Two methods for controlling three-time fundamental frequency neutral-point voltage oscillation in a hybrid VIENNA rectifier

摘要

This study presents two methods of controlling neutral-point voltage oscillation in a hybrid VIENNA rectifier, which is composed of the parallel association of a three-phase single-switch Boost rectifier with a VIENNA-type rectifier. The neutral-point oscillation reason has been analysed with a mathematical model. Meanwhile, the two neutral-point control methods of a simplified method based on a zero-sequence component injection and a dual-carrier pulse-width modulation (PWM) method are proposed to control the voltage deviation of the split DC-link and three-time fundamental frequency neutral-point voltage fluctuation with a decrease from +/- 1.6 to +/- 1V, respectively. Moreover, the significant oscillation in the neutral-point voltage caused by unbalanced loads or asymmetric capacitor parameters can also be effectively suppressed by using the dual-carrier PWM method. Furthermore, the performance comparison between these two methods is provided. The experimental results show that the system after being introduced the proposed two methods still exhibits a low-order input current harmonic such as second, third, and fourth harmonics as well as the input current total harmonic distortion is lower than the standard 5%.