Three-Phase AC-AC X-type Indirect Matrix Converters with Open-end Rectifier Stage

A Three-Phase AC-AC X-type Indirect Matrix Converter (XIMC) without using any intermediate energy storage is proposed, which is implemented by eighteen transistors and diodes. The XIMC results in a simple power circuit, and it has a low complexity commutation scheme. A new modulation scheme with a unity voltage transfer ratio is proposed in this paper, which is titled high voltage modulation scheme. The XIMC is suitable for a low-power energy conversion system. The XIMC is a unidirectional converter, and it has a phase displacement at the input, and at the output limited to $\pm \pi/6$. However, the bidirectional power flow can be achieved by adding a voltage and/or current inverting switching section. The open-end terminals of the rectifier stage provide a high level of freedom for the generation of the DC-link voltage resulting in three operation modes, which produce near sinusoidal output currents with THD below 5% for all of them. The XIMC is verified by simulation, and the generation of the DC-link voltage is proved by simulation and experimentally using the X-type current source converter prototype.