Automatic Tuning for Sensorless Commissioning of Synchronous Reluctance Machines Augmented With High-Frequency Voltage Injection

Sensorless control of synchronous reluctance motors (SyRMs) relies on the knowledge of the machine current-to-flux maps. Previous work demonstrated the feasibility of sensorless identification of the flux maps, performed by exciting the machine with square-wave voltage pulses at standstill, and without the need of rotor locking. The rotor position was initially estimated and then used throughout the identification, in open-loop fashion. In some cases, rotor oscillation and eventually position drift led to stop the identification before the programmed dq current domain was covered entirely. In this paper, the rotor position is closed-loop tracked during the motor commissioning to counteract the occurrence of rotor movement. The hysteresis-controlled excitation voltage is augmented with an high-frequency (HF) square-wave voltage component, and the position is tracked through demodulation of the current response to such HF component. The proposed approach is experimentally verified on a 2.2-kW SyRM prototype. The results show that the i
_d
, i
_q
commissioning domain is substantially extended, resulting in more accurate flux maps. Moreover, self-tuning of the method is addressed and possible causes of error are analyzed and commented.