An Improved MPC Scheme with Fast DC-Bus Voltage Regulation for Traction Converters in High-Speed Trains

For the ac/dc converters in high-speed trains, the dead-beat model predictive control (MPC) method is constantly used for the current loop, and the proportional-integral (PI) control method is used for the voltage loop. The PI controller, however, limits the dynamic performance of the converter by making it respond slowly to variations in output power. To solve this problem, this paper proposes an improved MPC method that accounts for both voltage and current loops, with the fast dc-bus voltage regulation speed. Firstly, the discretization equation of the dc-bus voltage is established, and the cost function of the voltage loop is designed by the current loop. Then, for superior steady-state performance, an integral compensation of the dc-bus voltage is added. Further, to avoid adding additional sensors, the estimation method of the dc-bus current is designed. Finally, the proposed MPC method is tested on a scale-down experimental platform. Experimental results have verified that the proposed MPC method can achieve the superior dynamic and steady-state performance.