A method for controlling the heating of a susceptor of an aerosol generating device using a boost converter

Abstract

A method for controlling the heating of a susceptor of an aerosol generating device is described, wherein the susceptor is inductively heated by a vibration circuit (6) driven by an inverter (5), and an optional boost converter (8) is connected between a power unit (4) and the inverter (5), and the boost converter (8) is configured to boost the input voltage supplied from the power unit to an output voltage delivered to the inverter (5). The method includes a power transfer mode of the aerosol generating device and a temperature identification mode of the aerosol generating device in which the amount of power supplied to the inverter is less than the amount of power supplied during the power transfer mode. The method includes a step of determining the temperature of the susceptor, for example, based on a determined resonant frequency or resonant capacitor voltage of the vibration circuit (6). The power transfer mode may include a step of setting the output voltage delivered from the boost converter (8) to the inverter (5) according to the determined temperature of the susceptor.

Description

Technology Field

[0001] The present disclosure generally relates to a method for controlling the heating of a susceptor of an aerosol generating device, and an aerosol generating device comprising a controller configured to implement said method. Background Technology

[0002] An aerosol generating device generally comprises at least one storage container arranged to store an aerosol generating product. The aerosol generating product is heated without combustion to generate an aerosol for inhalation.

[0003] Aerosol generating products can be heated using various methods. One method consists of using induction heating. Accordingly, such aerosol generating devices generally include an induction heating system comprising an induction coil, an induction heating susceptor, and a power unit.

[0004] Thanks to a power unit or battery, electrical energy is supplied to the induction coil by an inverter. Consequently, the induction coil generates an alternating electromagnetic field. The susceptor is coupled to the electromagnetic field to generate heat, which is then transferred to the aerosol-generating product, for example, by conduction. Finally, the heated aerosol-generating product produces an aerosol.

[0005] For the optimized operation of an aerosol generating device, it is necessary to seek the highest possible energy efficiency during induction heating.

[0006] In this context, for example, it is known to use a boost converter for an aerosol generating device. The boost converter is configured to step up the voltage supplied by a power unit, that is, to convert a DC voltage into a higher value DC voltage. Such an aerosol generating device is disclosed in CN209732613U.

[0007] The present disclosure aims to provide an improved method for controlling the induction heating of a susceptor of an aerosol generating device, and more specifically, to improve energy efficiency by using a boost converter. means of solving the problem

[0008] Accordingly, the present disclosure relates to a method for controlling the heating of a susceptor of an aerosol generating device, wherein the susceptor is inductively heated by a vibration circuit driven by an inverter.

[0009] According to a first aspect of the present disclosure, the method comprises a power transfer mode of an aerosol generating device and a temperature identification mode of an aerosol generating device in which the amount of power supplied to the inverter is less than the amount of power supplied during the power transfer mode, and the method further comprises the step of determining the temperature of a susceptor based on a measurement made during the temperature identification mode.

[0010] A boost converter may be connected between the power unit and the inverter, and the boost converter is configured to boost the input voltage supplied from the power unit to an output voltage delivered to the inverter. The power delivery mode may include a step of setting the output voltage delivered from the boost converter to the inverter according to a determined temperature of the susceptor.

[0011] Therefore, efficient power control is possible by adjusting the voltage delivered to the vibration circuit based on the temperature of the susceptor and the resulting temperature of the aerosol-generating product. By determining the temperature of the aerosol-generating product and controlling the delivery voltage accordingly, an appropriate amount of aerosol can be produced using a suitable material with high energy efficiency.

[0012] Therefore, the output voltage may vary depending on the desired heating profile, which depends on other parameters such as the characteristics or type of the aerosol-generated product.

[0013] In addition, the boost converter provides smooth power control in induction heating, which is difficult to control.

[0014] The method may include a comparison step performed before the setting step, which compares the determined temperature of the susceptor with the target temperature, and the output voltage is set to a value that varies depending on the determined temperature and the target temperature.

[0015] Therefore, the output voltage can vary depending on the target temperature. For example, the output voltage can be controlled to reach the target temperature without exceeding it. Conversely, the output voltage can be controlled to overshoot the target temperature.

[0016] The aerosol generating device may include a controller configured to control the output voltage of a boost converter to raise the temperature of the susceptor to a target temperature, said controller is tuned to be overdamped, and the output voltage is set to a predefined maximum voltage when the determined temperature of the susceptor is below a threshold value.

[0017] The threshold value may be in the range of 60% to 85% of the target temperature.

[0018] The aerosol generating device may include a controller configured to control the output voltage of a boost converter to make the temperature of the susceptor reach a target temperature, said controller is tuned to under-damped, and the output voltage is set so that the temperature of the susceptor overshoots the target temperature at the start of heating of the susceptor.

[0019] The controller can be a PID controller, a model-based controller, and / or a model-predictive controller.

[0020] The output voltage can be set to substantially equal to or less than a predetermined voltage, for example, about 8 V, when the determined temperature of the susceptor is equal to the target temperature.

[0021] The boost converter can be an asynchronous boost converter.

[0022] The boost converter can be a synchronous boost converter.

[0023] The boost converter may include an active switch, and the active switch is a MOSFET transistor.

[0024] The boost converter may include a passive switch, and the passive switch is a MOSFET transistor.

[0025] The boost converter may be configured to step up an input voltage in the range of 3 to 4.2 V to a desired output voltage. The desired output voltage will be sufficient to generate appropriate losses within the susceptor for the necessary heating, and in some embodiments, the desired output voltage may be equal to at least 8 V. The desired output voltage may vary depending on susceptor characteristics such as resistance, shape, and size.

[0026] If a boost converter is not required, the inverter can be controlled by a controller to regulate induction heating during power delivery mode. For example, the inverter can be periodically enabled and disabled (or periodically controlled to be on and off) with a duty cycle that can be changed to control the heating of the susceptor. This operation may be referred to as a "global" pulse width modulation (PWM) control scheme in which the time (or "pulse width") during which the inverter is enabled changes. The inverter may include two transistors. During the period when the inverter is enabled (or in the on-state), the transistors may operate with a predetermined duty cycle. During the period when the inverter is disabled (or in the off-state), both transistors are turned off.

