1 research outputs found
Power Processing for Electrostatic Microgenerators
Microgenerators are electro-mechanical devices which harvest energy from local environmental
from such sources as light, heat and vibrations. These devices are used to
extend the life-time of wireless sensor network nodes. Vibration-based microgenerators
for biomedical applications are investigated in this thesis.
In order to optimise the microgenerator system design, a combined electro-mechanical
system simulation model of the complete system is required. In this work, a simulation
toolkit (known as ICES) has been developed utilising SPICE. The objective is to
accurately model end-to-end microgenerator systems. Case-study simulations of electromagnetic
and electrostatic microgenerator systems are presented to verify the operation
of the toolkit models. Custom semiconductor devices, previously designed for microgenerator
use, have also been modelled so that system design and optimisation of complete
microgenerator can be accomplished.
An analytical framework has been developed to estimate the maximum system effectiveness
of an electrostatic microgenerator operating in constant-charge and constant-voltage
modes. The calculated system effectiveness values are plotted with respect to microgenerator
sizes for different input excitations. Trends in effectiveness are identified and
discussed in detail. It was found that when the electrostatic transducer is interfaced with
power processing circuit, the parasitic elements of the circuit are reducing the energy generation
ability of the transducer by sharing the charge during separation of the capacitor
plates. Also, found that in constant-voltage mode the electrostatic microgenerator has a
better effectiveness over a large operating range than constant-charge devices. The ICES
toolkit was used to perform time-domain simulation of a range of operating points and
the simulation results provide verification of the analytical results