Detection and optimal compensation of unbalanced AC motor drives using DISC analysis

This paper develops a new feedback control method for fault detection and real-time compensation of unbalanced three-phase motor drive systems. This method is based on an extension time-domain symmetrical component theory where a new transformation is used to express the sequence components in state-space form. This transformation relies upon a decomposition of the instantaneous sequence components (DISC transformation). Unlike previous analysis techniques, this method models the dynamics of positive and negative sequence components for systems with arbitrary resistance, inductance, and capacitance imbalances in a systematic manner. Dynamic models derived using the DISC transformation are well suited for real-time compensation and fault detection in three-phase motor drives. This paper develops the theory of the DISC transformation and gives an application to the optimal compensation of a permanent magnet synchronous motor drive with a resistance imbalance. Experimental measurements from a laboratory inverter are provided to confirm the theoretical development.