Induction Hob Boil Detection Using Fixed-Frequency Gradient Sensing
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Solution Overview
Problem
Existing boil detection methods for induction hobs are not accurate due to detrimental influences that lead to incorrect boil point detection results.
Innovation Solution
A method that disables the power control mechanism, measures and interpolates electrical parameters like coil peak current or phase delay, calculates a gradient measure, and determines the boil point based on the gradient, while adapting criteria and thresholds to account for temperature changes and cookware properties, and compensates for mains voltage fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the power control mechanism is disabled and frequency is fixed for boil detection, then measurement precision of boil point is improved, but the output power may drop excessively at the beginning of cooking process
Solution Approach 1:
The system performs preliminary heating with power control active for a delay period before disabling it for boil detection. This preliminary action ensures the cookware reaches a temperature where boil detection becomes reliable, while avoiding the excessive power drop that would occur if detection started immediately.
Solution Approach 2:
The system dynamically transitions between two operational modes: initially maintaining power control for sufficient heating, then switching to fixed-frequency detection mode. This dynamic adaptation allows the system to optimize both power delivery and measurement precision at different stages of the cooking process.
2Reliability
If electrical parameters are measured without interpolation, then response time is reduced, but noise interference increases leading to false detections
Solution Approach 1:
The system applies interpolation to a limited extent - using a time window that gathers multiple parameter values and calculates their average. This partial application of smoothing reduces noise interference and false detections while maintaining sufficiently fast response time for practical boil detection.
3Measurement precision
If the time window for interpolating electrical parameters is increased, then noise interference is reduced improving detection accuracy, but the response time to detect boil point is delayed
Solution Approach 1:
The system uses a moderate time window size that collects enough samples to reduce noise through averaging, but not so large as to significantly delay boil point detection. This partial application of the interpolation technique balances accuracy improvement against response time loss.
Solution Approach 2:
The system optimizes the time window parameter to achieve the best compromise between noise reduction and response speed. By carefully selecting the window duration, the system maximizes measurement accuracy while minimizing the delay in detecting when boiling occurs.
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 a robust and reliable boil detection method by reducing noise interference and accurately determining the boil point, avoiding false detections and extending the usability of cookware with varying inductive properties.
Implementation Method 1
the induction coil is coupled with electronic driving means for driving an AC current through the induction coil. Said AC current generates a time verifying magnetic field. Due to the inductive coupling between the inductor coil and the piece of cookware placed on the induction hob, the magnetic field generated by the inductor coil causes eddy currents circulating in the piece of cookware. The presence of said eddy currents generates heat within the piece of cookware due to the electrical resistance of said piece of cookware.
Implementation Method 2
the magnetic field generated by the inductor coil causes eddy currents circulating in the piece of cookware
Implementation Method 3
The presence of said eddy currents generates heat within the piece of cookware due to the electrical resistance of said piece of cookware
Data Source
AI summary
The invention relates to a method for boil detection at a heating zone of an induction hob (1), the method comprising the steps of: —disabling (S110) a power control mechanism of the induction hob by setting the frequency of the AC-current provided to an induction coil of the induction hob to a fixed value; —measuring (S120) values of an electrical parameter provided within the induction hob (1); —interpolating (S130) the measured electrical parameter values by gathering a plurality of values of the electrical parameter within a time window and calculating the average value of said gathered plurality of values thereby obtaining interpolated electrical parameter values. —calculating (S140) a gradient measure indicative for the differential change of the interpolated electrical parameter values over time; —determining (S150) the boil point based on the calculated gradient measure.