Control under normal and fault operation of a PM synchronous motor with physically and magnetically decoupled phases

Thanks to their particular design, HDD servomotorsreg are a family of PM synchronous motors which offer, in addition to their higher torque to mass ratio, very interesting features for high reliability drives. Indeed, in these motors the phases are physically and magnetically decoupled so that an internal fault in one phase or the loss of feeding of one phase has no influence on the other ones. The aim of this paper is to describe a control strategy for this type of motors. The research reported in this paper was performed within the European Union FP6 project DRESS (Distributed and Redundant Electromechanical nose gear Steering System) for more electrical aircraft.