A simplified averaged dynamic model of a permanent magnet synchronous motor driven by a two-level, three-phase, self controlled transistorized voltage source inverter under 120° conduction mode

This paper proposes an averaged dynamic model of a permanent magnet synchronous motor (PMSM) exhibiting sinusoidal flux distribution, while fed from a two-level voltage source inverter (VSI), operating in 120deg conduction mode. This averaged model is formulated in the light of a conventional permanent magnet DC motor with mechanical commutator and is found similar. A "Detailed Numerical Model", which is totally numerical in nature and which more accurately models the inverter device switchings of 120deg conduction mode, is initially developed. The results, predicted by this model are first validated against experiments done on a laboratory prototype PMSM, developed in recent past, which nearly exhibits a sinusoidal back EMF distribution. They are found to match closely. Thereafter, the results predicted by the proposed averaged dynamic model are compared against those predicted by the 'Detailed Numerical Model' under identical operating conditions. The results are found to be close and are presented.