Avoiding a Voltage Sag Detection Stage for a Single-Phase Multilevel Rectifier by Using Control Theory Considering Physical Limitations of the System

The use of control theory in power electronics applications is aimed toward several objectives, which include, obtaining a good dynamic response, stabilizing in an operation point, regulation of state variable, reference tracking, rejecting of disturbances and robustness against parametric variations. It is also possible to eliminate stages that represent computational effort via control theory without loss of the main desirable characteristics. However, it should be considered the physical limitations of the topology given that even with sophisticated controllers they cannot achieve the established objectives if these limitations are exceeded. This paper aims at highlighting the importance of physical limitations of a single-phase multilevel rectifier (SPMR) using a nonlinear controller, an aspect not considered in previous works published by the authors. Thus, the design here presented is based on input-output linearization via feedback combined with a generalized PI controller. These controllers are used because they allow avoiding a voltage sag detection stage without changing the main characteristics of the topology. The procedure to reproduce these results is shown and the feasibility of the method is demonstrated by simulation and experimental results in a 1 kVA SPMR prototype.