Heating circuit, heating control method, and aerosol generation device

Abstract

The application discloses a heating circuit for an aerosol generating device, comprising an electronic switch driving circuit, one end of which is connected with an external control source to receive a PWM signal and shape; the other end is connected with the gate of the electronic switch, and according to the duty cycle of the shaped PWM signal being a non-zero value or a zero value, the heating circuit is controlled to be in a working state or a non-working state; a charge release circuit, one end of which is connected with the other end of the electronic switch driving circuit and the gate, and the other end is grounded; an oscillation circuit, one end of which is connected with a power supply, and the other end is connected with a drain, and when the heating circuit is in the working state, the oscillation circuit can generate an induced current; a high-voltage suppression circuit, one end of which is connected with the drain and the other end of the oscillation circuit, and the other end is grounded. The heating circuit provided by the application avoids the formation of transient high voltage at both ends of the electronic switch when turned on or off, damages or even breaks the electronic switch element, and ensures the normal working of the heating circuit. The application provides a heating control method and an aerosol generating device.

Description

Technical Field

[0001] This invention relates to the field of novel tobacco products, specifically to a heating circuit, a heating control method, and an aerosol generating device. Background Technology

[0002] Traditional tobacco harms users' health, and new aerosol generating devices, as alternatives to traditional tobacco, have seen rapid development in recent years. Common aerosol generating devices can be broadly categorized according to the form of the aerosol-generating material, such as e-cigarettes and heated cigarettes. E-cigarettes use liquid materials to generate aerosols, while heated cigarettes use solid materials, i.e., solid aerosol-forming matrices, such as tobacco sheets, tobacco particles, shredded tobacco, and reconstituted tobacco.

[0003] Existing aerosol generating devices primarily employ two heating methods: resistance heating and electromagnetic heating. Resistance heating aerosol generating devices utilize the Joule effect of electric current to convert electrical energy into heat energy. This heat energy is generated by a heating element and transferred to the object being heated through radiation, convection, and conduction. Electromagnetic heating aerosol generating devices utilize a high-frequency alternating voltage applied to an electromagnetic heating coil wound around the surface of the object to be heated, thereby generating a magnetic field. This magnetic field acts on the surface of the object, inducing eddy currents within it, which in turn generate heat.

[0004] Among the common electromagnetic drive methods, there are single-transistor drive, half-bridge drive, full-bridge drive, and E-type power amplifier drive. Existing single-transistor drive circuits are relatively simple. When the electronic switch is on, current rapidly charges the coil; when the electronic switch is off, the coil current charges the resonant capacitor, generating a very high reverse voltage. When the reverse voltage exceeds the withstand voltage of the electronic switch, the electronic switch will instantly break down (commonly known as a "breakdown"). Single-transistor circuits also have a significant and inherent flaw: at low power levels, they affect the electronic switch's operating state, causing severe overheating, shortening its lifespan, and even causing it to break down (breakdown).

[0005] Therefore, when the existing single-tube drive circuit is turned on or off, a sudden high voltage will be formed across the electronic switch due to the rapid change in current. When the voltage value of this high voltage is greater than the withstand voltage of the electronic switch, the electronic switch will be damaged or even broken down, resulting in the electromagnetic heating circuit failing to work properly. Summary of the Invention

[0006] The purpose of this invention is to solve the problem that when the existing single-tube drive circuit is turned on or off, a sudden high voltage is formed across the electronic switch due to the rapid change in current. When the voltage value of this high voltage exceeds the withstand voltage of the electronic switch, the electronic switch will be damaged or even broken down, thus causing the electromagnetic heating circuit to malfunction.

[0007] Firstly, the heating circuit provided by the present invention avoids the problem of electronic switches being damaged or even broken down when a single-tube drive circuit is turned on or off, thus ensuring the normal operation of the electromagnetic heating circuit.

[0008] To address the aforementioned technical problems, embodiments of the present invention disclose a heating circuit for an aerosol generating device, comprising: an electronic switch driving circuit, one end of which is connected to an external control source for receiving and shaping a PWM signal output from the external control source; and an electronic switch, one end of which is connected to the other end of the electronic switch driving circuit for controlling the heating circuit to be in an operating state or a non-operating state based on whether the duty cycle of the shaped PWM signal output by the electronic drive switch circuit is non-zero or zero. Specifically, when the duty cycle of the PWM signal is zero, the electronic switch is off, controlling the heating circuit to be in a non-operating state; when the duty cycle of the PWM signal is non-zero, the electronic switch is intermittently on, controlling the heating circuit to be in an operating state. The circuit consists of a charge release circuit, one end of which is connected to the other end of the electronic switch drive circuit and one end of the electronic switch, with the other end grounded. An oscillation circuit is connected to a power supply at one end and to the other end of the electronic switch at the other end. When the heating circuit is in operation, the oscillation circuit generates an induced current, causing the heating element in the aerosol generating device to heat up. A high-voltage suppression circuit is also included, with one end connected to the other end of the electronic switch and the other end of the oscillation circuit, with the other end grounded.

[0009] Using the above technical solution, the heating circuit provided by the present invention is equipped with an electronic switch driving circuit for receiving the PWM signal output by an external control source and shaping the PWM signal. Specifically, the PWM signal shaping is as follows: first, the low-voltage PWM signal is converted into a high-voltage PWM signal and the high-voltage PWM signal is output to the gate of the electronic switch to reduce the on-resistance of the electronic switch; second, the PWM signal (square wave signal) is shaped by shortening the falling edge time of the PWM signal to reduce the loss of the electronic switch.

[0010] A charge discharge circuit is installed on the gate of the electronic switch. When the electronic switch is turned off, the gate of the electronic switch is discharged to ground to prevent charge from accumulating on the gate and avoid malfunction of the electronic switch.

[0011] A high-voltage suppression circuit is installed at the drain of the electronic switch. When the electronic switch is turned on, if the voltage across the electronic switch is lower than the voltage of the high-voltage suppression circuit, the high-voltage suppression circuit is equivalent to an open circuit and will not affect the normal operation of the oscillation circuit. When the electronic switch is turned on, if the voltage across the electronic switch is higher than the voltage of the high-voltage suppression circuit, the high-voltage suppression circuit forms an open circuit to ground, allowing the high-voltage energy to be released to ground, thus preventing the electronic switch from being damaged or broken down.

