V/f with Stabilizing Loops and MTPA versus Sensorless FOC for PMSM Drives.

In this article, a V/f control with two stabilizing loops and maximum torque per ampere (MTPA) control for spoke-PM synchronous motor drives is proposed, and experimentally compared against a sensorless field-oriented control (FOC) strategy based on active flux observer. To improve the drive dynamics, the standard V/f control is enhanced with two stabilizing loops, which provide corrections for stator voltage vector amplitude and phase. The novel voltage amplitude correction is based on MTPA method employing the magnetic energy and active flux concepts. The voltage angle correction employs the active power variation and works only in transient operations, to preserve the synchronism. The sensorless FOC, used for comparison, is based on an active flux observer which uses a PI compensator with the active flux error correction between the voltage and current models. Extensive comparative experimental results in sensorless large speed range, minimum speed being 100 rpm (0.022 p.u.), with speed reversal and quick load torque, validate the two control systems. Good close performances are obtained, FOC being more stable and less influenced by parameter variations. [ABSTRACT FROM AUTHOR]