Asymmetric Filter Circuit Layout for EV Charging EMI Limits
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electrical filter circuits for electric vehicles face challenges in meeting stringent electromagnetic interference (EMI) emission limits during DC fast charging, particularly in booster mode, while being constrained by safety regulations that limit the total capacity of capacitors.
Innovation Solution
An asymmetric electrical filter circuit is designed with an x-capacitor and two y-capacitors, allowing larger y-capacitor values without exceeding safety limits, supplemented by a common mode choke for additional filtering, thereby reducing EMI emissions effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a symmetrical filter circuit with y-capacitors is used to filter all 3 charging connection lines, then electromagnetic interference emissions are reduced, but the total capacitor capacity exceeds safety limits
Solution Approach 1:
The patent applies asymmetry by configuring the filter circuit differently for each charging connection line based on their specific EMI characteristics. The first and third lines (positive pole of high voltage battery and positive pole of charging voltage) are equipped with y-capacitors, while the second line (negative pole) uses an x-capacitor instead, creating an asymmetric filter topology that optimizes EMI suppression while respecting capacitor capacity limits.
Solution Approach 2:
The patent implements local quality by assigning different capacitor types and values to different lines based on their specific EMI emission characteristics. The first y-capacitor on the positive pole line has a different capacity than what would be used on other lines, tailored to the specific EMI reduction needs of that particular connection line during booster mode operation.
2Object-affected harmful factors
If larger y-capacitor values are used to reduce EMI emissions, then electromagnetic interference suppression is improved, but installation space and cost increase
Solution Approach 1:
The asymmetric filter configuration allows optimization of capacitor sizes for each line based on actual EMI needs rather than using uniform large capacitors on all lines. This reduces the total installation space required while maintaining effective EMI suppression where most needed.
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 asymmetric filter design achieves efficient EMI suppression with reduced capacitor capacity, requiring less installation space, weight, and cost, while maintaining effective filtering performance.
Implementation Method 1
The filter circuit (100) comprises an x-capacitor (CX_i), a first and a second y-capacitor (CY1_i, CY2_i). The x-capacitor (CX_i) is connected between the first and third filter output terminals (212, 216) or the first and third filter input terminals (213, 217). The first y-capacitor (CY1_i) is connected between the third filter output terminal (216) or the third filter input terminal (217) and a reference potential or ground. The second y-capacitor (CY2_i) is connected between the second filter output terminal (214) or the second filter input terminal (215) and a reference potential or ground.
Implementation Method 2
supplemented by a common mode choke for additional filtering, thereby reducing EMI emissions effectively
Data Source
AI summary
The present invention creates an electrical filter circuit (100) for an electric drive (200), wherein the filter circuit (100) comprises an x-capacitor (CX_i), a first and a second y-capacitor (CY1_i, CY2_i). The x-capacitor (CX_i) is connected between a first and the third filter output terminal (212, 216), or a first and a third filter input terminal (213, 217), and the first y-capacitor (CY1_i) is connected between the third filter output terminal (216) or the third filter input terminal (217) and a reference potential or ground. The second y-capacitor (CY2_i) is connected between the second filter output terminal (214) or the second filter input terminal (215) and a reference potential or ground.