扩展模块化多电平矩阵变换器低频运行范围的控制方法

模块化多电平矩阵变换器(M~3C)电容电压各频率纹波幅值与对应频率成反比。当M~3C低频率连续运行至输出/输入频率比接近1/3时,差频(输入频率与输出三倍频之差)电容电压波动幅值趋于无穷大,导致M~3C难以正常运行,也阻断了输出二倍频纹波电压的连续抑制。提出一种基于电容电压分层解耦控制和桥臂电流独立控制的M~3C控制方案,电压外环通过直接反馈控制输出相间的输出二倍频纹波电压(或瞬时功率),并闭环实现电流指令重构,消除了1/3频率比及其附近的不连续工作点,提高了M~3C低频率连续运行的频率范围。最后通过半实物实验验证了该方法的有效性。

Control Scheme of Modular Multilevel Matrix Converters for Expanding Low-frequency Operating Range

The amplitude of each frequency component of sub-module capacitors ripple voltages is inversely proportional to its frequency in modular multilevel matrix converters(M3C). When the output-input frequency ratio approaches 1/3 under the low-frequency operating conditions, M3C will hardly work properly on account of too high a ripple voltage amplitude of difference frequency between the input frequency and triple output frequency, blocking the continuous suppression of doubling output frequency ripple voltage. This paper presents a control scheme based on the decoupled hierarchical capacitors voltages control and arm current independent control. The doubling output frequency ripple voltage instantaneous power is directly controlled by the outer loop feedback. The continuous operating frequency range is expanded because of the elimination of discontinuous points nearby or the frequency ratio 1/3 by means of current reconstruction. Finally, the OPAL-Rtlab experiments results have verified the control scheme. This work is supported by National Natural Science Foundation of China(No. 51541708).