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  • 1
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    Issues and status of power distribution options for space exploration (1991)
    In:  CASI
    Details
    Publication Date: 2013-08-29
    Description: The Space Exploration Initiative (SEI) will need a wide variety of manned systems with requirements significantly different than those for existing systems. The concept of a space power utility is discussed and the impact of this concept on the engineering of space power systems is examined. Almost all existing space power systems use low voltage direct current. Although they have been very succesful, increasing power system requirements in recent years have exposed their inherent limitations and led to the proposal of a number of alternatives including high voltage DC and AC at various frequencies. Drawing on the experience gained from Space Station Freedom and SEI systems studies, factors that may affect the choice of frequency standards on which to build such a space power utility are discussed.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: ESA, European Space Power Conference. Volume 1: Power Systems, Power Electronics, Batteries and Fuel Cells; p 375-380
    Format: text
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    NASA TECHNICAL REPORTS
  • 2
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    Flywheel Charge/Discharge Control Developed (2001)
    In:  CASI
    Details
    Publication Date: 2018-06-02
    Description: A control algorithm developed at the NASA Glenn Research Center will allow a flywheel energy storage system to interface with the electrical bus of a space power system. The controller allows the flywheel to operate in both charge and discharge modes. Charge mode is used to store additional energy generated by the solar arrays on the spacecraft during insolation. During charge mode, the flywheel spins up to store the additional electrical energy as rotational mechanical energy. Discharge mode is used during eclipse when the flywheel provides the power to the spacecraft. During discharge mode, the flywheel spins down to release the stored rotational energy.
    Keywords: Spacecraft Propulsion and Power
    Type: Research and Technology 2000; NASA/TM-2001-210605
    Format: application/pdf
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  • 3
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    Stator and Rotor Flux Based Deadbeat Direct Torque Control of Induction Machines (2003)
    In:  CASI
    Details
    Publication Date: 2018-06-06
    Description: A new, deadbeat type of direct torque control is proposed, analyzed and experimentally verified in this paper. The control is based on stator and rotor flux as state variables. This choice of state variables allows a graphical representation which is transparent and insightful. The graphical solution shows the effects of realistic considerations such as voltage and current limits. A position and speed sensorless implementation of the control, based on the self-sensing signal injection technique, is also demonstrated experimentally for low speed operation. The paper first develops the new, deadbeat DTC methodology and graphical representation of the new algorithm. It then evaluates feasibility via simulation and experimentally demonstrates performance of the new method with a laboratory prototype including the sensorless methods.
    Keywords: Numerical Analysis
    Format: text
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    NASA TECHNICAL REPORTS
  • 4
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    New Technique of High-Performance Torque Control Developed for Induction Machines (2003)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: Two forms of high-performance torque control for motor drives have been described in the literature: field orientation control and direct torque control. Field orientation control has been the method of choice for previous NASA electromechanical actuator research efforts with induction motors. Direct torque control has the potential to offer some advantages over field orientation, including ease of implementation and faster response. However, the most common form of direct torque control is not suitable for the highspeed, low-stator-flux linkage induction machines designed for electromechanical actuators with the presently available sample rates of digital control systems (higher sample rates are required). In addition, this form of direct torque control is not suitable for the addition of a high-frequency carrier signal necessary for the "self-sensing" (sensorless) position estimation technique. This technique enables low- and zero-speed position sensorless operation of the machine. Sensorless operation is desirable to reduce the number of necessary feedback signals and transducers, thus improving the reliability and reducing the mass and volume of the system. This research was directed at developing an alternative form of direct torque control known as a "deadbeat," or inverse model, solution. This form uses pulse-width modulation of the voltage applied to the machine, thus reducing the necessary sample and switching frequency for the high-speed NASA motor. In addition, the structure of the deadbeat form allows the addition of the high-frequency carrier signal so that low- and zero-speed sensorless operation is possible. The new deadbeat solution is based on using the stator and rotor flux as state variables. This choice of state variables leads to a simple graphical representation of the solution as the intersection of a constant torque line with a constant stator flux circle. Previous solutions have been expressed only in complex mathematical terms without a method to clearly visualize the solution. The graphical technique allows a more insightful understanding of the operation of the machine under various conditions.
    Keywords: Mechanical Engineering
    Type: Research and Technology 2002; NASA/TM-2003-211990
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  • 5
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    A Flywheel Energy Storage System Demonstration for Space Applications (2003)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A novel control algorithm for the charge and discharge modes of operation of a flywheel energy storage system for space applications is presented. The motor control portion of the algorithm uses sensorless field oriented control with position and speed estimates determined from a signal injection technique at low speeds and a back EMF technique at higher speeds. The charge and discharge portion of the algorithm use command feed-forward and disturbance decoupling, respectively, to achieve fast response with low gains. Simulation and experimental results are presented.
