Overview of Electric Turbocharger and Supercharger for Downsized Internal Combustion Engines

Forced induction uses otherwise wasted exhaust gases to improve the volumetric efficiency of an engine allowing for higher thermodynamic efficiency. As the fuel economy and greenhouse gas emission standards are projected to be much more stringent globally, the use of a forced induction engine in passenger cars and light duty trucks has become a new trend in automotive industry. The aerodynamic matching of an exhaust driven turbocharger is a compromise of transient response at low exhaust energy levels and power targets on high. The trend toward highly boosted downsized engines results in larger aerodynamic matches compromising responsiveness on the low side, known as turbo lag. The electrification of FIS [electric FIS (EFIS)] has emerged as a feasible solution, and it also possesses numerous benefits depending on its topologies. This paper provides a comprehensive study on the EFIS by investigating system level topologies, performance, various types of highspeed machines, power electronics, and control techniques. The advantages and disadvantages of existing EFIS are summarized, and the new challenges and opportunities are also introduced.