Induction Coil Temperature Gradient Detection
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Solution Overview
Problem
Existing methods for determining the boiling point of water in a cooking vessel on an induction hob are inaccurate due to temperature differences within the vessel and the rapid formation of vapor bubbles, leading to incomplete heating.
Innovation Solution
A method utilizing individually controllable induction heating coils, where one coil operates as a measuring coil to detect the vibration response and temperature gradient, allowing for precise determination of boiling by switching to a low-power measurement mode to avoid heating-induced inaccuracies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If induction heating coils operate at high power to heat water quickly, then heating speed is improved, but temperature measurement accuracy deteriorates due to heating-induced temperature gradients and vapor bubble formation
Solution Approach 1:
The system divides the heating process into distinct phases: a heating phase where multiple coils operate at high power to heat water quickly, and a measurement phase where one coil operates at low power to accurately detect boiling. This temporal segmentation allows both high heating speed and accurate temperature measurement to be achieved at different times.
Solution Approach 2:
The system applies different power levels to different heating coils based on their functional role. One coil (the measuring coil) operates at low power to provide accurate temperature measurement, while other coils continue to operate at high power to maintain overall heating efficiency. This local differentiation of power quality resolves the contradiction between heating speed and measurement accuracy.
2Productivity
If multiple induction heating coils operate simultaneously at high power, then overall heating efficiency is improved, but temperature uniformity deteriorates due to temperature differences within the vessel
Solution Approach 1:
The system uses feedback from the measuring coil's detection of boiling conditions to control the operation of other heating coils. When boiling is detected, the system can adjust or stop heating from other coils to prevent overheating and maintain temperature uniformity, while still achieving high overall heating efficiency through the coordinated operation of multiple coils.
3Measurement precision
If temperature measurement is performed continuously during heating, then temperature determination accuracy is improved, but energy consumption increases due to prolonged high-power operation
Solution Approach 1:
The system performs temperature measurement periodically by switching the measuring coil to low-power measurement mode at specific intervals during the heating process, rather than maintaining continuous high-power operation. This periodic measurement approach achieves accurate temperature determination while minimizing energy consumption by limiting the duration of high-power heating.
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 ensures accurate temperature determination by minimizing heat output during measurement, reducing temperature differences within the vessel, and preventing premature boiling over, thus ensuring all water reaches the desired temperature.
Implementation Method 1
each induction heating coil heats the area of the cookware base above it
Implementation Method 2
The energy is transferred to the lowest part of the cookware base
Implementation Method 3
the vibration response of at least one induction heating coil is used to detect whether the temperature of the cooking vessel base above this coil is changing or increasing. In this way, a temperature gradient of the cooking vessel base can be detected by the induction heating coil
Data Source
Figure 1~3
Figure 4
AI summary
To determine the temperature of boiling water on an induction cooktop with multiple individually controllable induction heating coils, which together form a single cooking zone for a pot of water, a pot of water is placed over at least two induction heating coils. The induction heating coils are operated in heating mode to bring the water in the pot to a boil, and each coil heats the area of the pot's base directly above it. During heating, the oscillation response of each induction heating coil is used to detect whether the temperature of the pot's base above that coil is rising. The induction heating coils remain in heating mode at least until one coil detects that the temperature gradient of the pot's base above it reaches zero.It is then configured as a measuring coil and operated in measurement mode with low measuring power, no longer in heating mode. If the time-dependent temperature gradient of its coil becomes zero, the water in the cooking vessel is determined to be boiling.