Performance of three- and five-phase PM-based wind generators under rectifier diode failures

Multi-phase generators have been proposed for use in wind generators. They offer improved torque ripple and system efficiency. It has also been suggested that energy capture is improved during periods when the system has system failures in the power converter. This paper assesses the performance of a small-scale, 900 W, 5-phase system when operated with one and two diode failures in the diode rectifier and focuses on the power output given RMS current limits imposed on each phase winding. This shows that there are wind speeds where there is an advantage over 3-phase counterparts, but there are also regions where the performance is marginally poorer. This is significant as whilst the 5-phase machine offers improvements, there are operational conditions under diode failures where the power output of the 3-phase system is superior, albeit with higher torque ripple.