Methods, controllers, devices, and computer programs

Abstract

A method comprising the steps of: driving an induction heater resonant circuit at a specified resonant frequency of the resonant circuit in a heating operation mode, wherein the induction heater comprises a switching circuit and a resonant circuit, and the induction heater is for heating a susceptor; comparing the current flowing through the induction heater during the heating operation mode with a target current; and controlling the trigger for a sampling operation mode at least in part based on the difference between the current flowing through the induction heater and the target current, wherein the specified resonant frequency is updated during the sampling operation mode.

Description

Technical Field

[0001] This specification relates to the induction heating of susceptors. Background

[0002] Many induction heating systems for heating susceptors are known. There is still a need for further development in this field. Summary

[0003] This specification, in a first aspect, describes a method including, in a heating operation mode, driving a resonant circuit of an induction heater at a specified resonant frequency of the resonant circuit, where the induction heater includes a switching circuit and a resonant circuit and is for heating a susceptor; comparing a current flowing through the induction heater during the heating operation mode with a target current; and controlling a trigger for a sampling operation mode based at least in part on a difference between the current flowing through the induction heater and the target current, where the specified resonant frequency is updated during the sampling operation mode. The current flowing through the induction heater may include a current flowing through the resonant circuit or a current induced in the susceptor.

[0004] The step of controlling the trigger for the sampling operation mode may include triggering the sampling mode when the current flowing through the induction heater differs from the target current by more than a threshold amount.

[0005] The step of controlling the trigger for the sampling operation mode may include setting a sampling period based at least in part on a difference between the current flowing through the induction heater and the target current, where the sampling period defines an interval between successive sampling operation modes of the induction heater. This method may include shortening the sampling mode period when the current flowing through the induction heater decreases. Alternatively or in addition, this method may include lengthening the sampling mode period when the current flowing through the induction heater increases.

[0006] Some exemplary embodiments further include the step of entering a heating operation mode upon completion of the sampling operation mode.

[0007] This method may further include the step of controlling a switching circuit to apply pulses to a resonant circuit and generate a pulse response in sampling operation mode.

[0008] This method may further include the steps of identifying the resonant frequency of the pulse response and updating the identified resonant frequency accordingly. Furthermore, the resonant frequency of the pulse response may be identified based on the time interval between zero crossings of the pulse response.

[0009] The method may further include the steps of: identifying the difference between the temperature of the susceptor and a target temperature of the susceptor; and setting a sampling period based at least in part on the difference, wherein the sampling period defines the interval between consecutive sampling operation modes of the induction heater. The method may further include the steps of shortening the sampling period if the difference between the estimated temperature and the target temperature decreases, and / or lengthening the sampling period if the difference between the estimated temperature and the target temperature increases.

[0010] In a further embodiment, this specification describes a controller for an induction heater that heats a susceptor (e.g., a susceptor in an aerosol generating device), the controller comprising: a first output unit that applies a pulse to the resonant circuit of an induction heater in a heating operation mode, the pulse being applied at a specified resonant frequency of the heater, the induction heater comprising a switching circuit and a resonant circuit, the induction heater being for heating a susceptor; and a control module that controls the triggering of a sampling operation mode at least in part based on the difference between the current flowing through the induction heater and a target current, the specified resonant frequency of the induction heater being updated during the sampling operation mode.

[0011] In some embodiments, the control module triggers the sampling operation mode when the current flowing through the induction heater differs from the target current by more than a threshold amount.

[0012] The control module may be configured to set the sampling period based at least in part on the difference between the current flowing through the induction heater and the target current, the sampling period defining the interval between consecutive sampling operation modes of the induction heater.

[0013] The control module may further be configured to identify the difference between the temperature of the susceptor and the target temperature of the susceptor, and to set a sampling period based at least in part on the difference, the sampling period defining the interval between consecutive sampling operation modes of the induction heater.

[0014] In further embodiments, this specification describes an apparatus comprising: a resonant circuit comprising an inductive element and a capacitor, wherein the inductive element is for inductively heating a susceptor (e.g., a susceptor of an aerosol generating device); a drive circuit (e.g., a switching circuit such as an H-bridge circuit) that applies pulses to the resonant circuit of an induction heater in a heating operation mode, wherein the pulses are applied at a specified resonant frequency of the heater; and a processor that controls the triggering of a sampling operation mode at least in part based on the difference between the current flowing through the induction heater and a target current, wherein the specified resonant frequency of the induction heater is updated during the sampling operation mode.

[0015] In some exemplary embodiments, the control module triggers the sampling operation mode when the current flowing through the induction heater differs from the target current by more than a threshold amount.

[0016] The control module may be configured to set the sampling period at least in part on the difference between the current flowing through the induction heater and the target current, the sampling period defining the duration and interval of the continuous sampling operation mode of the induction heater. Alternatively or in addition, the control module may be configured to specify the difference between the temperature of the susceptor and the target temperature of the susceptor, and to set a certain / the sampling period at least in part on the difference, the sampling period defining the interval of the continuous sampling operation mode of the induction heater.

[0017] This specification further describes an aerosol supply device comprising the apparatus described above, with reference to a third embodiment. The aerosol generating device may be configured to receive a removable article containing an aerosol generating material. The aerosol generating material may include an aerosol generating substrate and an aerosol forming material. The removable article may comprise a susceptor structure.

[0018] In another embodiment, an aerosol supply system is provided, comprising an aerosol supply device equipped with the apparatus described above with reference to a third embodiment, and an article containing an aerosol generating material.

[0019] The article may be equipped with a susceptor.

[0020] In another embodiment, a method for generating an aerosol is provided, comprising the steps of preparing the aerosol supply system described above and inserting at least partially the aerosol product into a chamber.

[0021] In further embodiments, this specification describes a computer program that includes instructions causing an apparatus to perform (at least) any of the methods described herein (including the methods of the first embodiment described above).

[0022] This specification further describes, in additional aspects, a computer-readable medium (such as a non-transitory computer-readable medium) that includes program instructions stored for performing (at least) any of the methods described herein (including the method of the first aspect described above).

[0023] This specification further describes, in additional aspects, computer-readable instructions that, when executed by a computer processing device, cause the computer processing device to perform (at least) any of the methods described herein (including the method of the first aspect described above).

[0024] This specification, in another aspect, describes an apparatus comprising at least one processor and at least one memory including computer program code that, when executed by the at least one processor, causes the apparatus to perform (at least) any of the methods described herein (including the method of the first aspect described above).

