Cascaded H-Bridge Multilevel Inverter

Multilevel inverters are widely used in renewable energy systems because they can generate stepped alternating-current (AC) voltage waveforms with improved power quality compared with conventional two-level inverters. This paper presents the MATLAB/Simulink modelling and simulation analysis of a five-level cascaded H-bridge multilevel inverter integrated with solar photovoltaic (PV) and fuel-cell energy sources. The solar PV output is processed through a maximum power point tracking (MPPT) controller and a DC–DC boost converter to provide the required DC-link voltage. A fuel-cell stack supplies the second DC source. The inverter employs insulated-gate bipolar transistor (IGBT) switches and pulse-width modulation to convert DC power into a stepped AC output for a motor load. The system performance is evaluated using solar output voltage, inverter output voltage, motor-speed response, and total harmonic distortion (THD). The simulated solar voltage settles at approximately 64 V, while the inverter output exhibits multiple voltage levels. The recorded FFT analysis indicates a THD of 31.87% with a fundamental frequency of 50 Hz. These results demonstrate the operation of the simulated renewable-energy-fed multilevel inverter and identify the need for further harmonic reduction and output-voltage optimization.