Direct Power Control of a Three-Phase Rectifier Based on Positive Sequence Detection

This paper presents a model-based controller for the direct control of real and reactive powers in a three-phase three-wire rectifier. As the unbalanced operation is considered, it is convenient to express the grid voltage in terms of both positive and negative sequences, in order to obtain a more complete description of the system. In particular, the positive sequence of the grid voltage is used as the transformation basis to reconstruct the average, i.e., a particular subset, of the conventional power definition. Based on this transformation, the regulation of the average of both real and reactive powers is possible without deformation of the grid current. The proposed controller also incorporates an adaptation mechanism to cope with parameter uncertainties. For comparison purposes, a conventional controller based on the complete definition of the instantaneous powers is also presented. Experimental results are provided to assess the performance of the proposed positive-sequence-based solution and compared with those obtained using a conventional controller.