Robust nonlinear adaptive control of multiphase synchronous buck power converters

The problem of controlling multiphase synchronous buck power converters is considered. The aims are to regulate the output voltage of the converter and to ensure adequate current sharing between its different channels. Using the backstepping technique, an adaptive controller is designed based on a large-signal bilinear model of the whole multi-channel converter. A parameter projection is used to ensure that the obtained adaptive controller is robust to parasitic resistances. The controller is formally shown to meet the objectives of closed-loop asymptotic stability, output reference tracking, and equal load sharing. The attraction region depends on the uncertain parasitic impedance size, with the attraction region being larger for smaller parasitic impedances. In the ideal case of no parasitic impedances, the closed-loop asymptotic stability is global. These theoretical results are confirmed by simulation. (C) 2009 Elsevier Ltd. All rights reserved.