I-f starting and active flux based sensorless vector control of reluctance synchronous motors, with experiments

This paper presents a novel, hybrid, motion sensorless control of an axially laminated anisotropic (ALA) reluctance synchronous machine (RSM). By separately controlling Id and Iq currents with the reference currents Id*, Iq* being held constant, and ramping the reference frequency, the motor starts with a robust start-up method called I-f control. This kind of control strategy also allows the motor to experience low speeds without initial position estimation or machine parameters identification. The control uses first order lag compensators to ensure smooth transitions from I-f control to active flux based sensorless vector control and vice versa when the frequency reaches a certain level. The control also integrates a state observer based on the active "flux concept" used to deliver RSM rotor position and speed information. Experimental results validate the proposed control strategies.