Novel Frequency-Doubling Modulation and Control Strategy for Three-Level Full Bridge based Power Electronic Traction TransformersHongbo Li, Wenqing Mei, Ye Yang, Wenguang Luo, Zhixue Zhang and Xiaodi ZangE3S Web Conf., 115 (2019) 01005DOI: https://doi.org/10.1051/e3sconf/201911501005