Brief Description of the Drawings

[0025] Next, exemplary embodiments will be described merely as examples with reference to the following schematic drawings. [Figure 1] It is a configuration diagram of a system according to an exemplary embodiment. [Figure 2] It is a flowchart showing an algorithm according to an exemplary embodiment. [Figure 3] It is a flowchart showing an algorithm according to an exemplary embodiment. [Figure 4] It is a flowchart showing an algorithm according to an exemplary embodiment. [Figure 5] It is a configuration diagram of a circuit according to an exemplary embodiment. [Figure 6] It is a configuration diagram of a circuit according to an exemplary embodiment. [Figure 7] It is a configuration diagram of a system according to an exemplary embodiment. [Figure 8] It is a flowchart showing an algorithm according to an exemplary embodiment. [Figure 9] A graph showing a pulse according to an exemplary embodiment. [Figure 10] A graph showing a pulse response according to an exemplary embodiment. [Figure 11] A flowchart showing an algorithm according to an exemplary embodiment. [Figure 12] A flowchart showing an algorithm according to an exemplary embodiment. [Figure 13] A flowchart showing an algorithm according to an exemplary embodiment. [Figure 14] A flowchart showing an algorithm according to an exemplary embodiment. [Figure 15] A flowchart showing an algorithm according to an exemplary embodiment. [Figure 16] A flowchart showing an algorithm according to an exemplary embodiment. [Figure 17] A flowchart showing an algorithm according to an exemplary embodiment. [Figure 18] A diagram showing a non-combustion aerosol supply system according to an exemplary embodiment. [Figure 19] A diagram of a non-combustion aerosol supply system according to an exemplary embodiment. [Figure 20] A diagram of an article for use with a non-combustion aerosol delivery device according to an exemplary embodiment. [Figure 21] A block diagram of a system according to an exemplary embodiment. Detailed Description

[0026] As used herein, the term "aerosol delivery device" is intended to encompass systems that deliver substances to a user and includes the following. · Non-combustion aerosol supply systems that release compounds from aerosolizable substances without burning the aerosolizable material, such as composite systems that generate an aerosol using an e-cigarette, a tobacco heating product, and a combination of aerosolizable materials, and Articles comprising aerosolizable materials and configured for use in one of these non-combustible aerosol supply systems.

[0027] According to this disclosure, a “combustion” aerosol supply system is a system in which an aerosolizable material, which is a component of the aerosol supply system (or a component of the aerosol supply system), is combusted or ignited in order to facilitate delivery to the user.

[0028] According to this disclosure, a “non-combustible” aerosol supply system is a system in which the aerosolizable material, which is a component of the aerosol supply system (or a component of the aerosol supply system), is not burned or ignited in order to facilitate delivery to the user. In the embodiments described herein, the delivery system is a non-combustible aerosol supply system, such as a powered non-combustible aerosol supply system.

[0029] In one embodiment, the non-combustible aerosol supply system is an e-cigarette, also known as a vaping device or an electronic nicotine delivery system (END), but it should be noted that the presence of nicotine in the aerosolizable material is not essential.

[0030] In one embodiment, the non-combustible aerosol supply system is a tobacco heating system, also known as a non-combustible heating system.

[0031] In one embodiment, the non-combustible aerosol supply system is a composite system that generates an aerosol using a combination of aerosolizable materials, one or more of which may be heated. Each of the aerosolizable materials may be, for example, in the form of a solid, liquid, or gel, and may or may not contain nicotine. In one embodiment, the composite system includes a liquid or gel aerosolizable material and a solid aerosolizable material. The solid aerosolizable material may include, for example, tobacco or a non-tobacco product.

[0032] A non-combustible aerosol supply system may typically comprise a non-combustible aerosol supply device and articles used in conjunction with the non-combustible aerosol supply system. However, articles that themselves include means for supplying power to aerosol generating components may themselves constitute a non-combustible aerosol supply system.

[0033] In one embodiment, the non-combustible aerosol supply device may include a power source and a controller. The power source may be a power source or a heat source. In one embodiment, the heat source includes a carbon substrate which may be energized to supply power in the form of heat to an aerosolizable material or heat transfer material adjacent to the heat source. In one embodiment, the power source, such as the heat source, is provided within an article to form a non-combustible aerosol supply section.

[0034] In one embodiment, an article used with a non-combustible aerosol supply device may comprise an aerosolizable material, an aerosol generating component, an aerosol generating region, a mouthpiece, and / or a region for receiving the aerosolizable material.

[0035] In one embodiment, the aerosol-generating component is a heater capable of interacting with an aerosolizable material to release one or more volatile substances from the aerosolizable material to form an aerosol.

[0036] In one embodiment, the aerosolizable material may comprise an active material, an aerosol-forming material, and optionally one or more functional materials. The active material may comprise nicotine (optionally contained in tobacco or tobacco derivatives) or one or more other non-olfactory physiologically active materials. Non-olfactory physiologically active materials are materials included in the aerosolizable material to realize physiological responses other than olfactory perception. The active substance used herein may be a physiologically active material, which is a material intended to realize or promote a physiological response. The active substance may be selected from, for example, nutritional supplements, nootropics, and psychoactive drugs. The active substance may be naturally occurring or synthetically obtained. The active substance may comprise, for example, nicotine, caffeine, taurine, theine, vitamins such as B6, B12, or C, melatonin, cannabinoids, or components, derivatives, or combinations thereof. The active substance may comprise one or more components, derivatives, or extracts from tobacco, cannabis, or other plant substances. In some embodiments, the active substance includes nicotine. In some embodiments, the active substance includes caffeine, melatonin, or vitamin B12. In one embodiment, the active substance is a legally recognized recreational drug.

[0037] The aerosol-forming material may contain one or more of the following: glycerin, glycerol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,3-butylene glycol, erythritol, meso-erythritol, ethyl vanillate, ethyl laurate, diethyl suberate, triethyl citrate, triacetin, diacetin mixture, benzyl benzoate, benzyl phenylacetate, tributyline, lauryl acetate, lauric acid, myristic acid, and propylene carbonate.

[0038] One or more functional materials may include one or more of the following: fragrances, carriers, pH adjusters, stabilizers, and / or antioxidants.

