Permanent-Magnet Machine Field Evaluation With Saturation Iteration
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Solution Overview
Problem
Existing methods for evaluating the electromagnetic performance of permanent magnet machines are limited by long design cycles due to slow computation times and inaccuracies in predicting magnetic field distributions, particularly in considering core saturation and nonlinearity, which hinders optimization and real-world accuracy.
Innovation Solution
A method that divides the electromagnetic analytical model into sub-domains (permanent magnet, air gap, and stator slot) using Poisson or Laplace equations, with equivalent current sheets to represent boundary conditions, iteratively solving magnetic field distributions and current densities to achieve convergent results, thereby accurately calculating electromagnetic performance parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If numerical models are used to accurately calculate core saturation effect, then calculation accuracy is improved, but solving time becomes too long resulting in long design cycle
Solution Approach 1:
The patent segments the electromagnetic field calculation into multiple sub-domains (stator, rotor, air gap, permanent magnet regions), each governed by specific differential equations. This segmentation allows the complex numerical model to be decomposed into manageable parts that can be solved more efficiently while maintaining accuracy in capturing core saturation effects.
Solution Approach 2:
The patent applies different mathematical models and boundary conditions to different spatial regions (sub-domains) based on their local electromagnetic characteristics. For example, the stator and rotor regions use different permeability values and boundary conditions compared to the air gap, allowing accurate local saturation calculation without requiring excessive computational resources across the entire domain.
2Productivity
If analytical method is used to solve linear models with infinite permeability assumption, then solving speed is fast, but error increases as machine saturation increases
Solution Approach 1:
The patent changes the permeability parameter from the infinite permeability assumption in traditional analytical methods to finite, region-specific permeability values that account for saturation. The stator and rotor regions are assigned different permeability values based on their magnetic material properties and saturation states, allowing the analytical method to maintain speed while improving accuracy.
Solution Approach 2:
The patent introduces dynamic boundary conditions and iterative solving procedures that allow the magnetic field distribution to be updated based on saturation levels. The boundary conditions between sub-domains are dynamically adjusted according to the calculated magnetic flux densities, enabling the model to adapt to saturation effects while maintaining analytical solution speed.
Data Source
AI summary
Method for evaluating electromagnetic performance of a permanent-magnet machine, wherein the method is implemented in a computer processer or in a controller of a permanent-magnet machine, calculating the magnetic field distribution by a sub-domain method; using current density of the equivalent current sheet to represent the boundary condition, iterating by the sub-do-main method and by the magnetic circuit method until a convergent result is obtained, calculating the electro-magnetic performance parameters on basis of the convergent result, so as to evaluate the electromagnetic performance.