RF Power Supply Reflected Wave Control
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Solution Overview
Problem
Class-D RF generators face challenges in tolerating total reflected wave power during plasma ignition, leading to potential damage and interruption in plasma ignition operations due to high load-end power requirements and varying load impedance, which existing technologies fail to manage effectively.
Innovation Solution
A reflected wave power control method that includes a peak value dropping loop system and an arc blocking system, using detected reflected wave power to control DC voltage and prevent overload, combined with a power amount dropping loop system to manage power supply and prevent thermal damage, ensuring continuous plasma ignition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a class-D RF generator supplies RF power to a plasma load through pulse operation, then plasma ignition ability is improved, but reflected wave power increases causing thermal damage and insulation damage to the RF power amplifier device
Solution Approach 1:
The patent applies preliminary action by detecting reflected wave power before it reaches dangerous levels and controlling the RF power amplifier device in advance. The control circuit continuously monitors reflected wave power during plasma ignition and takes preventive measures by adjusting the duty ratio of the pulse control signal before thermal damage or insulation damage can occur to the RF power amplifier device.
Solution Approach 2:
The patent implements feedback control by using a control circuit that detects reflected wave power from the plasma load and feeds this information back to adjust the duty ratio of the pulse control signal. This closed-loop feedback mechanism enables real-time control of the RF power amplifier device, allowing plasma ignition while preventing reflected wave power from reaching levels that would cause thermal damage or insulation damage.
2Productivity
If forward wave power is supplied to ignite plasma, then plasma ignition is achieved, but total reflected wave power returns to the generator side causing damage to the DC power supply
Solution Approach 1:
The patent applies preliminary action by establishing a control circuit that is prepared to detect and respond to reflected wave power before total reflected wave power can damage the DC power supply. The system proactively monitors during the plasma ignition process and adjusts the duty ratio in advance to prevent the accumulation of total reflected wave power that would exceed the DC power supply's tolerance.
Solution Approach 2:
The patent implements feedback control by continuously monitoring reflected wave power and feeding this information back to the control circuit, which adjusts the duty ratio of the pulse control signal accordingly. This feedback mechanism ensures that plasma ignition operations can proceed while preventing total reflected wave power from reaching levels that would damage the DC power supply.
3Reliability
If the RF power amplifier device is protected from reflected wave power, then device reliability is improved, but plasma ignition operation must be interrupted
Solution Approach 1:
The patent applies dynamics by making the duty ratio of the pulse control signal dynamically adjustable rather than fixed. The control circuit continuously varies the duty ratio based on real-time reflected wave power detection, enabling the RF power amplifier device to be protected from reflected wave power while maintaining continuous plasma ignition operation through adaptive control.
Solution Approach 2:
The patent implements feedback control that allows continuous plasma ignition operation while protecting the RF power amplifier device. The control circuit receives continuous feedback on reflected wave power levels and dynamically adjusts the duty ratio to keep reflected wave power within safe limits, eliminating the need to interrupt plasma ignition for device protection.
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 method effectively tolerates total reflected wave power, preventing damage to RF power amplifier devices and ensuring continuous plasma ignition by dynamically controlling peak and average power levels, thereby enhancing plasma ignition performance.
Implementation Method 1
an RF generator unit (10) that converts DC of a DC power supply (11) to RFAC through a switching operation and outputs RF power
Implementation Method 2
a reflected wave power control method for use in an RF power supply, which supplies RF power to a plasma load, a feedback system that performs feedback control by feeding back a detection value of an RF output of the RF generator unit (10)
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
In an RF power supply for supplying RF power to a plasma load, reflected wave power control is performed in which the reflected wave power of an RF generator is detected and, using the detected reflected wave power, the RF generator is controlled. For a short-time variation in reflected wave power, control is performed based on a peak value variation in the detection value of reflected wave power. For a long-time variation in reflected wave power, control is performed based on a variation in a smoothed value obtained by smoothing detection values of reflected wave power. A reflected wave power control loop system includes a reflected wave power peak value dropping loop system and an arc blocking system that perform control based on a peak variation in reflected wave power and a reflected wave power amount dropping loop system that performs control based on a smoothed power amount of reflected wave power. In the non-ignition state before plasma is ignited, the RF generator provides total reflected wave power tolerance that is the ability to tolerate total reflected wave power generated when forward wave power all returns to the generator side as reflected wave power.