A Class of Fast Dynamics V/f Sensorless AC General Drives with PM-RSM as a Case Study

Field oriented (FOC) and direct torque and flux (DTFC) control of AC drives are credited with fast torque response, but, in general purpose sensorless AC drives, the on-line software and hardware control effort and their reliability may seem prohibitive for general applications or, at least for synchronous motors, a starting strategy is necessary. The present paper presents a novel class of V/f sensorless AC general drives with two stabilizing loops one based on active flux balance and one based on speed error that provide fast speed dynamics response without steady state error, without speed or current regulators; flux weakening conditions are built in. The exposition of principles is followed by exemplification for IMs, SPMSM, IPMSM, and DC excited SMs and by digital simulations on a PM-RSM (with weak PMs and reasonably high magnetic saliency L-d/L-q>3). Rather promising fast dynamics performance is obtained, in digital simulations for a PM-RSM case study, but more theoretical and then experimental work (which is under way) are needed to fully establish the proposed solutions as practical.