Methods and system for controlling engine compression braking in a vehicle with a continuously variable transmission

A method, comprising:

• during a vehicle deceleration event where requested deceleration torque cannot be delivered via negative motor torque:
• operating a continuously variable transmission (CVT) via a controller to adjust engine speed according to a first engine speed-to-vehicle speed profile in response to a request for engine compression braking;
• and
• changing operating the CVT via the controller to adjust engine speed according to a second engine speed-to-vehicle speed profile in response to a change in wheel torque request that increases or decreases a power-based target engine speed above or below respective thresholds.

A system for a hybrid vehicle, comprising:

• a continuously variable transmission (CVT);
• a battery coupled to a motor of the hybrid vehicle;
• a controller with computer readable instructions stored on non-transitory memory that when executed during a deceleration event of the hybrid vehicle, cause the controller to:
• operate the CVT to adjust engine speed to a first level determined based on a current vehicle speed and a first engine compression braking profile of engine speed vs. vehicle speed;
• determine a power-based target engine speed to deliver a compression braking power request based on a difference between a driver demanded deceleration power for the compression braking power request and a battery charge power limit of the battery;
• and
• in response to the determined power-based target engine speed increasing above a first threshold based on engine speeds specified by the first engine compression braking profile and a higher, second engine compression braking profile, shift to the second engine compression braking profile and adjust engine speed to a second level determined based on the current vehicle speed and the second engine compression braking profile.