Electrical Heater Pulse Control for Aerosol Temperature Limiting
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Solution Overview
Problem
Electrically heated smoking systems face challenges in maintaining consistent aerosol delivery over time and preventing overheating, which can lead to combustion of the aerosol-forming substrate, especially under extreme conditions, and existing control methods like PID control are computationally expensive and prone to overshoot.
Innovation Solution
A method and device that control the electrical heater by providing different time periods for power supply based on the excess temperature, allowing for rapid temperature adjustments by varying the target temperature and power pulses, without the need for separate temperature sensors, using electrical resistance as a parameter to manage power delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If PID control is used to control heater temperature, then temperature control accuracy is improved, but computational complexity increases and response time slows down
Solution Approach 1:
The patent replaces the complex PID control algorithm with a simple lookup table containing pre-calculated duty cycle values. This lookup table acts as a 'cheap' control mechanism that provides sufficient temperature control accuracy without the computational overhead of PID calculations, effectively discarding the complex algorithm in favor of a simpler alternative.
Solution Approach 2:
The patent pre-calculates and stores optimal duty cycle values in a lookup table based on desired temperature profiles. This preliminary action allows the controller to quickly retrieve appropriate duty cycle values during operation without performing real-time complex calculations, thereby reducing computational complexity while maintaining control accuracy.
2Stability of the object's composition
If target temperature falls abruptly to produce consistent aerosol, then aerosol consistency is improved, but temperature control response speed must increase
Solution Approach 1:
The patent uses periodic duty cycle adjustments based on the lookup table to control the heater. By periodically updating the duty cycle according to pre-calculated values corresponding to the desired temperature profile, the system can rapidly respond to temperature changes including abrupt target temperature falls, thereby achieving both aerosol consistency and fast response speed.
Solution Approach 2:
The patent replaces the mechanical/continuous PID control system with an electronic lookup table-based control system. This substitution allows for instantaneous retrieval of control parameters, enabling rapid response to temperature profile changes without the lag inherent in continuous computational control methods.
3Productivity
If continuous heating is applied to maintain temperature, then aerosol delivery is maintained, but risk of overheating and combustion increases
Solution Approach 1:
The patent implements feedback control by monitoring the actual heater temperature and using this information to adjust the duty cycle according to the lookup table. This feedback mechanism ensures that heating is applied continuously only when necessary to maintain the desired temperature profile, preventing overheating and combustion while maintaining aerosol delivery.
Solution Approach 2:
The patent uses dynamic duty cycle adjustment based on the lookup table, which provides different duty cycle values at different times during the heating process. This dynamic control allows the system to apply heating continuously when needed to maintain aerosol delivery while reducing or stopping heating when the temperature profile indicates it is safe, thereby preventing overheating and combustion.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables rapid and responsive temperature control, preventing overheating and ensuring consistent aerosol delivery by adjusting power supply periods and pulse duty cycles, thus maintaining the aerosol quality and preventing substrate combustion.
Implementation Method 1
electrically heated smoking systems... heating element or elements in the device... supplying pulses of electrical current to the heating element
Implementation Method 2
monitoring the duty cycle of the pulses of electrical current... measured parameter, indicative of the temperature of the heater
Data Source
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AI summary
There is provided method and system for controlling heating in an aerosol-generating system(100) comprising a heater(14). The method comprises comparing a measured parameter (R), indicative of the temperature of the heater(14), with a target value (Rtarget) for that parameter; if the measured parameter (R) exceeds the target value(Rtarget) by greater than or equal to a first amount, then preventing a supply of power to the heater(14) for a first time period; and if the measured parameter exceeds the target value, but by less than the first amount, then preventing the supply of power to the heater for a second time period, shorter than the first time period. This allows for rapid cooling of the heater when necessary.