Under dual closed-loop decoupling control

single-phase cascaded H-bridge rectifiers(CHBR)cannot effectively suppress the low-order grid-current harmonics caused by the second-order line-frequency ripple of the DC-bus voltage

thereby deteriorating grid power quality. To address this issue

a proportional-resonant sliding-mode active disturbance rejection control(PR-SM-ADRC)strategy was proposed. First

a mathematical model of the single-phase CHBR was established

and the harmonic components of the CHBR in the dq frame were analyzed. Then

an ADRC-based current-loop controller in the dq frame was designed

in which a quasi-resonant term was introduced into the observer for harmonic suppression

while fractional-order sliding-mode control was incorporated into the state error feedback law to enhance system robustness. The harmonic suppression mechanism of resonant control and the stability of the proposed controller were then theoretically analyzed. Finally

experiments were conducted to validate the proposed PR-SM-ADRC. The results show that the proposed strategy can effectively suppress grid-side harmonics

reducing THD by 24.2% compared with conventional suppression methods. Meanwhile

the dynamic performance is improved significantly

with the settling time under load step changes shortened by 49.7% and that under reference-voltage step changes shortened by 25.9%.