Phase-Shift-Free Current Reconstruction Strategy for Flux Modulated Doubly-Salient Reluctance Motor Drives With Central-Symmetric Modulation

A novel phase current reconstruction method is present in this paper for the flux modulated doubly-salient reluctance motor drive without phase shift. Conventionally, each phase current must be sampled individually with different sensors as the zero-sequence current (ZSC) excitation is required, which significantly increases the system cost. Besides, to achieve the ZSC excitation, the switching sequence of the converter is much more complicated, where conventional phase current reconstruction strategies cannot be utilized. For switching sequence simplification, the active-vector-based zero sequence voltage (ZSV) modulation is utilized. In addition, the current sensor installation position and corresponding sampling method are put forward to reconstruct phase currents considering ZSC detection. Furthermore, a central-symmetric duration time extension method is presented to avoid sampling failure in immeasurable regions, where complicated switching signal phase-shift calculation can be avoided. Moreover, the influences of the immeasurable region compensation algorithm on the switching sequence and the common-mode voltage distribution are also investigated. With the proposed scheme, accurate reconstruction of three-phase currents can be obtained by utilizing one current sensor. Experimental validations are put forward with a prototype to evaluate the performance of the proposed scheme.