[0012] Through the above circuit improvements, the heating circuit avoids the formation of instantaneous high voltage across the electronic switch when the electromagnetic heating circuit is turned on or off, which could damage or even break down the electronic switch, thus ensuring that the electromagnetic heating circuit can work normally.

[0013] According to another specific embodiment of the present invention, the electronic switch driving circuit includes: a first signal shaping circuit, one end of which is connected to an external control source, for receiving a PWM signal output by the external control source, and converting the first-level PWM signal output by the external control source into a second-level PWM signal, wherein the first level is lower than the second level.

[0014] According to another specific embodiment of the present invention, the first signal shaping circuit includes a level conversion chip and a first resistor connected in series, wherein the first pin of the level conversion chip is connected to one end of the first resistor, and the other end of the first resistor is connected to the fifth pin of the level conversion chip; the second pin of the level conversion chip is grounded; the third pin of the level conversion chip is connected to an external control source for receiving a first-level PWM signal; and the fourth pin of the level conversion chip is connected to the gate of an electronic switch for controlling the on and off states of the electronic switch.

[0015] According to another specific embodiment of the present invention, the heating circuit includes: a second signal shaping circuit, one end of which is connected in series with a first signal shaping circuit, and the other end of which is connected in series with the gate of an electronic switch, for shaping a second-level PWM signal.

[0016] According to another specific embodiment of the present invention, the second signal shaping circuit includes a second resistor and a first diode connected in parallel. The fourth pin of the level conversion chip is connected to one end of the second resistor and the first diode, and the other end of the second resistor and the first diode is connected to the gate of the electronic switch for controlling the conduction and cutoff of the electronic switch.

[0017] According to another specific embodiment of the present invention, the first signal shaping circuit further includes a first capacitor and a second capacitor. The first and second pins of the level conversion chip are connected in parallel with the first capacitor, that is, the first capacitor is connected in parallel with the first and second pins of the level conversion chip. The sixth pin of the level conversion chip is grounded through the second capacitor.

[0018] According to another specific embodiment of the present invention, the first signal shaping circuit further includes a third resistor, and the third pin of the level conversion chip is grounded through the third resistor.

[0019] According to another specific embodiment of the present invention, the charge release circuit includes a fourth resistor and / or a second diode connected in parallel with the fourth resistor.

[0020] According to another specific embodiment of the present invention, the high voltage suppression circuit includes a third diode, one end of which is connected to the drain of the electronic switch and the other end of the oscillation circuit, and the other end of the third diode is grounded.

[0021] According to another specific embodiment of the present invention, the high voltage suppression circuit includes a third capacitor and a fifth resistor, which are connected in parallel. One end of the third capacitor and the fifth resistor is connected to the other end of the third diode, and the other end of the third capacitor and the fifth resistor is grounded.

[0022] According to another specific embodiment of the present invention, the heating circuit further includes a third capacitor and a fourth capacitor, one end of the third capacitor and the fourth capacitor being connected to one end of the oscillation circuit, and the other end of the third capacitor and the fourth capacitor being grounded.

[0023] According to another specific embodiment of the present invention, the frequency range of the PWM signal is 10kHz to 300kHz. In a second aspect, embodiments of the present invention disclose a heating control method for a heating circuit as described above. The heating control method includes: determining an initial value for the duty cycle of a first-level PWM signal; controlling the duty cycle of the first-level PWM signal output from an external control source to gradually increase from the initial value, wherein the first-level PWM signal is at a high level to turn on the electronic switch and put the heating circuit in a working state; until the duty cycle of the first-level PWM signal rises to a preset threshold; wherein the preset threshold is higher than the initial value; starting a first timer to count until the first timer overflows; controlling the duty cycle of the first-level PWM signal to gradually decrease from the preset threshold, wherein the first-level PWM signal is at a low level to turn off the electronic switch and put the heating circuit in a non-working state; until the duty cycle of the first-level PWM signal drops to the initial value; starting a second timer to count until the second timer overflows; repeating the above steps.

[0024] By employing the above technical solution, the duty cycle of the PWM signal is smoothly controlled, gradually increasing from its initial value to a preset threshold or gradually decreasing from the preset threshold to its initial value. This reduces voltage surges in the heating circuit and prevents damage to the electronic switching components. Intermittent control of the PWM signal, specifically setting its duty cycle to a non-zero value (not 100% in this invention), allows for intermittent heating. After the duty cycle of the first-level PWM signal decreases from the preset threshold to its initial value, a second timer begins counting until it overflows, causing the oscillation circuit to discharge attenuated and reducing charge accumulation. Through this heating control method, the heating circuit avoids the formation of instantaneous high voltage across the switch during single-tube drive circuit operation, which could damage or even break down the electronic switching components, ensuring the normal operation of the electromagnetic heating circuit.

[0025] According to another specific embodiment of the present invention, after determining the initial value of the duty cycle of the first-level PWM signal output by the external control source, the heating control method further includes: delaying the initial value for a first preset time.

[0026] According to another specific embodiment of the present invention, in the case of the first timer overflowing, after reducing the duty cycle by a second preset step size, the heating control method further includes: delaying for a second preset time at a preset threshold.

[0027] Thirdly, the present invention provides an aerosol generating apparatus, comprising: a heating circuit as described in any embodiment of the first aspect above; and a heating element, wherein, when the heating circuit is in operation, the oscillating circuit is capable of generating an induced current to cause the heating element to heat up.

