Operation of Adjustable Speed Drives under Non Standard Supply Conditions

The demands on the robustness and reliability of electrical drives have been steadily rising during the last decade. In some applications, the users require the drive to continue in operation even under certain non-standard conditions. The discusses various types of non-standard conditions and analyzes what impact these non-standard conditions have on the voltage- source inverter and what countermeasures can be taken in order to minimize their negative impacts on operation of the drive. Special attention is paid to the voltage-source unbalances and control methods eliminating these unbalances are discussed.