Feedback Linearization-Based Current Control Strategy for Modular Multilevel Converters
Feedback Linearization-Based Current Control Strategy for Modular Multilevel Converters
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DOI：
10.1109/tpel.2017.2662062
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发表时间：
2018-01
影响因子：
6.7
通讯作者：
Peng Wang;Yi Tang
中科院分区：
文献类型：
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作者：
Peng Wang;Yi Tang
模块化多电平换流器（MMC）是多输入多输出（MIMO）非线性系统。MMC的控制系统需要同时实现多个控制目标，例如输出电流调节、子模块电容电压控制以及环流抑制。现有的MMC级联控制策略通过相对复杂的控制器来实现这些控制目标，并且对于这种具有高度耦合状态的非线性系统，控制器参数设计通常很困难。鉴于此，本文针对MMC系统提出了一种基于反馈线性化的电流控制策略。给出了MMC的非线性状态函数模型，并借助输入 - 输出反馈线性化技术将其转换为线性化和解耦的形式。基于线性化系统，采用简单的线性控制器来调节MMC的输出电流和内部差模电流，这大大降低了控制器设计的难度。分析了所提控制策略的稳定性。实验验证结果表明，与传统的MMC级联控制策略相比，所提反馈线性化控制策略能够实现更好的稳态和动态性能。通过实验研究了所提控制策略针对参数不确定性的鲁棒性。
Modular multilevel converters (MMCs) are multi-input multi-output (MIMO) nonlinear systems. The control systems for MMCs are required to simultaneously achieve multiple control objectives, e.g., output current regulation, submodule capacitor voltage control, and circulating ripple currents suppression. Existing cascaded control strategies for MMCs achieve those control objectives with relatively complex controllers, and the controller parameter design is normally difficult for such nonlinear systems with highly coupled states. In view of this, a feedback linearization-based current control strategy is proposed for an MMC system in this paper. The nonlinear state function model of the MMC is presented and transformed to a linearized and decoupled form with the help of the input–output feedback linearization technique. Based on the linearized system, simple linear controllers are employed to regulate the output and inner differential currents of the MMC, which significantly reduces the difficulty in controller design. The stability of the proposed control strategy is analyzed. The experimental verification results show that, compared to the conventional cascaded control strategies for MMCs, the proposed feedback linearization control strategy is able to achieve improved steady-state and dynamic performances. The robustness of the proposed control strategy against parametric uncertainties is experimentally investigated.