This MATLAB code extracts the resistance/inductance matrix of a system:

• Different operating points are provided (measured or simulated current excitations).
• The associated losses/energies are provided (measured or simulated values).
• The corresponding resistance/inductance matrix is extracted.

The following the quadratic form is linking the aforementionned variables:

• U = 0.5*I_vec'*Q_mat*I_vec
• I_vec is the vector containing the applied currents
• Q_mat is the resistance/inductance matrix
• U is the loss/energy value

This code is handling the following cases:

• n_op is the number of provided operating points
• n_var is the number of independent coefficients for the resistance/inductance matrix
• n_op<n_var: under-determined equation system => invalid problem
• n_op==n_var: determined equation system => linear equation system
• n_op>n_var: over-determined equation system => least-square fit

The condition number of the equation system and the residuum are computed. This is required to ensure that the resistance/inductance matrix is numerically robust. Finally, the code checks that the extracted matrix is physical (symmetric and positive definite).

• Tested with MATLAB R2021a.
• No toolboxes are required.
• Compatibility with GNU Octave not tested but probably easy to achieve.

Thomas Guillod - GitHub Profile

This project is licensed under the BSD License, see LICENSE.md.