直流变压器(DC transformer,DCT)是可再生能源直流汇集的关键设备.双主动桥(dual active bridge,DAB)具有双向功率流通特性,可满足海上风电直流汇集等应用需求.面向兆瓦级DCT,基于DAB,该文提出了一种基于集成门极换流晶闸管(integrated gate-commutated thyristor,IGCT)的直流变压器(DC transformer based on IGCT,IGCT-DCT).首先分析了兆瓦级DCT的频率选择;然后综合考虑关断延时、损耗限制以及驱动误差时间,详细分析了均压条件与均流条件,设计了均压RC电路与均流磁环,并且给出了均压电阻、均压电容以及差模电感的计算方法;最后,搭建了一台10 kV/1.5 kV/3 MW的IGCT-DCT样机,验证了所提方案的可行性和理论分析的正确性.所提IGCT-DCT高压侧采用IGCT器件串联技术,低压侧采用IGCT桥臂并联技术,显著提升了 DCT单机容量及功率密度;通过单移相控制,可实现IGCT在大功率下的零电压开通,降低了系统损耗.
Design of High-power DC Transformer Based on IGCT Series and Parallel Connection
DC transformer(DCT)is the key device of a renewable energy generation DC collection system.The dual ac-tive bridge(DAB)has the feature of bidirectional power flow,which is suitable for applications of off-shore windfarm DC collection.For MW DCT,based on DABs,this paper proposes a DC transformer based on IGCT(IGCT-DCT).Firstly,the working frequency of MW DCT is analyzed.And then,considering the turn-off delay,loss limit and the difference of driver delay,the conditions of voltage balancing and current balancing are discussed in detail,therefore,the designs of the voltage-sharing RC circuit and current-sharing magnetic ring are given.Moreover,the calculation methods of voltage equalizing resistor,the voltage equalizing capacitor,and the differential mode inductance are presented.Finally,a 10 kV/1.5 kV 3 MW IGCT-DCT prototype was built to verify the feasibility of the proposed solution and the correctness of the theoretical analysis.The HV side of IGCT-DCT is based on series-connected IGCTs,and the LV side is based on the parallel-connected IGCT bridge arms,thus significantly improving the capacity and power density of the DCT.More-over,by using the single-phase-shift control,the zero-voltage turn-on of IGCT under high power can be achieved,which reduces the system losses.
large-capacity DC transformerIGCT-DCTDABsingle-phase-shift controlzero voltage turn-on
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维普
