Search NASA⌕ Search

Engineering topics

Kirk, James A.

Publications and source records attributed to Kirk, James A..

12 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

High efficiency magnetic bearings

Research activities concerning high efficiency permanent magnet plus electromagnet (PM/EM) pancake magnetic bearings at the University of Maryland are reported. A description of the construction and working of the magnetic bearing is provided. Next, parameters needed to describe the bearing are explained. Then, methods developed for the design and testing of magnetic bearings are summarized. Finally, a new magnetic bearing which allows active torque control in the off axes directions is discussed.

Studer, Philip A.↗
NASA NTRS1992

Development of a differentially balanced magnetic bearing and control system for use with a flywheel energy storage system

The purpose of a magnetically suspended flywheel energy storage system for electric utility load leveling is to provide a means to store energy during times when energy is inexpensive to produce and then return it to the customer during times of peak power demand when generated energy is most expensive. The design of a 20 kWh flywheel energy storage system for electric utility load leveling applications involves the successful integration of a number of advanced technologies so as to minimize the size and cost of the system without affecting its efficiency and reliability. The flywheel energy storage system uses a carbon epoxy flywheel, two specially designed low loss magnetic bearings, a high efficiency motor generator, and a 60 cycle AC power converter all integrated through a microprocessor controller. The basic design is discussed of each of the components that is used in the energy storage design.

Higgins, Mark A.↗
NASA NTRS1991

Development of a high-efficiency motor/generator for flywheel energy storage

This study addresses the design changes and extensions necessary to construct and test a working prototype of a motor/generator for a magnetically suspended flywheel energy storage system. The brushless motor controller for the motor was specified and the electronic commutation arrangement designed. The laminations were redesigned and fabricated using laser machining. Flux density measurements were made and the results used to redesign the armature windings. A test rig was designed and built, and the motor/generator was installed and speed tested to 9000 rpm. Experimental methods of obtaining the machine voltage and torque constants Kv and Kt, obtaining the useful air-gap flux density, and characterizing the motor and other system components are described. The measured Kv and Kt were approximately 40 percent greater than predicted by theory and initial experiment.

Lashley, Christopher↗
NASA NTRS1988

System characterization of a magnetically suspended flywheel

The purpose of flywheel energy storage is to provide a means to save energy during times when the satellite is in sunlight, and then return the energy during the time when the satellite is in darkness. Typically, an energy storage device operates cyclically, where for satellites in Low Earth Orbit (LEO) the typical period is 60 minutes of sunlight followed by 30 minutes of darkness. If a lifetime of 17 years is required the energy storage system must be capable of sustaining approximately 100,000 cycles. The recent developments at the University of Maryland and how these progressions apply to a 500 Watt-hour magnetically suspended flywheel stack energy storage system are covered. The work includes hardware testing results from a stack flywheel energy storage system, improvements in the area of non-contacting displacement transducers, and performance enhancements of magnetic bearings. The experimental results show that a stack flywheel energy storage system is a feasible technology.

Kirk, James A.↗
NASA NTRS1988

Satellite power using a magnetically suspended flywheel stack

Research activities with magnetically suspended flywheels are reported. The purpose of the effort is to critically examine and further the development of all the key technologies which impact the inertial energy storage system. The results presented discuss the concept of a magnetically suspended flywheel as it applies to a 500 Watt-hour energy storage system. The proposed system is currently under hardware development and is based upon two pancake magnetic bearings arranged in a vertical stack.

Kirk, James A.↗
NASA NTRS1988

Overview of a flywheel stack energy storage system

The concept of storing electrical energy in rotating flywheels provides an attractive substitute to batteries. To realize these advantages the critical technologies of rotor design, composite materials, magnetic suspension, and high efficiency motor/generators are reviewed in this paper. The magnetically suspended flywheel energy storage system, currently under development at the University of Maryland, consisting of a family of interference assembled rings, is presented as an integrated solution for energy storage.

Kirk, James A.↗
NASA NTRS1988

The effect of rotor dynamics on a flywheel stack energy storage system

The paper presents a dynamic analysis of a magnetic-bearing stack system consisting of a single flywheel supported by two magnetic bearings. Real-time plots from a computer simulation are used to show the effect of dynamic coupling on the torque response, and the frequency response is used to determine the resonance frequencies of the stack system. It is found that system stability depends on the flywheel speed.

Jayaraman, Chaitanya P.↗
NASA NTRS1988

Improvements in magnetic bearing performance for flywheel energy storage

The paper considers the development of a 500-Watt-hour magnetically suspended flywheel stack energy storage system. The work includes hardware testing results from a stack flywheel energy storage system, improvements in the area of noncontacting displacement transducers, and performance enhancements of magnetic bearings. Experimental results show that a stack flywheel energy storage system is feasible technology.

Plant, David P.↗
NASA NTRS1987

Satellite power using magnetically suspended flywheel stack

Research activities with magnetically suspended flywheels are reported. The purpose of the effort is to critically examine and further the development of all the key technologies which impact the inertial energy storage system. The results presented discuss the concept of a magnetically suspended flywheel as it applies to a 500 Watt-hour energy storage system. The proposed system is currently under hardware development and is based upon two pancake magnetic bearings arranged in a vertical stack.

Kirk, James A.↗
NASA NTRS1987

Magnetically suspended stacks for inertial energy storage flywheel

A magnetically suspended flywheel stack based on a 'pancake' magnetic bearing stack is proposed for a 500 watt-hour energy storage system. Backup ball bearings in the system configuration both prevent damage to the system whenever there is a loss of magnetic suspension due to excessive outside disturbances, and insure that the fywheel stays within the linear control range. Design tools to investigate the performance of the control system and the magnetic circuits are also discussed.

Anand, Davinder K.↗
NASA NTRS1987

Dynamic response of a magnetically suspended flywheel with mass unbalance

The forced translational and rotational motion of a magnetically suspended flywheel due to mass unbalance is investigated. It is found that a magnetically suspended flywheel can tolerate greater mass unbalance than a conventional rotor system because in a magnetic suspension system, vibration and the transmission of dynamic loads are eliminated in the absence of mechanical contact. It is shown that although vibration and dynamic loads are not transmitted between the rotor and stator of a magnetically suspended flywheel, inertial forces and moments due to mass unbalance are generated when the flywheel is spinning. Numerical results demonstrate that the inertial forces and moments cause the flywheel to tilt and to displace radially from its centered position.

Wong, Kenneth↗
NASA NTRS1987

Prototype testing of magnetic bearings

The testing and evaluation of the performance of a magnetic bearing assembly for flywheel energy storage applications are discussed. The experimental set up for determining the passive radial stiffness, active radial stiffness, and curent force sensitivity of the coils follows the method developed by Frommer (1986). Magnetic bearings design should preclude saturation and current limiting in the desired operating range, so that the system will be linear. A larger linear range will lead to a more stable magnetic bearing.

Plant, David P.↗