[0039] In one embodiment, an article used with a non-combustible aerosol supply device may include an aerosolizable material or a region for receiving the aerosolizable material. In one embodiment, an article used with a non-combustible aerosol supply device may include a suction port. The region for receiving the aerosolizable material may be a storage region for storing the aerosolizable material. The storage region may be, for example, a reservoir. In one embodiment, the region for receiving the aerosolizable material may be separate from the aerosol generation region, or may be combined with the aerosol generation region.

[0040] Aerosolizable materials, sometimes referred to herein as aerosol-generating materials, are materials capable of generating aerosols when, for example, heated, irradiated, or electrically energized by other means. Aerosolizable materials may be in the form of solids, liquids, or gels, and may or may not contain nicotine and / or flavorings.

[0041] The aerosol-generating material may be an amorphous solid. In some embodiments, the amorphous solid is a monolithic solid. The aerosol-generating material may be non-fibrous or fibrous. In some embodiments, the aerosol-generating material may be a dry gel. The aerosol-generating material may be a solid material that can hold some fluid, such as a liquid, internally. In some embodiments, the held fluid may be water (such as water absorbed from the surroundings of the aerosol-generating material), or the held fluid may be a solvent (such as when the aerosol-generating material is formed from a suspension). In some embodiments, the solvent may be water.

[0042] The aerosolizable material may be present on a substrate. The substrate may be, for example, paper, paper scraps, cardboard, thick paper, reconstituted aerosolizable material, plastic material, ceramic material, composite material, glass, metal, or alloy, or may contain these.

[0043] Consumables are articles containing or consisting of aerosol-generating materials, some or all of which are intended to be consumed during use by the user. Consumables may also include one or more other components, such as an aerosol-generating material storage area, an aerosol-generating material transfer component, an aerosol-generating area, a housing, packaging material, a mouthpiece, a filter, and / or an aerosol modifier. Consumables may also include an aerosol generator, such as a heater that generates heat to cause the aerosol-generating material to produce an aerosol during use. The heater may include, for example, a combustible material or a material that can be heated by electrical conductivity.

[0044] Figure 1 is a diagram of the system shown as a whole, reference numeral 10, according to an exemplary embodiment. The system 10 comprises a power supply 11 in the form of a direct current (DC) voltage source, a switching component 13, a resonant circuit 14, a susceptor component 16, and a control circuit 18. The switching component 13 and the resonant circuit 14 may be integrally coupled to an induction heating component 12 that can be used to heat the susceptor 16.

[0045] As will be discussed in detail below, the resonant circuit 14 may include one or more capacitors and one or more inductive elements that inductively heat the susceptor structure 16 to heat the aerosol-generating material. By heating the aerosol-generating material, an aerosol may be generated.

[0046] The switching component 13 may enable the generation of alternating current from the DC voltage source 11 (under the control of the control circuit 18). The alternating current may flow through one or more inductive elements and may heat the susceptor component 16. The switching component may include multiple transistors. An exemplary DC-AC converter includes an H-bridge or inverter circuit, the example of which is discussed below.

[0047] A susceptor is a material that can be heated by the intrusion of a fluctuating magnetic field, such as an alternating magnetic field. The heating material may be a conductive material, in which case the intrusion of the fluctuating magnetic field causes induction heating of the heating material and the thermally conductive material. The heating material may also be a magnetic material, in which case the intrusion of the fluctuating magnetic field causes magnetic hysteresis heating of the heating material. The heating material may be both conductive and magnetic, in which case the heating material can be heated by both heating mechanisms.

[0048] Induction heating is the process of heating a conductive object by the penetration of a fluctuating magnetic field into the object. This process is described by Faraday's law of electromagnetic induction and Ohm's law. An induction heater may include an electromagnet and a device that passes a fluctuating current, such as an alternating current, through the electromagnet. When the electromagnet and the object to be heated are in a suitable relative position such that the fluctuating magnetic field generated by the electromagnet penetrates the object, one or more eddy currents are generated inside the object. Objects have resistance to the flow of electric current. Therefore, when such eddy currents are generated inside an object, the flow of eddy currents against the electrical resistance of the object heats the object. This process is called Joule heating, Ohm heating, or resistance heating. An object that can be induced heated is known as a susceptor.

[0049] Magnetic hysteresis heating is a process in which an object made of a magnetic material is heated by the penetration of a fluctuating magnetic field into the object. A magnetic material can be thought of as containing numerous atomic-scale magnets or magnetic dipoles. When a magnetic field is applied to a material, the magnetic dipoles align with the magnetic field. Therefore, when a fluctuating magnetic field, such as an alternating magnetic field generated by an electromagnet, penetrates a magnetic material, the orientation of the magnetic dipoles changes in accordance with the fluctuations in the applied magnetic field. This change in the orientation of the magnetic dipoles generates heat in the magnetic material.

[0050] When an object is both conductive and magnetic, the penetration of a fluctuating magnetic field into the object can cause both Joule heating and magnetic hysteresis heating. Furthermore, the use of magnetic materials can strengthen the magnetic field and enhance Joule heating.

[0051] In each of the above processes, heat is generated within the object itself rather than through an external heat source using heat conduction. Therefore, by selecting particularly suitable object materials and geometry, as well as suitable magnitude and direction of the fluctuating magnetic field relative to the object, rapid temperature rise and more uniform heat distribution can be achieved. Furthermore, induction heating and magnetic hysteresis heating do not require a physical connection between the source of the fluctuating magnetic field and the object, which may result in greater design flexibility and controllability regarding the heating profile, as well as potentially lower costs.

[0052] Figure 2 is a flowchart illustrating an algorithm, collectively referred to as reference numeral 20, according to an exemplary embodiment. Algorithm 20 may be implemented using the system 10 described above.

[0053] Algorithm 20 begins with operation 22 in which a resonant circuit (e.g., resonant circuit 14) is driven at the resonant frequency of the resonant circuit in the heating operation mode. The switching component 13 may be switched (under the control of the control circuit 18) at a specified resonant frequency of the resonant circuit 14, for example. As will be discussed further below, the effectiveness of heating mode 22 may depend on the accuracy of the resonant frequency identification. The effectiveness of heating mode 22 may also depend on the resolution of the output frequency used to drive the resonant circuit.

[0054] In operation 24, the system enters sampling mode. In sampling mode, an attempt may be made to determine the resonant frequency to be used in the heating mode (for example, during the next iteration of algorithm 20). As will be discussed in detail below, sampling mode may include applying pulses to the resonant circuit at specified time intervals and processing the resonant response to determine / estimate the resonant frequency.

