Analysis of Phase Voltage Oscillation Affected by Switching State Changes of Other Phases in Three-Phase T-Type Converter

Three phase high-voltage and high-frequency converters may encounter some challenges including voltage oscillation across the switch's drain-source because of the stray inductance of the circuit and also voltage oscillation of each phase due to the switching state changes of other phases. The former is investigated a lot in literature. However, for better understanding of the latter issue, this work introduces analytical methodology for modeling the voltage oscillation at each phase as the result of the switching state changes in other phases. The proposed model is utilized for several operating point of the modulation reference waveform to cover all possible working scenarios of the converter operation. The voltage oscillation of random phase with respect to the middle point of DC link, which is grounded in T-Type converter, is investigated at the time of switching state changes in other phases. This has been carried out by simulating the equivalent circuit model in LTspice, which is considering anticipated parasitic capacitances in the real power module used in experiment. Finally, using this developed model, the resulted data was in good agreement with the experimental results, which validate the proposed model.