Improving the Overall Efficiency of Automotive Inverters Using a Multilevel Converter Composed of Low Voltage Si mosfets

In order to improve the driving range and reduce the cost of battery electric vehicles through a higher efficiency, this paper proposes to adopt multilevel converters using low-voltage Si mosfets in the electric powertrains. A multilevel Si mosfet inverter, a conventional insulated-gate bipolar transistor (IGBT) inverter, and a SiC mosfet inverter are modeled and compared using a reference vehicle over various driving cycles. The costs of the three solutions are also compared. It is shown that the multilevel Si mosfet inverter has a rather high efficiency and realizes the lowest cost among the three solutions even when the worst case of cost is considered. Sensitivity analysis also shows that the multilevel Si mosfet inverter is suitable for a wide range of vehicle concepts in addition to the reference vehicle. Moreover, the multilevel topology also features lower electromagnetic interference and provides modularity. Therefore, Si mosfet-based multilevel inverters are proved in this paper to be an appropriate option to improve the efficiency and reduce the cost of electric powertrains.