is connected to a control end of the third switch module, a first end of the third switch module is connected to a control end of the second switch module, and a second end of the third switch module is grounded; the comparison module outputs a switching-on control signal to the third switch module when detecting that the sensing voltage is greater than a reference voltage, the third switch module enables the control end of the second switch module to be grounded when it is switched-on, thereby outputting the switching-off control signal to the second switch module.

3. The protection circuit according to claim 2, further comprising a first control module which is connected to a control end of the first switch module, the control end of the second switch module and the output of the comparison module; the first control module is configured to output a high-level signal to the second switch module to make the second switch module switched-on, output a PWM control signal to the first switch module, and receive the switching-on control signal output by the comparison module.

4. The protection circuit according to claim 2, wherein the control module is connected to a voltage input of the comparison module to output the reference voltage to the comparison module.

5. The protection circuit according to claim 3, wherein the overcurrent protection module further comprises a first overcurrent protection module and a second overcurrent protection module, two inputs of the first overcurrent protection module receive the sensing voltage and a first reference voltage respectively, and an output of the first overcurrent protection module is connected to the first control module and the second switch module, two inputs of the second overcurrent protection module receive the sensing voltage and a second reference voltage respectively, and an output of the second overcurrent protection module is connected to the first control module and the second switch module, wherein the first reference voltage is greater than the second reference voltage.

6. The protection circuit according to claim 5, wherein the control module is further connected to a voltage input of the first overcurrent protection module and a voltage input of the second overcurrent protection module respectively so as to output the first reference voltage and the second reference voltage to the first overcurrent protection module and the second overcurrent protection module, respectively.

7. The protection circuit according to claim 3, wherein a first end of the first switch module receives a first voltage, a second end of the first switch module is connected to a first end of the heating element, a second end of the heating element is connected to a first end of the second switch module, a second end of the second switch module is connected to a first end of the voltage acquisition module, and a second end of the voltage acquisition module is grounded.

8. The protection circuit according to claim 7, wherein the first switch module comprises a PMOS transistor and a first resistor, a source electrode of the PMOS transistor and one end of the first resistor are commonly connected to serve as the first end of the first switch module, a gate electrode of the PMOS transistor and an other end of the first resistor are commonly connected to serve as the control end of the first switch module, and a drain electrode of the PMOS transistor is the second end of the first switch module; the second switch module comprises a first NMOS transistor and a first capacitor, a source electrode of the first NMOS transistor and one end of the first capacitor are commonly connected to serve as the first end of the second switch module, a gate electrode of the first NMOS transistor and an other end of the first capacitor are commonly connected to serve as the control end of the second switch module, and a drain electrode of the first NMOS transistor serves as the second end of the second switch module; the comparison module comprises a comparator, a fourth resistor, a fifth resistor, a sixth resistor, and a seventh resistor, one end of the sixth resistor is connected in common with a power terminal of the comparator and receives a second voltage, an other end of the sixth resistor is connected to one end of the seventh resistor and an inverting input of the comparator respectively, an other end of the seventh resistor is grounded, an non-inverting input of the comparator is connected to a first end of the fourth resistor and a first end of the fifth resistor respectively, a second end of the fourth resistor serves as an input of the comparison module, and a second end of the fifth resistor and an output of the comparator are commonly connected to serve as the output of the comparison module.

9. The protection circuit according to claim 1, wherein the over-temperature protection module comprises a detection module and a protection switch module, an input of the detection module is connected to an output of the temperature acquisition module, an output of the detection module is connected to a control end of the protection switch module, a first end of the protection switch module is connected to a control end of the second switch module, and the second end of the protection switch module is grounded; the temperature acquisition module outputs a first voltage to the detection module, the detection module output a switching-on control signal to the protection switch module when detecting that the first voltage is greater than a reference voltage, the protection switch module causes the control end of the second switch module to be grounded when it is switched-on, thereby outputting the switching-off control signal to the second switch module.

10. The protection circuit according to claim 9, wherein the over-temperature protection circuit further comprises a second control module which is connected to a control end of the first switch module, the control end of the second switch module, and the output of the detection module respectively; the second control module is configured to output a high-level signal to the second switch module to enable the second switch module be switched-on, output a PWM control signal to the first switch module, and receive the switching-on control signal output by the detection module.

11. The protection circuit according to claim 9, wherein the temperature acquisition module comprises a NTC thermistor and a voltage dividing resistor, one end of the NTC thermistor receives a third voltage, an other end of the NTC thermistor and one end of the voltage dividing resistor are commonly connected to serve as the output of the temperature acquisition module, and an other end of the voltage dividing resistor is grounded; or alternatively, the temperature acquisition module comprises a PTC thermistor and a voltage dividing resistor, wherein one end of the voltage dividing resistor receives the third voltage, an other end of the voltage dividing resistor and one end of the PTC thermistor are commonly connected to serve as the output of the temperature acquisition module, and an other end of the PTC thermistor is grounded.

12. The protection circuit according to claim 9, wherein the second control module is connected to the temperature acquisition module, the second control module adjusts a duty ratio of the PWM control signal when detecting that a temperature rise rate is greater than a preset value.

13. The protection circuit according to claim 10, wherein the second control module is further connected to the over-temperature protection module, and the second control module acquires a battery temperature through the temperature acquisition module and adjusts the reference voltage and a duty ratio of the PWM control signal according to the battery temperature.

14. The protection circuit according to claim 9, wherein a first end of the first switch module receives a second voltage, a second end of the first switch module is connected to a first end of the heating element, a second end of the heating element is connected to a first end of the second switch module, and a second end of the second switch module is grounded; the detection module comprises a comparator, a fourteenth resistor, and a fifteenth resistor, wherein one end of the fifteenth resistor is connected in common with a power terminal of the comparator and receive a third voltage, an other end of the fifteenth resistor is connected to one end of the fourteenth resistor and an inverting input of the comparator respectively, an other end of the fourteenth resistor is grounded, and an non-inverting input of the comparator is connected to the output of the temperature acquisition module.

15. A HNB device, characterized by comprising the protection circuit according to any one of claims 1 to 14.

Images