Control of a seven-phase axial flux machine designed for fault operation

This paper deals with control in fault operation of a seven-phase Permanent Magnet Synchronous Machine supplied by a seven-leg Voltage Source Inverter (VSI). Using a Multi-Machine description, a seven-phase machine which presents a special ability to be controlled with only five phases supplied has been designed. The machine is presented and experimental results are provided when two phases are opened. In a first case of no change of classical control, high torque ripples are observed. In a second case, a specific control deduced from the Multi-Machine modelling is suggested for reducing torque ripples.