To address the stability issues aroused by the negative-resistance effect of constant power loads (CPLs), this article proposes a composite robust discretized quasi-sliding mode control (DQSMC) scheme for stabilization of buck-converter fed dc microgrids with CPLs. In the outer control loop, a robust DQSMC voltage controller is proposed. First, a discrete integral sliding surface is designed to obtain a fast and robust dynamic response of dc-bus voltage. Then, to tackle the varying load disturbances and model uncertainties, a second-order sliding mode disturbance observer is embedded in the voltage controller for disturbance estimation and compensation. The resulting composite DQSMC scheme features enhanced disturbance rejection, inherent chattering suppression, and guaranteed dynamics. Meanwhile, a PI current controller is retained in the inner control loop to realize the current control and limitation. Robustness and stability analysis of the whole composite controller is proved to assure large-signal stability. Simulation and experimental results confirm the superiority of the presented approach.

中文翻译：

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具有恒定功率负载的DC-DC Buck转换器的复合鲁棒拟滑模控制

为了解决由恒定功率负载（CPL）的负电阻效应引起的稳定性问题，本文提出了一种复合稳健的离散化准滑模控制（DQSMC）方案，用于稳定具有CPL的降压转换器馈电直流微电网。在外部控制回路中，提出了一种鲁棒的DQSMC电压控制器。首先，设计了一个离散的整体滑动表面，以获得直流母线电压的快速而稳定的动态响应。然后，为解决变化的负载扰动和模型不确定性，将二阶滑模扰动观测器嵌入电压控制器中，以进行扰动估计和补偿。最终的复合DQSMC方案具有增强的抗干扰能力，固有的颤振抑制能力和保证的动态特性。同时，内部控制回路中保留有PI电流控制器，以实现电流控制和限制。证明了整个复合控制器的鲁棒性和稳定性分析可确保大信号稳定性。仿真和实验结果证实了该方法的优越性。