Power Converter Noise Suppression via Phase-Shifted Cells
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Solution Overview
Problem
Conventional power converters used for power distribution are bulky due to multiple transformers, leading to increased weight and volume, and generate noise through output current harmonics that can cause vibrations in reactors, particularly in residential areas.
Innovation Solution
A power converter design featuring cascade-connected converter cells with phase-shifted carrier waves and operating frequencies above the human audible range, suppressing noise by ensuring output current harmonic frequencies exceed the maximum human audible frequency, thereby reducing noise propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple transformers are used to increase output voltage, then high voltage output is achieved, but weight and volume of the apparatus increase
Solution Approach 1:
The power converter is divided into multiple converter cells (first, second, third, and fourth converter cells) connected in cascade, each contributing to the overall output voltage. This segmentation allows high voltage output without requiring large transformers, as each cell operates at a lower voltage level individually while achieving high voltage collectively through series connection.
Solution Approach 2:
The patent replaces the mechanical transformer-based voltage transformation system with an electronic cascade converter cell system. Instead of using electromagnetic transformers to step up voltage, the invention uses controlled switching of converter cells with phase-shifted carrier waves to synthesize high voltage output electronically, eliminating the need for bulky transformers.
2Manufacturing precision
If converter cells operate at high switching frequencies, then output voltage quality improves, but noise generation increases due to reactor vibrations
Solution Approach 1:
The patent introduces asymmetric phase shifting between carrier waves of different converter cells, where the phase shift amounts are specifically designed to be different for each cell. This asymmetric phase shifting pattern creates a distributed switching strategy that spreads out the harmonic content and reduces concentrated vibration frequencies, thereby minimizing noise while maintaining output quality.
Solution Approach 2:
The converter cells operate with periodic switching based on phase-shifted carrier waves, creating a structured periodic action pattern. By carefully designing the phase shift amounts and switching frequencies, the periodic switching actions of different cells combine to produce high-quality output voltage while the vibration frequencies are distributed across a broader spectrum, reducing audible noise from reactor vibrations.
3Object-generated harmful factors
If phase shifting of carrier waves is implemented, then noise is suppressed, but control complexity increases
Solution Approach 1:
The patent implements noise suppression by changing the phase shift parameter of carrier waves between converter cells. Specifically, different phase shift amounts are applied to different converter cells, which modifies the switching timing and distributes harmonic content. This parameter change approach provides an effective means to suppress noise while maintaining relatively simple control logic compared to more complex multi-variable control strategies.
Data Source
AI summary
The noise generated from a power converter is suppressed by increasing the noise frequency to a level not lower than the maximum frequency of the human audible range. To obtain the frequency of an output current harmonic component as a noise source which has exceeded the maximum frequency of the human audible range, it is adequate to determine that the frequency of a driving carrier wave for the individual converter cells in the power converter, in which the phases of the carrier wave for the converter cells are mutually shifted by a given value between the converter cells, meets the following equation.