Vehicle Driveline Torque Balancing for Uniform Motor Aging
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Solution Overview
Problem
The uneven thermal aging of electrical machines and power electronics in vehicle powertrains due to non-symmetrical operation leads to reduced service life and availability.
Innovation Solution
Implement a modified operation strategy where the more heavily loaded electrical machine in non-symmetrical operation is operated with a limited torque and/or torque gradient, or switched off, to compensate for differential aging, ensuring a more uniform aging process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If non-symmetrical operation of electrical machines is used to perform powershifting in the transmission, then electrodynamic powershifts can be executed, but the electrical machines and power electronics age differently leading to reduced service life
Solution Approach 1:
The control device changes the operating parameters (torque and torque gradient) of the electrical machines based on their individual aging states. After a non-symmetrical operation, the machine that was more heavily loaded is subsequently operated with limited torque and torque gradient, while the other machine operates with higher values, thereby equalizing the cumulative thermal load and aging between the two machines and their associated power electronics
Solution Approach 2:
The system alternates between symmetrical and non-symmetrical operation modes in a periodic manner. Non-symmetrical operation is used when powershifting is required, followed by a compensatory phase where the loading is redistributed to balance aging. This periodic switching between operation modes ensures both productivity and reliability are maintained over time
2Power
If one electrical machine is loaded with higher torque and torque gradient in non-symmetrical operation, then powershifting can be performed, but that machine and its power electronics experience accelerated aging
Solution Approach 1:
The control device continuously monitors the operating state and aging indicators of both electrical machines and their associated power electronics. Based on this feedback, it dynamically adjusts the torque and torque gradient allocation between the machines, ensuring that the machine which has accumulated more thermal load receives reduced loading in subsequent operations, thereby equalizing their respective operating times and service lives
Data Source
AI summary
A vehicle powertrain has a first electrical machine with first power electronics and a second electrical machine with second power electronics. In symmetrical operation, the first and second electrical machines are loaded or operated with the same torque and with the same torque gradient. In a non-symmetrical operation, the first and second electrical machines are loaded or operated with a different torque and/or with a different torque gradient. If, after non-symmetrical operation the symmetrical operation is resumed, a subsequent modified operation can be used in which the electrical machine that was loaded or operated in non-symmetrical operation with higher torque and/or a higher torque gradient, is loaded or operated with a limited torque and/or with a limited torque gradient or is switched off or decoupled for a defined period of time, thereby at least partially compensating for a different aging of the electrical machines due to non-symmetrical operation.