蔡智林　侯涛

摘 要： 针对传统Z源逆变器升压能力不足，电容电压应力较高，输入电流断续，高电压增益时直流链电压利用率较低等问题，提出一种新型高增益准Z源逆变器拓扑。该拓扑结构通过在传统Z源网络中串入升压单元，并引入2个电容和2个电感，提高了升压能力和直流链电压利用率，并拓宽了调制比范围。在相同电压增益条件下，相比传统Z源逆变器，有效降低了电容电压应力；直通占空比更小，可降低系统直通状态时的导通损耗，实现了输入电流连续。升压单元级联越多，升压能力越强，调制比范围越宽，电压利用率越高，电容电压应力越低。在Matlab中进行了大量仿真研究，结果证明所提新型拓扑的正确性与有效性。

关键词： 高增益Z源逆变器； 电容电压； 升压单元； 级联单元

中图分类号： TN61?34； TM464 文献标识码： A 文章编号： 1004?373X（2016）24?0149?05

A new high?gain quasi Z?source inverter

CAI Zhilin， HOU Tao

（School of Automation and Electrical Engineering， Lanzhou Jiaotong University， Lanzhou 730070， China）

Abstract： Since the traditional Z?source inverter has the problems of insufficient voltage boost ability， high capacitor voltage stress， discontinuous input current， and low DC link voltage utilization ratio under the condition of the high?voltage gain， a new high?gain quasi Z?source inverter topology is proposed. The boost unit is cascaded in the Z?source network， and two capacitors and two inductances are introduced in the topology structure. This topology can improve the boost ability and DC link voltage utilization ratio， and widen the modulation ratio. In comparison with the traditional Z?source inverter， this inverter can reduce the capacitor voltage stress effectively under the condition of the same voltage gain. The smaller shoot?through duty ratio can reduce the breakover loss of the shoot?through state， and realize the continuity of input current. The more the boost voltage cascade units are imported， the better the boost capability becomes； the wider the modulation ratio is， the higher the voltage utilization ratio becomes， and the lower the capacitor voltage stress becomes. A lot of simulation studies are carried out in Matlab， and the results prove that the new topology is correct and valid.

Keywords： high?gain Z?source inverter； capacitor voltage； boost unit； cascade unit

0 引 言

Z源逆变器以其独特的阻抗源网络，有效实现了升降压变换，弥补了传统电压源与电流源逆变器输出交流电压只能小于输入直流电压的不足[1?2]。将其应用在光伏发电，风力发电等新能源领域，可省去直流升压电路，效率更高，得到了广泛研究[3?5]。但传统Z源逆变器升压能力不足，电容电压应力较高，由于直通占空比与调制比的制约关系，在需要较高的电压增益时，不得不减小调制比以获得较大的直通占空比，这同时造成了直流链电压利用率降低[6?7]。因此，改进Z源网络，以提高升压能力，降低电容电压应力，提高直流链电压利用率是Z源逆变器的主要研究方向[7?9]。……