Hybrid Computer Simulation of a Controlled-Current Inverter Under Normal and Fault Conditions

Both normal and failure modes of the three-phase bridge autosequentially commutated controlled-current inverter with a counter-electromotive force (EMF) inductive load have been studied by hybrid computer simulation. The four-quadrant normal behavior is similar to a single-phase version of the circuit. In both cases, regions of operation exist that would cause problems with ordinary methods of control. Various modes of failure were simulated for operating conditions typical of an induction motor drive. The most severe type of fault was found to be an open-circuited phase of the load such as may occur in a slip-ring motor drive when the brushes bounce.