DC Link Dampener With Isolated Common and Differential Mode Filtering
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Solution Overview
Problem
Existing common mode and differential mode filters cannot effectively dampen both transients due to the use of the same resistance for both modes, leading to inadequate suppression of common mode and differential mode transients in DC links.
Innovation Solution
A common mode and differential mode filter design with separate damping resistances, where the differential mode damping resistance is distinct from the common mode damping resistance, utilizing a three-wire choke to isolate common mode damping resistance from differential mode transients, and inductors connected in series with both DC rails to provide independent filtering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the same resistance is used for both common mode and differential mode filtering, then the filter structure is simple, but the filtering effectiveness for both modes is inadequate
Solution Approach 1:
The filter is segmented into two independent resistance components: a first resistance specifically for common mode transient damping and a second resistance specifically for differential mode transient damping. This segmentation allows each resistance to be independently optimized for its respective mode, resolving the contradiction by maintaining structural simplicity while achieving effective filtering for both modes simultaneously.
Solution Approach 2:
Different resistance values are assigned to different filtering modes based on their specific requirements. The first resistance is configured with a value optimized for common mode transient damping, while the second resistance is configured with a different value optimized for differential mode transient damping. This local quality approach ensures that each part of the filter performs its specific function effectively.
2Reliability
If separate damping resistances are used for common mode and differential mode filtering, then the filtering effectiveness is improved, but the device complexity increases
Solution Approach 1:
The common mode filter and differential mode filter are merged into a single integrated filter unit that processes both modes simultaneously. The first inductor and second inductor are combined in the circuit architecture, and both resistance components are integrated into the same filter structure, achieving effective filtering for both modes without requiring separate independent filter systems.
Solution Approach 2:
The filter is designed with multi-functionality to handle both common mode and differential mode transients within a single device. The inductors and resistances are configured to serve dual purposes: the first inductor and second inductor work together for both modes, while the two resistance components provide specialized damping for each mode, achieving universal filtering capability.
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 design allows for tailored suppression of differential mode and common mode transients, enhancing the filtering effectiveness by allowing independent adjustment of resistance values for each mode, thereby improving transient damping in DC links.
Implementation Method 1
The common mode damping resistance is galvanically isolated from differential mode transients flowing through the differential mode damping resistance
Implementation Method 2
Filters are used to dampen transients between links such as DC links. The transients may be in the form of ringing or resonance caused by the inductance of a cable connecting an external device and capacitance on the DC bus(es).
Data Source
AI summary
A common mode and a differential mode filter(s) between DC links are provided. Each link has a positive rail and a negative rail. The filter comprises a first inductor respectively connected to each of the positive rail and the negative rail, differential mode damping resistance connected in parallel to each of the first inductor, respectively, and a three-wire choke. The three-wire choke comprises a first wire connected in series with the differential mode damping resistance parallel to the positive rail, a second wire connected in series with the differential mode damping resistance parallel to the negative rail and a third wire connected to common mode damping resistance. The common mode damping resistance is galvanically isolated from differential mode transients flowing through the differential mode damping resistance. The differential mode filter has the differential mode damping resistance, and the common mode filter has the common mode damping resistance.