[0028] By adopting the above technical solution, the aerosol generating device can heat the heating element by means of electromagnetic heating through the heating circuit. The heating circuit avoids the instantaneous high voltage that would form at both ends of the switch when the single tube drive circuit is working, which could damage or even break down the electronic switch element, thus ensuring the normal operation of the electromagnetic heating circuit. Attached Figure Description

[0029] Figure 1 A block diagram of a heating circuit according to an embodiment of the present invention is shown;

[0030] Figure 2 A circuit diagram of a heating circuit according to an embodiment of the present invention is shown;

[0031] Figure 3 A flowchart of a heating control method according to an embodiment of the present invention is shown. Detailed Implementation

[0032] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Although the description of the present invention is presented in conjunction with preferred embodiments, this does not mean that the features of the invention are limited to this embodiment. On the contrary, the purpose of describing the invention in conjunction with embodiments is to cover other options or modifications that may be derived based on the claims of the present invention. To provide a deep understanding of the invention, many specific details will be included in the following description. The invention may also be implemented without using these details. Furthermore, to avoid confusion or obscuring the focus of the invention, some specific details will be omitted in the description. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0033] It should be noted that in this specification, similar reference numerals and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0034] The terms “first”, “second”, etc., are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0035] In the description of this embodiment, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set up," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this embodiment based on the specific circumstances.

[0036] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0037] Firstly, reference Figure 1 and Figure 2 The present invention provides a heating circuit 1 for an aerosol generating device. The heating circuit 1 provided by the present invention is an electromagnetic heating circuit, specifically a single-tube drive circuit.

[0038] refer to Figure 1 and Figure 2 The heating circuit 1 includes an electronic switch drive circuit 11 and an electronic switch M1 (i.e., Figure 1 The circuit shown includes an electronic switch 12 (hereinafter referred to as electronic switch M1), a charge release circuit 13, an oscillation circuit 14, and a high voltage suppression circuit 15.

[0039] One end of the electronic switch drive circuit 11 is connected to an external control source to receive the PWM signal output by the external control source and to shape the PWM signal.

[0040] One end (gate G) of the electronic switch M1 is connected to the other end of the electronic switch drive circuit 11, and is used to control the heating circuit 1 to be in an operating state or a non-operating state according to the duty cycle of the shaped PWM signal output by the electronic drive switch circuit. Specifically, when the duty cycle of the PWM signal is zero, the electronic switch is off, and the heating circuit is controlled to be in a non-operating state; when the duty cycle of the PWM signal is non-zero (and the duty cycle is not 100%), the heating circuit is controlled to be in an operating state, and the electronic switch is intermittently turned on.

[0041] One end of the charge release circuit 13 is connected to the other end of the electronic switch drive circuit 11 and one end (gate G) of the electronic switch M1, and the other end of the charge release circuit 13 is grounded.

[0042] One end of the oscillation circuit 14 is connected to the power supply B+, and the other end of the oscillation circuit 14 is connected to the other end (drain D) of the electronic switch M1. When the heating circuit 1 is in operation, the oscillation circuit 14 can generate an induced current, which causes the heating element in the aerosol generating device to heat up.

[0043] The high voltage suppression circuit 15 has one end connected to the other end (drain D) of the electronic switch M1 and the other end of the oscillation circuit 14, and the other end of the high voltage suppression circuit 15 is grounded.

[0044] Using the above technical solution, refer to Figure 2 The heating circuit 1 provided by the present invention is equipped with an electronic switch driving circuit 11 for receiving PWM signals output from an external control source and shaping the PWM signals. Specifically, the PWM signal shaping includes:

[0045] First, the low-voltage PWM signal is converted into a high-voltage PWM signal, and then the high-voltage PWM signal is output to the gate G of the electronic switch M1 to reduce the on-resistance of the electronic switch M1. In this embodiment, reference... Figure 2 It converts the low-voltage PWM signal into a high-voltage PWM signal, that is, it converts the 3V PWM signal into a 5.5V PWM signal, in order to reduce the on-resistance of the electronic switch M1.

[0046] Secondly, by increasing the speed of the falling edge of the PWM signal, the falling edge time of the PWM signal is shortened, thus shaping the PWM signal (square wave signal) and reducing the losses of electronic switch M1. The edge rate of a signal refers to the response time of a signal edge change, usually measured by the rise time and fall time. Shortening the falling edge time of the PWM signal is equivalent to increasing the falling edge speed.

[0047] The electronic switch drive circuit 11 shapes the PWM signal, improving the conversion efficiency of the electric field and magnetic field of the sensor in the oscillation circuit 14.

[0048] Using the above technical solution, the heating circuit 1 provided by the present invention provides a charge release circuit 13 in the gate G of the electronic switch M1. When the electronic switch M1 is turned off, the gate G of the electronic switch M1 is discharged to the ground to prevent charge from accumulating in the gate G and avoid the electronic switch M1 from malfunctioning.

[0049] For example, refer to Figure 2 In this embodiment, a MOSFET is used as the electronic switch. Since the MOSFET is a voltage-driven element, it is sensitive to voltage. On one hand, if the gate G is floating (e.g., the second resistor R20 is disconnected for some reason), external interference signals charge the GS junction capacitance. Even a small amount of charge can be stored there for a long time, causing the MOSFET to malfunction, i.e., turn on, or even damage the MOSFET. On the other hand, when the MOSFET is off, the resistance between GS is very high, and the capacitance between GS is very small. The voltage across the capacitor equals the charge / capacitance (i.e., U = Q / C, where U is the voltage across the capacitor, Q is the charge, and C is the capacitance). According to this formula, even a small amount of static electricity can generate a very high voltage between GS. If this small amount of static electricity is not discharged in time, the high voltage across GS may cause the MOSFET to malfunction, or even break down the GS terminals. Therefore, a charge release circuit 13 needs to be set at the gate G of the electronic switch M1 to release the charge and protect the MOSFET from damage.

[0050] In some other possible embodiments of the present invention, the electronic switch may be an IGBT or a Darlington transistor, and the present invention does not limit it to this.

[0051] Using the above technical solution, refer to Figure 2 The heating circuit 1 provided by this invention includes a high-voltage suppression circuit 15 at the drain D of the electronic switch M1. When the electronic switch M1 is turned on, if the voltage across the electronic switch M1 is lower than the voltage of the high-voltage suppression circuit 15, the high-voltage suppression circuit 15 is effectively open-circuited and will not affect the normal operation of the oscillation circuit 14. When the electronic switch M1 is turned on, if the voltage across the electronic switch M1 is higher than the voltage of the high-voltage suppression circuit 15, the high-voltage suppression circuit 15 forms an open-circuit loop to ground, allowing the high-voltage energy to be released to ground and preventing damage or breakdown of the electronic switch M1.

