【目的】本文提出一种基于直接功率控制结构的分数阶滑模控制(FOSMC)方法,以抑制电网不平衡工况下三相PWM整流器并网电流畸变和直流电压波动问题。【方法】首先,在两相静止坐标系下建立三相PWM整流器在电网不平衡工况下直接功率控制动态模型,无需锁相环和电流环,简化系统结构。基于此模型,通过修正功率参考值将电网不平衡工况下的控制目标转化为功率跟踪问题。然后,在功率内环构造FOSMC控制器,通过引入分数阶项增加了设计自由度,在有效缓解滑模抖振现象的同时快速精准跟踪功率参考值。在直流外环中设计基于反双曲正弦函数的扩张状态观测器,利用其光滑连续特性,实现对直流侧负载扰动的实时估计;同时,结合FOSMC定律,构造电压外环控制器,保障了负载扰动下的直流电压控制性能。【结果】理论分析和测试结果验证了所提方法的有效性。【结论】在电网不平衡工况下实现了快速精准功率跟踪和直流电压调节,有效抑制了并网电流畸变和直流电压波动,显著提升了系统对负载扰动的抗干扰能力,为三相PWM整流器在不平衡电网条件下的高性能控制提供了有效方案。

[Objective] This paper proposes a fractional-order sliding mode control (FOSMC) method based on the direct power control structure, to suppress the grid-current distortion and DC voltage fluctuations of the three-phase PWM rectifier under unbalanced grid conditions. [Methods] Firstly, a dynamic model for the direct power control of the three-phase PWM rectifier under unbalanced grid conditions was established in the two-phase stationary coordinate system, eliminating the need for phase-locked loops and current loops, which simplifies the system structure. Based on this model, the control objective under unbalanced conditions was transformed into a power tracking problem by correcting the power references. Subsequently, a FOSMC power controller was constructed for the inner power loop. The introduction of the fractional-order term increased design flexibility, effectively mitigating sliding mode chattering while ensuring rapid and precise tracking of the power references. Furthermore, an extended state observer based on the inverse hyperbolic sine function was designed for the outer DC voltage loop. Leveraging its smooth and continuous characteristics, real-time estimation of DC-side load disturbances was achieved. Finally, by integrating this with the FOSMC law, the voltage outer-loop controller was formulated, guaranteeing robust DC voltage control performance even under load disturbances. [Results] The effectiveness of the proposed FOSMC method was validated by theoretical analysis and test results. [Conclusion] The proposed method achieves rapid and precise power tracking and DC voltage regulation under unbalanced grid conditions, effectively suppressing grid-current distortion and DC voltage fluctuations. It significantly enhances the system’s disturbance rejection capability, providing an effective solution for the high-performance control of three-phase PWM rectifiers in unbalanced grid scenarios.

国家自然科学基金(62503261)；中国博士后科学基金面上资助项目(2025M781644)；山东省高等学校青创科技支持计划(2025KJH133)