Off-Road Vehicle Hybridization Methodology Applied to a Tractor Backhoe Loader

Hybrid electric systems have gained relevance in off-road applications because it allows the internal combustion engine to operate near its maximum efficiency region, ensuring reduction of gas emissions and fuel consumption. This paper presents a comprehensive approach for electrification projects applied to this sort of equipment, including the technical feasibility study for an existing tractor backhoe loader in a real work cycle. For the hybrid proposal, besides the gain of having the internal combustion engine near its maximum efficiency point with the addition of an energy storage device, the electrification approach includes the improvement of the hydraulic system operation by adding a variable speed drive, which reduces the losses due continuous oil flow recirculation presented on the conventional model. The methodology involves modeling of the conventional system and the design and modeling of the proposed hybrid system. Both models are submitted to experimental data gathered from real work cycle for analysis and comparison. A supercapacitor is considered as the energy storage device for this application due the low amount of energy required and high frequency of charge and discharge cycles. The fuel safe achieved with the electrification is up to 40% for the specific vehicle and duty cycle studied.