RF Power Burst Control to Suppress Amplifier Temperature Overshoot
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Solution Overview
Problem
Conventional RF energy radiation devices experience overshoot in RF power output during burst operations due to temperature changes in the power amplifier, affecting the accuracy of output control and the quality of microwave heating.
Innovation Solution
The RF energy radiation device employs a controller that switches the output control from closed-loop to open-loop during specified conditions, such as temperature changes or stopping periods, to suppress overshoot and improve accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If closed-loop control is used to control RF power output, then output control accuracy is improved, but temperature changes in power amplifier cause overshoot phenomenon
Solution Approach 1:
The control method dynamically switches between closed-loop control and open-loop control based on the operating state. During burst operation when temperature changes rapidly, the system switches to open-loop control to avoid overshoot. During continuous operation with stable temperature, the system uses closed-loop control for accurate output control. This dynamic switching resolves the contradiction between control accuracy and stability.
Solution Approach 2:
The invention changes the control parameter (control mode) based on temperature conditions. When temperature changes exceed a threshold or during burst operation, the system switches from closed-loop to open-loop control. This parameter change allows the system to adapt to different thermal states, preventing overshoot while maintaining control accuracy when appropriate.
2Productivity
If burst operation is performed with short cycles, then heating efficiency is improved, but temperature characteristics of power amplifier affect output RF power quality
Solution Approach 1:
The system performs preliminary detection of temperature conditions before executing burst operation. When temperature changes are detected or during the stopping period of burst operation, the control mode is switched to open-loop in advance. This preliminary action prevents overshoot from occurring, ensuring output RF power quality while maintaining high heating efficiency through burst operation.
3Stability of the object's composition
If open-loop control is used during burst operation, then overshoot phenomenon is suppressed, but output control accuracy deteriorates
Solution Approach 1:
The system dynamically adjusts control mode based on operational phase. During burst operation's stopping period when temperature instability causes overshoot, open-loop control is used for stability. During continuous operation when temperature is stable, closed-loop control is switched back for accurate output control. This dynamic adjustment resolves the contradiction between stability and accuracy.
Solution Approach 2:
The control mode is periodically switched according to the burst operation cycle. Open-loop control is applied during the stopping period to prevent overshoot, then closed-loop control is restored during the output period for accurate control. This periodic switching pattern allows the system to maintain both stability during temperature transitions and accuracy during stable operation.
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 effectively suppresses the overshoot of RF power, enhancing the accuracy of output control and improving the quality of microwave heating in RF energy radiation devices.
Implementation Method 1
the power amplifier amplifies the radio frequency signal to output radio frequency power (RF power)
Implementation Method 2
the radiation element radiates the radio frequency power
Implementation Method 3
the detector detects the radio frequency power travelling toward the radiation element as progressive wave power
Implementation Method 4
The RF power is fed to cavity 207 to heat object 208, which is placed in cavity 207 to be heated, by the microwave energy
Data Source
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AI summary
An RF energy radiation device of this disclosure comprises: an oscillator; a power amplifier; a radiation element; a detector; and a controller. The oscillator generates an RF signal. The power amplifier amplifies the RF signal to output RF power. The radiation element radiates the RF power. The detector detects progressive wave power. The controller performs an RF power output control using a closed-loop control for setting an output set value of the RF power by a closed-loop and an open-loop control for setting the output set value of the RF power by an open-loop. In a burst operation alternately switching between a period of outputting the RF power and a period of stopping the RF power, the controller changes the RF power output control from the closed-loop control to the open-loop control when a specified condition for change is satisfied during the period of stopping the RF power.