Modeling Issues in Three-Phase Current Source Rectifiers that use Damping Resistors

The model of a Three-Phase Current Source Rectifier (CSR) is a complex mathematical representation as it is non-linear, multi-variable, and coupled. In order to work with a simplified but still accurate model, a representation in a rotating reference frame \Vertdq0\Vert in combination with an average model are normally used. The result is a model that operates with ripple free inputs, outputs, and state variables that should be the accurate average value of the actual variables. However, the average model of these topologies could lead to errors if damping resistors are used. A case study shows as much as 10% error in the DC link current between the actual value and the predicted by the average model. This paper finds and shows systematically the source of the error and proposes a method for the accurate average modeling of CSRs with damping resistors. Simulated results show the validity of the theoretical considerations.