Current constraints of PWM rectifier under unbalanced voltage supply

Non-standard conditions in the power network such as voltage unbalance negatively affect operation of electric drives. The unbalance can be caused by a failure in the network or by an unbalanced load in the vicinity of the affected drive. Unsymmetrical voltages at the input of a voltage source inverter cause pulsations in the DC-link voltage when not properly taken care of. This may result in a significant reduction of power capabilities and, therefore, limited controllability of the drive. The paper deals with the analysis of the constraints caused especially by the current stress of the converter´s parts when operated from an unbalanced voltage supply. The influence of circuit parameters on the operating regions and their constraints are particularly dealt with.