During the last few decades, insulated-gate bipolar transistor (IGBT) power modules have evolved as reliable and useful electronic parts due to the increasing relevance of power inverters in power infrastructure, reliability enhancement, and long-life operation. Excessive temperature stresses caused by excessive power losses frequently cause high-power-density IGBT modules to fail. As a result, module temperature monitoring techniques are critical in designing and selecting IGBT modules for high-power-density applications to guarantee that temperature stresses in the various module components remain within the rated values. In this paper, a module’s different losses were estimated, a heating pipe system for the thermal power cycling technique was proposed, and finite element method (FEM) thermal modeling and module temperature measurement were performed using ANSYS Icepak software version 2022 R1 to determine whether the IGBT module’s temperature rise was within acceptable bounds. To test the proposed technique, a proposed design structure of the practical railway application with a 3.3 MW traction inverter is introduced using commercialized IGBT modules from Semikron company with maximum temperature of about 150 °C. the FEM analysis results showed that the maximum junction temperature is about 109 °C which is in acceptable ranges, confirming the appropriate selection of the employed IGBT module for the target application.

Power system disruptions can be categorized as issues with the quality of electricity brought on by voltage sags, lightning strikes, and other system-related interferences. The static transfer switch (STS) has recently emerged as the most important technology for electric power transmission, distribution, and control systems to manage power supply during power system disruption issues, particularly in cost-effectively supplying power to critical loads and sensitive loads without interruption. In this paper, for the switching between the two AC sources during the voltage disruptions issue with low transfer time, a smart static transfer switch (SSTS) based on a digital switching algorithm and Triac semiconductor switch is proposed and experimentally tested. A digital switching algorithm based on online AC voltage sensing and zero-crossing detection is proposed and implemented inside a DSP MCU. The printed circuit board (PCB) of the proposed SSTS is designed and manufactured for the experimental performance investigation with different AC input voltage conditions. A comparative study based on the advantages and disadvantages of the proposed SSTS system with the previous works is also presented. A smart static transfer switch with a transition time of less than one cycle and a digital protection technique during fault conditions is obtained in this work.

This paper proposes a method to improve the output torque of a six-phase permanent-magnet synchronous machine (PMSM) within the same current peak limit through a fifth-harmonic injection into each phase current of the stator. Compared to the fifth + seventh-harmonic current-injection method used to improve the output torque of the six-phase PMSM, the control system can be stably controlled, and the controller design complexity decreased. This is because the harmonic component was converted into a direct current (DC) component and controlled by a proportional-integral (PI) controller instead of the fifth + seventh-harmonic injection method, which converts the harmonic component into an alternating current (AC) component and controls it with a resonance controller. The appropriate fifth-harmonic ratio for maximum output torque through fifth-harmonic injection was selected through optimization using values analyzed via fast Fourier transform (FFT) for stator phase harmonic current terms caused by inverter nonlinearity and motor design errors. Therefore, it was possible to optimize the fifth-harmonic ratio to be injected without requiring torque modeling using the physical properties of the motor. The experimental results were obtained under the rated current condition with six-phase PMSM in the laboratory, and the average output torque increase under fifth-harmonic injection was about 5% compared to the method without harmonic injection.