Modelling, improvement and experimental validation of a 50 kHz-5 kVA litz-wired transformer for PV inverters

Modelling of medium-frequency power transformers is analyzed and experimentally validated to characterize these devices along the operating power range. Special attention is paid to the core losses, winding losses and thermal modelling at operating conditions typical of power electronics applications. The performance of a commercial 50 kHz-5 kVA litz-wired transformer for PV resonant converters is characterized and tested by means of a specific measurement procedure. A complete model is selected from the estimated and measured results. Finally, this model is applied to improve the design of the commercial transformer previously analyzed in order to match typical PV requirements such as a high efficiency at different irradiation levels.