New Stationary Frame Control Scheme for Three Phase PWM Rectifiers under Unbalanced Voltage Dips Conditions

A new stationary frame control scheme for three-phase pulse width modulation (PWM) rectifiers operating under unbalanced voltage dips conditions is proposed in this paper. The proposed control scheme regulates the instantaneous active power at the converter poles to minimize the harmonics of the input currents and the output voltage. The paper novelty is the development of a new current-reference calculation implemented directly in stationary reference frame. This allows using proportional - sinusoidal signal integrators (P-SSI) controllers for simultaneous compensation of both positive and negative current sequence components. No phase locked loop (PLL) strategies and coordinate transformations are needed. A comparison with two other existing control techniques is also performed. Experimental results are presented for a 20 kVA AC/DC converter prototype to demonstrate the effectiveness of the proposed control scheme. Fast dynamic performance with small DC-link voltage ripple and input sinusoidal currents are obtained with this control scheme even under severe voltage dips operating conditions.