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EP-4494424-B1 - A METHOD FOR CONTROLLING THE HEATING OF A SUSCEPTOR OF AN AEROSOL-GENERATING DEVICE

EP4494424B1EP 4494424 B1EP4494424 B1EP 4494424B1EP-4494424-B1

Inventors

  • PILATOWICZ, Grzegorz Aleksander
  • GARCIA GARCIA,, Eduardo Jose

Dates

Publication Date
20260506
Application Date
20230302

Claims (15)

  1. A method for controlling the heating of a susceptor (7) of an aerosol-generating device (1), the susceptor (7) being inductively heated by an oscillating circuit (6) driven by an inverter (5), wherein the method comprises a pre-heating phase (PHP) of the aerosol-generating device (1) and a subsequent heating phase (HP) of the aerosol-generating device (1), a step of estimating or determining a temperature of the aerosol-generating device (1) being performed during the pre-heating and heating phases (PHP, HP), wherein at the start of the pre-heating phase (PHP), the estimation or determination of the temperature is based on a determined resonant frequency of the oscillating circuit (6) or a determined indicative electrical value of the oscillating circuit (6), and characterised in that the determination or estimation of the temperature is transitioned to being based on a measured internal temperature of the aerosol-generating device (1).
  2. A method according to claim 1, wherein the estimation or determination of the temperature is transitioned when the rate of change of the estimated or determined temperature falls below a first predefined value, e.g., about 3 to about 7°C/s.
  3. A method according to claim 1 or claim 2, wherein, after the initial transition, the estimation or determination of the temperature is based on a measured internal temperature of the aerosol-generating device until the end of the heating phase (HP).
  4. A method according to claim 1 or claim 2, wherein, after the initial transition, the estimation or determination of the temperature is transitioned to being based on a determined resonant frequency of the oscillating circuit (6) or a determined indicative electrical value of the oscillating circuit (6) if the rate of change of the estimated or determined temperature exceeds a second predefined value e.g., about 8 to about 12°C/s.
  5. A method according to any preceding claim, wherein the estimation or determination of the temperature at the start of the pre-heating phase (PHP) is based on a determined resonant frequency of the oscillating circuit (6), and wherein the resonant frequency is determined by measuring the phase angle between the current of an inductance coil (60) and the voltage of a capacitor of the oscillating circuit (6), the resonant frequency corresponding to the frequency when the phase angle is substantially equal to 90°.
  6. The method according to any of claims 1 to 4, wherein the estimation or determination of the temperature at the start of the pre-heating phase (PHP) is based on a determined resonant frequency of the oscillating circuit (6), and wherein the resonant frequency is determined by minimizing an error function calculated using measurements of electrical indicative values in the oscillating circuit (6).
  7. A method according to any preceding claim, wherein the estimated or determined temperature of the aerosol-generating device (1) is the temperature of the susceptor (7).
  8. The method according to claim 7, wherein the estimation or determination of the temperature at the start of the pre-heating phase (PHP) is based on a determined resonant frequency of the oscillating circuit (6), and wherein the temperature of the susceptor (7) is estimated or determined using a predefined linear or polynomial function between the resonant frequency of the oscillating circuit (6) and the temperature of the susceptor (7).
  9. The method according to any of claims 1 to 4, wherein the estimation or determination of the temperature at the start of the pre-heating phase (PHP) is based on an indicative electrical value of the oscillating circuit (6).
  10. The method according to any preceding claim, wherein the determination or estimation of the temperature is transitioned to being based on a measured internal temperature of the aerosol-generating device (1) and a predefined offset.
  11. A method according to any preceding claim, wherein the estimated or determined temperature of the aerosol-generating device (1) is used to control the heating of the susceptor (7) during the pre-heating and heating phases (PHP, HP).
  12. A method according to claim 11, wherein heating of the susceptor (7) is controlled based on a comparison between the estimated or determined temperature and a target temperature or temperature profile.
  13. A method according to claim 11 or claim 12, wherein the aerosol-generating device (1) further comprises a power converter (8) connected between a power supply unit (4) and the inverter (5), and wherein the estimated temperature is used to vary the output voltage of the power converter (8) or to control the operation of the inverter (5).
  14. An aerosol-generating device (1) comprising: an induction heatable susceptor (7); an oscillating circuit (6) arranged to generate a time varying electromagnetic field for inductively heating the susceptor (7); an inverter (5) configured to drive the oscillating circuit (6); a temperature sensor (21) for providing internal temperature measurements of the aerosol-generating device (1); and a controller (9) adapted to implement the method for controlling the heating of the susceptor (7) according to any one of claims 1 to 13.
  15. An aerosol-generating device (1) according to claim 14, further comprising a power converter (8) connected between a power supply unit (4) and the inverter (5).

