Aerosol generating device and control method

Abstract

One embodiment of the present application proposes an aerosol generating apparatus and a control method thereof. The aerosol generating apparatus includes a susceptor configured to be penetrated by a fluctuating magnetic field and generate heat to heat an aerosol-generating product, an oscillator including an induction coil and a capacitor configured to direct a fluctuating current through the induction coil to drive the induction coil and generate the fluctuating magnetic field, a peak detection unit configured to detect a peak voltage of the oscillator, and a controller configured to control the oscillator to direct a current based on the peak voltage. The aerosol generating apparatus monitors the peak voltage during the oscillator's oscillation process, and further controls the oscillator's oscillation based on the peak voltage.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims priority to a Chinese patent application entitled "Aerosol generating apparatus and control method" filed with the China Patent Office on December 8, 2020, with application number 202011442641.4, the entire contents of which are incorporated herein by reference.

[0002] The embodiments of the present application relate to the technical field of heat-type non-combustion low-temperature smoking devices, and in particular to an aerosol generating device and a control method. [Background technology]

[0003] Tobacco products (e.g., cigarettes, cigars, etc.) burn tobacco to produce tobacco smoke during use. As an alternative to these combusted tobacco products, attempts have been made to produce products that release compounds without combustion.

[0004] An example of such a product is a heating device that releases a compound by heating a material without burning it. For example, the material may be tobacco or other non-tobacco products, which may or may not contain nicotine. In the known device, a heater that generates heat by electromagnetic induction heats the tobacco product to generate an aerosol for smoking. As one prior art related to the above heating device, the example of Chinese Patent No. 201580007754.2 proposes an induction heating device that heats a special cigarette product by electromagnetic induction, specifically, an induction coil and a capacitor are connected in series or in parallel to form an LC oscillation to form an alternating current, which generates an alternating magnetic field in the coil to induce heating of the susceptor and heat the cigarette product. Summary of the Invention

[0005] An embodiment of the present application is an aerosol generating device configured to heat an aerosol generating product to generate a smoking aerosol, comprising: a susceptor configured to be penetrated by a varying magnetic field and generate heat to heat the aerosol-generating product; an oscillator including an induction coil and a capacitor configured to direct a varying current through the induction coil to drive the induction coil to generate a varying magnetic field; a peak detection unit configured to detect a peak voltage of the oscillator; and a controller configured to control the oscillator to direct the varying current based on the peak voltage.

[0006] The aerosol generating device monitors the peak voltage during the oscillation process of the oscillator, and further controls the oscillator to conduct the fluctuating current based on the peak voltage.

[0007] Furthermore, the above circuit term "oscillator" is a circuit module that is composed of a capacitor and an inductor and can generate a periodically fluctuating current and voltage. The term "peak voltage" is the maximum value in the period of the fluctuating voltage.

[0008] In a preferred embodiment, the peak detection unit comprises: A holding capacitor configured to hold a peak voltage of the oscillator.

[0009] In a preferred embodiment, the peak detection unit comprises: an operational amplifier located between the holding capacitor and an oscillator, the operational amplifier being further configured to output the oscillator voltage to the holding capacitor; a voltage follower configured to output a peak voltage of the oscillator held by the holding capacitor.

[0010] In a preferred embodiment, the peak detection unit comprises: The power supply further includes a discharge switch configured to discharge the holding capacitor when turned on.

[0011] In a preferred embodiment, the sampling end of the operational amplifier is connected to the oscillator; The holding capacitor includes three paths, a first path of which is connected to the output terminal of the operational amplifier, a second path of which is connected to the discharge switch, and a third path of which is connected to the sampling terminal of the voltage follower.

[0012] In a preferred embodiment, the oscillator is a parallel LC oscillator including the induction coil and a capacitor connected in parallel, The controller is configured to drive the parallel LC oscillator to oscillate using pulses at a varying frequency, and determine an optimal frequency of the parallel LC oscillator based on a peak voltage detected by the peak detection unit, and further control the parallel LC oscillator to conduct the varying current based on the optimal frequency.

[0013] In a preferred embodiment, the controller is configured to determine an optimal frequency of the parallel LC oscillator based on a peak voltage detected by the peak detection unit when the peak voltage is equal to or substantially close to a preset threshold voltage.

[0014] In a preferred embodiment, in the varying frequency pulse, the frequency varies gradually from largest to smallest.

[0015] In a preferred embodiment, the oscillator is a parallel LC oscillator including the induction coil and a capacitor connected in parallel, The controller is configured to drive the parallel LC oscillator to oscillate using pulses with a varying duty ratio, and determine an optimal duty ratio of the parallel LC oscillator based on a peak voltage detected by the peak detection unit, and further control the parallel LC oscillator to conduct the varying current based on the optimal duty ratio.

[0016] In a preferred embodiment, the controller is configured to determine an optimal duty ratio of the parallel LC oscillator based on a peak voltage detected by the peak detection unit when the peak voltage is equal to or substantially close to a preset threshold voltage.

[0017] In a preferred embodiment, in the variable duty ratio pulse, the duty ratio varies gradually from smallest to largest.

[0018] In a preferred embodiment, the oscillator is a series LC oscillator or a series LCC oscillator including the induction coil and a capacitor connected in series, The controller is configured to drive the oscillator into oscillation with pulses of varying frequency, and to determine a resonant frequency of the oscillator based on a peak voltage detected by the peak detection unit.

[0019] In a preferred embodiment, the variable frequency pulse has a duty ratio of 50%, and the frequency varies gradually from largest to smallest.

[0020] In a preferred embodiment, the controller is configured to determine a resonant frequency of the oscillator based on the peak voltage detected by the peak detection unit when it is at a maximum.

[0021] Another embodiment of the present application is a susceptor configured to be penetrated by a varying magnetic field and generate heat to heat the aerosol-generating product; and an oscillator including an induction coil and a capacitor, the oscillator being configured to direct a varying current through the induction coil to drive the induction coil to generate a varying magnetic field, comprising: detecting a peak voltage of the oscillator; determining an oscillation frequency of the oscillator based on the peak voltage.

[0022] In a preferred embodiment, the oscillation frequency of the oscillator is adjusted so that the oscillation frequency remains equal to or substantially close to a preset frequency.

