Power Conversion Device Noise Suppression via Quarter-Wavelength Conductive Member
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Solution Overview
Problem
Transistors and Zener diodes in existing noise reduction devices for power conversion systems are unable to operate at high speeds for high-frequency switching noise, thereby failing to effectively suppress noise.
Innovation Solution
A power conversion device incorporating a conductive member made of electrically conductive material attached to the housing, configured to reflect and cancel out noise waves propagating through the housing, utilizing specific lengths and configurations to interfere with and attenuate noise frequencies matching those generated by switching operations in the power module.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If transistors and Zener diodes are used for noise reduction, then noise suppression is achieved, but high-frequency switching noise cannot be suppressed due to slow operation speed
Solution Approach 1:
The patent extracts the noise suppression function from active electronic components (transistors and Zener diodes) and implements it through a passive conductive member with specific geometric configuration. The conductive member is shaped to create specific impedance characteristics that reflect and cancel high-frequency noise waves without requiring active switching operation, thereby achieving both noise suppression and high-frequency response.
Solution Approach 2:
The patent changes the approach from active component parameter tuning to passive structural parameter optimization. By carefully designing the length, width, and position of the conductive member on the housing, the system achieves frequency-selective noise cancellation. The dimensions are specifically chosen to create quarter-wavelength or half-wavelength resonant structures that target high-frequency switching noise.
2Object-affected harmful factors
If active noise compensation circuits are used, then noise current is reduced, but device complexity increases
Solution Approach 1:
The patent extracts the essential noise cancellation function from complex active circuits and implements it through a simple passive conductive structure. The conductive member alone, with appropriate geometric dimensions, provides the noise suppression function without requiring transistors, diodes, or control circuits, thereby significantly reducing device complexity.
Solution Approach 2:
The conductive member performs noise suppression autonomously through its inherent electromagnetic properties and geometric configuration. It automatically reflects and cancels noise waves based on its physical structure and the incident noise characteristics, without requiring external control signals, power supply, or active management, thus eliminating the need for complex control circuits.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The conductive member effectively suppresses and prevents leakage of noise from the housing by reflecting and canceling out noise waves, thereby reducing noise propagation and radiation.
Implementation Method 1
the conductive member 2 reflects the noise and cancels out the noise
Implementation Method 2
configured to reflect and cancel out noise waves propagating through the housing, utilizing specific lengths and configurations to interfere with and attenuate noise frequencies
Data Source
Figure 1
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AI summary
A power conversion device includes a power module (5) which switches a switching element between ON and OFF states thereby to convert power inputted to the power module (5) and to output the converted power, a housing (3) made of metal, which houses the power module (5), and a conductive member (2) connected to the housing (3). The conductive member (2) is connected to the housing (3) at a position at which a length thereof from an open end is nλ/4, where "n" is an odd number equal to or more than 1, and "λ" is a wavelength of noise produced by switching the switching element between the ON and OFF states.