Roger A. Dougal

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A compact digitally controlled fuel cell/battery hybrid power source is presented in this paper. The hybrid power source composed of fuel cells and batteries provides a much higher peak power than each component alone while preserving high energy density, which is important and desirable for many modern electronic devices, through an appropriately(More)
Solar photovoltaic (PV) arrays in portable applications are often subject to partial shading and rapid fluctuations of shading. In the usual series-connected wiring scheme, the residual energy generated by partially shaded cells either cannot be collected (if diode bypassed) or, worse, impedes collection of power from the remaining fully illuminated cells(More)
Hybrid power sources composed of fuel cells and secondary batteries can combine the high energy density of fuel cells with the high power density of batteries. A dc/dc power converter can be placed between the fuel cell and the battery to balance the power flow and greatly augment the peak output power. This paper presents a novel, flexible strategy for(More)
An actively controlled battery/ultracapacitor hybrid has broad applications in pulse-operated power systems. A converter is used to actively control the power flow from a battery, to couple the battery to an ultracapacitor for power enhancement, and to deliver the power to a load efficiently. The experimental and simulation results show that the hybrid can(More)
A review of mathematical models of lithium and nickel battery systems developed at the University of South Carolina is presented. Models of Li/Li-ion batteries are reviewed that simulated the behavior of single electrode particles, single electrodes, full cells and batteries (sets of full cells) under a variety of operating conditions (e.g. constant current(More)
Hybrid systems composed of fuel cells and batteries combine the high energy density of fuel cells with the high power density of batteries. A dc/dc power converter is placed between the fuel cell and the battery to balance the power flow between them and greatly increase the peak output power of the hybrid. This paper presents an adaptive control strategy(More)
Twenty-first century handheld electronic devices and new generations of electric vehicles or electric airplanes have fueled a need for new high-energy, high-power, small-volume, and lightweight power sources. Current battery technology by itself is insufficient to provide the mandatory long-term power these systems require. Fuel cells are also unable to(More)
A novel energy harvesting device called the energy coupler is proposed which can provide power to small wireless sensors in a power system. The energy coupler when coupled electromagnetically to a nearby current carrying conductor scavenges ac power from the conductor. The proposed energy coupler converts the harvested ac power into dc using a passive(More)