Beat-Frequency Oscillations in Multiphase Interleaved Voltage Regulators with High-Gain Peak-Current Control Scheme
Date Issued
2010
Date
2010
Author(s)
Chiu, Chen-Hua
Abstract
Interleaved buck converters have been popularly used in the voltage regulators for powering the recent central processing units (CPUs) used in computer with energy-saving features. An interleaved power converter configuration features high efficiency, fast transient responses, distributed power dissipation, and easy modularity. Combining these features with the energy-saving measures adopted in recent CPUs such as dynamic loading and adaptive-voltage-position (AVP) really makes the whole computer system energy-efficient. However, the combination of an interleaved converter configuration and the dynamic CPU load may cause serious problems with phase current oscillating at beat frequency; i.e., the difference frequency of the converter switching frequency and the dynamic-load frequency. The focus of this thesis is to investigate such a problem in a recently reported High-Gain Peak Current Control (HGPCC) scheme. HGPCC is an attractive scheme for achieving AVP control which has been used in recent years to reduce the CPU losses in computers applications.
In the thesis, a multi-frequency model of the pulse-width-modulator was used in the modeling of this converter to take into account the feedback control effects of side-band signal (i.e., the beat-frequency signal) into considerations. A review of the oscillation problems was given for the conventional voltage-mode and peak-current-control interleaved converters. The HGPCC configuration was then modeled in details. It was concluded from the modeling effort that the HGPCC scheme has no suppression effect on the beat-frequency oscillation. A modified HGPCC configuration was then proposed to mitigate this problem while retaining all the basic features of original HGPCC. Simulations and experimental results were presented at the end to verify the model and the validity of the proposed modified HGPCC. Future research directions were also pointed out at the end of the thesis.
Subjects
interleaved power converter
dynamic load
beat-frequency oscillation
high-gain peak-current control
multi-frequency model
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