A Self-Excited MEMS Electro-Quasi-Static Induction Turbine Generator

This paper presents a microfabricated electro-quasi-static (EQS) induction turbine generator that has generated net electric power. A maximum power output of 192 mu W was achieved under driven excitation. We believe that this is the first report of net-electric-power generation by an EQS induction machine of any scale found in the open literature. This paper also presents self-excited operation in which the generator resonates with an inductor and generates power without the use of external active-drive electronics. The generator comprises five silicon layers, fusion-bonded together at 700 degrees C. The stator is a platinum-electrode structure formed on a thick (approximately 20 mu m) recessed oxide island. The rotor is a thin film of lightly doped polysilicon also residing on a 10-mu m-thick oxide island. Carrier depletion in the rotor conductor film limited the performance of the generator. This paper also presents a generalized state-space model for an EQS induction machine that takes into account the machine and its external electronics and parasitics. This model correlates well with measured performance and was used to find the optimal drive conditions for all driven experiments.