Liquid‐metal‐cooled curved‐crystal monochromator for Advanced Photon Source bending‐magnet beamline 1‐BM

The authors describe a horizontally focusing curved-crystal monochromator that invokes a 4-point bending scheme and a liquid-metal cooling bath. The device has been designed for dispersive diffraction and spectroscopy in the 5--20 keV range, with a predicted focal spot size of {le} 100 {micro}m. To minimize thermal distortions and thermal equilibration time, the 355 x 32 x 0.8 mm crystal will be nearly half submerged in a bath of Ga-In-Sn-Zn alloy. The liquid metal thermally couples the crystal to the water-cooled Cu frame, while permitting the required crystal bending. Calculated thermal profiles and anticipated focusing properties are discussed

Active Magnetic Bearings for Energy Storage Systems for Combat Vehicles

Advanced energy storage systems for electric guns and other pulsed weapons on combat vehicles present significant challenges for rotor bearing design, Active magnetic bearings (AMBs) present one emerging bearing option with major advantages in terms of lifetime and rotational speed, and also favorably integrate into high-speed flywheel systems. The Department of Defense Combat Hybrid Power Systems (CHPS) program serves as a case study for magnetic bearing applications on combat vehicles. The University of Texas at Austin Center for Electromechanics (UT-CEM) has designed active magnetic bearing actuators for use in a 5 MW flywheel alternator with a 318 kg (700 lb), 20000 rpm rotor. To minimize CHPS flywheel size and mass, a topology was chosen in which the rotating portion of the flywheel is located outside the stationary components. Accordingly, magnetic bearing actuators are required which share this configuration. Because of inherent low loss and nearly linear force characteristics, UT-CEM has designed and analyzed permanent magnet bias bearing actuators for this application. To verify actuator performance, a nonrotating bearing test fixture was designed and built which permits measurement of static and dynamic force. An AMB control system was designed to provide robust, efficient magnetic levitation of the CHPS rotor over a wide range of operating speeds and disturbance inputs, while minimizing the occurrence of backup bearing touchdowns. This paper discusses bearing system requirements, actuator and controller design, and predicted performance; it also compares theoretical vs. measured actuator characteristicsCenter for Electromechanic

Design and analysis of a 20 MW propulsion power train

The electric ship research program at the University of Texas at Austin focuses on the development of power system technology for future electric ships. The main goal of the on-going research activity is to identify critical, high pay-off technology development needed to enable major improvement, in size and functionality, of navy ships power systems. Initial efforts were directed towards the establishment of a baseline power train which highlights various constraints and provides a basis for later optimization efforts. A 20 MW power train system was chosen for such a baseline, and all components, from fuel to propulsion motor, were considered and their impact on the whole power system assessed. The baseline design consists of a 25 MVA/3600 rpm radial flux permanent magnet generator, a 22 MVA PWM converter, and a 20 MW/150 rpm radial flux permanent magnet motor, along with the amount of fuel sized for an assumed mission profile, and the widely used LM2500 gas turbine. The analysis shows that fuel is by far the dominant component contributing to weight and volume and, consequently, overall efficiency of power train components is the most relevant parameter to reduce weight and volume. The 3600 rpm generator is the smallest component. The 150 rpm motor is the heaviest component, other than fuel, weighing close to 100 tonnes.Center for Electromechanic

Optimization of gas turbine generator-sets for improved power density

Many future U.S. Navy ships will employ all-electric propulsion systems instead of mechanical drives. To help optimize performance of these systems, studies are under way at The University of Texas at Austin Center for Electromechanics (UT-CEM) to minimize the size of power generation components. These studies focus on increasing the power density of directly coupled gas turbines and generators (gen-sets). The approach adopted in this paper uses scaling laws of gas turbines and synchronous electrical generators to examine the possibility of increasing power density by operating at higher shaft speeds. Included is consideration of inlet and exhaust turbine ducts and issues involving power electronics. Study results indicate that if inlet and exhaust duct volumes are neglected, the power density of directly coupled gas turbine-generator sets can be significantly improved by scaling to higher operating speeds. However, the advantages of scaling to higher speeds are largely negated when duct volumes typically encountered on modern ships are included. This suggests locating power generation equipment near the ambient terminus of inlet and exhaust ducts, so that duct lengths are minimized and fully exploiting the power density advantages of scaling to higher shaft speeds becomes possible.Center for Electromechanic

Inside-Out Configuration Active Magnetic Bearing Actuators

The University of Texas Center for Electromechanics (UT-CEM) has designed active magnetic bearing actuators for use in a 5 MW flywheel alternator with a 700 lb (318 kg), 20,000 rpm rotor, under the sponsorship of the Department of Defense Combat Hybrid Power Systems (CHPS) program. Because this machine incorporates an unusual inside-out topology (i.e., the rotating portion of the flywheel is located outside the stationary components), unique inside-out configuration magnetic bearing actuators are required. Permanent magnet bias bearings were chosen for this application because of inherent low power requirements, low power losses, and nearly linear current stiffness and positional stiffness. To verify performance, a bearing test fixture was designed and built which permits static and dynamic force measurement. This paper discusses bearing requirements, actuator design, predicted performance, and compares theoretical versus measured bearing characteristics. A companion paper discusses control issues for this unique magnetic bearing system.Center for Electromechanic

Development of Electric Propulsion Motors with Integrated Power Electronics

The effective integration of electric power in future naval ships requires the development of technologies that allow for volume and mass reduction of critical components. The University of Texas at Austin Center for Electromechanics is studying the potential for volume and mass reduction through the integration of power electronics into an electric propulsion motor. Two conceptual designs of a motor with integrated power electronics are presented. Integration of power electronics into the motor frame offers space saving advantages, allowing the motor and power electronics to share the same housing and cooling system. Accordingly, significant mass and volume reductions are possible in the power electronics housing and cooling auxiliaries.Center for Electromechanic

The possible occurrence of multi-phase behavior in the high T sub c superconductor YBa sub 2 Cu sub 3 O sub x

We report here the results obtained for powder diffraction studies on four YBa{sub 2}Cu{sub 3}O{sub x} samples in which a model with two orthorhombic phases was used to obtain an improved agreement. The implications of this structural model on the systematic variation of {Tc} with oxygen content will be discussed. 28 refs., 3 figs., 2 tabs