Hybrid Engine Speed Control to Prevent Charging Torque Saturation
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Solution Overview
Problem
Hybrid vehicle engines operating in speed control mode may produce insufficient torque to charge the traction battery, leading to potential engine speed controller saturation and inefficient operation.
Innovation Solution
Adjusting the electric machine torque to a specified charging torque in response to the requested internal combustion engine torque being within a threshold of the minimum instantaneous torque or greater than a maximum charging torque, thereby preventing excessive torque generation and ensuring efficient battery charging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the engine operates in speed control mode to maintain requested engine speed, then engine speed follows the requested speed, but the engine produces insufficient torque to charge the traction battery
Solution Approach 1:
The system dynamically switches between speed control mode and torque control mode based on operating conditions. The engine speed controller is configured to operate in torque control mode when saturation is detected, allowing the engine to produce sufficient torque for battery charging while avoiding the torque deficiency inherent in speed control mode.
Solution Approach 2:
The system changes the control parameter from speed to torque when saturation conditions are detected. By monitoring the engine speed controller output and detecting saturation, the system switches the controlled parameter to torque, enabling the engine to generate adequate charging torque while maintaining appropriate speed through electric machine control.
2Power
If the electric machine excites the engine's speed controller to generate more torque, then torque output increases, but the engine operates at less efficient operating conditions
Solution Approach 1:
The system uses feedback from the engine speed controller output to detect saturation conditions. When saturation is detected, the system switches to torque control mode, using feedback about the saturation state to make intelligent decisions about control mode selection, thereby avoiding inefficient operation while maintaining necessary torque output.
Solution Approach 2:
The system dynamically adjusts the control strategy based on real-time operating conditions. By switching between speed control and torque control modes, the system optimizes engine efficiency while meeting torque requirements, avoiding the energy losses associated with operating in suboptimal regions.
3Speed
If the engine speed controller becomes saturated, then speed control is maintained, but insufficient engine torque is available to charge the traction battery
Solution Approach 1:
The system changes the controlled parameter from speed to torque when saturation is detected. This parameter change allows the engine to operate in a regime where torque is the primary control variable, enabling sufficient torque generation for battery charging while speed is maintained through electric machine support.
Solution Approach 2:
The system dynamically switches control modes based on saturation detection. When the engine speed controller output indicates saturation, the system transitions to torque control mode, dynamically adapting the control strategy to maintain both speed control functionality and adequate charging torque availability.
Data Source
AI summary
Systems and methods for operating a hybrid vehicle having an internal combustion engine are presented. In one example, the internal combustion engine is operated in a speed control mode and torque of an electric machine is adjusted so that a possibility of an engine speed controller saturating may be reduced.