Hybrid Electric Traction Research Articles

Optimal Power and Energy Modeling and Range Evaluation of a Solar Assist Plug-in Hybrid Electric Tractor (SAPHT)

Environmental problems associated with burning of fossil fuel and the medium-term and long-term supply of fossil fuel itself, particularly oil, make the move toward a global renewable energy economy both desirable and necessary. Considering these constraints, the SAPHT (Solar Assist Plug-in Hybrid Electric Tractor) was designed, constructed, and evaluated for a farm's light-duty applications. Approximately 18% of the energy consumed daily by the SAPHT is supplied by an onboard photovoltaic (PV) array, and the rest is supplied via an electricity grid. In this research, after optimal power and energy modeling, six standard agricultural implements were attached to the SAPHT in order to determine the operating range of each implement. Field test data illustrated that with a 16.5 kWh valve-regulated lead acid (VRLA) battery pack, it was possible to operate a single-bottom moldboard plow and a two-row planter for 4 h, and a standard mower, sprayer, and fertilizer for 3.2 h, 3.6 h, and 3.4 h per day, respectively. In addition, using this battery pack, it was possible to pull a two-ton weighted trailer for 2 h on asphalt with a velocity of 25 km h -1 , for 2.5 h on a sand road at 18 km h -1 , and for 3 h in a field at 9 km h -1 . More operating hours would be available with the use of batteries with higher energy densities at the same weight.

Hybrid Electric Sport Utility Vehicles

Drive-train hybridization improves the fuel economy and emissions of vehicles. This is the concept of hybrid electric vehicles (HEVs). Application of this concept in sport utility vehicles (SUVs), which consume more fuel as compared to passenger cars, will positively have a great impact. However, dynamic performances such as acceleration and gradeability also are of great importance in SUVs. Therefore, the optimum choice of the system hybridization level includes complex tradeoffs between the engine and electric propulsion motor on the one hand and fuel economy, performance, and cost on the other. In this paper, we classify SUVs as small, medium, and large vehicles. Effects of hybridization on the fuel economy and dynamic performances of each class of SUVs are investigated. Different hybridization levels, from mild to full hybrid electric traction systems, are examined.

Effects of Drivetrain Hybridization on Fuel Economy and Dynamic Performance of Parallel Hybrid Electric Vehicles

Hybrid electric vehicles have proved to be the most practical solution in reaching very high fuel economy as well as very low emissions. However, there is no standard solution for the optimal size or ratio of the internal combustion engine and the electric system. The optimum choice includes complex tradeoffs between the heat engine and electric propulsion system on one hand and cost, fuel economy, and performance on the other. Each component, as well as the overall system, have to be optimized to give optimal performance and durability at a low price. In this paper, we look at the effects of hybridization on fuel economy and dynamic performances of vehicles. Different hybridization levels from mild to full hybrid electric traction systems are examined. We also present the optimum level of hybridization for typical passenger cars. This study shows that low hybridization levels provide an acceptable fuel economy benefit at a low price, while the optimal level of hybridization ranges between 0.3 and 0.5, depending on the total vehicle power.