[0023] Another embodiment of the present application is a susceptor configured to be penetrated by a varying magnetic field and generate heat to heat the aerosol-generating product; 1. A method of controlling an aerosol generating device comprising: a parallel LC oscillator including an induction coil and a capacitor connected in parallel, the parallel LC oscillator being configured to direct a varying current through the induction coil to drive the induction coil to generate a varying magnetic field, the method comprising: Driving the parallel LC oscillator to oscillate according to a pulse whose frequency or duty ratio varies gradually; detecting a peak voltage of the parallel LC oscillator; comparing the peak voltage with a preset threshold voltage, and determining an optimal frequency or an optimal duty ratio of the parallel LC oscillator if the peak voltage is equal to or substantially close to the preset threshold voltage; driving the parallel LC oscillator to oscillate according to the optimal frequency or optimal duty ratio, and causing an induction coil to generate a varying magnetic field.

[0024] Another embodiment of the present application is a susceptor configured to be penetrated by a varying magnetic field and generate heat to heat the aerosol-generating product; 1. A method of controlling an aerosol generating device comprising: a series LC oscillator or a series LCC oscillator having an induction coil, the series LC oscillator or the series LCC oscillator being configured to direct a varying current through the induction coil to drive the induction coil to generate a varying magnetic field, the method comprising: Driving the series LC oscillator or series LCC oscillator to oscillate using a pulse having a constant duty ratio of 50% and a gradually varying frequency; detecting a peak voltage of the series LC oscillator or series LCC oscillator; determining a resonant frequency of the series LC oscillator or series LCC oscillator based on the maximum value of the peak voltage; driving the series LC oscillator or series LCC oscillator to oscillate according to the resonant frequency, and further causing an induction coil to generate a varying magnetic field.

[0025] In a preferred embodiment, in the pulses whose frequency varies gradually, the frequency varies gradually from largest to smallest.

[0026] In a preferred embodiment, the step of determining that the peak voltage is a maximum value comprises: calculating a difference between a currently detected peak voltage and a previously detected peak voltage; determining whether the difference value is positive; If the signal is positive, the frequency at which the series LC oscillator or series LCC oscillator is driven to oscillate is reduced; if not, determining that the previously detected peak voltage is a maximum value.

[0027] In a preferred embodiment, the step of reducing the frequency at which the series LC oscillator or series LCC oscillator is driven to oscillate comprises: determining whether the difference value is greater than a predetermined value, and if the difference value is greater than the predetermined value, reducing a frequency at which the series LC oscillator or the series LCC oscillator is driven to oscillate according to a first amplitude; if the difference value is not greater than the predetermined value, reducing a frequency at which the series LC oscillator or the series LCC oscillator is driven to oscillate according to a second amplitude; Here, the first amplitude is greater than the second amplitude.

[0028] Another embodiment of the present application is an aerosol generating device configured to heat an aerosol generating product to generate a smoking aerosol, comprising: a parallel LC oscillator including an induction coil and a capacitor connected in parallel, the parallel LC oscillator being configured to direct a varying current through the induction coil to drive the induction coil to generate a varying magnetic field; a susceptor configured to be penetrated by the varying magnetic field and to generate heat to further heat an aerosol-generating article received within the cavity; A transistor switch; a controller configured to control the on-off of the transistor switch with pulses and to drive the parallel LC oscillator to oscillate and direct a varying current through the induction coil; The aerosol generating device further provides, wherein the duty ratio of the pulse is greater than 50%.

[0029] In a preferred embodiment, the duty cycle of the pulse is greater than 70%. [Brief description of the drawings]

[0030] One or more embodiments are illustratively illustrated by corresponding figures in the accompanying drawings, which are not intended to be limiting of the embodiments, in which like reference numbers represent similar elements, and in which the figures are not to scale unless otherwise specified. [Figure 1] FIG. 1 is a structural schematic diagram of an aerosol generating device provided in one embodiment of the present application. [Diagram 2] FIG. 2 is a structural block diagram of one embodiment of the circuit in FIG. [Diagram 3] FIG. 3 is a schematic diagram of the basic components of one embodiment of the circuit in FIG. 2. [Figure 4] FIG. 3 is a schematic diagram of voltage and current fluctuations during oscillation of the parallel LC oscillator in FIG. 2. [Diagram 5] FIG. 4 is a schematic diagram of input and output signals of a peak detection unit in one embodiment. [Figure 6] FIG. 2 is a schematic diagram of a method for controlling an aerosol generating device according to one embodiment. [Figure 7]FIG. 13 is a schematic diagram of a method for controlling an aerosol generating device according to another embodiment. [Figure 8] 8 is a schematic diagram of an oscillation voltage in the process of sweeping the duty ratio in the control method of FIG. 7. [Figure 9] 10 is a schematic diagram of a method for controlling an aerosol generating device according to yet another embodiment. [Figure 10] FIG. 2 is a schematic diagram of the basic components of one embodiment of the circuit in FIG. 1. [Figure 11] FIG. 11 is a schematic diagram of the forward current in one stage of the LCC oscillator in FIG. [Figure 12] FIG. 11 is a schematic diagram of the reverse current in one stage of the LCC oscillator in FIG. [Figure 13] FIG. 11 is a schematic diagram of the resonant current of the series LCC oscillator in FIG. [Figure 14] FIG. 11 is a schematic diagram of the resonant current and resonant voltage fluctuations measured in the series LCC oscillator in FIG. [Figure 15] FIG. 2 is a schematic diagram of peak voltages detected in the process of driving a series LCC oscillator to oscillate using a pulse signal having a frequency varying in descending order from 333 KHz to 200 KHz in one embodiment. [Figure 16] 1 is a flowchart of a resonant frequency search using a frequency sweep method with a variable step size algorithm according to one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] In order to facilitate the understanding of the present application, the present application will now be described in more detail in conjunction with the drawings and specific embodiments.

[0032] One embodiment of the present application proposes an aerosol generating device, the structure of which is shown in FIG. a cavity in which an aerosol generating product A is removably received; an induction coil L for generating a varying magnetic field under an alternating current; a susceptor 30 extending at least partially within the cavity, the susceptor 30 being inductively coupled to the induction coil L and penetrated by a varying magnetic field to generate heat and further configured to heat an aerosol-generating product A, e.g., a cigarette, and volatilize at least one component of the aerosol-generating product A to form a smoking aerosol; A battery cell 10 which is a rechargeable DC battery cell and capable of outputting a DC current; and a circuit 20 that is appropriately electrically connected to the rechargeable battery cell 10 to convert the direct current output from the battery cell 10 into an alternating current having an appropriate frequency and then supplying it to the induction coil L.

[0033] Depending on the configuration of the product in use, the induction coil L may include a helically wound cylindrical inductor coil as shown in FIG. 1. The helically wound cylindrical induction coil L may have a radius r in the range of about 5 mm to about 10 mm, and in particular the radius r may be about 7 mm. The length of the helically wound cylindrical induction coil L may be in the range of about 8 mm to about 14 mm, and the number of turns of the induction coil L is in the range of about 8 turns to 15 turns. Accordingly, the internal volume is about 0.15 cm. 3 From about 1.10 cm 3 may be in the range.

