This paper presents the physical operating principles of several micro wind turbines based on different aerodynamic forces: drag-type Vertical Axis Wind Turbine (VAWT) and lift-type Horizontal Axis Wind Turbine (HAWT). All these devices share the similarity of exploiting the same mechanical-to-electrical conversion: the electrostatic conversion. This type of conversion is based on capacitance variations induced by the motion between a rotor and a stator and requires a source of polarization. We will focus our study on two technologies to polarize the capacitive structure: the use of electrets and the exploitation of triboelectricity. Some experiments conducted in a low-speed wind tunnel between 0 and 20m.s-1 have highlighted power flux densities from 0 to 150{mu}W.cm-2 corresponding to power coefficients of 0 and 9% respectively. Among these results, we can especially retain an ultralow speed operation, which has never been reached until now, in terms of speed and efficiency (9% of efficiency at 1m.s-1). Finally, we will end up comparing different types of circuits to supply a temperature/acceleration sensor, in order to complete the energy harvesting chain.
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