51 research outputs found
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Rotating Machine Technologies for Integration of Pulsed and High Power Loads in Naval Electric Power Systems
Advanced electric sensors and weapons are placing increasing demands on the electric power distribution systems of future naval vessels and energy storage is viewed as a critical technology for effective integration of IPS architectures in these platforms. This paper shows that kinetic energy storage, i.e. stored in the angular momentum of a rotating mass, can be applied in differing topologies to address a range of ship power system applications. Rotating machine technologies are presented for UPS and load leveling applications as well as for high cycle rate pulsed power applications.Center for Electromechanic
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Iron Core Compulsators for Railgun Power Supplies
Recent development efforts on compulsator based railgun power supplies have been focused on lightweight, composite, self-excited machines. However, operating experience with the Iron-core (ferromagnetic) compulsator at the Center for Electromechanics at The University of Texas at Austin (CEM-UT) has shown it to be extremely reliable and much more versatile than originally envisioned. Furthermore, recent experiments with high current solid state switches and studies or staged multiple compulsator discharges have made multiple compulsator installations attractive. For railgun installations where generator weight and volume are not primary concerns, multiple iron-core compulsators can provide a low cost, extremely versatile power supply. The design of such a system is presented, incorporating many or the most attractive features or advanced compulsator concepts. These Include: direct connection to mechanical prime power, Inherent power averaging, low jerk flat top current pulses producing high acceleration ratios, reclamation of the railgun magnetic energy with attendant elimination or muzzle arc, and rapid fire operation.Center for Electromechanic
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An Application Guide for Compulsators
Focus toward advanced mobile tactical configurations for railgun power supplies has resulted in the evolution of five compulsator generations in the past 15 years. Unfortunately, the rapid maturation of the technology has tended to dilute the relative importance and application base of previous generations. Technical variance between generations has been significant, including air-core or iron-core, rotating armature or field, single- or multiphase, solid rotor or shell, and externally excited or self-excited. It is useful, therefore, to review and classify the important distinctions between the generations of machines, thus allowing proper selection of the one best suited for a given application. This paper provides an overview of the evolution of compulsators developed at The University of Texas at Austin Center for Electromechanics. Features of past and present configurations are discussed, such as machine topology, method of excitation, basic switching methods, discharge pulse shapes, and potential energy and power densities. A list of potential applications is generated for all disciplines within the armed forces. This information is used to create an application guide that can be used to select appropriate compulsator options for the mission given. An extensive list of references is also provided.Center for Electromechanic
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Nine-Phase Armature Windings Design, Test, and Harmonic Analysis
A nine-phase armature winding was developed for a large generator. Alternative methods for interconnecting the pole-phase groups were examined. An alternate-pole connection scheme was adopted and a prototype induction motor was constructed to confirm the winding scheme. Since only a three-phase power source was available for testing, the induction motor was tested by using three, three-phase winding sections, one at a time. Air-gap harmonic fields produced some unusual results. These test results and harmonic analyses to explain them are presented herein. The tests confirmed the nine-phase winding scheme that was adopted. The harmonic analyses revealed that the complete nine-phase winding exhibited a very low harmonic content, a distinct advantage of a nine-phase winding for future applications.Center for Electromechanic
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Power Supplies for Airborne Laser Systems
This paper investigates the power supply options for an airborne laser system (solid state laser diodes). The application demands a power supply capable of a high repetition rate (1,428 pulses per engagement over 2 s) and delivering total energy of 20 MJ (i.e. 14 kJ per pulse). The high repetition rate precludes the use of capacitors. Hence rotating machines storing inertial energy appear to be the most viable option. In this paper the compensated pulsed alternator (compulsator) invented by the Center for Electromechanics at the University Of Texas (CEM-UT) at Austin is examined as a possible power supply option for the above application. The laser system is characterized as a 1.25 m (ohm) resistive load. In the past the compulsator has been examined essentially for inductive loads like the railgun aid hence the analysis presented here throws new light on the capabilities of the compulsator. Several configurations involving the compulsator are evaluated in this paper viz. two machines operating in parallel, a single machine storing all the energy and an external flywheel storing the required energy with compulsator serving as a energy conversion device. The paper explores the lower limits on the compulsator size and weight for the different configurations.Center for Electromechanic
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Single and Multiphase Compulsator System Architectures: A Practical Comparison
The Center for Electromechanics at the University of Texas at Austin (UT-CEM) has designed, built, and tested three generations of iron-core and air-core compensated pulsed alternators (CPA). These include the iron core, small caliber, cannon caliber, and model scale compulsators. Early CPA were single-phase machines that were optimized for a specific load and desired performance. The most recent machine, the model-scale CPA, is a multiphase alternator coupled to the load through a rectifier. This paper includes a discussion of the requirements and capabilities of both single-phase and multiphase systems, a point design for each system type, and a comparison of system performance in driving a cannon caliber launcherCenter for Electromechanic
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Rotating Machine Development at The University of Texas
The Center for Electromechanics at The University of Texas at Austin (CEM-UT) is specialized in the development of high power, pulsed rotating machines for a variety of applications including fusion experiments, directed energy devices, and electrothermal and electromagnetic accelerators. For many of these applications, compulsators have emerged as viable power supplies. These machines are low impedance alternators which use flux compression to shape the discharge pulse and increase peak power and, to date, have been constructed from ferromagnetic materials. In the past several years, tremendous gains in energy and power densities have been predicted based on the use of composite materials. Glass, graphite, boron and Kevlar reinforced epoxy systems have the advantage of superior strength and stiffness, and are much lighter when compared to their metal counterparts. Two major efforts in which composite based (air-core) compulsators are being developed are now coming to fruition. Additionally, conceptual designs of several advanced concepts covering a wide range of pulse lengths and applications have been performed. The purpose of this paper is to report on the status of the machines currently being fabricated and describe the next generation of high performance compulsators.Center for Electromechanic
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Air-Core Compensated Pulsed Alternators
A compensated pulsed alternator is a generator capable of delivering high power energy pulses with current waveform flexibility. This versatile machine has applications in various fields where power density is at a premium. Recent advances in applying fiber/epoxy composites to rotating electrical machinery [l] have greatly enhanced the power density capabilities of this machine. A characteristic of these new machines is an absence of ferromagnetic material in the magnetic circuit, and they are therefore referred to as >air-core'' compulsators. This paper discusses the topological considerations and the capabilities of the family of machines called the air-core compulsators.Center for Electromechanic
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Operating Modes for Compulsator Based Electromagnetic Launcher Systems
The compensated pulsed alternator (compulsator) is a versatile power supply capable of interfacing with the electromagnetic launcher in various ways. The method that has been explored at length with several systems is the single phase option. Several variants of this option, some using advanced pulse shaping techniques, have been discussed in prior publications [I-3]. Besides this basic single pulse method of operating there are several other methods each with its pros and cons. The multi-phase option is discussed in this paper. Within the broad class of multi-phase systems there are further sub-classes, namely alternating current drive and unidirectional current drives. Thus the branching of these operating modes gives rise to a variety of operating modes. Each one of these operating modes is described and simulation results are presented.Center for Electromechanic
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Advanced Compulsator Technology
Compulsator selection issues are addressed, including two poles vs. four poles, shell vs. conventional rotors, relation between pulse shape and energy density, and would compensation. Electrothermal guns require a current profile which is quite different from that of their electromagnetic counterparts. A new method of obtaining this current pulse is discussed. This new variant also facilitates the self-motoring of the machine between bursts. This machine as applied to a 60 mm electrothermal chemical (ETC) gun is discussedCenter for Electromechanic
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