Description

Technical Field The present disclosure relates generally to a method for controlling the heating of a susceptor of an aerosol-generating device and an aerosol-generating device comprising a controller adapted to implement said method. Technical Background An aerosol-generating device generally comprises at least one reservoir arranged to store an aerosol-generating (or vaporizable) material which can be a solid or a liquid. The aerosol-generating material is heated, without burning, in order to generate an aerosol for inhalation. The aerosol is released into a flow path extending between an inlet and outlet of the device. The outlet may be arranged as a mouthpiece, through which a user inhales for delivery of the aerosol. In some aerosol-generating devices, the aerosol-generating material is stored in a removable cartridge. Thus, when the aerosol-generating material is consumed, the cartridge can be easily removed and replaced. The aerosol-generating material can be heated using different methods. One method consists in using induction heating. Such an aerosol-generating device thus comprises an induction heating system usually comprising an induction coil, an induction heatable susceptor and a power supply unit. Thanks to the power supply unit or battery, electrical energy is provided to the induction coil. The induction coil thus generates an alternating electromagnetic field. The susceptor couples with the electromagnetic field and generates heat, which is transferred, for example by conduction, to the aerosol-generating material. Finally, the heated aerosol-generating material generates an aerosol. For an optimized operating of the aerosol-generating device, there is a need to seek the highest possible energy efficiency during inductive heating. The present disclosure aims at providing an improved method for controlling the inductive heating of a susceptor of an aerosol-generating device. More precisely, it aims at improving the energy efficiency when heating the susceptor. The method of the present disclosure further aims to ensure a consistent and high-quality vaping experience for the user of the aerosol-generating device. The heating system of the aerosol-generating device should be able to heat the aerosol-generating material without burning it. Additionally, in order to provide a better user experience, the aerosol-generating material can be heated according to a predefined heating profile. Accurate temperature control is crucial for heating in an aerosol-generating device. The aerosol-generating material can, for example, be heated too slowly or on the contrary, too fast. This can burn the aerosol-generating material and/or provide a poor user experience. The present disclosure aims to provide optimal temperature estimation during different operating phases of the aerosol-generating device, and in particular during an initial pre-heating phase and subsequent heating phase. JP 7 035248 discloses a method according to the preamble of claim 1. Other methods for controlling heating are disclosed in US 2021/169146 and WO 2020/223350. Summary of the Disclosure According to a first aspect of the present disclosure, there is provided a method for controlling the heating of a susceptor of an aerosol-generating device according to claim 1. At the start of the pre-heating phase, the estimation or determination of the temperature is based on a determined resonant frequency of the oscillating circuit or a determined indicative electrical value of the oscillating circuit (i.e., estimation or determination of the temperature of the aerosol-generating device is based on a determined "parameter of the oscillating circuit" at the start of the pre-heating phase), and the estimation or determination of the temperature is then subsequently transitioned to being based on a measured internal temperature of the aerosol-generating device. The indicative electrical value can be any value that is a function of, or is related or proportional to, the resonant frequency of the oscillating circuit or the operating frequency at which the inverter is driving the oscillating circuit. The indicative electrical value can be for example a current, a voltage or an impedance. The indicative electrical value can be the voltage of a capacitor of the oscillating circuit, for example. The indicative electrical value can be determined using sensors, such as a voltage or current sensor. The pre-heating phase is generally intended to pre-heat aerosol-generating material (or vaporizable material) stored in the aerosol-generating device, e.g., in a storage portion or compartment of the aerosol-generating device, and the heating phase is generally intended to heat the aerosol-generating material to generate aerosol. At the start of the pre-heating phase, temperature estimation or determination is initially based on a determined parameter of the oscillating circuit. This provides accurate temperature estimation or determination during highly dyn