In recent years, the powertrains of agricultural tractors have been transitioning
toward hybrid electric configurations, paving the way for a greener future
agricultural machinery. However, stability challenges arise in hybrid electric
tractors due to the relative small capacity to perform power-intensive tasks,
such as plowing and harvesting. These operations demand significant power, which
are supplied by the electric power take-off system. The substantial disturbances
introduced by the electric power take-off system during these tasks render
conventional small-signal analysis methods inadequate for ensuring system
stability. In this article, we first develop a large-signal model of the onboard
power electronic systems, which includes components such as the diesel
engine–generator set, batteries, in-wheel motors, and electric power take-off
system. By employing mixed potential theory, we conduct a thorough analysis of
this model and derive a stability criterion for the onboard power electronic
systems under large disturbance conditions. Using this criterion, we estimate
the stability boundaries of the onboard power electronic systems and evaluate
the influence of various circuit parameters on its performance under large load
fluctuations. Finally, case studies are presented to validate the proposed
stability criterion and to demonstrate the impact of key circuit parameters on
system stability.