[0052] Through the aforementioned circuit improvements, namely the inclusion of an electronic switch drive circuit 11, an electronic switch, a charge release circuit 13, an oscillation circuit 14, and a high-voltage suppression circuit 15 in the heating circuit 1, the instantaneous high voltage across the electronic switch M1 is prevented from forming when the electromagnetic heating circuit 1 is turned on or off, thus avoiding damage or even breakdown of the electronic switch M1 and ensuring the normal operation of the electromagnetic heating circuit 1. Simultaneously, the electronic switch drive circuit 11 shapes the PWM signal, improving the conversion efficiency of the electric and magnetic fields of the sensor in the oscillation circuit 14.

[0053] In this embodiment, the oscillation circuit 14 includes an inductor L2 connected in parallel and resonant capacitors C9, C10, and C11. When energized, the inductor L2 generates an induced current in the heating element to achieve heating. In some other possible embodiments, the oscillation circuit 14 includes an inductor and a resonant capacitor connected in parallel, such as inductor L2 and resonant capacitor C9. Users can choose the size or number of resonant capacitors as needed, and this invention does not limit this.

[0054] In some possible embodiments provided by the present invention, the electronic switch driving circuit 11 includes a first signal shaping circuit. Specifically, as follows:

[0055] One end of the first signal shaping circuit is connected to an external control source to receive the PWM signal output by the external control source and to convert the first-level PWM signal into a second-level PWM signal. The first level is lower than the second level.

[0056] For example, refer to Figure 2 The first signal shaping circuit receives a 3V PWM signal (first level PWM signal) output from an external control source, performs level conversion on the 3V PWM signal (i.e., shapes the first level PWM signal), and outputs a 5.5V PWM signal (second level PWM signal), thereby reducing the on-resistance of the electronic switch M1, reducing the loss during current conduction, and enabling the oscillation circuit 14 to maintain a high heating efficiency.

[0057] In some possible embodiments provided by the present invention, the electronic switch driving circuit 11 includes a second signal shaping circuit. One end of the second signal shaping circuit is connected in series with the first signal shaping circuit, and the other end of the second signal shaping circuit is connected in series with the gate G of the electronic switch M1, for shaping a second-level PWM signal.

[0058] One end of the second signal shaping circuit is connected in series with the first signal shaping circuit. It can receive the 5.5V PWM signal (second level PWM signal) output by the first signal shaping circuit and shape the 5.5V PWM signal by increasing the speed of the falling edge of the 5.5V PWM signal and shortening the falling edge time of the 5.5V PWM signal, thereby reducing the loss of electronic switch M1 and keeping the oscillation circuit 14 at a high heating efficiency.

[0059] In some other possible embodiments provided by the present invention, the electronic switch driving circuit 11 includes a first signal shaping circuit and a second signal shaping circuit. The first signal shaping circuit and the second signal shaping circuit realize the shaping of the 3V PWM signal (the first level PWM signal), thereby improving the conversion efficiency of the electric field and magnetic field of the sensor in the oscillation circuit 14.

[0060] In some possible embodiments provided by the present invention, the first signal shaping circuit includes a level conversion chip U5 and a first resistor R18 connected in series. The first pin of the level conversion chip U5 is connected to one end of the first resistor R18, and the other end of the first resistor R18 is connected to the fifth pin of the level conversion chip U5. The second pin of the level conversion chip U5 is grounded; the third pin of the level conversion chip U5 is connected to an external control source to receive a first-level PWM signal; and the fourth pin of the level conversion chip U5 is connected to the gate G of the electronic switch M1 to control the on and off states of the electronic switch M1. The first signal shaping circuit (the level conversion chip U5 and the first resistor R18 connected in series) converts the first-level PWM signal into a second-level PWM signal.

[0061] For example, refer to Figure 2 The third pin of the level conversion chip U5 is connected to an external control source, receiving a 3V PWM signal (the first level PWM signal) output from the external control source. At this time, the voltage of VCCA is 3V. The voltage of VCCA is pulled up to 5.5V by the first resistor R18 (i.e., the pull-up resistor), and then to the fifth pin of the first level conversion chip U5 (the fifth pin is DIR, which controls the direction of data flow; a high DIR level indicates that data is input from A and output from B), thus the voltage of VCCB is 5.5V. The fourth pin of the level conversion chip U5 is connected to the gate G of the electronic switch M1, so that the duty cycle of the PWM signal output by the level conversion chip U5 controls the heating circuit to be in an operating or non-operating state. Specifically, when the duty cycle of the PWM signal is zero, the electronic switch is off, and the heating circuit is in a non-operating state; when the duty cycle of the PWM signal is non-zero, the heating circuit is in an operating state, and the electronic switch is intermittently turned on.

[0062] In some possible embodiments provided by the present invention, the second signal shaping circuit includes a second resistor R20 and a first diode D9 connected in parallel. The fourth pin of the level conversion chip U5 is connected to one end of the second resistor R20 and the first diode D9. The other end of the second resistor R20 and the first diode D9 is connected to the gate G of the electronic switch M1, used to control the conduction and cutoff of the electronic switch M1. That is, the low-level signal or high-level signal output by the level conversion chip U5 controls the electronic switch M1 to be cut off or turned on, so that the heating circuit is in a working state or a non-working state.

[0063] In some possible embodiments provided by the present invention, reference is made to Figure 2 The first signal shaping circuit also includes a first capacitor C16 and a second capacitor C17. The first and second pins of the level conversion chip U5 are connected in parallel with the first capacitor C16; the sixth pin of the level conversion chip U5 is grounded through the second capacitor C17. Both the first capacitor C16 and the second capacitor C17 are energy storage capacitors. When the electronic switch M1 is turned on, the power supply voltage is pulled down. When a large current suddenly appears in the first signal shaping circuit, the first capacitor C16 and the second capacitor C17 can alleviate the power supply pressure on the battery.

[0064] In some possible embodiments provided by the present invention, reference is made to Figure 2 The first signal shaping circuit also includes a third resistor R19 (pull-down resistor), and the third pin of the level conversion chip U5 is grounded through the third resistor R19. If there is no input PWM signal or the pin is floating, the third resistor R19 (pull-down resistor) ensures that the third pin is in a low level state.

