Control method for suppressing DC side voltage fluctuation of current-source PWM rectifier

When the load of three-phase current source pulse width modulation rectifier suddenly changes, it will cause the output voltage fluctuation on the DC side. To address this issue, an integrated control strategy of active disturbance rejection control and deadbeat predictive control cascade is proposed. Firstly, the discrete mathematical model of rectifier in the two-phase static coordinate system is formulated, and deadbeat control strategy is introduced into current inner loop to realize fast tracking of grid-side current. To reduce the influence of control delay, the control algorithm is predicted to time k+2 and the current at time k+1 is eliminated by arithmetic iteration process. Thus, the control accuracy of grid-side current and reducing the harmonic content of current is improved. In addition, the active disturbance rejection control is introduced into the outer loop to control the DC output voltage, and the disturbance of the system is estimated and compensated in real time by the extended state observer, which overcomes the problems of insufficient parameter control margin and poor anti-interference ability of the traditional proportional integral controller. Finally, the proposed control strategy is evaluated by MATLAB/ Simulink software and 6 kW experimental prototype. The results show that the output voltage fluctuation can be effectively suppressed within 22 V when the system load suddenly increases or decreases, and the total harmonic distortion rate of the grid-side current is guaranteed to be as low as 1. 98% under full load operation. © 2023 Science Press. All rights reserved.