Abstract
Multi-speed transmissions with 2–3 speed are considered to be an effective and compact equipment for pure electric vehicles’ (PEV) dynamic and economical improvement. However, the characteristics of fewer gears and larger speed ratio gap not only request uninterrupted shifting quality but also smooth pedalpower pattern to derive demand power of motor from drivers’ input. Due to these features of multi-speed transmissions for PEV, using one fixed pedal-power pattern in conventional ways will cause output torque shock after shifting or force drivers to passively adjust the pedal for constant acceleration. A speed-based unified pedal-power pattern (SUPP) is proposed to interpret the demand power of motor according to the vehicle speed instead of motor speed. The SUPP contains three components including a base, a feedforward and a feedback part to satisfied the different dynamic request under different gears and different speed. Furthermore, the SUPP is integrated with the innovative clutch-to-clutch shifting algorithm which achieves uninterrupted shifting on PEV, and realizes in optimal trajectory of motor operating points during and after shifting. A case study of SUPP is conducted with a two-speed transmission for PEV through both simulation and experiments. The simulation and experimental results prove that the SUPP is able to obtain uninterrupted wheel torque during and after shifting with constant drivers’ intention, and prevent drivers from unnecessary adaptation.
Energy reduction by power loss minimisation through wheel torque allocation in electric vehicles: a simulation-based approach
