Induction Cooktop Control Unit Detects Cookware Position
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Solution Overview
Problem
Existing induction heating cooktops using single switch quasi-resonant circuits face challenges in detecting cookware position and characteristics under variable mains voltage and temperature conditions, leading to inefficient heating and potential damage to electronic circuits.
Innovation Solution
A control unit with a current detection circuit, comprising a current detection resistor or transformer, monitors the diode conduction time to determine the presence and alignment of cookware on the induction coil, interrupting power if misalignment or absence is detected, ensuring safe and efficient energy transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If single switch quasi-resonant circuits are used for cost advantage, then device complexity is reduced, but measurement precision of cookware position and characteristics deteriorates under variable mains voltage and temperature conditions
Solution Approach 1:
The patent implements a feedback mechanism by continuously monitoring the diode conduction time and comparing it with reference values stored in memory. The control unit adjusts the heating process based on this feedback, allowing accurate cookware detection despite using a simpler single switch quasi-resonant circuit topology.
Solution Approach 2:
The patent changes the monitoring parameter from resonance voltage (which is sensitive to voltage fluctuations) to diode conduction time. This parameter transformation makes the detection system more robust against variable mains voltage and temperature conditions while maintaining measurement precision.
2Device complexity
If resonance voltage comparison with fixed reference voltage is used for vessel detection, then device complexity is reduced, but reliability of detection deteriorates under variable mains voltage conditions
Solution Approach 1:
The patent transforms the detection parameter from resonance voltage to diode conduction time. This parameter change eliminates the sensitivity to mains voltage variations, as the conduction time is determined by the resonant circuit's natural frequency and the fixed switching frequency, not by the absolute voltage level.
Solution Approach 2:
The patent replaces the voltage-based detection mechanism with a time-based detection mechanism. Instead of measuring voltage amplitude (which varies with mains voltage), the system measures the duration of diode conduction, which is a temporal parameter less susceptible to voltage fluctuations.
3Adaptability or versatility
If multi coil - multi zone structure is used for heating flexibility, then adaptability is improved, but difficulty of detecting and measuring cookware characteristics increases under variable voltage and temperature conditions
Solution Approach 1:
The patent divides the cooktop into multiple independent heating zones, each with its own induction coil and control unit. This segmentation allows independent detection and control of each zone, simplifying the overall detection task compared to a single large zone while maintaining flexibility.
Solution Approach 2:
Each heating zone implements independent feedback-based detection using diode conduction time monitoring. This allows the system to accurately detect cookware presence and position in each zone separately, managing the complexity through modular independent detection systems.
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 solution enables reliable detection of cookware position and alignment across varying voltage and temperature conditions, preventing damage to electronic components and ensuring efficient heating in multi-zone induction heating cooktops.
Implementation Method 1
The induction heating cooktop functions according to the principle of heating a cast iron or steel ferromagnetic cookware, for example a pot, with the magnetic field effect generated by the induction coil
Implementation Method 2
a resonant circuit having an induction coil that provides the heating of the vessel placed thereon and a resonant capacitor connected in parallel to the induction coil
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The present invention relates to an induction heating cooktop (1) comprising a resonant circuit (6) having an induction coil (4) and a resonant capacitor (5) connected in parallel to the induction coil (4), a power switch (7), for example an IGBT, that drives the resonant circuit (6), a freewheeling diode (8) connected in parallel to the power switch (7), a collector node (9) whereon resonance voltage (Vce) is generated during the non-conduction (turn-on) times of the power switch (7), a drive circuit (10) that provides the power switch (7) to be driven, and a control unit (11) that regulates the operation of the power switch (7) by controlling the drive circuit (10), and wherein the presence of the vessel (K) placed on the induction coil (4) and appropriate position thereof is determined under variable mains voltage and temperature conditions.