Hi all, I am building a piezoelectric energy harvester with compression based piezo material. Do you have any recommendation of energy harvesting circuit for low voltage pulse, small current and low power input source? I found the synchronized switch harvesting on inductor (SSHI) but I don't understand which kind of the electronic switch that used before the diode rectifier. Anyone can help me?
I would suggest adding capacitors in series in the electric circuit to store the low voltage generated from the piezoelectric generator. Adding diode and rectifier would also be recommended. I assume the electronic switch would be the on/ off type.
As a final note for your information, there are other energy harvesting materials that are much better than the piezoelectrics. For example, the ferroelectric polymers are considered to be the most promising electroactive materials.
Hope this helps answer your question.
Professor Yehia Khalil, Yale University, USA
Fellow of the University of Oxford, United Kingdom
By Compression based piezo-materials, I assumed you mean the piezoelectric layers/patches that their 3-1 mode is exploited to generate electrical charges.
Vibration-based energy harvesting circuits are totally case dependent. First, you should know how much kinetic energy with how many cycles is applied to the piezoelectric material, then you can estimate the range of electrical power output (from microwatt to milliwatt). Furthermore, piezoelectric transducers usually generate the high voltage (1~10 V) with very low current (1 uA ~ 1 mA). Therefore, depending on the impedance of the electrical load that you convey the power to it you can choose which circuits to use. SSHI circuits are good for weakly coupled systems, and for strongly coupled systems they operate as same as the normal rectifiers (full-wave bridge converters).
I hope this is helpful for your research,
For further information, you can reach me at "[email protected]"
Amir,
See last month or two of IEEE Circuits and systems for some ideas. I have found that the biggest problem to be making the resonate frequency of the mechanical pump system wide enough to actually drive the system. You can model a mechanical resonator as a band pass filter to drive the piezo to get the response you want. You will discover that driving a load inductor (SSHI) is going to help with the bandwidth and help achieve a wider band critical damping of the piezo element. Also, use zero bias Schottky diodes in parallel with main energy path as voltage multiplier to get enough voltage to power up the actual SSHI MOSFET switches with a driver control IC. This will solve the start up problem.
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