Power Converter Carrier Frequency Variation for Noise Reduction
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Solution Overview
Problem
Existing power converters using PWM control concentrate electromagnetic noise at higher harmonic components, leading to insufficient reduction of peak noise levels due to limited frequency variation during modulation periods.
Innovation Solution
A control unit for power converters that varies the carrier frequency discretely and periodically, ensuring different frequency values are used when increasing and decreasing the carrier frequency within a modulation period, thereby spreading noise energy across a wider frequency range and reducing peak noise levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the carrier frequency is varied discretely and periodically to spread electromagnetic noise, then the peak noise level is reduced, but the same frequency value may be repeated during modulation periods, limiting the effectiveness of noise spreading
Solution Approach 1:
The patent applies dynamics by making the carrier frequency variable rather than fixed. The frequency-varying unit continuously adjusts the carrier frequency according to a predetermined pattern, ensuring that the frequency changes over time and never repeats the same value within a modulation period. This dynamic frequency adjustment effectively spreads electromagnetic noise across a wider frequency spectrum, reducing peak noise levels.
Solution Approach 2:
The patent implements periodic action through the frequency-varying unit that discretely and periodically changes the carrier frequency. The frequency follows a predetermined variation pattern that repeats over modulation periods, ensuring systematic noise spreading. This periodic frequency variation maintains consistent noise distribution while preventing frequency value repetition within each modulation period.
2Object-affected harmful factors
If discrete frequency values are used for carrier wave generation, then the noise is spread over a wider frequency range, but the number of available frequency values is limited, reducing noise spreading effectiveness
Solution Approach 1:
The patent applies parameter changes by systematically varying the carrier frequency parameter according to a predetermined pattern. The frequency-varying unit changes the frequency parameter discretely through multiple distinct values, ensuring that noise energy is distributed across a broader frequency spectrum. This parameter variation approach maximizes noise spreading effectiveness while maintaining manageable system complexity.
Data Source
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AI summary
A power converter and power conversion method wherein operation of a switching element is controlled by the frequency of a carrier wave where the frequency is varied such that the same frequency of the carrier wave is not repeated during a single modulation period.