[0055] In operation 26, the drive frequency of the resonant circuit is set based on the identified resonant frequency.

[0056] Therefore, the heating mode parameters (including the drive frequency and sampling interval) are set in operation 26. Heating of the susceptor continues in the next iteration of heating mode 22 until the time interval specified by the sampling mode is reached. Algorithm 20 then enters sampling mode 24 again to determine the resonant frequency of the resonant circuit again and updates the heating mode and sampling mode parameters (in operation 26).

[0057] A controller (which may be part of the control circuit 18) may be used to determine how often to initiate the sampling mode 24. The controller may attempt to strike a balance between sampling at a frequency sufficient to ensure that the resonant circuit is driven at the resonant frequency (or near the resonant frequency) in the heating mode 22 (which tends to increase heating efficiency) and having a low sampling rate (i.e., a long sampling period) to use most of the time the susceptor is heated (which also tends to increase heating efficiency).

[0058] The sampling period (i.e., the frequency of entering sampling mode 24) may be a controllable variable. As will be discussed in detail below, there are several mechanisms (e.g., related to heating temperature, heating current, or both) that can be used to set the sampling period.

[0059] Figure 3 is a flowchart illustrating an exemplary embodiment of the algorithm, which is collectively referred to as reference number 30.

[0060] Algorithm 30 begins with operation 32, in which the temperature of the induction heater (e.g., the temperature of the susceptor 16) is identified or estimated. Operation 34 adjusts the sampling period based on the temperature identified in operation 32.

[0061] For example, the temperature identified or estimated in operation 32 may be compared to the target temperature of the susceptor. The sampling period set in operation 34 (which may define the sampling of the induction heater temperature and the duration of the heating operation mode) may be set, at least in part, according to the temperature difference. For example, the sampling period may be shortened as the heater temperature approaches the target temperature so that the sampling mode is performed more frequently when the heater temperature is close to the target temperature.

[0062] Figure 4 is a flowchart illustrating an exemplary embodiment of the algorithm, which is collectively referred to as reference number 40.

[0063] Algorithm 40 begins with operation 42, in which the current flowing through the induction heater (e.g., resonant circuit 14) is determined. Operation 44 adjusts the sampling period based on the current determined in operation 42.

[0064] For example, the current specified in operation 42 may be compared to a target current (or threshold current). The target current may be a current that can be predicted when the resonant circuit is driven at its resonant frequency, or a current close to it. The sampling period set in operation 44 may be set according to the current difference. The sampling period may lengthen as the heater current approaches the target current (which may indicate that the resonant circuit is driven at or near its resonant frequency), for example, so that the sampling mode is not performed too frequently when the resonant circuit is driven near its resonant frequency.

[0065] When the heater current is relatively low, shortening the sampling period can improve the heater's efficiency by resetting the drive frequency more frequently (in operation 26). Conversely, when the heater current is high (e.g., at or near the target current), the sampling period can be lengthened so that the drive frequency is not updated too frequently.

[0066] In some embodiments, both the heater temperature and the current flowing through the heater may be used to set the sampling period (for example, the principles of algorithms 30 and 40 may be combined). For example, algorithms 30 and 40 may be operated in parallel and / or complement each other.

[0067] Figure 5 is a diagram of the circuit shown as a whole, reference numeral 50, according to an exemplary embodiment. The circuit 50 comprises a first switch 51, a second switch 52, a third switch 53, a fourth switch 54, and a resonant circuit 56. The first to fourth switches 51 to 54 may be implemented using transistors, as will be discussed further below.

[0068] The first to fourth switches 51 to 54 form an H-bridge type bridge circuit which may be used to apply pulses to the resonant circuit 56, the first switch 51 and the second switch 52 form a first half-bridge, and the third switch 53 and the fourth switch 54 form a second half-bridge. Thus, the first to fourth switches 54 are exemplary embodiments of the switching configuration 13, and the resonant circuit 56 is an example of the resonant circuit 14.

[0069] The first switch 51 and the second switch 52 form the first rim of the full H-bridge circuit, and the third switch 53 and the fourth switch 54 form the second rim. More specifically, the first switch 51 controls the first power supply (V in Figure 5). DD The first connection point can be selectively connected to the first connection point, the second switch 52 can selectively connect to the first connection point and ground, the third switch 53 can selectively connect to the first power supply and the second connection point, and the fourth switch 54 can selectively connect to the second connection point and ground. The resonant circuit 56 is provided between the first connection point and the second connection point.

[0070] Figure 6 is a diagram of the circuit shown as a whole, according to an exemplary embodiment, and is denoted by reference numeral 60. Circuit 60 is an exemplary embodiment of circuit 50 described above.

[0071] Circuit 60 includes a positive terminal 67 and a negative (ground) terminal 68 (an exemplary embodiment of the DC voltage source 11 of the system 10 described above). Circuit 60 includes a switching component 64 (implementing the switching circuit 13 described above), where the switching circuit 64 includes a bridge circuit (for example, an H-bridge circuit such as an H-bridge circuit of FETs). Switching component 64 includes a first rim 64a and a second rim 64b, where the first rim 64a and the second rim 64b are coupled by a resonant circuit 69 (which implements the resonant circuits 14 and 56 described above). The first rim 64a includes switches 65a and 65b (implementing switches 51 and 52 described above), and the second rim 64b includes switches 65c and 65d (implementing switches 53 and 54 described above). Switches 65a, 65b, 65c, and 65d may be transistors such as field-effect transistors (FETs), and may receive input from a controller such as the control circuit 18 of system 10.

[0072] The resonant circuit 69 comprises a capacitor 66 and an inductor 63, and as a result, the resonant circuit 69 may be an LC resonant circuit (in fact, it may be an RLC resonant circuit). Circuit 60 further shows a susceptor equivalent circuit 62 (for example, representing the susceptor component 16 of the system 10 described above). The susceptor equivalent circuit 62 comprises resistors and inductors that demonstrate the electrical effects of an exemplary susceptor component (such as the susceptor 16). If a susceptor is present, the susceptor component 62 and the inductor 63 may act as a transformer 61. The transformer 61 may generate a fluctuating magnetic field so that the susceptor is heated when the circuit 60 receives power. During the heating operation mode in which the susceptor component 16 is heated by the inductor component (for example, during operation 22 of algorithm 20), the switching component 64 is driven (for example, by the control circuit 18) to alternately couple the first branch and the second branch, respectively, so that an alternating current passes through the resonant circuit 69. The resonant circuit 69 may have a resonant frequency based in part on the susceptor component 16, and the control circuit 18 may be configured to control the switching component 64 to switch at or near the resonant frequency. Driving the switching circuit at or near the resonant frequency helps to increase efficiency and reduces energy lost in the switching element (which would otherwise overheat the switching element). In an example where the article comprising aluminum foil is the object to be heated, the switching component 64 may be driven at a frequency of about 2.5 MHz. However, in other embodiments, the frequency may be, for example, between 500 kHz and 4 MHz, or any other frequency range.

