Apparatus for an aerosol provision device

Abstract

An apparatus (2) for an aerosol provision device including a central controller (4) and a plurality of induction units (7a-c). Each of the plurality of induction units (7a-c) includes a resonant circuit (6a-c) including an inductive element (8a-c), which is configured to inductively heat a susceptor, a capacitive element (10a-c) and a local controller (12a-c). The local controller (12a-c) is configured to receive one or more commands from the central controller (4), perform at least one action based on the one or more commands received from the central controller (4) and send feedback to the central controller (4).

Description

[0001] Apparatus for an aerosol provision device

[0002] Technical Field

[0003] The present invention relates to an apparatus for an aerosol provision device and method of operation. The present invention also relates to an aerosol provision device, an aerosol provision system, and a method of generating an aerosol.

[0004] Background

[0005] Smoking articles such as cigarettes, cigars and the like burn tobacco during use to create tobacco smoke. Attempts have been made to provide alternatives to these articles by creating products that release compounds without combusting.

[0006] Examples of such products are so-called “heat not burn” products or tobacco heating devices or products, which release compounds by heating, but not burning, material. The material may be, for example, tobacco or other non-tobacco products, which may or may not contain nicotine.

[0007] Aerosol provision systems, which cover the aforementioned devices or products, are known. Common systems use heaters to create an aerosol from a suitable medium which is then inhaled by a user. Often the medium used needs to be replaced or changed to provide a different aerosol for inhalation. It is known to use inductive heating systems as heaters to create an aerosol from a suitable medium. Induction heating systems generally comprise a magnetic field generating device for generating a varying magnetic field, and a susceptor or heating material which is heatable by penetration with the varying magnetic field to heat the suitable medium.

[0008] Summary

[0009] According to an aspect there is provided an apparatus for an aerosol provision device comprising: a central controller; and a plurality of resonant circuits. Each of the plurality of resonant circuits comprises: an inductive element, wherein the inductive element is configured to inductively heat a susceptor; a capacitive element. Each of the plurality of resonant circuits is provided with a local controller. Each local controller is configured to: receive one or more commands from the central controller; perform at least one action based on the command received from the central controller; and send feedback to the central controller.

[0010] The central controller may be configured to send one or more commands to the local controllers relating to operation of the apparatus.

[0011] The central controller may be configured to send one or more commands to the local controllers relating to one or more of the following: turning power on; turning power off, set power level to be applied through the resonant circuit, set a duration of on time

[0012] The central controller may be configured to send a command including an instruction to apply a pulse to a respective resonant circuit. Each local controller may be configured to: receive the command from the central controller apply a pulse to the resonant circuit; receive feedback from the resonant circuit; and send said feedback to the central controller based on the feedback from the resonant circuit.

[0013] The pulse may be applied to a resonant circuit in a heating mode of operation.

[0014] An edge of applied pulse may induce a pulse response between the capacitive element and the inductive element of the resonant circuit. The pulse response may have a resonant frequency.

[0015] The feedback received by the local controller may be an estimation of the resonant frequency of the resonant circuit.

[0016] The feedback received by the local controller may be an estimation of: a voltage, a power, a resistance, a (resonant) frequency, a temperature and / or timing information relating to any of the elements of the resonant circuit.

[0017] The feedback received by the local controller may be indicative of the response of the resonant circuit to an applied pulse. The feedback received by the local controller may be indicative of the response of the resonant circuit to a pulse that has been applied to the resonant circuit by the local controller in response to a command from the central controller. The feedback indicative of the response of the resonant circuit an applied pulse may be the amplitude of the current and / or the estimated resonant frequency of the resonant circuit.

[0018] The feedback received by the local controller may be a measurement of the current flowing in the resonant circuit.

[0019] The feedback received by the local controller may be a measurement of: a voltage, a power, a resistance, a (resonant) frequency, a temperature and / or timing information relating to any of the elements of the resonant circuit.

[0020] Each of the plurality of resonant circuits may further comprise a bridge circuit configured to connect the inductive element and the capacitive element to the local controller.

[0021] The apparatus further may further comprise a power source. The power source may be configured to provide power to the central controller and each of the plurality of local controllers.

[0022] Each of the plurality of local controllers may be configured to process the feedback that is received from the resonant circuit. The central controller may be configured to process the feedback that is received from the resonant circuit. Each of the plurality of local and the central controller may both be configured to process the feedback that is received from the resonant circuit

[0023] Each of the plurality of induction units may further comprise a frequency estimation circuit. The frequency estimation circuit may be configured to: estimate the resonant frequency of the resonant circuit; and provide feedback to the local controller.

[0024] The central controller may be configured to compare the estimated frequency with a target frequency; and control triggering of a sampling mode of operation based, at least in part, on a difference between the estimated frequency and the target frequency, wherein the estimated resonant frequency is updated during the sampling mode of operation. Each of the plurality of induction units may further comprise a current feedback circuit. The frequency estimation circuit may be configured to: measure the current flowing through the resonant circuit; and provide feedback to the local controller.

[0025] The central controller may be configured to compare the estimated current with a target current; and control triggering of a sampling mode of operation based, at least in part, on a difference between the estimated current and the target current, wherein the determined resonant frequency is updated during the sampling mode of operation.

[0026] Controlling triggering of said sampling mode of operation may comprise triggering said sampling mode in the event that the estimated current differs from the target current by more than a threshold amount.

[0027] Controlling triggering of said sampling mode of operation may comprise setting a sampling period based, at least in part, on the difference between the estimated and the target current, wherein the sampling period defines an interval between successive sampling modes of operation of the inductive element.

[0028] Controlling triggering of said sampling mode of operation may comprise decreasing the sampling mode period if the estimated current flowing in the inductive heater is reduced. The method may further comprise increasing the sampling mode period if the estimated current flowing in the inductive heater is increased.

[0029] The apparatus may comprise any number of resonant circuits. The apparatus may comprise between four and twelve resonant circuits. The apparatus may comprise ten resonant circuits.

[0030] The central controller may be configured to send control signals to each local controller in order to operate each inductive element.

[0031] The central controller may interact with each local controller independently. The central controller may interact with two or more local controllers simultaneously. The central controller may interact with all local controllers simultaneously. According to another aspect there is provided an aerosol provision device comprising the apparatus as described above.

[0032] The aerosol provision device may comprise a heating chamber for removably receiving an article comprising an aerosol generating material.

[0033] The inductive elements of the plurality of resonant circuits may be arranged along a side wall of the heating chamber. The aerosol provision device may comprise at least four inductive elements arranged along a side wall of the heating chamber. The aerosol provision device may comprise at least five inductive elements arranged along a side wall of the heating chamber. The aerosol provision device may comprise at a grid arrangement of inductive elements arranged along a side wall of the heating chamber, for example a 2x4 grid or a 2x5 grid.

