Energy Harvesting

1
Energy Harvesting

• Name Alex Phipps
• Goals
• Measure and characterize the efficiency of each
  stage of the direct charging circuit.
• Compare efficiency measurements to simulation
  data.
• Completely understand Shengwens circuits
• Key accomplishments.
• Gathered and processed data for efficiency of
  direct charge.
• Measured mechanical power into the system.
• Calculated efficiency for mechanical to
  electrical conversion.
• Calculated electrical efficiency for the
  rectifier circuitry.
• Key issues
• Simulations do not match up with the
  measurements.
• The sims are very inefficient.
• Measured efficiencies are low because of losses
  on resistors.

2
Beam Data

• Mechanical data was gathered using an
  accelerometer and a displacement sensor.

Vaccel (p2p) mV Acc (rms) m/s2 F(rms) N disp (rms) m velocity (rms) m/s Power Beam uW
44 4.0882 4.4970E-04 1.31E-04 1.64E-01 73.87
56.6 5.3726 5.9099E-04 1.74E-04 2.18E-01 128.70
66.4 6.2869 6.9156E-04 2.11E-04 2.64E-01 182.67
76.4 7.3074 8.0381E-04 2.49E-04 3.11E-01 250.18
85.6 8.0942 8.9036E-04 2.81E-04 3.51E-01 312.43
97.2 9.1986 1.0118E-03 3.20E-04 4.00E-01 404.28
108 10.165 1.1182E-03 3.51E-04 4.39E-01 490.89
3
Beam Efficiency
Beam efficiency is defined as electrical power
from the beam divided by mechanical power into
the beam.
4
Electrical statistics
Vin (rms) V Iin (rms) A Power In uW Vbat V Ibat A Power battery uW
2
1.967 9.54E-06 18.77 2 4.00E-06 8.00
2.045 1.12E-05 22.94 2 5.90E-06 11.80
2.1197 1.34E-05 28.30 2 8.00E-06 16.00
2.1714 1.52E-05 32.94 2 9.75E-06 19.50
2.2231 1.71E-05 37.97 2 1.18E-05 23.50
2.1998 1.87E-05 41.06 2 1.35E-05 27.00
5
Converter Efficiency
6
Overall Efficiency
Total Efficiency Converter EfficiencyBeam
Efficiency