Publication Date

12-2015

Date of Final Oral Examination (Defense)

10-15-2015

Type of Culminating Activity

Thesis

Degree Title

Master of Science in Electrical Engineering

Department

Electrical and Computer Engineering

Supervisory Committee Chair

Said Ahmed-Zaid, Ph.D.

Supervisory Committee Member

Vishal Saxena, Ph.D.

Supervisory Committee Member

Kurtis Cantley, Ph.D.

Abstract

Dual-input DC-to-DC converters are power supplies that draw power from two sources simultaneously and deliver power to a single load, the ratio of power drawn from each source and be held constant with changes in the load. Applications for dual-input power supplies are computer systems, mobile systems using energy harvesting, and systems needing redundant power supplies. This writing covers the operation and control of dual-input DC-to-DC converters that implement a non-inverting buck-boost function and utilize only a single power path.

Traditionally, a dual-input power supply is created by placing two standard power paths in parallel. This adds considerable control complexity associated with synchronizing the two converters. Four new power path topologies are presented: dual-input four-FET buck-boost, dual-input zeta, dual-input SEPIC, and alternate dual-input SEPIC. The single power path approaches require fewer components than the traditional approaches, however, the efficiency is slightly lower.

These converters can be controlled using any of the standard power supply control approaches, including: voltage mode, current mode, and constant on-time. Each control method does need to be modified slightly. The biggest difference in the control of these converters is in the logic that is used to control the switches in the power path. The ratio of current drawn from each input source can be held constant and can be adjusted in an open loop fashion if some variability is allowed, otherwise a sensor and feedback control can be implemented to fix the input current or input power ratio.

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