[0034] The inductive elements of the plurality of resonant circuits may be arranged along two side walls of the heating chamber. The inductive elements of the plurality of resonant circuits may be arranged along two opposite side walls of the heating chamber. The inductive elements may be arranged in two arrays, each array comprising at least four inductive elements. The inductive elements may be arranged in two arrays, each array comprising at five inductive elements.

[0035] The inductive elements may be planar coils. The inductive elements may be planar spiral inductor coils. The inductive elements may be planar non-spiral inductor coils. The inductor coil may be substantially square. The inductor coil may be substantially rectangular. The inductor coil may be trapezoidal.

[0036] The inductive elements may be disposed on a printable circuit board (PCB).

[0037] The aerosol provision device may comprise a susceptor provided within the heating chamber. The aerosol provision device may comprise two or more susceptors. The aerosol provision device may comprise a plurality of susceptors, each susceptor associated with a respective inductive element.

[0038] The inductive elements may be helical inductor coils, which surround the heating chamber. The aerosol provision device may comprise a power source. The power source may be aligned along a longitudinal axis of the heating chamber. The power source may be aligned along a second longitudinal axis, parallel to the longitudinal axis of the heating chamber.

[0039] The aerosol provision device may comprise a hinged door or removable part of an outer housing to permit access to the chamber such that a user may insert and / or remove an aerosol generating article. The aerosol provision device may be configured for wireless charging.

[0040] According to another aspect there is provided an aerosol provision system comprising the aerosol provision device as described above, and an article comprising an aerosol generating material.

[0041] The aerosol provision device may comprise a susceptor provided within the chamber. The aerosol provision device may comprise two or more susceptors.

[0042] The article may be a cylindrical or rod shape.

[0043] The article may be substantially flat. The article may comprise a carrier component. The carrier component may comprise aerosol generating material provided on the carrier component. The aerosol generating material may be provided as a continuous layer of aerosol generating material. The aerosol generating material may be provided as a plurality of discrete portions of aerosol generating material.

[0044] The carrier component may comprise a heating layer. The carrier component may comprise a heating layer and a support layer.

[0045] The article may comprise one or more susceptor elements.

[0046] The article may comprise a single susceptor element. The single susceptor element may comprise a plurality of susceptor portions. The plurality of susceptor portions may align with a plurality of inductive heating elements provided in the aerosol provision device, when the article is inserted into the device. The article may provide a plurality of susceptors. The plurality of susceptors may align with a plurality of inductive heating elements provided in the aerosol provision device, when the article is inserted into the device.

[0047] The aerosol provision system may further comprise a charging unit having a cavity for removably receiving the aerosol provision device.

[0048] According to another aspect there is provided a method of generating aerosol comprising: providing an aerosol provision system as described above, and at least partially inserting the aerosol generating article into the chamber.

[0049] According to another aspect there is provided a method for controlling an apparatus for an aerosol provision device comprising a plurality of induction units, each induction unit comprising a local controller and a resonant circuit, the method comprising: amending one or more commands from a central controller to at least one of the plurality of local controllers; b) performing, by at least one of the plurality of local controllers, at least one action based on the one or more commands received from the central controller; and c) sending feedback from at least one of the plurality of local controllers to the central controller.

[0050] Step a) may comprise sending one or more commands to the plurality of local controllers relating to operation of the apparatus.

[0051] Step a) may comprise sending one or more commands to the plurality of local controllers relating to one or more of the following: turning power on; turning power off, set power level to be applied through the resonant circuit, set a duration of on time.

[0052] Step a) may comprise applying a pulse to the resonant circuit; and receiving feedback from the resonant circuit. In step c) the feedback sent to the central controller may be based on the feedback from the resonant circuit.

[0053] The feedback received by the local controller may be an estimation of the resonant frequency of the resonant circuit. The feedback received by the local controller may be a measurement of the current flowing in the resonant circuit The method may further comprise estimating the resonant frequency of the resonant circuit; and provide feedback to the local controller. The estimation may be carried out by a frequency estimation circuit provided in the induction unit.

[0054] The method may further comprise comparing the estimated frequency with a target frequency; and control triggering of a sampling mode of operation based, at least in part, on a difference between the estimated frequency and the target frequency, wherein the determined resonant frequency is updated during the sampling mode of operation.

[0055] The method may further comprise measuring the current flowing through the resonant circuit; and provide feedback to the local controller. The measurement may be carried out by a current feedback circuit provided in the induction unit.

[0056] The method may further comprise comparing the measured current with a target current; and control triggering of a sampling mode of operation based, at least in part, on a difference between the measured current and the target current, wherein the determined resonant frequency is updated during the sampling mode of operation.

[0057] Controlling triggering of said sampling mode of operation may comprise triggering said sampling mode in the event that the measured current differs from the target current by more than a threshold amount.

[0058] Controlling triggering of said sampling mode of operation may comprise setting a sampling period based, at least in part, on the difference between the measured and the target current, wherein the sampling period defines an interval between successive sampling modes of operation of the inductive element.

[0059] The method may further comprise decreasing the sampling mode period if the measured current flowing in the inductive heater is reduced. The method may further comprise increasing the sampling mode period if the measured current flowing in the inductive heater is increased. According to a further aspect there is provided a computer program comprising instructions for causing an apparatus for an aerosol provision device comprising a plurality of induction units, each induction unit comprising a resonant circuit and a local controller, to perform at least the following: sending one or more commands from a central controller to at least one of a plurality of local controllers, wherein each local controller is associated with a respective resonant circuit; performing, by at least one of the plurality of local controllers, at least one action based on the one or more commands received from the central controller; and sending feedback from at least one of the plurality of local controllers to the central controller.

[0060] The action performed by the local controller may comprise: applying a pulse to the resonant circuit; receiving feedback from the resonant circuit; and the feedback sent to the central controller is based on the feedback from the resonant circuit.

[0061] Brief Description of the Drawings

[0062] Various embodiments will now be described, by way of example only, and with reference to the accompanying drawings, in which:

[0063] Figure 1 shows a schematic view of an apparatus for an aerosol provision device; Figure 2 shows a flow chart of a method for controlling a system comprising a plurality of induction units for an aerosol provision device;

[0064] Figures 3a and 3b are flows chart outlining methods of operation of the apparatus of figure 1;

[0065] Figures 4a and 4b are plots showing a pulse a pulse response in accordance with example embodiments;

[0066] Figures 5a and 5b are schematic views of a non-combustible aerosol provision system;

[0067] Figure 5c is a cross-sectional view of an article comprising aerosol generating material of the aerosol provision system of Figure 5a;

[0068] Figure 6a shows a schematic view of another non-combustible aerosol provision system;

[0069] Figure 6b shows a schematic view of an article comprising aerosol generating material of the aerosol provision system of Figure 6a; Figure 7a shows an isometric exploded view of another aerosol provision device;

[0070] Figure 7b shows a schematic view of an article comprising aerosol generating material for use in the aerosol provision system of Figure 6a;

[0071] Figure 8a shows a schematic view of another non-combustible aerosol provision system; and

[0072] Figures 8b to 8e show cross-sectional views articles comprising aerosol generating material for use in the aerosol provision system of Figure 8a.

