Dear scholars,
Suppose we have a vibration-based piezoelectric energy harvester (cantilever beam), the generated voltage is measureable via a multimeter. Questions are:
1- how to measure the harvested power? What type of electric circuit is required?
2- Do we need a rectifier to change the AC current into DC current? (Knowing that the appliance to be charged needs DC current)
3- do we need a battery or a capacitor to store and use the energy?
Hi Alireza Babaei ,
1: a) If you are just interested in the usable power, and if you know the IV characteristic of your load, measure the voltage at the load, and calculate the power.
Still case a) but the current has be measured for some reason: If a small reduction of the usable power is tolerable, simply use a multimeter. If any reduction of usable power has to be avoided, and if the current is high enough, use a current clamp which is able to measure DC.
b) If you want to measure the power provided by the piezoelectric beam (e.g. in order to calculate the efficiency of the rectifier), you have to measure the AC current of the beam, either by a galvanically connected instrument or by a current clamp (no DC ability necessary). The difference to case a) is that even the current clamp introduces a (small) impedance.
2: Yes. The dilemma: With a single diode, you would get only halfwaves of one polarity; with a rectifier bridge, you would have always two diodes in series to the load. Possible solution: Charge alternatingly two capacitors, one for each polarity. This way, two diodes are enough, and only one is in series to the load at each moment.
3: Depends on the application: If the vibration is permanent, and if the load can be supplied with unipolar voltage and current pulses, then batteries or capacitors are not neccessary. If the vibration is permanent but the load tolerates only a small AC component then you would need at least one (or two, see point 2) capacitor(s). If the vibration ceases at times but the load has to be powered permantly, a battery (rechargeable, of course) is necessary.
Using bridge rectifier and filter, convert to D.C voltage (V) from A.C . Using stander resistance (R)load the D.C voltage and find the flowing maximum current (I). The power could be obtained as W=(V)(I) or (I)(I)R, obtained power by both ways should be same. Thus after knowing the available power the D.C appliance could be used with in the ratings ...
Still in doubt? I'm working on exactly that for my doctorate.
Dear ALI,
- You can measure the power by using this formula: P = V^2/R. You do not need to have a circuit and you can use open-circuit voltage (AC). You need to use 10^6 to represent the very high amount for R. In reality it should be an infinite value but some researchers have used this amount as a solution and you may like to try as well.
- You always need a circuit to convert AC to DC but if your field is not electronic just use the traditional one. Without using these circuits you can not save power in batteries or capacitors.
- You can use Ni. Mh batteries or small capacitors to save power but as current is very low it takes a long time to charge them.
Regards
Yes sir. we can measure the power using the formula P=V^2/R. But in this formula, V is related to load voltage and in Ac circuits we have to take RMS voltage. In order to charge the storage systems, it requires conversion systems like rectifiers and DC-DC systems. By using a traditional diode rectifier, will have more power dissipation. I am working on both mechanical design and electronic circuit design.
Regards.
The electric power generated by a piezoelectric energy harvester can be used to power a variety of devices, including:
- Sensors: Piezoelectric energy harvesters can be used to power sensors that are used to collect data in remote or harsh environments. For example, piezoelectric energy harvesters can be used to power sensors that are used to monitor environmental conditions, such as temperature, humidity, and air quality.
- Wireless devices: Piezoelectric energy harvesters can be used to power wireless devices, such as RFID tags and sensors. For example, piezoelectric energy harvesters can be used to power RFID tags that are used to track the movement of goods in a warehouse.
- Low-power devices: Piezoelectric energy harvesters can be used to power low-power devices, such as LED lights and calculators. For example, piezoelectric energy harvesters can be used to power LED lights that are used to illuminate walkways or pathways.
The amount of power that can be generated by a piezoelectric energy harvester depends on a number of factors, including the size of the harvester, the type of material that is used, and the amount of stress that is applied to the harvester. In general, piezoelectric energy harvesters are most effective at generating power from low-frequency vibrations.
Piezoelectric energy harvesters are a promising technology for powering a variety of devices in remote or harsh environments. As the technology continues to develop, it is likely that piezoelectric energy harvesters will become more common and affordable. Here are some additional tips for using the electric power generated by a piezoelectric energy harvester:
- Choose the right harvester for the application. There are different types of piezoelectric energy harvesters, each with its own advantages and disadvantages. Some harvesters are better suited for applications where the power output is important, while others are better suited for applications where the size or weight of the harvester is important.
- Consider the environment. The environment in which the harvester will be used can affect its performance. For example, harvesters that are used in hot environments may need to be de-rated to account for the increased temperature.
- Monitor the harvester. It is important to monitor the harvester to ensure that it is not over-stressing. Over-stressing can damage the harvester and shorten its lifespan.
By following these tips, you can maximize the performance of your piezoelectric energy harvester and extend its lifespan.
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