Control of a Three-Phase PWM Rectifier Based on a Dual Single-Input Single-Output Linear Model

A state-space-averaged model of a three-phase boost-type PWM rectifier is available in literature. The model is complex with a multi-input multi-output (MIMO) non-linear structure and a non-minimum phase feature. However, such a MIMO non-linear system becomes a dual single-input single-output (SISO) linear system by ignoring certain dynamics and applying a simple feed-forward de-coupling controller. In addition, the non-minimum phase feature is also eliminated in the resultant model. Investigation into the dual SISO model shows that such a model is valid during both steady-state and transient operation provided the closed-loop bandwidth of voltage controller is much less than the corner frequency of the right half plane (RHP) zero which is the cause of the non-minimum phase feature. Thus, the paper presents the range of validity of the proposed dual SISO linear model. A cascaded controller is then implemented in a back-stepping style based on the proposed model. Simulation studies have been carried out to show the effectiveness of the proposed controller and also to illustrate how the non-minimum phase feature affects the behavior of rectifier. The simulation results verify the theoretical predictions.