A simple predictive control technique of power electronic transformers with high dynamic features

The paper deals with control methodologies of power electronic transformers (PET) which include a single-phase medium-frequency (MF) electromagnetic transformer. Reference is made to a PET configuration having dc-links either in high-voltage or in low-voltage sides. Both primary and secondary windings of the ferrite-core transformer are supplied by a voltage-source-inverter (VSI, on high-voltage side) and by a voltage-source-rectifier (VSR, on low-voltage side) which impose square-wave voltages. The proposed control strategy has the aim to define the optimised delay between primary and secondary voltages which allows us to obtain the power instantaneously demanded by the load, ensuring fast dynamic response and maximization of the power/current ratio. The control algorithm is based on algebraic equations derived from the mathematical model of the considered system by means of proper simplifications. The used predictive technique gives good results also in four quadrants operations. An application to a traction drive is analyzed.