Dynamic performance enhancement of AC/DC PFC boost converters by means of MRAS observers

Controlling a Power Factor Corrected (PFC) boost converter is not a trivial task, because the higher the dynamic performance, the higher is the input current distortion. On the other hand, recent applications of these converters require fast transients in response to disturbances, such as sudden variations of load power, reference voltage and input voltage. Better performance can be obtained adding a feedforward action to the traditional control scheme, using observers to estimate the input voltage and the output current. However, the actual improvement depends on the dynamic performance of the chosen observers. This paper aims at evaluating the applicability and the performance of different classes of observers within the control scheme of a PFC boost converter. Several simulations are performed to identify the observer that exhibits the best dynamic performance. Then, the chosen technique is applied to a laboratory prototype of a PFC boost converter and the experimental results are discussed.