A simple current regulator for flux-weakened operation of high performance synchronous reluctance drives

High anisotropy synchronous reluctance machines are becoming a practical and cheap choice for high performance drives, but simple control solutions are still investigated because of control sensitivity to anisotropy ratio. Torque sensitivity is discussed with respect to model errors due to iron loss and saturation. A control strategy is derived, based on simple three-phase current regulation with feed-forward EMF compensation. The lack of control at voltage saturation, usually related to this choice, is reinvestigated by means of stability analysis, defining the inverter´s model up to six-step operation. A novel voltage phase-leading method is then proposed and analysed. Analytical design relationships are derived and implemented in a prototype drive adopting a high anisotropy motor. Experimental results verify analytically predicted flux-weakened performances, up to quasi-six-step operation. Interesting drive behaviour is also shown in the constant-torque speed range