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Power electronic transformers (PETs) have high voltage isolation requirements and a large number of modules, which requires the auxiliary power supply (APS) to achieve high voltage isolation and multiple outputs. This paper proposes a parameter optimization method for the current source APS applied to PETs, enabling the APS to have multiple output voltage self-regulation capabilities. By optimizing the excitation inductance and leakage inductance for the current transformer of the APS, the excitation current plays a regulating role in energy transmission, thus realizing the self-regulation of the output voltages. The proposed method enables the voltage deviation and voltage change of the output modules to be suppressed under the unbalanced loads and large load fluctuations. Moreover, the APS can still operate normally when a short-circuit or an open-circuit fault occurs on the output sides. Therefore, the stability and reliability of the APS are improved, and the design difficulty of the post-stage voltage regulator circuit is also reduced. Finally, the simulation results are given, and a prototype containing three output modules was built to verify the effectiveness of the proposed parameter optimization method.

The traction motor (TM) is an essential part of the high-speed train, the health condition of which determines the quality and safety of the vehicle. Hence, this study proposed a novel approach to diagnosing and predicting the TM stator interturn short-circuit fault (SISCF). Based on the Park vector (PV) of the stator current, this method could overcome the interference of current sensor errors, null shift, and motor frequency fluctuations in the actual conditions. More specifically, Park’s transformation was used to obtain the PV of the stator current. Then, the PV was fitted to obtain the elliptical trajectory and its parameters from which the negative sequence component of the stator current could be calculated. Finally, the SISCF diagnosis and prediction method were realized by the magnitude and trend of the negative current as well as the inclination of the trajectory ellipse. Furthermore, the performance of the proposed method was validated by a simulation model and a series of experiments. The simulation results were consistent with the experimental results, supporting the validity and correctness of the method proposed in this study.

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