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 nonminimum 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