| Abstract |
This paper deals with three-phase direct matrix-reactance frequency converters (MRFC) based on unipolar PWM AC matrix-reactance choppers (MRC). The topologies of the proposed MRFC are based on a three-phase unipolar MRC structure. Each MRC with conventional topology has two synchronous-connected switches (SCS) sets. In the MRFC, unlike the MRC topology, one of SCS sets is replaced by a matrix-connected switches (MCS) set in order to make possible of the load voltage frequency change. Six new topologies of the MRFC based on MRC boost, buck-boost, Ćuk, Zeta or SEPIC structures are presented. Through the generation concept of the proposed converters both the description of abovementioned converter topologies and general description of the control strategies are presented. The structure of the proposed MRFC contains a three-phase matrix converter (MC), which is introduced instead of the source or load SCS used in unipolar MRC. The step-down or step-up of the MC set is dependent on the input and output voltage or current source configurations. Analysis determining the location where the MC should be introduced is realized by means of the one-cycle switched models with suitable voltage and current sources introduced instead of the capacitors and inductors respectively. Furthermore, exemplary results of the simplified theoretical analysis, based on the averaged state space method, as well as simulation test results obtained for a classical Venturini control strategy of MC, are also presented as an initial verification of the properties of the proposed converters. |
