Induction Cooking Phase Correction for Accurate Pan Detection
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Solution Overview
Problem
Induction cook-tops heat conductive cookware unintentionally due to invisible magnetic fields, risking damage to items placed on the cook-top without apparent power indication.
Innovation Solution
A method and system for determining phase difference between induction coil current and voltage across a resonant tank using a phase error approximation model to correct measured phase values, improving precision and safety by adjusting power delivery based on pan characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase measurement is performed without correction, then device complexity is reduced, but measurement precision deteriorates due to phase errors in the induction cooking appliance
Solution Approach 1:
The patent replaces complex analog phase correction circuitry with digital signal processing techniques. The controller digitally measures phase differences between current and voltage signals, applies correction based on pre-stored approximation models, and outputs corrected phase values. This substitution of mechanical/analog systems with electronic/digital systems achieves high measurement precision while keeping the physical device structure relatively simple.
Solution Approach 2:
The patent introduces a phase error approximation model as an intermediary between the raw phase measurement and the final corrected phase value. This model, stored in the controller, acts as a mediator that translates measured phase differences into accurate power factor corrections without requiring complex real-time calculations, thus resolving the contradiction between precision and complexity.
2Reliability
If power delivery is adjusted based on pan characteristics, then reliability improves by preventing unintentional heating, but device complexity increases due to additional sensing and control requirements
Solution Approach 1:
The patent implements a feedback mechanism where the controller continuously monitors the phase difference between current and voltage, determines pan presence and characteristics based on this feedback, and adjusts power delivery accordingly. The system compares measured phase values against predetermined thresholds to detect pan presence and modifies operating parameters in real-time, creating a closed-loop control system that enhances safety while managing complexity through intelligent feedback processing.
Solution Approach 2:
The patent changes operating parameters (power delivery, switching frequency) based on detected pan characteristics. The controller adjusts these parameters dynamically according to the phase measurements and pan detection results, allowing the system to adapt to different cooking scenarios and prevent unintentional heating of non-cooking items while optimizing cooking performance.
3Measurement precision
If phase error approximation model is used, then measurement precision improves, but manufacturing precision requirements increase for the control system
Solution Approach 1:
The patent performs preliminary action by pre-storing phase error approximation models in the controller before actual operation. These models are created offline through characterization of the specific induction cooking appliance, capturing the unique phase error characteristics. During operation, the controller simply retrieves and applies the pre-computed model, avoiding the need for high-precision real-time manufacturing of correction parameters while still achieving accurate phase error compensation.
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
Enhances precision in power estimation and pan detection, reducing unintentional heating and improving safety by accurately determining phase errors and pan presence.
Implementation Method 1
An induction cook-top applies radio frequency current to a heating coil to generate a strong radio frequency magnetic field on the heating coil. When a conductive vessel, such as a pan, is placed over the heating coil, the magnetic field coupling from the heating coil generates eddy currents on the vessel, causing the vessel to increase in temperature.
Implementation Method 2
the magnetic field coupling from the heating coil generates eddy currents on the vessel, causing the vessel to increase in temperature
Data Source
AI summary
A method for determining a phase in an induction cooking appliance is provided. The method may include determining a measured phase value indicative of a phase difference between an induction coil current and a voltage across a resonant tank of the induction cooking appliance. The method may further include obtaining a phase error of the measured phase value using a phase error approximation model. The method may further include adjusting the measured phase value based, at least in part, on the phase error approximation model to determine an output signal indicative of the induction cooking appliance.