摘要
中点箝位型三电平拓扑(3L-NPC)由于其箝位二极管的单向箝位性,易造成桥臂中内外管的电压不均衡,使得内管电压超过半边母线电压,威胁其完全运行。针对该问题,本文对3L-NPC并网逆变器在正常运行、并网待机及故障停机3种典型工况下的内外管不均压机理进行了全面详尽的分析,指出回路中器件杂散参数、内外管结电容的充放电电流不对称、回路LC振荡是造成不均压的主要原因,并据此提出一种简单可靠的解决方案,该方案能够有效抑制各种工况下的内管过压问题,实验结果可验证理论分析的正确性及所提方案的可行性。
Owe to the unidirectional clamping of the clamping diode in three-level neutral-point-c topology, the voltage unbalance between the internal and external devices may occur and the internal exceed the half of the bus voltage which would threaten its full operation. Aiming at this problem, the lamped （3L-NPC） device voltage may mechanisms of the voltage unbalance for the 3L-NPC grid-connected inverter in normal operation, grid-connected standby and shutdown with failure were comprehensively analyzed. The parameters, asymmetric charging and discharging main reasons causing voltage unbalance including device stray currents of the junction capacitance for the internal and external devices and the LC oscillation of the circuit were pointed out. In view of above, a simple and reliable scheme was proposed, which could effectively suppress the over-voltage of the internal device in different conditions. The correctness of theoretical analysis and the feasibility of the proposed scheme were validated by the experimental results.
出处
《太阳能学报》
EI
CAS
CSCD
北大核心
2017年第10期2840-2847,共8页
Acta Energiae Solaris Sinica
基金
"十二五"国家科技支撑计划(2012BAA01B04)
关键词
NPC型三电平逆变器
内外管
电压不均衡
分布参数
充电电流
three-level neutral-point-clamped inverter
internal and external devices
voltage unbalance
distributed parameters
charging current
