Fuel Economy Improvement Analysis of Parallel and Power-Split Hybrid Electric Vehicles

The demand for the development of low-emission vehicles is increasing aided by a global trend toward gradual enforcement of regulations on fuel economy and emissions of vehicles. The market share of HEVs is expected to grow from 5 % in 2015 to 17.5 % in 2050. The purpose of this study is to quantitatively evaluate the strengths and weaknesses of parallel HEV and power-spilt HEV for each powertrain system element. Power-split HEV has a drawback of power circulation, and for this reason, more energy has been generated by engine. Engine operational time and the engine loss of the power-split HEV are greater than that of parallel HEV. The advantage of power-split HEV is that it has a simple structured drivetrain compared to parallel HEV. Therefore, the drivetrain loss is less. Accordingly, the fuel consumption of the parallel HEV and power-split HEV is about the same in the UDDS 2 cycle, 17.1 % less in parallel HEV in HWFET. In HWFET, the disadvantage of the power-split HEV is more influential, and it appears that the fuel economy is worse than that of the parallel HEV.

Automated summary

The demand for low-emission vehicles is increasing due to the global trend towards stricter regulations on fuel economy and emissions. This study aims to evaluate the strengths and weaknesses of parallel hybrid electric vehicles (HEVs) and power-split HEVs. Power-split HEVs have the disadvantage of power circulation, resulting in more energy generated by the engine. However, they have a simpler drivetrain structure and lower drivetrain losses compared to parallel HEVs. The fuel consumption of the two types of vehicles is similar in the UDDS 2 cycle, but the parallel HEV performs 17.1% better in HWFET.