Study on Improved Double Closed Loop Control Strategy for Urban Rail Inverter Feedback System

In order to improve the response speed during grid connection of inverter system and reliability of grid connected, based on the working principle of regenerative braking energy feedback device, in this paper, the urban rail inverter system is studied, what's more, the output transfer function and stability of the inverter system are analyzed. A double closed-loop control strategy with a hysteresis comparator is designed and applied to the three-phase grid inverter system in this paper, which not only better restrains the resonance spikes but also achieves the bidirectional flow of energy, speeds up the grid response and accelerates to enter the steady state of reverse power operation. At last, the rationality of the strategy is verified by simulating the running condition of the urban rail transit. In addition, the correctness and effectiveness of the control strategy are verified by the low power experimental platform of the grid-connected inverter.