Comparative Analysis of the Speed Coupling and Torque Coupling Hybrid Modes of a Parallel Hybrid Electric Mini Truck

Two variants of the drivetrain of a post-transmission parallel hybrid electric mini truck namely SCHD and TCHD, operated in the speed coupling (SC) and torque coupling (TC) hybrid modes respectively are analyzed. The equivalent fuel consumption of the conventional and hybrid drivetrains was estimated for three urban drive cycles. Substantial improvement was achieved in the equivalent fuel consumption in comparison with the conventional vehicle for both the variants. TC provided better reduction (up to 55.9%) in the equivalent fuel consumption than SC (up to 34.2%). A metric \(\Delta \)SFC is introduced to determine the mean deviation of the engine operating point relative to its optimum over a drive cycle. \(\Delta \)SFC was evaluated over three drive cycles for the conventional and hybrid drivetrains and was least in case of TCHD, indicating that in TC, the IC engine is operated more efficiently than SC.