Implementation of three-phase frequency converters based on PWM AC matrix-reactance chopper with buck-boost topology

This paper deals with three-phase direct matrix-reactance frequency converters (MRFC) based on unipolar PWM AC matrix-reactance choppers (MRC). 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. This paper presents a design and implementation of two of nine solutions of the MRFC which based on MRC with buck-boost topology. In proposed realizations 9 bipolar and bidirectional IGBT switches plus 3 bipolar and unidirectional IGBT switches are used. A simple low frequency transfer matrix control strategy (modified classical Venturini control strategy) is applied to control of the voltage or current source MC. The modification depends on MC switching during time interval, which is a part of the sequence period. The for step current-direction-based commutation strategy is also used. The specialized DSP and FPGA cards are used in the control circuit realization. Experimental test results of ca 1 kVA laboratory model are presented to confirm the viability of the proposed MRFC solutions.