Electromagnetic Noise Compensation Loop for Stable Feedback Control

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Solution Overview

Problem

Existing noise reduction devices using feedback control methods face instability and limited noise reduction effectiveness due to phase delay-induced noise amplification, which can cause oscillation and hinder high noise reduction while maintaining stability.

Innovation Solution

A noise reduction device incorporating a noise detector, compensation signal generator, injector, detector, low-frequency component subtraction unit, and intermediate frequency component addition unit, employing negative minor feedback for low-frequency components and positive minor feedback for intermediate frequency components to stabilize the feedback control loop and enhance noise reduction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the gain of the feedback loop is increased to enhance the noise reduction effect, then the noise reduction effectiveness is improved, but the noise amplified signal caused by phase delay increases, leading to oscillation and instability

Engineering Contradiction:
Improvenoise reduction effectVSAvoidoperational stability
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent segments the feedback control into two independent control loops: a main feedback loop for overall noise reduction and a minor feedback loop specifically for suppressing noise amplified signals. This segmentation allows each loop to be optimized for its specific function without interfering with the other, resolving the contradiction between noise reduction effectiveness and operational stability

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces a minor feedback loop that detects noise amplified signals and feeds back compensation to suppress them. This additional feedback mechanism specifically targets the instability caused by phase delay without compromising the overall noise reduction performance, enabling both high noise reduction effect and operational stability

Inventive Principle:
Principle #23Feedback

2Reliability

If feedback control is used to reduce noise, then noise reduction effectiveness is improved, but phase delay causes noise amplification that leads to oscillation

Engineering Contradiction:
Improvenoise reduction effectivenessVSAvoidnoise amplified signal
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent converts the harmful noise amplified signal into a useful control parameter by detecting it through the noise detector and using it as feedback in the minor feedback loop. This allows the system to specifically target and suppress the harmful phase delay effects while maintaining the beneficial noise reduction from the main feedback loop

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent introduces an intermediary minor feedback loop that acts as a mediator between the main feedback loop and the noise amplified signals. This intermediary loop processes specifically the noise amplified components and provides targeted compensation, preventing them from causing oscillation while allowing the main loop to maintain overall noise reduction effectiveness

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP4131755B1Noise reduction device
Publication Date: 2024.07.17 MITSUBISHI ELECTRIC CORP
  • EP4131755B1 patent drawingFigure 1
  • EP4131755B1 patent drawingFigure 2
  • EP4131755B1 patent drawingFigure 3

AI summary

A compensation signal generator (60) generates a compensation signal (icmp) for canceling an electromagnetic noise on a connection line (m0) on the basis of a detection signal (vsns) of a noise detector (20). A compensation signal injector (80) injects the compensation signal (icmp) into the connection line (m0). A compensation signal detector (70) outputs a detection signal (vcmp) of the compensation signal (icmp). A low-frequency component subtraction unit (50) amplifies a component in a predetermined first frequency region of the detection signal (vcmp) and negatively feeds back the amplified component to the compensation signal generator (60). An intermediate frequency component addition unit (30) positively feeds back a component of a predetermined second frequency that is higher than the first frequency region in the detection signal (vsns) to the compensation signal generator (60).