A 14-level FCML Inverter for Electric Vehicles with Optimal Capacitors Achieving 175 kW/kg and 380 kW/L Power Density

To enable the development of more electric aircraft, drivetrain inverters must achieve extreme specific power and efficiency while maintaining a low distortion output current. For electric automobiles, the volumetric density is of utmost importance. Flying capacitor multilevel converters (FCMLs), have demonstrated impressive performance in these applications. In this work, an optimal combination of capacitors is utilized for each flying capacitance, which allows for greater than 50% reduction in size compared to the conventional approach. A novel layout of the converter is introduced, which enables the use of these uniquely sized flying capacitors within a minimal box volume. Based on this approach, an 800V, 10.4kW, 14-level FCML prototype is constructed, which achieves 175kW/kg gravimetric power density, 6.2kW/in
³
(380kW/L) volumetric power density and 98.3% peak overall efficiency.