[0027] The inverter may include two transistors. Both transistors are preferably operated during the power transfer mode.

[0028] The oscillating circuit may include a coil circuit and a susceptor circuit. The coil circuit may be, for example, an LLC circuit or an LC circuit, and will generally include at least one inductor or coil and at least one capacitor. In some aspects of the present disclosure, an LC circuit may be preferred because it includes fewer power dissipation components. In an LLC circuit, an additional filter inductor may increase resistive power loss and increase the required battery voltage. This may also lead to greater switching losses in the inverter.

[0029] The determination of the susceptor temperature can be based on the determined resonant frequency of the vibration circuit.

[0030] The above temperature determination step may include the following sub-steps:

[0031] - A step of operating only one of the two transistors of the inverter during temperature identification mode;

[0032] - A step of determining the resonance frequency of the vibration circuit during the temperature identification mode; and

[0033] - A step of determining the temperature of the susceptor based on the resonant frequency determined above.

[0034] The determination of the susceptor temperature can be based on the determined maximum value of the indicated electrical value within the vibration circuit, for example, based on the voltage across the capacitor of the coil circuit.

[0035] The above temperature determination step may include the following sub-steps:

[0036] - For example, minimum frequency (f min ) and maximum frequency (f maxA step of determining the maximum value of the display electrical value within the vibration circuit for the frequency range during the temperature identification mode while sweeping the frequency in the range between );

[0037] - A step of determining a global maximum value from a determined maximum value; and

[0038] - A step of determining the temperature of the susceptor based on the above global maximum value.

[0039] The temperature determination step may further include a substep of operating both transistors of the inverter during the temperature identification mode with a reduced duty cycle of, for example, about 10% to 15%. More specifically, the duty cycle of the inverter during the temperature identification mode is preferably smaller than the duty cycle of the inverter during the power transfer mode. In order to ensure that as little power as possible is delivered to the susceptor, the duty cycle during the temperature identification mode is preferably reduced to a minimum value. For example, susceptor heating during a single frequency sweep can be maintained at less than 1°C, which is sufficient to ensure high performance.

[0040] The above global maximum value and / or the substep of determining the susceptor temperature based on the above global maximum value does not need to be executed during the temperature identification mode. In other words, while the measurements required to determine the susceptor temperature may be performed during the temperature identification mode, the processing to actually determine the susceptor temperature may be performed after the temperature identification mode has ended.

[0041] During the operation of the aerosol generating device, the power transfer mode and the temperature identification mode can be performed alternately.

[0042] The temperature identification mode can be executed at regular time intervals.

[0043] According to a second aspect of the present disclosure, a method for controlling the heating of a susceptor of an aerosol generating device is provided, wherein the susceptor is inductively heated by a vibration circuit driven by an inverter, and a boost converter is connected between a power unit and the inverter, and the boost converter is configured to boost an input voltage supplied by the power unit to an output voltage delivered to the inverter, and the method comprises a power delivery mode of the aerosol generating device and a temperature identification mode of the aerosol generating device in which the amount of power supplied to the inverter is less than the amount of power supplied during the power delivery mode, and the method further comprises the step of determining the temperature of the susceptor and setting the output voltage delivered from the boost converter to the inverter during the power delivery mode according to the determined temperature of the susceptor.

[0044] Other features of the aerosol generating device and method are as described above.

[0045] According to a third aspect of the present disclosure, an aerosol generating device is provided, and such aerosol generating device,

[0046] Power unit;

[0047] Induction heating susceptor;

[0048] A vibration circuit arranged to generate a time-varying electromagnetic field for inductive heating of the susceptor;

[0049] An inverter configured to drive a vibration circuit;

[0050] An optional boost converter connected to a power unit on one side and an inverter on the other side; and

[0051] A controller configured to implement a method for controlling the heating of a susceptor as described above

[0052] Includes Brief explanation of the drawing

[0053] Other features and advantages of the present disclosure will also become apparent from the following description. The attached drawings are provided as a non-limiting example: FIGS. 1a and FIGS. 1b schematically show parts of an aerosol generating device (1) according to two embodiments of the present disclosure. Figure 2 schematically shows the electronic circuit elements of an aerosol generating device. FIG. 3 schematically illustrates a control loop system according to an embodiment of the present disclosure. Figure 4a shows the vibration circuit and inverter of Figure 2. FIG. 4b shows a vibration circuit and an inverter according to another embodiment of the present disclosure. Figure 5a separately shows the boost converter circuit of Figure 2. FIG. 5b shows a boost converter circuit according to another embodiment of the present disclosure. Figure 6 shows the linear dependence between the resonance frequency of the vibration circuit of the aerosol generating device and the temperature of the susceptor. Figure 7 schematically illustrates a method for controlling the induction heating of a susceptor of an aerosol generating device. Figure 8 shows an example of temperature control that can be implemented in an aerosol generating device. Figure 9 shows the dependence between the voltage of the vibration circuit of the aerosol generating device and the temperature of the susceptor. Specific details for implementing the invention

[0054] Now, embodiments of the present disclosure will be described merely as examples and with reference to the accompanying drawings.

[0055] FIGS. 1a and 1b schematically illustrate parts of an aerosol generating device (1) according to two different embodiments of the present disclosure. FIGS. 1a and 1b both schematically illustrate the mechanical configuration of the aerosol generating device (1), whereas FIG. 2 illustrates an example of an electronic circuit element of the aerosol generating device (1).

[0056] The aerosol generating device (1) includes a main body (2) and a cartridge (3).

[0057] The cartridge (3) includes a first end (30) configured to be coupled with the main body (2), and a second end (31) arranged as a mouthpiece portion (not shown) having a steam outlet.