[0034] In a more preferred embodiment, the frequency of the alternating current supplied from the circuit 20 to the induction coil L is in the range of 80KHz to 400KHz, and more specifically, said frequency may be in the range of about 200KHz to 300KHz.

[0035] In one preferred embodiment, the DC power supply voltage provided by the battery cell 10 is in the range of about 2.5V to about 9.0V, and the amperage of the DC current capable of being provided by the battery cell 10 is in the range of about 2.5A to about 20A.

[0036] In a preferred embodiment, the susceptor 30 is generally pin- or blade-shaped, which is advantageous for insertion into the aerosol-generating product A. The susceptor 30 may have a length of about 12 millimeters, a width of about 4 millimeters, and a thickness of about 0.5 millimeters, and may be made of grade 430 stainless steel (SS430). As an alternative embodiment, the susceptor 30 may have a length of about 12 millimeters, a width of about 5 millimeters, and a thickness of about 0.5 millimeters, and may be made of grade 430 stainless steel (SS430). In another modified embodiment, the susceptor 30 may be further constructed in a cylindrical or tubular shape. In use, its internal space forms a cavity for receiving the aerosol-generating product A, and generates an aerosol for smoking in a manner that heats the outer periphery of the aerosol-generating product A. These susceptors may further be made of grade 420 stainless steel (SS420) and iron / nickel-containing alloy materials (e.g., permalloy).

[0037] In the embodiment shown in Fig. 1, the aerosol generating device further includes a holder 40 for disposing the induction coil L and the susceptor 30, and the material of the holder 40 may include a non-metallic material that can withstand high temperatures, such as PEEK or ceramic. In practice, the induction coil L is wound and fixed on the outer wall of the holder 40. As shown in Fig. 1, the holder 40 has a hollow tubular shape, and the space of the hollow part of the tubular shape forms the above-mentioned cavity for receiving the aerosol generating product A.

[0038] In an alternative embodiment, the susceptor 30 is fabricated from one of the susceptible materials listed above or comprises a heat-resistant substrate, such as a ceramic, having a susceptible material coating formed thereon by electroplating or deposition.

[0039] The structure and basic components of a preferred embodiment of the above circuit 20 include the following: a parallel LC oscillator 24, a transistor switch 23, as shown in FIGS.

[0040] Specifically, the parallel LC oscillator 24 is composed of a capacitor C1 and an induction coil L connected in parallel, and oscillates with a provided pulse voltage to generate a fluctuating current that is supplied to the induction coil L, thereby generating a fluctuating magnetic field to induce heat in the susceptor 30.

[0041] The transistor switch 23 includes a switch tube Q1, which is alternately turned on and off to conduct current between the battery cell 10 and the parallel LC oscillator 24 to oscillate the parallel LC oscillator 24 and generate a varying current through the induction coil L, thereby generating a varying magnetic field in the induction coil L. Of course, in the preferred embodiment shown in FIG. 3, the switch tube Q1 is a typical MOS transistor switch, and during connection, the MOS transistor switch is turned on and off by receiving a PWM drive signal from the switch tube driver 22 via a gate G.

[0042] Furthermore, in a preferred embodiment, the on / off of the transistor switch 23 is controlled by a drive signal of the switch tube driver 22. Naturally, the drive signal of the switch tube driver 22 is generated based on a PWM type pulse control signal received from the MCU controller 21.

[0043] In a preferred embodiment, the on-time and off-time of the switch tube Q1 are different, that is, the duty ratio for controlling the parallel LC oscillator 24 to oscillate in a PWM manner is not 50%. That is, the oscillation process of the parallel LC oscillator 24 is asymmetric, and the parallel LC oscillator 24 is maintained to have a sufficient oscillation voltage holding magnetic field strength. In a preferred embodiment, the duty ratio for controlling the switch tube Q1 to be on in a PWM manner is about 70-80%. Specifically, FIG. 4 shows the fluctuation process of the oscillation current / voltage in one period from time t1 to t5 when the parallel LC oscillator 24 of the circuit 20 shown in FIG. 3 is driven in a symmetric resonance manner with a duty ratio of 50%, which includes the following S1, S2, S3, and S4.

[0044] In S1, in the time period from t1 to t2, the switch tube driver 22 transmits a PWM pulse drive signal to the gate G of the MOS transistor Q1 to saturate the MOS transistor and turn it on. After turning it on, a current i1 flows from the positive electrode of the battery cell 10 through the induction coil L, and since the current cannot suddenly change due to the inductive reactance of the coil, the induction coil L is charged and a linearly increasing current i1 is formed in the time period from t1 to t2.

[0045] In S2, during the time period from t2 to t3, at time t2, the PWM pulse ends and the MOS transistor Q1 is turned off. Similarly, due to the inductive reactance effect of the induction coil L, the current cannot instantly become 0, and the capacitor C1 is charged so that a current i2 that charges the capacitor C1 is generated.

[0046] At time t3, the capacitor C1 is filled with charge and the current becomes 0. In this case, the magnetic field energy of the induction coil L is converted into the electric field energy of the capacitor C1, and the voltage formed between the drain D and source S of the MOS transistor Q1 is actually the sum of the reverse phase pulse peak voltage and the positive output voltage of the battery cell 10.

[0047] In S3, during the time period t3 to t4, the capacitor C1 is discharged by the induction coil L until it is completed, i3 reaches a maximum value, and the voltage across the capacitor C1 gradually decreases until it disappears, in which case the electrical energy in the capacitor C1 is also converted into magnetic energy in the induction coil L. Similarly, due to the inductive reactance effect, the current flowing through the induction coil L gradually changes, and is in the opposite direction to the above S1 and S2. The capacitor C1 is discharged until the electromotive force across the induction coil L is in the opposite direction.

[0048] In S4, during the time period from t4 to t5, when the MOS transistor Q1 is turned on again at time t4, a reflux is formed between the induction coil L and the filter capacitor C3, in which case the energy of the induction coil L is kicked back to the filter capacitor C3 to form a gradually decreasing current i4, which decreases to 0 at time t5, ending the cycle. After that, the next oscillation cycle begins.

[0049] As can be seen from the above process, at time t4, the voltage between the drain D and source S of the MOS transistor Q1 crosses zero, and the MOS transistor Q1 switches between on and off states depending on the zero-crossing point of the voltage between the drain D and source S during the oscillation process.

