Improved control scheme for three phase PWM AC/DC converter under unbalanced voltage dips conditions

An improved control scheme for three-phase pulse width modulation (PWM) AC/DC converter under unbalanced-voltage dips operating conditions is proposed in this paper. The proposed control scheme uses Proportional - sinusoidal signal integrators (P-SSI) controllers for simultaneous compensation of both positive and negative current sequence components, with a new current-reference calculation in stationary reference frame. As consequence, phase locked loop (PLL) schemes are not required. This control scheme achieves good dynamic performance with ripple free dc link voltage and input sinusoidal currents under voltage dips operating conditions. The effectiveness of the proposed control scheme is demonstrated through simulation results.