CONSTANT GRID CURRENT CONTROL OF

Abstract

Variable frequency drives running loads at constant power increase the current drawn from the grid when the voltage sags. This undesirable increase in current stresses the grid. Linear control theory is applied to a model of a Variable Frequency Drive running an induction machine fan load and a controller is developed which has the drive draw constant current from the grid during voltage sags. The control is implemented in hardware using two GE Induction Machines and Danfoss FC-302 Variable Frequency Drives. Results are presented along with ideas for future work.