[0065] In some possible embodiments provided by the present invention, reference is made to Figure 2 The charge release circuit 13 includes a fourth resistor R21 and / or a second diode D11 connected in parallel with the fourth resistor R21.

[0066] As mentioned earlier, on the one hand, if the gate G is left floating (e.g., R20 is disconnected for some reason), external interference signals charge the GS junction capacitance. Even a small amount of charge can be stored there for a long time, causing the MOSFET to malfunction, i.e., turn on, or even damage the MOSFET. Therefore, a fourth resistor R21 (pull-down resistor) is needed to discharge the gate G of the electronic switch M1 to ground, preventing charge accumulation on the gate G and thus avoiding MOSFET malfunction.

[0067] On the other hand, when the MOSFET is off, the resistance between the gate and source (GS) is very high, and the capacitance between GS is very small. The voltage across the capacitor equals the charge divided by the capacitance (i.e., U = Q / C, where U is the voltage across the capacitor, Q is the charge, and C is the capacitance). According to this formula, even a small amount of static electricity can generate a very high voltage between GS. If this small amount of static electricity is not discharged in time, the high voltage across GS may cause the MOSFET to malfunction, or even break down the MOSFET's gate and source terminals. To suppress the situation where a small amount of static electricity can generate a very high voltage between GS, a first diode D9 (anti-static diode) is used.

[0068] Using the above technical solution, the first diode D9 (anti-static diode) and the fourth resistor R21 (pull-down resistor) release the charge accumulated on the gate G of the electronic switch M1 to protect the MOSFET from damage.

[0069] In some possible embodiments provided by the present invention, reference is made to Figure 2 The high voltage suppression circuit 15 includes a third diode D8, which is a high voltage suppression diode.

[0070] One end of the third diode D8 (high voltage suppression diode) is connected to the drain D of the electronic switch M1 and the other end of the oscillation circuit 14, respectively, and the other end of the third diode D8 (high voltage suppression diode) is grounded.

[0071] Since heating circuit 1 is itself a boost circuit, it has boost characteristics. On the other hand, a voltage spike is generated at the drain (D) of electronic switch M1 at the instant it is turned off. The reason for the voltage spike is that, because inductors have the characteristic of maintaining a constant current, and MOSFETs are high-speed devices with very fast switching speeds, the inductor can be considered a constant current source within a very short time, meaning the current does not change. However, the drain-source resistance of electronic switch M1 becomes very large. According to the volt-ampere formula: V = I * R, where V represents the voltage spike; I represents the current (which remains constant for a very short time); and R is the drain-source resistance. Because the drain-source resistance becomes very large within a very short time, a voltage spike is generated at the instant electronic switch M1 is turned off.

[0072] The voltage spike and the boost effect of the circuit itself create a high voltage superposition, requiring higher withstand voltage from the electronic switch M1. Therefore, a third diode D8 (high-voltage suppressor diode) is connected in parallel across the DS terminals. When the DS voltage exceeds the breakdown voltage of the third diode D8, it forms a short-circuit loop to ground, allowing high-voltage energy to be released to ground, thus protecting the electronic switch M1 from breakdown. When the DS voltage is lower than the breakdown voltage of the third diode D8, it is cut off, effectively disconnected, and will not affect the normal operation of heating circuit 1.

[0073] In some possible embodiments provided by the present invention, the high voltage suppression circuit 15 includes a third capacitor C18 and a fifth resistor R22, the third capacitor C18 and the fifth resistor R22 are connected in parallel, one end of the third capacitor C18 and the fifth resistor R22 is connected to the other end of the third diode, and the other end of the third capacitor C18 and the fifth resistor R22 is grounded.

[0074] That is, the high-voltage suppression circuit 15 includes a third diode D8 (high-voltage suppression diode), a third capacitor C18, and a fifth resistor R22. One end of the third diode D8 is connected to the drain D of the electronic switch M1 and the other end of the oscillation circuit 14, and the other end is connected in series with one end of the third capacitor C18. The other end of the third capacitor C18 is grounded. A fifth resistor R22 is connected in parallel across the two ends of the third capacitor C18. The uncharged third capacitor C18 acts as a conductor. When there is a high-voltage spike between the negative terminal of the third diode D8 (i.e., the end connected to the drain of the electronic switch M1) and ground, the third diode D8 conducts, and the high-voltage signal is released to the third capacitor C18 through the third diode D8, thereby suppressing the high voltage. When the third diode D8 is not conducting, the charge in the third capacitor C18 is released to ground through the parallel fifth resistor R22.

[0075] Using the above scheme, the third capacitor C18 in the high voltage suppression circuit 15 can suppress the current flowing through the third diode D8, preventing the third diode D8 from being damaged due to excessive current.

[0076] In some possible embodiments provided by the present invention, reference is made to Figure 2 The heating circuit also includes fourth capacitors C12, C13, and C14. One end of the fourth capacitors C12, C13, and C14 is connected to the oscillation circuit 14, and the other end is grounded. The fourth capacitors C12, C13, and C14 are energy storage capacitors. When the electronic switch M1 is turned on, the power supply voltage is pulled down. When a large current suddenly appears in the heating circuit, the fourth capacitors C12, C13, and C14 can alleviate the power supply pressure on the battery.

[0077] Specifically, pin 3 of level conversion chip U5 is connected to an external control source, receiving a low-level PWM signal (first-level PWM signal) output from the external control source. Pin 4 of level conversion chip U5 outputs a low-level PWM signal (first-level PWM signal). When the gate-source voltage (GS) of electronic switch M1 is less than the turn-on threshold, electronic switch M1 is turned off. During the turn-off process, the resistance between the drain (D) and source (S) of electronic switch M1 increases, but the current remains unchanged. Therefore, a high-voltage spike is formed between the drain (D) and source (S) of electronic switch M1. When the high-voltage spike exceeds the withstand voltage of electronic switch M1, the third diode D8 (high-voltage suppression diode) forms a short-circuit loop to ground, and the high-voltage energy can be released to ground through this channel, thereby protecting electronic switch M1 from breakdown. Furthermore, the charge release circuit 13, i.e., the first diode D9 (anti-static diode) in conjunction with the fourth resistor R21 (pull-down resistor), releases the charge accumulated at the gate (G) of electronic switch M1 to protect the MOSFET from damage.

