Browsing by Subject "pulsed power supply"
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Item Applying a Homopolar Power Supply to a Tokamak(1976-11) Wildi, P.; Hutchins, S; Driga, M.D.The new Texas Experimental Tokamak (TEXT) will use homopolar generators as a pulsed power source. The high current, low voltage output of such a source calls for unusual solutions to achieve a proper match to toroidal toil system and ohmic heating system. The paper discusses several possible alternatives. The solutions chosen for both the toroidal and the heating coil system are described including some of the salient components such as switches and power electronics.Item Characteristics of a Homopolar Machine as a Power Supply for Large Pulsed Magnetic Fields for Fusion Experiments(1973-04) Rowberg, R.E.; Becker, E.B; Rylander, H.G; Woodson, H.H.Inexpensive and reliable methods of storing and transferring large amounts of energy (>50 MJ) are essential to continued progress in controlled fusion research. One particularly attractive means of doing this, for slow time scale requirements (10-100 sec), is to use a homopolar generator in a pulsed mode of operation. A detailed design study of a 55 MJ homopolar machine to power the toroidal field of the Texas Turbulent Torus is being carried out at The University of Texas. This unit is designed to deliver a peak current of 35 kA, at 210 volts, to the field coils of the Texas Torus in 10 sec. In addition a 0. 7 MJ working bench model of the homopolar machine has been built and is currently being used to test the design of the large unit. These tests include mechanical considerations such as stress, bearing loading, and heating, and electrical considerations such as stability, speed control, and field compensation.Item Compulsator--A High Power Compensated Pulsed Alternator(1978-12) Weldon, W.F.; Driga, M.D; Bird, W.L; Tolk, K.M; Woodson, H.H; Rylander, H.G.Item Design Considerations in a 60 Caliber Electromagnetic Railgun System(IEEE, 1989-01) Fulcher, C. W.; Faidley, R. W.; Ingram, M. W.; Pratap, S. B.; Spann, M. L.A design code has been developed to aid in the development of a compact 60-caliber EM (electromagnetic) launcher system, based on a standard multivariable optimization technique. A lumped circuit model which was verified with a sophisticated performance program serves as the core of the code. The design code provides an optimum set of 13 compulsator rotor design parameters that minimizes the rotor mass subject to eight design constraints for a single railgun discharge. These design parameters are rotor radius, rotor length, armature conductor thickness, banding thickness, number of conductors per pole, launcher length, launcher inductance gradient, projectile velocity, generator voltage, maximum allowable decrease in rotor angular velocity, pulse width, electrical frequency, and firing angleItem The Design of Homopolar Motor-Generators for Pulsed Power Applications(1975-11) Weldon, W.F.; Driga, M.D; Rylander, H.G; Woodson, H.H.The need for inexpensive pulsed power for fusion research is becoming more intense as the size of these experiments rapidly increases. Nearly all experimental investigations now proposed require energy stores of hundreds of megajoules and some proposed reactors are in the gigajoule range. An engineering feasibility study at the University of Texas at Austin in 1972 suggested the use of a Faraday disc or homopolar machine for inertial energy storage. Such a machine can use a single rotor as the motor and generator armature as well as the flywheel at a considerable cost saving relative to separate units. A number of machines using this principle have been designed by the Energy Storage Group at the University of Texas at Austin and two have been built and tested. Both the 0.5 megajoule and 5 megajoule homopolar machines, built at the University of Texas at Austin, have exceeded their original performance goals. Initially the main advantages of such homopolar machines appeared to be the geometric simplicity of the field coil windings, the use of a rotor without windings, and the resultant low cost. At present another advantage seems to overshadow these in that rotors without windings can be rapidly accelerated to high speeds and can be discharged rapidly with an electrical release of virtually all of the inertial energy in time periods down to milliseconds. Present design studies and experimental research are concentrating on producing low inductance, low resistance, high speed machines with short current diffusion times. Current collectors for use at high speed (up to 450 m/sec) are under experimental investigation in a separate brush test facility. These studies and tests are summarized in a form to facilitate determining the compatibility of homopolar machines and specific loads.Item Electromagnetic Thrust Bearing for a Homopolar Machine--Theoretical