[0073] Detailed Description

[0074] As used herein, the term “delivery mechanism” is intended to encompass systems that deliver a substance to a user, and includes: non-combustible aerosol provision systems that release compounds from an aerosolisable material without combusting the aerosolisable material, such as electronic cigarettes, tobacco heating products, and hybrid systems to generate aerosol using a combination of aerosolisable materials; and articles comprising aerosolisable material and configured to be used in one of these non-combustible aerosol provision systems.

[0075] According to the present disclosure, a “non-combustible” aerosol provision system is one where a constituent aerosol-generating material of the aerosol provision system (or component thereof) is not combusted or burned in order to facilitate delivery of at least one substance to a user.

[0076] In some embodiments, the delivery system is a non-combustible aerosol provision system, such as a powered non-combustible aerosol provision system.

[0077] In some embodiments, the non-combustible aerosol provision system is an electronic cigarette, also known as a vaping device or electronic nicotine delivery system (END), although it is noted that the presence of nicotine in the aerosolgenerating material is not a requirement.

[0078] In some embodiments, the non-combustible aerosol provision system is an aerosolgenerating material heating system, also known as a heat-not-burn system. An example of such a system is a tobacco heating system. In some embodiments, the non-combustible aerosol provision system is a hybrid system to generate aerosol using a combination of aerosol-generating materials, one or a plurality of which may be heated. Each of the aerosol-generating materials may be, for example, in the form of a solid, liquid or gel and may or may not contain nicotine. In some embodiments, the hybrid system comprises a liquid or gel aerosol-generating material and a solid aerosol-generating material. The solid aerosol-generating material may comprise, for example, tobacco or a non-tobacco product.

[0079] Typically, the non-combustible aerosol provision system may comprise a noncombustible aerosol provision device and a consumable for use with the non- combustible aerosol provision device.

[0080] In some embodiments, the disclosure relates to consumables comprising aerosolgenerating material and configured to be used with non-combustible aerosol provision devices. These consumables are sometimes referred to as articles throughout the disclosure.

[0081] In some embodiments, the non-combustible aerosol provision system, such as a non-combustible aerosol provision device thereof, may comprise a power source and a controller. The power source may, for example, be an electric power source.

[0082] In some embodiments, the non-combustible aerosol provision system may comprise an area for receiving the consumable, an aerosol generator, an aerosol generation area, a housing, a mouthpiece, a filter and / or an aerosol-modifying agent.

[0083] In some embodiments, the consumable for use with the non-combustible aerosol provision device may comprise aerosol-generating material, an aerosol-generating material storage area, an aerosol-generating material transfer component, an aerosol generator, an aerosol generation area, a housing, a wrapper, a filter, a mouthpiece, and / or an aerosol-modifying agent.

[0084] As used herein, the term “aerosol-generating material” (which is sometimes referred to herein as an aerosolisable material) is a material that is capable of generating aerosol, for example when heated, irradiated or energized in any other way. Aerosol-generating material may, for example, be in the form of a solid, liquid or semi-solid (such as a gel) which may or may not contain an active substance and / or flavourants.

[0085] In some embodiments, the substance to be delivered comprises an active substance (sometimes referred to herein as an active compound).

[0086] The aerosol-generating material may comprise one or more active substances and / or flavours, one or more aerosol-former materials, and optionally one or more other functional material.

[0087] The aerosol-generating material may comprise a binder, such as a gelling agent, and an aerosol former. Optionally, a substance to be delivered and / or filler may also be present. Optionally, a solvent, such as water, is also present and one or more other components of the aerosol-generating material may or may not be soluble in the solvent. In some embodiments, the aerosol-generating material is substantially free from botanical material. In particular, in some embodiments, the aerosol-generating material is substantially tobacco free.

[0088] The aerosol-generating material may comprise or be in the form of an aerosolgenerating film. The aerosol-generating film may comprise a binder, such as a gelling agent, and an aerosol former. Optionally, a substance to be delivered and / or filler may also be present. The aerosol-generating film may be substantially free from botanical material. In particular, in some embodiments, the aerosolgenerating material is substantially tobacco free.

[0089] The aerosol-generating film may have a thickness of about 0.015 mm to about 1 mm. For example, the thickness may be in the range of about 0.05 mm, 0.1 mm or 0.15 mm to about 0.5 mm or 0.3 mm.

[0090] The aerosol-generating film may be continuous. For example, the film may comprise or be a continuous sheet of material. The aerosol-generating film may be discontinuous. For example, the aerosol-generating film may comprise one or more discrete portions or regions of aerosol-generating material, such as dots, stripes or lines, which may be supported on a support. In such embodiments, the support may be planar or non-planar.

[0091] The aerosol-generating film may be formed by combining a binder, such as a gelling agent, with a solvent, such as water, an aerosol-former and one or more other components, such as one or more substances to be delivered, to form a slurry and then heating the slurry to volatilise at least some of the solvent to form the aerosol-generating film. The slurry may be heated to remove at least about 60 wt%, 70 wt%, 80 wt%, 85 wt% or 90 wt% of the solvent.

[0092] 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 aerosolgenerating material may be a dried gel. The aerosol-generating material may be a solid material that may retain some fluid, such as liquid, within it. In some embodiments the retained fluid may be water (such as water absorbed from the surroundings of the aerosol-generating material) or the retained fluid may be solvent (such as when the aerosol-generating material is formed from a slurry). In some embodiments, the solvent may be water.

[0093] The aerosol-former material may comprise one or more constituents capable of forming an aerosol. In some embodiments, the aerosol-former material may comprise one or more of glycerine, glycerol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,3-butylene glycol, erythritol, meso- Erythritol, ethyl vanillate, ethyl laurate, a diethyl suberate, triethyl citrate, triacetin, a diacetin mixture, benzyl benzoate, benzyl phenyl acetate, tributyrin, lauryl acetate, lauric acid, myristic acid, and propylene carbonate.

[0094] The one or more other functional materials may comprise one or more of pH regulators, colouring agents, preservatives, binders, fillers, stabilizers, and / or antioxidants.

