An Active Disturbance Rejection Control-Based Voltage Control Strategy of Single-Phase Cascaded H-Bridge Rectifiers

In the traditional control strategy for single-phase PWM converter applications, the proportional-integral (PI) controller has the role of voltage tracking in the outer loop voltage controller, which has limited capability to provide acceptable dynamic performance and disturbance rejection. With regard to this, this article proposes a voltage control strategy based on the active disturbance rejection control (ADRC) for single-phase cascaded H-bridge rectifiers, aiming at achieving satisfactory dynamic performance and strong robustness to the disturbances. First, the extended state observer is used for the state and disturbance estimations. Then, the nonlinear state error feedback deals with the system error and makes the dynamic compensation to the disturbances. More specifically, an improved continuous nonlinear function is adopted to mitigate the jitter behavior of the traditional ADRC and provide immunity to large disturbance errors. Furthermore, the performance and stability analysis of the proposed strategy are implemented. A parameter tuning guideline of the proposed strategy is detailed. The effectiveness of the proposed ADRC-based voltage control strategy is verified through extensive experimental tests and is compared to that of the conventional PI-based voltage control strategy.