Cooking Chamber Power Absorption Measurement via Impedance
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Solution Overview
Problem
Existing cooking appliances using microwave sources struggle to distinguish between power absorbed by cooking products and parasitic absorption in the cooking chamber walls or fan wheels.
Innovation Solution
A method involving feeding electromagnetic radiation into both empty and loaded cooking chambers, detecting frequency-dependent high-frequency properties, and determining cooking chamber properties to calculate the power effectively absorbed by the cooking product, while accounting for parasitic absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If microwave power is introduced into the cooking chamber, then cooking function is enabled, but parasitic absorption by chamber walls and fan wheel cannot be distinguished from product absorption
Solution Approach 1:
The total power absorption is segmented into two components: parasitic absorption (measured when chamber is empty) and product absorption (difference between loaded and empty chamber measurements). This segmentation allows precise determination of power effectively absorbed by the cooking product alone.
Solution Approach 2:
The parasitic absorption component is extracted and measured separately by performing measurements on the empty cooking chamber. This extracted parasitic value is then subtracted from the total absorption measurement to isolate the product absorption, enabling accurate power determination.
2Extent of automation
If conventional measurement methods are used, then cooking control is possible, but precise determination of effectively absorbed power is not achievable
Solution Approach 1:
The system uses feedback by continuously measuring the impedance of the cooking chamber and comparing it against reference values or expected ranges. This feedback mechanism enables real-time determination of power absorption and allows automatic adjustment of cooking parameters for precise control.
Solution Approach 2:
Traditional mechanical or thermal measurement methods are replaced with electrical impedance measurement using the microwave source. The impedance changes of the cooking chamber provide direct information about power absorption, enabling non-contact, real-time measurement without additional mechanical sensors.
3Reliability
If manual cooking state checks are performed, then cooking monitoring is possible, but time consumption and productivity are reduced
Solution Approach 1:
The cooking appliance performs self-monitoring by automatically measuring its own chamber impedance and calculating power absorption without requiring external manual checks. This self-service capability provides continuous reliable monitoring while maintaining full cooking productivity.
Solution Approach 2:
The impedance measurement and power determination occur continuously throughout the cooking process, providing uninterrupted monitoring of cooking state. This continuous action eliminates gaps in monitoring while maintaining cooking efficiency, as measurements are taken during normal operation without interrupting the cooking process.
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 precise determination of power absorbed by cooking products, allowing for improved monitoring and control of cooking processes, reducing manual checks, and optimizing cooking results.
Implementation Method 1
microwave sources are often also used in modern cooking appliances, which heat the cooking product by means of electromagnetic radiation
Implementation Method 2
incoming and outgoing waves, in particular at the feeding points of the cooking chamber, can for example be measured using the semiconductor components
Data Source
AI summary
Determining a power PGG absorbed by a cooking product present in a cooking chamber includes:S1. feeding electromagnetic radiation into an empty cooking chamber over a defined frequency range;S2. detecting a frequency-dependent high-frequency property of the empty cooking chamber over the frequency range;S3. determining a cooking chamber property Qempty of the empty cooking chamber based on the detected high-frequency property;S4. feeding electromagnetic radiation into a cooking chamber loaded with a cooking product over a defined frequency range;S5. detecting a frequency-dependent high-frequency property of the cooking chamber loaded with the cooking product over the frequency range;S6. determining a cooking chamber property Qloaded of the cooking chamber loaded with a cooking product based on the detected high-frequency property; andS7. determining a power PGG absorbed by the cooking product from the cooking chamber properties Qempty, Qloaded and a power Peff fed into the cooking chamber.