Additional Funding Sources
The project described was supported by the National Science Foundation via the Research Experience for Undergraduates Site: Materials for Society (Award Nos. DMR 1658076 and 1950305) and by Boise State University.
Abstract
Vibrational energy harvesting is an emergent technology that uses vibrations to generate electrical energy using piezoelectric or magnetostrictive materials. In the case of magnetostrictive materials, mechanical stress causes the material to generate a magnetic field which can induce an electrical current in a pickup coil. This project takes the output voltage from the pickup coil and seeks to provide a usable DC voltage. Two circuits were used to attempt this, a transformer leading into a voltage rectifier or a voltage multiplication circuit leading into a DC voltage booster. The transformer was used to increase the AC coil voltage to a level where the rectifier chip could activate and output a DC voltage. Voltage multiplication circuits using diodes and capacitors, called Cockcroft-Walton generator circuits, can ideally have a DC output higher than the peak AC input voltage. A four times multiplier worked well, giving off a low, near DC voltage. DC amplification was tested with a demo board intended to increase low voltage DC to a variable DC output. In testing this board by itself, it worked to boost DC voltage and power a 2V LED. Running either of the circuits off of the beam and pickup coil was ineffective due to the total input impedance of the circuits. Results show that the circuits work when powered by a function generator, meaning that a more powerful beam and pickup coil setup is necessary.
Methods of Voltage Amplification for Magnetostrictive Energy Harvesters
Vibrational energy harvesting is an emergent technology that uses vibrations to generate electrical energy using piezoelectric or magnetostrictive materials. In the case of magnetostrictive materials, mechanical stress causes the material to generate a magnetic field which can induce an electrical current in a pickup coil. This project takes the output voltage from the pickup coil and seeks to provide a usable DC voltage. Two circuits were used to attempt this, a transformer leading into a voltage rectifier or a voltage multiplication circuit leading into a DC voltage booster. The transformer was used to increase the AC coil voltage to a level where the rectifier chip could activate and output a DC voltage. Voltage multiplication circuits using diodes and capacitors, called Cockcroft-Walton generator circuits, can ideally have a DC output higher than the peak AC input voltage. A four times multiplier worked well, giving off a low, near DC voltage. DC amplification was tested with a demo board intended to increase low voltage DC to a variable DC output. In testing this board by itself, it worked to boost DC voltage and power a 2V LED. Running either of the circuits off of the beam and pickup coil was ineffective due to the total input impedance of the circuits. Results show that the circuits work when powered by a function generator, meaning that a more powerful beam and pickup coil setup is necessary.