[0078] The third pin of the level conversion chip U5 is connected to an external control source to receive a high-level PWM signal (a first-level PWM signal, such as a 3V PWM signal) output by the external control source. The fourth pin of the level conversion chip U5 outputs a high-level PWM signal (a second-level PWM signal, such as a 5.5V PWM signal). The gate voltage G of the electronic switch M1 is higher than the source voltage S. When the electronic switch M1 is turned on, the oscillation circuit 14 works normally. The oscillation circuit 14 includes an inductor L2 connected in series and resonant capacitors C9, C10 and C11. When the inductor L2 is energized, it can generate an induced current in the heating element.

[0079] In some possible embodiments provided by this invention, the frequency range of the PWM signal is 10kHz to 300kHz. By adopting the above technical solution, both the loss of the electronic switch M1 and the on-resistance of the electronic switch M1 can be reduced.

[0080] Secondly, refer to Figure 3 The present invention discloses a heating control method for use in the heating circuit 1 in any embodiment of the first aspect. The heating control method includes:

[0081] S1: Determine the initial value of the duty cycle of the first-level PWM signal output by the external control source.

[0082] S2: Determine whether the initial value is greater than or equal to the preset threshold.

[0083] If the initial value is determined to be less than a preset threshold, execute S3: increase the duty cycle by a first preset step size, and S4: determine whether the increased duty cycle is greater than or equal to the preset threshold. The duty cycle value of the first-level PWM signal is non-zero, so that the electronic switch is intermittently turned on, and the heating circuit is in working condition.

[0084] If it is determined that the increased duty cycle is greater than or equal to the preset threshold, execute S5: use the increased duty cycle as the preset threshold.

[0085] Execute S6: Start the first timer. S7: Determine if the first timer has overflowed.

[0086] If the first timer has not overflowed, execute S6 repeatedly: the first timer starts counting, and S7: check if the first timer has overflowed.

[0087] In the event of a first timer overflow, execute S8: decrease the duty cycle by a second preset step size, and S9: determine whether the decreased duty cycle is equal to zero. Specifically, when the duty cycle of the first-level PWM signal is zero, the electronic switch is turned off, and the heating circuit is in a non-operating state.

[0088] If it is determined that the reduced duty cycle is not equal to zero, repeat step S8: reduce the duty cycle by the second preset step size, and step S9: determine whether the reduced duty cycle is equal to zero. Continue until it is determined that the reduced duty cycle is equal to zero.

[0089] If the reduced duty cycle is determined to be zero, execute S10: the second timer starts counting, and S15: determine if the second timer has overflowed.

[0090] If the second timer overflows, repeat the above steps from step S1; if the second timer does not overflow, loop through S10: the second timer starts counting, and S15: determine if the second timer has overflowed.

[0091] In this embodiment, the first preset step size is a cumulative value of 1%, which gradually increases the duty cycle of the PWM signal from its initial value to a preset threshold, achieving smooth control of the PWM signal's duty cycle. The second preset step size is 1%, which gradually decreases the duty cycle of the PWM signal from the preset threshold to its initial value, achieving smooth control of the PWM signal's duty cycle. By smoothly controlling the PWM signal's duty cycle, the duty cycle of the PWM signal gradually increases from its initial value to the preset threshold or gradually decreases from the preset threshold to the initial value, that is... Figure 3 Steps S3, S4, S9, and S10 shown in the figure reduce voltage surges in the heating circuit 1 and prevent the electronic switch M1 element from being damaged.

[0092] In this embodiment, the first timer is a sustain timer. That is, in S3, when the duty cycle of the first-level PWM signal rises to a preset threshold, the first timer starts counting, maintaining the duty cycle of the first-level PWM signal at the preset threshold for a period of time, such as 20 milliseconds, until the first timer overflows. The first timer overflows when the preset sustain time, such as 20 milliseconds, has been exceeded.

[0093] In this embodiment, the second timer is an intermittent timer. That is, in S5, when the duty cycle of the first-level PWM signal drops to its initial value, the second timer starts counting, causing the duty cycle of the first-level PWM signal to remain intermittently at its initial value for a period of time, such as 5 milliseconds, until the second timer overflows. The second timer overflows when the preset intermittent time, such as 5 milliseconds, has been exceeded.

[0094] By adopting the above technical solution, the PWM signal is controlled intermittently, i.e., step S10: the second timer (i.e., the intermittent timer) starts counting; S15: it is determined whether the second timer has overflowed, so that the oscillation circuit 14 attenuates the discharge and reduces charge accumulation. Through the above heating control method, the heating circuit 1 avoids the instantaneous high voltage that would form across the switch when the single-tube drive circuit is working, which could damage or even break down the electronic switch M1 element, thus ensuring the normal operation of the electromagnetic heating circuit 1.

[0095] In some possible embodiments of the present invention, the initial value of the duty cycle is 0, and the preset threshold of the duty cycle is 90%, that is, the range of the duty cycle is 0 to 90%. Preferably, the range of the duty cycle is 0 to 74%.

[0096] In some possible embodiments provided by the present invention, after determining the initial value of the duty cycle of the first-level PWM signal output by the external control source, the heating control method further includes: S11: delaying the initial value for a first preset time. For example, the first preset time is 2 milliseconds to 10 milliseconds.

[0097] In some possible embodiments provided by the present invention, after reducing the duty cycle by a second preset step size in step S8, the heating control method further includes: S80: delaying for a second preset time at a preset threshold. For example, the second preset delay time is 2 milliseconds to 10 milliseconds.

[0098] Using the above technical solution, S11: delaying the initial value for a first preset time, or S60: delaying the preset threshold for a second preset time, is to use an external temperature detection device (such as a temperature sensor) to detect the temperature of the sensor and adjust the duty cycle of the PWM signal according to the temperature of the sensor. On the other hand, it releases the CPU space occupied by the external control source and ensures the operating speed.

