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Transformers and Inductors for Electronics Applications


Research Topics



Free Software

Information for Designers



Thayer School of Engineering

Dartmouth College

The LitzOpt Program


Free Matlab program to optimize transformer litz wire strand design by minimizing costs and power losses.


Litz wire is typically used when operating frequencies are high enough to degrade the performance of magnetic components (10 kHz–1 MHz). The main advantage of using litz wire is that it reduces eddy-current losses. LitzOpt offers an array of design alternatives, ranging from more expensive, very low loss-designs to low-cost higher-loss designs. Typically, all of these alternatives vastly decrease costs or losses relative to standard rule-of-thumb designs, and many of them offer improvements in both cost and loss. The algorithm used in LitzOpt is explained in detail in "Optimization of a flyback transformer winding considering two-dimensional field effects, cost and loss." This paper and related papers can be downloaded from here.


LitzOpt can be used to minimize winding loss in transformers with multiple windings, arbitrary waveforms, and two-dimensional or three-dimensional field geometry. Waveforms are entered into LitzOpt as piecewise linear. LitzOpt can optimize a transformer stranding design considering one-dimensional and two-dimensional field effects. Optimization accounting for three-dimensional field effects requires the user to perform a numerical field solution with any third-party finite element or other numerical field solution software. To simulate, the user is to model the entire region of the windings as regions of uniform current density to simplify calculations (see 'Obtaining the Squared Field'). The required magnetostatic field simulation is far more computationally efficient than a full-blown field simulation and all that is to be computed is the spatial integral of squared flux density over the winding cross-sections (considered as regions of uniform current density).

LitzOpt begins with a fixed number of turns, core geometry, and winding configuration and optimizes the number and diameter of strands. LitzOpt assumes that the wire is small compared to a skin depth (d < δ).

What software do I need? Where do I download?

LitzOpt is for use with Matlab Version 5 or 6, available from MathWorks for a variety of platforms. Download LitzOpt here.

For Help or Instructions

For comments or questions e-mail: Charles.R.Sullivan@dartmouth.edu.
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