A Modified Phase Shift Control of the Dual Active Bridge-Based Modular Power Electronic Transformer to Minimize the LVdc Side Voltage Ripples Under Unbalanced Load Conditions

Power Electronic Transformers (PETs) are considered as an emerging solution for power conversion due to their benefits over the low frequency transformers (LFPTs) such lower size, multi-port structure and different control functionalities. However, unbalanced load conditions may limit reduction of size using bulky capacitors absorb resulting 2nd harmonic voltage oscillations. This paper aims provide a this problem in Dual Active Bridge (DAB)-based Modular Multilevel Converter (MMC-PET). In study, modified phase shift strategy DAB isolation stage is presented. strategy, duty cycle allowed change sinusoidally around operating point. consequently transfers oscillations HV side where effect less significant. The system simulated Matlab-Simulink under conditions. Besides, theoretical analysis simulation results experimentally validated laboratory prototype. According obtained results, proposed controller succeeded reduce ripples from 7.5% 0.2% helps replacing large Aluminum electrolytic with film reducing overall volume which great benefit.