Cooking Vessel Detection Timing to Reduce Heating Coil Interference
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Solution Overview
Problem
Existing cooking appliances face challenges in accurately detecting a cooking vessel on a cooking plate due to interference from induced electromotive forces generated by the heating coil, which affects the vessel detection circuit's accuracy.
Innovation Solution
The cooking appliance incorporates a vessel detection circuit with a vessel detection coil and a heating coil, where a controller controls switches to allow input and output currents through the detection coil at specific times relative to the heating coil's driving frequency, using an A/D converter and multiplexer to convert signals, and includes a Zener diode circuit to manage voltage, thereby minimizing interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a vessel detection circuit is used to detect cooking vessels on a cooking plate, then vessel detection capability is improved, but the detection accuracy deteriorates due to interference from induced electromotive forces generated by the heating coil
Solution Approach 1:
The patent applies periodic action by controlling the switch to allow current flow through the vessel detection coil only during specific time intervals that are synchronized with the driving frequency of the heating coil. This periodic switching enables the detection circuit to operate during windows when the induced electromotive force from the heating coil is minimized or zero, thereby maintaining detection capability while improving detection accuracy by avoiding interference peaks
Solution Approach 2:
The patent implements preliminary action by pre-synchronizing the switch control with the driving frequency of the heating coil. The controller is configured to anticipate the cycles of the heating coil and open the switch during periods when induced electromotive force would be maximum, thereby preventing interference before it can affect detection accuracy
2Power
If the heating coil generates a magnetic field for cooking, then heating function is improved, but interference to the vessel detection circuit increases
Solution Approach 1:
The patent applies the taking out principle by separating the operation of the heating coil and vessel detection circuit in time. The switch isolates the vessel detection coil from the circuit during periods when the heating coil is actively generating strong magnetic fields, effectively extracting or removing the detection function from the interfering electromagnetic environment while maintaining full heating power
Solution Approach 2:
The patent implements preliminary anti-action by using the controller to preemptively open the switch and disconnect the vessel detection coil from the circuit before the heating coil generates harmful levels of induced electromotive force. This preventive measure counteracts the harmful interference before it can affect the detection circuit, allowing the heating coil to operate at full power without compromising detection integrity
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 enables accurate detection of the cooking vessel without interference from the heating coil's magnetic field or induced electromotive force, allowing for precise positioning and type identification while maximizing the number of vessel detection coils and heating coils.
Implementation Method 1
a vessel detection coil, and at least one switch controllable to allow a flow of an input current into the vessel detection coil and a flow of an output current from the vessel detection coil
Implementation Method 2
a heating coil below the cooking plate and configured to generate a magnetic field that extends through the cooking plate and the vessel detection circuit based on a driving power having a driving frequency being applied to the heating coil
Data Source
AI summary
A cooking appliance may include: a cooking plate (CP); a vessel detection (VD) circuit including: a VD coil, and at least one switch that is controllable to allow current into, and from, the VD coil, wherein the VD circuit is configured to, while the at least one switch is controlled to allow current into, and from, the VD coil, detect a position or type of cooking vessel on the CP; a heating coil below the CP configured to generate a magnetic field extending through the CP and VD circuit based on a power having a frequency being applied to the heating coil; and a controller configured to control the at least one switch so that, for a time at each period of a plurality of periods corresponding to the frequency, while the power is applied to the heating coil, current into, and from, the VD coil are allowed.