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Phone 33/(0)4.76.82.62.99, Fax 33/(0)4.76.82.63.00,Abstract -A lumped component equivalent circuit has been developed by our team to model the linear electrical behavior of any two winding transformer. Its topology is independent of sizes and technology and a general method of characterization, based exclusively on external impedance measurements, have been presented. Unfortunately, when some key frequencies are out of the range of the measuring apparatus, many of its components remain unevaluated. Owing to a new understanding of magnetic and electrostatic coupling, a several step approach is presented. At each step a more accurate circuit, proven to be effective in electronic simulation, is fully characterized. This method suits whatever the number of windings and experimental data will be presented for two and three winding transformers.

This paper deals with a simplified and meaningful thermal model used to extract the cell temperature of a photovoltaic (PV) module. This model that takes into account the ambient temperature, incident irradiance and wind velocity is calibrated using a complete experimental database. The results of the thermal modeling provide a heat transfer coefficient law that could be implemented into a PV simulation tool. Two key elements of this approach may be highlighted. The results enable to better calculate the solar energy production of a PV module and to predict the energy efficiency of a PV system.

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In high frequency, due to skin and proximity effects, inductance and resistance of wound components become frequency dependant: impedances proportional to the square root of frequency are often encountered. Such a behaviour is tricky to represent accurately by an electrical equivalent circuit.This well-known problem is referenced as "half order system" representation. In this paper, it is shown how to design a circuit, made of constant resistances and inductances, which behaves as the leakage inductor of SMPS transformer. Attention is paid to minimise the component number, necessary to reach a given accuracy and a given frequency range.

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