[0050] 3 and 4, the synchronous detection unit 25 is for detecting the oscillation voltage of the parallel LC oscillator 24. Specifically, as shown in FIG. 3, the synchronous detection unit 25 mainly includes: a zero-cross comparator U1 for sampling and detecting the zero-cross point of the drain D voltage signal of the MOS transistor Q1, so that only the MCU controller 21 controls the on / off switching of the MOS transistor Q1 according to the zero-cross time point.

[0051] The embodiment of FIG. 3 and FIG. 4 further provides a peak detection unit 26 for detecting the peak voltage of the parallel LC oscillator 24 and controlling the output, which mainly includes the following operational amplifier U2, a holding capacitor C2, and a voltage follower U3.

[0052] The operational amplifier U2 has its sampling terminal in- connected to the drain D of the MOS transistor Q1, and is used to sample the voltage of the drain D of the MOS transistor Q1 and output the calculation result via the diode D2.

[0053] The holding capacitor C2 is connected to the output terminal of the operational amplifier U2, and the peak voltage output from the operational amplifier U2 can be held or locked by the holding capacitor C2. For example, in the time period t2 to t3 of the voltage fluctuation cycle shown in FIG. 4, the operational amplifier U2 outputs a gradually increasing voltage value, and the holding capacitor C2 receives and stores the output voltage, and the voltage across the holding capacitor C2 synchronously becomes maximum until the voltage value output from the operational amplifier U2 becomes maximum at the time t3. After the time t3 has passed, the output from the operational amplifier U2 gradually decreases to 0. However, since the holding capacitor C2 does not discharge, the voltage value across both ends is always held at a peak.

[0054] Voltage follower U3 outputs a voltage that tracks the peak voltage held by holding capacitor C2.

[0055] FIG. 5 shows the contrast between the input signal collected by the sampling terminal in- of the operational amplifier U2 of the peak detection unit 26 and the output signal output from the output terminal of the voltage follower U3 in two oscillation periods in which the parallel LC oscillator 24 is driven with a duty ratio of 70%. As can be seen from FIG. 5, what the peak detection unit 26 outputs is always the peak voltage of the parallel LC oscillator 24. Also, as can be seen from the waveform of the input signal in FIG. 5, the time length in which the voltage peak appears in the input signal is much smaller than the time length substantially close to 0, that is, the oscillation is asymmetric. And, as can be seen from the shape of the voltage peak in FIG. 5, the length of time (t3) for the voltage to rise from substantially close to 0 (t2) to the peak voltage is different from the length of time for the voltage to fall from the peak voltage to a voltage substantially close to 0 (t4). Specifically, in FIG. 5, the speed of rising to the peak is fast, and the speed of falling from the peak is slow. Compared with the symmetrical resonance with a duty ratio of 50% in FIG. 4, the adoption of an asymmetrical peak voltage that is much larger than the voltage at a duty ratio of 50% can further compensate for the low efficiency problem caused by the short charging time of the induction coil L in the process of driving the parallel LC oscillator 24 to oscillate at a duty ratio of 50%. Based on the above tests of this application, in a preferred embodiment, the parallel LC oscillator 24 is driven to oscillate and heat with a pulse with a duty ratio of more than 50%. In a more preferred embodiment, the duty ratio is more than 70%. By lengthening the charging time and shortening the discharging time in the oscillation cycle, the required power and voltage can be maintained.

[0056] By using the above-mentioned holding capacitor C2 and voltage follower U3, the output peak voltage can be always held at any point in the oscillation process, and the MCU controller 21 can acquire or sample and detect the peak voltage of the oscillation at any point.

[0057] In the preferred embodiment shown in Fig. 3, the operational amplifier U2 is used in the basic usage manner of a comparator. Specifically, when the reference signal input terminal in+ of the operational amplifier U2 is connected to one fixed signal of the output signal through one capacitor, the operational amplifier U2, as a comparator, outputs the result of the comparison operation between the oscillation voltage signal of the parallel LC oscillator 24 and the fixed reference signal. That is, when the voltage signal sampled at the sampling terminal in- of the operational amplifier U2 is higher than the reference voltage signal input at the input terminal in+, the operational amplifier U2 outputs the comparison result to the holding capacitor C2 for holding, and when the voltage signal sampled at the sampling terminal in- reaches a peak, the voltage received by the holding capacitor C2 becomes maximum, i.e., the peak voltage.

[0058] Furthermore, in the preferred embodiment shown in Figure 3, the sampling terminal in+ of the voltage follower U3 is connected to the sampling terminal in+ of the operational amplifier U2 through the conventional tracking output connection manner. In addition, the peak detection unit 26 further includes a number of basic elements such as resistors, capacitors, etc., which are used for the functions of basic voltage division, voltage stabilization, and current limiting.

[0059] Specifically, in the embodiment shown in FIG. 3, the negative end of the holding capacitor C2 in the peak detection unit 26 is grounded, and the positive end connection includes three paths.

[0060] The first path is connected to the output of the operational amplifier U2 for receiving the voltage output by the operational amplifier U2.

[0061] In the second path, the sampling terminal in- of the voltage follower U3 is connected so that the voltage follower U3 can output the peak voltage held by the holding capacitor C2.

[0062] The third path is grounded via a switch tube Q2, and the MCU controller 21 discharges the positive end of the holding capacitor C2 to 0 by turning on the switch tube Q2 so as to facilitate sampling of the next oscillation peak voltage.

[0063] Another embodiment of the present application further provides a control method for automatically detecting or adjusting the oscillation frequency or duty ratio of the pulse control signal of the aerosol generating device based on the above peak detection unit 26.

[0064] FIG. 6 shows steps of a method for automatically detecting and adjusting an oscillation frequency adapted to a predetermined duty ratio in an aerosol generating device, and includes the following steps S10 and S20.

[0065] At S10, using a predetermined duty ratio, the MCU controller 21 sends a series of pulse signals with gradually varying frequencies to the switch tube driver 22 to drive the switch tube Q1 on / off, and further drives the parallel LC oscillator 24 to oscillate.

[0066] In S20, during the implementation of the above step S10, the peak voltage of the parallel LC oscillator 24 is measured by the peak detection unit 26, and if the measured peak voltage is equal to or very close to a preset voltage threshold, a desired optimal oscillation frequency is determined, and then the MCU controller 21 inductively heats the susceptor 30 based on the determined optimal oscillation frequency.

[0067] In the above step S10, after setting a constant duty ratio (e.g., 50% or 70%), a series of pulse signals including a gradually changing frequency are emitted to drive the parallel LC oscillator 24 to oscillate, an optimal combination of frequency and duty ratio suitable for the desired output power is searched for by frequency sweep, and then the parallel LC oscillator 24 is driven to oscillate in accordance with this optimal frequency and duty ratio, and further controlled so that the susceptor 30 generates heat.

