who is expert in piezoelectric

i doing my fyp using piezoelectric

i found many difficulty in doing this piezoelectric

does anyone of you is expert in piezoelectirc?

Morgan Electroceramics have a very good 'book' on piezos you can download from their web site. I have used piezos quite a bit, from edrums to ultrasonic cleaners to underwater communications. What specific questions do you have (apart from which diode to use ?

Keith

keith1200rs said:

Morgan Electroceramics have a very good 'book' on piezos you can download from their web site. I have used piezos quite a bit, from edrums to ultrasonic cleaners to underwater communications. What specific questions do you have (apart from which diode to use ?

Keith

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thanks keith, you really help me a lot

keith, do you mind to criticize my design circuit?


i try to build a energy harvesting circuit from some material capable to generated electric when applied mechanical force such as piezo.

despite all value in the circuit.

can my circuit work with this schematic design?

1. V1 is the input source act as the piezo **(ignored the value of V1)
2. V1 connect to schottky diode D3,D4,D5,D6 act as rectifier.
3. rectifier connect to capacitor, C1 is used to stored the amount of energy
4. D7 and D8 are zener diode is used to voltage regulator
5. c3 is used to stored the energy

please see the attachment

thank you very much, your helps will deeply appreciated

Piezos can give out a DC or AC signal depending on how they are used. Normally you get an AC signal from the natural resonance of the crystal. So, if you hit it then the output is an oscillation which decays. If there is a lot of mechanical damping on the crystal then it will damp the oscillations quicker. Electrically loading the piezo can also damp the oscillations.

If you mechanically damp the crystal enough you can get just a single pulse, either positive or negative depending on how you connect the crystal. This is really a heavily damped ringing - so well damped that you only get half a sine wave of ringing.

For harvesting the energy I would be tempted to use a different circuit. There are some energy harvesting ICs around which would be worth looking at.

The best circuit depends on the voltage you are getting from the piezo. If it is a small voltage then a single diode may be better. While a full wave bridge theoretically captures both halves of an AC signal it will lose 2 diode volts drops instead of one. You need to experiment to see which works best. You really need to be looking at the piezo pulses on an oscilloscope.

After the diode I would then use a capacitor as you have, but then a DC-DC converter, maybe a SEPIC/buck-boost type, to charge the main storage capacitor.

Keith

Added after 2 hours 35 minutes:

It may not be the right device for a piezo, but look at the LTC3108 from Linear Technology and similar devices.

Keith

If you mechanically damp the crystal enough you can get just a single pulse, either positive or negative depending on how you connect the crystal. This is really a heavily damped ringing - so well damped that you only get half a sine wave of ringing.

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its this mean the output from piezoelectric is DC if we mechanically damp the crystal?

yes, there are some IC is worth to looking at, but then the price is not cheap, since we can build our own simply energy harvesting circuit. energy harvesting LTC3588-1 - Piezoelectric Energy Harvesting Power Supply IC is very good. but........ money!

your suggestion is to use only 1 diode and then connect to the capacitor and used DC-DC converter to charge the main storage.

The advantage of the DC-DC converters designed for the job is they have very low quiescent currents and low voltage drop bridge rectifier. So, you need to experiment, particularly if you don't know the nature of the piezo signals.

If you sufficiently damp a piezo signal you can get a half cycle "DC" signal.

I would start off with a diode or bridge using Schottky diodes & DC-DC converter. The LTC3588 uses a buck converter, so it is assuming a piezo voltage always above the output voltage. Again, that would seem a reasonable way to start until you can collect some data from your own system.

Keith.

Hi Study,
You can build your self the converter, but dont forget pls, that a piezo harvester delivers in some 10uW level_only if dont have a strong rezonance on a vibrating mashine...
K.
TPS61200 is a Harvesting dedicated DC/DC Converter too & price is at $ 2-3,-, than similar is a "self resonating design operates from 20mV_especially with TEGs" LTC3108 $ 6,50--8,-- ...https://octopart.com

Hi,
A some actual (from yesterday ) news: Vibration harvesters designed to replace AA, AAA batteries_Brother,Japan
http://www.power-eetimes.com/en/vib...eries.html?cmp_id=7&news_id=222901222&vID=160
K.

keith1200rs said:

The advantage of the DC-DC converters designed for the job is they have very low quiescent currents and low voltage drop bridge rectifier. So, you need to experiment, particularly if you don't know the nature of the piezo signals.

If you sufficiently damp a piezo signal you can get a half cycle "DC" signal.

I would start off with a diode or bridge using Schottky diodes & DC-DC converter. The LTC3588 uses a buck converter, so it is assuming a piezo voltage always above the output voltage. Again, that would seem a reasonable way to start until you can collect some data from your own system.

Keith.

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thank keith, agains your information and guidance is very useful for me.

there is one problem if i use the DC-DC converter either is buck or boost converter, its required a switch mostly like using mosfet. my circuit doesnt have any voltage to turn on the switch, all my circuit is passive component.

is there any way to implement the DC-DC converter?

Hi,
Nothing is coming from nothing on these world...
Read pls some from energy harvesting/scaving literature, self LT; TI and such others as EnOcean... have good library/scripts,
but as need some time & nerv to search for that
K....

studystudystudy said:

there is one problem if i use the DC-DC converter either is buck or boost converter, its required a switch mostly like using mosfet. my circuit doesnt have any voltage to turn on the switch, all my circuit is passive component.

is there any way to implement the DC-DC converter?

Click to expand...

You are not doing trivial design here, but the way that problem is usually solved is by bootstrapping. You do need enough voltage to turn on the MOSFET to begin with then you add a circuit to provide voltage to the MOSFET drive back from your reservoir capacitor.

I think you should start with a simple diode and capacitor and try to get some results first. Then you can decide what you need to do to improve it.

Keith.

Exactly, as you tells Keith,
@studystudystudy
To beginn is to have/take an energy spectrum of the existent vibration & so is to design what is possible to make, otherwise can be for ever only a dream :-( to harvesting some power (from practically nothing) & drive some electronics with the (theoratically) collected energy...
Anyways, be care pls, as I told, than piezo delivers only in range (tenth)of microwatts for you.
K.

thanks keith and karesz,

yes, tomoro i will go to try the circuit using oscilloscope and get some data from it.

i will try use the simple diode and capacitor and try to get some results first

thanks again keith and karesz

tnx & good luck!
(dont forget to use pls some R as load too )
K.

hi study and Mr.keith ,we are also trying to harvest energy from keyboard stress using piezoelectric principle.can we use single electron transistor(SET) as an amplifier for this.