This article proposes a cascaded integral action-based filter by relying on the orthogonal output of a T/4T/4 delay block. The proposed filter employs an integrator together with mechanisms involving feedback of the filtered signal and feedforward of its orthogonal input. Based on this approach, the proposed filter addresses the problem of initial state when applying a direct integral action to a sinusoidal voltage. More so, the proposed filter provides notch filtering characteristics at certain harmonic frequencies, thereby achieving improved harmonic rejection in comparison to existing second-order generalized integrator filter. Without frequency adaptivity, the proposed filter achieves fast response, and more importantly, provides excellent filtering of harmonic components at off-nominal frequencies of the supply voltage. Furthermore, dc-offset rejection in the proposed filter is considered together with its FLL implementation for frequency, phase angle, and amplitude estimations. Linearized model and stability evaluation of the proposed filter’s FLL are presented while detailed analytical, simulation, and experimental validation of the proposed filter’s performance for applications involving voltage parameter estimation for synchronization purposes and reference signal generation are provided. Results obtained demonstrate superiority of the proposed filter in terms of harmonic rejection and estimation speed when compared to existing filtering techniques.

中文翻译：

---

基于级联积分动作的畸变条件过滤器


本文提出了一种基于 T/4T/4 延迟块的正交输出的级联积分动作滤波器。所提出的滤波器采用积分器以及涉及滤波信号的反馈和其正交输入的前馈的机制。基于这种方法，所提出的滤波器解决了对正弦电压应用直接积分作用时的初始状态问题。更重要的是，所提出的滤波器在某些谐波频率处提供陷波滤波特性，从而与现有的二阶广义积分器滤波器相比实现改进的谐波抑制。在没有频率自适应性的情况下，所提出的滤波器实现了快速响应，更重要的是，在电源电压的非标称频率下提供了对谐波分量的出色滤除。此外，还考虑了所提出的滤波器中的直流偏移抑制及其用于频率、相位角和幅度估计的 FLL 实现。提出了所提出的滤波器 FLL 的线性化模型和稳定性评估，同时提供了所提出的滤波器性能的详细分析、仿真和实验验证，这些应用涉及用于同步目的的电压参数估计和参考信号生成。获得的结果证明了与现有滤波技术相比，所提出的滤波器在谐波抑制和估计速度方面的优越性。