[0068] In the above preferred embodiment, as the pulse signal for frequency sweeping, it is preferred that the frequency of the pulse signal gradually decreases in ascending order. When the duty ratio set in the frequency sweeping is constant, the higher the frequency, the shorter the corresponding period, and the peak voltage of oscillation is proportional to the total current, where the total current I is the integral of the current i and time t, and is Σ(di / dt). Accordingly, the peak voltage detected in the frequency sweeping process varies in descending order, which is advantageous for safely finding the frequency at the preset voltage threshold.

[0069] In practice, the number or number of pulses included in the pulse signal for frequency sweeping is kept between 5-50, and preferably between 5-10.

[0070] In a preferred embodiment, during the frequency sweep process, each time a peak voltage is detected, the switch tube Q2 is turned on to discharge the positive end of the holding capacitor C2 to zero, and the peak detection unit 26 is reset.

[0071] In the detection target where the circuit 20 operates, it is practically unlikely that the peak voltage is measured exactly the same as the preset voltage threshold, and moreover, according to practical experience, it is usually reasonable to determine that they are substantially close or very close by determining the detection result by making the error between the two less than 0.25% of the preset voltage threshold. For example, when the voltage peak at the ideal optimum oscillation efficiency is 40V, if the peak voltage detected in the actual frequency sweep measurement is 39V or more, it is almost considered that the optimum frequency has been found. Of course, in other optional embodiments, when there may be variations in each component and data stability during the operation of the circuit 20, the error judgment criteria between the two may be further reduced if more accurate results can be achieved, for example, the error between the two may be less than 0.1% of the preset voltage threshold.

[0072] FIG. 7 shows steps of a method for controlling an aerosol generating device in another embodiment for automatically detecting the duty ratio of a control signal of the parallel LC oscillator 24 that matches a predetermined frequency, and includes the following steps S11 and S21.

[0073] In S11, using a predetermined frequency, the MCU controller 21 generates a series of pulse signals with gradually changing duty ratios to control the switch tube Q1 to turn on / off, and further drives the parallel LC oscillator 24 to oscillate. The above preset frequencies are, for example, 200KHz / 300KHz / 350KHz, etc., and of course, the predetermined frequency is constant during the process of sweeping the duty ratio.

[0074] In S21, during the implementation of the above step S11, the peak voltage of the parallel LC oscillator 24 is measured by the peak detection unit 26, and if the measured peak voltage is equal to or very close to a preset voltage threshold, it is determined that the duty ratio corresponding to the peak voltage in this case is the optimal duty ratio for the selected frequency, and then the parallel LC oscillator 24 is driven to oscillate according to the pulse signal of the duty ratio, and the susceptor 30 is inductively heated.

[0075] In the above preferred embodiment, as the pulse signal for the duty ratio sweep, its duty ratio gradually increases from small to large. When the frequency is constant during the duty ratio sweep process, the larger the duty ratio, the longer the on-time of the corresponding switch tube Q1. Accordingly, the peak voltage detected during the duty ratio sweep process fluctuates from small to large, which is favorable for safely finding the frequency at the preset voltage threshold. Similarly, every time a peak voltage is detected during the detection process, the switch tube Q2 is turned on to discharge the positive end of the holding capacitor C2 to 0, and the peak detection unit 26 is reset.

[0076] In a specific embodiment, FIG. 8 shows a waveform diagram of an oscillation voltage in a pulse signal with a predetermined frequency of 200KHz (i.e., a period of 5us) and a threshold voltage of 40V, which is swept and searched for by sweeping the duty ratio. Starting with an on-time of 2μs (i.e., a duty ratio of 2μs / 5μs=40%) of the switch tube Q1, the duty ratio is swept by increasing the on-time by 0.2μs for each pulse. When the on-time is swept to 3.6μs, the peak voltage is closest to 20V. Then, the parallel LC oscillator 24 is driven to oscillate with a duty ratio of 3.6μs / 5μs=72% and a frequency of 200KHz, which is optimal for obtaining the desired heating efficiency.

[0077] Here, the threshold voltage of 40V is set based on the heating efficiency required for the product of one embodiment, and the value is taken from the experience during the test run of the prototype, and this value not only ensures rapid heating, but also does not damage the inverter circuit and ensures a margin of about 25%.

[0078] In yet another embodiment, if the heating temperature or heating efficiency desired by the user changes, or if the aerosol generating product A is replaced with one requiring a different heating temperature, the required threshold voltage may be further adjusted and the frequency may be swept again as described above, or the duty ratio may be swept again to find a frequency or duty ratio suitable for the desired heating temperature or heating efficiency.

[0079] In the above method of the present application, the peak detection unit 26 can detect the peak voltage during the oscillation process, and the peak voltage of the oscillation is correlated with the heating efficiency. Furthermore, the method can automatically find the appropriate driving frequency or duty ratio according to the product or demand.

[0080] Another embodiment of the present application further provides a control method for an aerosol generating device for self-adaptively adjusting an oscillation frequency, as shown in FIG. 9, which includes the following steps S12 and S22.

[0081] In S12, the peak detection unit 26 detects the oscillation peak voltage of the parallel LC oscillator 24.

[0082] At S22, the MCU controller 21 determines the current oscillation frequency of the parallel LC oscillator 24 based on the detected oscillation peak voltage, and adjusts the magnitude of the drive frequency provided to the parallel LC oscillator 24 so that the oscillation frequency remains equal to or substantially close to the desired optimal frequency.

[0083] In this embodiment, the current oscillation frequency is back-calculated based on the correlation between the peak voltage and frequency detected by the peak detection unit 26, and then the output frequency is self-adaptively adjusted to be equal to or substantially close to the preset oscillation frequency. In implementation, the object to be applied or detected can be applied to a series LC oscillator.

[0084] For example, FIG. 10 shows the structure and basic components of a circuit 20 of a series LCC oscillator 24a according to another embodiment of the present application, which achieves resonance and further generates an alternating magnetic field in an induction coil L therein.

[0085] Here, in the oscillation process of the series LCC oscillator 24a, commutation is controlled by a half bridge consisting of the switch tube Q3 and the switch tube Q4. The on-off switching of the switch tube Q3 and the switch tube Q4 is controlled by the switch tube driver 22a. Specifically, the oscillation process of the series LCC oscillator 24a includes the following steps S100, S200, S300, and S400, as shown in Figures 11 and 12.

