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Transportation electrification involves the wide utilization of power electronics based DC distribution networks and the integration of a large amount of power electronic loads. These power electronic loads, when tightly controlled, behave as constant power loads (CPLs) and may cause system instability when interacting with their source converters. In this paper, a composite nonlinear controller is proposed for stabilizing DC/DC boost converter feeding CPLs by integrating a nonlinear disturbance observer (NDO) based feedforward compensation with backstepping design algorithm. First, the model is transformed into the Brunovsky's canonical form using the exact feedback linearization technique, to handle the nonlinearity introduced by the CPL. Second, the NDO technique is adopted to estimate the load power variation within a fast dynamic response, serving as a feedforward compensation to increase the accuracy of output voltage regulation. Then a nonlinear controller is developed by following the step-by-step backstepping algorithm with strictly guaranteed large signal stability. The proposed controller not only ensures global stability under large variation of the CPL, but also features fast dynamic response with accurate tracking over wide operating range. Both simulations and experiments are conducted to verify the proposed strategy.

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24 25 Zircon U-Pb ages and geochemical data are reported for the Piqiang oxide-bearing 26 ultramfic-mafic complex, the Bachu mafic dyke swarm, the Yingan and Kaipaizileike basalts 27 and the Halajun A-type granites in the Tarim Block, Northwest China. The Piqiang complex 28 and the Halajun A-type granites were emplaced at ca. 276 Ma and ca. 278 Ma, respectively. 29 Together with previously reported geochronological data, the diverse intrusive and extrusive 30 rocks in Tarim show a peak age at ca. 275 Ma. Elemental and Nd isotope geochemistry 31 suggests that the spatially and temporally related Piqiang complex (including some dolerite 32 dykes or stocks) and the Halajun A-type granites were formed via crystal 33 fractionation/accumulation of a common plume-derived parental mafic magma (melting 34 degree > 10%), coupled with variable extents of crustal contamination. Crystal 35 fractionation/accumulation in one or several magma chambers resulted in the diversity of 36 rocks types. The Bachu mafic dyke swarm shares a similar mantle source with the intrusive 37 rocks in the Piqiang-Halajun area but with a relatively lower degree of partial melting (~5%). 38 In contrast, the basalts were derived from a time-integrated, enriched lithospheric mantle 39 source as suggested by their high-Ti, LREE-and LILE-enriched trace element signature and 40 negative ε Nd (T) values (-2.0 ~ -2.6). The synchronous yet diverse range of Permian igneous 41 rocks in Tarim can best be accounted for by a Permian mantle plume, which is about 15 Ma 42 earlier than the Emeishan plume in southwestern China. 43