ENGINE START/STOP CONTROL FOR A HYBRID ELECTRIC POWERTRAIN

A controller executes a method to manage an engine connect/disconnect decision in a powertrain having an engine, transmission, electric machine, and a battery pack and power inverter module (“TPIM”). In response to vehicle ground speed being less than a calibrated maximum electric vehicle accelerator pedal signal (“EV”) level, the controller calculates a delta APS (“ΔPS”) value by subtracting a scaled APS value from the actual APS level. The scaled APS value is a scaled variant of a maximum EVvalue selected from a maximum EVStable, the latter populated based on inverter temperature, state of charge of the battery pack, and ground speed. When the ΔAPS value exceeds a threshold, the controller connects the engine to the transmission via an engine disconnect clutch. The engine is disconnected based on acceleration of the vehicle and the above-noted factors.