Variable Reactor Impedance Matching Using AC Flux Demagnetization
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Solution Overview
Problem
Impedance matching devices with variable reactors experience response delays due to inductance variation delays and residual magnetic flux caused by ferrite core hysteresis, affecting the speed and stability of impedance matching in RF power supply systems.
Innovation Solution
The impedance matching device employs a variable reactor with a control current that generates a magnetic field exceeding the required level to reduce inductance variation delays and uses AC magnetic fields to quickly reduce residual magnetic flux, incorporating a control current forming part and a control current generator to compute and apply AC signals for rapid impedance matching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a variable reactor with ferrite core is used for electronic impedance matching, then mechanical response delays are eliminated and maintenance is reduced, but response delays occur due to inductance variation delays and residual magnetic flux from hysteresis
Solution Approach 1:
The patent applies periodic AC magnetic fields to the ferrite core to rapidly reduce residual magnetic flux during impedance matching transitions. By superimposing AC signals on the DC control current, the system creates periodic magnetization cycles that accelerate the decay of residual flux, thereby reducing response delay while maintaining the maintenance-free electronic matching advantage
Solution Approach 2:
The patent dynamically changes the magnetic field parameters by controlling the DC current magnitude and superimposing AC signals. By adjusting the control current to exceed levels required for steady-state matching during transitions, the system accelerates inductance variation response. The AC signal frequency and amplitude are also optimized to maximize flux reduction speed
2Speed
If DC current is increased to reduce inductance variation delay, then response speed improves, but residual magnetic flux from hysteresis increases
Solution Approach 1:
The patent converts the harmful residual magnetic flux into a beneficial effect by using AC magnetic fields to accelerate its reduction. The AC signals create hysteresis loops that rapidly dissipate residual flux energy, transforming the problematic hysteresis effect into a mechanism for faster flux clearance. This allows high DC current to be applied for speed without suffering from prolonged residual flux effects
3Speed
If AC magnetic fields are applied to reduce residual magnetic flux, then impedance matching speed improves, but control system complexity increases
Solution Approach 1:
The patent merges the AC signal generation and control functions into an integrated control current forming circuit. By combining the DC current source, AC signal generator, and control logic into a unified system, the patent reduces overall complexity despite adding AC functionality. The circuit uses standard components like oscillators and modulators that can be implemented with existing electronic design techniques
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 approach significantly reduces response delays in inductance variation and impedance matching, enhancing the speed and stability of impedance matching in RF power supply systems, particularly in applications like semiconductor production and plasma processing.
Implementation Method 1
The control winding 102a is wound around a central part of the ferrite core 102c, and DC current passes therethrough
Implementation Method 2
The ferrite core used in the variable reactor has nonlinear hysteresis property, and the magnetic permeability μ is represented by a gradient on the B-H curve
Implementation Method 3
magnetic fields generated by the main winding 102b1 and the main winding 102b2 are canceled each other at the central part of the ferrite core 102c
Data Source
Figure 1
Figure 2A~2C
Figure 3A~3B
AI summary
An impedance matching device comprising a variable reactor having a main winding and control winding, wherein a generated magnet field in the core is an AC magnetic field with a magnitude exceeding a value to settle a deviation between a control target value for impedance matching and a feedback value, by changing the magnitude of the generated magnetic field by changing a control current passing through the control winding, thereby controlling inductance of the variable rector to be a predetermined value to perform impedance matching, the response delay in the impedance matching is reduced by reducing a response delay in the inductance variation of the variable reactor.