单相多电平电流源变流器混合调制与控制技术

Hybrid Modulation and Control Technology of Single Phase Multilevel Current Source Converter

针对较低级联数的多电平电流源变流器,为减小开关损耗和降低谐波分量,引入一种基于低频与高频混合调制策略的单相多电平电流源变流器的拓扑。低频单元由共享直流电流源的m个H桥子模块级联,各子模块平均分配直流源能量,采用最近电平调制;低频单元用来消除最近电平调制单元输出阶梯波中的谐波分量,采用脉宽调制;该方法综合了最近电平调制和脉宽调制的优点。对所提拓扑的工作原理、均流算法及混合调制策略进行了深入分析,并进行相应的仿真和实验验证。仿真和实验结果表明所引入拓扑能显著的降低谐波含量,同时减小开关损耗,由此验证了所提拓扑和控制方法的有效性和可行性。

In order to reduce switching losses and harmonic contents of lower cascade multilevel current source converter, a topology of single-phase multilevel current source inverter based on hybrid low-and high-frequency modulation strategy is proposed. The low-frequency unit is cascaded with m-H bridge sub-modules sharing DC current source, and the DC source energy is evenly distributed to each sub-module, adopting the nearest level modulation（NLM）. The high-frequency unit is used to eliminate harmonic components in output step waveform of low-frequency unit, adopting pulse-width modulation（PWM）. The modulation algorithm combines advantages of NLM and PWM. In this paper, working principle, current sharing algorithm and hybrid modulation strategy of the proposed topology are analyzed. Simulation and experimental verification are carried out with results proving validity and feasibility of the proposed topology and control method.