[0086] In step S100, as shown in Fig. 11, when the switch tube Q3 is turned on and the switch tube Q4 is turned off, the battery cell 10 charges the capacitor C4 with a current i1, and the capacitor C3 discharges with a current i2, and in this process, a current flows through the induction coil L from left to right as shown in Fig. 11, which can be a positive current. In step S100, the capacitor C3 starts discharging when the switch tube Q3 is turned on, and completes discharging until the voltage difference between both ends becomes 0, and stops charging until the voltage between both ends of the capacitor C4 becomes equal to the output voltage of the battery cell 10, and at this time, the current in the induction coil L reaches its maximum resonant peak.

[0087] In S200, even after the completion of step S100, the switch tube Q3 is still turned on and the switch tube Q4 is still turned off, and the induction coil L discharges in the same direction as the current i2 in FIG. 1 to charge the capacitor C3, thereby gradually reducing the current flowing in the forward direction through the induction coil L until the current becomes 0 due to the discharge of the induction coil L. At this stage, since the discharge of the capacitor C3 is completed in step S100, there is essentially no impedance between the induction coil L and the circuit formed with the capacitor C3 via the switch tube Q3, so that in this stage S200, the induction coil L mainly discharges and charges the capacitor C3, and the current flowing through the induction coil L during the discharge process is the same as the current i2 in step S100. The capacitor C4 is charged to the output voltage substantially the same as that of the battery cell 10 in step S100, and in this stage S200, the induction coil L compensates the second capacitor C2 very slightly, but it can basically be ignored.

[0088] During the complete process of steps S100 and S200, the total current flowing through the induction coil L increases in a positive direction from 0 to a maximum, and then gradually decreases to 0 due to the discharge of the induction coil L, and the direction of the current flowing through the induction coil L is always a positive direction from left to right.

[0089] In S300, after step S200 is completed, the switch tube Q3 is turned off and the switch tube Q4 is turned on. When the switch tube Q2 is turned on, a circuit of the current i3 and the current i4 shown in FIG. 12 is formed in the LCC oscillator 24a. According to the current path shown in FIG. 12, the current i3 forms a circuit from the positive electrode of the battery cell 10 through the capacitor C3, the induction coil L, the switch tube Q4, and then returns to the negative electrode of the battery cell 10 via grounding. In addition, the current i4 forms a circuit from the positive end of the capacitor C4 through the induction coil L and the switch tube Q4 in the counterclockwise direction shown in the figure, and then returns to the negative end of the capacitor C4. In this process, a current is formed that flows through the induction coil L from right to left as shown in FIG. 12, which is the opposite of the current direction in FIG. 11 and can be a negative current.

[0090] Step S300 involves simultaneously charging the capacitor C3 and discharging the capacitor C4. When the voltage of the capacitor C3 increases to be equal to the output voltage of the battery cell 10 and the voltage difference across the capacitor C4 is zero, the current in the induction coil L reaches a maximum resonant peak.

[0091] In S400, after completion of step S300, switch tube Q2 continues to be turned on, and induction coil L reverse charges capacitor C4, thereby gradually decreasing the current flowing through induction coil L in the negative direction until the current is zero due to the discharge of induction coil L.

[0092] During the complete course of steps S300 and S400, the total current through the induction coil L similarly increases in the reverse direction from 0 to a maximum and then gradually decreases back to 0 due to the discharge of the induction coil L.

[0093] Therefore, in the above oscillation process of the LCC oscillator 24a, the fluctuation of the current flowing through the induction coil L, as shown in Fig. 13, one complete current cycle includes four parts corresponding to the above steps S100 / S200 / S300 / S400 in Fig. 13. In the above steps S100 to S400, the on / off states of the switch tube Q3 and the switch tube Q4 are alternately and cyclically switched, so that the above oscillation process is cyclically generated in the LCC oscillator 24a, and an alternating current flowing through the induction coil L can be formed.

[0094] Therefore, as can be seen from the above control process, the LCC oscillator 24a in this embodiment generates an inverse conversion by a ZCS (zero current switch) inverter topology, which is different from the ZVS (zero voltage switch) inverter topology of the above parallel LC oscillator 24. And the switch tube Q3 and the switch tube Q4 are configured to switch on / off when the current flowing through the induction coil L is zero.

[0095] The commutation during the oscillation of the above LCC oscillator 24a is controlled by a half bridge consisting of switch tube Q3 and switch tube Q4. Of course, based on the same embodiment, engineers can replace or adopt a full bridge circuit including four switch tubes to drive the oscillation of the LCC oscillator 24a.

[0096] Further referring to the embodiment shown in FIG. 3, the half-bridge driver 22a adopts a switch tube driver of a common model number FD2204, which is controlled by the MCU controller 21 in a PWM manner, and outputs high level / low level alternately through the third and tenth I / O ports according to the pulse width of the PWM, and further drives the on-time of the switch tube Q3 and the switch tube Q4 to control the oscillation of the LCC oscillator 24a.

[0097] And, as can be seen from the above process, in the oscillation process of the above series LCC oscillator 24a, the current or voltage is a sine or cosine resonance change curve having symmetry, the duty ratio is substantially constant at 50%, and the corresponding MCU controller 21 drives the switch tube Q3 and the switch tube Q4 on or off with a PWM pulse signal with a duty ratio of 50%. In practice, the intensities of the resonance voltage and current progress in correlation with each other, for example, fluctuating as shown in FIG. 14. The resonance voltage advances about 1 / 4 of the period ahead of the resonance current, and the whole LCC oscillator 24a shows weak inductivity. "Capacitive" and "inductive" are electrical terms related to a series-parallel circuit of an electronic device (for example, an LC oscillator or the above LCC oscillator 24a). If the capacitive reactance of a series-parallel circuit is larger than the inductive reactance, the circuit is "capacitive", and if the inductive reactance is larger than the capacitive reactance, the circuit is inductive. A "weakly inductive" condition is one in which the inductive reactance and the capacitive reactance are substantially close, and the inductive reactance is slightly greater than the capacitive reactance rather than much greater than it.

[0098] Similarly, in the embodiment shown in FIG. 10, the circuit 20 further includes a peak detection unit 26a for detecting the peak voltage of the LCC oscillator 24a.

[0099] In the embodiment shown in FIG. 10 above, several conventional basic elements are also included, such as resistors for voltage division, current limiting, and diodes for blocking reverse current, as well as capacitors for voltage stabilization or filtering.

[0100] Furthermore, the MCU controller 21 of the aerosol generator can also use the detection of the peak detection unit 26a to search for the frequency of the optimal output power or heating efficiency by a frequency sweeping method. In a specific embodiment, similar to the frequency sweeping of the parallel LC oscillator 24, a series of pulse signals of variable frequencies are generated to drive the LCC oscillator 24a to oscillate, and the resonance frequency of the LCC oscillator 24a is determined based on the maximum of the detected peak voltages themselves, and the LCC oscillator 24a is controlled to oscillate at the resonance frequency obtained by the frequency sweeping, thereby inductively heating the susceptor 30.

