Analysis of Direct Flux Observation for field oriented control PMSM

Abstract:
This paper addresses the problem of measuring and analyzing the inductance variation depending on the rotor position of a star connected permanent magnet brushless motor at the aim to provide the sensory information necessary to control the motor. A new technique is presented which allows to calculate the electrical rotor position without speed limits and including standstill conditions. At this aim a modified PWM pattern is used which excites the motor phases so that only the star point voltage must be measured in order to track inductance variations. This technique has been implemented and tested on a low quality PMSM. Finally, this technique has been compared to a measured rotor position by incremental encoder technique.