Hybrid Vehicle Torque Synchronization During Upshift
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Solution Overview
Problem
In hybrid electric vehicles, the simultaneous reduction of engine and motor torque during an upshift is challenging due to response lag differences and communication delays in the control area network, which can degrade drivability and shift quality.
Innovation Solution
A control scheme and algorithm that coordinates the reduction of motor torque followed by a delayed reduction of engine torque, accounting for delays in the control area network to synchronize the torque reductions and improve shift quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If motor torque and engine torque are reduced simultaneously during an upshift, then drivability and shift quality are improved, but response lag differences and communication delays cause the torque reductions to become unsynchronized
Solution Approach 1:
The controller applies preliminary action by commanding the motor torque reduction before the engine torque reduction, with a predetermined time delay. This anticipates the response lag differences between the motor and engine systems, ensuring that both torque reductions are synchronized in practice despite the inherent time delays in the system.
2Ease of operation
If the controller commands torque reductions through the control area network, then coordination between motor and engine is achieved, but communication delays in the CAN cause asynchrony in torque reductions
Solution Approach 1:
The controller compensates for communication delays by issuing the engine torque reduction command with a predetermined time delay after the motor torque reduction command. This preliminary timing adjustment ensures that both torque reductions are synchronized despite the inherent CAN communication delays.
Solution Approach 2:
The controller monitors the actual torque reductions from both the motor and engine, and adjusts the timing of torque reduction commands based on the observed response. This feedback mechanism ensures that the torque reductions remain synchronized even as system conditions change.
3Reliability
If the controller accounts for response lag differences between motor and engine, then simultaneous torque reductions are achieved, but the control algorithm complexity increases
Solution Approach 1:
The controller changes the timing parameter of the torque reduction commands by applying a predetermined time delay to the engine torque reduction command. This simple parameter adjustment compensates for the response lag differences between the motor and engine systems without requiring a complex control algorithm.
Data Source
AI summary
A control system is provided to account for differences in engine response times and motor response times during an upshift in a transmission. A vehicle includes a driveline that has an engine, a traction motor, and a transmission selectively connected in series. A control area network (CAN) connects a plurality of controllers. At least one of the controllers is programmed to, during an upshift in the transmission, output signals over the CAN to reduce torque of the traction motor. The controller also reduces the engine torque based on signal delays in the CAN.