Aplicação do controle baseado em passividade em conversores estáticos operando como préreguladores de fator de potência

Abstract

This work studies a passivity based control approach applied to a switch-mode converters, specially the non isolated step-down (buck) converter operating in continuous conduction mode. Passivity is funded in energy concepts and consists in adjusting the system storedenergy in order to achieve stability. Two different techniques are described: First, the direct output voltage control through thevirtual addition of dissipative element in parallel with the load; second, the indirect output voltage control through the control of the inductor current with the virtual addition of a dissipative element in series with the converter inductor. This study aims at comparing both methods and also to evaluate the impact of the control parameters in the dynamic andsteady state behavior of the circuit. In addition, an adaptive scheme to estimate the unknown load conductance on line is proposed.Simulation and experimental results are provided, showing how the control gains affect the system performance and indicating a controller tuning strategy which is independent of the converter operating point. On the other hand, these results validate the studied approach inthe application pursued, which is the power factor correction. Both, the synchronization of the input voltage and current (the power factor correction) and the output voltage regulation are achieved.