Ke Shanwen, Li Yuren
School of Automation, Northwestern Polytechnical University, Xi'an 710129, China.
Sensors (Basel). 2023 Sep 30;23(19):8203. doi: 10.3390/s23198203.
The conventional proportional-gain-feedback link can only obtain the smallest effective damping region (EDR) due to the control delay among all the active damping methods regarding the capacitor current feedback. The digitally controlled system tends to be unstable when the system resonant frequency reaches the critical frequency caused by the grid impedance variation. To weaken the adverse effect on the system caused by the control delay, phase-lead feedback links are applied along the feedback path to provide phase compensation. By taking the simplicity and reliability of the feedback links into account, this paper proposes an alternative to an ideal differentiator, which consists of the Tustin discrete form of '' and a digital low-pass filter. This proposed method has an identical phase frequency characteristic as an ideal differentiator but a better magnitude frequency characteristic, and its EDR can reach [0, /3]. The system stability analysis is conducted under different resonant frequencies, and under the condition of a weak grid, the co-design approach of the active damper and digital controller is presented. Finally, the experimental results are shown to verify the proposed method.
在所有关于电容电流反馈的有源阻尼方法中，由于控制延迟，传统的比例增益反馈环节只能获得最小的有效阻尼区域（EDR）。当系统谐振频率达到由电网阻抗变化引起的临界频率时，数字控制系统往往会变得不稳定。为了削弱控制延迟对系统的不利影响，沿反馈路径应用了相位超前反馈环节以提供相位补偿。考虑到反馈环节的简单性和可靠性，本文提出了一种理想微分器的替代方案，它由“”的Tustin离散形式和一个数字低通滤波器组成。该方法具有与理想微分器相同的相位频率特性，但具有更好的幅度频率特性，其EDR可达[0, /3]。在不同谐振频率下进行了系统稳定性分析，并在弱电网条件下给出了有源阻尼器和数字控制器的协同设计方法。最后，给出了实验结果以验证所提方法。
