一种基于环流注入的全桥型MMC降容优化设计

Derating Optimal Design of Full⁃bridge MMC Based on Circulating Current Injection

为降低全桥型MMC各子模块电容体积,提高全桥型MMC功率密度,基于调制比和环流对电容电压波动影响机理,提出一种特定相位及幅值环流注入的方法,降低了各子模块滤波电容电压波动。为验证所提方法的正确性,在额定工况及单位功率因数条件下,对所提方法进行了仿真实验,仿真结果表明,采用新的降容措施后,电容电压波动范围缩小20%,纹波系数减小至30%,电容容量减小20%。

For reducing the capacitor volume of each sub⁃module and increasing the power density of the full⁃bridge MMC,a kind of circulating current injection method with specific phase and amplitude is proposed on the basis of the mechanism of modulation ratio and circulating current on the capacitor voltage fluctuation,which reduces the voltage fluctuation of filter capacitor of each sub⁃module.For verifying the correctness of the proposed method,the simulation experiment of the proposed method is performed at rated condition and unit power factor.The simulation results show that after adopting the new derating measures,the fluctuation range of the capacitor voltage is reduced by 20%,and the ripple coefficient is reduced by 30%,and the capacitance of the capacitor is reduced by 20%.