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Thesis (M.Eng. and S.B.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2002., Includes bibliographical references (leaf 125)., by Sauparna Das., M.Eng.and S.B.

This paper presents the design, fabrication, and characterization of laminated, magnetic induction machines intended for high-speed, high-temperature, high-power-density, silicon-based microengine power generation systems. Innovative fabrication techniques were used to embed electroplated materials (Cu, Ni80Fe20, Co65Fe18Ni17) within bulk-micromachined and fusion-bonded silicon to form the machine structures. The induction machines were characterized in motoring mode using tethered rotors, and exhibited a maximum measured torque of 2.5 microNu m., Pub. in the Journal of Microelectromechanical Systems, v15 n2, p405-414, Apr 2006.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005., Includes bibliographical references (p. 321-323)., This thesis presents the modeling, design, and characterization of microfabricated, surface-wound, permanent-magnet (PM) generators, and their power electronics, for use in Watt-level Power MEMS applications such as a microscale gas turbine engine. The generators are three-phase, axial-flux, synchronous machines, comprising a rotor with an annular PM and ferromagnetic core, and a stator with multi-turn surface windings on a soft magnetic substrate. The fabrication of the PM generators, as well as the development of their high-speed spinning rotor test stand, was carried out by collaborators at the Georgia Institute of Technology. The machines are modeled by analytically solving 2D magneto-quasistatic Maxwell's Equations as a function of radius and then integrating the field solutions over the radial span of the machine to determine the open-circuit voltage, torque and losses in the stator core. The model provides a computationally fast method to determine power and efficiency of an axial-air-gap PM machine as a function of geometry, speed and material properties. Both passive and active power electronics have been built and tested. The passive power electronics consist of a three-phase transformer and diode bridge rectifier., (cont.) The active power electronics consist of a switch-mode rectifier based on the boost semi-bridge topology which is used to convert the unregulated AC generator voltages to a regulated 12 V DC without the need for rotor position/speed or stator terminal current/voltage sensing. At the rotational speed of 300,000 rpm, one generator converts 16.2 W of mechanical power to electrical power. Coupled to the transformer and diode bridge rectifier, it delivers 8 W DC to a resistive load. This is the highest output power ever delivered by a microscale electric generator to date. The corresponding power and current densities of 57.8 MW/m3 and 6x 108 A/m2, respectively, are much higher than those of a macroscale electric generator. At the rotational speed of 300,000 rpm, the generator and switch-mode rectifier delivered 5.5 W DC to a resistive load at a power density three times that of the passive electronics. This Watt-scale electrical power generation demonstrates the viability of scaled PM machines and power electronics for practical Power MEMS applications., by Sauparna Das., Ph.D.

This paper reports the high-speed experimental characterization of a microscale, axial-flux, permanentmagnet (PM) generator to failure. A single-phase, opencircuit voltage of 0.9 Vrms was measured at 225 krpm, which corresponds to 3.3 W of DC power if the machine were connected via power electronics to a matched resistive load. Finite-element analysis was used to model and examine the mechanical design of the high-speed rotor assembly to increase the speed and, hence, output power of the device. Ultimately, rotor speeds of 325 krpm were achieved using a titanium rotor housing., The original document contains color images.

This paper presents the design, fabrication, and characterization of laminated, magnetic induction machines intended for high-speed, high-temperature, high-power-density microengine power generation systems. Innovative fabrication techniques were used to embed electroplated materials (Cu, Ni80Fe20, Co65Fe18Ni17) within etched and fusion-bonded silicon to form the machine structure. The induction machines were characterized in motoring mode using tethered rotors, and exhibited a maximum measured torque of 2.5 N m and a projected torque density of 340 N-m/m3.

This paper presents recent advances in the development of a micro magnetic induction motor/generator. The development of this machine is part of an ongoing project to develop high-power-density electric machinery for use in portable power applications. The results reported here focus on testing a first-generation non-laminated tethered motor, and fabricating a second-generation laminated tethered motor. These tethered motors are metrology devices designed for exploring and characterizing the fabrication and operating behavior of the micro magnetic induction machine.