Showing papers on "Power optimizer published in 1987"

Unique computer power system with backup power

Abstract: A computer power system comprises an AC-to-DC power supply for providing DC power to the computer during the presence of AC line power and a backup power supply for providing DC power from batteries directly to the DC operated components of the computer system, completely bypassing the AC to DC power supply, when AC line voltage is absent or low.

Revolution control for wind power generator

Abstract: PURPOSE: To effectively utilize the power without discharging the power by connecting a flywheel onto the input shaft of a power generator turned by a wind power through a continuously variable transmission means and storing the power in the flywheel and supplying the accumulated power into the power generator. CONSTITUTION: The rotary shaft 2 of a propeller 1 turned by a wind power is connected with the input shaft 6 of a power generator 5 through the speed increasing gears 3 and 4. A blade pitch controller 8 is connected with the propeller 1, and the pitch angle of the propeller 1 is set to the pitch angle having the highest efficiency for outputting the average power according to the average wind speed calculated from the output of a wind speedometer 9. Further, a flywheel 14 is connected with the input shaft 6 through a continuously variable transmission means 13 in which a hydraulic pump 10 and a hydraulic motor 11 are connected through a hydraulic pipe 12. When the wind power exceeds the average wind speed, the excessive power is accumulated in the flywheel 14, and when the wind speed lowers below the average wind speed, the accumulated power is outputted. COPYRIGHT: (C)1988,JPO&Japio

Design and development of a 4-kW/2-kHz dc-isolated power conditioner for utility-interactive photovoltaic applications

Abstract: A utility-interactive inverter based on high-frequency isolation has been developed to provide a low-cost, compact, photovoltaic-to-utility interface at the residential power level of 4 kW. A single-quadrant, dc-isolated, push-pull buck converter switching at 20 kHz is used to generate a full-wave rectified sine wave that is subsequently unfolded by a low-speed, four-transistor bridge to result in a 60-Hz sine wave power output. A control strategy optimizing the output impedance of the inverter for the direct interface to the stiff utility voltage has been developed. A novel peak power tracking circuit based on the inherent 120-Hz input voltage ripple continuously follows the peak power without artificial operating point dither. Inverter shut-down after line disconnection is ensured, fully protecting the serviceman, even when the solar power available exactly matches a unity power factor load. Despite its low weight of only 17 kg, the inverter is 92% efficient. 5 refs., 60 figs., 7 tabs.

A high power-density DC-DC converter board

Abstract: A series of multiple output, 500 Watt, dc-dc converter boards for use in a 3kW computer power system is described. High power-density (9 Watts/cu.in. including heatsinks) is achieved through the use of thick film hybrid modules and a 316kHz switching frequency. The system considerations, design tradeoffs, and problems encountered are described. Future considerations for further enhancements to performance are proposed.

A DC/DC Converter for ISDN Terminals

Abstract: In the field of power conversion for telecommunication equipment, ISDN involves various problems. One of them is to achieve the required efficiency of the DC/DC converter used to supply low power terminals such as digital telephones connected to the "S" bus. SAT has developped such a converter to equip digital telephone terminals designed for RENAN (the French experimental digital network). To fulfil the requirement of high efficiency in a wide range of output power and specially at very low output power, this converter works in two different modes : - free running frequency with fixed pulse-width for low power output corresponding to the stand by state of the terminal - fixed frequency PWM for higher output power corresponding to active states of the terminal. The control circuitry is achieved by simple low cost low power components.

Wind-Generators in Hybrid Systems Powering Remote Telecommunication Sites in the Far North

Abstract: As indicated in the title this paper deals with the experience attained from operation of hybrid power systems (i.e. systems relying on multiple sources of energy to ascertain continuous operation of telecom equipment with one or more inactive power sources), incorporating wind generators in remote telecom stations located in an arctic environment. Although the functional layout of such systems will exhibit similarities disregarding location, this description is based on the specific layout of Norwegian/Scandinavian sites with special emphasis on the test sites operated by the Norwegian Telecommunications Administration (NTA), the sites being listed in Table 1. The hybrid systems under test are without exception relying on wind and/or solar energy as the primary power source, backed up by stationary (lead-acid) batteries and/or one or more fossil fuel-driven (mostly diesel) generators and a control unit that has a bilateral function, one of which being the switching between the different power sources when required, the second being an "intelligent" utilization of surplus or "waste" energy. It is self-evident that the focus in this test program is particularly on the reliability of system components prone to mechanical wear, i.e. the wind-generator and also the control system. The aim of this discussion is to extract the essential information from the experience gained so far and how this will affect further integration of similar systems.