An Electric-Drive to Parallel-Drive Mode Transition Control Strategy for a P2 Hybrid Powertrain

Hybrid powertrains have become many original equipment manufacturers (OEMs)’ choice to meet ever-stringent fuel consumption regulations. A P2 powertrain technology is widely adopted by automotive OEMs to reuse existing engines and transmission production capacity and reduce investment. A standalone P2 module of an integrated e-motor with an engine decoupling wet clutch is developed and applied in a transverse-mounted P2 hybrid powertrain system. A P2 hybrid powertrain controller has been developed to test and validate the P2 module and control strategy. This P2 powertrain system with a decoupling clutch capable of slipping control enables the vehicle launch or low-speed drive in engine direct-drive mode. A control algorithm that controls the clutch slipping to transmit the desired cranking torque from P2 e-motor to fast-start the engine during the drive mode change from Electric drive to Parallel drive has been developed and validated. The proposed engine slip-start with clutch pressure control has achieved robust results of a fast and smooth transition from the electric to hybrid mode.