Magnetic Circuit Vector Model for High-Frequency Eddy Current Loss
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Solution Overview
Problem
Current methods for calculating eddy current loss in magnetic materials are inaccurate due to the nonlinear nature of silicon steel and the constant eddy current loss coefficient, leading to errors in high-frequency applications, especially when the frequency increases, affecting the performance of high-frequency electrical equipment.
Innovation Solution
A vector model of a magnetic circuit is proposed, where eddy current loss is equivalent to a lumped parameter magnetic-inductance component, allowing for the calculation of eddy current loss using a vector model {dot over (F)}={dot over (Φ)}·(Rmc+jωLmc), where j is the imaginary unit, Rmc is reluctance, ω is angular frequency, {dot over (Φ)} is magnetic flux, and {dot over (F)} is magnetomotive force, enabling fast and accurate estimation by deriving magnetic-inductance and virtual magnetic power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the model of separating the iron loss is used to calculate eddy current loss, then the calculation can be performed, but the nonlinear feature of silicon steel sheet is not fully considered, leading to error in calculated iron loss
Solution Approach 1:
The patent introduces a frequency-dependent eddy current loss coefficient that changes with frequency according to the formula k2 = k2_0 / (1 + α*f), where α is a material parameter. This parameter change allows the model to account for the skin effect and nonlinear characteristics of silicon steel at different frequencies, thereby improving calculation accuracy without significantly increasing computational complexity.
2Reliability
If ANSYS Maxwell dynamic calculation method is used, then the iron loss can be calculated dynamically with time-stepping finite element, but a constant eddy current loss coefficient is adopted, leading to error in eddy current loss at different frequencies
Solution Approach 1:
The patent modifies the constant eddy current loss coefficient used in ANSYS Maxwell by introducing a frequency-dependent expression k2 = k2_0 / (1 + α*f). This allows the dynamic time-stepping finite element method to accurately capture the variation of eddy current loss with frequency, resolving the contradiction between dynamic calculation capability and frequency-dependent accuracy.
3Measurement precision
If the one-dimensional finite element method is used to directly solve the distribution of eddy current field, then the eddy current loss can be calculated, but the calculation load is relatively large
Solution Approach 1:
The patent extracts the eddy current loss calculation from the full-field finite element analysis by introducing an equivalent magnetic-inductance component in the magnetic circuit model. This extraction allows eddy current loss to be calculated using the simpler magnetic circuit equations P = ω²Lmc|Φ|², significantly reducing calculation load while maintaining accuracy for high-frequency applications where eddy current loss dominates.
Solution Approach 2:
The patent introduces a dynamic eddy current loss coefficient that varies with frequency, allowing the magnetic circuit model to adapt to different operating conditions. This dynamic parameter adjustment enables accurate eddy current loss calculation across a wide frequency range without requiring complex full-field finite element analysis at each frequency point.
4Measurement precision
If finite element method is used to calculate magnetic field distribution first and then calculate loss through post-processing, then the loss can be obtained, but the calculation load is relatively large
Solution Approach 1:
The patent extracts the eddy current loss calculation from the post-processing stage by introducing an equivalent magnetic-inductance component in the magnetic circuit model. This allows eddy current loss to be calculated directly during the magnetic field analysis using the simplified equation P = ω²Lmc|Φ|², eliminating the need for separate post-processing and significantly improving calculation efficiency.
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 method improves the accuracy of magnetic field distribution calculations and reduces the computational load, enabling faster and more precise eddy current loss calculations, enhancing the design efficiency of high-frequency electrical equipment.
Implementation Method 1
an excitation voltage with a frequency of f1 is applied to an excitation coil, generating an excitation current, an induced voltage is induced on a detection coil
Implementation Method 2
an induced voltage is induced on a detection coil
Implementation Method 3
an eddy current reaction is equivalent to a lumped parameter magnetic-inductance
Implementation Method 4
the eddy current loss coefficient decreases as the frequency increases because of the skin effect
Data Source
AI summary
The present invention discloses a calculation method of eddy current loss in magnetic materials based on magnetic-inductance. The present invention proposes a vector model of a magnetic circuit, an eddy current reaction is equivalent to a magnetic-inductance component in the magnetic circuit, and the eddy current loss can be fast calculated by the vector model of the magnetic circuit. When the frequency is high, the eddy current loss dominates an iron loss and can be estimated as an entire iron loss. The present invention proposes the vector model of the magnetic circuit based on which the calculation method of eddy current loss in magnetic materials is proposed as well. Through the proposed method the eddy current loss in magnetic materials can be directly calculated by using the magnetic-inductance and the magnetic flux in the magnetic circuit, which can provide guidance for design and performance evaluation of high-frequency electrical equipment from a brand new viewpoint.