A Single-Phase Nine-Level Bridge Inverter Employing Level-Shifted Carrier PWM for Low-Voltage Applications

In this paper, a new Nine-Level Single-Phase Bridge Inverter (NLSPBI) with a reduced number of switches using Level-Shifted Carrier Pulse Width Modulation (LSCPWM) is presented. Unlike other DC supply sequences, the proposed topology provides a higher voltage level by requiring a minimum group of components and DC input sources for the supply as it uses trinary series DC sources (1:3). Adding and removing DC input sources in this trinary arrangement results in higher output levels. The trinary supply-fed multilevel concept is implemented in a nine-level inverter with seven power switches and two power diodes. A maximum of four devices can be operated at any one time, operating only two power switches simultaneously with a high frequency, which significantly reduces switching and line losses, thereby increasing the overall system's efficiency. In addition, a level-shifted carrier PWM with Phase Disposition (PD) and an Alternative Phase Opposition (APO) PWM are proposed to optimize the output level and improve the harmonic spectrum. The computation of the power loss for the proposed configuration is described in detail using relevant mathematical formulas. Furthermore, by using MATLAB/Simulink and Hardware-In-The-Loop (HIL) simulations, it has been demonstrated that the presented inverter structure is feasible with the proposed PWM scheme and can provide the desired performance.