Induction Cooktop Phase-Angle Detection for Small Pans
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Solution Overview
Problem
Conventional induction cooktops fail to detect small pans accurately, leading to the cooktop control system not activating the inductors, which prevents heating of these pans.
Innovation Solution
A controller system that selectively activates inductors based on user input and detects pan presence using a phase angle between the zero-crossing of an induced current and the leading edge of a voltage across an inverter switch, allowing for identification of small pan conditions and improved detection and operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional current monitoring is used for pan detection, then large pans are detected accurately, but small pans are not detected leading to failure to activate inductors
Solution Approach 1:
The patent changes the detection parameter from simple current monitoring to phase angle measurement. By measuring the phase angle between the voltage across the inductor and the current through it, the system can detect the presence of small pans that were previously undetectable by conventional current monitoring methods
Solution Approach 2:
The patent replaces the conventional current-based detection mechanism with a phase angle-based detection mechanism. This substitution allows the system to detect small pans by measuring the phase shift in the electrical parameters, which occurs when a pan is present on the cooktop
2Extent of automation
If automatic pan detection is implemented, then pan presence is monitored, but small pans cause false negatives resulting in no heating
Solution Approach 1:
The patent implements a feedback mechanism where the controller continuously monitors the phase angle of the inductor current and adjusts the inductor activation accordingly. When a small pan is detected through phase angle measurement, the system provides feedback to activate the inductor, ensuring reliable heating for pans of all sizes
Solution Approach 2:
The system performs preliminary detection using phase angle measurement before activating the heating process. This preliminary action allows the controller to identify small pans that would otherwise be missed, ensuring that the inductor is activated in advance for reliable heating
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 the cooktop to accurately detect and heat small pans, enhancing the versatility and functionality of the induction cooking system by preventing false detection and ensuring power transfer to smaller pans.
Implementation Method 1
inductors comprising coils of copper wire where an oscillating current (e.g. an alternating current) is circulated producing an oscillating electromagnetic field. The electromagnetic field has the main effect of inducing a parasitic current inside the pan
Implementation Method 2
The parasitic current circulating in the pan produces heat by dissipation
Data Source
AI summary
An induction cooktop includes a ceramic cooking surface in connection with a housing. A plurality of inductors is disposed in the housing and each of the inductors is in communication with a controller. The controller is configured to selectively activate each of the inductors in response to an input received at the user interface identifying an active inductor of the plurality of inductors to activate. The controller is further configured to detect a presence of a pan proximate the active inductor in response to a detection signal and identify a small pan condition in response to a phase angle detected for the active inductor of the plurality of inductors.