DC load unbalance and mains disturbances effects on a three-phase three-switch three-level boost rectifier

In this paper, abnormal operating conditions impacts on a three-phase three-switch three-level boost rectifier are presented and analyzed. A state-space low frequency model of the converter is presented. The main considered disturbances are firstly a load unbalance on the DC side, and secondly a short-time increase or drops of the AC supply voltage. The mathematical model of the converter is built using the averaging method applied on a dual time basis. The obtained parametric model, expressed in the (d, q, 0) rotating reference frame, is a fourth-order time-invariant system. Manifestly, the model parameters depend on the operating conditions. Simulation results are performed allowing the assessment on the relation´s existence between parameters and their corresponding operating disturbances. Then, a feedback linearization control approach is applied to the converter. Effects of main voltage shortening as well as sudden supply over voltage on both line current and DC output voltage are analyzed.