Analysis(1974-05) Mustafa, S.F.; Driga, M.D; Rowberg, R.E; Woodson, H.H.Development of large, inertial pulsed power supplies is essential to the success of the controlled thennonuclear research program. A very attractive candidate for this supply is the homopolar motorgenerator which can produce the large current pulses (~lOOKA) necessary for the confinement and compression magnetic fields needed on the large fusion feasibility experiments. For a radial current flow, axial magnetic field configuration, the machine rotor is unstable to movement in the axial direction. Therefore a large mechanical thrust bearing is normally used which adds to the frictional losses and reduces the machine's efficiency. However, these losses could be reduced substantially by replacing the mechanical bearing with an electromagnetic thrust bearing. This is based on the principle of controlling the axial motion of the rotor by differential control of the two halves of the field. This report describes the theoretical analysis of such a system based on Maxwell's equations and the co-energy principle. The static force acting on the rotor and the inductance of the field coil are calculated as a function of the field current, the rotor displacement from magnetic center, and the differential current. Additionally the equation of motion of the rotor including the feedback control system which drives the differential current in the field coils is calculated. Results are obtained for two sets of initial conditions: 1) the rotor is initially displaced and 2) an initial impulse- like force is applied to the rotor in the axial direction. It is shown that for initial displacements less than lo- 3m and/or impulse forces less than 3Nt-sec stability can be achieved for the 0.5MJ homopolar machine presently in operation.Item Electromagnetic Thrust Bearing for a Homopolar Machine: Experimental Implementation(1974-05) Islam, Z.; Driga, M.D; Rowberg, R.E; Woodson, H.H.Development of large, inertial pulsed power supplies is essential to the success of the controlled thermonuclear research program. A very attractive candidate for this supply is the homopolar motorgenerator which can produce the large current pulses (~lOOKA) necessary for the confinement and compression magnetic fields needed on the large fusion feasibility experiments. For a radial current flow, axial magnetic field configuration, the machine rotor is unstable to movement in the axial direction. Therefore a large mechanical thrust bearing is normally used which adds to the frictional losses and reduces the machine's efficiency. However, these losses could be reduced substantially by replacing the mechanical bearing with an electromagnetic thrust bearing. This report discusses the experimental implementation of an electromagnetic thrust bearing on the 0.5MJ homopolar machine presently in operation at The University of Texas at Austin. A control system describing the electromagnetic thrust bearing is formulated and the system stability is determined. The circuitry is then described which produces the required differential field current and monitors the position of the rotor. The latter is done by a position sensing unit consisting of an LED and a phototransistor. The former is done with an operational amplifier circuit that generates equal and opposite voltages which drive the two SCR field supplies in a manner to create the required differential current. For a static rotor, test results show that a restoring force is generated and that the rotor can be stabilized against the axial forces.Item Fast Discharge Acyclic Machines(1975-04) Driga, M.D.; Nasar, S.A; Rylander, H.G; Weldon, W.F; Woodson, H.H.The paper discusses the feasibility of designing and developing fast discharge down to a few milliseconds range acyclic machines as pulse-power for experiments in controlled thermonuclear fusion, such as Reference Theta Pinch Reactor (R. T. P. R.). An equivalent circuit for the system (machine and the load) considered as a T.E M wave guide is derived. This equivalent circuit takes into consideration the penetration of the electromagnetic fieId in the rotor. Two basic topological alternatives of the acyclic machine are compared and performance and design equations are derived. The expressions relating the parameters of the short circuited machine with the parameters of the system through the coefficients of compatibility are given and the physical limitations are evaluated. Extrapolation of results obtained by discharging 0.55 million amperes from a 5MJ acyclic machine already built and preliminary stress calculations show that the fast discharge machines are feasible from mechanical considerations also.Item Final Manufacture and Assembly of a Modular 60 Megajoule Pulsed Homopolar Power Supply(IEEE, 1986-11) Noble, W L.; Weldon, J.M.; Gully, J.H.The Center for Electromechanics at the University of Texas at Austin (CEM-UT) has contracted Parker Kinetics