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OPS - Energy Harvesting. Name: Alex Phipps 12/13/2005 Goals: Mount solar cells to board. Test PZT with resistive and PRC loads to confirm bimorph models and experimental data. Key accomplishments. Most parts have been soldered onto solar board. - PowerPoint PPT Presentation
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OPS - Energy Harvesting• Name: Alex Phipps 12/13/2005• Goals:
– Mount solar cells to board.– Test PZT with resistive and PRC loads to confirm bimorph models and
experimental data.• Key accomplishments.
– Most parts have been soldered onto solar board.– Shengwen’s files have all been transferred and are functional.
• Key issues – How to attach the solar cells to the board.– PZT bimorph beams no longer have the same impedance when measured.
• Simulations are also difficult because the model doesn’t allow for Ropt to be used.
• Next steps– Populate both boards.– Create test plan for new solar ICs.
• New design has test pins for charge pump.
Action Items
1) Build Charge Pump Board.1) Conduct a literature survey to determine if the charge pump is
publishable.
2) Construct board for solar converter/controller.1) Plan a paper around it.
3) Simulate PZT converter with Shengwen and Anurag to verify 6uW with Bimorph.
4) Simulate resistive loading and compare with experiments.
5) Talk with Erin about gold plating/ Wirebonding from IMG.
6) More solar cells available?
7) Software from Shenwen and familiarize with his work.
Action Item Progress
1) Build Charge Pump Board.1) On hold while solar board is being constructed.
2) Construct board for solar converter/controller.1) Board milled and most components have been added.
3) Simulate PZT converter with Shengwen and Anurag to verify 6uW with Bimorph.1) Simulations predict more than 6uW of power using the Bimorph
model.
4) Simulate resistive loading and compare with experiments.1) Resistive loading seems to have changed for the Bimorph beams
since the first data was taken.
2) Simulations cannot be easily altered to fit experimental results.
Action Item Progress
5) Talk with Erin about gold plating/ Wirebonding from IMG.1) Probably will not be able to do it. Most likely will hire Al Ogden to
complete the wirebonding.
6) More solar cells available?1) IXYS has not responded to either of my emails. I also phoned in
with little luck.
7) Software from Shenwen and familiarize with his work.1) PZT and solar simulations finally both work on my account and
backups are made.
Wirebonding
• Al Ogden will probably have to do this.– Other options:
• Gold plate whole board. – Cost and still need to wirebond.
• Get gold plating “pen system”– Requires time to get system and cost of pens.
– It will cost ~$52/hr and Al estimated 2-3hrs to do the whole job.– There is also the cost of silver epoxy, which should be relatively
cheap.
PZT Testing
• PZT tests conducted by Shengwen show the following:
Pmax Propt
R = 15.84k
Pp.r.
Calculated 34.3u 32.9u 9.65u
Simulated
(in cadence)
34.1u 32.7u 9.86u
Measured N/A 13u 6u
PZT Testing
• The problem for the PZT is now this:– The model that Anurag has for the bimorph gives a Ropt = 15.84k. Using
this model in the cadence simulation with Ropt = 15.84k, resulted in an output of 32.7uW. When the bimorph beam was physically tested, the Ropt = 50k, and the maximum power output was only 13uW.
– It is possible that the R1 measured to make the LEM model of the bimorph had some error. Since R1 is a major component in Re’, this could have a big effect on the Ropt. We want to edit Re’ so that Ropt is now equal to 50k. This means:
– And since:
optTH RZ
eeb
eTH RCj
RZ
1
PZT Testing
– We know that we must just change Re so that the impedance |ZTH| is 50k. However, due to the capacitance value that we found this is impossible.
• The measured Ropt was done rather roughly, so Anurag and I decided to re-measure.– We found that Ropt had changed for the bimorphs and that the
maximum power was no longer as high as it had been.• This will require more investigation.