采用载波移相调制的模块化多电平换流器损耗一致性分析

阐述了模块化多电平换流器的基本工作原理和损耗数值计算方法,应用PLECS仿真软件针对半桥子模块结构,分析了载波移相调制下不同均压、环流抑制方式下的子模块损耗特性,认为在不影响换流器工作状态的前提下,使用能量均衡法均压以及使用三相解耦二次谐波环流抑制算法进行环流抑制时,各子模块损耗分布一致性更高,整体损耗率更低。通过比较,还发现不同工况下的子模块损耗一致性接近。最后,对比了载波移相调制与最近电平控制调制方式下的损耗一致性,认为载波移相调制下子模块损耗一致性更高。

Loss Consistency Analysis of Modular Multilevel Converter Using Carrier Phase Shifted Sinusoidal Pulse Width Modulation

The modular multilevel converter(MMC)operation mechanism and the numerical method of loss calculation are reviewed. Based on PLECS under carrier phase shifted sinusoidal pulse width modulation(CPS-SPWM), the sub-module loss characteristics are analyzed, including different voltage balancing methods and circulating current suppression methods. Regardless of the status of the converter working performance, the comparison shows that, with the voltage balancing method of energy balance and circulating current suppression method of three phase decoupled second harmonic circulation current suppression, the loss distribution consistency of MMC is higher and the loss rate lower. The loss consistency of different working conditions is similar. Finally, the loss consistency of nearest level control(NLC)is compared with that of CPS-SPWM, and it is shown that with CPS-SPWM the sub-module loss consistency is better. This work is supported by National Natural Science Foundation of China(No.51277065)and National High Technology Research and Development Program of China(863 Program)(No. 2012AA050401).