Dual RF Power Supply Control for Reflected Wave Reduction
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Solution Overview
Problem
Existing high-frequency power supply systems experience intermodulation distortion (IMD) that causes fluctuation in reflected wave power, particularly during the second power supply's OFF period, making it difficult to reduce reflected wave power effectively in both ON and OFF periods due to the mismatch in output states and the time required for impedance matching.
Innovation Solution
Implementing frequency modulation control in the first power supply's ON period and frequency offset control in the second power supply's OFF period, with the first power supply adjusting its output frequency to a third fundamental frequency obtained by adding an offset frequency, while maintaining consistent amplitude, to reduce reflected wave power across both periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If frequency modulation control is performed in the first power supply to reduce reflected wave power during the second power supply ON period, then the power value of reflected wave power is reduced during ON period, but the power value of reflected wave power is increased during OFF period
Solution Approach 1:
The patent applies dynamics by switching between two different control modes (frequency modulation control during ON period and frequency offset control during OFF period) based on the operational state of the second power supply. This dynamic adaptation allows the system to optimize reflected wave power reduction for each specific condition, resolving the contradiction where a single static control method cannot effectively reduce reflected wave power in both ON and OFF periods.
Solution Approach 2:
The patent changes the control parameter from frequency modulation (during ON period) to frequency offset (during OFF period). By modifying the frequency parameter differently according to the operational state, the system achieves effective reflected wave power reduction in both periods, resolving the contradiction where one parameter adjustment method cannot simultaneously optimize both states.
2Loss of energy
If impedance matching operation is performed by the first matcher, then reflected wave power can be reduced, but the time required for matching operation is longer than the pulse modulation cycle
Solution Approach 1:
The patent performs frequency offset control during the OFF period to proactively prepare the system state for the upcoming ON period. By adjusting the frequency in advance during the OFF period, the system reduces the time needed for impedance matching when the ON period begins, resolving the contradiction where matching operation time exceeds the pulse modulation cycle.
Solution Approach 2:
The patent maintains continuous frequency control across both ON and OFF periods by applying frequency modulation during ON period and frequency offset control during OFF period. This continuous adaptive control eliminates idle matching time and ensures the system is always optimized, resolving the time loss issue where matching operation would otherwise take longer than the pulse cycle.
Data Source
AI summary
A high-frequency power supply system according to the present disclosure includes a first power supply, a second power supply, a first matcher, and a second matcher. The second power supply performs pulse modulation of repeating an ON operation of outputting a second forward wave voltage and an OFF operation of not outputting the second forward wave voltage are repeated. The first power supply performs frequency modulation control in a second power supply ON period, and performs frequency offset control of outputting a forward wave voltage having a fundamental frequency obtained by adding an offset frequency to a fundamental frequency in a second power supply OFF period.