Modified Model Predictive Control for the Aerospace PWM Rectifiers

This paper proposes a modified finite control set model predictive control method (FCS-MPC) for three-phase PWM aerospace rectifiers. According to the operating conditions in aircraft variable frequency alternating current (VFAC) electrical power system, the power flow in ac side is analyzed. The proposed control method is based on the discrete-time model of rectifiers and does not require additional PWM modulators. It is noticed that the controlling performance of MPC is affected seriously by the number of points in each sampling period duo to the variation of main frequency, which is changed from 360- 800Hz in the aircraft electrical power system, to solve the problem, the linear extrapolation method is derived with the traditional FCS-MPC. Based on this method, the controlling time sequences must be chosen properly. The derived points from the extrapolation algorithm can be used to calculate the predictive power of MPC. So the performance of MPC can be improved by adding the predictive points during one cycle. The simulation and experimental results show that under balanced three-phase aeronautical alternating power supply, the accurate tracking function for the reference of the output voltage and reactive power can be achieved with the proposed MPC method.