Abstract
This paper proposes two new “disturbance-observers in the D-module" for sensorless drive of synchronous motors including permanent-magnet synchronous motors and synchronous reluctance motors. The disturbance filter for the observers can estimate speed-varying rotor-phase (in other words, rotor-position) with zero phase-lag. It is constructed by means of “the filter in the D-module", which has the following desired characteristics for variable sensorless drive: 1) it makes distinction between positive and negative frequencies of two-phase signals; 2) it can allow to process the signals based on frequency polarities; 3) it can also change dynamically its center frequency of band-pass filtering according to rotor speed estimates; 4) its passband and transition can be designed independently; and 5) it can be easily realized. The new disturbance-observers also have a generality such that they contain the recently proposed disturbance-observer as a special case.
