Modeling and Harmonic Performance of a 12- AC-DC Power Converter with Diode-Clamped Multilevel Inverter for Induction Motor Drives

Abstract This study presents the modelling and harmonic performance analysis of a 12-pulse AC-DC power converter integrated with a five-level diode-clamped multilevel inverter (DCMLI) for high-power induction motor drive applications. It includes system architecture, simulation results, and comparative evaluation against conventional designs. Traditional six-pulse rectifier-based variable frequency drives (VFDs) typically generate significant low-order harmonics—specifically the 5th, 7th, 11th, and 13th, which contribute to poor power factor, voltage distortion, and increased energy consumption. To address these limitations, a 12-pulse DC-AC power converter was developed using phase-shifted transformers to suppress dominant harmonics. Additionally, the DCMLI employs advanced pulse-width modulation (PWM) strategies—namely Phase Disposition (PD), Phase Opposition Disposition (POD), and Alternate Phase Opposition Disposition (APOD) to enhance inverter output quality. Simulation results obtained via MATLAB/Simulink demonstrate that the 12-pulse DC-AC power converter reduces input current total harmonic distortion (THD) from 69.84% (in the six-pulse configuration) to 62.23%, while improving the input power factor from 0.43 to 0.58. Output voltage THD for the DCMLI using APOD PWM is 17.97%, compared to 18.09% and 18.40% for PD and POD techniques, respectively. The proposed system configuration yields smoother motor torque, a 24.73% reduction in rectifier output voltage ripple, and approximately 25% improvement in energy efficiency over the conventional six-pulse drive. Overall, the integration of a 12-pulse rectifier significantly enhances harmonic performance, power factor, and energy efficiency in DCMLI-based induction motor drive systems.