Design of InterCell Transformers

Parallel multicell converters (often referred to as interleaved converters) allow reducing the total current ripple by summing n phase-shifted phase current ripples. InterCell Transformers are special magnetic devices allowing to obtain the ripple reduction in each phase. To obtain this result, they combine two main functions:
Because of this inherent hybrid nature, their design is different from both the design of an inductor and the design of a transformer, so that a specific design method needs to be established for such devices. The main difficulties of this design is that parameters that are generally of lesser importance are key parameters for ICT: For all these reasons, specific design methods need to be developed for the design of ICTs. An example of such a design tool using constrained optimization routines is described here.

Main Design Interface

Graphic User Interface for ICT Design using constrained optimization routines

Refinement of conductor losses using FEMM

Automatic connection to 2-D finite element software to check inductances and resistances at the different relevant frequencies and obtain a better evaluation of the conductor losses

Refinement of Core losses using iGSE (improved General Steinmetz Equations)

Determination of real flux waveforms in the different core legs and evaluation of core losses with iGSE to account for non-sinusoidal waveforms

Refined optimization

The simplified conductor and core loss models used in the analytic model are tuned to match FEMM and BvsT results; a second optimization is run with this refined model.

Optimisation with parameter sweep

This automatic desgn can be processed for different sets of parameters, which can especially be usefull to evaluate the influence of some discrete parameters: core material, for example, but even more important, the orientation of the winding (vertical | horizontal), or the type of ICT (Cyclic cascade | monolithic | linear), etc.

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  • We would like to make these routines available and we are looking for a volunteer to make this matlab model available on-line. Please contact us !

  • We can also run this model for you to match your specifications. Please contact us !

  • References