Optimal Current Distribution in Multi-Winding Transformers

Introduction

This repository contains an implementation of the optimal current sharing in multi-port / multi-winding transformers. From the impedance matrix, the optimal currents (amplitudes and phases) are computed in order to minimize the losses.

A full description of the optimal operation of multi-port / multi-winding transformers can be found in:

• Optimal Current Distribution in Multi-Winding Transformers for Isolated and Wireless Power Transfer
• K. Datta, Y. Wu, C. R. Sullivan, and J. T. Stauth
• https://doi.org/10.1109/OJPEL.2025.3590020
• IEEE OJPEL 2025

Two different optimization methods are available:

• Eigenvalue method (neglect the mutual resistances, described in the paper)
• Numerical solver (include the mutual resistances, not part of the paper)

The numerical solver features several advantages compared to the eigenvalue method:

• Usage of a standard quadratically constrained quadratic solver.
• Analytical expression for the gradient vectors and hessian matrices.
• Complex objective function including the reactive power.
• Inclusion of the mutual resistance coefficients.

Main Files

• run_single.m - Solve the optimal current sharing problem for a multi-winding transformer
• run_sweep.m - Optimal current sharing with loss and reactive power minimization
• get_problem.m - Definition of the transformer and the power flow
• get_tolerance.m - Definition of the numerical tolerances

Compatibility

• Tested with MATLAB R2024b.
• The gads_toolbox is required.
• The optimization_toolbox is required.

Author

• Thomas Guillod
• Email: guillod@otvam.ch
• Website: https://otvam.ch

Credits

This code was created at Dartmouth College by the research group of Prof. Sullivan:

• Dartmouth College, NH, USA: https://dartmouth.edu
• Dartmouth Engineering: https://engineering.dartmouth.edu
• PMIC: https://pmic.engineering.dartmouth.edu

License

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