LAUSR

Abstract The cascaded delayed signal cancellation (CDSC) based PLL in dq rotate frame ( dq CDSC-PLL) can totally eliminate the disturbances of phase error. However, its open-loop bandwidth is significantly affected after incorporating CDSC into the PLL structure, so the transient response performance of three dq CDSC-PLLs are deteriorated. This paper proposes an improved dq CDSC-PLL by cascading a digital filter based phase-lead compensator into CDSC-based PLL to improve the dynamic response without sacrificing the stability. The filter shows flat gain in the passband, which can compensate the phase delay induced by CDSC and simultaneously maintain the attenuation of the notch point. The improved dq CDSC-PLLs significantly increases the open-loop bandwidth and enhances the dynamic performance. Besides, in order to further minimize the undesirable steady-state error, the frequency adaptive control was adopted without using any additional circuits. In order to verify the effectiveness of the proposed method, the simulation based on Matlab/Simulink is carried out for various conditions. Furthermore, experimental results for typical scenarios are provided, which highlight the advantage of the improved dq CDSC-PLL in terms of the dynamic performance.