[0073] Figure 7 is a diagram illustrating the configuration of the system, as a whole, shown by reference numeral 70, according to an exemplary embodiment.

[0074] System 70 comprises a pulse generation circuit 72, resonant circuits 74 (such as resonant circuits 14, 56, and 69), a susceptor 76 (such as a susceptor component 16), and a pulse response processor 78. The pulse generation circuit 72 and the pulse response processor 74 may be implemented as part of the control circuit 18 of System 10, or they may be used in the sampling mode 26 of algorithm 20. In fact, the pulse generation circuit 72 and the pulse response processor 74 may collectively form a controller for an induction heater that heats the susceptor according to the principles described herein.

[0075] The pulse generation circuit 72 may be implemented using the switching configurations of circuits 50 and 60 described above to generate pulses (e.g., pulse edges) by switching between a positive voltage source and a negative voltage source. This is not required in all exemplary embodiments; for example, the pulse generation circuit 72 may be implemented using a half-bridge circuit.

[0076] The pulse response processor 78 may identify one or more performance indicators (or characteristics) of the resonant circuit 74 and the susceptor 76 based on the pulse response. For example, the pulse response processor 78 may generate estimates of the temperature of the susceptor 76 and / or the resonant frequency of the resonant circuit.

[0077] Figure 8 is a flowchart illustrating an algorithm, collectively referred to as reference numeral 80, according to an exemplary embodiment. Algorithm 80 illustrates an exemplary use of system 70.

[0078] Algorithm 80 begins with operation 82, in which a pulse is applied to the resonant circuit 74. The pulse is a rising or falling edge generated by the pulse generation circuit 72.

[0079] Figure 9 is a graph showing a pulse 90 according to an exemplary embodiment. The pulse 90 includes a rising pulse edge 92, which is an example of a pulse edge that may be applied in operation 82. The pulse 90 may be generated by a pulse generation circuit 72 (for example, by an H-bridge or half-bridge circuit). The pulse 90 may be applied, for example, during the sampling mode 24 of algorithm 20 (for example, to generate a pulse response used for estimating temperature and / or resonant frequency).

[0080] The pulse 90 may be applied to the resonant circuit 74. Alternatively, in a system comprising multiple inductive elements, the pulse generation circuit 72 may select one of the multiple resonant circuits, each resonant circuit comprising an inductive element and a capacitor for inductive heating of a susceptor, and the applied pulse induces a pulse response between the capacitor and the inductive element of the selected resonant circuit.

[0081] When the pulse edge 92 is applied to the resonant circuit 74, a pulse response is generated.

[0082] Figure 10 is a graph showing an exemplary pulse response that may be generated at the connection point between the capacitor 66 and inductor 63 of the resonant circuit 69 described above in response to a pulse edge 92, collectively referred to as reference no. 100. The pulse response 100 may take the form of a ringing resonance, as shown in Figure 10. The pulse response is the result of charge bouncing between the inductor(s) and capacitor(s) of the resonant circuit. As a result, in some configurations, no heating of the susceptor occurs; that is, the susceptor temperature remains substantially constant (e.g., within ±1°C or ±0.1°C from the temperature before pulse application). As shown in Figure 10, the resonant frequency of the pulse response can be determined using the zero-crossing period 102. Note that in some exemplary embodiments, other measurements may be used, such as the period between consecutive peaks of the ringing response.

[0083] In operation 84 of algorithm 80, the period between zero crossings (e.g., period 102) is identified. Then, in operation 86, an estimate of the temperature is obtained, at least partially based on the period identified in operation 84.

[0084] The temperature of the resonant circuit may be related to the time interval between zero crossings 102. The temperature may be, for example, roughly proportional to that time interval. Once calibrated, the time interval between zero crossings can be used for temperature measurement (e.g., determination of relative temperature) in operation 86 described above. As mentioned above, in variations of operation 84, other time intervals (such as the time interval between consecutive peaks in the ringing response) may be specified, which may be appropriate, for example, when the ringing response has a DC component.

[0085] Figure 11 is a flowchart illustrating an exemplary embodiment of the algorithm, which is collectively referred to as reference number 110.

[0086] Algorithm 110 begins with operation 112, in which one or both of the following are identified or estimated: a temperature measurement (the difference between the temperature of the induction heater and the target temperature of the heater) and a current (e.g., the current flowing through the induction heater, such as the resonant circuit 14). As discussed above, the temperature in question may be the temperature of a susceptor (e.g., the susceptor 16 of the system 10 described above). This temperature may be identified, for example, based on the time interval between zero crossings of the pulse response.

[0087] Operation 114 is a sampling period or sampling frequency, at least in part, based on the output of operation 112. Thus, the sampling period (or sampling frequency) may be based on the difference between the induction heater temperature and the target temperature, the detected current level, or both. The sampling period or sampling frequency defines the interval of the sampling mode (and thus the duration of the heating operation mode of the induction heater). Algorithm 110 is therefore an exemplary embodiment of operation 26 of algorithm 20 described above.

[0088] The operation 114 of algorithm 110 may be carried out in several ways. Figures 12 to 14 show three exemplary embodiments. Note that the exemplary embodiments may include two or more of these embodiments (and may also include further examples not described herein).

[0089] Figure 12 is a flowchart illustrating an algorithm, collectively referred to as reference no. 120, according to an exemplary embodiment. Algorithm 120 begins with operation 122, which determines whether the difference between the estimated heater temperature and the target heater temperature (e.g., identified in operation 112) is decreasing (compared to the previous sample). If it is decreasing, operation 124 of algorithm 120 shortens the sampling period (i.e., increases the sampling frequency). Thus, sampling is performed more frequently as the heater temperature approaches the target temperature.