[0058] The cartridge (3) further includes at least one storage container (32) arranged to store an aerosol generating product (33). The cartridge (3) may be disposable.

[0059] A storage container (32) is positioned to receive a correspondingly molded aerosol generating product (33). The aerosol generating product (33) and / or the storage container may be a disposable item or a stick.

[0060] The term aerosol-generating product is used to denote any material that can be evaporated into the air to form an aerosol. Evaporation is generally achieved by increasing the temperature to the boiling point of the evaporable material, such as up to 400°C, preferably up to 350°C. The evaporable material may be, for example, in liquid, solid, or semi-liquid form, and accordingly may include or consist of liquids, tobacco, gels, waxes, or other substances, or any combination thereof.

[0061] The mouthpiece is removable so as to allow access to the storage container to insert or remove the aerosol generating product (33).

[0062] The aerosol generating device (1) includes an induction heating system configured to heat an aerosol generating product (33).

[0063] The induction heating system generally includes a power unit or battery (4) placed within the main body (2), as well as an inverter (5) and a controller (9) (identifiable in FIG. 3).

[0064] The controller (9) is configured to operate other electronic components, including the inverter (5).

[0065] An inverter (5) is configured to convert direct current from a battery (4) into high-frequency alternating current. The inverter (5) includes two switches or transistors (T0, T1). The transistors (T0, T1) operate at the same frequency and at a predetermined duty cycle. In particular, the duty cycle of the two transistors (T0, T1) of the inverter (5) is 50%. It will be understood that while a 50% duty cycle is generally preferred during power delivery mode so that the transistors (T0, T1) have symmetrical loads, other duty cycles are also possible. Additionally, the transistors (T0, T1) can be operated with a variable duty cycle, for example, a duty cycle of about 20% to 80%. This may be appropriate in cases where there is no boost converter to adjust the voltage supplied to the inverter and no other method to control power delivery.

[0066] The induction heating system further includes a vibration circuit (6). The vibration circuit includes an inductance provided by a coil (60).

[0067] The coil (60) is a helical induction coil extending around the storage container (32). The induction coil (60) is powered by energy from the battery (4) and the controller (9). The controller (9) is at an operating frequency (f) at which the vibration circuit (6) is driven. op It is configured to control ).

[0068] The induction heating system also includes one or more induction heating susceptors (7). A susceptor is an element made of an electrically conductive material and used to heat a non-electrically conductive material or product.

[0069] The induction heating type susceptor (7) can come into direct or indirect contact with the aerosol generating product (33), and accordingly, when the susceptor (7) is inductively heated by the induction coil (60), heat is transferred from the susceptor (7) to the aerosol generating product to heat the aerosol generating product and thereby generate an aerosol.

[0070] In the example illustrated in FIG. 1a, the susceptor (7) extends within a storage container (32) having an aerosol generating product (33). The susceptor (7) is preferably placed within the aerosol generating product (33).

[0071] In another embodiment illustrated in FIG. 1b, the susceptor (7) extends from the outside of the aerosol generating product (33). The susceptor (7) preferably extends along the lateral wall (320) of the storage container (32).

[0072] FIG. 2 shows a vibration circuit (6) comprising a battery circuit (40); an inverter circuit (50); a coil circuit (61) and a susceptor circuit (62). The vibration circuit (6) is shown separately in FIG. 4a. FIG. 4b also shows another example of a suitable vibration circuit.

[0073] In the embodiment of FIG. 4a, the coil circuit (61) is an LCC circuit having an additional inductor. A voltage sensor (63) is configured to measure the voltage across the capacitor (C) of the coil circuit (61).

[0074] In the embodiment of FIG. 4b, the coil circuit (61) is an LC circuit. A voltage sensor (64) is configured to measure the voltage across one of the capacitors (C2) of the coil circuit (61).

[0075] The aerosol generating device (1) also includes a boost converter (8), and an example of the circuit (80) of the boost converter is shown in FIG. 2. In particular, FIG. 2 includes an example of a boost converter (8) that can be used in an aerosol generating device and is separately shown in FIG. 5a. FIG. 5b also shows another example of a suitable boost converter (8).

[0076] The boost converter (8) is connected to the battery (4) in one part and to the inverter (5) in the other part. In some embodiments of the present disclosure, the boost converter (8) may be omitted, and the inverter (5) may be directly connected to the battery (4) or another power source. In the absence of the boost converter, the induction heating of the susceptor (7) during the power transfer mode described below may be controlled by a controller using a "global" PWM control scheme. The inverter (5) may be operated in the ON state, where transistors (T0, T1) are switched ON and OFF with a predetermined duty cycle. In particular, the duty cycle of the two transistors (T0, T1) of the inverter (5) is 50%. When the inverter (5) is operated in the OFF state, the two transistors (T0, T1) are switched OFF. The heating of the susceptor (7) during the power transfer mode may be changed by controlling the entire duty cycle of the "global" PWM control scheme.

[0077] The boost converter (8) is configured to boost the voltage, that is, to convert the DC voltage into a higher value DC voltage. More precisely, the boost converter (8) is configured to use the input voltage (V) supplied from the power unit (4). in A higher output voltage (V) delivered to the inverter (5) from ) out It is configured to boost to ).

[0078] The boost converter (8) is an advantageous solution for increasing voltage in minimal space.

[0079] A boost converter is a type of switch-mode power supply. Specifically, it uses a main switch, such as a transistor, to turn on and off parts of the circuit at a specific speed.

[0080] The boost converter (8) includes an active switch (T2) and a passive switch (T3).

[0081] The active switch (T2) or main switch is a MOSFET (Metal-oxide Semiconductor Field Effect Transistor) in both of the shown examples.

[0082] In the embodiment of FIG. 5a, the passive switch (T3) or auxiliary switch is a diode. Thus, the boost converter is an asynchronous boost converter.

