Impedance Matching Device Frequency Control
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Solution Overview
Problem
Conventional high-frequency power systems fail to promptly address impedance mismatches in loads, such as plasma treatment devices, which can lead to unstable plasma or misfire due to continuously changing load impedance.
Innovation Solution
An impedance matching device that adjusts the oscillation frequency of the high-frequency power source using a first slope to improve the matching condition and then shifts back to the original frequency with a more gradual second slope, ensuring rapid mismatch correction and preventing hunting oscillations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the oscillation frequency is changed rapidly to improve impedance matching, then the matching speed is improved, but hunting oscillations occur causing instability
Solution Approach 1:
The patent implements a periodic two-stage frequency adjustment cycle: a first frequency adjustment period with a first slope for rapid matching improvement, followed by a second frequency adjustment period with a second (smaller) slope for stabilization. This periodic action allows the system to quickly correct impedance mismatches while preventing hunting oscillations through the stabilizing second phase.
Solution Approach 2:
The patent dynamically changes the frequency adjustment slope based on the operational phase. During the first frequency adjustment period, a larger first slope is applied for rapid response. During the second frequency adjustment period, a smaller second slope is applied to dampen oscillations and stabilize the matching condition, creating a dynamic adaptation to system state.
2Adaptability or versatility
If the matching circuit constants are mechanically changed to achieve wide matching range, then the matching range is improved, but the matching speed becomes slow
Solution Approach 1:
The patent replaces mechanical constant changes in the matching circuit with electronic frequency control of the power source. By substituting the mechanical adjustment mechanism with electronic frequency modulation, the system achieves both wide matching range (through frequency variation) and fast response speed (through electronic control), eliminating the speed limitation of mechanical systems.
Solution Approach 2:
The patent changes the operating frequency parameter of the high-frequency power source to achieve impedance matching. By varying the frequency parameter electronically rather than mechanically adjusting circuit constants, the system achieves rapid adaptation across a wide matching range, resolving the contradiction between matching range and matching speed.
3Measurement precision
If the oscillation frequency is continuously adjusted to track changing load impedance, then the matching accuracy is improved, but hunting oscillations occur causing plasma instability
Solution Approach 1:
The patent uses periodic frequency adjustment with alternating slopes to achieve accurate tracking of changing load impedance while preventing hunting oscillations. The first slope provides rapid response to impedance changes for accurate matching, while the second slope provides damping to maintain plasma stability, creating a stable periodic control cycle.
Solution Approach 2:
The patent implements feedback control by continuously monitoring the impedance matching condition and adjusting the frequency accordingly. The control portion receives information about the matching condition and automatically adjusts the oscillation frequency with appropriate slopes to maintain optimal matching while preventing instability, creating a closed-loop feedback system.
Data Source
AI summary
Provided is an impedance matching device capable of promptly improving an impedance mismatch between a high-frequency power source and a load even when the impedance of the load continuously changes.An impedance matching device according to the present invention is for use in a high-frequency power system configured to supply a load with an output from a high-frequency power source via a matching circuit whose constant is mechanically changed, and the impedance matching device includes a matching condition value acquisition portion for acquiring a matching condition value indicating a matching condition between the high-frequency power source and a load, and a control portion for controlling an oscillation frequency of the high-frequency power source based on the matching condition value. When the matching condition value indicates deterioration of the matching condition, the control portion changes the oscillation frequency with a first slope toward improving the matching condition, and thereafter shifts the oscillation frequency back to an original value with a second slope more gradual than the first slope.