Control of active front-end rectifier under unbalanced voltage supply and DC-link pulsations

Voltage pulsations in the DC bus may develop if the voltage-source inverter is fed from an unbalanced voltage supply. Negative effects on the connected electric machine and on the power grid usually result from such operation. It is possible to entirely eliminate or at least minimize such negative effects by suitable control of the active front end of the inverter. The control range of the active front end rectifier is reduced in such a mode of operation. Suitable control method for eliminating the voltage pulsations in the DC bus is discussed in the paper and operation in case of various types of unbalance is simulated and investigated.