High-Frequency Power Supply Control for Reflected Wave Reduction
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Solution Overview
Problem
Existing high-frequency power supply systems experience intermodulation distortion (IMD) leading to fluctuating reflected wave power, which is difficult to reduce due to mismatched impedance and inadequate frequency modulation control, especially during pulse modulation of the second power supply's ON and OFF periods.
Innovation Solution
Implement frequency modulation and frequency offset control in the first power supply, combined with impedance matching, to minimize reflected wave power by adjusting initial phase, frequency shift, and offset frequency during both ON and OFF periods of the second power supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If frequency modulation control is performed in the second power supply OFF period, then the initial phase and frequency shift can be determined, but the power value of reflected wave power is rather increased
Solution Approach 1:
The patent applies dynamics by making the frequency control strategy adaptive to the operational state of the second power supply. The first power supply performs frequency modulation control dynamically: in the ON period, it uses frequency modulation to reduce reflected wave power; in the OFF period, it switches to frequency offset control to avoid increasing reflected wave power while still enabling determination of initial phase and frequency shift parameters.
Solution Approach 2:
The patent changes the frequency parameter of the first power supply based on the operational state. In the ON period, frequency modulation with a specific frequency shift is applied; in the OFF period, frequency offset control is used instead. This parameter change resolves the contradiction by selecting the appropriate control mode for each state.
2Reliability
If matching operation of the first matcher is performed in both ON and OFF periods, then impedance matching can be maintained, but the time required exceeds the cycle time of pulse modulation
Solution Approach 1:
The patent applies preliminary action by performing frequency control (frequency modulation in ON period, frequency offset control in OFF period) that anticipates and prepares for impedance matching conditions. This preliminary frequency control reduces the complexity and time required for subsequent matching operations, enabling them to complete within the pulse modulation cycle time.
Solution Approach 2:
The patent implements periodic action by alternating between frequency modulation control in the ON period and frequency offset control in the OFF period. This periodic switching of control modes synchronizes with the pulse modulation cycle, allowing matching operations to be performed efficiently at appropriate intervals without exceeding the cycle time.
3Loss of energy
If the first power supply performs frequency modulation control, then reflected wave power can be reduced in ON period, but the matching operation of the first matcher may have an adverse effect on determining initial phase and frequency shift
Solution Approach 1:
The patent applies segmentation by dividing the control into distinct phases: frequency modulation control is applied only in the ON period to reduce reflected wave power, while frequency offset control is applied in the OFF period to enable accurate determination of initial phase and frequency shift. This segmentation isolates the adverse effects of matching operation on parameter determination.
Solution Approach 2:
The patent applies preliminary anti-action by using frequency offset control in the OFF period to counteract the adverse effects of matching operation on parameter determination. This preliminary adjustment of frequency parameters prepares the system for accurate measurement of initial phase and frequency shift, compensating for potential interference from the matching operation.
Data Source
AI summary
A method according to the present disclosure includes: searching for an initial phase of a modulation signal at which an absolute value of a reflection coefficient or a power value of a reflected wave power at an output terminal of a first power supply calculated in a second power supply ON period is minimized in a state where a first matching operation in a first matching unit is stopped; searching for a frequency shift at which the absolute value of the reflection coefficient or the power value at the output terminal calculated in the second power supply ON period is minimized in a state where the first matching operation is stopped; and searching for an offset frequency at which the absolute value of the reflection coefficient or the power value at the output terminal calculated in a second power supply OFF period is minimized in a state where the first matching operation is stopped.