Improved Control for Three-Phase PWM Rectifier Based on Power-Current Model

The dual closed-loop PI control is used for three-phase PWM rectifier, which arises large overshoot voltage and overshoot current in the moment when the PWM rectifier starts running and load changes suddenly. The dual closed-loop PI control is presented based on the voltage-current model for the three-phase PWM rectifier, which illustrated that the DC voltage to the current is in linear relation. The reason why the large overshoot current and voltage occurs in traditional control method is analyzed in theory. On the basis of that the new power-current model is proposed which shows that the square of DC voltage to the current is in linear relation. An improved control strategy is proposed based on the new power-current model. The proposed control method adopted the DC voltage square as the feedback in voltage loop and used current predictive control in current loop. Also, the load current and the DC voltage current feed forward are also employed to improve the performance. Theory analysis show that the proposed control strategy can greatly improve the system dynamic performance and the overshoot voltage and current in starting time and load dynamic changing moment can be greatly decreased. The validity of the proposed methods is proved by the simulation results.