An integrated permanent magnet Micro-turbo- generator supported on microball bearings
Beyaz, Mustafa İlker
Hanrahan, Brendan M.
Feldman, Jeremy H.
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This paper presents the design, fabrication, and testing of an integrated microturbogenerator utilizing permanent magnets and microball bearings. The key components of this generator are the following: 1) a silicon microturbine rotor housing thick magnetic components; 2) encapsulated microball bearings providing a simple actuation scheme and a robust support structure; and 3) wafer-thick stator coils. The microturbogenerator was designed and fabricated to have a ten-pole rotor and a ten-pole three-turns-per-pole stator. The impedance of the stator coils was shown to be a purely resistive 220 Ω up to 10 kHz. The spin-down characterization of the rotor revealed a dynamic friction torque of 33 μN · m at a rotational speed of 16 kilo rotations per minute (krpm), corresponding to 6% turbine efficiency. The maximum per-phase ac open-circuit voltage and power were measured to be 0.1 V and 5.6 μW on a matched load at 23 krpm, respectively, in full agreement with theoretical analysis and performance estimations. The microturbogenerator presented in this paper provides a flexible design platform for further improvement and will lead to the development of next-generation integrated micro turbogenerators offering high power, simple operation, and robust mechanics.