Power Electronics Topology Comparison and Improvement for Low Voltage - High Current DC/AC Applications

In this paper, the power electronics topology and semiconductor selection for low voltage (115 $\text{V}_{\text{RMS}}$ phase voltage) and medium power (90 kW) DC/AC applications are presented. Since these special power electronic applications require a low phase voltage, the phase current is consequently higher. The higher current is shown to limit the maximum achievable efficiency compared to an industry standard 230 V converter, even though lower voltage rated semiconductors can be used for the 115 V converter. To explore a suitable topology for this special DC/AC converter application, a 2-level Si IGBT and a 2-level SiC MOSFET converter are compared to industry standard 3-level Si topologies using market available semiconductors. The comparison is realised using semiconductor loss models, and a comparatively LC filter loss model. The applied IGBT loss model is verified with a double pulse test (DPT) setup and finally, besides highlighting the suitable topology using a figure of merit and suitable semiconductor type, the advantage of utilizing an interleaving configuration is discussed for IGBT-based converters.