[0095] The material may be present on or in a support, to form a substrate. The support may, for example, be or comprise paper, card, paperboard, cardboard, reconstituted material, a plastics material, a ceramic material, a composite material, glass, a metal, or a metal alloy.

[0096] An aerosol provision device can receive an article comprising aerosol generating material for heating. An “article” in this context is a component that includes or contains in use the aerosol generating material, which is heated to volatilise the aerosol generating material, and optionally other components in use. A user may insert the article into or onto the aerosol provision device before it is heated to produce an aerosol, which the user subsequently inhales.

[0097] An aerosol generator is an apparatus configured to cause aerosol to be generated from the aerosol-generating material. In some embodiments, the aerosol generator is a heater configured to subject the aerosol-generating material to heat energy, so as to release one or more volatiles from the aerosol-generating material to form an aerosol. In inductive heating systems, the aerosol generator comprises a magnetic field generator, such as an inductive element and a susceptor.

[0098] A susceptor is material that is heatable by penetration with a varying magnetic field, such as an alternating magnetic field. The heating material may be an electrically- conductive material, so that penetration thereof with a varying magnetic field causes induction heating of the heating material. The heating material may be magnetic material, so that penetration thereof with a varying magnetic field causes magnetic hysteresis heating of the heating material. The heating material may be both electrically-conductive and magnetic, so that the heating material is heatable by both heating mechanisms.

[0099] A consumable is an article comprising or consisting of aerosol-generating material, part or all of which is intended to be consumed during use by a user. A consumable may comprise one or more other components, such as an aerosolgenerating material storage area, an aerosol-generating material transfer component, an aerosol generation area, a housing, a wrapper, a mouthpiece, a filter and / or an aerosol-modifying agent. A consumable may also comprise an aerosol generator, such as a heater, that emits heat to cause the aerosol- generating material to generate aerosol in use. The heater may, for example, comprise a material heatable by electrical conduction.

[0100] Non-combustible aerosol provision systems may comprise a modular assembly including both a reusable aerosol provision device and a replaceable aerosol generating article. In some implementations, the non-combustible aerosol provision device may comprise a power source and a controller (or control circuitry). The power source may, for example, comprise an electric power source, such as a battery or rechargeable battery. In some implementations, the non-combustible aerosol provision device may also comprise an aerosol generating component. However, in other implementations the aerosol generating article may comprise partially, or entirely, the aerosol generating component.

[0101] Figure 1 shows an apparatus 2 of the present disclosure. In this example, the apparatus includes a central controller 4 and a number of induction units 7a-c. It will be understood that although three induction units 7a-c are shown in Figure 1 , an apparatus 2 of the present disclosure may include any number of induction units 7a-c.

[0102] In the example shown in Figure 1 , each of the induction units 7a-c comprises a resonant circuits 6a-c which include an inductive element 8a-c, a capacitive element 10a-c. Each induction units is provided with a local controller 12a-c.

[0103] In each of the resonant circuits 6a-c, the inductive element 8a-c is directly connected to the corresponding capacitive element 10a-c. The inductive element 8a-c and the corresponding capacitive element 10a-c form a resonant circuit that is configured to inductively heat a susceptor (not shown).

[0104] The inductive element 8a-c and the capacitive element 10a-c of each resonant circuit 6a-c are connected to the corresponding local controller 12a-c through a bridge circuit 14 (only one is shown for clarity). The bridge circuit 14 may include any bridge circuit that is known in the art. In some examples, the bridge circuit 14 includes a half bridge circuit or a full bridge circuit. Each resonant circuit 6a-c, respective local controller 12a-c and bridge circuit 14 can be considered to form an induction unit 7a-7c. Each local controller 12a-c is configured to independently control an induction unit 7a-c.

[0105] The central controller 4 and each of the local controllers 12a-c are further connected to a power source 16. In the example shown in Figure 1 , the local controllers 12a-c are connected to the power source 16 at a first output 18a of the power source 16. The central controller 4 is connected to the power source 16 at a second output 18a of the power source 16.

[0106] Each of the local controllers 12a-c are further connected to the central controller 4. The local controllers 12a-c may be connected to the central controller 4 in any manner known in the art. For example, the connection may be wired or wireless.

[0107] The central controller 4 is configured to send commands to each of the local controllers 12a-c. The commands may be any type of command (e.g. containing any information that is desired).

[0108] Each of the local controllers 6a-c are configured receive said commands from the central controller 4. In other words, each local controller 12a-c receives data from and transmits data to the central controller 4. The data transfer is represented by line 24 in Figure 1.

[0109] The local controllers 12a-c are configured to perform an action based on the command(s) received from the central controller 4.

[0110] It will be understood that the command may related to a variety of operational parameters. For example, the command may include one or more of the following: turn off, set power level to be applied through the resonant circuit, set a duration of on time.

[0111] In some examples, the command includes an instruction to turn the resonant circuit 6a-c on or off, in other words to activate the resonant circuit in a heating mode in order to inductively heat a susceptor. In some examples, the command includes an instruction to apply a pulse to the respective resonant circuit 6a-c.

[0112] In some examples, the command includes an instruction for the local controller 12a- c to provide feedback about the resonant circuit 6a-c to the central controller 4.

[0113] For example, the local controllers 6a-c are each configured to apply a pulse to the resonant circuit 6a-c (e.g. in response to a command from the central controller 4).

[0114] In some examples, an edge of the applied pulse induces a pulse response between the capacitive element 10a-c and the inductive element 8a-c of the resonant circuit 6a-c, wherein the pulse response has a resonant frequency.

[0115] Each of the local controllers 12a-c is further configured to receive feedback from the resonant circuit 6a-c. The feedback may be any desired information about the resonant circuit 6a-c. For example, the feedback may include a measurement and / or estimation of one or more of: a current, a voltage, a power, a resistance, a (resonant) frequency, a temperature and / or timing information relating to any of the elements of the resonant circuit 6a-c. In some examples, the feedback may be indicative of the response of the resonant circuit 6a-c to an applied pulse (e.g. a pulse that has been applied to the resonant circuit 6a-c by the local controller 12a-c in response to a command from the central controller 4). For example, the feedback indicative of the response of the resonant circuit 6a-c to an applied pulse may be the amplitude of the current and / or the estimated resonant frequency of the resonant circuit 6a-c.

[0116] Each of the local controllers 12a-c is further configured to send said feedback to the central controller 4. In some examples, this feedback may help to determine a variable relating to a subsequent pulse to be applied to the resonant circuit 6a-c. For example, the feedback may help to determine one or more of: the current, the voltage, the frequency, the duration, and / or the timing of any subsequent pulses that are to be applied to the resonant circuit 6a-c.

