Unidirectional Five-Level Rectifiers for WECS Applications

This paper proposes two three-phase five-level power conversion systems. They can be employed in a wind energy converter system (WECS) application as the machine side rectifier, connected to the permanent magnet synchronous machine (PMSM) by an open-end winding (OEW) arrangement. Compared to the conventional topology, proposed ones lack the use of six clamping diodes in their structures. Even though, they also achieve the same power quality as the conventional one. Besides, proposed configurations may have fewer semiconductor devices in the current path, providing slightly lower power losses. Furthermore, the control system used ensures the synchronization between voltage and current, providing a high power factor operation. The converter equations, pulse-width modulation technique, and control strategy are detailed. Simulation and experimental results are provided in order to confirm their performance and feasibility.