Six-Phase Machine Conversion System With Three- and Single-Phase Series Converters

This paper presents two conversion systems based on the association of a six-phase machine (SPM) with an electrical grid by means of three- and single-phase converters. The machine is composed of two three-phase groups. One of them provides the power to the three-phase converter, and the other provides the power to the single-phase converters, in an open-end winding connection (see Fig. 2). The first conversion system is composed of bidirectional switches and can be used with induction or permanent-magnet synchronous machines. The second system is partially reversible since the single-phase converters are also composed of diodes and is more indicated for permanent-magnet synchronous machines. Furthermore, the proposed configurations do not use transformers and generate multilevel voltage at the grid-side converter with amplitude higher than that of the machine side, permitting one to reduce the transmission I²R losses. The complete analysis of the systems, including the pulsewidth- modulated techniques, is presented. Simulation and experimental results are also presented.