[0117] In some examples, the local controllers 12a-c and / or the central controller 4 may be configured to process the feedback that is received from the resonant circuit 6a-c. For example, the local controllers 12a-c and / or the central controller 4 may be configured to process the measurements of one or more variables related to the resonant circuit 6a-c in order to determine one or more variables related to any subsequent pulses that are to be applied to the resonant circuit 6a-c.

[0118] In this example, each of the induction units 7a-7c further includes a frequency estimation circuit 20 (only one is shown for clarity) and a current feedback circuit 22 (only one is shown for clarity). The frequency estimation circuit 20 and the current feedback circuit 22 of each induction units 7a-7c are each directly connected to the respective local controller 12a-c and to the inductive element 8a-c and / or the capacitive element 10a-c. The frequency estimation circuit 20 and the current feedback circuit 22 may be any known in the art.

[0119] Each of the frequency estimation circuits 20 may be configured to estimate the resonant frequency of the respective resonant circuit 6a-c. In particular, each of the frequency estimation circuits 20 may be configured to estimate the resonant frequency of the inductive element 8a-c and the capacitive element 10a-c. Therefore, the feedback received by the local controller 12a-c may be an estimation of the resonant frequency of the resonant circuit 6a-c.

[0120] Each of the current feedback circuits 22 may be configured to measure the current flowing through the respective resonant circuit 6a-c. In particular, each of the current feedback circuits 22 may be configured to measure the current flowing through the inductive element 8a-c and / or the capacitive element 10a-c. Therefore, the feedback received by the local controller 12a-c may be one or more measurements of the current flowing through the resonant circuit 6a-c.

[0121] It will be understood that the central controller 4 may interact with each local controller 12a-c independently, for example in a specific sequence. The central controller 4 may interact with two or more local controllers simultaneously. The central controller may interact with all local controllers simultaneously.

[0122] This arrangement provides a networked controller for the plurality of induction units.

[0123] With such an arrangement, each the local controller controls a respective induction unit and the main controller acts as a coordinating controller independent of the induction units. Therefore, a smaller, less powerful main controller can be used since it is only handling data transfer, i.e. sending commands and receiving feedback.

[0124] Furthermore, power is supplied directly to each induction unit which means that the high frequency signal path is minimised and losses are reduced. Additionally, the signal feedback is expected to be cleaner, since there is less noise due to the shorter path. This means that signal processing will be less complex.

[0125] Figure 2 shows a method for controlling a system 2 comprising a plurality of induction units 7a-c. Step 101 includes sending commands from a central controller 4 to at least one of the plurality of local controllers 12a-c, wherein each of the plurality of induction units 7a-c comprises a local controller 12a-c and a resonant circuit 6a-c. Step 102 includes applying, by at least one of the plurality of local controllers 12a-c, a pulse to the resonant circuit 6a-c of the induction unit 7a-c. Step 103 includes receiving, by at least one of the plurality of local controllers 12a-c, feedback from the resonant circuit 6a-c. Step 104 includes sending said feedback from at least one of the plurality of local controllers 12a-c to the central controller 4.

[0126] Figure 3a is a flow chart showing an algorithm, indicated generally by the reference numeral 26. The algorithm 26 may be implemented using the apparatus 2 described above.

[0127] The algorithm 26 starts in operation 27, where a resonant circuit (e.g. the resonant circuit 6a-c) is driven at a resonant frequency of the resonant circuit in a heating mode of operation. For example, the switching arrangement may be switched at a determined resonant frequency of the resonant circuit 6a-c (under the control of the control circuit). In this embodiment, the resonant circuit is driven at a predetermined starting resonant frequency.

[0128] In an alternative embodiment, the algorithm may start at operation 28, where the sampling mode is triggered prior to heating for the first time, in other words the sampling mode pings the susceptor prior to heating. The sampling mode determines frequency to start heating at. At operation 28, a sampling mode of operation is entered. The sampling mode may seek to determine the resonant frequency for use in the heating mode (e.g. during the next iteration of the algorithm 26). The sampling mode may include applying a pulse to the resonant circuit at a specified time interval and processing the resonant response to determine / estimate the resonant frequency.

[0129] In the apparatus of Figure 1 , the frequency can be determined by the frequency estimation circuit 20.

[0130] At operation 29, the driving frequency for the resonant circuit is set based on the determined resonant frequency.

[0131] Thus, the parameters of the heating mode (including the driving frequency and the sampling interval) are set in the operation 29. The heating of the susceptor occurs in the next iteration of the heating mode 27 until the time interval dictated by the sampling mode occurs. The algorithm 26 then re-enters the sampling mode 28 where the resonant frequency of the resonant circuit is again determined and the parameters of the heating and sampling modes are updated (in the operation 29).

[0132] In the apparatus of Figure 1 , the central controller may be used to determine how often to initiate the sampling mode 28. The central controller may seek to strike a balance between sampling sufficiently often to ensure that the resonant circuit is being driven at (or close to) its resonant frequency in the heating mode 27 (thereby tending to increase heating efficiency) and having a low sampling rate (i.e. a high sampling period) so that the susceptor spends a large proportion of its time being heated (again, tending to increase heating efficiency).

[0133] The sampling period (i.e. how often the sampling mode 28 is entered) may be a controllable variable.

[0134] Figure 3b is a flow chart showing an algorithm, indicated generally by the reference numeral 30, in accordance with an example embodiment. The algorithm 30 starts at operation 32, where the current flowing in the heater. In the apparatus of Figure 1, the frequency can be determined by the frequency estimation circuit 20. A high heater current indicates that the resonant circuit is being driven at, or close to, the resonant frequency. At operation 34, a sampling mode period is set based, at least in part, on the determined heater current. For example, the sampling mode period may be increased as the determined heater current increases and vice-versa (so that sampling is performed less often as the heater current increases).

[0135] The algorithm 140 may form part of the operation 29 of the algorithm 26.

[0136] Reducing the sampling period when the heater current is relatively low can increase heater efficiency by resetting the driving frequency (in an instance of the operation 29) more often. In other words, decreasing the sampling mode period if the measured current flowing in the inductive heater is reduced.

[0137] Conversely, if the heater current is high (e.g. at or close to the target current), then the sampling period can be increased so that the driving frequency is updated less often.

[0138] Figure 4a is a plot showing a pulse 140 in accordance with an example embodiment. The pulse 140 is includes a rising pulse edge 142 that is an example of a pulse edge that may be applied in the step 102. The pulse 140 may be generated in response to a command from a local controller 12a-c, via a respective bridge circuit 14, to a respective resonant circuit 6a-c in response to a command from the central controller 4. The pulse 140 may, for example, be applied to generate a pulse response for use in estimating temperature and / or resonant frequency.