[0101] Naturally, during the frequency sweep process of the LCC oscillator 24a, the LCC oscillator 24a itself is a sinusoidal resonance with a duty ratio of 50%. Therefore, during the corresponding frequency sweep process, when the driving frequency is equal to or very close to the resonant frequency of the LCC oscillator 24a, the resonant voltage can be maximized. When the driving frequency deviates from the resonant frequency of the LCC oscillator 24a, the resonant voltage becomes smaller and smaller. Only when the driving frequency is equal to or very close to the resonant frequency, the LCC oscillator 24a will be substantially fully resonant, and in this case, the resonant voltage can be achieved. That is, there is an obvious correspondence between the driving frequency and the resonant voltage when it is higher than the resonant frequency.

[0102] For example, FIG. 15 shows a diagram of peak voltages detected when sweeping the frequency from 333KHz to 200KHz in ascending order in one embodiment. In the frequency sweep process, the peak voltage gradually increases and reaches a maximum in the range of 217KHz to 227KHz. If the driving frequency continues to be reduced to 200KHz, the peak voltage decreases. Under relatively relaxed or vague accuracy requirements, the range of 217KHz to 227KHz is considered to be the resonant frequency range of the LCC oscillator 24a in this embodiment. Depending on the need for accuracy, the user can select the width of each frequency adjustment in the frequency sweep in practice, and of course, the larger the width, the lower the accuracy, but the shorter the frequency sweep time and the faster the detection efficiency. On the other hand, the smaller the width of each adjustment, the higher the accuracy, but the longer the time and the lower the efficiency. In an optional embodiment, it is appropriate to sweep the frequency with an adjustment width of 1 to 30KHz.

[0103] Of course, if it is necessary to further improve the accuracy of the detected resonant frequency, the above frequency sweep operation can be further continued between 217KHz and 227KHz at a frequency change rate of 0.5KHz until the frequency of the maximum peak voltage, i.e., a more accurate resonant frequency, is found.

[0104] In view of the above, another embodiment of the present application further provides a frequency sweep method for quickly searching for a resonant frequency by a variable step size algorithm. As shown in Fig. 16, the steps of the method include the following steps S1000, S2000, S3000, S4000, S5000, S5100, and S5200.

[0105] In S1000, a frequency sweep is started from the set initial frequency value.

[0106] In S2000, the LCC oscillator 24a is driven to oscillate at the current sweep frequency.

[0107] In S3000, the peak voltage during the current oscillation of the LCC oscillator 24a is detected, and the difference between this peak voltage and the peak voltage detected previously is calculated.

[0108] In S4000, it is determined whether the calculated difference value is a positive value, and if it is a positive value, step S5000 is further executed, and if it is not a positive value, it is determined that the current sweep frequency is the resonant frequency to be searched for.

[0109] In S5000, it is determined whether the above difference value is greater than a predetermined value, and if so, step S5100 is executed, and if not, step S5200 is executed.

[0110] In S5100, the sweep frequency is decreased according to the first amplitude to continue the frequency sweep.

[0111] In S5200, the frequency sweep is continued by decreasing the sweep frequency according to the second amplitude.

[0112] Here, the first amplitude is greater than the second amplitude, and for example, the first amplitude may be 5KHz / 10KHz / 15KHz / 20KHz / 22KHz / 25KHz / 30KHz, etc., and the second amplitude may be 0.5KHz / 1KHz / 1.5KHz / 2KHz / 5KHz, etc.

[0113] In the above embodiment, by utilizing the peak voltage detection and fast search algorithm, the frequency reduction amount is automatically adjusted during the frequency sweep process based on the magnitude of the difference between the current peak voltage and the previous peak voltage. When the two adjacent detected peak voltages tend to be more and more the same, the reduction amount of the sweep frequency becomes smaller and smaller. The time can be greatly shortened in the early stage, and the accuracy can be greatly improved in the later stage. Furthermore, it is possible to quickly and accurately capture the resonant frequency of the LCC oscillator 24a before the initial heating.

[0114] In another modified embodiment, the series LC oscillator and the LCC oscillator 24a have similar processes, and the voltage / current during the oscillation process are similarly symmetrical sine or cosine resonance change curves. The series LC oscillator also has the highest efficiency at resonance. Furthermore, according to the above frequency sweep and peak voltage detection methods, both can be used to control an aerosol generator with a series LC oscillator.

[0115] It should be noted that although the specification and drawings of this application show preferred embodiments of the present application, the present application is not limited to the embodiments described in the present specification, and further, a person skilled in the art may make improvements or modifications based on the above description, and all such improvements and modifications are within the scope of protection of the claims attached to this application.

Claims

1. 1. An aerosol generating device configured to heat an aerosol generating product to generate a smoking aerosol, comprising: a susceptor configured to be penetrated by a varying magnetic field and generate heat to heat the aerosol-generating product; a parallel LC oscillator including an induction coil and a capacitor connected in parallel, the parallel LC oscillator being configured to direct a varying current through the induction coil to drive the induction coil to generate a varying magnetic field; a peak detection unit configured to detect a peak voltage of the parallel LC oscillator; configured to drive the parallel LC oscillator to oscillate using pulses at a varying frequency, and determine an optimal frequency of the parallel LC oscillator based on a peak voltage detected by the peak detection unit, and further control the parallel LC oscillator to conduct the varying current based on the optimal frequency; and / or an aerosol generating device comprising: a controller configured to drive the parallel LC oscillator to oscillate using a pulse with a varying duty ratio, determine an optimal duty ratio of the parallel LC oscillator based on a peak voltage detected by the peak detection unit, and further control the parallel LC oscillator to conduct the varying current based on the optimal duty ratio.

2. The aerosol generating device of claim 1, wherein the controller is configured to determine an optimal frequency of the parallel LC oscillator based on a peak voltage detected by the peak detection unit when the peak voltage is equal to or substantially close to a preset threshold voltage.

3. 2. The aerosol generating device according to claim 1, wherein in the varying frequency pulse, the frequency varies gradually from largest to smallest.

4. The aerosol generating device of claim 1, wherein the controller is configured to determine an optimal duty ratio of the parallel LC oscillator based on a peak voltage detected by the peak detection unit when the peak voltage is equal to or substantially close to a preset threshold voltage.

5. 2. The aerosol generating device according to claim 1, wherein in the pulse with the varying duty ratio, the duty ratio varies gradually from smaller to larger.