[0099] refer to Figure 3In some possible embodiments provided by this invention, the method for controlling the duty cycle of the PWM signal is as follows:

[0100] S1: Determine the initial value of the duty cycle of the first-level PWM signal output by the external control source.

[0101] For example, the initial value of the duty cycle of the first-level PWM signal is 0, that is, the heating circuit 1 (e.g.) Figure 2 The energizing time of the circuit is 0 (as shown). At this time, the electronic switch M1 of the heating circuit 1 is cut off, and the heating circuit 1 is not conducting.

[0102] S11: Delay the initial value by a first preset time.

[0103] Using the above technical solution, during the first preset time of the delay, an external temperature detection device (such as a temperature sensor) is used to detect the temperature of the sensor, and the duty cycle of the PWM signal is adjusted according to the temperature of the sensor.

[0104] S2: Determine whether the initial value is greater than or equal to the preset threshold.

[0105] If the initial value is determined to be less than the preset threshold, execute S3: increase the duty cycle by the first preset step size, and S4: determine whether the increased duty cycle is greater than or equal to the preset threshold.

[0106] For example, the first preset step size is a cumulative value of 1%, so that the duty cycle of the PWM signal gradually increases from the initial value to a preset threshold. The first level of the PWM signal is high, so that the electronic switch M1 is turned on, and the heating circuit 1 is in working state. Specifically, when the first level of the PWM signal is high, the electronic switch driving circuit 11 (such as...) Figure 2 As shown, the first-level PWM signal (3V PWM signal) is converted into a second-level PWM signal (5.5V PWM signal). Electronic switch M1 receives the high-level second-level PWM signal (5.5V PWM signal) and conducts intermittently, that is, the duty cycle of the PWM signal is set to a non-zero value (and in this invention, the duty cycle is not 100%). The intermittent control oscillation circuit is heated, and an oscillation current is generated in the oscillation circuit 14 to make the heating element heat up.

[0107] By adopting the above technical solution, the duty cycle of the PWM signal is smoothly controlled, so that the duty cycle of the PWM signal gradually increases from the initial value to the preset threshold, thereby reducing voltage surges in the heating circuit 1 and preventing the electronic switch M1 component from being damaged.

[0108] If it is determined that the increased duty cycle is greater than or equal to the preset threshold, execute S5: use the increased duty cycle as the preset threshold.

[0109] Execute S6: Start the first timer. S7: Determine if the first timer has overflowed.

[0110] If the first timer has not overflowed, execute S6 repeatedly: the first timer starts counting. By using the first timer to keep the timer running, the duty cycle of the first-level PWM signal is maintained at a preset threshold for a set period of time.

[0111] S7: Determine if the first timer has overflowed.

[0112] In the event of a first timer overflow, S8 is executed: the duty cycle is reduced by a second preset step size. That is, the duty cycle of the first-level PWM signal gradually decreases. When the first-level PWM signal is low, the electronic switch M1 is turned off, and the heating circuit 1 is in a non-operating state. Specifically, when the first-level PWM signal is low, the electronic switch M1 is turned off, and the oscillation circuit 14 does not operate.

[0113] Executing S81: Delaying for a second preset time at a preset threshold. This is to use an external temperature detection device (such as a temperature sensor) to detect the temperature of the sensor and adjust the duty cycle of the PWM signal according to the sensor's temperature. On the other hand, it frees up CPU space occupied by the external control source, ensuring operating speed.

[0114] S9: Determine whether the reduced duty cycle is equal to zero.

[0115] If it is determined that the reduced duty cycle is not equal to zero, repeat step S8: reduce the duty cycle by the second preset step size, and step S9: determine whether the reduced duty cycle is equal to zero. Continue until it is determined that the reduced duty cycle is equal to zero.

[0116] Once it is determined that the reduced duty cycle is equal to zero, S10 is executed: the second timer starts counting. The second timer, i.e., the intermittent timer, maintains the duty cycle of the first-level PWM signal at its initial value for a set period of time, achieving intermittent control of the PWM signal. By intermittently controlling the PWM signal, the oscillation circuit 14 attenuates its discharge, reducing charge accumulation. Through the above heating control method, the heating circuit 1 avoids the formation of instantaneous high voltage across the switch during the operation of the single-tube drive circuit, which could damage or even break down the electronic switch M1, ensuring the normal operation of the electromagnetic heating circuit 1.

[0117] S15: Determine if the second timer has overflowed.

[0118] If the second timer overflows, repeat the above steps from step S1 until other external functional modules terminate the heating control method.

[0119] If the second timer has not overflowed, execute S10: the second timer starts counting, and S15: check if the second timer has overflowed.

[0120] Thirdly, the present invention provides an aerosol generating device, comprising: a heating circuit 1 as described in any embodiment of the first aspect above; and a heating element, wherein when the heating circuit 1 is in operation, the oscillation circuit 14 is capable of generating an induced current to cause the heating element to heat up.

[0121] Using the above technical solution, the aerosol generating device includes a heating element, and a heating circuit 1 is connected to the heating element. When the heating circuit 1 is working, the oscillation circuit 14 can generate an induced current to heat the heating element. The aerosol generating device can heat the heating element using the electromagnetic heating principle through the heating circuit 1, and the heating element heats the aerosol-generated product placed in the aerosol generating device. The heating circuit 1 avoids the instantaneous high voltage that would form across the switch when the single-tube drive circuit is working, which could damage or even break down the electronic switch M1 element, thus ensuring the normal operation of the electromagnetic heating circuit 1.

[0122] In the embodiments provided by this invention, the aerosol-generating product can be solid, liquid, or gel-like, and this invention does not limit its form. The aerosol-generating device, exemplarily, is an electronic cigarette that heats the e-liquid via heating circuit 1 to satisfy the user's inhalation experience; or it is a heated non-combustible tobacco device that heats heated cigarettes via heating circuit 1 to satisfy the user's inhalation experience, and this invention does not limit its form.

[0123] While the present invention has been illustrated and described with reference to certain preferred embodiments, those skilled in the art should understand that the above description is a further detailed explanation of the invention in conjunction with specific embodiments, and should not be construed as limiting the specific implementation of the invention to these descriptions. Various changes in form and detail can be made by those skilled in the art, including several simple deductions or substitutions, without departing from the spirit and scope of the invention.