    Keywords: Energy Production and Conversion
    Type: NASA/TM-2003-212346 , E-13934 , NAS 1.15:212346 , International Electric Machines and Drives Conference; Jun 01, 2003 - Jun 04, 2003; Madison, WI; United States
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  • 6
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    Stator and Rotor Flux Based Deadbeat Direct Torque Control of Induction Machines (2002)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A new, deadbeat type of direct torque control is proposed, analyzed, and experimentally verified in this paper. The control is based on stator and rotor flux as state variables. This choice of state variables allows a graphical representation which is transparent and insightful. The graphical solution shows the effects of realistic considerations such as voltage and current limits. A position and speed sensorless implementation of the control, based on the self-sensing signal injection technique, is also demonstrated experimentally for low speed operation. The paper first develops the new, deadbeat DTC methodology and graphical representation of the new algorithm. It then evaluates feasibility via simulation and experimentally demonstrates performance of the new method with a laboratory prototype including the sensorless methods.
    Keywords: Electronics and Electrical Engineering
    Type: NASA/TM-2001-211100/REV1 , NAS 1.15:211100/REV1 , E-12945-1/REV1 , 2001 Industry Applications Society Annual Meeting; Sep 30, 2001 - Oct 05, 2001; Chicago, IL; United States
    Format: application/pdf
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  • 7
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    Flux-Based Deadbeat Control of Induction-Motor Torque (2003)
    In:  CASI
    Details
    Publication Date: 2019-07-12
    Description: An improved method and prior methods of deadbeat direct torque control involve the use of pulse-width modulation (PWM) of applied voltages. The prior methods are based on the use of stator flux and stator current as state variables, leading to mathematical solutions of control equations in forms that do not lend themselves to clear visualization of solution spaces. In contrast, the use of rotor and stator fluxes as the state variables in the present improved method lends itself to graphical representations that aid in understanding possible solutions under various operating conditions. In addition, the present improved method incorporates the superposition of high-frequency carrier signals for use in a motor-self-sensing technique for estimating the rotor shaft angle at any speed (including low or even zero speed) without need for additional shaft-angle-measuring sensors.
    Keywords: Man/System Technology and Life Support
    Type: LEW-17329 , NASA Tech Briefs, April 2003; 22
    Format: application/pdf
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  • 8
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    Control of a High Speed Flywheel System for Energy Storage in Space Applications (2004)
    In:  CASI
    Details
    Publication Date: 2019-07-11
    Description: A novel control algorithm for the charge and discharge modes of operation of a flywheel energy storage system for space applications is presented. The motor control portion of the algorithm uses sensorless field oriented control with position and speed estimates determined from a signal injection technique at low speeds and a back EMF technique at higher speeds. The charge and discharge portion of the algorithm use command feed-forward and disturbance decoupling, respectively, to achieve fast response with low gains. Simulation and experimental results are presented demonstrating the successful operation of the flywheel control up to the rated speed of 60,000 rpm.
    Keywords: Spacecraft Propulsion and Power
    Type: NASA/TM-2004-213356 , E-14824
    Format: application/pdf
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  • 9
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    DC Bus Regulation with a Flywheel Energy Storage System (2003)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This paper describes the DC bus regulation control algorithm for the NASA flywheel energy storage system during charge, charge reduction and discharge modes of operation. The algorithm was experimentally verified with results given in a previous paper. This paper presents the necessary models for simulation with detailed block diagrams of the controller algorithm. It is shown that the flywheel system and the controller can be modeled in three levels of detail depending on the type of analysis required. The three models are explained and then compared using simulation results.
    Keywords: Energy Production and Conversion
    Type: NASA/TM-2002-211897/REV1 , NAS 1.15:211897/REV1 , E-13579-1/REV1 , Rept-02PSC-61/REV1 , Power Systems Conference; Oct 29, 2002 - Oct 31, 2002; Coral Springs, FL; United States
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  • 10
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    Sensorless Control of Permanent Magnet Machine for NASA Flywheel Technology Development (2002)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: This paper describes the position sensorless algorithms presently used in the motor control for the NASA "in-house" development work of the flywheel energy storage system. At zero and low speeds a signal injection technique, the self-sensing method, is used to determine rotor position. At higher speeds, an open loop estimate of the back EMF of the machine is made to determine the rotor position. At start up, the rotor is set to a known position by commanding dc into one of the phase windings. Experimental results up to 52,000 rpm are presented.
    Keywords: Energy Production and Conversion
    Type: NASA/TM-2002-211726 , E-13477 , NAS 1.15:211726 , IECEC-2002-20072 , 37th Intersociety Energy Conversion Engineering Conference; Jul 28, 2002 - Aug 02, 2002; Washington, DC; United States
    Format: application/pdf
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