EMC Filter Shielding Cavity for On-Board Charger Interference Control
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Solution Overview
Problem
Existing EMC wave filters in on-board chargers for new energy vehicles suffer from electromagnetic leakage and interference due to incomplete shielding, affecting both internal and external environments, and there is a need to enhance electromagnetic shielding performance to reduce interference with peripheral apparatuses and improve EMC stability.
Innovation Solution
A novel EMC wave-filter shielding structure comprising an EMC filter board, lower and upper shield covers, and a connecting holder, which encloses X and Y capacitors, filter inductors, and forms a shielding cavity, connected via screws and thermally-conductive adhesive, independent of the main power circuit board, enhancing vertical space utilization and reducing electromagnetic interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If EMC wave filter apparatuses are directly installed on the main power circuit board inside the housing, then the device complexity is reduced, but electromagnetic shielding performance deteriorates due to gaps between components and housing
Solution Approach 1:
The patent divides the EMC filter components (X capacitor, Y capacitor, filter inductors) into a separate shielded module independent from the main power circuit board. This segmentation allows the filter apparatus to be enclosed in a dedicated shielding cavity with complete electromagnetic shielding, eliminating the gaps that cause interference while maintaining installation simplicity through modular design.
Solution Approach 2:
The patent introduces an independent shielded housing as an intermediary structure between the EMC filter apparatus and the main power circuit board. This intermediate shielding module completely encloses the filter components, blocking electromagnetic fields from affecting the main board while allowing electrical connections to pass through designated apertures with shielding protection.
2Device complexity
If a simple barrier isolation apparatus is used on the housing, then the device complexity is reduced, but the shielding effectiveness is insufficient to cover gaps in horizontal direction
Solution Approach 1:
The shielding structure is segmented into multiple components: a shielded housing enclosing the filter apparatus, a shielded mounting structure on the circuit board, and shielding at connection apertures. Each segment provides localized shielding, and together they form a complete electromagnetic barrier that covers all gaps and openings, ensuring comprehensive shielding effectiveness.
Solution Approach 2:
The patent employs a nested shielding structure where the shielded housing encloses the filter apparatus, which contains the filter components. The mounting structure on the circuit board provides an additional nested shielding layer, and connection apertures have their own shielding. This multi-layer nested approach ensures complete electromagnetic isolation.
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 solution increases the distance between electromagnetic interference sources and control signals, improves control signal quality, reduces the size of the main power board and housing, and enhances EMC stability by minimizing electromagnetic leakage and interference.
Implementation Method 1
a lower shield cover installed on one side of the EMC filter board, and connected with the EMC filter board around to form a shielding cavity; an upper shield cover installed on the other side of the EMC filter board backing toward the shielding cavity, and directly opposite to the lower shield cover
Implementation Method 2
the upper shield cover, the EMC filter board and the lower shield cover are connected with each other as a whole by way of passing a plurality of screws through the through holes, the dodging holes and the threaded holes directly opposite to each other
Data Source
Figure 1~2
Figure 3~4
AI summary
The present invention discloses an EMC wave-filter shielding structure and an EMC wave filter. The structure includes an EMC filter board; a lower shield cover that is installed on one side of the EMC filter board, and connected with the EMC filter board around to form a shielding cavity; a X capacitor, a Y capacitor, a first filter inductor and a second filter inductor that are all arranged in the shielding cavity and correspondingly connected with the EMC filter board, respectively; and an upper shield cover that is installed on the other side of the EMC filter board backing toward the shielding cavity, and directly opposite to the lower shield cover. The EMC wave-filter shielding structure provided by the present invention makes the filter apparatuses independent of a main power circuit board as a whole, increasing the distance between an electromagnetic interference source and a control signal, and enhancing quality of control signals.