AC/DC converters with open-end grid for AC machine conversion systems

This paper presents five configurations of AC/DC converters for AC machine conversion systems. They interconnect a three-phase open-end winding grid supplier with DC/AC converters and an AC machine. These configurations are divided into two groups. Group A is composed of configurations with two DC-links, and Group B has configurations with only one DC-link. The discussion is focused on the AC/DC converters of the grid-side, since the arrangements for the machine-side are standard in each case. Group A contains two configurations, and the machine-side is composed of a six-phase AC machine with two conventional three-phase DC/AC converters. Group B has three configurations, and the machine-side can be composed of a six-phase AC machine with one six-phase DC/AC converter or of a three-phase AC machine with one three-phase DC/AC converter. The proposed configurations are employed to reduce the harmonic currents of the grid-side or the switching frequency of the converters. They also guarantee feasibility when highpower applications are considered. Therefore, the analyses of the systems are presented, including the PWM technique and the control strategy. Simulation and experimental results are also presented and compared.