[0090] Figure 13 is a flowchart illustrating an algorithm, shown collectively as reference no. 130, according to an exemplary embodiment. Algorithm 130 begins with operation 132, which determines whether the difference between the estimated heater temperature and the target heater temperature (e.g., identified in operation 112) is increasing. If it is increasing, operation 134 of algorithm 130 increases the sampling period. Thus, sampling is performed less frequently as the heater temperature moves away from the target temperature. More specifically, sampling may be performed less frequently when the heater temperature is below the target temperature and moving away from the target temperature.

[0091] Algorithms 120 and / or 130 may thus form part of operation 114 of algorithm 110 (or operation 26 of algorithm 20), and as a result, the sampling period may be lengthened or shortened depending on whether the temperature difference identified in operation 112 is increasing or decreasing. In this way, the sampling period shortens as the temperature approaches the target temperature. Of course, algorithms 120 and 130 may be implemented as a single algorithm rather than two separate algorithms.

[0092] By shortening the sampling period as the identified / estimated temperature approaches the target temperature, and lengthening the sampling period as the identified / estimated temperature moves away from the target temperature, the ratio of heating time to sampling time can be increased when the heater temperature is sufficiently lower than the target temperature (thus increasing the proportion of time the susceptor is heated), and the ratio can be decreased when the heater temperature is close to the target temperature (thus improving the accuracy of the heating operation).

[0093] Figure 14 is a flowchart illustrating an algorithm, collectively referred to as reference no. 140, according to an exemplary embodiment. Algorithm 140 begins with operation 142, in which the current flowing through the heater (e.g., specified in operation 112) is specified. As mentioned above, a high heater current indicates that the resonant circuit is being driven at or near the resonant frequency. In operation 144, the sampling mode period is set, at least in part, based on the specified heater current. For example, the sampling mode period may lengthen as the specified heater current increases, and vice versa (thus, sampling is performed at a lower frequency as the heater current increases).

[0094] Algorithm 140 may form part of operation 114 of algorithm 110 (or operation 26 of algorithm 20). Furthermore, algorithms 120, 130, and 140 (or any combination thereof) may form part of operation 114 of algorithm 110 (or operation 26 of algorithm 20).

[0095] Figure 15 is a flowchart illustrating an exemplary embodiment of the algorithm, which is collectively referred to as reference numeral 150. Algorithm 150 has several similarities to algorithm 20 described above.

[0096] Algorithm 150 begins with operation 152 in which the resonant circuit (e.g., resonant circuit 14) is driven at a specified resonant frequency of the resonant circuit in the heating operation mode. The switching component 13 may be switched (under the control of the control circuit 18) at a specified resonant frequency of the resonant circuit 14, for example.

[0097] Operation 154 determines whether or not the sampling mode is triggered. If it is triggered, the algorithm proceeds to operation 156; otherwise, the algorithm returns to operation 152. As discussed in detail elsewhere, whether or not the sampling mode is triggered may depend, at least in part, on the current flowing through the induction heater and / or the temperature of the induction heater.

[0098] In operation 156, the system enters sampling mode. In sampling mode, an attempt may be made to determine the resonant frequency to be used in heating mode 152. As discussed in detail above, sampling mode may include applying pulses to the resonant circuit and processing the resonant response to determine / estimate the resonant frequency (e.g., based on the determined / estimated temperature). The resonant frequency may be determined, for example, based on the time interval between zero crossings in the pulse response. In operation 156, the drive frequency of the resonant circuit is set based on the determined resonant frequency.

[0099] Once the sampling mode is complete (and the drive frequency has been set), algorithm 150 returns to operation 152, where it re-enters the heating operation mode.

[0100] Operation 154 may include determining whether the sampling mode period has ended. If it has ended, algorithm 150 proceeds to operation 156; otherwise, algorithm 150 returns to operation 152. The sampling mode period may be set as described above, for example, with reference to Figures 11 to 14.

[0101] Alternatively, or in addition, operation 154 may include identifying whether certain conditions (other than the end of the sampling mode period) have occurred that would justify triggering the sampling mode. Thus, in some exemplary embodiments, the sampling period may be used for periodic sampling, and in addition, the sampling mode may be triggered when a defined event (such as a threshold being exceeded) occurs.

[0102] Figure 16 is a flowchart illustrating an exemplary embodiment of the algorithm, which is collectively referred to as reference numeral 160. Algorithm 160 is an exemplary embodiment of operation 154 of algorithm 150 described above.

[0103] Operation 162 of algorithm 160 determines whether the current flowing through the heater (e.g., identified in operation 152) is below a threshold level (e.g., indicating that the heater's operating frequency is not close enough to the resonant frequency). If it is, the algorithm proceeds to operation 164, where a sampling mode is triggered. Operation 164 may therefore trigger the sampling mode 156 of algorithm 150 described above.

[0104] Figure 17 is a flowchart illustrating an exemplary embodiment of the algorithm, which is collectively referred to as reference numeral 170. Algorithm 170 is an exemplary embodiment of operation 154 of algorithm 150 described above.

[0105] Algorithm 170 begins with operation 172, which determines whether the sampling period has ended. If it has ended, the algorithm proceeds to operation 176, which triggers a sampling mode (for example, triggering sampling mode 156 of algorithm 150 as described above). If it has not ended, the algorithm proceeds to operation 173.

[0106] Operation 173 determines whether the current flowing through the heater is below a threshold level (for example, indicating that the heater's operating frequency is not close enough to the resonant frequency). If it is, the algorithm proceeds to operation 176, where a sampling mode is triggered (for example, triggering sampling mode 156 of algorithm 150 described above). If it is not below the threshold, the algorithm proceeds to operation 174.

[0107] In operation 174, the difference between the heater temperature and the target heater temperature is determined. In operation 175, as discussed in detail above, the sampling period is set according to the difference determined in operation 174.

[0108] Algorithm 170 thus provides an exemplary embodiment of operation 154 of algorithm 150, which can determine when and how to trigger the sampling mode using both the heater current and the heater temperature.

[0109] Figures 18–20 show a non-combustible aerosol supply system, collectively referred to as reference number 220, according to an exemplary embodiment. The aerosol supply system comprises an aerosol supply device, which is an example of an induction heating device that may be controlled according to the principles described herein.

[0110] Figure 18 is a perspective view of the aerosol supply device 220A with an outer cover. The aerosol supply device 220A may include a replaceable article 221 which may be inserted into the aerosol supply device 220A and (may be provided within article 221, as will be discussed further below) allows heating of the susceptor. The aerosol supply device 220A may further include an activation switch 222 which may be used to switch the aerosol supply device 220A on or off.

