Research on feedforward control of four-quadrant converter based on load current observer

In the field of heavy-duty transportation of electric locomotives, the power of traction converters can reach MW, but the switching frequency needs to be kept at several hundred Hz. In addition, the converter needs to maintain a high transient response to load changes and keep grid-side harmonics at a low level, which is difficult to meet simultaneously. More critically, load disturbances often occur in electric locomotives during operation, which may lead to DC voltage pulsations and more serious overvoltage faults, which in turn lead to an increase in grid harmonics and a reduction in the stability of the traction system. To address the above challenges, this paper proposes a state observer-based power feedforward control method for high-power locomotives, which helps to improve the dynamic performance of the converter while minimizing harmonics to the grid, thus achieving more stable operation of the traction system. Finally, the feasibility and effectiveness of the proposed method are verified by simulations and multi-condition experiments on a 1.2MW electric traction platform.