[0083] In the embodiment of FIG. 5b, the passive switch (T3) is a MOSFET transistor. Thus, the boost converter (8) is a synchronous boost converter.

[0084] The boost converter (8) additionally includes an inductor (81) and a capacitor (82).

[0085] The boost converter circuit (80) further includes two sensors, which are a current sensor (83) and a voltage sensor (84). The current sensor (83) is configured to measure the output current delivered by the boost converter (8). The voltage sensor (84) measures the output voltage (V) delivered by the boost converter (8). out It is configured to measure ).

[0086] The principle of the boost converter consists of two distinct states, namely an on state and an off state. In the on state, the main switch (T2) is on, and the inductor (81) is charged. In the off state, the main switch (T2) is off, and the energy of the inductor (81) begins to dissipate.

[0087] The boost converter (8) is also characterized by a duty cycle (D). The duty cycle (D) represents a fraction of the rectification period (T) during which the main switch (T2) is on. Thus, D has a range of 0 to 1.

[0088] Average output voltage (V out ) is the input voltage (V) as shown in the following relationship. in It is directly related to ) and the duty cycle (D): .

[0089] The boost converter here uses an input voltage (V) in the range of 3 to 4.2 V. in A higher output voltage (V) from ) out It is configured to step up to ). Output voltage (V out ) is preferably at least 8 V.

[0090] The controller (9) is configured here to control the boost converter (8), specifically to control the output voltage delivered to the inverter (5).

[0091] FIG. 3 illustrates an example of a control loop system that can be used in the present disclosure. The controller (9) is connected to an inverter (5) on one side and to a boost converter (8) on the other side.

[0092] The controller (9) is, for example, a proportional-integral-derivative controller (PID controller).

[0093] For more advanced control and better performance, other topologies or controller types may be used. The controller (9) may be, for example, a model-based controller. Such a controller has the advantage of being able to account for the dynamic response of the system that changes according to operating conditions. Compared to a general PID controller, a model-based controller provides significantly better performance and is much less sensitive to changes in system characteristics. This enables, for example, a rapid rise or fall in temperature when necessary.

[0094] In another specific embodiment, the controller (9) may be a model-predictive controller or a model-based predictive controller. Such a controller may also represent the behavior of a dynamic system and additionally use a model of the system to predict the future behavior of the system.

[0095] Hybrid or mixed control may also be used. For example, if the aerosol generating device includes a boost converter (8), the boost converter may be controlled by the controller (9) for some operation of the aerosol generating device (e.g., during preheating), while for other operation (e.g., during the vaping phase), the boost converter may be bypassed or disabled, and the induction heating of the susceptor (7) may be controlled by an inductor, for example, using the aforementioned "global" PWM control scheme. During preheating, more power is required, and the boost converter (8) may be advantageous in providing a higher output voltage for the inverter (5). A higher voltage means that a lower current is required to achieve the same power, which can reduce losses. Subsequently, during the vaping phase, less power is required, and the boost converter (8) is not needed. By bypassing the boost converter (8), conduction losses can be reduced accordingly.

[0096] A method for controlling the heating of the susceptor (7) of an aerosol generating device (1) first includes the step of determining the temperature of the susceptor (7).

[0097] The temperature of the susceptor (7) can be determined using any suitable method. For example, the temperature of the susceptor (7) can be determined by first determining the resonant frequency of the vibration circuit (6).

[0098] In fact, the resonance frequency (f) of the vibration circuit r) is affected by the values ​​of inductance (L), resistance (R), and capacitance (82), and in the LLC circuit shown in FIG. 4a, the following is given:

[0099]

[0100] In addition, the resonance frequency (f) of the vibration circuit (6) r )Is:

[0101] - The precise position of the susceptor (7) relative to the inductance coil (60) of the vibration circuit (6); and

[0102] - Resistance of the susceptor (7) that changes according to the temperature of the susceptor

[0103] It depends on.

[0104] Changes in resistance can also be affected by manufacturing tolerances.

[0105] Therefore, the resonance frequency (f r By using ), the change in total resistance and the temperature of the susceptor (7) can be tracked.

[0106] More specifically, the resonant frequency (f r As shown in FIG. 6, it changes linearly with temperature. A function equation describing the temperature (T) of the susceptor (7) as a function of the frequency characteristic (F) can be written as F(T) = aT + b, where 'a' and 'b' are constant parameters of the function equation. The parameter 'a' corresponds to the slope value of the frequency curve. The parameter 'b' corresponds to the y-intercept.

[0107] The different curves in FIG. 6 represent variations in the frequency of the vibration circuit according to the temperature and position of the susceptor (7). In fact, as previously mentioned, the resonant frequency depends on the position of the susceptor (7) relative to the vibration circuit. Accordingly, this changes the y-intercept of the frequency curve. This is clearly shown in FIG. 6, where the slope 'a' is the same for all curves and the y-intercept differs for each curve.

[0108] In the illustrated embodiment, the y-intercept or b parameter is the initial resonant frequency (f) of the resonant circuit. i Corresponds to ). Initial resonance frequency (f i ) will refer to the resonant frequency of the vibration circuit before heating of the susceptor (7). In other words, the resonant frequency corresponds to the resonant frequency when the susceptor (7) is at ambient temperature, i.e., about 20°C.

[0109] Therefore, the illustrated curve shows that improper insertion of the susceptor (7) within the aerosol generating device can be taken into account.

[0110] The temperature of the susceptor (7) can be determined by first determining the resonant capacitor voltage of the vibration circuit (6). In fact, the resonant capacitor voltage (V) of the vibration circuit at the resonant frequency c ) is inductance (L), resistance (R), and supply voltage (V s Influenced by ), the following is given in the LC circuit shown in Fig. 4b:

[0111]

[0112] Accordingly, the resonant capacitor voltage varies according to the resistance of the susceptor (7), which changes according to the temperature of the susceptor.

