Swiss rectifier output voltage control with inner loop power flow programming (PFP)

A novel control scheme is proposed for a three-phase buck-type SWISS rectifier. This control is based on an inner loop power flow programming that provides a well damped behavior of the output filter and decoupled input filter and converter dynamics. A DC/DC equivalent circuit of the SWISS rectifier is used for the analysis and evaluation of different control concepts for the switching stage of the converter. By using different feedforward loops for the calculation of the duty cycles the behavior of the converter can be modified to suit a desired characteristic. In this way, the converter can be programmed for constant voltage transfer ratio, constant output voltage, constant power transfer or other input/output relations. A comparative evaluation of different inner loop control schemes is presented. The control schemes are compared analytically using small-signal linear models. The comparison considers the dynamic behavior as well as the decoupling of the input and output variables. Simulation results using the DC/DC equivalent circuit model and the actual three-phase SWISS rectifier are presented. According to the results, the PFP control achieves an improved behavior of the converter in terms of damping of the resonances and decoupling of the input and output variables, compared to the other control schemes.