A novel PWM technique to eliminate common-mode voltage for single-phase three-level T-NPC inverter

Abstract

This paper presents a new pulse width modulation (PWM) technique in order to eliminate common mode voltage for a single-phase full H-bridge T-NPC inverter. Three-level NPC inverters are commonly used in grid connected applications or as UPS backup power for industry. In addition to abilities such as to withstand high voltage, and reach output voltage and current with low harmonic distortion, three-level NPC inverter is advantageous for mitigating common mode voltage and leakage current. The new proposed PWM technique is based on the switching state table of the three-level H-bridge T-NPC inverter that containing many switching states with zero common mode voltage. Furthermore, implementation of PWM control for single-phase three-level T-NPC inverter configuration can decrease voltage stress on the output and reduce output voltage distortion compared with bipolar PWM control technique for two-level H-bridge inverter. In this paper, the sine wave carrier PWM technique is analyzed, designed and modelled based on the switching table. The analytical analysis will be evaluated using MATLAB/SIMULINK. Simulation results of the proposed PWM technique for three-level T-NPC inverter are compared with conventional techniques without common mode voltage elimination; the quality of the three-level T-NPC inverter is also compared to that of traditional two-level inverter. The power loss content is evaluated using PLECS software. The obtained results confirm the advantages of the eliminated common mode voltage PWM technique in the three-level T-NPC inverter configuration.