[0111] Figure 19 shows the aerosol supply device 220B with its outer cover removed. The aerosol generating device 220B comprises an article 221, an activation switch 222, a plurality of inductive elements 223a, 223b, and 223c, and one or more air tube extenders 224 and 225. The one or more air tube extenders 224 and 225 may be optional. The activation switch 222 may be optional and may be provided with, for example, a pressure trigger or some other on-demand activation configuration.

[0112] Multiple inductors 223a, 223b, and 223c may each form part of a resonant circuit, such as the resonant circuit 14. Inductor 223a may comprise a helical inductor coil. In one example, the helical inductor coil is made from helically wound Litz wire / cable to provide a helical inductor coil. Many alternative inductors can be formed, such as inductors formed within a printed circuit board. Inductors 223b and 223c may be similar to inductor 223a. The use of three inductors 223a, 223b, and 223c is not essential in all exemplary embodiments. The aerosol generating device 220 may therefore comprise one or more inductors.

[0113] The susceptor may be provided as part of article 221. In an exemplary embodiment, when article 221 is inserted into the aerosol generating device 220, the aerosol generating device 220 may be turned on by the insertion of article 221. This may be by detecting the presence of article 221 in the aerosol generating device using a suitable sensor (e.g., a light sensor), or, if the susceptor forms part of article 221, by detecting the presence of the susceptor, for example, using a resonant circuit 14. When the aerosol generating device 220 is turned on, the inductive element 223 may induce heating of article 221 through the susceptor. In an alternative embodiment, the susceptor may be provided as part of the aerosol generating device 220 (e.g., as part of a holder that receives article 221).

[0114] Figure 20 shows an article, collectively referred to as reference number 230, used with a non-combustible aerosol supply device, according to an exemplary embodiment. Article 230 is an example of the interchangeable article 221 described above with reference to Figures 18 and 19.

[0115] Article 230 comprises a mouthpiece 231 and a cylindrical rod of aerosol-generating material 233, which in this case is tobacco material, connected to the mouthpiece 231. The aerosol-generating material 233 provides an aerosol when heated in a non-combustible aerosol-generating device, such as the aerosol-generating device 20 described herein. The aerosol-generating material 233 is wrapped in packaging material 232. The packaging material 232 may be, for example, paper or paper-backed foil packaging material. The packaging material 232 may be substantially airtight.

[0116] In one embodiment, the packaging material 232 includes aluminum foil. The aluminum foil has been found to be particularly effective in promoting aerosol formation within the aerosol-generating material 233. In one example, the aluminum foil has a metal layer about 6 μm thick. The aluminum foil may have a paper backing. However, in alternative configurations, the aluminum foil can have other thicknesses, for example, 4 μm to 16 μm. The aluminum foil also does not need to have a paper backing; it may have a backing made of other materials, for example, which helps to give the foil adequate tensile strength, or it may have no backing material at all. Metal layers or foils other than aluminum can also be used. Furthermore, it is not essential that such a metal layer be provided as part of the article 230; for example, such a metal layer may be provided as part of the apparatus 220.

[0117] The aerosol-generating material 233, also referred to herein as the aerosol-generating substrate 233, comprises at least one aerosol-forming material. In this example, the aerosol-forming material is glycerol. In alternative examples, the aerosol-forming material may be other materials or combinations thereof as described herein. Aerosol-forming materials have been found to improve the sensory performance of articles by facilitating the transfer of compounds, such as fragrance compounds, from the aerosol-generating material to the consumer.

[0118] As shown in Figure 20, the mouthpiece 231 of article 230 comprises an upstream end 231a adjacent to the aerosol-generating substrate 233, and a downstream end 231b distal to the aerosol-generating substrate 233. The aerosol-generating substrate may contain tobacco, but alternatives are also possible.

[0119] The spout 231 in this example includes a body of material 236 located upstream of the hollow tubular element 234, adjacent to and in contact with the hollow tubular element 234 in this example. The body of material 236 and the hollow tubular element 234 each define a substantially cylindrical overall shape and share a common longitudinal axis. The body of material 236 is encased in a first plug wrap 237. The first plug wrap 237 may have a basis weight of less than 50 gsm, such as about 20 gsm to 40 gsm.

[0120] In this example, the hollow tubular element 234 is the first hollow tubular element 234, and the suction port includes a second hollow tubular element 238, also called a cooling element, upstream of the first hollow tubular element 234. In this example, the second hollow tubular element 238 is upstream of the mass of material 236, adjacent to the mass of material, and in contact with the mass of material. The mass of material 236 and the second hollow tubular element 238 each define a substantially cylindrical overall shape and share a common longitudinal axis. The second hollow tubular element 238 is formed from multiple layers of paper that are wound in parallel with their seams butted together to form the tubular element 238. In this example, the first and second layers of paper are provided in the form of a double-layered tube, but in other examples, three, four, or more layers of paper can be used to form a triple-layered, quadruple-layered, or more-layered tube. Other structures can also be used, such as spirally wound layers of paper, cardboard tubes, tubes formed using a coagulant paper type process, molded or extruded plastic tubes, or similar. The second hollow tubular element 238 may also be formed using rigid plug wrap and / or chip paper, such as the second plug wrap 239 and / or chip paper 235 described herein, which means that a separate tubular element is not required.

[0121] The second hollow tubular element 238 is positioned around the inlet 231, which acts as a cooling section, and defines a void within the inlet. The void provides a chamber through which heated and volatile components generated by the aerosol-generating material 233 may flow. The second hollow tubular element 238 is hollow to provide a chamber for aerosol accumulation, but is stiff enough to withstand axial compressive forces and bending moments that may occur during manufacturing and while using the article 221. The second hollow tubular element 238 introduces a physical displacement between the aerosol-generating material 33 and the mass of material 36. The physical displacement introduced by the second hollow tubular element 238 results in a temperature gradient along the entire length of the second hollow tubular element 238.

[0122] Of course, article 230 is presented merely as an example. Those skilled in the art will recognize many alternative components of such article that can be used in the systems described herein. Similarly, those skilled in the art will recognize other articles that may be heated using the principles described herein.

[0123] Figure 21 is a diagram of the system shown as a whole, reference numeral 210, according to an exemplary embodiment. System 210 may be used to implement one or more of the algorithms described above.

[0124] The system 210 comprises a processor 212 and memory 214 (e.g., RAM or RAM), and may also include an input or output unit 216. The processor 212 may be used to implement one or more of the algorithms described above, for example, based on computer program code stored in memory 214.