[0139] In the apparatus of Figure 1, the central controller 4 sends a command to least one of the local controllers 12a-c, and the or each local controller 6a-c applies a pulse to its respective resonant circuit 6a-c. The applied pulse induces a pulse response between the capacitive element 10a-c and the inductive element 8a-c of the resonant circuit 6a-c.

[0140] The application of the pulse edge 142 to the resonant circuit 6a-c generates a pulse response. Figure 4b is a plot, indicated generally by the reference numeral 150, showing an example pulse response that might be generated at a connection point between the capacitive element 10a-c and the inductive element 8a of the resonant circuit 6a-c described above in response to the pulse edge 92. This response may be received by the local controller 12a-c in the step 103.

[0141] As shown in Figure 4b, the pulse response 150 may take the form of a ringing resonance. The pulse response is a result of charge bouncing between the capacitive element 10a-c and the inductive element 8a of the resonant circuit. As shown in Figure 4b a period 102 between zero-crossings can be used to determine a resonant frequency of the pulse response. Note that in some example embodiments other measurements may be taken, such as the period between successive peaks of the ringing response.

[0142] Figures 5a to 8e show non-combustible aerosol provision devices and systems which may be controlled in accordance with the principles described herein.

[0143] Figure 5a is a perspective illustration of an aerosol provision system 200 comprising an aerosol provision device 210 with an outer housing 221 and a replaceable article 250 (also known as a consumable) that may be inserted in the aerosol provision device 210. The aerosol provision device 210 may further comprise an activation switch 212 that may be used for switching on or switching off the aerosol provision device 220. In other embodiments, the device does not include an activation switch 212 and a pressure trigger or some other activation-on-demand arrangement may be provided.

[0144] Figure 5b shows the aerosol provision system 200 with a front portion of the outer housing removed. The aerosol generating device 210 comprises a plurality of inductive elements 8a, 8b, 8c surrounding a heating chamber 240 into which a distal end of the article 250 is inserted.

[0145] The plurality of inductive elements 8a-c may each form part of a resonant circuit, such as the resonant circuit 14. The or each inductive element 8a-c may comprise a helical inductor coil. In one example, the helical inductor coil is made from Litz wire / cable which is wound in a helical fashion to provide the helical inductor coil. In other embodiments, other types are inductor elements are provided, as inductors formed within a printed circuit board. The inductive elements may be the same or similar. The use of three inductive elements is not essential to all example embodiments. Thus, the aerosol generating device 210 may comprise one or more inductive elements.

[0146] The aerosol provision system 200 includes a susceptor 245 provided within the heating chamber 240, such that when the article is inserted into the heating chamber 240 and at least partially surrounded by the susceptor.

[0147] In use, the article 250 is received in the article chamber 240. The inductive elements 8a-c surround the susceptor 245. The inductive elements 8a-c induce a varying magnetic field in the susceptor 245, which causes heating of the susceptor 245. The susceptor 245 in turn heats aerosol generating material in the article 250.

[0148] Figure 5c shows an embodiment of an article 250 for use in an aerosol provision device 210 as described above, having a susceptor provided in the device. The article 250 comprises a mouthpiece 251, and a cylindrical rod of aerosol generating material 254 connected to the mouthpiece 251. The aerosol generating material 254 is wrapped in a wrapper 252. The wrapper 252 can, for instance, be a paper or paper-backed foil wrapper. The wrapper 252 may be substantially impermeable to air. In one embodiment, the wrapper 252 comprises aluminium foil.

[0149] The mouthpiece 251 , in the present example, includes a body of material 256 upstream of a hollow tubular element 255, in this example adjacent to and in an abutting relationship with the hollow tubular element 255. The body of material 256 and hollow tubular element 255 each define a substantially cylindrical overall outer shape and share a common longitudinal axis. The body of material 256 is wrapped in a first plug wrap 257. The mouthpiece 251 also includes a second hollow tubular element 258, also referred to as a cooling element, upstream of the first hollow tubular element 254. The body of material 256 and second hollow tubular element 258 each define a substantially cylindrical overall outer shape and share a common longitudinal axis. The second hollow tubular element 258 is formed from a plurality of layers of paper which are parallel wound, with butted seams, to form the tubular element 258. A second plug wrap 259 is also provided around the mouthpiece 251. The aerosol generating material 254, also referred to herein as an aerosol generating substrate 254, comprises at least one aerosol forming material. In the present example, the aerosol forming material is glycerol. In alternative examples, the aerosol forming material can be another material as described herein or a combination thereof. The aerosol generating substrate may comprise botanical material, for example tobacco.

[0150] In alternative embodiment, the susceptor 245 may be provided in the article 250, for example embedded in the aerosol generating material 254.

[0151] Figure 6a is a cross-sectional view through a schematic representation of an aerosol provision system 200 in accordance with another embodiment. The aerosol generating system 200 comprises an aerosol provision device 210 and an aerosol generating article 250.

[0152] The aerosol provision device 210 comprises an outer housing 221, a power source 222, control circuitry 223, a plurality of inductive elements 8a-8c, a chamber 240, a mouthpiece end 226, an air inlet 227, an air outlet 228, a touch-sensitive panel 229, an inhalation sensor 230, and an end of use indicator 231.

[0153] The outer housing 221 may be formed from any suitable material, for example a plastics material. The outer housing 221 is arranged such that the power source 222, control circuitry 223, aerosol generating components 224, chamber 240 and inhalation sensor 230 are located within the outer housing 221. The outer housing 221 also defines the air inlet 227 and air outlet 228, described in more detail below. The touch sensitive panel 229 and end of use indicator are located on the exterior of the outer housing 221. The outer housing 221 and mouthpiece end 226 are formed as a single component (that is, the mouthpiece end 226 forms a part of the outer housing 221). In other embodiments, the mouthpiece end 226 may be a removable component that is separate from but able to be coupled to the outer housing 221 , and may be removed for cleaning and / or replacement with another mouthpiece end 226. The chamber 240 is suitable sized to removably receive the aerosol generating article 250 therein. Although not shown, the aerosol provision device 210 may comprise a hinged door or removable part of the outer housing 221 to permit access to the chamber 240 such that a user may insert and / or remove the aerosol generating article 250 from the chamber 240 The hinged door or removable part of the outer housing 210 may also act to retain the aerosol generating article 250 within the chamber 240 when closed. Alternatively, the aerosol provision device 210 may include a permanent opening that communicates with the chamber 240 and through which the aerosol generating article 250 can be inserted into the chamber 240. In such implementations, a retaining mechanism for retaining the aerosol generating article 250 within the chamber 240 of the aerosol provision device 210 may be provided.

