Average modeling of three-phase and nine-phase diode rectifiers with improved AC current and DC voltage dynamics

This paper presents a new average modeling approach for three-phase and nine-phase diode rectifiers with improved AC and DC dynamics. The key assumption taken in this paper is to model the DC load current using its first-order Taylor series expansion throughout the entire averaging timespan, i.e., commutation and conduction periods. The resultant average models present an excellent steady-state and transient behavior, matching their respective detailed switching models with less than 1 % measured error. Moreover, the analytic nature of these models makes them suitable for simulation and stability studies of variable frequency power systems. The paper presents an in-depth description of the modeling approach, together with a thorough static and transient validation of the proposed models. The model is validated through comparison of average model in MATLAB, switching model in Saber and the experimental results