[0125] The various embodiments described herein are presented solely to aid in the understanding and teaching of the features described in the claims. These embodiments are provided merely as representative examples of embodiments and are not exhaustive and / or exclusive. The advantages, embodiments, examples, functions, features, structures, and / or other aspects described herein should not be construed as limitations on the scope of the invention as defined by the claims, or limitations on equivalents of the claims, and it should be understood that other embodiments may be used and modified without departing from the scope of the invention as described in the claims. Various embodiments of the invention may preferably include, consist of, or substantially consist of, appropriate combinations of disclosed elements, components, features, parts, steps, means, etc., other than those specifically described herein. This disclosure may also include other inventions that are not currently claimed but may be claimed in the future.

Claims

1. In the heating operation mode, the step of driving the resonant circuit of an induction heater at a specified resonant frequency of the resonant circuit, wherein the induction heater comprises a switching circuit and a resonant circuit, and the induction heater is for heating a susceptor; The steps include comparing the current flowing through the induction heater during the heating operation mode with a target current, A step of controlling the trigger of a sampling operation mode, at least in part, based on the difference between the current flowing through the induction heater and the target current, wherein the identified resonant frequency is updated during the sampling operation mode. Methods that include...

2. The method according to claim 1, wherein the current flowing through the induction heater includes the current flowing through the resonant circuit.

3. The method according to claim 1, wherein the current flowing through the induction heater includes a current induced in the susceptor.

4. The method according to any one of claims 1 to 3, wherein the step of controlling the trigger of the sampling operation mode includes triggering the sampling operation mode when the current flowing through the induction heater differs from the target current by more than a threshold amount.

5. The method according to any one of claims 1 to 4, wherein the step of controlling the trigger of the sampling operation mode includes setting a sampling period based at least in part on the difference between the current flowing through the induction heater and the target current, the sampling period defining the interval between consecutive sampling operation modes of the induction heater.

6. If the current flowing through the induction heater decreases, shorten the sampling mode period, and / or If the current flowing through the induction heater increases, the sampling mode period is lengthened. The method according to claim 5, further comprising:

7. Step to enter the heating operation mode upon completion of the sampling operation mode. The method according to any one of claims 1 to 6, further comprising:

8. In the sampling operation mode, the switching circuit is controlled to apply a pulse to the resonant circuit and generate a pulse response. The method according to any one of claims 1 to 7, further comprising:

9. A step of identifying the resonant frequency of the pulse response, and a step of updating the identified resonant frequency accordingly. The method according to any one of claims 1 to 8, further comprising:

10. The method according to claim 9, wherein the resonant frequency of the pulse response is determined based on the time interval between zero crossings of the pulse response.

11. Steps include: identifying the difference between the temperature of the susceptor and the target temperature of the susceptor; and setting a sampling period based at least in part on the difference, wherein the sampling period defines the interval between consecutive sampling operation modes of the induction heater. The method according to any one of claims 1 to 10, further comprising:

12. The method according to claim 11, further comprising the steps of shortening the sampling period when the difference between the estimated temperature and the target temperature decreases, and / or lengthening the sampling period when the difference between the estimated temperature and the target temperature increases.

13. A controller for an induction heater that heats a susceptor, In the heating operation mode, the first output unit applies a pulse to the resonant circuit of the induction heater, the pulse is applied at a specified resonant frequency of the induction heater, the induction heater comprises a switching circuit and a resonant circuit, and the induction heater is for heating a susceptor. A control module that controls the trigger of a sampling operation mode based at least partially on the difference between the current flowing through the induction heater and a target current, wherein the specified resonant frequency of the induction heater is updated during the sampling operation mode, and A controller equipped with the following features.

14. The controller according to claim 13, wherein the control module triggers the sampling operation mode when the current flowing through the induction heater differs from the target current by more than a threshold amount.

15. The controller according to claim 13 or 14, wherein the control module is configured to set a sampling period based at least in part on the difference between the current flowing through the induction heater and the target current, and the sampling period defines the interval between consecutive sampling operation modes of the induction heater.

16. The controller according to any one of claims 13 to 15, wherein the control module is further configured to identify the difference between the temperature of the susceptor and a target temperature of the susceptor, and to set a sampling period at least in part based on the difference, the sampling period defining the interval between consecutive sampling operation modes of the induction heater.

17. The controller according to any one of claims 13 to 16, wherein the susceptor is a susceptor of an aerosol generating device.

18. A resonant circuit comprising an inductive element and a capacitor, wherein the inductive element is for inductively heating a susceptor, In a heating operation mode, a drive circuit applies pulses to the resonant circuit of the induction heater, wherein the pulses are applied at a specified resonant frequency of the induction heater. A processor that controls the trigger of a sampling operation mode based at least partially on the difference between the current flowing through the induction heater and a target current, wherein the specified resonant frequency of the induction heater is updated during the sampling operation mode, and A device that is equipped with the following.

19. The apparatus according to claim 18, wherein the control module triggers the sampling operation mode when the current flowing through the induction heater differs from the target current by more than a threshold amount.

20. The apparatus according to claim 18 or 19, wherein the control module is configured to set the sampling period based at least in part on the difference between the current flowing through the induction heater and the target current, and the sampling period defines the duration and interval of a continuous sampling operation mode of the induction heater.

21. The apparatus according to any one of claims 18 to 20, wherein the control module is further configured to identify the difference between the temperature of the susceptor and a target temperature of the susceptor, and to set a sampling period at least in part based on the difference, the sampling period defining the interval between consecutive sampling operation modes of the induction heater.

22. The apparatus according to any one of claims 18 to 21, wherein the drive circuit is an H-bridge circuit.

23. An aerosol supply device comprising the apparatus described in any one of claims 18 to 22.

24. An aerosol supply system comprising the aerosol supply device described in claim 23 and an article containing an aerosol generating material.

25. A computer program including instructions, wherein the instructions provide at least one instruction to a device. In the heating operation mode, the resonant circuit of the induction heater is driven at a specified resonant frequency of the resonant circuit, wherein the induction heater comprises a switching circuit and a resonant circuit, and the induction heater is for heating a susceptor. The current flowing through the induction heater during the heating operation mode is compared with a target current, and The trigger for the sampling operation mode is controlled at least partially based on the difference between the current flowing through the induction heater and the target current, and the identified resonant frequency is updated during the sampling operation mode. A computer program that executes something.

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