单电源自均压九电平逆变器及其调制策略

Single-Source Self-Voltage-Balancing Nine-Level Inverter and Its Modulation Strategy

在分布式可再生能源发电系统中,传统多电平逆变器存在电路结构复杂、功率器件多、控制复杂等缺点。针对上述问题,提出一种基于开关电容结构的单电源均压九电平逆变器,该逆变器由开关电容网络、辅助双向开关以及全桥单元组成。基于开关电容结构的串并联转换工作,所提逆变器能够以较少的功率器件产生更多的输出电平,拓扑结构简单、输出谐波含量低。逆变器电容自均压的优点简化了控制算法,并且单电源输入的特点拓宽了其应用范围。采用特定谐波消除法对逆变器进行调制,进一步减小了输出电压谐波含量,降低了器件的开关频率。最后,通过实验对所提逆变器的稳态及动态工作性能进行验证分析,证明该逆变器及其调制策略的正确性与可行性。

In distributed renewable energy generation systems,traditional multi-level inverters have the disadvantages of too many power devices,complicated circuit structure and control strategy.To solve these problems,a single-source nine-level inverter based on switched capacitor structure is proposed,which consists of switched capacitor network,auxiliary bidirectional switch and H-bridge unit.The proposed inverter can generate more output levels with less power devices,moreover,the topology is simple and has the advantage of low output harmonic content.The advantages of capacitor self-voltage-balancing simplify the control algorithm,and the characteristics of single source can broaden its application range.The specific harmonic elimination method is used to modulate the inverter,which reduces the switching frequency of switches and further reduces the harmonic content of the output voltage.Finally,the steady and dynamic performance of the proposed inverter is verified and analyzed by experiments,which proves the correctness and feasibility of the inverter and its modulation strategy.