High-Frequency Power Supply Synchronization for IMD Reflected Wave Reduction
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Solution Overview
Problem
High-frequency power supply apparatuses face challenges in minimizing InterModulation Distortion (IMD) induced reflected wave power, especially when simultaneously inputting high-frequency voltages with different frequencies to plasma generation apparatuses, as the impedance automatic matching function struggles to keep pace with rapid variations in reflected wave power.
Innovation Solution
The high-frequency power supply apparatus includes a first power supply, a second power supply, matching circuits, a detection circuit, a period signal generation circuit, and a waveform control circuit. It generates a period signal synchronized with IMD by detecting the first voltage, and uses this signal to perform frequency modulation on the first voltage, thereby reducing reflected wave power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If impedance automatic matching function is used for each high-frequency power, then power supply stability is improved, but reflected wave power reduction is insufficient due to fast variation caused by IMD
Solution Approach 1:
The patent introduces a feedback mechanism where the first voltage is detected, squared to generate a period signal matching the second voltage's frequency and phase, and this period signal is used to modulate the first voltage. This closed-loop feedback enables dynamic compensation for IMD-induced reflected wave power variations that the conventional open-loop impedance matching cannot address.
Solution Approach 2:
The patent dynamically changes the frequency parameter of the first voltage by applying frequency modulation using the period signal. This parameter change allows the first voltage to adapt to the varying impedance conditions caused by IMD, thereby reducing reflected wave power while maintaining power supply stability.
2Loss of energy
If frequency modulation is performed using a signal synchronized with the second voltage, then reflected wave power is reduced, but system complexity increases due to different system clocks
Solution Approach 1:
The patent introduces an intermediary processing stage where the detected first voltage is squared to generate a period signal. This intermediary signal serves as a mediator that bridges the two different system clocks, enabling synchronization without requiring direct clock transmission or complex timing coordination between the first and second power supplies.
Solution Approach 2:
The patent creates a copy of the timing information by squaring the detected first voltage to generate a period signal that replicates the frequency and phase characteristics of the second voltage. This copying approach eliminates the need for direct signal transmission between power supplies, simplifying the system configuration while achieving synchronized frequency modulation.
3Measurement precision
If cable transmission is used to transmit timing signal from second power supply to first power supply, then frequency modulation synchronization is achieved, but configuration becomes complicated and cost increases
Solution Approach 1:
The patent implements a self-service mechanism where the first power supply generates its own synchronization signal by processing its detected voltage output. The detected first voltage is squared to create a period signal that inherently contains the timing information needed for frequency modulation, eliminating the need for external timing signal transmission and reducing system complexity.
Solution Approach 2:
The patent replaces the mechanical/electrical signal transmission system (cable-based timing signal transmission) with a signal processing system. By squaring the detected voltage to generate the period signal, the patent substitutes physical signal transmission with mathematical transformation, achieving the same synchronization function with reduced complexity and cost.
Data Source
AI summary
A high-frequency power supply apparatus includes the following elements. A first power supply supplies first power to a load by outputting a first voltage whose fundamental frequency is higher than a second voltage output by a second power supply. A period signal generation circuit generates a period signal matching a frequency and a phase of the second voltage. A waveform control circuit generates a modulation signal for performing frequency modulation on a fundamental wave signal of the first voltage, and adjusts an output timing of the modulation signal in accordance with a timing of the period signal. The first power supply generates a first frequency signal by performing frequency modulation on the fundamental wave signal of the first voltage by using the modulation signal. The first power supply performs power amplification on the first frequency signal and outputs, to the load, the first frequency signal as first power.