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CHAPTER 1: INTRODUCTION
the filters individually, and the parametrization is described with the guideline they
have been using for the selection of the resonance frequency and the value of the com-
ponents. There is also a description of the key role the parasitic components play at
high frequency, hindering a good attenuation. Their proposed circuit is shown in Fig.
1.12, however there is no indication on which materials have been used for the induc-
tors, nor is there an indication on how the filter has been realized or its dimensions.
In addition the standard they are referring to is the CISPR-11[23], that has different
requirements respect to the case of an airspace related application. Therefore the indi-
cations they provide can be used only for a general idea, they are not sufficient for an
extensive study needed for this thesis.
1.6 Existing HF models
A good approach for a proper filter design implies first an accurate HF modelling and
simulation for the whole system, to perform an initial decision on the filter required and
afterwards an initial tuning of it, without the need of any practical work that is time
and resource consuming. For this application, the HF parametrization started focus-
ing on the motor, that is the device to be controlled. In the scientific literature various
HF models for AC Induction Motors are present, with a range of analytical approaches
[24, 25] and more practical approaches, as in [26], where a model has been developed
(Fig. 1.13a) and then tuned to match existing measurements. Different models with
more detailed information and guidelines for the tuning are provided in [4, 27, 28]. In
particular this last model provides good accuracy in a wide frequency range. It consists
of two coil-like networks in series to represent the part of the winding embedded in
the stator’s slots and the end windings respectively, together with the mutual coupling
(Fig. 1.13b). To tune the model parameters values, a trial and error method has been
used by the authors. The models in [26] and in [4] have been chosen as a starting point
for the HF motor modelling; however, using this model, the matching of the experi-
mental impedance measurements of the motor under test was not satisfying, despite
the large number of attempts tried with the GA algorithms. Hence further investiga-
tion was necessary to find a suitable HF model for the motor of the experimental setup.
Together with the motor HF model, cables and converter need a model too. For the
cables the model will be created as in [29], starting from its geometrical dimensions.
Regarding the converter model, no literature has so far appeared on HF modelling of
Matrix converter, showing therefore the need of investigations in this direction. The
converter model will be here derived starting from the impedance measurements too;
since its power side consists only of IGBTs, its main characteristic is expected to be
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