Machine interactions in field oriented controlled multi-machine three phase induction motor drives

This paper is concerned with the interactions between the induction motors of a single-inverter, two-machine field-oriented drive system. The machine interactions considered here are those through the field oriented controller. The paper considers a multi-machine field-oriented controller that is based on a machine model which is the average of the models of the two machines. Interactions that occur due to load torque differences are described for machines of different ratings. Also considered in detail are machine interactions due to a small stator turns fault in one machine. A faulty machine, when controlled by a field-oriented controller, shows unbalance in currents and voltages. These affect the currents and field-orientation in the parallely connected healthy machine as well. An experimentally validated dynamic model of an induction machine with stator faults is used to analyse these interactions. The paper presents a detailed analysis and experimental results of these machine interactions.