Detection of adverse heater conditions in an electrically heated aerosol generating system

1. An electrically operated aerosol-generating system, comprising:

a heating element configured to heat an aerosol-forming substrate;

a power supply configured to supply power to the heating element;

a temperature sensor configured to sense a temperature at the heating element;

electric circuitry, in communication with the heating element, the temperature sensor, and the power supply, the electric circuitry comprising a memory and being configured to:

regulate a supply of power to the heating element based on a measured temperature from the temperature sensor,

determine an adverse condition when a reduction in power supplied to the heating element required to reach or to maintain a predetermined temperature over successive heating cycles falls outside a predefined range, by comparing the minimum power supplied to the heating element during a temperature maintenance phase in a given heating cycle with that supplied in one or more preceding heating cycles so as to obtain a difference between the minimum powers as the reduction in power, the predefined range being stored in the memory, and

control the power supplied to the heating element based on whether there is the adverse condition or provide an indication when there is the adverse condition; and

a device and a removable cartridge,

wherein the power supply and the electric circuitry are in the device and the heating element is in the removable cartridge, and

wherein the cartridge comprises a liquid aerosol-forming substrate.

2. The electrically operated aerosol-generating system according to claim 1 , wherein the electric circuitry is further configured to determine the adverse condition only after the temperature at the heating element has risen from an initial temperature to a target temperature.

3. The electrically operated aerosol-generating system according to claim 1 , wherein the predefined range is based on a maximum threshold value of a rate of change in power supplied or a minimum threshold value of reduction in power supplied over the successive heating cycles.

4. The electrically operated aerosol-generating system according to claim 1 , wherein the temperature sensor is further configured to measure electrical resistance of the heating element.

5. The electrically operated aerosol-generating system according to claim 1 ,

further comprising a puff detector configured to detect when a user is puffing on the system,

wherein the puff detector is in communication with the electric circuitry, and

wherein the electric circuitry is further configured to

supply power from the power supply to the heating element when a puff is detected by the puff detector so that each puff corresponds to a heating cycle, and

determine if there is the adverse condition during each heating cycle.

6. The electrically operated aerosol-generating system according to claim 1 , wherein the electric circuitry is further configured to cease the supply of power to the heating element in response to determining an adverse condition.

7. The electrically operated aerosol-generating system according to claim 1 , wherein the heating element comprises a mesh.

8. The electrically operated aerosol-generating system according to claim 7 , wherein the mesh comprises interstices having a width of between 10 μm and 100 μm.

9. The electrically operated aerosol-generating system according to claim 1 , wherein the heating element is arranged to circumscribe at least a portion of the cartridge.

10. The electrically operated aerosol-generating system according to claim 1 , wherein the cartridge comprises a capillary wick configured to transport the liquid aerosol-forming substrate to the heating element.

11. The electrically operated aerosol-generating system according to claim 1 , further comprising a mouthpiece configured for engagement with the device or the cartridge.

12. A method of controlling a supply of power to a heating element in an electrically operated aerosol-generating system, comprising:

measuring a temperature at a heating element;

regulating the supply of power to the heating element based on the measured temperature;

determining an adverse condition when a reduction in power supplied required to reach or to maintain a predetermined temperature over successive heating cycles falls outside a predefined range, by comparing the minimum power supplied to the heating element during a temperature maintenance phase in a given heating cycle with that supplied in one or more preceding heating cycles so as to obtain a difference between the minimum powers as the reduction in power, the predefined range being stored in a memory of electric circuitry; and

controlling the power supplied to the heating element based on whether there is the adverse condition or providing an indication when there is the adverse condition.

13. A nontransitory computer-readable storage medium having a computer program stored thereon that when executed on an internal memory of a microprocessor comprising software code portions in an electrically operated aerosol-generating system, causes the microprocessor to perform the method according to claim 12 , the electrically operated aerosol-generating system comprising a heating element configured to heat an aerosol-forming substrate, a sensor configured to sense a temperature of the heating element, and a power supply configured to supply power to the heating element, the microprocessor being connected to the electric heater, the sensor, and the power supply.