混合级联多电平逆变器混合频率调制策略的研究

Research on Mixed-frequency Modulation Strategy for Hybrid Cascaded Multi-level Inverter

针对混合级联H桥多电平逆变器传统混合频率调制策略产生的电流倒灌和能量反馈问题,本文提出了一种基于载波层叠的混合频率优化调制策略,其中,高压单元采用正负反向层叠的方法,低压单元采用一种类似单极倍频的方法。对比较所得脉冲进行了重新的逻辑运算与组合,不仅有效解决了传统混合调制所产生的电流倒灌和能量反馈的问题,而且改善了混合频率调制下高压单元输出电压波形的谐波特性,从而降低了混合级联H桥多电平逆变器输出电压低次谐波的含量,提高了逆变器输出电能的质量。最后,搭建了Matlab/Simulink仿真模型和实验平台,仿真和实验研究验证了该调制策略的有效性和切实性。

Aiming at the problem of current inrush and energy feedback caused by the traditional mixed-frequency modulation strategy for a hybrid cascaded H-bridge multi-level inverter,a mixed-frequency optimization modulation strategy based on carrier cascade is proposed,in which the high-voltage unit adopts positive and negative reversal while the low-voltage unit adopts a method similar to the single-pole frequency doubling. In addition,the logical operations and combinations of the compared pulses are conducted. As a result,the problem of current inrush and energy feedback caused by the traditional hybrid modulation is effectively resolved,and the harmonic characteristics of output voltage waveform from the high-voltage unit under the mixed-frequency modulation are also improved,thereby reducing the content of low-order harmonic in the output voltage from the hybrid cascaded H-bridge multi-level inverter and improving the quality of output power from the inverter. Finally,a simulation model and an experimental platform were built using Matlab/Simulink,and simulation and experimental results verified the validity and practicality of the proposed modulation strategy.