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Abstract--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 "inside-out" 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 non-rotating bearing test fixture was designed and built which permits measurement of static and dynamic force. An active magnetic bearing (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 characteristics. Manuscript

The design and initial testing of a five axis magnetic bearing system in an energy storage flywheel is presented. The flywheel is under development at the University of Texas Center for Electromechanics (UT-CEM) for application in a transit bus. The bearing system for the prototype features homopolar permanent magnet bias magnetic bearings. The system has been successfully tested to the maximum design speed of 42,000 rpm. A gain-scheduled, MIMO control algorithm was required to control the system modes affected by rotor gyroscopics. The implementation and basis for this control scheme is discussed. The cross-axis forces produced by this approach are described in terms of circumferential cross-coupled stiffness and damping to explain the effect on system stability. Dynamic test results are discussed relative to the rotordynamic and control system design.

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This publication details the optimization and baseline design of the discarding metal armature and electromagnetic railgun developed for the U.S. Army Armament Research Development and Engineering Center and U.S. Marine Corps sponsored Cannon Caliber Electromagnetic Launcher program.The primary goals of this program have been to defeat specified targets at 1,500 and 3,000 m range utilizing an electromagnetic launcher system weighing less than 5,000 Ib.An optimization algorithm was developed to integrate the armor-penetrating sub-projectile with a discarding armaturdsabot forming an integrated launch package. This algorithm coupled integrated launch package electromagnetic and structural design requirements to launcher design parameters including rail resistance per unit length and inductance per unit length as a function of launcher rail geometric2 and structural configurations. Pulsed power supply size and mass requirements were subsequently estimated from launcher performance predictions.This study shows that minimizing breech energy required by the launcher will minimize total system mass. A two-turn augmented, rectangular bore barrel, firing a mid-drive discarding armature that launches its subprojectile at 1,850 d s resulted in minimum system mass. The series augmented electromagnetic launcher will be powered by a 4-pole, air-core, compulsator that stores the total launch energy inertially in its composite rotor. This compulsator driven electromagnetic test bed will be capable of accelerating 15 each, 185 g integrated launch packages in three salvos of five shots, with a shot rate of 300 rounds per minute and two seconds between salvos.

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