A Comparison of Two Controller Designs for a Hybrid Excitation Synchronous Generator for Wind Applications

The purpose of this paper is to establish a robust and low-cost structure for a generator connected to an isolated load for wind applications. In a hybrid excitation synchronous generator (HESG), the excitation flux is created by both permanent magnets and excitation coils, so the output voltage can be controlled by the DC excitation field. For isolated loads, it is then possible to use a simple and very reliable wind generator architecture, composed only by a HESG, a rectifier and a DC/DC converter to control the excitation flux. However, HESM are non-linear machines so, regarding their control, conventional controllers are not always sufficient to ensure a good stability and high performance. In this paper, a comparison between a PI controller and an H∞ controller is investigated. The comparison examines both performance and robustness to parameters’ uncertainty.