Minimum Time Control for Multiphase Buck Converter: Analysis and Application

• Published in: IEEE transactions on power electronics 2014-02, Vol.29 (2), p.958-967
• Main Authors: Pengming Cheng, Vasic, Miroslav, Garcia, Oscar, Oliver, Jesus Angel, Alou, Pedro, Cobos, Jose Antonio
• Format: Article
• Language: English
• Subjects: Applied sciences; Buck converters; Capacitors; Charge balance; Circuit properties; Converters; Convertors; Electric currents; Electric potential; Electric power; Electric, optical and optoelectronic circuits; Electrical engineering. Electrical power engineering; Electrical equipment; Electrical machines; Electronic circuits; Electronics; envelope amplifer; Equations; Exact sciences and technology; Inductors; Input output; Mathematical model; Microwave circuits, microwave integrated circuits, microwave transmission lines, submillimeter wave circuits; minimum time control; Multiphase; multiphase converter; Power electronics, power supplies; Radio frequencies; Ripples; Signal convertors; Switches; Transient analysis; Voltage; Voltage control; voltage variation
• ISSN: 0885-8993; 1941-0107
• DOI: 10.1109/TPEL.2013.2256798

The combination of minimum time control and multiphase converter is a favorable option for dc-dc converters in applications where output voltage variation is required, such as RF amplifiers and dynamic voltage scaling in microprocessors, due to their advantage of fast dynamic response. In this paper, an improved minimum time control approach for multiphase buck converter that is based on charge balance technique, aiming at fast output voltage transition is presented. Compared with the traditional method, the proposed control takes into account the phase delay and current ripple in each phase. Therefore, by investigating the behavior of multiphase converter during voltage transition, it resolves the problem of current unbalance after the transient, which can lead to long settling time of the output voltage. The restriction of this control is that the output voltage that the converter can provide is related to the number of the phases, because only the duty cycles at which the multiphase converter has total ripple cancellation are used in this approach. The model of the proposed control is introduced, and the design constraints of the buck converter's filter for this control are discussed. In order to prove the concept, a four-phase buck converter is implemented and the experimental results that validate the proposed control method are presented. The application of this control to RF envelope tracking is also presented in this paper.