CONTROLS AND METHODS FOR OPERATING ELECTRIC POWERTRAIN

A vehicle includes and engine and a transmission having a torque converter with an impeller and a turbine. An electric machine is fixed to the impeller. At least one controller is programmed to, in response to a difference between measured and estimated speeds of the impeller exceeding a threshold, command a torque to the electric machine based on a maximum of the measured and estimated speeds of the impeller, and programmed to, in response to the difference being less than the threshold, command another torque to the electric machine based on the measured speed of the impeller.