A Digital Control Scheme for Improving Transient Response and Light Load Efficiency of Multiphase DC/DC Converters
Date Issued
2012
Date
2012
Author(s)
Su, Jen-Ta
Abstract
In this dissertation, a digital control scheme is proposed to improve the transient response and light load efficiency of multiphase DC/DC converters. The proposed control scheme is based upon gain scheduling scheme which uses pole-zero cancellation method to adaptively auto-tune parameters of the compensator to efficiently improve the output transient response. The gain scheduling is a practical and useful adaptive control method. It requires some knowledge about the plant and some auxiliary measured variables. A great advantage of this method is that the controller adapts quickly to changing conditions. Moreover, a phase-shedding function is also designed in this control scheme. More specifically, the phase shedding is realized by a numerically stored power switch thermal characteristics look-up tables and a phase configuration selector for comparing the power loss of the present phase configuration with that of the assumed various phase configurations to determine whether the phase shedding should be operated or not. The design can be easily adapted to different technologies or modification to fulfill a new set of specifications with fast time-to-market.
Having the improved transient response, then the output capacitance can be significantly reduced by the proposed control scheme. Furthermore, the phase shedding function makes a significant improvement in light load efficiency with minimum in overall power loss of DC/DC converter. The proposed digital control scheme is implemented on an interleaving two-phase DC/DC synchronous buck converter with 12 V input, 1.2 V output, and 40 A load current. Simulation and experimental results are presented to demonstrate the effectiveness of the proposed scheme.
Subjects
gain scheduling
pole-zero cancellation
phase shedding
look-up table
light load efficiency
DC/DC converters
Type
thesis
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