A new low-frequency state model of a three-phase three-switch three-level fixed-frequency PWM rectifier

This paper presents a new dynamic model of a three-phase, three-switch, three-level, fixed-frequency pulse-width-modulated (PWM) rectifier. The modeling approach uses the state-space averaging technique in continuous current mode. The averaging process is applied on two time intervals: the switching period for average current evaluation; and the mains period for average voltage computation. A basic mathematical model of the converter is first established. A simplified time-invariant model is then deduced using rotating Park transformation. The steady-state regime is analyzed on the basis of the obtained model, and converter design criteria are consequently discussed. Numerical simulations are carried out in order to demonstrate the effectiveness of the proposed modeling approach.