[0113] Preferably, with a boost converter (8), the determining step is at a low power supply, i.e., a low output voltage (V out It is performed with a low output voltage (V). out ) will mean 8 V or less. Preferably, the output voltage at a low power supply is substantially equal to 8 V. Performing the determination step at a low power supply allows the temperature of the susceptor to be determined more accurately. In addition, this enables minimum energy consumption, which is advantageous because energy conversion for heating is not the purpose of this step.

[0114] A method for controlling the heating of the susceptor (7) is to control the determined temperature (T) of the susceptor (7).d ) a predefined temperature or target temperature (T t It additionally includes a comparison step that performs a comparison with ). The target temperature will mean a predefined and preset temperature that is intended for accurate aerosolization of the aerosol-generating product and must be maintained for accurate aerosolization.

[0115] A controller or aerosol generating device (1) controls the preset temperature or target temperature (T) of the susceptor (7). t You will understand that it can be configured to store ). The controller or aerosol generating device can also store the determined temperature (T d ) stored target temperature (T t It may include a comparator that compares with ).

[0116] Next, the method is the determined temperature (T) of the susceptor (7). d The output voltage (V) transferred from the boost converter (8) to the inverter (5) according to ) out Includes the step of setting ).

[0117] Output voltage (V) of the boost converter (8) out ) is the temperature of the susceptor (7) at the target temperature (T t It can be adjusted to be maintained after reaching ).

[0118] The controller determines the temperature (T) of the susceptor (7). d Output voltage (V) depending on ) out It operates as a closed loop that adjusts ).

[0119] For example, the determined temperature (T d ) is the target temperature (T t If it is less than ), a high power supply to the inverter (5) is maintained. The high power supply is a high output voltage (V out It will mean ). High output voltage (V out ) is higher than 8 V. Target temperature (T t When ) is reached, the power supply can be reduced. Target temperature (Tt When it reaches ), the power supply is set very low. In other words, the output voltage (V out ) is set to a low value, preferably 8 V or less.

[0120] The heating process and the consequent control of the output voltage depend on design-related selections and changes that vary according to parameters such as the properties or type of the aerosol product, the desired heating profile, etc.

[0121] Accordingly, by repeating the determination step and the setting step during the operation of the aerosol generating device, the voltage delivered to the vibration circuit (6) can be frequently adjusted. This enables good power control and energy efficiency.

[0122] For example, the determination step and the setting step are repeated at specific intervals during the operation of the aerosol generating device. The determination step and the setting step are repeated at regular intervals.

[0123] In another embodiment, the determination step and the setting step may be repeated continuously during the operation of the aerosol generating device.

[0124] An example of such a method for controlling the heating of the susceptor (7) is shown in FIG. 7.

[0125] In FIG. 7, T refers to the temperature of the susceptor (7), and V c represents the voltage across the capacitor of the vibration circuit, T0 and T1 are two transistors of the inverter (5), F is the frequency of the vibration circuit (6), and V out is the output voltage delivered by the boost converter (8). All these parameters are expressed as a function of time.

[0126] First, the initial resonance frequency (f) of the vibration circuit i ) is determined. This first step is S in Fig. 7. in It is indicated by and is also referred to as the initialization phase. Initialization phase (Sin ) is performed when the susceptor (7) is at room temperature, that is, before heating.

[0127] Initial resonance frequency (f i To determine ), low power energy is supplied to the vibration circuit (6). In particular, only the transistor (T0) of the inverter (5) is operated, and the transistor (T1) is off. The output voltage (V) of the boost converter out ) is set to a low value, preferably 8 V or less. More preferably, the output voltage (V out ) is 8 V.

[0128] Next, the operating frequency (f) of the inverter (5) op The initial resonant frequency (f) for which ) is determined i It is set in ). A method for controlling the heating of the susceptor (7) is set in a power transfer mode (S p ) and temperature identification mode(S Ti Includes ) additionally.

[0129] Power transfer mode (S p ) is performed during the heating of the susceptor (7). During this mode, both transistors (T0, T1) of the inverter (5) are operated. Output voltage (V out ) is generally set to a high value. That is, the output voltage (V out ) is set to a value greater than 8 V.

[0130] While heating the susceptor (7), the resonant frequency (f r ) is continuously tracked. In effect, the resonant frequency changes while the aerosol generator is functioning. Also, the resonant frequency (f r Operation in ) ensures the highest possible energy efficiency.

[0131] Therefore, the controller is in power transfer mode (S p At the resonant frequency (f) r ) tracks the actual operating frequency (f) during heating accordingly. op Adjusts the ). In other words, the operating frequency (fop ) is continuously updated accordingly to correspond to the resonant frequency of the vibration circuit.

[0132] Since the resonance frequency is tracked continuously, the temperature can be continuously determined using the curve of Fig. 6.

[0133] When using this method to control heating, the temperature of the susceptor (7) is in the power transfer mode (S p It can be continuously monitored during.

[0134] However, a better and more accurate temperature determination of the susceptor (7) is required. This is achieved using a temperature identification mode (S) performed at specific time intervals. Ti It can be accomplished by ).

[0135] To this end, after the power supply is cut off, low power energy is supplied to the oscillating circuit. Specifically, only transistor (T0) is operated, and transistor (T1) is turned off. Also, the output voltage (V out ) decreases. Output voltage (V out ) is lowered to a value of 8 V or less.

[0136] Next, the resonant frequency is determined. Subsequently, the temperature of the susceptor (7) can be determined using the curve shown in FIG. 6. In practice, the same curve corresponding to the initial resonant frequency is used to determine the temperature of the susceptor. In this disclosure, as previously stated, the resonant frequency (f r As shown in FIG. 6, the frequency characteristic (F) changes linearly with temperature. A function equation describing the temperature (T) of the susceptor (7) as a function of the frequency characteristic (F) can be written as F(T) = aT + b, where 'a' and 'b' are constant parameters of the function equation. The parameter 'a' corresponds to the slope value of the frequency curve. The parameter 'b' corresponds to the y-intercept. The frequency range is approximately 300 kHz to approximately 700 kHz, but can also be approximately 100 kHz to approximately 700 kHz.

