DESIGN AND SIMULATION OF HIGH-PERFORMANCE MULTILEVEL INVERTERS FOR RENEWABLE ENERGY SYSTEMS

Abstract

This study presents the modeling and simulation of single-phase and three-phase Sinusoidal Pulse Width Modulation (SPWM) inverter systems powered by photovoltaic (PV) panels, wind turbines, and fuel cells, incorporating Maximum Power Point Tracking (MPPT) algorithms to optimize energy harvesting. The renewable sources used in the system generate output DC voltages of approximately 310V from PV, 60V from the wind turbine, 215V from the fuel cell, and 25.9V from bidirectional batteries. Proportional-Integral (PI) controllers are employed to ensure high-quality sinusoidal waveforms and to minimize Total Harmonic Distortion (THD). Under resistive load conditions, the single-phase inverter produced a THD in output voltage (THDvo) of 0.65419%, with a root mean square (RMS) output voltage (VoRMS) of 217.3617V and load current (IoRMS) of 3.1052A. For the three-phase inverter operating under a resistive load, the THDvo was recorded at 1.5146%, with VoRMS of 218.4261V and IoRMS of 2.1843A. When operating under inductive load conditions, the THDvo increased slightly to 1.5969%, while the THD of load current (THDio) was 1.2905%, with VoRMS and IoRMS at 214.201V and 2.0916A, respectively. In addition, this work investigates the design and performance of an asymmetrical 49-level cascaded H-bridge inverter powered by renewable sources. Three configurations of the 49-level inverter were evaluated: (1) using a per-unit voltage structure of 1:2:7:14, (2) applying actual voltage values of 40:80:280:560V, and (3) employing PV modules that produce voltages close to those actual values. The per-unit system achieved VoRMS = 16.9719V, IoRMS = 1.0569A, THDvo = 0.71216%, and THDio = 0.093319%. With the actual voltage setup, the system reached VoRMS = 679.0492V, IoRMS = 4.265A, THDvo = 0.71227%, and THDio = 0.16719%. Using PV modules under 1000W/m² irradiance and 25°C temperature, the output was VoRMS = 692.7293V, IoRMS = 43.1367A, THDvo = 1.2926%, and THDio = 0.33963%. Finally, the study introduces and simulates a 343-level asymmetrical multilevel inverter configuration. For the per-unit voltage configuration (1:2:7:14:49:98), the inverter yielded VoRMS = 120.9316V, IoRMS = 3.7178A, THDvo = 0.32422%, and THDio = 0.22506%. The actual voltage case achieved VoRMS = 4838.7577V, IoRMS = 6.7445A, THDvo = 0.32414%, and THDio = 0.25682%. With PV modules under 1000W/m² and 25°C, the system delivered VoRMS = 4827.9768V and IoRMS = 148.4073A, with THDvo = 0.90328% and THDio = 0.54142%. These findings confirm the effectiveness of multilevel inverter topologies and PI-based control in ensuring high-quality power output with minimal harmonic distortion in renewable energy systems.