Modeling, control and implementation of the quasi-single stage three-phase zero-voltage zero-current switched buck rectifier

Large signal average model for the quasi-single stage three-phase zero-voltage zero-current switched (ZVZCS) buck rectifier operated with space vector modulation (SVM) is developed. The model reveals strong nonlinear relations between applied and effective duty-cycles, near the 60° electric sector boundaries, which lead to high input current distortion and output voltage ripple inadmissible in telecommunications applications. PLL and look-up table based SVM, and analog filter inductor current and output voltage compensators are implemented to provide both minimum number of sampled variables (maximum sampling frequency and loop bandwidth) and easy introduction of duty-cycle feedforward compensation (equalization) through power series approximation. Results from a 6 kW prototype validate both the large signal model and duty-cycle compensation scheme