supercapacitor and mosfet / voltage sensing switch (energy harvesting) considerations

[jeromekang]

are there differences with the supercapacitor position among the setup:
*full bridge rectifier (4 1N60 germanium diodes)
*dc/dc converter (TPS61200)
*supercapacitor (Cellergy 20mF 4.2V Ultracap with ESR = 0.36milliohms)
**full bridge rectifier AND dc/dc converter using LTC3588

a.) piezo/other transducer -> full bridge rectifier -> supercap -> dc/dc -> battery -> load
b.) piezo/other transducer -> full bridge rectifier -> dc/dc -> supercap -> battery -> load
c.) piezo/other transducer -> full bridge rectifier -> dc/dc -> battery -> supercap -> load

in terms of improving the battery life (NiMH) by charging it, what setup would be optimal?

also, what voltage sensing switch can you suggest for energy harvesting applications? what I was thinking of is that when i am able to charge the super capacitor at a certain voltage (like 4v), the voltage sensing switch would close/short then provide power to a circuitry like the dc/dc converter like the TPS61200 or the complete solution harvesting ic LTC3588

 

[andre_luis]

I´m not sure if placing some capacitor close to battery is efective.
The circuit model of the battery is almost the same of the supercap.

Maybe the first configuration ( a ) could be appropriate.

+++

 

[jeromekang]

I´m not sure if placing some capacitor close to battery is efective.
The circuit model of the battery is almost the same of the supercap.

Maybe the first configuration ( a ) could be appropriate.

+++

Thank you andre_teprom, what can you suggest about the voltage sensing switch?

 

[andre_luis]

Jerome,

I didn´t get the purpose of that voltage sensing.
Is it intended to provide a backup power ?

+++

 

[jeromekang]

Jerome,

I didn´t get the purpose of that voltage sensing.
Is it intended to provide a backup power ?

+++

I was thinking of using the voltage sensing switch first as an open switch. When the ultracap charges to a certain voltage (4v), the voltage switch would close shorting the ultracap and the dc/dc regulator. is the voltage sensing switch irrelevant then?

 

[mtwieg]

Rather than having a series switch on the input, you could just enable and disable the regulator based on the input voltage. Should have about the same effect, without a loss in efficiency.

 

[jeromekang]

Rather than having a series switch on the input, you could just enable and disable the regulator based on the input voltage. Should have about the same effect, without a loss in efficiency.

so what i should do is that if i wanted to accumulate the 4v first in the supercapacitor, i should set the UVLO for the dc/dc converter to 4v so that any voltage below 4v, the regulator wouldn't turn on?