EMI Filter Impedance Matching via Direct Load Measurement
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Solution Overview
Problem
Existing electronic circuit designs face challenges in accurately matching the impedance of EMI filters with load circuits, leading to inefficient test processes and unsatisfactory design outcomes due to theoretical parameter settings.
Innovation Solution
A measuring system comprising an impedance measuring chip with a direct digital synthesizer, analog digital converter, and digital signal processor is used to calculate the actual impedance of a load circuit, providing accurate impedance data for matching the EMI filter parameters, including a frequency sweeper or spectrum analyzer for reading and processing the impedance data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If theoretical simulation method is used to obtain load impedance for EMI filter parameter setting, then design process is simplified, but impedance matching accuracy deteriorates
Solution Approach 1:
The patent replaces the traditional theoretical simulation method with an actual measurement system. The measuring system directly measures the load impedance of the power supply module using electrical measurement techniques, substituting the mechanical/theoretical design process with empirical measurement to achieve accurate impedance matching.
Solution Approach 2:
The patent implements a feedback mechanism where the measured load impedance is fed back to guide the EMI filter parameter setting. The measuring system provides actual impedance data that is used to optimize the EMI filter design, creating a closed-loop process that improves matching accuracy while maintaining design efficiency.
2Adaptability or versatility
If iterative testing and modification approach is used to achieve electromagnetic compatibility, then design adaptability is improved, but development time increases
Solution Approach 1:
The patent performs preliminary measurement of the load impedance before EMI filter design and testing. By obtaining accurate impedance data in advance through the measuring system, the design process can proceed directly with optimized parameters rather than requiring multiple iterative tests and modifications, significantly reducing development time while maintaining adaptability.
3Ease of manufacture
If typical EMI filter is added to power supply module without impedance matching, then electromagnetic interference suppression is attempted, but filtering effectiveness deteriorates
Solution Approach 1:
The patent changes the parameters of the EMI filter based on actual measured impedance data. Instead of using fixed typical values, the filter parameters (such as capacitor and inductor values) are optimized according to the real load impedance characteristics, achieving effective filtering while maintaining ease of implementation through a systematic parameter selection method.
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 approach simplifies the test process, enhances the accuracy of impedance matching, reduces development time and costs, and facilitates precise circuit design by directly measuring impedance at a single board level, ensuring better alignment between the EMI filter and actual circuit impedance.
Implementation Method 1
the impedance measuring chip... is configured to output an excitation voltage to the load circuit, receive a current returned by the load circuit, calculate an impedance of the load circuit based on the excitation voltage and the current returned by the load circuit
Implementation Method 2
a frequency of the excitation voltage is a frequency corresponding to a noise peak of the power supply module
Implementation Method 3
the analog digital converter is configured to, after the load circuit returns the current, sample the current to transfer to the digital signal processor
Implementation Method 4
the digital signal processor is configured to perform discrete Fourier transform on the sampled current, calculate the impedance of the load circuit based on the excitation voltage and the discrete-Fourier-transformed current
Data Source
Figure 1~2
AI summary
A measuring system for implementing impedance matching of an electromagnetic immunity filter comprises an impedance measuring chip, an impedance reading device, and a power supply module and a load circuit in a circuit to be applied by the electromagnetic immunity filter; wherein, the impedance measuring chip, connected between the power supply module and the load circuit, is configured to output an excitation voltage to the load circuit, receive a current returned by the load circuit, calculate an impedance of the load circuit based on the excitation voltage and the current returned by the load circuit, and output the impedance to the impedance reading device; and the impedance reading device is configured to read the impedance calculated by the impedance measuring chip. Accordingly, the present invention further provides a method for implementing impedance matching of an electromagnetic immunity filter. Using the present invention, a test process is greatly simplified, pertinence of test results is strong, an impedance of a single board may be measured directly so as to provide the impedance of a network element system composed of different single boards.