Modeling and analysis of a digitally controlled high power switch-mode rectifier

A recently proposed high power switch-mode rectifier topology offers advantages over the conventional line-commutated thyristor rectifiers in terms of size and cost. This paper presents modeling and analysis of the high power switch-mode rectifier configuration, operated under a newly developed digital control strategy. The developed strategy provides a fast transient response to disturbances and achieves equal current sharing between the buck converter modules which are paralleled within the switch-mode rectifier. A continuous-time state-space model of the switch-mode rectifier and analyses of both the steady-state and the transient operation modes of the digitally controlled rectifier are presented. The continuous-time model is used as a basis for time-domain simulations of the rectifier's behavior in the MATLAB/Simulink environment. The validity of the presented model is demonstrated based on comparison between the simulation results and the corresponding experimental results. The experimental results are obtained from a 2-kW scaled-down laboratory setup of the rectifier. The stability of the digitally controlled rectifier system is also examined based on an overall small-signal sampled-data model of the rectifier system including the controls.