Design Article
Energy harvester produces power from local environment, eliminating batteries in wireless sensors
Jim Drew, Eliminating Batteries in Wireless Sensors, Linear Technology
5/2/2011 10:12 AM EDT
Application examples
The LTC3588-1 requires the output voltage of the transducer to be above the undervoltage lockout rising threshold limit for the specific output voltage set at the D0 and D1 input pins. For maximum energy transfer, the energy transducer must have an open circuit voltage of twice the input operating voltage and a short-circuit current of twice the input current required. These requirements must be met at the minimum excitation level of the source to achieve continuous output power.
Piezoelectric transducer application
Figure 3 shows a piezoelectric system that, when placed in an air stream, produces 100μW of power at 3.3V. The deflection of the piezoelectric element is 0.5cm at a frequency of 50Hz.
The LTC3588-1 requires the output voltage of the transducer to be above the undervoltage lockout rising threshold limit for the specific output voltage set at the D0 and D1 input pins. For maximum energy transfer, the energy transducer must have an open circuit voltage of twice the input operating voltage and a short-circuit current of twice the input current required. These requirements must be met at the minimum excitation level of the source to achieve continuous output power.
Piezoelectric transducer application
Figure 3 shows a piezoelectric system that, when placed in an air stream, produces 100μW of power at 3.3V. The deflection of the piezoelectric element is 0.5cm at a frequency of 50Hz.
Seebeck transducer application
Figure 4 shows an energy harvesting system that uses a Seebeck transducer from Tellurex Corporation. A heat differential produces an output voltage that supports a 300mW output load. Connecting the transducer to the PZ1 input prevents reverse current from flowing back into the Seebeck device when the heat source is removed. The 100Ω resistor provides current limiting to protect the LTC3588-1 input bridge.
Harvest energy from the EM field produced by standard fluorescent lights
This application requires some outside-the-box thinking. Figure 5 shows a system that harvests energy from the electric fields surrounding high voltage fluorescent tubes. Two 12” × 24” copper panels are placed 6” from a 2’ × 4’ fluorescent light fixture. The copper panels capacitively harvest 200μW from the surrounding electric fields and the LTC3588-1 converts that power to a regulated output.
Conclusions
The LTC3588-1 allows remote sensors to operate without batteries by harvesting ambient energy from the surrounding environment.
It contains all the critical power management functions: a low loss bridge rectifier, a high efficiency buck regulator, a low bias UVLO detector that turns the buck converter on and off, and a PGOOD status signal to wake up the microcontroller when power is available. The LTC3588-1 supports loads up to 100mA with just five external components.
Courtesy of EE Times Europe
Figure 4 shows an energy harvesting system that uses a Seebeck transducer from Tellurex Corporation. A heat differential produces an output voltage that supports a 300mW output load. Connecting the transducer to the PZ1 input prevents reverse current from flowing back into the Seebeck device when the heat source is removed. The 100Ω resistor provides current limiting to protect the LTC3588-1 input bridge.
Harvest energy from the EM field produced by standard fluorescent lights
This application requires some outside-the-box thinking. Figure 5 shows a system that harvests energy from the electric fields surrounding high voltage fluorescent tubes. Two 12” × 24” copper panels are placed 6” from a 2’ × 4’ fluorescent light fixture. The copper panels capacitively harvest 200μW from the surrounding electric fields and the LTC3588-1 converts that power to a regulated output.
Conclusions
The LTC3588-1 allows remote sensors to operate without batteries by harvesting ambient energy from the surrounding environment.
It contains all the critical power management functions: a low loss bridge rectifier, a high efficiency buck regulator, a low bias UVLO detector that turns the buck converter on and off, and a PGOOD status signal to wake up the microcontroller when power is available. The LTC3588-1 supports loads up to 100mA with just five external components.
Courtesy of EE Times Europe
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iniewski
5/11/2011 10:52 AM EDT
Jim, interesting article, I am editing a book on energy harvesting, would you be interested in contributing a chapter? kris.iniewski@gmail.com
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tjordan54
5/11/2011 1:23 PM EDT
It's all frequency!
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anne-francoise.pele
7/24/2012 5:47 AM EDT
Click on the link below to check out the collection of the Design Articles, Case Studies, Product How-To articles, Teardowns, etc... related to energy scavenging that have been published on Smart Energy Designline.
Click here: http://www.eetimes.com/design/smart-energy-design/4372778/Energy-harvesting---Design-archive
Check back frequently. The list will be updated as new articles arrive.
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Fredrodriguez55
11/1/2012 12:44 AM EDT
I have read somewhere that such energy harvesters have some environmental side effects, which may be harmful in the long run. However, I have not seen any empirical results of similar devices, nor for this current device being featured above. Would you be able to provide references to expert opinions, specifically engineers or consultants in the field? It would be great to have some references apart from the ones I find on the web. Books, or journals would be great to have.
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iniewski
11/1/2012 10:19 AM EDT
What could be harmful about energy harvesting??? If anything it saves energy so it is beneficial to environment...Kris
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