Digital-Control-Based Solution to the Effect of Nonidealities of the Inductors in Multiphase Converters

Multiphase is an old technique that, nowadays, is widely used in several dc-dc applications such as voltage regulator module and automotive. The number of phases is usually kept relatively low (three or four) in most cases. However, the advantages of multiphase converters (mainly the reduction of input and output filters with its associated increase in maximum control bandwidth) grow with the number of phases in the ideal case. This growth is limited by nonidealities, mainly the tolerances of components (semiconductors and inductors). The purpose of this paper is to evaluate the effect of tolerances of the inductance on the current ripple. This nonideality causes the loss of two important advantages of multiphase converters, such as very high frequency and very low amplitude current ripple. The use of digital control can help to reduce drastically this problem. A simple algorithm, based on changing the triggering sequence of the phases, allows a big reduction of the impact of this nonideality. Experiments are included in the paper.