Electrical Power Transfer with “No Wires” - Energy Harvesting Autonomous Sensor Systems - page 186

TABLE 6.1
Measured and Calculated-Induced EMF Voltage for Different Current Flowing in the
Power Line

Measured and Calculated Induced EMF Voltage
V emf = NBAsin( t )

I, B

Calculated 0 r I / 2 r a Area Current Measured

r b )

Flowing in 2 f r a at ( V emf V emf

Power Line r fat50Hz N 1.5cm r b ∼ 0.5cm ( V rms ) ( V rms )

10 − 5

4A 1500 100 500 0.08 T 2 . 5 × 0.987 1.025

10 − 5

. ×

3A 1500 100 500 0.06 T 2 5 0.740 0.748

10 − 5

. ×

2A 1500 100 500 0.04 T 2 5 0.493 0.449

10 − 5 1A 1500 100 500 0.02 T 2 . 5 × 0.247 0.194

6.1.1.1 Performance of the Magnetic Energy Harvester
To study how the magnetic energy harvester performed under various op-
erating conditions, experiments were carried out on the designed magnetic
energy harvester. Referring to Table 6.1 , the open-circuit voltage of the har-
vester, which consists of one toroid coil, was quite low, ranging from 0.2 to
1V.Inorder to achieve a higher output voltage, three sets of ferrite cores were
connected in series. The improved version of the magnetic energy harvester
was connected to different loading resistances, and the source current flowing
in the power line was varied between 1 to 4 A. This was to find out the per-
formance of the harvester for various input and output operating conditions.
The data collected is plotted into the current versus voltage (I-V) curve and
power curve as shown in Figures 6.5 and 6.6 , respectively.

Current (mA) vs. Voltage (V)

14

4 A
3 A
2 A
1 A

12

10

8

6

4

2

0

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

Voltage (V)

FIGURE 6.5
Voltage versus current curve for various input currents.