Multi-Stage DC Bus Filter Circuit for SiC EMI and Low Insertion Loss
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Solution Overview
Problem
The 800 V high-voltage and high-power density electric drive controllers face significant electromagnetic interference issues due to the use of third-generation wide bandgap silicon carbide (SiC) power semiconductors, leading to high stray inductance, high filter insertion loss, and inflexible volume structures, which hinder their widespread application.
Innovation Solution
A filter circuit and filter design for direct-current power supplies that includes multiple stages of filter magnetic rings and capacitors, integrated with differential-mode and common-mode circuits, to eliminate electromagnetic interference while providing power and boosting functions, reducing insertion loss and meeting strict filtering requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional filter structures are used in 800V high-voltage electric drive controllers, then electromagnetic interference filtering is provided, but stray inductance increases and filter insertion loss becomes high
Solution Approach 1:
The filter structure is divided into multiple independent filter units, each with its own magnetic ring and capacitor. These units are distributed along the positive and negative direct current buses and charging lines, allowing the filtering function to be segmented across multiple locations rather than concentrated in a single high-inductance structure
Solution Approach 2:
The filter transitions from a traditional series configuration to a distributed multi-dimensional arrangement. Filter units are placed at different positions along the power lines (input terminals, output terminals, and intermediate positions), creating a spatial distribution that reduces the inductance of any single filter element while maintaining overall filtering effectiveness
2Power
If traditional filter designs are applied, then power supply function is provided, but the volume structure becomes inflexible
Solution Approach 1:
The filter is segmented into multiple independent units that can be individually positioned along the power lines. Each unit consists of a filter magnetic ring and capacitor connected in parallel, allowing flexible arrangement to adapt to different spatial constraints and power distribution configurations
Solution Approach 2:
The same filter unit design (magnetic ring with parallel capacitor) is used universally across all three power lines (positive bus, negative bus, charging line). This standardized modular approach provides both power supply and filtering functions while allowing flexible volume configuration through selective placement of identical units
3Object-affected harmful factors
If multiple stages of filter circuits are implemented, then filtering performance improves, but device complexity increases
Solution Approach 1:
The filtering function is segmented into multiple simple identical units rather than one complex multi-stage filter. Each unit contains a magnetic ring and capacitor in parallel, and the segmentation allows achieving better filtering performance through distributed placement while keeping each individual unit simple and easy to manufacture
Solution Approach 2:
Instead of using a traditional approach where multiple filter stages are connected in series with increasing complexity, this invention inverts the approach by using multiple simple filter units connected in parallel across different power lines. The filtering effect is achieved through the combined action of these simple units rather than through a complex sequential arrangement
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 design achieves high resistance to insertion loss, stable signal transmission, and meets stringent filtering needs, with a compact structure and low maintenance costs, enhancing the performance and applicability of electric drive controllers.
Implementation Method 1
at least three stages of filter circuits, respectively connected between the positive direct-current bus input terminal and the positive direct-current bus output terminal
Implementation Method 2
the at least three stages of filter circuits further include multiple direct-current support capacitors respectively connected between the positive direct-current bus and a ground terminal
Data Source
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AI summary
The present application discloses a filter circuit of a direct-current power supply, a filter, an electric drive controller, and an automobile. The filter circuit of the direct-current power supply comprises a positive direct-current bus, a negative direct-current bus, a charging cable, and a filter circuit having at least three stages. The positive direct-current bus comprises a positive direct-current bus input end and a positive direct-current bus output end. The negative direct-current bus comprises a negative direct-current bus input end and a negative direct-current bus output end. The charging cable comprises a charging cable input end and a charging cable output end. Said filter circuit is separately connected between the positive direct-current bus input end and the direct-current bus output end, between the negative direct-current bus input end and the negative direct-current bus output end, and between the charging cable input end and the charging cable output end.