中文摘要：

模块化多电平矩阵变换器（MMMC）在低频甚至零频率运行时,低频纹波电压与输出频率成反比,导致模块电容电压波动过大而影响MMMC安全运行。为解决该问题,提出一种MMMC低频控制方法。该方法外环采用层次化电容电压平衡控制,并基于能量交换规律将输出二倍频纹波电压当做有用成分,与电容电压直流分量共同参与平衡控制,最后,通过复合控制器实现MMMC相间平衡和低频纹波抑制的双重控制;内环采用各桥臂电流独立控制,避免了复杂的解耦变换和内部环流产生。该方法适用于输出零频率的特例工况。通过半实物实验验证了所提控制方案的可行性、有效性以及优良的动静态特性。

英文摘要：

When a modular multilevel matrix converter（MMMC）is operated at a low or even zero frequency,the operation security of switching devices and sub-module capacitors will be threatened as the peak value of the main component of submodule capacitors ripple voltage is inversely proportional to the output frequency.To solve this problem,this paper presents a low-frequency control scheme of MMMC.The balance of the sub-module capacitor voltage is achieved by hierarchical control in the outer loop.As useful components based on the rules of energy exchange,the doubling output frequency ripple voltage participates in the balancing control together with the DC components of capacitor voltage.Finally,the dual control of interphases balancing and ripple suppression is achieved by the unified hybrid controller.Moreover,the inner loop of the scheme adopts the arm current independent control,avoiding the occurrence of complicated vector transform and inner circulating currents.The scheme is suitable for special operation with zero output frequency.Eventually,the hardware-in-theloop experiment system has successfully verified the feasibility and validity of the scheme.