Due to the potential on decreasing fuel consumption and design flexibility,
parallel configurations are widely used for hybrid electric vehicles (HEVs).
However, the fuel economy and economic profitability of parallel HEVs for
heavy-duty truck applications under Chinese driving conditions still need to be
investigated. It is uneasy to improve the fuel economy of parallel HEVs with a
single electric motor from control perspective only. In this article, the
battery size of the architecture is optimized by using the dynamic programming
(DP) approach, based on a dynamic degradation model of the LiFePO4
battery. Moreover, based on the DP results, a near-optimal control strategy of
the hybrid powertrain system for online application is proposed. Finally, with
two economic assumptions, the initial costs, operation costs, and payback
periods are obtained in a total cost of ownership framework perspective. The
simulation results show that the fuel consumption can satisfy the Stage 3 fuel
consumption standard, which will be implemented in 2021. In addition, more than
18% fuel economy is achieved when compared to that of the conventional
heavy-duty truck. Under present economic scenarios, the payback period of
parallel hybrid electric heavy-duty truck is less than five years. When
assumptions are benefited to electrification, the payback period will even be
less than three years.