Inductive Heating Duty Cycle Control During Susceptor Cooling Events
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Solution Overview
Problem
Inductive heating arrangements in aerosol-generating systems face challenges in accurately monitoring and controlling the temperature of the susceptor, particularly during user puffs or other cooling events, which can lead to overheating.
Innovation Solution
A method of controlling an inductive heating arrangement by providing pulses of electrical current to maintain a target conductance or resistance of the susceptor, detecting cooling events, and increasing the duty cycle of the pulses within a maximum duty cycle limit to compensate for the cooling event, thereby preventing overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the duty cycle of electrical current pulses is increased to compensate for cooling events during user puffs, then the temperature control accuracy is improved, but the risk of overheating increases
Solution Approach 1:
The patent applies dynamics by making the duty cycle adjustable and adaptive rather than fixed. The control system dynamically modifies the duty cycle based on real-time detection of cooling events (such as user puffs) while incorporating a maximum duty cycle limit to prevent excessive heating. This dynamic adjustment allows the system to respond to changing thermal conditions without exceeding safe temperature thresholds.
Solution Approach 2:
The patent implements feedback mechanisms by monitoring temperature or resistance changes of the susceptor in real-time and using this information to adjust the duty cycle of electrical current pulses. The system detects cooling events through changes in susceptor temperature or resistance and compensates by increasing power delivery within safe limits, creating a closed-loop control system that balances temperature accuracy with overheating prevention.
2Reliability
If real-time temperature monitoring is implemented to prevent overheating, then the safety is improved, but the device complexity increases
Solution Approach 1:
The patent replaces direct physical contact temperature sensors with an electrical measurement approach. By monitoring changes in the electrical resistance or impedance of the susceptor itself, the system infers temperature without requiring separate sensing hardware. This substitution reduces device complexity while maintaining safety through effective temperature monitoring.
Solution Approach 2:
The susceptor serves dual functions: it is both the heating element and the temperature sensor. The susceptor's inherent electrical properties (resistance or impedance) change with temperature, allowing the system to monitor its own temperature state without external sensing components. This self-service approach simplifies the overall system architecture while enabling reliable temperature-based safety control.
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
The method effectively prevents overheating of the susceptor during cooling events by dynamically adjusting the power supply based on real-time temperature monitoring, ensuring optimal aerosol generation and delivery.
Implementation Method 1
The inductor generates an alternating magnetic field that causes heating in the susceptor
Implementation Method 2
inductive heating arrangement comprising a susceptor and at least one inductor coupled to the susceptor so that the provision of an alternating electrical current to the inductor causes heating of the susceptor
Implementation Method 3
heat is transferred from the susceptor to the aerosol-forming substrate primarily by conduction
Data Source
Figure 1~2B
Figure 3
Figure 4~5
AI summary
A method of controlling an inductive heating arrangement is provided. The inductive heating system comprising an inductor and a susceptor coupled to the inductor so that the provision of an alternating electrical current to the inductor causes heating of the susceptor. The method comprises: providing pulses of electrical current to the at least one inductor to maintain a conductance or resistance associated with the susceptor at a target conductance or resistance; detecting a cooling event associated with the susceptor; determining a maximum duty cycle limit for the pulses of electrical current for a duration of the cooling event; and increasing a duty cycle of the pulses of electrical current for the duration of the detected cooling event, to compensate for the detected cooling event, to a duty cycle at or below the maximum duty cycle limit.