[0154] The power source 222 is configured to provide operating power to the aerosol provision device 210. The power source 222 may be any suitable power source, such as a battery. For example, the power source 222 may comprise a rechargeable battery, such as a Lithium Ion battery. The power source 222 may be removable or form an integrated part of the aerosol provision device 210. In some implementations, the power source 222 may be recharged through connection of the aerosol provision device 210 to an external power supply (such as mains power) through an associated connection port, such as a USB port (not shown) or via a suitable wireless receiver (not shown).

[0155] The control circuitry 223 is suitably configured I programmed to control the operation of the aerosol provision device to provide certain operating functions of aerosol provision device 210. The control circuitry 223 is connected to the power supply and receives power from the power source 222 and may be configured to distribute or control the power supply to other components of the aerosol provision device 210.

[0156] The aerosol provision device 210 further comprises a chamber 240 which is arranged to receive an aerosol generating article 250. The aerosol generating article comprises a carrier component 262 and aerosol generating material 254 (for example an aerosol generating film) provided on or within a surface of the carrier 262. The article 250 further comprises a susceptor material (not shown in Figure 4a).

[0157] The inductive elements 8a-c may be referred to as heating elements. The inductive elements 8a-8c are aligned along an axis parallel to a longitudinal axis of the device 210. Each inductive element aligns with a corresponding discrete portion of aerosol generating material 254, defining a respective aerosol generating region.

[0158] In some implementations, to improve the heat-transfer efficiency, the chamber may comprise components which apply a force to the surface of the carrier component 262 so as to press the carrier component 262 onto the inductive elements 8a-c, thereby increasing the efficiency of heat transfer via conduction to the aerosol generating material 254.

[0159] In other embodiments four or more inductive elements may be provided aligned along an axis parallel to the longitudinal axis of the device 210.

[0160] Figure 6b shows a schematic view of the article 250 from Figure 6a. The carrier component 262 is broadly cuboidal in shape has a length I, a width w and a thickness tc.

[0161] The aerosol generating article 250 comprises a plurality of discrete portions of aerosol generating material 254 disposed on a surface of the carrier component 262. The discrete portions of aerosol generating material 254 are separate from one another such that each of the discrete portions may be energised (e.g. heated) individually or selectively to produce an aerosol. The aerosol generating article 250 may comprise a plurality of portions of aerosol generating material all formed form the same aerosol generating material. Alternatively, the aerosol generating article 250 may comprise a plurality of portions of aerosol generating material 254 where at least two portions are formed from different aerosol generating material.

[0162] In this embodiment, the aerosol generating article 250 comprises three discrete portions of aerosol generating material 254, aligned along a central axis of the article in order to align with the inductive elements in the device 210. In other embodiments, a greater or lesser number of discrete portions may be provided, and / or the portions may be disposed in a different pattern so as to align with any arrangement of inductive elements in the aerosol provision device.

[0163] The carrier layer 262 comprises a heating layer 264 which acts as the susceptor 245 and a support layer 266. The aerosol generating material 254 is provided on a first side 264a of the heating layer 264. The aerosol generating material 254 is divided into the discrete portions which may be easily sequentially heated (e.g. one by one) during an aerosol generation session.

[0164] In the present example, the heating layer 264 is formed of an aluminium foil material. In other examples, the heating layer 264 may be formed of a different material, for example another metal or a metal alloy.

[0165] The support layer 266 is provided on a second side 264b of the heating layer 264. The support layer 266 comprises a single layer of material. The support layer 266 is formed entirely of the same material. In the present example, the support layer 266 is formed of paper or cardboard. The support layer 266 provides structural support to the heating layer 264. The support layer 266 provides structural support to the article 250.

[0166] In other embodiments, the article comprises a continuous layer of aerosol generating material provided on the carrier component 262.

[0167] In other embodiments, the carrier component 262 may comprise a single layer which is a heating layer 264 which acts as the susceptor 245.

[0168] In use, the article 250 is received in the article chamber 240. The inductive elements 8a-c surround the susceptor 245. The inductive elements 8a-c induce a varying magnetic field in the susceptor 245, which causes heating of the susceptor 245. The susceptor 245 in turn heats aerosol generating material in the article 250.

[0169] Figure 7a shows an isometric exploded view of an aerosol provision device 210 in accordance with another embodiment. The aerosol provision device 210 includes components that are broadly similar to those described in relation to Figure 5a, the same reference numbers are used and they should be understood to be broadly the same as their counterparts unless otherwise stated.

[0170] The device 210 comprises a plurality of inductive elements 8, which in this example are in a 2x5 configuration. In this embodiment, the device 210 includes a plurality of air inlet holes 227 and air transmission channels 237 to direct air to the inductive elements 8.

[0171] In another embodiment (not shown), each of the plurality of inductive elements 8 enclosed by the respective aerosol transmission channels have an individual air supply hole. It will be appreciated that in other embodiments, the device can have a single air inlet (as described previously).

[0172] Figure 7b shows an article 250 in accordance with another embodiment for use with the device of Figure 7a. The article 250 includes components that are broadly similar to those described in relation to Figure 6b, the same reference numbers are used and they should be understood to be broadly the same as their counterparts unless otherwise stated. In Figure 7b, the article 250 includes ten discrete portions of aerosol generating material 254 provided on a first side of a carrier component 262. The discrete portions are provided in a 2x5 grid. In this embodiment, the carrier component 262 comprises a heating layer 264.

[0173] It will be appreciated that in other embodiments, the carrier component 262 also includes a support layer.

[0174] In other embodiments, aerosol provision devices may be provided with any number of inductive elements may be provided in alternative grid configuration, for example a 2x3 grid, a 2x4 grid or a 3x3 grid.

[0175] In alternative embodiments, aerosol generating articles may be provided with the aerosol generating material 254 may be distributed in a different number of discrete portions and in different locations on the first side of the heating layer 264 as required. Figure 8a shows an aerosol provision system 200 in accordance with another embodiment. The aerosol provision device 210 includes components that are broadly similar to those described in relation to Figure 5a, the same reference numbers are used and they should be understood to be broadly the same as their counterparts unless otherwise stated.

[0176] The device 210 comprises a plurality of inductive elements 8a-j, which in this embodiment are provided in a first array 8a to e and a second array 8f to 8j. The first array of inductive elements 8a to 8e is provided on a first side of the chamber 240 and the second array 8f to 8j is provided on a second, opposite side of the chamber 240.

[0177] In other embodiments, the aerosol provision device 210 may comprise a hinged door or removable part of the outer housing 221 to permit access to the chamber 240 such that a user may insert and / or remove the aerosol generating article 250 from the chamber 240.

[0178] Figures 8b to 8e show various articles which can be used with the device of Figure 8a. The articles are broadly cuboidal in shape so as to be received in the chamber 240 of the device 210.

