A Novel Reduced-Order Generalized Differentiator With Zero-Phase Lag and Improved Noise Attenuation

The differentiator is widely used in power converter control to improve the control performance. However, the noise attenuation and phase lag always challenge the digital implementation of the differentiator. The existing differentiators, such as the high-pass filter, nonideal generalized integrator, and the discrete-time optimal control-based tracking differentiator, all face the same incompatible contradiction between noise attenuation and phase lag. The multiple second-order general differentiators lack polarity-selective property and suffer a huge computational burden. To address these issues, this letter proposes a novel reduced-order generalized differentiator (ROGD). Then, different discretization versions of the proposed ROGD and existing differentiators are discussed and compared to demonstrate that the proposed ROGD can achieve excellent performance for differentiation estimation with zero-phase lag and improved noise attenuation at the same time. The effectiveness of the proposed differentiator is finally verified by the differentiator simulation and the experiments of the grid-forming control where the differentiator is used.