“Active Flux” DTFC-SVM Sensorless Control of IPMSM

This paper proposes an implementation of a motion-sensorless control system in wide speed range based on "active flux" observer, and direct torque and flux control with space vector modulation (DTFC-SVM) for the interior permanent magnet synchronous motor (IPMSM), without signal injection. The concept of "active flux" (or "torque producing flux") turns all the rotor salient-pole ac machines into fully nonsalient-pole ones. A new function for L_q inductance depending on torque is introduced to model the magnetic saturation. Notable simplification in the rotor position and speed estimation is obtained, because the active flux position is identical with the rotor position. Extensive experimental results are presented to verify the principles and to demonstrate the effectiveness of the proposed sensorless control system. With the active flux observer, the IPMSM drive system operates from very low speed of 2 r/min at half full-load up to 1400 r/min. Higher speed is possible, in principle, with flux weakening.