新型Z源T型五电平逆变器及其调制策略

Novel Z-source T-type Five-level Inverter and Its Modulation Strategy

针对传统二极管中点钳位三电平与五电平逆变器需要大量钳位二极管、结构复杂、可靠性差、二极管开关损耗较大,以及传统Z源两电平逆变器电容电压应力较高、升压能力不足、功率较低等问题。首先,提出了一种T型五电平逆变器拓扑,该拓扑省去了大量钳位二极管,结构简单,开关损耗小,功率等级高;其次,结合Z源网络与该T型五电平拓扑,得到一种新型Z源T型五电平逆变器拓扑,与传统Z源逆变器相比,在相同的电压增益下,该新型逆变器有效降低了开关器件电压与电容电压;再次,将Z源网络中的电感用升压单元代替,进一步增强了其升压能力;最后,设计了该新型逆变器的同向载波调制策略。仿真实验证明了所提拓扑的正确性与调制策略的有效性。

In view of the problems that the traditional diode neutral-point-clamped three-level and five-level inverters require a large number of clamping diodes, complex structure, poor reliability, high switching losses, and capacitor voltage of the traditional Z-source two-level inverter is high, its boost capacity is insufficient, output power is lower, this paper puts forward a new T-type five-level inverter topology. This new topology saves the clamping diodes, simplifies the structure, reduces the switching losses and improves its power level. Secondly, combining the Z-source network and the T-type five-level inverter, we gets a new Z-source T-type five-level inverter; the new inverter reduces the switching device voltage and capacitor voltage effectively at the same voltage gain. Then, its boost capacity gets higher by replacing the inductors of Z-source network with boost units. Finally, we design the modulation strategy with the same direction carrier of the new inverter. The simulation results prove the correctness of the proposed topologies and the effectiveness of the modulation strategy.