Experimental Evaluation of EMI and Efficiency in a Hybrid T-Type Wide-Bandgap Converter

This paper presents an experimental study of a three-level hybrid T-type converter using wide-bandgap (WBG) semiconductors, specifically gallium nitride (GaN) and silicon carbide (SiC). The proposed topology takes advantage of the high-voltage capability of SiC MOSFETs and the low switching losses of GaN e-HEMTs, offering significant advantages in efficiency and power density. Futhermore, an adaptive level-shift algorithm is introduced, enabling transitions between two-level and three-level operation modes to enhance fault tolerance and maximise current capability. The behaviour of the power converter and the adaptative algorithm is analysed through experiments performed using a real hybrid T-type converter. Experimental results validate the reliability of the proposed level-shift algorithm. Additionally, the experiments demonstrate that high switching frequencies not only have minimal negative effects on power losses and EMI but also improve THD, confirming the hybrid T-type converter as a robust solution for high-efficiency applications.