Heating Cable Arrangement for RF Power and Control Merging
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Solution Overview
Problem
Conventional heating appliances using microwave ovens face inefficiencies due to the use of magnetrons, which are bulky, prone to performance degradation, and operate at high frequencies that do not allow deep energy penetration into loads, leading to uneven and slow heating.
Innovation Solution
The development of a heating appliance that utilizes a solid-state RF signal source generating low-frequency RF energy (1 MHz-300 MHz) for capacitive heating systems, combined with optional thermal heating, featuring a single-ended or double-ended variable impedance matching network dynamically controlled to optimize RF power delivery and reduce heating time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If magnetrons are used in conventional microwave heating systems, then high-frequency RF energy can be generated, but the energy penetration depth into the load is limited and heating becomes uneven and slow
Solution Approach 1:
The patent changes the operating frequency parameter from conventional high-frequency microwave (2.45 GHz) to low-frequency RF (1-300 MHz). This parameter change increases the wavelength and penetration depth of the electromagnetic energy, allowing deeper and more uniform heating of the load while maintaining efficient energy transfer through impedance matching networks
2Reliability
If separate electrical cables are used to communicate RF energy and control signals between PAM and STU, then reliable signal transmission is achieved, but device complexity and connection requirements increase
Solution Approach 1:
The patent merges the transmission of RF energy and control signals into a single electrical cable connection between the PAM and STU. This is achieved by modulating control signals onto the RF energy carrier wave, allowing both power and control information to be transmitted through the same physical medium, thereby reducing connection complexity while maintaining reliable communication
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 solution enables faster, more even, and efficient heating by allowing deeper energy penetration and dynamic impedance matching, reducing heating time and improving energy absorption within the load.
Implementation Method 1
Capacitive heating systems include planar electrodes contained within a heating compartment. After a load (e.g., a food load) is placed between the electrodes, electromagnetic energy is supplied to the electrodes to provide warming or cooking of the load.
Implementation Method 2
The STU includes an impedance matching circuit that is configured to provide efficient delivery of the RF energy to the appliance's heating cavity.
Data Source
AI summary
A system includes an RF signal source configured to output an RF signal at a first frequency, and a first controller configured to generate a first data signal encoding instructions at a second frequency. A first filter is coupled to the RF signal source. The first filter is a low pass filter having a cutoff frequency between the first frequency and the second frequency. The first filter is configured to couple to a first end of a cable. A second filter is coupled to the first controller. The second filter is a high pass filter having a cutoff frequency between the first frequency and the second frequency. The second filter is configured to couple to the first end of the cable. The system includes an impedance matching network configured to couple to a second end of the cable. A first electrode is coupled to the impedance matching network.