Life Cycle Costs of Series Hybrid Tractors

Abstract

Aiming to investigate the impact of battery capacity configuration on system efficiency and life cycle cost (LCC) for high-horsepower hybrid tractors, thereby addressing the research gap in battery capacity optimization design for hybrid tractors, taking a 190kW series hybrid tractor as the research object, an LCC evaluation system encompassing equipment procurement, battery replacement, and fuel consumption was established. A two-level battery capacity optimization method combining enumeration and dynamic programming (DP) was proposed: the outer layer investigated the influence of battery capacity on LCC under time-varying weights of energy and battery prices through global search via enumeration method, while the inner layer employed DP algorithm for optimal control of energy management strategies in hybrid tractors. A tractor simulation platform was developed by using Matlab/Simulink to quantitatively analyze the coupling mechanism between battery capacity and energy management strategies on system efficiency throughout the tractor’s lifecycle. Simulation results indicated that within the 2.2~110A·h battery capacity range, increasing battery capacity benefited fuel consumption reduction and battery lifespan extension;the 24.2A·h configuration represented the fuel consumption inflection point, beyond which capacity increase yielded minimal efficiency improvement;when battery capacity reached 52.8A·h, no replacement was required based on cycle life, but the nonlinear battery capacity-LCC relationship showed 22A·h configuration minimized LCC to 3.9093 million yuan. The proposed “technical parameters-life cycle cost” optimization framework established theoretical paradigms and provided valuable references for hybrid system design in agricultural machinery.

Keywords: hybrid tractors;life cycle cost;battery capacity configuration;dynamic programming;energy management strategy