DC Link Bus Design for High Frequency, High Temperature Converters

Advancements in IGBT device performance and reliability have been important for widespread electric vehicle (EV) and hybrid electric vehicle (HEV) adoption. However, further improvements in device performance are now limited by silicon's (Si) inherent material characteristics. New improvements are being realized in converter efficiency and power density with wide bandgap materials, such as silicon-carbide (SiC) and gallium nitride (GaN), which permit faster switching frequencies and higher temperature operation. On the horizon are ultra-wide bandgap materials such as aluminum nitride (AlN) and aluminum gallium nitride (AlGaN) which hold the potential to push the envelope further. As device operating temperatures and switching frequencies increase, however, the balance of the power conversion system becomes more important: DC bus design, filter components and thermal management. This paper considers a typical 6-pulse inverter application common in EV and HEV power systems and provides an alternative, cost-effective solution to the design of a low-impedance DC bus. In contrast to systems that use bus bars with film or electrolytic dc link capacitors, the proposed high-frequency (HF) bus design reduces parasitic resistance and inductance, tolerates higher temperature and is potentially scalable to MHz frequencies. A prototype was built and compared in simulation to the DC bus design documented for the 2010 Toyota Prius.