Table of Contents
Feasibility / Engineering AnalysisThe power for the system will be taken from the a thermoelectric module. The output voltage and current from the TEG change with load that is attached to the TEG. To obtain maximum power from the TEG a load that is equivalent to the internal electrical resistance must be attached. This internal electrical resistance changes with temperature, because of this an MPPT must be implemented. A paper on the use of analog controls of an MPPT can be downloaded here. This paper formed the corner stone of the operation of the maximum power point tracker.
Testing was performed on the TEG unit to determine the amount of power that would be available at steady state from the TEG. This is required to determine if there would be enough power to do what we need to do. The test data can be seen here. This data was used to predict the transiant behavior of the TEG as it heats up. The voltage-current curves of the TEG were predicted using that data and the results can be seen here.
The next step is converting the output of the MPPT into usable voltages and currents. Switch converters have been in use since the 50's and provide high efficiency at a range of input and output voltages and currents. The prefabricated IC's were ideal for these reasons and their low cost. A brief overview of switching converters can be found here.
SimulationsThe pspice simulations for the MPPT can be viewed here.
The pSpice simulations for the USB converter can be seen here.
The part selected for the fan converter do not have a pSpice model, due to the proprietary nature of the component creating our own was impossible. However the technology being implemented was proven and no simulation was required to ensure proper operation.
The pSpice simulations for the high and low voltage disconnect systems can be seen here.
SchematicsThe schematic of the working prototype can be viewed here.
The bill of materials can be viewed here.
Test PlansThe test conditions for the electrical systems can be found here.
The test conditions for the mechanical system can be found here.
More detailed test procedures can be found in the Build, Test, Document section.