[0137] The curve as shown in Fig. 6 is adjusted after the initial resonant frequency is determined. Subsequently, the curve may or may not be shifted according to the mathematical formula implemented in the controller.

[0138] In another embodiment, the curve may be implemented as a reference table. The reference table may be registered in the memory of the aerosol generating device.

[0139] Therefore, at specific intervals, temperature identification mode (S Ti Thanks to this, the temperature of the susceptor is accurately identified, and accordingly, this temperature is set to the target temperature (T t Maintains in ).

[0140] Temperature identification mode (S Ti Reducing the power delivered to the vibration circuit (6) during this process can prevent power delivery to the susceptor (7). In this way, the effect on the temperature of the susceptor (7) is reduced, which allows for a better estimation of the temperature of the aerosol-generating product (33).

[0141] Power transfer mode (S p ) and temperature identification mode(S Ti ) can be configured alternately.

[0142] Temperature identification mode (S Ti ) can be repeated at regular intervals to determine the accurate temperature.

[0143] In the example shown, the power transfer mode (S p ) and temperature identification mode(S Ti ) is regularly repeated and configured alternately. However, the power transfer mode (S p ) and temperature identification mode(S Ti The duration of ) may change during the function of the aerosol generating device. Depending on the operating factor, the temperature identification mode (S Ti It may be advantageous to reduce the frequency with which ) is executed. For example, during the initial heating phase, the power transfer mode (Sp It may be advantageous to extend the length of ), and this is the temperature identification mode (S Ti It will reduce the frequency with which ) is executed.

[0144] Each power transfer mode (S p The duration of ) can be, for example, in the range of about 30 to 200 ms.

[0145] For stable temperature determination of the susceptor, each temperature identification mode (S Ti The duration of ) may be very short, for example, in the range of about 2 to 20 ms. Each temperature identification mode (S Ti The duration of the ) may vary depending on other operating factors, such as the frequency range to be swept and the required resolution. In some cases, for a frequency sweep over a wider frequency range described below at high resolution, the duration of a specific temperature identification mode may be longer than about 20 ms, for example, about 120 ms. The first temperature identification mode may be longer than the subsequent temperature identification mode and accordingly enable a wider frequency range (e.g., 100 kHz to 700 kHz), and the subsequent temperature identification mode may utilize a narrower frequency range (e.g., 350 kHz to 450 kHz). The initial frequency sweep is executed over a wide frequency range at low resolution to identify an appropriate resonant frequency, and the subsequent frequency sweep is executed over a narrower frequency range at high resolution for more accurate temperature estimation. The narrower frequency range may target the approximate resonant frequency identified in the initial frequency sweep.

[0146] The temperature fluctuation of the susceptor during each temperature identification mode may be less than about 1°C.

[0147] FIG. 7 illustrates the temperature of the susceptor (7) increasing over time due to induction heating. The temperature of the susceptor (7) is a predefined temperature or a target temperature (T t It increases until it reaches ).

[0148] The temperature of the susceptor (7) is controlled here using smooth (slow or over-damped) control. In other words, the controller (9) is tuned to be over-damped. Over-damping would mean that the damping ratio is clearly greater than 1. Accordingly, the temperature of the susceptor (7) is the target temperature (T t It gradually increases up to ). Tuning the controller (9) to be over-damped prevents or at least reduces temperature overshoot.

[0149] Therefore, the controller sets an appropriate output voltage (V) so that the susceptor temperature becomes the desired temperature. out Apply ).

[0150] For example, if the determined temperature is below the target temperature, the power supply to the inverter (5) is a high output voltage (V out It is maintained at the target temperature (T t When it reaches ), the power supply can be reduced. For example, a threshold value is preset, and when this threshold value is exceeded, the temperature becomes the target temperature (T t It is considered to be approaching ). When the target temperature is reached, the power supply is set very low. That is, the output voltage (V out ) is set to a low value.

[0151] When using over-damped temperature control as in FIG. 7, if the determined temperature is less than a preset percentage of the target temperature, the output voltage supplied to the inverter (5) is a preset maximum voltage (V m The pressure can be increased up to ). Preferably, the threshold value or preset percentage is the target temperature (T tIt is 60% to 85% of ). The threshold value depends on other parameters, particularly the heating rate of the susceptor. For example, if the preheating or first-puff time is set to be very rapid, e.g., 2 seconds, a lower limit, namely about 60% of the target temperature, is desirable. In effect, this prevents overshooting caused by a thermal delay in temperature determination. Preheating or the first puff will refer to the first time cycle of each use of the aerosol generating device, i.e., when the user puffs for the first time.

[0152] The power transfer mode (S) shown first in Fig. 7 p At ), the voltage is the predefined maximum voltage (V m While it increases until it reaches the voltage value corresponding to ), the temperature increases, but the target temperature (T t It is maintained at less than ).

[0153] Target temperature (T t When approaching ), the output voltage decreases. In particular, when the determined temperature of the susceptor exceeds a threshold value or a preset percentage of the target temperature, the output voltage becomes a preset maximum voltage (V m It is set to a voltage lower than ). Therefore, the second power transfer mode (S of Fig. 7) p At ), the temperature of the susceptor (7) is the target temperature (T t As it approaches ), the boost voltage or output voltage decreases.

[0154] When the target temperature is reached, the power supply is set to a very low level. Therefore, the third power transfer mode (S) of FIG. 7 p In ), the output voltage value is reduced once again. Preferably, the output voltage is reduced to 8 V or less.

[0155] Of course, such power control is provided merely as an example. In another embodiment, even though the target temperature has been reached, the output voltage (V out ) is a predefined maximum voltage (Vm It can be maintained at ), and accordingly, may cause the susceptor temperature to overshoot. On the other hand, in safety mode, the output voltage (V out ) is always a predefined maximum voltage (V m It can be maintained lower than ).

