Effect of the Sampling Parameters in FOCV-MPPT Circuits for Fast-Varying EH Sources

Carandell, Matias; Holmes, Andrew S.; Toma, Daniel Mihai; Rı́o, Joaquı́n Del; Gasulla, Manel

doi:10.1109/tpel.2022.3216109

Cited by 5 publications

(9 citation statements)

References 16 publications

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“…In the long term, all the instants within a period To, where the The result in Equation ( 3) is achieved for the case of high sampling rates. In [16], it is shown that 99% of the maximum power is achieved for f s = 15f o . For any waveform type, Equation ( 3) is achieved whenever f s >> f omax , with f omax being the maximum frequency component of v ac .…”

Section: Rt Vt Vomentioning

confidence: 99%

“…In [16], experimental tests were carried out with a WEC embedded into a drifter and attached to a linear shaker (APS 129), with an excitation frequency of 2 Hz (f o ), in order to emulate the drifter's movement under a sea environment (Section V.C of [16]). A block schematic and a picture of the experimental setup are shown in Figures 4 and 5, respectively.…”

Section: Test With a Wecmentioning

confidence: 99%

“…A Li-ion rechargable battery of 165 mAh and 3.7 V was placed as a load at the PMU's output. An oscilloscope (Lecroy Wavesurfer 3024) was used to measure both v o and i o (this last one also using a shunt resistor and a current sense amplier as described in [16]). From these parameters, input power to the PMU can be estimated.…”

Section: Test With a Wecmentioning

confidence: 99%

“…Expressions are provided and experimentally validated for a 153.6 Hz sinusoidal acceleration whose amplitude is modulated by a 50 s period saw-tooth waveform with acceleration ranging from 0.75 g to 1.25 g. For the FOCV method, an optimum T s of 16.7 s with a t SAMP of 0.3 s is the result. An approximate analytical expression is provided in [16] for the harvested power with the FOCV method, considering a sinusoidal waveform for the EH transducer. It is shown that for negligible sampling times, the larger the sampling rate, the larger the harvested power, and that 99% of the maximum power can be obtained with a sampling rate just 15 times that of the EH transducer's frequency.…”

Section: Introductionmentioning

confidence: 99%

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Power Gain from Energy Harvesting Sources at High MPPT Sampling Rates

Gasulla

Carandell

2023

Sensors

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Energy harvesting (EH) sources require the tracking of their maximum power point (MPP) to ensure that maximum energy is captured. This tracking process, performed by an MPP tracker (MPPT), is performed by periodically measuring the EH transducer’s output at a given sampling rate. The harvested power as a function of the sampling parameters has been analyzed in a few works, but the power gain achieved with respect to the case of a much slower sampling rate than the EH source’s frequency has not been assessed so far. In this work, simple expressions are obtained that predict this gain assuming a Thévenin equivalent for the EH transducer. It is shown that the power gain depends on the relationship between the square of AC to DC open circuit voltage of the EH transducer. On the other hand, it is proven that harvested power increases, using a suitable constant signal for the MPP voltage instead of tracking the MPP at a low sampling rate. Experimental results confirmed the theoretical predictions. First, a function generator with a series resistor of 1 kΩ was used, emulating a generic Thévenin equivalent EH. Three waveform types were used (sinus, square, and triangular) with a DC voltage of 2.5 V and AC rms voltage of 0.83 V. A commercial MPPT with a fixed sampling rate of 3 Hz was used and the frequency of the waveforms was changed from 50 mHz to 50 Hz, thus effectively emulating different sampling rates. Experimental power gains of 11.1%, 20.7%, and 7.43% were, respectively, achieved for the sinus, square, and triangular waves, mainly agreeing with the theoretical predicted ones. Then, experimental tests were carried out with a wave energy converter (WEC) embedded into a drifter and attached to a linear shaker, with a sinus excitation frequency of 2 Hz and peak-to-peak amplitude of 0.4 g, in order to emulate the drifter’s movement under a sea environment. The WEC provided a sinus-like waveform. In this case, another commercial MPPT with a sampling period of 16 s was used for generating a slow sampling rate, whereas a custom MPPT with a sampling rate of 60 Hz was used for generating a high sampling rate. A power gain around 20% was achieved in this case, also agreeing with the predicted gain.

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Section: Rt Vt Vomentioning

confidence: 99%

Section: Test With a Wecmentioning

confidence: 99%

Section: Test With a Wecmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Power Gain from Energy Harvesting Sources at High MPPT Sampling Rates

Gasulla

Carandell

2023

Sensors

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“…For example, [12], the Flyback converter is employed. There is no restriction on the converter to be used because a short circuit is never generated in the panel, or the panel is never disconnected from the converter (some algorithms need to perform these actions to obtain the MPP, for example, the fractional open circuit voltage (FOCV) and fractional short circuit current (FSCC) method) [18,19]. The disadvantage of the proposed scheme is that it will continuously oscillate even when the GMPP is reached (smaller oscillations will be generated).…”

Section: Introductionmentioning

confidence: 99%

A Comprehensive Control Strategy for a Push–Pull Microinverter Connected to the Grid

et al. 2023

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The effects of partial shading or dust accumulation on the panels of photovoltaic systems connected to the grid can generate a considerable reduction in energy performance, being necessary to provide the appropriate voltage to the grid regardless of the irradiance level. This paper addresses this problem and presents a comprehensive control strategy and its implementation for a grid-connected microinverter composed of a push–pull converter followed by an H-bridge inverter. In the push–pull converter, a hybrid MPPT algorithm and a PI control enable work in the MPP of the PV panel. In the H-bridge inverter, a cascade control consisting of a PI control and a predictive control allows the connection to the grid. A proof-of-concept prototype is implemented in order to validate the proposal. Experimental tests were performed by connecting the microinverter to a PV panel and a programmable photovoltaic panel emulator to check the MPPT performance. Furthermore, partial shading conditions were simulated on the dc source to check if the global maximum power point is reached. Experimental results demonstrate the feasibility of the topology and the control approach, obtaining MPPT performance in the topology above 99% at different power and voltage levels on the MPPT, even in the presence of partial shading conditions.

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