Fuel cell technology is continuously gaining ground in E-mobility applications. Fuel cells require a constant supply of pressurized air, for which high-speed turbo compressors with air bearings are an optimal choice to reduce size, guarantee oil-free operation required for the lifetime of the fuel cell, and increase efficiency.
However, the inverter driving the electric motor of the turbo compressor does not scale down with increasing speed; therefore, other technology advances are required to achieve an overall compressor system with low weight. New power electronic topologies (double-bridge voltage sources inverter), cutting edge power semiconductor technology (gallium nitride), and multiobjective optimization techniques allow reducing the inverter size, increasing inverter efficiency, and improving the output current quality and in return lowering the losses in the electric motor. This enables the electrical, mechanical, and thermal integration of the inverter into the compressor housing of very high-speed and compact turbo compressors, thereby reducing the size and weight of the overall compressor system by a factor of two. Furthermore, a turbo compressor with an integrated inverter reduces complexity and cost for operators with savings in casing, cables, coolant piping, and connectors and reduces EMI noise by shielding the high-frequency motor currents with one housing. Beside its main application for fuel cell air supply, e.g. in drones and UAV’s, the advantages gained by an integrated inverter can also be used in other boosting and air handling applications such as advanced air and exhaust handling in combustion engines and air knives. Further information can be found in the article published in frontiers in Mechanical Engineering.
Figure1: Size comparison of (A) state-of-the-art fuel cell scroll compressor (P32H58N2.25 (Air Squared, 2015)) paired with external inverter (CC-120-1000), (B) high-speed air bearing turbo compressor (CT-17-1000 GB (Celeroton, 2017)) paired with external inverter CC-120-1000, and (C) novel high-speed turbo compressor with integrated inverter described in this paper.