A multilevel AC-AC conversion system and control method using Y-connected H-bridge circuits and bidirectional switches

This paper presents a multilevel AC-AC converter using H-bridge circuits and bidirectional switches as the topology of modular matrix converter (MMxC). An MMxC has been proposed for high voltage AC-AC conversion systems without a transformer to convert from an input AC to output AC with an arbitrarily voltage and frequency. We proposed a new bidirectional-switch capacitor-clamped MMxC. The multilevel AC-AC converter consists of two H-bridge circuits on the input/rectifier side and output/inverter side per phase. In addition, capacitors between the H-bridge circuits are connected with bidirectional switches and commutation diodes to control the voltage of capacitors in both H-bridge circuits. The validity of the proposed control scheme of input current, output voltage, and capacitors voltage of the proposed circuit are confirmed with simulation study. Furthermore, it is shown in this paper that the number of voltage steps and the number of devices are increased and decreased, respectively, than those of the conventional MMxC by adding auxiliary H-bridge circuits with floating capacitors to the proposed topology.