Temperature-Compensated Noise Filter for Stable Common-Mode Suppression
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Solution Overview
Problem
Conventional noise filters require high costs due to the need for temperature detectors and controllers to maintain noise suppression effectiveness as resonance frequencies change with temperature.
Innovation Solution
A noise filter design where the temperature dependence of the product of inductance and capacitance values in the main circuit portion and the filter part are equal, eliminating the need for temperature detectors and controllers by ensuring consistent noise suppression across temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a temperature detector and controller are added to maintain noise suppression effectiveness, then noise suppression reliability is improved, but device cost and complexity increase
Solution Approach 1:
The noise filter is designed to automatically maintain noise suppression effectiveness through inherent circuit characteristics. The feedback circuit monitors the actual noise suppression performance and automatically adjusts the filter parameters without requiring external temperature detectors or controllers, making the system self-regulating and eliminating additional components.
Solution Approach 2:
A feedback circuit is incorporated that detects the noise suppression effectiveness and feeds this information back to automatically adjust the filter characteristics. This closed-loop control ensures consistent noise suppression across temperature variations while avoiding the need for separate temperature sensing and control systems.
2Reliability
If a temperature detector and controller are added to maintain noise suppression effectiveness, then noise suppression reliability is improved, but manufacturing cost increases
Solution Approach 1:
The noise filter is designed to automatically maintain noise suppression effectiveness through inherent circuit characteristics. The feedback circuit monitors the actual noise suppression performance and automatically adjusts the filter parameters without requiring external temperature detectors or controllers, making the system self-regulating and eliminating additional components.
Solution Approach 2:
The invention replaces expensive temperature detectors and controllers with a simpler feedback circuit using basic electronic components that are cheaper and easier to manufacture. The feedback mechanism uses standard resistors, capacitors, and operational amplifiers rather than specialized temperature sensing and control hardware.
3Reliability
If the resonance frequency changes with temperature, then the filter must be adjusted to maintain effectiveness, but this increases device complexity
Solution Approach 1:
A feedback circuit is incorporated that detects the noise suppression effectiveness and feeds this information back to automatically adjust the filter characteristics. This closed-loop control ensures consistent noise suppression across temperature variations while avoiding the need for separate temperature sensing and control systems.
Solution Approach 2:
The noise filter is designed to automatically maintain noise suppression effectiveness through inherent circuit characteristics. The feedback circuit monitors the actual noise suppression performance and automatically adjusts the filter parameters without requiring external temperature detectors or controllers, making the system self-regulating and eliminating additional components.
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 noise filter maintains effective noise suppression without the need for temperature detectors and controllers, reducing costs while maintaining performance across varying temperatures.
Implementation Method 1
a noise detection unit which detects a common mode noise on an electrical path
Implementation Method 2
a resonance based on an inductance component of the choke coil and a capacitive component on the electrical path is generated
Implementation Method 3
The magnetic permeability of a core material of the choke coil changes according to the temperature of the choke coil
Data Source
AI summary
Provided is a low-cost noise filter having a noise suppression effect that is not reduced even when a resonance frequency changes according to changes in temperature. A noise filter includes: a noise detection unit which detects a common mode noise; a cancellation signal output unit; an injection unit which injects a cancellation signal; and a grounded capacitor. The cancellation signal output unit includes a filter part which generates the cancellation signal from the common mode noise, and an amplification part which amplifies the cancellation signal. A temperature dependence of a product of an inductance value and a capacitance value of a main circuit portion including the noise detection unit, the injection unit, and the grounded capacitor, and a temperature dependence of a product of an inductance value and a capacitance value of the filter part, are equal to each other.