Analysis and simulation of digitally-controlled grid-connected PWM-converters using the space-vector average approximation

A technique to evaluate the dynamic performance of control principles for PWM-converter systems is presented. In the modelling of vector-controlled, grid-flux-oriented control systems, nonlinear switches and time-varying elements due to coordinate transformation occur in the feedback loop. By using space-vector averaging, coordinate transformations and nonlinear switches are avoided. A linear time-invariant analytical model in the grid-flux-oriented dq-frame is derived. Simulations with a switched PWM-model and an analytical model show accurate transient response and frequency response.