Designs Inc. (PKD) to manufacture and install a modular 60 megajoule pulsed homopolar generator power supply located in the Electromechanics and Energy Building at Balcones Research Center, the University of Texas at Austin. (See Figure 1) The system consists of six (6) truncated drumtype homopolar generators, each s toring 10.0 megajoules rotational kinetic energy, at a speed of 6073 RPM (636 rad/sec.). (See Figure 2) Various allowable combinations of series and parallel output connections provide system flexibility. For a full series disharge, the predicted output is 600 VDC and 1.5 million amperes. Each homopolar generator has a minimum effective capacitance of 2000 Farads with a very low internal impedance of 7.1 microohms and 112 nanohenries. The Balcones Research Center 60 MJ pulsed homopolar power supply also includes a complete set of sophisticated auxiliary equipment designed to support the six homopolar generators. A complex, highreliability instrumentation and control system is incorporated into the power supply design to safely operate and monitor the performance of the generators. The auxiliary equipment and the instrumentation, control, and data acquisition systems are described in detail in the accompanying paper entitled >Final Design of the Control and Auxiliary Systems for the Balcones 60 Mj Homopolar Pulsed Power Supply>, authored by D.J. Hildenbrand, M.A. Pichot, and J.H. Price. This paper primarily deals with the manufacture and assembly of the LO MJ homopolar generators.Item The Homopolar Generator as a Pulsed Industrial Power Supply(1979-04) Weldon, J.M.; Weldon, W.F.Item Homopolar Generator Development at the University of Texas(1977-11) Weldon, W.F.; Rylander, H.G; Woodson, H.H.Item Homopolar Motor-Generator Inertial Energy Storage Systems(1974-03) Rylander, H.G.; Woodson, H.H.Item Hypervelocity Powder Deposition using Pulsed Power Magnetic Flux Compression Devices(IEEE, 2001-06) Driga, M.D.; Zowarka, R.C.This paper outlines two original concepts which, in combination, can bring fundamental advances to both manufacturing and materials technologies and the pulsed power approach to them, and describes a laboratory system already built which has conducted proof-of-principle experiments. The first novel concept uses a hypervelocity accelerator for a new thermal spray process using electromagnetic forces to accelerate powder particles to velocities of 2 km/s or higher, more than twice that of the powder velocities of about 1 km/s used by the existing state-of-the-art thermal spray processes (HVOF, D-gun, plasma spray) which are limited by their reliance on the thermodynamic expansion of gases. The second original concept is a pulsed power supply, a new electrical machine-flux compressor with precisely controllable output capable of matching ideally the powder spraying hypervelocity accelerator at any moment of time. Due to the compensation systems, the compulsators are low internal impedance machines designed for pulsed duty and capable of providing large current pulses, with a rapid rise time (in our case, less than 25 /spl mu/s to 80 MW pulsed power) to a low impedance load-a hypervelocity square bore railgun accelerator (SBA) assuring an almost continuous process. After describing the results of some experiments confirming system modeling and performance, the paper concludes with future directions of this research.Item Inexpensive Inertial Energy Storage Utilizing Homopolar Motor-Generators(1975-10) Weldon, W.F.; Woodson, H.H; Rylander, H.G; Driga, M.D.The pulsed power demands of the current generation of controlled thermonuclear fusion experiments have prompted a great interest in reliable, low cost, pulsed power systems. The Energy Storage Group at the University of Texas at Austin was created in response to this need and has worked for the past three years in developing inertial energy storage systems. 0.5 and 5 megajoule homopolar motor-generators have been designed, built and tested at the University of Texas and design studies have been completed for several systems ranging in size up to 63 gigajoules. The performance of the two laboratory machines and the potential applications which have been investigated are discussed.Item Investigation of the Homopolar Motor Generator as a Power Supply for Controlled Fusion Experiments(1973-11) Rylander, H.G.; Rowberg, R.E; Tolk, K.M; Weldon, W.F; Woodson, H.H.With the impending construction of large controlled fusion feasibility experiments, the need for reliable, inexpensive inertial energy storage to power the confinement magnetic field ls becoming more urgent. To investigate the possibility of using a homopolar machine for this task we have carried out a series of electrical and mechanical tests on a O. 5 MJ unit operating as a pulsed power supply. The machine ls motored up to a design speed of 6000 RPM using a 150 kW SCR power supply, and then, upon disconnecting the supply