Voltage regulation in an interleaved circular chain sliding mode controlled multiphase converter

Abstract

In this article a multiphase synchronous buck converter controlled by a sliding mode control (SMC) in a circular chain control (CCC) configuration is presented. The proposed switching functions with the CCC architecture ensure a robust output voltage regulation when facing changes in the load or the input voltage, while providing current equalization among the phases. The novelty of the work is the simple control structure based on a first order SMC implemented by means of hysteresis-band comparators, requiring no external signals or additional hardware to lead the system to an interleaving operation, obtaining a harmonic cancellation that allows the size reduction not only of the output capacitor but also of the inductors. It is proved that, in the steady state, the switching function exhibits a periodic solution with a period equal to the switching period. Besides, the steady-state switching frequency expression as a function of the hysteresis bandwidth is derived. The work includes the analytical analysis of the proposed solution, a set of numerical simulations and, finally, an experimental validation. The numerical and experimental results confirm the predicted good performance of the proposed control.