TY - JOUR
T1 - Modified five-level LLC resonant inverter for multiple PV string systems
AU - Bughneda, Ali
AU - Salem, Mohamed
AU - Swadi, Mahmood
AU - Prabaharan, Natarajan
AU - Hossain, Eklas
AU - Ishak, Dahaman
AU - Mohamed, Faisal A.
N1 - Publisher Copyright:
© 2025 The Authors
PY - 2025/5
Y1 - 2025/5
N2 - A modified multilevel LLC resonant inverter for multi-string photovoltaic (PV) applications. An efficient variable frequency and an integrated control method for the modulation index is proposed. To obtain the best efficiency, a steady output voltage gain, “ZVS, and a wide range of load variation, the designed LLC tank has been developed to run with a frequency range close to or at a resonant frequency. All the selected parameters for the analysis were emphasized in detail. Furthermore, the behaviour of the developed converter was investigated under varying load conditions at nominal input voltage, and under conditions of varying solar insolation and at full load. It was found that the control system responded to both changes successfully and maintained the value of the output voltage at its expected level by varying the switching frequency within a selected range, and produced 1000V,5kW with 97.6% efficiency. Also, the developed five-level converter differed in LLC resonant behaviour compared to its typical behaviour with conventional full/half-bridge converters, as the LLC RC operated below resonant frequency under all load and input conditions. The theoretical results were validated experimentally using a lab prototype and through simulation using MATLAB-SIMULINK. Selected findings were discussed to portray the efficacy of the designed converter.
AB - A modified multilevel LLC resonant inverter for multi-string photovoltaic (PV) applications. An efficient variable frequency and an integrated control method for the modulation index is proposed. To obtain the best efficiency, a steady output voltage gain, “ZVS, and a wide range of load variation, the designed LLC tank has been developed to run with a frequency range close to or at a resonant frequency. All the selected parameters for the analysis were emphasized in detail. Furthermore, the behaviour of the developed converter was investigated under varying load conditions at nominal input voltage, and under conditions of varying solar insolation and at full load. It was found that the control system responded to both changes successfully and maintained the value of the output voltage at its expected level by varying the switching frequency within a selected range, and produced 1000V,5kW with 97.6% efficiency. Also, the developed five-level converter differed in LLC resonant behaviour compared to its typical behaviour with conventional full/half-bridge converters, as the LLC RC operated below resonant frequency under all load and input conditions. The theoretical results were validated experimentally using a lab prototype and through simulation using MATLAB-SIMULINK. Selected findings were discussed to portray the efficacy of the designed converter.
KW - DC-DC Converters
KW - LLC Resonant Converter
KW - Modified Five-Level Inverter (MMLI)
KW - PV Systems
KW - Zero Voltage Switching (ZVS)
UR - http://www.scopus.com/inward/record.url?scp=86000798749&partnerID=8YFLogxK
U2 - 10.1016/j.aej.2025.02.096
DO - 10.1016/j.aej.2025.02.096
M3 - Article
AN - SCOPUS:86000798749
SN - 1110-0168
VL - 122
SP - 215
EP - 228
JO - Alexandria Engineering Journal
JF - Alexandria Engineering Journal
ER -