and connecting a load (short circuit), current pulses of up to 13 kA with a rise time of 25 ms are generated. The peak current and pulse decay time are limited by the armature circuit resistance, RA. This in tum depends primarily on the amount of rotor surface covered by the brushes which, in the ca1e of this machine, ls only 1% leading to a relatively high RA of 4 x 10-4 n. In addition, we observe that up to 80% of the stored energy ls delivered to the load. Motoring efficiencies are considerably less due to friction of the brushes and loading of the thrust bearing. In this connection we are testing an electromagnetic thrust bearing that is based on the principle of restoring the rotor to a position of magnetic equilibrium by differentially exciting field coils on each side of the central plane perpendicular to the axis of rotation. This process involves a photoelectronic device to sense the position of the rotor in order to control the field supplies. Based on results from our small model, we are in the process of constructing a 5 MJ single rotor machine capable of generating 100 kA at 5500 RPM and 45 volts. This model will have substantially higher motoring efficiency and lower armature circuit resistance. Design features of this machine are discussed.Item Magnetic Field Calculations for High-Energy Pulsed Power Supplies(1976-11) Becker, E.B.; Driga, M.D; Pillsbury, R.D; Rylander, H.G; Weldon, W.F; Woodson, H.H.The accurate calculation of the magnetic fields steady or rapidly varying is extremely important in designing pulsed power supplies for controlled thermonuclear fusion experiments, lasers, etc., where the traditional simplifying assumptions become unacceptable - especially when ferromagnetic materials in high magnetic fields are used. A finite element method for solution of Maxwell's equations for a moving media in terms of the magnetic vector potential and electrokinetic scalar potential describing the penetration of the magnetic fields in fast pulsing power supplies of electromechanical type is presented. The formulation for the steady-state magnetic fields in nonlinear media results as a particular case of the method. This approach was used for predicting the discharge parameter for the very fast discharging homopolar machine (FDX) designed by the Energy Storage Group at the University of Texas. FDX is in an advanced state of execution. This work was supported by the Electric Power Research Institute (EPRI) and the Energy Research and Development Administration (ERDA).Item Preliminary Engineering Design of a Pulsed Homopolar Generator Power Supply(IEEE, 1976-11) Bird, W.L.; Dase, W.G; Grant, G.B; Rylander, H.G; Tolk, K.M; Weldon, W.F; Woodson, H.H.A 200 megajoule 500 volt homopolar generator system is proposed as the inertial storage-conversion device for the Texas Experimental Tokamak (TEXT). The initial engineering design of a 50 megajoule 125 volt homopolar generator module is presented and major components: yoke/field coil; rotor/shaft/bearings; brushes and armature conductors are described in detail. The support for this work was provided by the Energy Research and Development Administration (ERDA) and the Texas Atomic Energy Research Foundation (TAERF).Item The Proposed CEM-UT 50-MJ Pulsed Homopolar Generator Power Supply(IEEE, 1982-01) Weldon, W.F.; Aanstoos, T.A.The Center for Electromechanics at the University of Texas at Austin (CEM-UT) has been involved since 1972 both in the development of homopolar generators (HPGs) as pulsed power supplies and in the application of these power supplies to a variety of loads. We have proposed that a 50-MJ HPG system be built as an experimental power supply for future CEM-UT research and development. This system will be part of a new research facility UT plans to build for CEM-UT at the UT Balcones Research Center. Originally the machine was to be a modified version of the 50-MJ HPG designed to power the UT Texas Experimental Tokamak (TEXT). However, recent developments by CEM-UT indicate that a modular approach offers greater performance flexibility. The attractiveness of modular construction is particularly en- hanced by the concurrent developItem Pulsed Energy Storage in Fusion Devices(1976-10) Thomassen, K.I.; Rogers, J.D; Ribe, F.L; Weldon, J.M; Swannack, C.E; Vogel, H.F; Rylander, H.G; Weldon, W.F; Tolk, K.M; Driga, M.D; Bird, W.L; Woodson, H.HResearch and development on pulsed energy technologies primarily for pulsed high-beta fusion systems, is described. Systems studies at Los Alamos and elsewhere have served to define these required technologies, which include fast discharging homopolar machines, pulsed superconducting coils, and the associated switching technology. Programs at the Los Alamos Scientific Laboratory, Westinghouse, and The University of' Texas are described here.Item Pulsed Homopolar Generator Research at the University of Texas at Austin(1977-10) Weldon, W.F.