RF Defrosting Apparatus with Impedance-Based Mass Estimation
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Solution Overview
Problem
Conventional capacitive food defrosting systems face inefficiencies due to changes in load impedance during defrosting, leading to inaccurate determination of defrosting completion and potential over or under-heating, and require physical weight sensors, which increase complexity and cost.
Innovation Solution
A thermal increase system that estimates the mass of the load using a look-up table and variable impedance matching networks to adjust RF signal parameters, allowing for efficient and even defrosting without the need for physical weight sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If physical weight sensors are used to determine load weight, then measurement precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent replaces physical weight sensors (mechanical system) with an electrical measurement system that uses RF power measurements and impedance analysis to determine load mass. The controller measures the real power delivered to the load and uses this electrical data to estimate mass, eliminating the need for mechanical sensors and reducing system complexity.
Solution Approach 2:
The patent introduces an intermediary measurement approach by using RF power consumption as a mediator to infer load mass. Instead of directly measuring weight, the system measures the electrical power consumed by the load during defrosting, which correlates with mass, and uses this intermediate measurement to control the defrosting process.
2Device complexity
If user input is used for load weight characterization, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the controller continuously measures the real power delivered to the load during defrosting and uses this feedback to monitor and adjust the defrosting process. By measuring power consumption over time and comparing it against expected power-mass relationships, the system automatically determines load mass with high precision without requiring user input.
Solution Approach 2:
The system performs self-measurement of load mass by automatically measuring its own power consumption during operation. The controller independently determines the load mass through electrical measurements without external intervention, making the system self-sufficient and eliminating the need for user input while maintaining high precision.
3Device complexity
If defrosting duration is determined by timer, then device complexity is reduced, but manufacturing precision deteriorates
Solution Approach 1:
The patent replaces open-loop timer control with closed-loop feedback control by continuously measuring the real power delivered to the load and using this information to determine defrosting completion. The controller monitors power consumption patterns and impedance changes to detect when defrosting is complete, ensuring precise termination regardless of load mass variations.
Solution Approach 2:
The patent dynamically adjusts defrosting control parameters based on measured power consumption and impedance changes. Instead of using a fixed timer duration, the system modifies the defrosting process parameters in real-time based on actual load conditions, achieving precise defrosting completion detection adapted to different load masses and types.
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
The system ensures precise control of the defrosting process, achieving efficient and uniform heating by dynamically adjusting RF signal parameters based on estimated load mass, thereby improving defrosting accuracy and reducing costs.
Implementation Method 1
supplying, by a radio frequency (RF) signal source, one or more RF signals to a transmission path that is electrically coupled between the RF signal source and one or more electrodes that are positioned proximate to a cavity
Implementation Method 2
modifying, by a controller, one or more component values of an impedance matching network that is electrically coupled along the transmission path
Data Source
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AI summary
A defrosting system includes an RF signal source, one or more electrodes proximate to a cavity within which a load to be defrosted is positioned, a transmission path between the RF signal source and the electrode(s), and an impedance matching network electrically coupled along the transmission path between the RF signal source output and the electrode(s). A system controller is configured to modify, based on the reflected signal power, values of variable passive components of the impedance matching network to reduce the reflected signal power. The system controller may be configured to estimate the mass of the load by comparing component value(s) of one or more variable passive components of the impedance matching network with a component value table stored in memory, where stored mass values correspond to the stored component values. Desired signal parameters for the RF signal may be determined based on the estimated mass of the load.