[0156] In addition, other temperature control methods, that is, different from over-damping control, may also be used. For example, the temperature of the susceptor (7) may be controlled using rapid under-damping control, as shown in FIG. 8. In other words, the controller (9) is tuned to be under-damped. Under-damping would mean that the damping ratio is clearly less than 1. Thus, the controller (9) slightly overshoots to the target temperature (T t Reach ) faster.

[0157] In the example of FIG. 8, the controller (9) is configured to overshoot the temperature of the susceptor (7) for a short time period at the start of using the aerosol generating device, i.e., during warm-up. In the shown example, overshoot is reached in about 0.6 seconds.

[0158] Tuning the controller (9) to be under-damped improves the first puffing. In this rapid control, the first puffing is improved without breaking some physical limits. The physical limits may be, for example, that the tobacco does not burn or that the material of the aerosol generating device or its assembly does not deteriorate.

[0159] The determination of the susceptor (7) temperature can be based on the determined maximum value of the voltage across the capacitor of the coil circuit (61). For example, in the LLC circuit shown in FIG. 4a, the voltage across the capacitor (C) is each temperature identification mode (S Ti ) can be measured by the voltage sensor (63) during. Likewise, for example, in the LC circuit shown in FIG. 4b, the voltage across the capacitor (C2) is, for each temperature identification mode (S TiDuring this, it can be measured by a voltage sensor (64).

[0160] Each temperature identification mode (S Ti During ), resonant peak capacitor voltage detection is performed. The inverter (5) detects the minimum frequency (f) while the voltage across the capacitor is being measured. min ) and maximum frequency (f max It is controlled to sweep the frequency range between ). For example, the minimum frequency (f min ) can be approximately 350 kHz, and the maximum frequency (f max ) can be approximately 450 kHz. A frequency sweep can be performed at a specific resolution, where higher resolution means that voltage measurements are taken with a higher detection frequency within a specific frequency range, and vice versa. Voltage measurements from the voltage sensor (63 or 64) can be processed or conditioned before the peak voltage for each frequency is detected, for example, by multiplying the voltage measurement by a gain and / or by processing the voltage measurement to remove any DC offset so that only the AC signal is considered. Subsequently, the peak capacitor voltage for each frequency is detected using a high-speed peak detector. For example, V c1 is the maximum detected amount of capacitor voltage at frequency (f1), and V c2 is the maximum detected amount of capacitor voltage at frequency (f2), and V c3 is the maximum detected amount of capacitor voltage at frequency (f3), and all of these are f min and f max The same applies to all detection frequencies in between. This peak detection processing can be regarded as the extraction of a voltage envelope. Subsequently, using a known selection detection function, the global peak capacitor voltage is determined as the peak capacitor voltage (V). c1 , V c2 , Vc3 , ..., V cn Selected or chosen as the resonant capacitor voltage from ). The global peak capacitor voltage is selected from a specific temperature identification mode (S Ti It is the highest voltage among the peak capacitor voltages detected across all frequency sweeps.

[0161] Next, the temperature of the susceptor (7) can be determined using the global capacitor peak voltage (or resonant capacitor voltage). More specifically, the resonant capacitor voltage varies with temperature as shown in FIG. 9. A function equation describing the temperature of the susceptor (7) can be determined as a function of the capacitor voltage characteristics. A function equation describing the temperature of the susceptor (7) can also be determined as a function of the frequency at which the resonant capacitor voltage is obtained, that is, as a function of a specific frequency at which the highest peak capacitor voltage is measured during a frequency sweep.

[0162] Each temperature identification mode (S Ti During this process, the transistor (T0, T1) operates at a reduced duty cycle (D) of, for example, about 10% to 15%, thereby minimizing the heating of the susceptor (7).

[0163] Using the determined temperature of the susceptor (7), a subsequent power transfer mode (S p Induction heating can be adjusted during ).

[0164] It should be understood that various changes and modifications to the present preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the present disclosure and without diminishing the merits associated therewith. Accordingly, such changes and modifications will be covered by the appended claims.

[0165] For example, it can be understood that other functional equations can be used for the dependence between the resonance frequency and the temperature of the susceptor. For instance, non-linear functional equations, such as appropriately parameterized polynomial functions, can be used.

[0166] Accordingly, the present disclosure provides a method for controlling induction heating in an aerosol generating device capable of optimizing energy efficiency. Additionally, a desired temperature profile of the aerosol generating product can be obtained by adjusting the output voltage delivered to the vibration circuit.

[0167] Unless otherwise specified herein or clearly contradictory in the context, the present disclosure includes any combination of the aforementioned features of all possible variations.

[0168] Unless the context clearly requires otherwise, throughout the detailed description and claims, words such as “include,” “including,” etc., should be interpreted in an inclusive sense, that is, “includes, but is not limited thereto,” rather than in an exclusive or complete sense. Explanation of the symbols

[0169] 1 Aerosol generating device 2 main unit 3 cartridges First end of 30 cartridges 31 Second end of the cartridge 32 storage containers 33 Aerosol-generating products 4 batteries 40 battery circuits 5 inverters 50 Inverter Circuit Transistors of T0 and T1 inverters 6 Vibration Circuit 60 coils 61 Coil Circuit 62 Susceptor Circuit 63, 64 voltage sensor C1, C2 capacitors of the oscillating circuit f opOperating frequency f i Initial resonance frequency f r Resonance frequency 7 susceptors T d Determined temperature of the susceptor T t Target temperature of the susceptor 8 Boost Converter 80 boost converter circuit 81 Boost Converter Inductor 82 Boost Converter Capacitor 83 Current Sensor 84 voltage sensor 9 Controller Active switch of T2 boost converter Passive switch of the T3 boost converter V in Input voltage of the boost converter V out Output voltage of the boost converter S in Initialization step S p Power transfer mode S Ti Temperature identification mode

