Design and Implementation of a Closed-Loop Single-Phase Transistor-Clamped H-Bridge Multilevel Inverter Using FPGA

This paper presents the performance evaluation of a single-phase five-level transistor-clamped H-bridge (TCHB) inverter, which is a modified circuit based on H-bridge inverter topology involving closed-loop control. The modulation technique used here is multicarrier sinusoidal pulse-width modulation. The single-phase five-level TCHB inverter simulation model is constructed using MATLAB/Simulink software. In addition, a single-phase conventional H-bridge inverter simulation model using bipolar and unipolar switching schemes, which generates both two levels and three levels of output voltage, is also constructed in MATLAB/Simulink. The total harmonic distortion (THD) results for the two-level, three-level, and five-level inverters are analysed and compared; it is found that the THD for the higher-level inverter is lower. The obtained simulation results are then analysed and discussed. The hardware prototype of the single-phase five-level TCHB inverter is constructed, and analysis is carried out using field programmable gate array (FPGA). The results show that the presented five-level TCHB inverter can produced a sinusoidal output voltage with low harmonic distortion as the amplitude modulation ratio increases.