EMI Suppression Circuit for Differential-Mode Noise Sensing
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Solution Overview
Problem
Existing electromagnetic interference suppression circuits struggle to effectively cancel conducted differential mode electromagnetic interference signals due to interference from the power source, which degrades suppression performance.
Innovation Solution
The proposed electromagnetic interference suppression circuit includes a sensing circuit with a gain factor, an amplifier, and a controlled voltage source, arranged in a loop to detect and counteract differential mode electromagnetic interference signals while minimizing interference from the power source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sensing circuit is connected across the power lines to detect electromagnetic interference signals, then the suppression performance can be improved by generating an accurate suppression signal, but the sensing circuit will pick up interference signals from both the electronic circuit and the power source, causing the picked-up power source interference to degrade the suppression performance
Solution Approach 1:
The patent divides the sensing function into two separate sensing circuits: one connected across the power lines to detect interference from the electronic circuit, and another connected across the power source to detect interference from the power source. This segmentation allows each sensing circuit to focus on a specific interference source, preventing the mixing of interference signals and enabling independent processing and cancellation of each type of interference, thereby resolving the contradiction between achieving accurate suppression and avoiding power source interference contamination.
2Measurement precision
If the sensing circuit is placed close to the electronic circuit to accurately detect interference signals, then the detection accuracy improves, but the circuit complexity and potential interference from the power source increase
Solution Approach 1:
The patent segments the detection system into two spatially separated sensing circuits with distinct functions. One sensing circuit is positioned near the electronic circuit to detect its emitted interference, while the other is positioned near the power source to detect power source interference. This spatial segmentation simplifies each individual sensing circuit's function and reduces the complexity of signal processing, as each circuit only needs to handle one type of interference signal rather than filtering multiple mixed signals.
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 configuration enhances the immunity to interference signals from the power source, leading to improved suppression performance and effective reduction or elimination of conducted differential mode electromagnetic interference signals.
Implementation Method 1
a sensing circuit 102 that is connected on a supply power line and is arranged in series between the capacitor Cx and the electronic circuit 30... adapted to detect the electromagnetic interference signal Vn to be suppressed across the capacitor Cx
Implementation Method 2
an amplifier 104... adapted to amplify the sensed signal Vs so as to produce an amplified sensed signal Vsa
Implementation Method 3
a controlled voltage source 106... adapted to generate a suppression signal Vn' in response to the amplified sensed signal Vsa... prevents the interference signal Vn from propagating into the power source 20
Data Source
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AI summary
An electromagnetic interference suppression circuit and a related sensing circuit. The sensing circuit includes an input and an output operatively coupled with the input. The input is adapted to be connected on a power line and in series between a load and a shunt circuit connected across power lines between a power source and the load. The output is adapted to provide a signal (V s) associated with an electromagnetic interference signal (V n) generated by or at the load and arranged to be experienced by the shunt circuit. The signal (V s) can be used for determining a suppression signal (V n') for reducing, or substantially eliminating, the electromagnetic interference signal (V n). The electromagnetic interference suppression circuit includes the sensing circuit, a regulator circuit, and a controlled signal source.