Transcript Harvesting acoustic energy using a straight

Low frequency acoustic energy
harvester and the interface circuit
Bin Li and Jeong Ho You
Energy Harvesting Materials Lab
Department of Mechanical Engineering
Southern Methodist University
1
Objective: harvesting wasted acoustic energy
(1)Abundant, clean and renewable
(2)Intensive in urban life
(2)Currently wasted
(3)Low energy density
Various sound sources
2
Approach
Develop an acoustic energy harvester:
• Low audible operating frequency(about 100~200Hz)
• High efficiency
Accumulated
acoustic energy
Quarter wavelength
resonator
Vibration to
electricity
Piezoelectric
cantilevered plate
AC/DC
conversion
External circuit
3
Multiple piezo plates placed along the resonator
Total output voltage and power as a
function of incident SPL
The number of plates to generate the maximum voltage
SPL: 100dB
The summation of power: and power is limited by the interruption of air particle
motion.
4
Interface AC/DC conversion circuit design
Piezo plates
Electric power Pe flowing
into the circuit
Pe=Ieq×Vp
Standard
circuit
Time
Pe=Ieq×Vp
Self-powered
P- SSHI circuit
Time
Self-powered SSHI allow more electric power flowing into the circuit
and improve AC/DC conversion efficiency by switching technology.
5
Harvested powers in our acoustic energy
harvester Incident SPL: 112 dB
Conclusions:
• Acoustic energy harvesting mechanism is developed at low operating frequency (100~200
Hz) using quarter-wavelength straight-tube resonator with multiple piezoelectric
cantilever plates;
• The number of plates to generate the maximum voltage and power are limited by the
interruption of acoustic air particle motion caused by the presence of plates;
• When the incident SPL is 112 dB, the simulated output power of the acoustic energy
6
harvester is 2.9813mW using self-powered P-SSHI circuit.