Author Topic: Piezoelectric sensors - Energy harvasting  (Read 436 times)

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Offline Nikos A.

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Piezoelectric sensors - Energy harvasting
« on: January 16, 2020, 06:30:04 pm »
Hi everyone, I am designing a smast insole and I want to include energy harvasting from piezoelectric sensors (probably PZTs) as an auxiliary charging system. I want to ask if anyone has experience with piezo energy harvesting and how should I connect the sensors (I am not sure for the quantity) with the ic ( I am looking for the BQ25505 of Texas Instrumenrs)

Thanks in advance
Nick
 

Offline moffy

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Re: Piezoelectric sensors - Energy harvasting
« Reply #1 on: January 17, 2020, 11:00:40 am »
Where are you getting your PZT material from? I looked a while back and found it hard to source at a reasonable price.
 

Offline Nikos A.

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Offline Conrad Hoffman

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Re: Piezoelectric sensors - Energy harvasting
« Reply #3 on: January 17, 2020, 06:04:01 pm »
PZTs are great at generating impressive voltages into high impedance loads, but absolutely terrible at energy conversion. IOW, they don't produce much actual power. Expect charging anything useful to take a very long time.
 

Offline Twoflower

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Re: Piezoelectric sensors - Energy harvasting
« Reply #4 on: January 17, 2020, 07:03:45 pm »
In a newspaper I found a link to some commercial products: https://piezo.com/collections/piezoelectric-energy-harvesters?_=pf&pf_t_quantity=Quantity__1

Not really cheap as it looks like. Especially if you check the output power: 26mW for $60.
 

Offline moffy

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Re: Piezoelectric sensors - Energy harvasting
« Reply #5 on: January 18, 2020, 06:28:33 am »
The amazon PZT's appear quite reasonable. Pity they are only round.
 

Offline Nikos A.

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Re: Piezoelectric sensors - Energy harvasting
« Reply #6 on: January 18, 2020, 11:10:00 am »
I am trying to figure out how to connect/combine the piezoelectric sensors since the output voltage of each one would not be the same ( it is proportional to the applied pressure and since they are intented for insole application the output of each one will differ according to the pressure applied by the foot)

Any help?
 

Online Marco

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Re: Piezoelectric sensors - Energy harvasting
« Reply #7 on: January 18, 2020, 10:00:39 pm »
Wouldn't dielectric elastomers be much better for energy harvesting in a sole? (ie. a charged capacitor with a compressible dielectric.)
 

Offline Nikos A.

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Re: Piezoelectric sensors - Energy harvasting
« Reply #8 on: January 18, 2020, 11:15:57 pm »
Maybe.. I do not know how this technology works but at the moment I want to proceed with piezoelectric..
 

Offline Conrad Hoffman

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Re: Piezoelectric sensors - Energy harvasting
« Reply #9 on: Yesterday at 04:41:38 am »
If you distribute them it's almost certain they will be working at cross purposes. No doubt one could use diodes to steer the charge, with the associated losses of course. I'd find one location that moves in a predictable fashion and put the device(s) there. Not sure if it's best to go parallel or series.
 

Online Marco

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Re: Piezoelectric sensors - Energy harvasting
« Reply #10 on: Yesterday at 02:56:24 pm »
You should probably prestress the piezo discs, they are meant to bend like this along the entire edge of the disc, not compress or bend along just one axis.

So put a tiny bit of rubber in between two discs and then clamp/glue the edges together. That way when you compress the rubber they bend like they are supposed to.
 

Offline soubitos

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Re: Piezoelectric sensors - Energy harvasting
« Reply #11 on: Yesterday at 03:52:46 pm »
 


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