System and method using friction clutch on electrified vehicle for enhanced shift feel
An electrified powertrain and method that generates and transfers drive torque to a driveline of an electrified vehicle is provided. The electrified powertrain includes an electric drive module (EDM) and a controller. The EDM includes an electric motor having an output, a transmission that is driven by the output of the electric motor, and a clutch that moves between (i) a closed position; (ii) an open position; and (iii) a plurality of slip positions between the closed and open positions. The controller controls the clutch based on operating conditions. The controller: commands a steady state clutch operation and electric motor torque based on a position of an accelerator pedal; determines whether an output torque of the electric motor is at a limit; and commands a simulated shift that modifies a position of the clutch based on a determination that the electric motor is at the limit.
1 . An electrified powertrain that generates and transfers drive torque to a driveline of an electrified vehicle, the electrified powertrain comprising:
an electric drive module comprising:
an electric motor having an output;
a transmission that is driven by the output of the electric motor; and
a clutch that moves between (i) a closed position that transfers torque from the transmission to the driveline; (ii) an open position that decouples torque from the transmission to the driveline; and (iii) a plurality of slip positions between the closed and open positions that partially transfer torque from the transmission to the driveline;
a controller that controls operation of the clutch based on operating conditions including a position of an accelerator pedal, wherein the controller is configured to:
command a steady state clutch operation and electric motor torque based on a position of the accelerator pedal;
determine whether an output torque of the electric motor is at a limit; and
command a simulated shift that modifies a position of the clutch based on a determination that the electric motor is at the limit.
2 . The electrified powertrain of claim 1 , wherein the controller is further configured to:
command a simulated shift that modifies the electric motor torque based on a determination that the electric motor is not at the limit.
3 . The electrified powertrain of claim 2 , wherein the controller is further configured to:
determine whether the simulated shift is complete; and
command steady state clutch operation based on a determination that the simulated shift is complete.
4 . The electrified powertrain of claim 2 , wherein commanding a simulated shift that modifies a position of the clutch comprises:
commanding the clutch to move to a slip position between the open and closed positions for a predetermined time; and
commanding the clutch to move to the closed position.
5 . The electrified powertrain of claim 4 , commanding the clutch to move to the slip position comprises dropping a clutch torque below a holding torque thereby splitting motor torque between propelling the electrified vehicle and accelerating the electric motor.
6 . The electrified powertrain of claim 5 , wherein the controller is further configured to:
command the clutch torque to a larger value than the holding torque of the clutch while the clutch is slipping resulting in additional propulsion for the vehicle beyond torque from the electric motor.
7 . The electrified powertrain of claim 1 , further comprising:
an internal combustion engine (ICE) that selectively drives the driveline.
8 . A method for controlling an electrified powertrain that generates and transfers drive torque to a driveline of an electrified vehicle, the powertrain including an electric drive module having an electric motor that drives an output, a transmission that is driven by the output of the electric motor, and a clutch that moves between (i) a closed position that transfers torque from the transmission to the driveline; (ii) an open position that decouples torque from the transmission to the driveline; and (iii) a plurality of slip positions between the closed and open positions that partially transfer torque from the transmission to the driveline, the method comprising:
commanding, at a controller, a steady state clutch operation and electric motor torque based on a position of the accelerator pedal;
determining, at the controller, whether an output torque of the electric motor is at a limit; and
commanding, at the controller, a simulated shift that modifies a position of the clutch based on a determination that the electric motor is at the limit.
9 . The method of claim 8 , further comprising:
commanding, at the controller, a simulated shift that modifies the electric motor torque based on a determination that the electric motor is not at the limit.
10 . The method of claim 9 , further comprising:
determining, at the controller, whether the simulated shift is complete; and
commanding, at the controller, steady state clutch operation based on a determination that the simulated shift is complete.
11 . The method of claim 9 wherein commanding a simulated shift that modifies a position of the clutch comprises:
commanding, at the controller, the clutch to move to a slip position between the open and closed positions for a predetermined time; and
commanding, at the controller, the clutch to move to the closed position.
12 . The method of claim 11 , further comprising:
commanding, at the controller, the clutch to move to the slip position comprises dropping a clutch torque below a holding torque thereby splitting motor torque between propelling the electrified vehicle and accelerating the electric motor.
13 . The method of claim 12 , further comprising:
commanding the clutch torque to a larger value than the holding torque of the clutch while the clutch is slipping resulting in additional propulsion for the vehicle beyond torque from the electric motor.