Hybrid Powertrain Growl Mitigation via Torque Break Point Control
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Solution Overview
Problem
Hybrid powertrain systems experience NVH issues such as growl, caused by conditions where engine torque and motor torque fall within specific ranges, leading to perceptible rumble and drivability problems, which existing control methods fail to effectively mitigate.
Innovation Solution
A method to control a hybrid powertrain by monitoring a break point in a non-convex data set defined by engine torque and motor torque thresholds, comparing the target operating point to this break point, and adjusting powertrain operations to avoid ranges conducive to growl, using a controller to manage engine and motor torque contributions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the powertrain operates in the non-convex data set region with specific engine torque and motor torque ranges, then the powertrain can achieve efficient operation and meet torque demands, but growl conditions occur causing NVH issues and drivability problems
Solution Approach 1:
The non-convex data set is segmented into multiple convex sub-regions by identifying break points. The controller divides the operating space into regions where growl conditions can be avoided, allowing the powertrain to efficiently operate in safe regions while transitioning through controlled paths that bypass problematic torque combinations.
Solution Approach 2:
The controller dynamically adjusts motor torque commands based on the current operating point's position relative to the non-convex data set boundaries. By continuously monitoring engine torque and output torque, the system adapts motor torque in real-time to keep the operating point within safe regions, preventing growl conditions while maintaining efficiency.
2Object-affected harmful factors
If the controller limits motor torque to avoid growl conditions in the non-convex data set, then NVH issues are reduced, but the powertrain's ability to meet torque demands and maintain efficiency is constrained
Solution Approach 1:
The controller changes the motor torque parameter dynamically based on the operating region. When the powertrain operates in safe convex regions, motor torque is allowed to reach its demand-specified value for efficient operation. When approaching the non-convex region boundaries, the controller adjusts motor torque to stay within safe limits, thereby preventing growl while maintaining maximum torque delivery capability where possible.
3Adaptability or versatility
If the powertrain transitions through the non-convex data set region, then operational flexibility is maintained, but growl conditions may occur during transitions
Solution Approach 1:
Before transitioning between operating regions, the controller preliminarily calculates the transition path through the non-convex data set to identify potential growl-prone areas. By anticipating the transition requirements, the controller can plan motor torque adjustments in advance, steering the powertrain through safe paths that maintain operational flexibility while avoiding growl conditions during transitions.
Data Source
AI summary
A method to control a hybrid powertrain including an engine, an electric machine, and a transmission through a transition from an initial operating point to a target operating point includes monitoring a break point in a non-convex data set defined by an engine torque below which a growl condition cannot occur and a threshold low motor torque required for the grown condition, comparing the target operating point to the break point, and controlling the powertrain based upon the target operating point and the comparing.