Adopting MOSFET multilevel inverters to improve the partial load efficiency of electric vehicles

The efficiency of the electric powertrain has a direct influence on the cost and range of electric vehicles, which are the two key factors hindering the public acceptance of electric vehicles (EVs). Inverters, as an important component of the electric powertrain, have a high efficiency at full load, but an unsatisfying performance at partial load due to the bipolar characteristics of IGBT. To improve the partial load efficiency, this paper proposes to use multilevel inverters composed of low voltage MOSFETs to replace six-pack IGBT inverters in EVs. The proposal is justified by a detailed analysis based on a BMW i3 vehicle model and an accurate model of semiconductor losses in ANSYS Simplorer. Moreover, a cost comparison proved that the multilevel inverter using common low voltage MOSFETs is the best option among all the solutions considering the current costs of the components.