Comparative Analysis of Current and Voltage THD at Different Grid Powers for Powerful Active Front-End Rectifiers with Preprogrammed PWM

Preprogrammed pulse width modulation (PPWM) techniques are drawing a great deal of interest due to their strong harmonic performance. However, there have not yet been any systematic studies or elaboration of the influence of different grid powers on current and voltage THD using PPWM. Therefore, this article focuses on a comparative analysis of current and voltage THD in a system with a three-phase, three-level active front-end (AFE) at different grid powers by applying PPWM. A six-pulse electric drive power circuit and one laboratory measurement platform were designed and set up to achieve the above goals. The comparative results were calculated up to the 50th (THD50) and 100th (THD100) harmonics against the frequency of the PPWM, ranging between 150 Hz and 750 Hz. The grid power and AFE power ratio was between 30 and 230 under three different AFE-consumed currents. The experimental results were analyzed and compared, and they demonstrated for the first time how the grid power and AFE power ratio with different PPWM patterns can influence current and voltage THD. The research results suggest that it is necessary to review the existing calculation methods for current and voltage THD using modern electric power quality standards. The results presented in this article also provide a reference point for researchers and engineers when considering the electromagnetic compatibility (EMC) of nonlinear consumers in the design of similar circuits.