Energy storage is becoming increasingly important with the rising need to accommodate the energy needs of a greater population. Energy storage is especially important with intermittent sources such as solar and wind. Flywheel energy storage systems store kinetic energy by constantly spinning a compact rotor in a low-friction environment. When short-term back-up power is required as a result of utility power loss or fluctua tions, the rotor's inertia allows it to continue spinning and the resulting kinetic energy is converted to electricity. Unlike fossil-fuel power plants and batteries, the flywheel based energy storage systems do not emit any harmful byproducts during their operation and have attracted interest recently. A typical flywheel system is comprised of an energy stor age rotor, a motor-generator system, bearings, power electronics, controls, and a con tainment housing. Conventional outer flywheel designs have a large diameter energy storage rotor attached to a smaller diameter section which is used as a motor!generator. The cost to build and maintain such a system can be substantial. This paper presents a unique concept design for a / kW-li inside-out integrated flywheel energy storage system.The flywheel operates at a nominal speed o f40,000 rpm. This design can potentially scale up for higher energy storage capacity. It uses a single composite rotor to peiform the functions o f energy storage. The flywheel design incorporates a five-axis active magnetic bearing system. The flywheel is also encased in a double layered housing to ensure safe operation. Insulated-gate bipolar transistor (IBGT) based power electronics are adopted as well. The design targets cost savings from reduced material and manufacturing costs. This paper focuses on the rotor design, the active magnetic bearing design, the associated rotordynamics, and a preliminary closed-loop controller.

The progress in the development of ventricular assist artificial heart pumps is continuing. This paper describes the magnetic suspension for a unique prototype axial flow pump designed for approximately 6 L/min at 100 mm Hg performance with an operating speed of approximately 7,000 rpm. The integrated magnetic suspension design provides a direct non-contact blood flow path through the pump with no obstructions which might create low flow areas and thrombosis (blood clots). The magnetic suspension is a combination of permanent magnets (PMs) and active magnetic bearings (AMBs). There are two radial AMBs which support the four degrees of freedom at the ends of the axial pump impeller and an axial PM thrust bearing. The axial PM bearing supports the direction of the largest fluid force on the impeller. A major objective of artificial hearts is to have extremely low power consumption. Thus the integrated PM and AMB suspension system has an operating magnetic suspension power of approximately 2 watts. The design, numerical modeling, and testing of the magnetic suspension system to support the fluid loads and the g loads are described in the paper.

Machinery and Controls Laboratory (ROMAC). The technical and social experiences that I have gained under his guidance will last a lifetime. I am thankful to Dr. Timothy Dimond for his fullfledged support and guidance throughout my time in ROMAC. I am especially thankful for his advising and mentoring at a very difficult time. This thesis would have not been made possible without both Prof. Allaire and Dr. Dimond. I would also like to mention my thesis committee Prof. Houston Wood, Prof. George Gillies, Prof. Andre Clarens and Dr. Wei Jiang for providing me with their valuable insights to shape up this thesis. I would like to thank all my colleagues who helped me shape up this thesis. I would like to specially mention Mr. Jason Kaplan for his time in helping me with the ROMAC codes and Mr. Parinya Ananthachaisilp for his enthusiasm and patience in helping me understand the controller design. I shall always be indebted to my family for their constant support and encouragement during this time period. I would like to thank my wife, Subhashini Vel, for being there for me whenever I needed help or a shoulder. I am thankful to my parents, Muthaiyan Kailasan and Thangamani Kailasan, for showing me the right path when in doubt. I would also like to thank my sister, Dr. Kruthikaveni Kailasan, and my brother in law, Dr. Vinodh kumar, for being a pillar of strength and support. Special thanks to my nephew, Vishaal Vinodhkumar, for helping me balance work and play. I would like to end my note by mentioning that my graduate life at ROMAC and UVA has provided me with the necessary tools to succeed in my career and more importantly, to succeed as a human being.

Energy storage is becoming increasingly important with the rising need to accommodate the energy needs of a greater population. Energy storage is especially important with intermittent sources such as solar and wind. Flywheel energy storage systems store kinetic energy by constantly spinning a compact rotor in a low-friction environment. When short-term back-up power is required as a result of utility power loss or fluctuations, the rotor’s inertia allows it to continue spinning and the resulting kinetic energy is converted to electricity. Unlike fossil-fuel power plants and batteries, the flywheel based energy storage systems do not emit any harmful byproducts during their operation and have attracted interest recently. A typical flywheel system is comprised of an energy storage rotor, a motor-generator system, bearings, power electronics, controls and a containment housing. Conventional outer flywheel designs have a large diameter energy storage rotor attached to a smaller diameter section which is used as a motor/generator. The cost to build and maintain such a system can be substantial. This paper presents a unique concept design for a 1 kW-hr inside-out integrated flywheel energy storage system. The flywheel operates at a nominal speed of 40,000 rpm. This design can potentially scaled up for higher energy storage capacity. It uses a single composite rotor to perform the functions of energy storage. The flywheel design incoporates a 5-axis active magnetic bearing system. The flywheel is also encased in a double layered housing to ensure safe operation. IGBT based power electronics are adopted as well. The design targets cost savings from reduced material and manufacturing costs. This paper focuses on the rotor design, the active magnetic bearing design, the associated rotordynamics and a preliminary closed-loop controller.

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