Claims

Claim 1 A method for controlling the heating of a susceptor (7) of an aerosol generating device (1) is provided, wherein the susceptor (7) is inductively heated by a vibration circuit (6) driven by an inverter (5), a boost converter (8) is connected between a power unit (4) and the inverter (5), and the boost converter (8) is supplied by an input voltage (V) supplied by the power unit (4). in ) output voltage (V) delivered to the inverter (5) out It is configured to increase the voltage to ), and the method is a power transfer mode (S) of the aerosol generating device (1). p ), and the amount of power supplied to the inverter (5) is the power transfer mode (S p Temperature identification mode (S) of the aerosol generating device (1) that is less than the amount of power supplied during ) Ti ) including, the method determines the temperature of the susceptor (7), and the determined temperature (T) of the susceptor (7). d According to ), the above power transfer mode (S p The output voltage (V) transferred from the boost converter (8) to the inverter (5) during ) out A method that additionally includes a step of setting ). Claim 2 In claim 1, the determination of the temperature of the susceptor (7) is based on the determined resonant frequency (f) of the vibration circuit (6). r A method based on ). Claim 3 A method according to claim 1 or 2, wherein the inverter (5) comprises two transistors (T0, T1), and the step of determining the temperature of the susceptor (7) comprises the following sub-steps: - operating only one of the two transistors (T0, T1) of the inverter (5); - the temperature identification mode (S Ti Among ) the resonance frequency (f) of the above vibration circuit (6) r A step of determining ); and- the determined resonant frequency (f r A step of determining the temperature (T) of the susceptor (7) based on ). Claim 4 In claim 1, the method of determining the temperature of the susceptor (7) is based on the determined maximum value of the display electric value of the vibration circuit (6). Claim 5 In paragraph 4, the above-mentioned electric value is a voltage across the capacitor of the vibration circuit (6). Claim 6 In claim 4 or 5, the step of determining the temperature of the susceptor (7) comprises the following sub-steps: - the temperature identification mode (S Ti A step of determining the maximum value of the display electric value of the vibration circuit (6) for a frequency range among; a step of determining the global maximum value from the determined maximum value; and a step of determining the temperature of the susceptor (7) based on the global maximum value. Claim 7 A method according to claim 4 or 5, wherein the inverter (5) comprises two transistors (T0, T1), and the step of determining the temperature of the susceptor (7) further comprises a substep of operating both of the two transistors (T0, T1) at a reduced duty cycle during the temperature identification mode. Claim 8 In any one of claims 1, 2, 4, and 5, during the operation of the aerosol generating device (1), the power transfer mode (S p ) and the above temperature identification mode (S Ti A method in which ) is performed alternately. Claim 9 In any one of claims 1, 2, 4, and 5, the temperature identification mode (S Ti ) is a method that runs at regular time intervals. Claim 10 In any one of claims 1, 2, 4, and 5, the determined temperature (T) of the susceptor (7) performed prior to the setting step. d ) target temperature (T t It includes a comparison step that compares with ), and the output voltage (V out ) is the above-determined temperature (T d ) and the above target temperature (T t A method that is set to a value depending on ). Claim 11 In item 10, the aerosol generating device, the temperature of the susceptor (7) is the target temperature (T t In order to make it ), the output voltage (V) of the boost converter (8) out It includes a controller (9) configured to control ), said controller (9) is tuned to be over-damped, and said output voltage (V out ) is a predefined maximum voltage (V) when the determined temperature of the susceptor is below a threshold value. m A method set to ). Claim 12 In Clause 11, the threshold value is the target temperature (T t A method in the range of 60% to 85% of ). Claim 13 In item 10, the aerosol generating device, the temperature of the susceptor (7) is the target temperature (T t In order to take the output voltage (V) of the boost converter (8) as ), out It includes a controller (9) configured to control ), said controller (9) is tuned to be under-damped, and said output voltage (V out ) is, when heating of the susceptor (7) starts, the temperature of the susceptor (7) is the target temperature (T t A method set to overshoot ). Claim 14 In paragraph 11, the above controller (9) is at least one of a PID controller, a model-based controller, and a model-predictive controller. Claim 15 In Clause 10, the above output voltage (V out ) is the determined temperature (T) of the susceptor (7). d ) is the above target temperature (T t A method in which, when equal to ), the voltage is set to be equal to or less than a predetermined voltage. Claim 16 A method in which, in any one of claims 1, 2, 4, and 5, the boost converter (8) is an asynchronous boost converter. Claim 17 A method according to any one of claims 1, 2, 4, and 5, wherein the boost converter is a synchronous boost converter. Claim 18 A method according to any one of claims 1, 2, 4, and 5, wherein the boost converter (8) includes an active switch (T2), and the active switch (T2) is a MOSFET transistor. Claim 19 In claim 17, the boost converter (8) includes a passive switch (T3), and the passive switch (T3) is a MOSFET transistor. Claim 20 In any one of claims 1, 2, 4, and 5, the boost converter (8) has an input voltage (V) in the range of 3 to 4.2 V. in From ) desired output voltage (V out A method configured to increase the voltage to ). Claim 21 An aerosol generating device (1) comprising: a power unit (4); an induction heating susceptor (7); a vibration circuit (6) arranged to generate a time-varying electromagnetic field for induction heating the susceptor (7); an inverter (5) configured to drive the vibration circuit (6); a boost converter (8) connected to the power unit (4) on one side and to the inverter (5) on the other side; and a controller (9) configured to implement a method for controlling the heating of the susceptor (7) according to any one of claims 1, 2, 4, and 5. Claim 22 delete Claim 23 delete Claim 24 delete Claim 25 delete Claim 26 delete Claim 27 delete Claim 28 delete Claim 29 delete Claim 30 delete Claim 31 delete Claim 32 delete Claim 33 delete Claim 34 delete Claim 35 delete Claim 36 delete Claim 37 delete Claim 38 delete Claim 39 delete Claim 40 delete Claim 41 delete Claim 42 delete

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