Hot Wire Anemometer Control for Accurate Puff Detection
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Solution Overview
Problem
Existing non-nicotine electronic vaping devices lack effective methods for accurately detecting inhalation puffs and controlling the power to the hot wire anemometer (HWA) based on temperature changes, which affects the precision of airflow measurement and puff detection.
Innovation Solution
Implementing a first PID controller to control power to the HWA based on temperature setpoints and a second PID controller to adjust temperature setpoints in response to ambient temperature changes, while generating a puff detection signal and determining airflow rates using pulse width modulation (PWM) drive signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single PID controller is used to control HWA power, then the control system is simple, but puff detection accuracy and airflow measurement precision deteriorate due to inability to distinguish ambient temperature changes from actual puff events
Solution Approach 1:
The control system is segmented into two independent PID controllers: a first PID controller that manages HWA power based on temperature setpoints, and a second PID controller that detects ambient temperature changes and adjusts the temperature setpoint accordingly. This segmentation allows each controller to specialize in its function, improving overall measurement precision without excessive complexity
Solution Approach 2:
The temperature setpoint acts as an intermediary between the second PID controller (ambient temperature detection) and the first PID controller (HWA power control). By mediating through the setpoint parameter, the system can compensate for ambient temperature drifts without directly interfering with the primary control loop, thereby maintaining puff detection accuracy
2Device complexity
If the temperature setpoint is fixed, then the control algorithm is simple, but measurement precision deteriorates when ambient temperature changes occur
Solution Approach 1:
The second PID controller performs preliminary detection of ambient temperature changes and proactively adjusts the temperature setpoint before these changes significantly affect the HWA operation. This preliminary action ensures that the temperature baseline remains accurate even in varying environmental conditions, maintaining measurement precision
Solution Approach 2:
The second PID controller continuously monitors the relationship between the drive signal setting value and its setpoint, detecting ambient temperature changes through this feedback mechanism. This feedback loop dynamically adjusts the temperature setpoint to compensate for environmental variations, improving airflow measurement precision
3Use of energy by moving object
If power to HWA is not precisely controlled, then energy consumption is lower, but puff detection accuracy and airflow measurement precision deteriorate
Solution Approach 1:
The first PID controller dynamically adjusts the power delivered to the HWA based on real-time temperature measurements and the temperature setpoint. This dynamic control ensures the HWA operates at the optimal power level for accurate puff detection and airflow measurement, rather than using fixed high power that would waste energy
Solution Approach 2:
The system changes the operating parameters of the HWA by adjusting power delivery through PWM control based on temperature feedback. By optimizing the power parameter according to actual thermal conditions and detection requirements, the system achieves high measurement precision while minimizing unnecessary energy consumption
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
Enhances the accuracy of puff detection and airflow measurement by precisely controlling power to the HWA, improving the overall performance of non-nicotine e-vaping devices.
Implementation Method 1
a hot wire anemometer (HWA) in fluid communication with the mouthpiece and configured to measure a flow rate of air flowing around the HWA
Implementation Method 2
a heater configured to generate a non-nicotine vapor by heating the non-nicotine pre-vapor formulation
Data Source
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AI summary
A method of controlling a hot wire anemometer (HWA) of a non-nicotine e-vaping device includes controlling, by a first PID controller, a level of power applied by the non-nicotine e-vaping device to the HWA based on a temperature of a heated element of the HWA and a temperature setpoint; generating a puff detection signal indicating whether or not a puff is currently occurring with respect to the non-nicotine e-vaping device; and while the puff detection signal indicates that a puff is not currently occurring with respect to the non-nicotine e-vaping device, detecting, by a second PID controller, a change in an ambient temperature of the HWA, and controlling, by the second PID controller, the temperature setpoint such that the temperature setpoint changes in response to the detected change in the ambient temperature of the HWA.