DC Common-Mode Filtration Using Energy Capture and Storage
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Solution Overview
Problem
Current solutions for reducing common mode noise in power systems, such as Y-capacitors and chokes, either increase harmonic content on the AC side or are insufficient in damping, and are not suitable for all applications, particularly in drive systems and vessels.
Innovation Solution
A power filtration system that filters common mode signals from a DC conductor, dissipating the energy through a load or conducting it to an energy storage device, using a first filter, rectifier, and smoothing circuit to minimize common mode signals and harmonic content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If Y-capacitors are used to reduce common mode currents on the DC side, then common mode noise is decreased, but harmonic content on the AC side increases
Solution Approach 1:
The patent captures the common mode currents that would otherwise be harmful noise and converts them into usable energy by directing them to charge energy storage devices such as capacitors or batteries. This transforms the harmful common mode energy into a beneficial resource, simultaneously reducing common mode noise on the DC side without increasing harmonic content on the AC side, as the energy is stored rather than dissipated or transferred to the AC grid
Solution Approach 2:
The patent introduces an intermediary energy storage device between the common mode current path and the AC/DC conversion process. This intermediary captures the common mode energy before it can affect the AC side, allowing the system to reduce common mode noise independently of the AC harmonic content. The energy storage device acts as a buffer that decouples the common mode suppression function from the AC power quality
2Object-affected harmful factors
If common mode chokes are used to dampen common mode currents, then some common mode noise is reduced, but the damping amount is limited and often insufficient
Solution Approach 1:
The patent changes the fundamental parameter of common mode current handling from passive damping (chokes) to active energy capture and storage. Instead of relying on the limited impedance of chokes to dampen currents, the system uses active circuitry to redirect and store the common mode energy, dramatically increasing the effectiveness of common mode suppression beyond what passive damping components can achieve
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 system effectively reduces common mode noise without increasing harmonic content on the AC side, improving efficiency by harnessing the common mode signals for energy storage.
Implementation Method 1
The first filter is connected to the DC conductor and configured to pass the common mode signal
Implementation Method 2
The rectifier circuit is connected to the filter circuit and is configured to rectify the common mode signal from the first filter to produce a rectified signal
Implementation Method 3
The smoothing filter circuit is connected to the rectifier circuit and is configured to smooth the rectified signal to produce a generally DC signal
Implementation Method 4
The load is configured to dissipate the energy of the common mode signal
Implementation Method 5
The power circuit is configured to conduct the common mode signal to an energy storage device
Data Source
AI summary
A power filtration system filters out a common mode signal from a DC conductor of a power system. The power filtration system comprises a first filter and at least one of a load or a power circuit. The first filter is connected to the DC conductor and configured to pass the common mode signal. The load is configured to dissipate the energy of the common mode signal. The power circuit is configured to conduct the common mode signal to an energy storage device.