Electrification of turbocharger and supercharger for downsized internal combustion engines and hybrid electric vehicles-benefits and challenges

Forced induction technology (turbocharging and supercharging) can enhance the performance of an internal combustion engine by compressing inlet air charge, allowing full engine power to be produced efficiently. 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 inevitable trend in the automotive industry. However, the conventional forced induction system suffers from the slow transient response, especially when the engine speed is low, a phenomenon typically known as turbo lag. The electrification of forced induction system, called electric forced induction system (EFIS), has emerged as a feasible solution and it also possesses numerous benefits depending on its topologies. This paper provides a comprehensive study on EFIS by investigating system level topologies, performance, various types of high-speed machines, power electronics, and control techniques. The advantages and disadvantages of existing electric forced induction system are summarized and the new challenges and opportunities are also introduced.