Hybrid Powertrain Torque Control for Driveline Stability
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Solution Overview
Problem
Existing hybrid powertrain systems face challenges in actively damping the driveline, which affects vehicle stability and performance, particularly in managing torque inputs from multiple torque-generative devices like internal combustion engines and electric machines.
Innovation Solution
A control system that monitors and adjusts motor torque commands for electric machines based on closed-loop speed errors and torque constraints, optimizing torque distribution to achieve active damping, engine pulse cancellation, and closed-loop corrections, thereby enhancing driveline stability and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple torque-generative devices are used to increase power output, then power capability is improved, but driveline stability deteriorates due to torque oscillations and mismatches
Solution Approach 1:
The control system continuously monitors the actual output torque and speed of the hybrid powertrain system, compares it with the desired torque trajectory, and adjusts the torque commands to the engine and electric machines in real-time based on the speed error feedback. This closed-loop control actively damps driveline oscillations and maintains stability despite the complexity of multiple torque sources.
Solution Approach 2:
The control system dynamically adjusts the torque distribution between the engine and electric machines based on real-time operating conditions and speed errors. By making the torque commands adaptive and time-varying rather than fixed, the system can respond to changing driveline conditions and actively suppress oscillations, thereby maintaining stability while delivering high power.
2Stability of the object's composition
If active damping control is implemented to improve driveline stability, then vehicle stability is improved, but control complexity increases
Solution Approach 1:
The control system serves multiple functions simultaneously: it manages power distribution between torque-generative devices, controls transmission operating state and gear shifting, regulates power interchange among energy storage devices, and performs active damping to suppress driveline oscillations. By consolidating these functions into a single integrated control architecture, the system achieves vehicle stability without proportionally increasing control complexity.
Solution Approach 2:
The control system automatically adjusts torque commands based on real-time speed error measurements without requiring external intervention or complex operator input. The system self-regulates by comparing actual speed with desired speed and autonomously modifying torque distribution to damp oscillations, thereby achieving stability through self-correcting mechanisms rather than complex external control.
3Stability of the object's composition
If torque commands are continuously adjusted to reduce oscillations, then driveline stability is improved, but response time may be affected
Solution Approach 1:
The control system operates continuously, constantly monitoring speed errors and adjusting torque commands without interruption or discrete steps. This continuous adjustment ensures that damping action is always active, quickly suppressing oscillations as they arise. The uninterrupted control action minimizes the time required to stabilize the driveline while maintaining smooth torque delivery.
Data Source
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AI summary
A powertrain system includes a transmission (10) operative to transfer power between an engine (14) coupled to an input member (12) and a plurality of torque machines (56,72) and an output member (64). A method for controlling the powertrain system includes monitoring system operation and determining an output torque request, determining a closed loop speed error, determining motor torque offsets to the torque machines (56,72) based upon the closed loop speed error, determining output torque constraints based upon the motor torque offsets and the system operation, determining an output torque command based upon the output torque request and the output torque constraints, determining preferred motor torque commands for the torque machines (56,72) based upon the output torque command, reducing the preferred motor torque commands for the torque machines (56,72) using the motor torque offsets to the torque machines (56,72), and adjusting the reduced preferred motor torque commands for the torque machines (56,72) based upon the closed loop speed error.