Fractional-Order Linear Active Disturbance Rejection Control Strategy for Grid-Side Current of PWM Rectifiers

To further improve the performance of linear extended state observer (LESO), a novel fractional-order LESO (FOLESO) is proposed in this article. By incorporating a fractional-order term into the framework of traditional LESO, the design of FOLESO is more flexible, and thereby, the disturbance estimation error can be further reduced. Based on the proposed FOLESO, a fractional-order linear active disturbance rejection control (FOLADRC) strategy has been designed for grid-side current control of three-phase voltage-type pulsewidth modulation (PWM) rectifiers. In this way, the harmonic suppression property can be enhanced without sacrificing the tracking performance, and the ideal grid-side current can be achieved. Furthermore, the detailed design process, implementation mode, and parameter tuning of FOLADRC are also given in this article. The theoretical analysis and experimental results show that the proposed method is effective and superior to the traditional PI control or linear active disturbance rejection control (LADRC) strategy.