Researchers at the FREEDM Systems Center partnered with Ricardo, Inc. and the US Department of Energy to develop a battery electric drivetrain for Class 8 heavy duty trucks. This presentation will cover the design process of a 300 kVA, 98.5% efficient traction drive inverter, including power device selection, thermal and drive cycle simulation, and current sensor analysis. High power testing equipment and techniques at the FREEDM lab will also be discussed.