Improved output power capability of Hybrid Excited Flux-Switching DC-Alternators: Analysis and experiments

In this paper, performance evaluation of a Hybrid Excited Flux-Switching Permanent Magnet (HEFSPM) DC-generator is presented. The application principle of a DC controlled bus over a wide speed range will be firstly detailed. The main idea of such machine topology is that all the active parts are located in the stator so that the air-gap flux can be easily controlled with no need of brushes. This scheme uses a low-cost diode bridge rectifier directly connected to the HEFSPM Generator to transfer active power to the battery and the load. By means of Finite Element Analysis (FEA), a simple methodology was developed to determine the power capability of the proposed structure. The influence of the BH magnetization curve will be also explored. Experimental results on a 3kW - 24-Slot 20-Pole HEFSPM DC Generator were performed and compared to the previous analysis. This relative low time-consuming approach could be useful to predict, with good agreement, the power capability of hybrid excited generator. Finally, an original compensation technique to improve performance of the generator is discussed. An analytical approach to predict the impact of series capacitor on the power capability is proposed and then validated by experiments. It is demonstrated that low speed power capability can be enhanced by 2.5 times using this technique.