Low Inductance Capacitive Filter Assembly for EMI Suppression
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Solution Overview
Problem
Existing EMI filter assemblies are inadequate in reducing radiated emission at power terminal connections, particularly requiring a low inductance capacitive filter solution to effectively suppress unwanted electromagnetic interference.
Innovation Solution
A capacitive filter assembly with a housing having a power terminal connection, where a plurality of capacitors are configured in parallel and coupled to the housing's side walls and printed wiring boards, with support structures mounting them between the power terminal and housing ground connections, enhancing the capacitors' coupling to the housing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional EMI filter assemblies are used, then basic shielding is provided, but radiated emission at power terminal connections is not adequately reduced
Solution Approach 1:
The EMI filter assembly is segmented into multiple parallel capacitive elements (first capacitive element and second capacitive element) with different capacitance values, allowing each segment to target specific frequency ranges. This segmentation enables broader spectrum EMI suppression while maintaining low inductance characteristics, effectively reducing radiated emission without compromising filtering efficiency.
Solution Approach 2:
The invention changes the capacitance parameter by using multiple capacitors with different capacitance values in parallel configuration. This parameter variation allows the filter to effectively handle different frequency components of EMI signals, improving radiated emission reduction across a wider frequency spectrum while maintaining reliable filtering performance.
2Object-affected harmful factors
If capacitive filter assembly is designed to reduce EMI, then electromagnetic interference is suppressed, but inductance must be minimized for high-frequency effectiveness
Solution Approach 1:
The capacitive elements are mounted in a planar arrangement on the circuit board, utilizing the two-dimensional board surface rather than vertical stacking. This dimensional approach minimizes loop areas and trace lengths, thereby reducing parasitic inductance while maintaining effective EMI suppression across high frequencies.
Solution Approach 2:
Multiple capacitive elements with different capacitance values are combined in parallel configuration, merging their filtering effects. This combination achieves broad-spectrum EMI suppression while the compact parallel arrangement minimizes overall inductance, resolving the contradiction between EMI reduction effectiveness and low inductance requirement.
3Manufacturing precision
If multiple capacitors are used in parallel configuration, then high-frequency attenuation is maximized, but manufacturing complexity increases
Solution Approach 1:
The circuit board serves multiple functions: it provides the mounting substrate for capacitive elements, establishes electrical connections through standardized pads and traces, defines the geometric arrangement for optimal EMI suppression, and provides mechanical support. This multi-functionality simplifies manufacturing by consolidating multiple requirements into a single platform, reducing assembly complexity despite using multiple capacitors.
Solution Approach 2:
By selecting standard capacitance values for the parallel capacitive elements, the design achieves optimized high-frequency attenuation while maintaining compatibility with commercially available components. This parameter selection balances manufacturing ease with performance requirements, avoiding custom component specifications that would increase complexity.
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
This configuration effectively reduces electromagnetic interference by maximizing attenuation at high frequencies and securely mounting capacitors to enhance their filtering efficiency.
Implementation Method 1
A plurality of capacitors in an electrically parallel configuration coupled to one or more side walls of the housing
Implementation Method 2
capacitive filter assembly... for reducing electromagnetic interference from power terminal connections
Data Source
AI summary
A capacitive filter assembly and method including a housing having a power terminal connection for receiving electrical power. A plurality of capacitors in an electrically parallel configuration coupled to one or more side walls of the housing. The plurality of capacitors electrically communicating with a plurality of respective printed wiring boards (PWB) coupled to the capacitors inside the housing, and the plurality of capacitors being positioned between the power terminal connection in the housing and respective housing ground connections in the housing. A plurality of support structures coupled to the plurality of capacitors, respectively, the plurality of support structures being configured to mate with the respective printed wiring boards, the support structures being mounted in the housing such that the capacitors are coupled to the housing using their respective support structures.