基于载波混合SPWM控制模块化多电平变换器的研究

摘要

模块化多电平变换器(modular multilevel converter,MMC)是柔性直流输电的应用热点之一.针对传统脉冲宽度调制方式在MMC系统中存在使每个模块单元输出功率不等,输出波形性能降低等问题,提出了一种基于载波混合脉冲宽度调制策略(carrier-based hybrid SPWM,CBH-SPWM).该调制策略同时包含了载波重叠和载波移相两种调制方法的特点.一方面提高了输出电压的性能,另一方面使MMC中每个模块输出功率相等.仿真结果验证了所提CBH-SPWM方法的正确性与有效性.%Modular multilevel converter (MMC) is one of the hot spots in the application of Voltage Source Converter based High Voltage Direct Current Transmission (VSC-HVDC).Aiming at the traditional pulse width modulation method in the MMC system,which vary the output power of each module unit and the performance of the output waveform is reduced,a carrier-based hybrid SPWM (CBH-SPWM)is proposed.The modulation strategy includes characteristics of the carrier overlapping modulation and carrier phase shift modulation.On the one hand,the performance of output voltage is improved,on the other hand,output power of each module in the MMC is equal.The correctness and effectiveness of proposed CBH-SPWM was verified through the simulation calculation.