Induction Cooker Magnetic Saturation Detection via Multi-Parameter Monitoring
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Solution Overview
Problem
Existing induction cookers face challenges in reliably detecting the onset of magnetic saturation in the induction coil, leading to potential unsafe conditions due to rapid changes in inductance and current levels.
Innovation Solution
A method and system that measure and compare the inductance, current, and conduction time of semiconductor switches with predetermined threshold values to determine if magnetic saturation has occurred, triggering the termination of current supply to the induction coil through a cyclic monitoring process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single threshold-based detection method is used to detect magnetic saturation, then the detection process is simple, but the reliability of detection is insufficient leading to potential unsafe conditions
Solution Approach 1:
The detection system is segmented into three independent detection channels: inductance detection, current detection, and conduction time detection. Each channel monitors a specific parameter and compares it against predetermined thresholds. This segmentation allows the system to achieve high reliability through multiple independent checks while keeping each individual detection module simple and manageable.
Solution Approach 2:
The controller is designed to perform multiple functions: it controls the semiconductor switches, measures inductance, measures current, measures conduction time, and makes termination decisions. By integrating these multiple functions into a single controller, the system achieves reliable multi-parameter monitoring without requiring separate dedicated devices for each function, thus balancing reliability with controlled complexity.
2Measurement precision
If continuous monitoring of multiple parameters is performed, then detection accuracy is improved, but energy consumption and processing time increase
Solution Approach 1:
The system performs periodic monitoring of inductance, current, and conduction time parameters during induction cooker operation. The controller cyclically checks each parameter against its threshold and terminates current supply when all three parameters indicate magnetic saturation. This periodic multi-parameter monitoring achieves high detection precision while limiting the time loss through structured, rhythmic checking rather than continuous monitoring.
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 allows for a more reliable detection of magnetic saturation, preventing unsafe conditions by ensuring appropriate responses to maintain safe operation of the induction cooker.
Implementation Method 1
a varying electric current is passed through an induction coil, the coil therefore producing a corresponding varying electromagnetic field. The varying electromagnetic field induces a varying eddy current in a ferromagnetic cooking vessel or the like when the cooking vessel is placed in close proximity to the induction coil, which in turn heats the cooking vessel
Implementation Method 2
The varying electromagnetic field induces a varying eddy current in a ferromagnetic cooking vessel or the like when the cooking vessel is placed in close proximity to the induction coil, which in turn heats the cooking vessel
Implementation Method 3
measuring inductance of the induction coil and comparing the measured inductance with a predetermined threshold inductance value... determining, by comparison of the measurements with respective predetermined threshold operating values, whether the induction coil has reached magnetic saturation
Data Source
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AI summary
An induction cooker is provided having an induction coil (12) within a resonant converter circuit (12, 14), a switching arrangement comprising one or more semiconductor switches (22) linked to a current source (16, 18, 20, 21) and a switch controller (24) arranged to control the switching arrangement to supply a varying electric current at a selected frequency to the induction coil (12). The switch controller (24) is arranged selectively to receive measurements of induction coil inductance, induction coil current and semiconductor conduction time from respective measurement means and to determine, by comparison of the measurements with respective predetermined threshold operating values, whether the induction coil (12) has reached magnetic saturation and, if so, to terminate the supply of current to the induction coil (12).