F. Stögerer, J. Miniböck, J.W. Kolar:
"A Novel Control Concept for Reliable Operation of a Three-Phase (VIENNA) Rectifier under Heavily Unbalanced Mains Voltage Conditions.";
Poster: Drives and Control and Power Electronics Conference, London UK; 03-13-2001 - 03-15-2001; in: "Conference Session Proceedings", Session 5 (2001), 39 - 46.

A novel concept for reliable output voltage control and mains voltage proportional guidance of the input currents of a three-phase/switch/level PWM (VIENNA) rectifier system connected to an unbalanced mains is proposed. The system comprises individual ramp comparison phase current controllers where a zero sequence component is added to the mains voltage pre-control signals in a way, that the PWM is equivalent to a space-vector-modulation concerning the input current ripple amplitude and the modulation limit for symmetric mains. By calculating the current reference values for each phase from the output signal of the output voltage controller under consideration of the maximum allowable mains current amplitude and the actual mains phase voltages overloading the system is prevented inherently also in case of two-phase operation. The control concept is analyzed in detail theoretically and verified experimentally in connection with a 6.5kW prototype of the PWM rectifier system.