Power Gain from Energy Harvesting Sources at High MPPT Sampling Rates

Area of Science:

• Electrical Engineering
• Renewable Energy Systems
• Power Electronics

Background:

• Energy harvesting (EH) systems require maximum power point tracking (MPPT) for optimal energy capture.
• Current MPPT methods involve periodic sampling, but the impact of sampling rate on harvested power gain is not fully understood.

Purpose of the Study:

• To derive simple expressions for predicting power gain in EH systems based on sampling rates.
• To assess the power gain achieved by optimizing the sampling rate of the maximum power point tracker (MPPT).

Main Methods:

• Developed theoretical expressions for power gain using a Thévenin equivalent model for EH transducers.
• Conducted experiments with a function generator emulating EH sources (sinusoidal, square, triangular waveforms) and a wave energy converter (WEC).
• Compared power output using commercial and custom MPPTs with varying sampling rates.

Main Results:

• Theoretical predictions show power gain depends on the ratio of AC to DC open-circuit voltage.
• Experimental power gains of 11.1%, 20.7%, and 7.43% were observed for sinusoidal, square, and triangular waveforms, respectively.
• A power gain of approximately 20% was achieved with a wave energy converter using optimized sampling rates.

Conclusions:

• Optimizing MPPT sampling rates can significantly increase harvested power.
• The findings provide valuable insights for designing more efficient energy harvesting systems.
• Using a suitable constant voltage signal for MPPT can outperform low-sampling-rate tracking.