Passive-Device Impedance Fitting for Resonant-Band EMI Modeling
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Solution Overview
Problem
Existing impedance modeling methods for passive devices in high-power power electronic devices, such as those in fuel cell vehicles, suffer from inaccuracies and non-convergence issues, leading to ineffective electromagnetic interference suppression due to significant differences between simulated and actual impedance characteristic curves.
Innovation Solution
A method involving dividing the impedance characteristic curve into resonant wavebands, determining appropriate RLC parallel circuit models for each waveband, and performing iterative optimization to minimize errors, resulting in an equivalent impedance model that accurately represents the passive device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If parameter extraction is performed based on vector fitting, then model parameters can be obtained, but the solution easily has non-convergence and may produce negative results
Solution Approach 1:
The impedance characteristic curve is divided into multiple resonant wavebands, each processed independently with appropriate RLC models. This segmentation allows each sub-problem to be solved more reliably while maintaining overall accuracy across the full frequency range.
Solution Approach 2:
The patent transforms the parameter extraction problem from a direct vector fitting approach to an iterative optimization process that adjusts RLC parameters to minimize error between simulated and measured impedance curves. This parameter transformation approach avoids the non-convergence issues of traditional vector fitting.
2Device complexity
If a single RLC model is used for the entire impedance curve, then the model structure is simple, but there is a significant difference between simulated and actual impedance characteristic curves
Solution Approach 1:
The impedance spectrum is divided into multiple resonant wavebands, with each waveband modeled by appropriate RLC circuit structures. This segmentation enables accurate representation of different resonant characteristics while maintaining manageable model complexity through modular processing.
Solution Approach 2:
Different RLC model configurations are applied to different resonant wavebands based on their specific characteristics. Conventional resonant peaks use standard RLC parallel circuits, while wide resonant peaks use cascaded RLC structures, optimizing local model accuracy for each region.
3Measurement precision
If iterative optimization is performed for each resonant waveband, then modeling accuracy is improved, but the calculation process becomes more complex
Solution Approach 1:
The optimization process is divided into independent stages for each resonant waveband, reducing the complexity of each optimization sub-problem while achieving cumulative accuracy improvement across the full frequency range through systematic processing of multiple segments.
Data Source
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AI summary
Provided are a passive-device impedance fitting method and apparatus, and an electronic device and a storage medium. The method comprises: acquiring an impedance characteristic curve obtained by means of actual measurement; dividing the impedance characteristic curve to obtain M resonant wavebands arranged in sequence, wherein an impedance model corresponding to a wide resonant peak is p groups of RLC parallel circuits that are connected in series, p being an integer greater than or equal to 2; performing iterative optimization through a preset optimization algorithm based on the initial parameter of an i-th impedance model and a corresponding optimization floating range, and using a group of parameters that is obtained by optimization and has a minimum error with respect to an actual parameter, with the error being less than a set value, as a model parameter of the i-th impedance model; and obtaining an equivalent impedance model for replacing a passive device based on the model parameters of the impedance models respectively corresponding to the M resonant wavebands. Therefore, accurate expression of the impedance of the passive device can be realized, thereby facilitating an electromagnetic-interference suppression design based on an equivalent impedance model.