[0179] Figure 8b shows a cross-sectional view through an article 250 comprising a carrier component 262 comprising a heating layer 264. Discrete portions of aerosol generating material 254 are provided on a first side 264a and a second side 264b of the heating layer 264.

[0180] Figure 8c shows a cross-sectional view through an article 250 comprising a carrier component 262 comprising a support layer 266 and two heating layers 264, wherein the support layer is provided between the heating layers 264. Discrete portions of aerosol generating material 254 are provided on outer surfaces of the heating layers 264.

[0181] Figure 8d shows a cross-sectional view through an article 250 comprising a substantially cuboidal carrier component 262. The article defines an inner void 263 having with open first and second ends 262a, 262b. The carrier component 262 comprises a heating layer 264 provided on opposition sides of the inner void.

[0182] Discrete portions of aerosol generating material 254 are provided inner surfaces of the heating layers 264.

[0183] Figure 8e shows a cross-sectional view through an article 250 comprising a substantially cuboidal carrier component 262. The article defines an inner void 263 having with open first and second ends 262a, 262b. The carrier component 262 comprises a heating layer 264 and a support layer 266. Discrete portions of aerosol generating material 254 are provided on inner surfaces of the heating layer 264.

[0184] The various embodiments described herein are presented only to assist in understanding and teaching the claimed features. These embodiments are provided as a representative sample of embodiments only, and are not exhaustive and / or exclusive. It is to be understood that advantages, embodiments, examples, functions, features, structures, and / or other aspects described herein are not to be considered limitations on the scope of the invention as defined by the claims or limitations on equivalents to the claims, and that other embodiments may be utilised and modifications may be made without departing from the scope of the claimed invention. Various embodiments of the invention may suitably comprise, consist of, or consist essentially of, appropriate combinations of the disclosed elements, components, features, parts, steps, means, etc., other than those specifically described herein. In addition, this disclosure may include other inventions not presently claimed, but which may be claimed in future.

Claims

Claims1. An apparatus for an aerosol provision device comprising: a central controller; and a plurality of induction units; wherein each of the plurality of induction units comprises:- a resonant circuit comprising an inductive element, which is configured to inductively heat a susceptor; and a capacitive element; and- a local controller; wherein the local controller is configured to: receive one or more commands from the central controller; perform at least one action based on the one or more commands received from the central controller; and send feedback to the central controller.

2. The apparatus of claim 1, wherein the central controller is configured to send one or more commands to the local controllers relating to operation of the apparatus.

3. The apparatus of claim 1, wherein the central controller is configured to send one or more commands to the local controllers relating to one or more of the following: turning power on; turning power off; set power level to be applied through the resonant circuit; set a duration of on time.

4. The apparatus of any of claims 1 to 3, wherein the central controller is configured to send a command including an instruction to apply a pulse to a respective resonant circuit; and wherein the local controller is configured to: receive the command from the central controller; apply a pulse to the resonant circuit; receive feedback from the resonant circuit; and send said feedback to the central controller based on the feedback from the resonant circuit.

5. The apparatus of claim 4, wherein an edge of applied pulse induces a pulse response between the capacitive element and the inductive element of the resonant circuit, wherein the pulse response has a resonant frequency.

6. The apparatus of any of claims 4 or 5, wherein the feedback received by the local controller is an estimation of the resonant frequency of the resonant circuit.

7. The apparatus of any of claims 4 to 6, wherein the feedback received by the local controller is a measurement of the current flowing in the resonant circuit.

8. The apparatus of any preceding claim, wherein each of the plurality of induction units further comprises a bridge circuit configured to connect the inductive element and the capacitive element to the local controller.

9. The apparatus of any preceding claim, wherein the apparatus further comprises a power source, wherein the power source is configured to provide power to the central controller and each of the plurality of local controllers.

10. The apparatus of any preceding claim, wherein each of the plurality of local controllers and / or the central controller is configured to process the feedback that is received from the resonant circuit.

11. The apparatus of any preceding claim, wherein each of the plurality of induction units further comprises a frequency estimation circuit; wherein the frequency estimation circuit is configured to: estimate the resonant frequency of the resonant circuit; and provide feedback to the local controller.

12. The apparatus of any preceding claim, wherein each of the plurality of induction units further comprises a current feedback circuit; wherein the frequency estimation circuit is configured to: measure the current flowing through the resonant circuit; and provide feedback to the local controller.

13. The apparatus of any preceding claim, comprising at least five induction units.

14. The apparatus of claim 13, comprising ten induction units.

15. An aerosol provision device comprising the apparatus according to any of claims 1 to 14.

16. The aerosol provision device of claim 15, comprising a chamber for removably receiving an article comprising an aerosol generating material, wherein the inductive elements of the plurality of resonant circuits are arranged along a side wall of the chamber.

17. The aerosol provision device of claim 15, comprising a chamber for removably receiving an article comprising an aerosol generating material, wherein the inductive elements of the plurality of resonant circuits are arranged along two side walls of the chamber.

18. An aerosol provision system comprising the aerosol provision device of any of claims 15-17, and an article comprising an aerosol generating material.

19. The aerosol provision system of claim 18, wherein the article comprises a susceptor.

20. A method of generating aerosol comprising: providing an aerosol provision system according to claim 18 or 19, and at least partially inserting the aerosol generating article into the chamber.

21. A method for controlling an apparatus for an aerosol provision device comprising a central controller and a plurality of induction units, each induction unit comprising a local controller and a resonant circuit, the method comprising: a) sending one or more commands from the central controller to at least one of the plurality of local controllers; b) performing, by at least one of the plurality of local controllers, at least oneaction based on the one or more commands received from the central controller; and c) sending feedback from at least one of the plurality of local controllers to the central controller.

22. The method of claim 21 , wherein step a) comprises sending one or more commands to the plurality of local controllers relating to operation of the apparatus.

23. The method of claim 21 or 22, wherein step a) comprises sending one or more commands to the plurality of local controllers relating to one or more of the following: turning power on; turning power off; set power level to be applied through the resonant circuit; set a duration of on time.

24. The method according to any of claims 21 to 23, wherein step b) comprises: applying a pulse to the resonant circuit; receiving feedback from the resonant circuit; and in step c) the feedback sent to the central controller is based on the feedback from the resonant circuit.

25. A computer program comprising instructions for causing an apparatus for an aerosol provision device comprising a central controller and a plurality of induction units, each induction unit comprising a resonant circuit and a local controller, to perform at least the following: sending one or more commands from the central controller to at least one of a plurality of local controllers, wherein each local controller is associated with a respective resonant circuit; performing, by at least one of the plurality of local controllers, at least one action based on the one or more commands received from the central controller; and sending feedback from at least one of the plurality of local controllers to the central controller.

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