Description
Date depot: 1 janvier 1900
Titre: Study, optimization and silicon implementation of a smart high-voltage conditioning circuit for electrostatic vibration energy harvesting system
Directeur de thèse:
Alain GREINER (LIP6)
Domaine scientifique: Sciences et technologies de l'information et de la communication
Thématique CNRS : Non defini
Resumé:
Vibration energy harvesting is a relatively new concept that can be used in powering
micro-scale power embedded devices with the energy of vibrations omnipresent in the
surrounding. This thesis contributes to a general study of vibration energy harvesters
(VEHs) employing electrostatic transducers. A typical electrostatic VEH consists of
a capacitive transducer, conditioning electronics and a storage element. This work is
focused on investigations of the reported by MIT in 2006 auto-synchronous conditioning
circuit, which combines the diode-based charge pump and the inductive flyback energy
return driven by the switch. This architecture is very promising since it eliminates
precise gate control of transistors employed in synchronous architectures, while a unique
switch turns on rarely.
This thesis addresses the theoretical analysis of the conditioning circuit. We developed
an algorithm that by proper switching of the flyback allows the optimal energy conversion
strategy taking into account the losses associated with the switching. By adding the
calibration function, the system became adaptive to the fluctuations in the environment.
This study was validated by the behavioral modeling.
Another contribution consists in realization of the proposed algorithm on the circuit
level. The major design difficulties were related to the high-voltage requirement and the
low-power design priority. We designed a high-voltage analog controller of the switch
using AMS035HV technology. Its power consumption varies between several hundreds
nanowatts and a few microwatts, depending on numerous factors - parameters of external
vibrations, voltage levels of the charge pump, frequency of the flyback switching,
frequency of calibration function, etc.
We also implemented on silicon, fabricated and tested a high-voltage switch with a novel
low power level-shifting driver. By mounting on discrete components the charge pump
and flyback circuit and employing the proposed switch, we characterized the wideband
high-voltage operation of the MEMS transducer prototype fabricated alongside this thesis
in ESIEE Paris. When excited with stochastic vibrations having an acceleration level
of 0.8 g rms distributed in the band 110-170 Hz, up to 0.75 μW of net electrical power
has been harvested.
Doctorant.e: Dudka Andrii