Download 14PE1 Maximum power transfer tracking for Ultralow

14PE1
Maximum power transfer tracking for
Ultralow-power electromagnetic energy harvesters
Szarka, G.D. ; Bristol, UK ; Proynov, P.P.
Power Electronics, IEEE Transactions on (Volume:29 , Issue: 1 )
DOI: 10.1109/TPEL.2013.2251427
Publication Year: 2013, Page(s): 201 - 212
Project Title
:
Maximum power transfer tracking for
Ultralow-power electromagnetic energy harvesters
Domain
:
Power Electronics
Reference
:
IEEE
Publish Year
:
2014 Page(s): 201 - 212
D.O.I
:
10.1109/TPEL.2013.2251427
Software Used
:
MATLAB
Developed By
:
Wine Yard Technologies, Hyderabad
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14PE1
Maximum power transfer tracking for
Ultralow-power electromagnetic energy harvesters
This paper describes the design and operation of power conditioning system with maximum
power transfer tracking (MPTT) for low-power electromagnetic energy harvesters. The
system is fully autonomous, starts up from zero stored energy, and actively rectifies and
boosts the harvester voltage. The power conditioning system is able to operate the
harvester at the maximum power point against varying excitation and load conditions,
resulting in significantly increased power generation when the load current waveform has a
high peak-to-mean ratio. First, the paper sets out the argument for MPTT, alongside the
discussion on the dynamic effects of varying electrical damping on the mechanical structure.
With sources featuring stored energy, such as a resonant harvester, maximum power point
control can become unstable in certain conditions, and thus, a method to determine the
maximum rate of change of electrical damping is presented. The complete power
conditioning circuit is tested with an electromagnetic energy harvester that generates
600mVrms ac output at 870μWunder optimum load conditions, at 3.75 m·s−2 excitation.
The digital MPTT control circuit is shown to successfully track the optimum operating
conditions, responding to changes in both excitation and the load conditions. At 2 Vdc
output, the total current consumption of the combined ancillary and control circuits is just
22μA. The power conditioning system is capable of transferring up to 70% of the potentially
extractable power to the energy storage.
.
1. The output of small electromagnetic energy harvesters typically requires rectification
and boosting in order to produce an output voltage that falls within the allowable
operating range of the load electronics. In some applications, there is also a need to
buffer energy in high capacity storage elements, such as super capacitors, in order to
supply loads with a higher peak demand than the harvester output . Several circuit
architectures have been reported in published literature, which meet these
requirements, including single-stage ac–dc switch-mode power converters .
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14PE1
2. Efficiencies up to 75%–80% at 500μW level have been reported . However, in order
to achieve the maximum potential power of an energy harvester, it is important that
the power conditioning system provides the optimum load for the generator for the
particular input and output conditions.
Conclusion:
The work presented in this paper aimed to address the challenges that arise from
implementing MPTT for low-power, kinetic electromagnetic energy harvesters. The
transient response of the single-degree-of-freedom mechanical system is presented and
discussed using experimental results and analytical derivations. A method that aids the
design of perturb-and-observe algorithm-based control with discrete perturbations of the
control parameter is presented: the minimum time required between perturbations in order
to allow the mechanical structure to settle is calculated for highly under damped mass–
spring–damper systems under the assumption of a constant, sinusoidal, non-direct
excitation that occurs at the natural resonance frequency of the mechanical structure.
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14PE1
Screen Shots:
Input Voltage and current
Output voltage and current
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