电力电子牵引变压器PETT(Power Electronic Traction Transformer)与传统工频牵引变压器相比具有体积小、质量轻、效率高等优点.针对采用级联H桥和双有源桥式DAB(Dual Active Bridge)变换器的PETT主电路拓扑,首先对级联H桥进行数学建模分析,在此基础上,提出一种基于平均电压调节的直流电压平衡控制方法.同时,通过分析并联输出DAB变换器传输功率不平衡的影响因素,得出其功率平衡原理,进而提出一种基于平均输出电流调节的均流控制方法.构建PETT系统仿真模型,对所提出的级联H桥直流电压平衡控制方法以及并联输出DAB变换器均流控制方法进行仿真研究.设计并搭建2个功率单元组成的PETT实验平台,对上述控制方法进行实验研究.仿真和实验结果相符,验证所提出控制方法的有效性和正确性.%Compared with the conventional power frequency traction transformer,the power electronic traction transformer(PETT) has the advantages such as small size,light weight and high efficiency.In response to the PETT main circuit topology with cascaded H-bridge and dual active bridge(DAB) converters,a mathematical model for cascade H bridge was first built.On the basis of the model,a DC voltage balance control method based on average voltage regulation was proposed.Meanwhile,by analyzing the influencing factors of the unbalanced transmission power between the paralleled DAB converters,the power balance principle was obtained and the current sharing control strategy based on the average output current regulation was further proposed.The simulation model of the PETT system was built,to simulate the proposed DC voltage balance control method of the cascaded H-bridge converter and the current sharing control strategy of the parallel output DAB converters.In order to verify the effectiveness of the proposed schemes,a test platform for the PETT composed of two power units was designed and built.The experimental results were consistent with the simulation results,verifying the effectiveness and correctness of the proposed control methods.
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