Experimental analysis of energy flow and carbon dioxide emissions in plug-in hybrid electric vehicles under different operation modes

Plug-in hybrid electric vehicles are emerging as a viable alternative to conventional internal combustion engine vehicles, demonstrating significant potential for reducing energy consumption and curbing pollutant emissions within the transportation sector. This study used a chassis dynamometer in a laboratory to investigate the energy flow, energy consumption, and carbon dioxide emission characteristics of plug-in hybrid electric vehicles under both charge-depleting and charge-sustaining modes. The research findings indicate that in charge-depleting mode, the high-voltage battery voltage ranges from 320 to 370 V, with current varying between −116.9 and 147.4 A. During the braking process, energy recovery occurs as the electric motor converts mechanical energy into electrical energy to recharge the high-voltage battery. Furthermore, in charge-sustaining mode, the engine charges the high-voltage battery during operation; however, the charging current from the generator is relatively low, reaching approximately −58 A. An analysis of energy consumption revealed that the energy consumption of plug-in hybrid electric vehicles in charge-depleting mode is over 68.3 % lower than that in charge-sustaining mode. Conversely, when electricity consumption is converted to standard coal consumption, the carbon dioxide emission factor in charge-depleting mode (145.40 g/km) is more than 9.5 % higher than in charge-sustaining mode. Therefore, plug-in hybrid electric vehicles exhibit clear advantages in improving energy efficiency and reducing dependence on oil, representing a significant approach to promoting decarbonization in the transportation sector.