Hob Sensor Unit Phase Shift Detection for Interference Reduction
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Solution Overview
Problem
Existing induction hobs face detection errors due to electromagnetic interactions between heating coils and separate sensor circuits, limiting reliable continuous detection of cookware, especially when multiple coils operate with phase-offset mains AC voltages.
Innovation Solution
A hob apparatus with a separate sensor unit and control unit that determines state variables based on phase shifts and amplitude ratios between sensor signals, minimizing electromagnetic interference and enabling accurate detection of cookware presence and coverage, using a signal amplification unit and high-resolution sensors for continuous operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a separate sensor circuit is used to detect cookware, then detection accuracy is improved, but electromagnetic interactions with heating coils cause detection errors
Solution Approach 1:
The system divides the detection function into multiple independent sensor circuits, each assigned to specific heating coil groups. This segmentation allows the control unit to selectively activate only the sensor circuits needed for current operation, isolating them from electromagnetic interference generated by non-operating coils.
Solution Approach 2:
The sensor circuits are activated periodically in synchronization with the operation cycles of heating coils. By timing the sensor activation to coincide with periods when heating coils are not generating strong electromagnetic fields, the system minimizes interference while maintaining continuous monitoring capability.
2Adaptability or versatility
If multiple heating coils operate with phase-offset mains AC voltages, then simultaneous operation of several heating units is enabled, but amplified electromagnetic interactions increase detection errors
Solution Approach 1:
The system assigns specific sensor circuits to specific heating coil groups, creating independent detection zones. This segmentation allows the control unit to activate only the sensor circuits corresponding to actively heated zones, isolating them from electromagnetic interference generated by other coils operating with phase-offset voltages.
Solution Approach 2:
The control unit acts as an intermediary that coordinates between multiple heating coils and sensor circuits. It manages the phase-offset operations of multiple coils while selectively activating appropriate sensor circuits, mediating the interaction to prevent amplified electromagnetic interference from causing detection errors.
3Object-affected harmful factors
If detection is performed only during zero passage of mains AC voltage, then electromagnetic interactions are reduced, but continuous detection is prevented
Solution Approach 1:
Sensor circuits are activated periodically in synchronization with the AC voltage cycles and heating coil operation phases. By timing sensor activation to occur during periods of reduced electromagnetic interference while maintaining continuous monitoring through coordinated periodic operation, the system achieves both interference reduction and detection continuity.
Solution Approach 2:
The system maintains continuous cookware detection capability by coordinating multiple sensor circuits to operate continuously across different time phases. While individual sensors operate periodically to avoid interference, the collective system provides uninterrupted monitoring, ensuring continuous useful detection action.
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 solution provides reliable, accurate, and continuous detection of cookware, reducing errors and enhancing user convenience by separating the sensor unit from the heating unit and using advanced signal processing techniques.
Implementation Method 1
it is concluded that cookware is present above the heating unit based on a change in an electrical parameter of the circuit, for example a change in inductance
Implementation Method 2
The electromagnetic fields generated by the heating coils during operation can result in unwanted interactions with the sensor circuit
Implementation Method 3
the control unit determines at least one state variable relating to the heating unit based on a phase shift and/or an amplitude ratio between the sensor signal and a further signal
Data Source
AI summary
A hob apparatus includes a heating unit, a sensor unit separate from the heating unit and configured to include an electric resonant circuit and to detect a sensor signal, and a control unit configured to control the sensor unit and to analyze the sensor signal. The control unit determines in an operating state a state variable relating to the heating unit based on a phase shift and/or an amplitude ratio between the sensor signal and a further signal.