Broadband Filter for Three-Phase AC Power Noise Suppression
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Solution Overview
Problem
Existing three-phase AC power filters are ineffective in filtering noise across a broad frequency range due to capacitors' limitations in filtering both low and high frequency noise, resulting in limited filtering bands and interference with connected devices.
Innovation Solution
A broadband filter design incorporating multiple capacitors and inductors for differential-mode and common-mode noise filtering, where specific capacitors and inductors are used to filter low and high frequency noise separately, effectively increasing the filtering bandwidth and reducing noise interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single capacitor is used for filtering in the differential-mode filtering circuit and common-mode filtering circuit, then the device complexity is reduced, but the filtering bandwidth is limited and cannot effectively filter both low frequency and high frequency noise
Solution Approach 1:
The patent divides the filtering function into multiple segments by using separate capacitors for different frequency ranges. Specifically, it uses a first capacitor (C1) tuned for low frequency noise and a second capacitor (C2) tuned for high frequency noise in the differential-mode filtering circuit, and similarly divides the common-mode filtering circuit into multiple capacitors (C3, C4, C5) for different frequency ranges. This segmentation allows each capacitor to be optimized for its specific frequency band, thereby expanding the overall filtering bandwidth while maintaining manageable circuit complexity.
Solution Approach 2:
The patent creates a multi-functional filtering system where multiple capacitors work together to provide both low frequency and high frequency noise filtering capabilities within a single filter device. The differential-mode filtering circuit uses capacitors C1 and C2 to handle both low and high frequency differential-mode noise, while the common-mode filtering circuit uses capacitors C3, C4, and C5 to handle common-mode noise across the frequency spectrum. This multi-functionality allows the filter to adapt to various noise conditions without requiring separate filtering circuits.
2Reliability
If capacitors with different equivalent series inductance and equivalent series resistance are used, then the filtering performance for specific frequency ranges is improved, but the filtering capability across the full frequency spectrum deteriorates
Solution Approach 1:
The patent applies local quality by assigning specific capacitor characteristics to specific frequency ranges. The first capacitor (C1) is designed with equivalent series inductance and equivalent series resistance optimized for low frequency noise filtering, while the second capacitor (C2) is designed with different equivalent series inductance and equivalent series resistance optimized for high frequency noise filtering. Similarly, capacitors C3, C4, and C5 in the common-mode filtering circuit are each optimized for their respective frequency ranges. This local optimization ensures that each capacitor delivers reliable filtering performance for its target frequency range.
Solution Approach 2:
The patent utilizes parameter changes by varying the equivalent series inductance and equivalent series resistance parameters of different capacitors to match different frequency requirements. By changing these parameters across the capacitor array, the system achieves broad frequency coverage. The first capacitor (C1) has parameters suited for low frequency operation, while the second capacitor (C2) has parameters optimized for high frequency operation, allowing the filter to maintain reliable performance across the entire frequency spectrum through parameter diversification.
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 broadband filter effectively suppresses noise across a wide frequency range, minimizing interference and enhancing the performance of three-phase AC power systems by allowing both low and high frequency noise to be filtered simultaneously.
Implementation Method 1
The first capacitor C1l, the first inductor L1, and the second inductor L2 filter low frequency differential-mode noise over the live wire L and the neutral wire N
Implementation Method 2
The second capacitor C1h, the first inductor L1, and the second inductor L2 filter high frequency differential-mode noise over the live wire L and the neutral wire N
Implementation Method 3
The third capacitor C2l, the third inductor L3, and the fourth inductor L4 filter low frequency common-mode noise over the live wire L and the neutral wire N
Implementation Method 4
The fourth capacitor C2h, the third inductor L3, and the fourth inductor L4 filter high frequency common-mode noise over the live wire L and the neutral wire N
Data Source
AI summary
A broadband filter filtering noise over a first conductive wire, a second conductive wire, and a third conductive wire includes a differential-mode filtering circuit connected to both the first conductive wire and the second conductive wire and a common-mode filtering circuit connected to both the first conductive wire and the second conductive wire. The differential-mode filtering circuit includes two inductors and two capacitors for filtering differential-mode noise of different frequencies. The common-mode filtering circuit includes two inductors and six capacitors filtering common-mode noise of different frequencies.