BiSG Belt Torque Limiting for Heat and Wear Control
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Solution Overview
Problem
Existing systems for controlling electric machines in vehicles with belt-integrated starter generators (BiSG) fail to dynamically manage torque communication through belts, leading to excessive heating and reduced belt lifespan due to fixed torque limits.
Innovation Solution
A control system that dynamically adjusts torque limits based on torque communication signals, using controllers to determine and manage torque thresholds and monitor values, ensuring optimal belt temperature and reducing wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed torque limit is used for the electric machine, then the control system is simple to implement, but the belt experiences excessive heating and reduced lifespan
Solution Approach 1:
The patent implements dynamic torque limiting by continuously monitoring belt temperature and adjusting the torque limit in real-time based on actual thermal conditions. This replaces fixed torque limits with adaptive control that responds to changing operating conditions, thereby extending belt lifespan while maintaining manageable control complexity through sensor feedback and iterative adjustment.
Solution Approach 2:
The control system incorporates temperature sensing feedback from the belt to dynamically adjust torque limits. The belt temperature sensor provides continuous information about thermal state, enabling the controller to modify torque commands accordingly. This feedback loop prevents excessive heating by reducing torque when temperature thresholds are approached, thereby extending belt life without requiring overly complex control architecture.
2Power
If torque communication through the belt is increased to improve power transmission, then the power transmission efficiency improves, but the belt temperature increases excessively
Solution Approach 1:
The patent dynamically changes the torque limit parameter based on measured belt temperature. When temperature remains within acceptable ranges, higher torque limits are permitted to maximize power transmission. When temperature approaches critical thresholds, the torque limit is reduced to prevent excessive heating. This parameter adaptation enables the system to optimize power transmission while maintaining safe operating temperatures.
Solution Approach 2:
The control system periodically monitors belt temperature and adjusts torque limits in response to thermal conditions. This periodic measurement and adjustment cycle allows the system to maintain high power transmission during cool periods while preventing overheating during extended high-load operation, effectively managing the trade-off between power transmission and temperature control.
3Duration of action of stationary object
If the belt is designed to handle higher torque to reduce replacement frequency, then the belt longevity improves, but the risk of excessive heating and failure increases
Solution Approach 1:
The control system takes preliminary action by monitoring belt temperature continuously and proactively adjusting torque limits before excessive heating occurs. By detecting temperature trends early and reducing torque commands in advance, the system prevents the belt from entering dangerous thermal states, thereby extending safe operation duration without increasing the risk of thermal failure.
Solution Approach 2:
The patent implements a form of cushioning by maintaining torque limits below maximum capacity thresholds during normal operation. This conservative approach creates a safety margin that prevents the belt from experiencing extreme thermal stress, thereby extending service life without compromising reliability. The system cushions against potential overheating by never allowing the belt to operate at maximum torque capacity for extended periods.
Data Source
AI summary
Embodiments of the present invention provide a control system (200) for an electric machine (120) of a vehicle, the control system comprising one or more controllers, the control system comprising input means (230) to receive a torque communication signal (255) indicative of torque communication through a belt (130) associated with the electric machine, processing means (210) arranged to determine a torque limit for the electric machine in dependence on the torque communication signal and a first torque threshold, and output means (240) arranged to output a torque limit signal (245) in dependence on the torque limit to control the torque communicated through the belt associated with the electric machine.