【目的】碳化硅(SiC)器件因其低开关损耗、高耐压等优异特性，在中压领域的模块化多电平换流器(MMC)应用中具有显著优势。但基于SiC器件的子模块在开关瞬态会产生高du/dt、di/dt，造成严重的电磁干扰，危害系统安全。【方法】为了解决该问题，本文根据MMC拓扑特点分析了子模块杂散电容分布特性，通过对杂散电容的等效变换，构建了共模干扰电流等效电路模型。在此基础上，提出一种基于载波移相脉冲宽度调制的上下桥臂位置互补子模块触发脉冲耦合方法，通过调整位置互补子模块的载波相位实现对共模电流的抑制。【结果】仿真结果表明，所提出的方法能够有效维持子模块电容电压平衡并确保交流侧输出波形质量，这两项指标均是衡量MMC性能的关键参数。与传统方法相比，该策略将共模电流峰值抑制了43%，展现出更优的抑制性能，验证了该方法的有效性。【结论】所提出的方法可有效抑制共模干扰电流，从而显著提升SiC MMC的整体性能与可靠性。该研究成果为碳化硅器件在中压电力电子系统中的技术发展提供了重要参考价值。

[Objective] Silicon carbide (SiC) devices, characterized by low switching losses and high voltage endurance, demonstrate significant advantages in modular multilevel converter (MMC) for medium-voltage applications. However, submodules based on SiC devices generate high du/dt and di/dt during switching transients, leading to severe electromagnetic interference that compromises system safety. [Methods] To address this issue, this study analyzed the stray capacitance distribution characteristics of submodules based on the MMC topology. By performing an equivalent transformation of stray capacitance, an equivalent circuit model for common-mode interference was established. On this basis, a novel common-mode current suppression strategy was proposed, employing carrier phase-shifted pulse width modulation with complementary submodules triggering pulses in the upper and lower bridge arms. By adjusting the carrier phase of the complementary submodules, common-mode current suppression was achieved. [Results] Simulation results showed that the proposed method effectively maintained submodules capacitor voltage balance and ensured high-quality AC-side output waveforms, both of which were critical performance factors for MMC. Compared to conventional methods, the proposed strategy reduced the peak common-mode current by 43%, demonstrating better suppression capability and validating its effectiveness. [Conclusion] The proposed method effectively suppresses common-mode interference current, enhancing the overall integrity and reliability of SiC MMC. These findings provide valuable insights into the advancement of power electronics technology in medium-voltage applications.

湖南省自然科学基金(2022JJ40150);国网总部科技项目(52272810005)