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