Space vector modulation strategy applied to interphase transformers-based five-level current source inverters for electric propulsion

A propulsion system based on the multilevel current source inverter (MCSI), which enables voltage-boosting and high current handling capabilities, is an interesting solution for electric propulsion. In such a system, the associated capacitance values are small and the voltages at the motor terminals are nearly sinusoidal. Such a MCSI employing interphase transformers to produce different input current levels presents the advantage that the employed magnetic cores are separately optimized and volume reduction is achievable through the choice of proper magnetic core materials. However, a suitable modulation strategy is required to minimize input and output ripples, while providing input dc currents balancing, high quality load voltages, reduced dc and/or low frequency voltage components at the interphase transformers and good losses distribution among the power semiconductors. This work proposes a novel space vector modulation strategy that addresses these challenges.