Induction Cooktop Coil Detection Using Multi-Frequency Resonant Current
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Solution Overview
Problem
Conventional cooking apparatuses cannot accurately determine whether an object to be heated is a specific cooking tool optimized for the apparatus, leading to difficulties in controlling heating output and ensuring proper food cooking according to user intentions.
Innovation Solution
A cooking apparatus with a working coil, inverter, current detector, and controller that outputs resonant currents at different frequencies to determine if an adjacent object is a predetermined object, allowing for precise identification of the object's material and control of heating based on its magnetic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the cooking apparatus uses conventional single-frequency resonant current detection, then the device complexity is low, but the measurement precision for determining object material and cooking tool type is insufficient
Solution Approach 1:
The patent applies periodic action by sequentially outputting resonant currents at multiple different frequencies to the working coil and measuring the current magnitude at each frequency. This periodic multi-frequency detection enables the controller to determine both the material type (magnetic/non-magnetic) and specific cooking tool type by analyzing the pattern of current magnitudes across different frequencies, thereby improving measurement precision without requiring complex simultaneous multi-frequency measurement hardware
Solution Approach 2:
The patent changes the frequency parameter of the resonant current output by the inverter to achieve material determination. By varying the frequency parameter and observing how the current magnitude responds at different frequencies, the system can distinguish between different material types and cooking tool types. This parameter change approach allows accurate material determination using the existing working coil and inverter without adding complex new components
2Adaptability or versatility
If the cooking apparatus determines only magnetic or non-magnetic material, then the device complexity is low, but the adaptability for optimizing heating control for specific cooking tools is insufficient
Solution Approach 1:
The controller performs periodic detection at multiple frequencies and analyzes the pattern of current magnitudes to determine not only whether the object is magnetic or non-magnetic but also to identify specific cooking tool types. This periodic multi-frequency measurement enables the system to adapt heating control parameters according to the specific cooking tool type, improving versatility while using the existing detection infrastructure
Solution Approach 2:
The existing working coil and inverter are made multi-functional by using them for both normal induction heating operations and for material/cooking tool type detection. By controlling the inverter to output resonant currents at different frequencies during detection mode, the same hardware components serve dual purposes: heating when needed and characterization when detection is required. This universality improves adaptability without proportionally increasing device complexity
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
Enables accurate determination of the object's material and specific cooking tool, preventing safety issues and ensuring optimal heating performance, thus improving user satisfaction and reliability by providing appropriate heating outputs.
Implementation Method 1
The induction type electric range generates a strong magnetic field line by passing a high-frequency current through a working coil provided therein. For example, when the magnetic field line, which are generated by the working coil passes through a cooking tool such as a metal pot, an eddy current is formed in the cooking tool.
Implementation Method 2
when the magnetic field line, which are generated by the working coil passes through a cooking tool such as a metal pot, an eddy current is formed in the cooking tool. In addition, as the eddy current flows through the cooking tool, heat is generated so that the cooking tool itself is heated
Implementation Method 3
as the eddy current flows through the cooking tool, heat is generated so that the cooking tool itself is heated
Data Source
AI summary
A cooking apparatus includes: a working coil, an inverter configured to output a resonant current to the working coil, a current detector configured to detect the resonant current and output a detection value corresponding to the resonant current, and a controller. The controller is configured to control the inverter to flow a first resonant current through the working coil, control the inverter to flow, through the working coil, a second resonant current having a frequency different from the first resonant current, and determine, based on a difference between a first detection value for the first resonant current and a second detection value for the second resonant current, whether a target object that is located adjacent to the working coil is a predetermined object.