MODELLING AND CONTROLLING OF SURFACE MOUNTED PM MOTORS INCLUDING SATURATION EFFECTS

The high speed range control techniques of permanent magnet surface mounted (PMSM) ac machines, generally need an accurate determination of machine parameters at the designing stage of the control hardware and software. In fact, wrong values of some machine parameters can heavily effect the drive performances. Generally, PMSM ac machine are analysed by using a non salient model. This hypothesis is correct if it is possible to neglect the iron saturation due the rotor field. But when high field magnets are mounted on the rotor surface, different saturation conditions could occur in the stator iron along dand q- axis, and therefore a salient model has to be considered for a correct modelling of the PMSM machine. Particularly, different values of d- and q- axes inductances can be taken into account. The above phenomenon, if not considered, could introduce errors in terms of torque and current tracking especially if a high speed range is required. A self-commissioning algorithm is presented in the paper, which allows the determination of the parameters of saturated PMSM machine fed by a VSI. The proposed algorithm can be easily implemented and can be split in a start-up routine and an on-line procedure. In this way, a precise and quick evaluation of the motor parameters can be achieved, as shown by the experimental results.