Modelling of voltage transfer function of the three-phase hybrid transformers with voltage or current source matrix converter

This paper deals with a three-phase power system with hybrid transformer (HT). The HT contains a conventional three-phase transformer with electromagnetic coupling and AC/AC converter integrated with the secondary windings through an electric coupling. The HT uses a three-phase Yy connected transformer with additional secondary windings and three-phase voltage or current source matrix converter (VSMC or CSMC), which give possibility to changing the value and phase shifting of the output phase voltage. The paper gives a description of such power system with passive load, as well as the modelling and comparison of voltage transfer functions for both solutions of the HT. The steady state analysis results of power systems with simplified HT models are verified by means of the simulation and experimental test results obtained for the power system with HT of about 6 kVA.