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Efficiency of maximum power point tracking in photovoltaic system under variable solar irradiance

Marańda W., Piotrowicz M.

Bulletin of the Polish Academy of Sciences. Technical Sciences

2014

Vol. 62, nr 4

713--721

Field conditions decrease the energy output of photovoltaic (PV) systems, mainly due to excessive temperatures. However, in regions with moderate ambient temperatures, as in Poland, solar energy is commonly delivered with highly fluctuating irradiance. This introduces yet another source of energy losses due to the non-ideal tracking of actual position of Maximum Power Point (MPP). Majority of PV-systems are equipped with DC/AC and grid-connected inverter. Since the solar energy flux is variable, an adequate MPP-tracking algorithm is required to handle a wide range of load levels and face rapid changes of input power. Along with the essential DC/AC conversion, the quality of MPP-tracking must also be taken into account in evaluation of inverter efficiency. The tracking in dynamic conditions has been addressed only recently. Several algorithms has been studied theoretically, experimentally or in laboratory conditions by applying artificial input test-patterns. This work takes the opposite approach by applying the recorded real-life solar irradiance and simulating the tracking behavior to study the problem for true field conditions in Poland. The simulation uses the unique high-quality irradiance data collected with 200 ms time resolution. The calculation of both static and dynamic MPP-tracking efficiency has been performed for representative variable-cloudy day, applying commonly used Perturb&Observe tracking algorithm.

Falownik klasy DE 8 MHz/300 W z rezonansowym sterownikiem klasy D o sinusoidalnym kształcie napięcia bramkowego

Kasprzak M.

Przegląd Elektrotechniczny

2013

R. 89, nr 2a

28--33

W artykule opisano podstawy działania falownika klasy DE oraz ideę sterowania napięciem sinusoidalnym. Obwód główny falownika klasy DE o strukturze półmostka zawiera RF Power Mosfet 501N21A a falownik sterujący klasy D bazuje na drajwerze scalonym DEIC 420. Przedstawiono najważniejsze oscylogramy oraz zmierzone charakterystyki sterowania mocy oraz sprawności: drenowej (83-85%) i całkowitej (80-82%). Przedyskutowano ograniczenia zastosowania sterowania sinusoidalnego oraz podano wytyczne projektowe dla falownika klasy DE.

Principle of operation of Class DE inverter and idea of sinusoidal driving of transistors have been presented in the paper. The power board of Class DE inverter contains RF Power Mosfet 501N21A, Class D driving inverter is based on IC driver DEIC 420. Oscillograms, measurements of output power characteristics and the inverter efficiency, drain (83-85%) and total (80-82%), were depicted. Limits of application of sinusoidal driving and design guidelines of DE inverter were discussed.(8 MHz/300 W Class DE Inverter with Class D sinusoidal gate voltage resonant driver.