Sensorless Magnetic Model and PM Flux Identification of Synchronous Drives at Standstill

This paper proposes a sensorless self-commissioning technique for PM-assisted synchronous reluctance motors. The identification of the machine’s flux maps is performed at standstill without any position transducer and with no need of rotor locking. The machine is first excited with alternated high voltage pulses, injected in the estimated d and q directions of the rotor to determine its saturation curves. Then, direct current values are applied in a fixed stator direction so that the rotor aligns in specific positions giving information on the PM flux linkage. Experimental results are provided on a PM-assisted synchronous reluctance motor prototype, confirming the validity of the proposed method. The key original feature of the proposed work is the estimation of magnet flux linkage at standstill. For the motor under test, the magnet flux linkage was sensorless estimated at standstill with an error lower than 3%.