| Summary: | 博士 === 國立臺灣大學 === 電機工程學研究所 === 96 === Adaptive voltage positioning (AVP) technique has been used in multiphase voltage regulators for microprocessor power applications. It is a control scheme to increase the energy efficiency and reduce the output capacitor size of a DC power converter. The focus of the dissertation is on the control aspect of the AVP schemes.
The design philosophy of AVP control is very different from that of a conventional DC power converter. In such a design, the converter output impedance must be designed to be a prescribed constant value with respect to frequency. As a result, the control loop gain must be shaped in certain way to accomplish AVP. Besides the issue of output impedance, the issues of line regulation and control stability must also be considered at the same time. Without a detailed mathematical model, this is very hard to achieve.
In this dissertation, a novel scheme introduced in recent years, called AVP+, was for the first time analyzed. Small signal model was developed from which compensator design can be accomplished. The model has been verified by simulations and experiments. Comparisons were made of this scheme with two well-known conventional schemes, the current-mode scheme and the AVP- scheme. Compared to conventional AVP schemes, the AVP+ scheme provides better stability margin, better output impedance performance while maintaining good line regulation. This is especially true for the case of using ceramic output capacitors and high switching frequency, which is the prevailing trend of high-performance voltage regulators.
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