EMC-filter
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Solution Overview
Problem
Passive EMC filters used in electric refrigerant compressors of motor vehicles face challenges with high core losses and heating issues due to high input currents, leading to inefficient interference suppression and increased power losses, especially in differential mode chokes with ferrite cores.
Innovation Solution
The design incorporates a choke with a copper bus bar winding and a ferrite core split into multiple parts, with planar or convex heat transfer areas for improved heat dissipation, using a thermally conductive paste or gap pad for enhanced cooling and securement, allowing for efficient heat transfer to the housing of the refrigerant compressor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ferrite core is used in a differential mode choke for EMC filtering, then the filter effectiveness is improved, but core losses increase and heating problems occur due to high input currents
Solution Approach 1:
The ferrite core is divided into multiple separate core segments (first core segment, second core segment, etc.) that are arranged around different portions of the winding. This segmentation reduces the overall core volume and consequently reduces core losses while maintaining sufficient filtering effectiveness for differential mode interferences.
Solution Approach 2:
Different core segments are positioned at specific locations around the winding based on local magnetic field requirements. The core segments provide magnetic shielding and flux containment only where needed, rather than using a complete surrounding core structure, thereby reducing unnecessary core material and associated losses.
2Reliability
If a complete ferrite core surrounds the winding, then magnetic shielding is improved, but installation space increases and costs rise
Solution Approach 1:
The core structure is segmented into multiple discrete core segments positioned at strategic locations around the winding. This provides adequate magnetic shielding for EMC filtering while significantly reducing the total volume of ferrite material required compared to a complete surrounding core.
Solution Approach 2:
Unnecessary portions of the core are removed from the design. Only the essential core segments required for effective differential mode filtering are retained, eliminating excess core material that would increase installation space without providing additional filtering benefit.
3Power
If high input currents flow through the choke, then the load-carrying capacity is improved, but core losses increase and heating occurs
Solution Approach 1:
The segmented core structure reduces total core volume and consequently reduces core losses (hysteresis and eddy current losses) that generate heat. This allows the choke to handle high input currents with reduced temperature rise compared to a complete core design.
Solution Approach 2:
Excess core material that contributes to heat generation is removed. The minimal core segments provide sufficient magnetic circuit functionality for filtering while minimizing I²R losses and hysteresis losses that cause heating, enabling better thermal management under high current conditions.
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 reduces core losses, increases the load-carrying capacity, saves installation space, and lowers costs by effectively dissipating heat and maintaining reliable operation of the EMC filter.
Implementation Method 1
The EMC filter (1) is characterized in that the core (10) is comprised of at least two core segments (10), arranged around a winding of the choke (4).
Data Source
AI summary
The invention which relates to an EMC filter (1) addresses the problem of specifying an EMC filter (1) that is simple of structure, cost-effective and temperature resistant. This problem is resolved thereby that the core of the choke (4, 5) is comprised of one or two core parts (10), that at least one first planar or convex heat transfer area (23) is located on an outside of the core and that the core with this first planar or convex heat transfer area (23) is disposed on a housing (12) of the refrigerant compressor, wherein the housing (12) in the region of the first planar or convex heat transfer area (23) is implemented planar or concave.