Observer-Based Active Disturbance Rejection Control for Fraction-Delay Grid-Tied Inverters

Aiming at damping high-frequency resonances, the pulse-width modulation strategy characterized by reduced control delay is gaining attention in grid-tied inverter. However, the outcome of the fractional ratio of the sampling-computation period to the control period challenges the discrete-time state-space modeling and the control implementation. Therefore, a delay-based input matrix is proposed for discretizing the fraction-delay system, which further facilitates the application of active disturbance rejection control. The observer is also exemplified by introducing a feedback of the error of the observable state, which avoids using extra sensors. Finally, experiments are conducted on a grid-tied inverter to corroborate the effectiveness of the model and the modern control method.