6. An aerosol generating device as described in claim 1, wherein the variable duty ratio is greater than 50%.

7. An aerosol generating device as described in claim 6, wherein the variable duty ratio is greater than 70%.

8. An aerosol generating device configured to heat an aerosol generating product to generate a smoking aerosol, comprising: a susceptor configured to be penetrated by a varying magnetic field and generate heat to heat the aerosol-generating product; an oscillator, which is a series LC oscillator or a series LCC oscillator, including an induction coil and a capacitor connected in series, configured to direct a varying current through the induction coil to drive the induction coil to generate a varying magnetic field; a peak detection unit configured to detect a peak voltage of the oscillator; and a controller configured to drive the oscillator to oscillate using a pulse whose frequency gradually changes, detect a peak voltage of the oscillator, calculate a difference between the currently detected peak voltage and the previously detected peak voltage, determine whether the difference is positive or not, and if so, reduce a frequency at which the oscillator is driven to oscillate, and if not, determine that the previously detected peak voltage is a maximum value, determine a resonant frequency of the oscillator based on the maximum value of the peak voltage, drive the oscillator to oscillate in accordance with the resonant frequency, and further generate a varying magnetic field in an induction coil.

9. An aerosol generating device as described in claim 8, wherein in the pulse in which the frequency gradually changes, the frequency gradually changes from largest to smallest.

10. Reducing the frequency at which the oscillator is driven to oscillate comprises: determining whether the difference value is greater than a predetermined value, and if the difference value is greater than the predetermined value, reducing a frequency at which the oscillator is driven to oscillate according to a first amplitude, and if the difference value is not greater than the predetermined value, reducing a frequency at which the oscillator is driven to oscillate according to a second amplitude; The aerosol generating device of claim 8 , wherein the first amplitude is greater than the second amplitude.

11. An aerosol generating device configured to heat an aerosol generating product to generate a smoking aerosol, comprising: a susceptor configured to be penetrated by a varying magnetic field and generate heat to heat the aerosol-generating product; an oscillator including an induction coil and a capacitor, the oscillator being configured to direct a varying current through the induction coil to drive the induction coil to generate a varying magnetic field; and a peak detection unit configured to detect a peak voltage of the oscillator; A controller configured to detect a peak voltage of the oscillator, determine an oscillation frequency of the oscillator based on the peak voltage, and adjust the oscillation frequency of the oscillator so that the oscillation frequency remains equal to or substantially close to a preset frequency.

12. The peak detection unit includes:

12. An aerosol generating device according to any one of claims 1 to 11, comprising a holding capacitor configured to hold a peak voltage of the oscillator.

13. The peak detection unit includes: an operational amplifier located between the holding capacitor and an oscillator, the operational amplifier being further configured to output the oscillator voltage to the holding capacitor; and a voltage follower configured to output a peak voltage of the oscillator held by the holding capacitor.

14. The peak detection unit includes:

14. The aerosol generating device of claim 13, further comprising a discharge switch configured to discharge the holding capacitor when on.

15. a sampling end of the operational amplifier is connected to the oscillator; The aerosol generating device of claim 14, wherein the holding capacitor includes three paths, a first path of which is connected to the output terminal of the operational amplifier, a second path of which is connected to the discharge switch, and a third path of which is connected to the sampling terminal of the voltage follower.

16. a susceptor configured to be penetrated by a varying magnetic field and generate heat to heat the aerosol-generating product; and an oscillator including an induction coil and a capacitor, the oscillator being configured to direct a varying current through the induction coil to drive the induction coil to generate a varying magnetic field, comprising: Detecting a peak voltage of the oscillator; determining an oscillation frequency of the oscillator based on the peak voltage; adjusting an oscillation frequency of the oscillator such that the oscillation frequency remains equal to or substantially close to a preset frequency.

17. a susceptor configured to be penetrated by a varying magnetic field and generate heat to heat the aerosol-generating product; 1. A method of controlling an aerosol generating device comprising: a parallel LC oscillator including an induction coil and a capacitor connected in parallel, the parallel LC oscillator being configured to direct a varying current through the induction coil to drive the induction coil to generate a varying magnetic field, the method comprising: driving the parallel LC oscillator to oscillate using a pulse whose frequency or duty ratio varies gradually; Detecting a peak voltage of the parallel LC oscillator; comparing the peak voltage with a preset threshold voltage, and determining an optimal frequency or an optimal duty ratio of the parallel LC oscillator when the peak voltage is equal to or substantially close to the preset threshold voltage; driving the parallel LC oscillator to oscillate according to the optimum frequency or the optimum duty ratio, and further causing an induction coil to generate a varying magnetic field.

18. A control method as described in claim 17, wherein in the pulse in which the frequency gradually changes, the frequency gradually changes from largest to smallest.

19. a susceptor configured to be penetrated by a varying magnetic field and generate heat to heat the aerosol-generating product; 1. A method of controlling an aerosol generating device comprising: a series LC oscillator or series LCC oscillator including an induction coil and a capacitor connected in series, the series LC oscillator or series LCC oscillator being configured to direct a varying current through the induction coil to drive the induction coil to generate a varying magnetic field, the method comprising: driving said series LC oscillator or series LCC oscillator to oscillate using a pulse having a constant duty ratio of 50% and a gradually varying frequency; Detecting a peak voltage of the series LC oscillator or series LCC oscillator; Calculating a difference between a currently detected peak voltage and a previously detected peak voltage; determining whether the difference value is positive; If the signal is positive, the frequency at which the series LC oscillator or the series LCC oscillator is driven to oscillate is reduced, and if the signal is not positive, the previously detected peak voltage is determined to be a maximum value; determining a resonant frequency of the series LC oscillator or series LCC oscillator based on the maximum value of the peak voltage; driving the series LC oscillator or series LCC oscillator to oscillate in accordance with the resonant frequency, and further causing an induction coil to generate a varying magnetic field.

20. 20. The method of claim 19, wherein in the pulses in which the frequency is gradually changed, the frequency is changed gradually from largest to smallest.

21. The step of reducing the frequency at which the series LC oscillator or the series LCC oscillator is driven to oscillate includes: determining whether the difference value is greater than a predetermined value, and if the difference value is greater than the predetermined value, reducing a frequency at which the series LC oscillator or the series LCC oscillator is driven to oscillate according to a first amplitude; and if the difference value is not greater than the predetermined value, reducing a frequency at which the series LC oscillator or the series LCC oscillator is driven to oscillate according to a second amplitude; 20. The method of claim 19, wherein the first amplitude is greater than the second amplitude.

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