Claims

1. A heating circuit for an aerosol generating device, characterized in that, include: An electronic switch driving circuit, one end of which is connected to an external control source, is used to receive the PWM signal output by the external control source and shape the PWM signal; Among them, PWM signal shaping includes: converting a low-voltage PWM signal into a high-voltage PWM signal, and increasing the speed of the falling edge of the PWM signal and shortening the falling edge time of the PWM signal. An electronic switch, one end of which is connected to the other end of the electronic switch driving circuit, is used to control the heating circuit to be in a working state or a non-working state according to whether the duty cycle of the shaped PWM signal output by the electronic switch driving circuit is non-zero or zero. A charge release circuit, one end of which is connected to the other end of the electronic switch driving circuit and one end of the electronic switch, and the other end of the charge release circuit is grounded; An oscillating circuit is provided, one end of which is connected to a power source and the other end of which is connected to the other end of the electronic switch. When the heating circuit is in the working state, the oscillating circuit can generate an induced current, causing the heating element in the aerosol generating device to heat up. A high-voltage suppression circuit is provided, one end of which is connected to the other end of the electronic switch and the other end of the oscillation circuit, and the other end of the high-voltage suppression circuit is grounded.

2. The heating circuit as described in claim 1, characterized in that, The electronic switch driving circuit includes: A first signal shaping circuit, one end of which is connected to the external control source, is used to receive the PWM signal output by the external control source and convert the first-level PWM signal output by the external control source into a second-level PWM signal, wherein the first level is lower than the second level.

3. The heating circuit as described in claim 2, characterized in that, The first signal shaping circuit includes a level conversion chip and a first resistor connected in series, wherein, The first pin of the level conversion chip is connected to one end of the first resistor, and the other end of the first resistor is connected to the fifth pin of the level conversion chip. The second pin of the level conversion chip is grounded; The third pin of the level conversion chip is connected to the external control source and is used to receive the first level PWM signal; The fourth pin of the level conversion chip is connected to the gate of the electronic switch and is used to control the electronic switch to turn on and off.

4. The heating circuit as described in claim 3, characterized in that, The electronic switch driving circuit also includes: A second signal shaping circuit, one end of which is connected in series with the first signal shaping circuit, and the other end of which is connected in series with the gate of the electronic switch, is used to shape the second-level PWM signal.

5. The heating circuit as described in claim 4, characterized in that, The second signal shaping circuit includes a second resistor and a first diode connected in parallel. The fourth pin of the level conversion chip is connected to one end of the second resistor and the first diode, and the other end of the second resistor and the first diode is connected to the gate of the electronic switch for controlling the conduction and cutoff of the electronic switch.

6. The heating circuit as described in claim 3, characterized in that, The first signal shaping circuit further includes a first capacitor and a second capacitor, and the first pin and the second pin of the level conversion chip are connected in parallel with the first capacitor; The sixth pin of the level conversion chip is grounded through the second capacitor.

7. The heating circuit as described in claim 3, characterized in that, The first signal shaping circuit further includes a third resistor, and the third pin of the level conversion chip is grounded through the third resistor.

8. The heating circuit as described in claim 1, characterized in that, The charge release circuit includes a fourth resistor and / or a second diode connected in parallel with the fourth resistor.

9. The heating circuit as described in claim 1, characterized in that, The high voltage suppression circuit includes a third diode, one end of which is connected to the drain of the electronic switch and the other end of the oscillation circuit, and the other end of which is grounded.

10. The heating circuit as described in claim 9, characterized in that, The high-voltage suppression circuit includes a third capacitor and a fifth resistor, which are connected in parallel. One end of the third capacitor and the fifth resistor is connected to the other end of the third diode, and the other end of the third capacitor and the fifth resistor is grounded.

11. The heating circuit as described in claim 1, characterized in that, The heating circuit also includes a fourth capacitor, one end of which is connected to one end of the oscillation circuit, and the other end of which is grounded.

12. The heating circuit as described in claim 1, characterized in that, The frequency range of the PWM signal is 10kHz to 300kHz.

13. A heating control method, characterized in that, For a heating circuit as described in any one of claims 1-11, the heating control method includes: Determine the initial value of the duty cycle of the first-level PWM signal output by the external control source; Determine whether the initial value is greater than or equal to a preset threshold; If the initial value is determined to be less than the preset threshold, the duty cycle is increased by a first preset step size, and it is determined whether the increased duty cycle is greater than or equal to the preset threshold. The duty cycle of the first level PWM signal is non-zero, so that the electronic switch is intermittently turned on and the heating circuit is in working state. If it is determined that the increased duty cycle is greater than or equal to the preset threshold, the increased duty cycle is used as the preset threshold; The first timer starts counting down; it is then determined whether the first timer has overflowed. If the first timer overflows, the duty cycle is reduced by a second preset step size, and it is determined whether the reduced duty cycle is equal to zero. The duty cycle of the first level PWM signal is zero so that the electronic switch is turned off and the heating circuit is in a non-working state. If the first timer does not overflow, the first timer starts counting repeatedly to determine whether the first timer overflows. If the reduced duty cycle is determined to be equal to zero, the second timer starts counting and it is determined whether the second timer overflows; if the reduced duty cycle is determined to be not equal to zero, the process of reducing the duty cycle by a second preset step size is repeated to determine whether the reduced duty cycle is equal to zero. If the second timer overflows, repeat the above steps; if the second timer does not overflow, repeatedly start the second timer and determine whether the second timer has overflowed.

14. The heating control method as described in claim 13, characterized in that, After the step of determining the initial value of the duty cycle of the first-level PWM signal output by the external control source, the method includes: The initial value is delayed by a first preset time.

15. The heating control method as described in claim 13, characterized in that, In the event of an overflow of the first timer, after reducing the duty cycle by a second preset step size, the heating control method further includes: The preset threshold is delayed for a second preset time.

16. An aerosol generating device, characterized in that, include: The heating circuit as described in any one of claims 1 to 12; and A heating element, wherein, when the heating circuit is in operation, the oscillating circuit can generate an induced current to cause the heating element to heat up.

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