不对称级联九电平逆变器线性功率均衡控制策略  

Linear Power Balance Strategy for Asymmetric Cascaded H-Bridge Nine-Level Inverter

作　　者：叶满园 喻生铭 刘文芳 陈银波 邵云鹏 Ye Manyuan;Yu Shengming;Liu Wenfang;Chen Yinbo;Shao Yunpeng(School of Electrical and Automation Engineering East China Jiaotong University Nanchang 330013,China;State Grid Anhui Electric Power Co.Ltd Huaining County Power Supply Company Anqing 246121,China)

机构地区：[1]华东交通大学电气与自动化工程学院,南昌330013 [2]国网安徽省电力有限公司怀宁县供电公司,安庆246121

出　　处：《电工技术学报》2024年第14期4495-4507,共13页Transactions of China Electrotechnical Society

基　　金：国家自然科学基金资助项目(52267014)。

摘　　要：三单元不对称级联逆变器通常采用传统混合调制策略控制,但该策略下逆变器存在单元间输出功率不均衡以及低压单元开关损耗分配不均的问题,同时由于高低压单元之间输出电压极性不同时会出现电流倒灌,导致逆变器直流侧电压难以维持稳定,影响输出电压波形质量。针对上述问题,该文提出基于功率元重组的混合功率均衡调制策略,该策略对逆变器高压单元采用低频方波调制,在控制单元输出功率大小的同时可以降低开关损耗,而对于低压单元,所提策略结合载波移幅调制和载波移相调制策略对其功率元进行分析重组,使逆变器在输出高质量电压波形的同时实现单元间输出功率的线性均衡和低压单元间开关损耗的均匀分配。最后进行仿真和实验验证。Compared to traditional two-level inverters,cascaded H-bridge(CHB)multi-level inverters based on pulse width modulation(PWM)strategy are widely used in medium and high voltage power applications,such as DC transmission and photovoltaic grid connection,due to their excellent harmonic performance,high efficiency,and low dv/dt.According to different voltage values on the DC side of the inverter,CHB multi-level inverters can be divided into symmetrical and asymmetric cascaded H-bridge multi-level inverters.Asymmetric cascaded inverters output higher voltage levels under the same number of power switches and DC voltage sources,which have high research value.However,the traditional Type II asymmetric CHB inverter has the problem of current reversal under partial amplitude modulation.Therefore,the paper adds a low-voltage unit to the traditional type II asymmetric CHB inverter topology,adjusting the DC side voltage ratio to 2∶1∶1,and effectively avoiding current reversal by selecting switch states at different levels.For the asymmetric cascaded nine-level inverter topology,the traditional hybrid PWM(H-PWM)strategy has the advantage of optimizing the harmonic performance of the output voltage.However,under this modulation strategy,only low-voltage unit H3 operates in the high-frequency state,and high-voltage unit H1 and low-voltage unit H2 both operate in the low-frequency state.The imbalanced output power and uneven distribution of switching losses exist among the cascaded units of the inverter,which seriously affects the lifespan of the inverter topology.Accordingly,the paper proposes an improved hybrid PWM(IH-PWM)modulation strategy based on the H-PWM modulation strategy.The proposed strategy improves the output voltage waveform but does not address the issue of the imbalanced output power between cascaded units.This paper further optimizes the IH-PWM strategy and proposes a hybrid modulation strategy based on power units redistribution(PRH-PWM).For the high-voltage unit H1,the PRH-PWM strategy controls the conduc

关 键 词：不对称级联逆变器 功率元重组 电流倒灌 线性功率均衡 

分 类 号：TM464[电气工程—电器]