Hybrid Vehicle Controller Torque Oscillation Reduction
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Solution Overview
Problem
Hybrid electric vehicle powertrains face challenges in coordinating control between internal combustion engines and electric motors, leading to driveline torque oscillations and phase lag issues that can result in incorrect wheel torque commands and potential damage to subsystems.
Innovation Solution
A vehicle system controller uses a narrow band notch filter and a fuzzy weight determination method to balance unfiltered and filtered engine power estimates, ensuring accurate torque distribution between the engine and motor while minimizing phase lag effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a narrow band notch filter is used to reject engine power estimate components in the driveline natural frequency range, then driveline torque oscillations are reduced, but phase lag is introduced that affects accuracy of engine power estimation
Solution Approach 1:
The weighting factor is dynamically adjusted based on operating conditions (vehicle speed, acceleration, engine load) to optimize the balance between filtering oscillations and maintaining estimation accuracy. This dynamic adaptation allows the system to use higher filtering weights when oscillations are problematic and reduce weighting when accuracy is more critical.
Solution Approach 2:
The system changes the weighting parameter between filtered and unfiltered engine power estimates based on detected operating conditions. By monitoring parameters like vehicle speed and acceleration demands, the controller adjusts the weighting factor to optimize performance across different driving scenarios.
2Use of energy by moving object
If coordinated control of multiple power sources is implemented to maximize hybridization benefits, then fuel economy and emissions are improved, but complexity of powertrain control increases
Solution Approach 1:
The system continuously monitors actual engine power output against estimated power and uses this feedback to adjust torque distribution between the engine and motor. The controller compares commanded versus actual vehicle acceleration and power demands, then modifies power source coordination in real-time to optimize fuel economy while maintaining simplicity through rule-based control logic.
Solution Approach 2:
The control system automatically adjusts power distribution between engine and motor based on pre-programmed rules and real-time sensor data, eliminating the need for complex manual intervention or overly sophisticated control algorithms. The system serves itself by making autonomous decisions about optimal power source coordination.
3Stability of the object's composition
If filtered engine power estimates are used to reduce oscillations, then driveline stability is improved, but battery power limit violations may occur due to phase lag
Solution Approach 1:
The weighting factor applied to filtered engine power estimates is dynamically adjusted based on operating conditions. During transient conditions where battery power limits are critical, the system reduces the weighting on filtered estimates to prevent phase lag from causing limit violations. During steady-state cruising, higher weighting can be applied for improved stability.
Solution Approach 2:
The weighting factor acts as an intermediary between the filtered and unfiltered engine power estimates, allowing the system to blend the benefits of both approaches. By adjusting this intermediary parameter, the controller can smooth out oscillations while compensating for phase lag effects to maintain battery power limit compliance.
Data Source
AI summary
A control system and method for controlling a hybrid electric vehicle powertrain with mechanical and electro-mechanical power sources that use an intelligent controller adapted to reduce driveline oscillations while minimizing hybrid vehicle battery limit violations. Damping of driveline torque oscillations is accomplished and violations of battery power limits are avoided by filtering estimated engine power.