A fully-integrated multi-watt permanent-magnet turbine generator

The energy density available from batteries is increasingly becoming a limiting factor in the capabilities of portable electronics. As a result, there is a growing need for compact, high energy density sources. This thesis presents the design, fabrication, and testing of a fully-integrated permanent-magnet turbine generator based on silicon MEMS technology envisioned to replace batteries. The air-driven device, supported on gas bearings, has been experimentally shown to deliver 19 mW to matched resistive loads of 0.33 [omega] while operating at a rotational speed of 40 krpm. With an active volume of 41 mm³, this translates to a power density of 0.46 mW/mm³. By extrapolating the experimental data up to the design speed of 360 krpm, it is expected that the integrated generator can deliver 1.5 W of output power.This research represents the first batch-fabricated permanent-magnet generator shown to generate milliwatt-level power, with a further potential to deliver watt-level power. To achieve full integration, a broad range of topics are examined, including the design of gas bearings, high-speed mechanical analysis using non-ideal material interfaces, magnetic rotor balancing, and novel fabrication techniques.A major challenge unique to the integrated device is the need for both silicon and non-silicon components on the same die. While the silicon components are precision micromachined using DRIE and can withstand high temperatures, the permanent magnets are laser-machined separately and rapidly demagnetize when exposed to heat. Similar problems exist for the copper surface windings. The differences are reconciled with the use of a novel drop-in technique, which involves placing nonsilicon components into the die after all the silicon fabrication is complete.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2008

Author dc:creator

• Yen, Bernard Chih-Hsun, 1981-

Advisor dc:contributor.advisor

• Jeffrey H. Lang and Zoltan S. Spakovszky.

• Electrical Engineering and Computer Science.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/45860

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/45860