Resonant Frequency Tracking in Inductive Heater LCR Circuits
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Solution Overview
Problem
Existing aerosol generating devices using inductive heaters face challenges in accurately measuring temperature due to reliance on external sensors, which can be costly and prone to failure, and require significant heating times, posing safety concerns.
Innovation Solution
The method employs an Estimated Resonant Frequency (ERF) technique using inductive elements to estimate temperature by iteratively setting the frequency of the applied voltage, averaging output signals, and using polynomial fitting to determine the Actual Resonant Frequency (ARF), allowing for real-time temperature control without external sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external sensors are used to measure temperature, then temperature measurement accuracy is improved, but device cost increases and reliability decreases
Solution Approach 1:
The system uses the inductive heater circuit itself to measure temperature by monitoring resonant frequency changes, eliminating the need for separate temperature sensors. The heater circuit serves dual purposes: heating the susceptor and measuring its temperature through frequency drift detection.
Solution Approach 2:
The inductive heater circuit is designed to perform multiple functions: it heats the susceptor inductively and simultaneously measures temperature by detecting resonant frequency changes. This multi-functional approach replaces dedicated temperature sensing components.
2Measurement precision
If external sensors are used to measure temperature, then temperature measurement accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The inductive heater circuit measures its own operational parameters by monitoring its own resonant frequency, eliminating the need for external measurement sensors and reducing overall device complexity.
Solution Approach 2:
The same circuit components used for inductive heating are also used for temperature measurement, reducing the total component count and simplifying the device architecture.
3Productivity
If heating power is increased to reduce heating time, then productivity is improved, but electrical stress on the device increases
Solution Approach 1:
The system continuously monitors resonant frequency changes and adjusts the drive frequency to maintain optimal heating conditions. This feedback mechanism allows efficient heating at reduced power levels by preventing energy loss from operating away from resonance.
Solution Approach 2:
The drive frequency is dynamically adjusted to track the changing resonant frequency of the heater circuit as the susceptor heats up, maintaining optimal heating efficiency throughout the heating process and reducing overall electrical stress.
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 provides accurate temperature measurement and control, reducing electrical stress on the device, prolonging its life, and enabling efficient heating of susceptors made from materials like aluminum foils, while avoiding the need for external sensors.
Implementation Method 1
inductive heaters heat an aerosol generating substrate such as tobacco to form an aerosol
Implementation Method 2
Common devices use inductive heaters to create an aerosol from a suitable medium
Implementation Method 3
determine a resonant frequency of the RLC resonance circuit, and determine, based on the determined resonant frequency
Data Source
Figure 1
Figure 2(a)~2(b)
Figure 2(c)
AI summary
A method comprising: providing an LCR circuit comprising an inductive element and a capacitor, and applying a voltage to the LCR circuit, wherein the applied voltage induces a response between the capacitor and the inductive element of the LCR circuit, determining a plurality of resonant frequencies for the response at a plurality of times, respectively; generating an output signal of the response and selecting a resonant frequency from the plurality of resonant frequency based on the output signal wherein setting the frequency of the applied voltage is selected dependent on the selected resonant frequency and then repeating the steps outlined above.