High-Frequency Power Supply Modulation for IMD and Reflected Power
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Solution Overview
Problem
High-frequency power supply apparatuses experience intermodulation distortion (IMD) when a sinusoidal high-frequency voltage is combined with a rectangular negative-polarity voltage, making it difficult to reduce reflected wave power despite frequency modulation control.
Innovation Solution
Implementing a first power supply that performs frequency modulation on a high-frequency voltage using a trapezoidal modulation signal equal to a second fundamental frequency, combined with a matching circuit and low-pass filter to match impedance and reduce IMD.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If frequency modulation control is performed using a rectangular modulation signal corresponding to the negative polarity voltage, then the control structure is simple, but the reflected wave power caused by IMD cannot be reduced
Solution Approach 1:
The patent changes the waveform parameter of the modulation signal from rectangular to trapezoidal. This parameter change allows the signal to better match the actual negative polarity voltage waveform, enabling effective reduction of reflected wave power caused by IMD while maintaining control simplicity.
Solution Approach 2:
The patent introduces dynamic adaptation by making the modulation signal waveform follow the actual voltage waveform characteristics. The trapezoidal signal dynamically adjusts to match the negative polarity voltage transitions, enabling the system to adapt to waveform variations and effectively suppress IMD-related reflections.
2Ease of operation
If a sinusoidal high-frequency voltage is combined with a rectangular negative-polarity voltage, then the power supply operation is straightforward, but intermodulation distortion occurs
Solution Approach 1:
The patent changes the modulation signal waveform parameter from rectangular to trapezoidal to match the actual negative polarity voltage. This parameter alignment eliminates the waveform mismatch that causes IMD, allowing straightforward operation while preventing distortion.
Solution Approach 2:
The patent converts the potentially harmful rectangular waveform mismatch into a beneficial trapezoidal waveform that matches the actual voltage characteristics. By aligning the modulation signal with the actual voltage waveform, the system transforms what would be a source of distortion into an effective control mechanism.
Data Source
AI summary
A high-frequency power supply apparatus includes a first power supply, a second power supply, a matching circuit, and a low-pass filter. The first power supply outputs a high-frequency voltage with a first fundamental frequency toward a load. The second power supply outputs, toward the load, a negative polarity voltage with a second fundamental frequency lower than the first fundamental frequency. The matching circuit is connected between the first power supply and the load. The matching circuit matches impedance on a side of the first power supply and impedance on a side of the load. The low-pass filter is connected between the second power supply and the load. The first power supply performs frequency modulation control by: performing frequency-modulation on the high-frequency voltage with a trapezoidal modulation signal whose frequency is equal to the second fundamental frequency, and outputting a modulated wave obtained by the frequency-modulation on the high-frequency voltage.