Electric Traction Torque Monitoring With Direction-Specific Thresholds
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Solution Overview
Problem
Existing torque monitoring systems in electric traction machines of electrified vehicles are inefficient, leading to unnecessary alerts and reconfigurations, and there is a need to optimize torque accuracy and reduce costs while ensuring operational safety.
Innovation Solution
A method involving two distinct torque monitoring thresholds for forward and reverse directions, with different threshold values and durations, to differentiate between normal and anomalous operations, triggering appropriate reconfigurations based on these thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a torque sensor is integrated into the drive shaft to directly measure driving torque, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent introduces intermediate measurement variables (vibration acceleration, housing movements) that can be obtained through simpler sensors. These intermediate measurements serve as mediators to infer the driving torque without requiring direct torque sensing, thus reducing device complexity while maintaining measurement capability
Solution Approach 2:
The patent replaces direct mechanical torque measurement with an indirect measurement system using vibration sensors and signal processing. Instead of using a mechanical torque sensor in the drive shaft, the system uses vibration acceleration measurements combined with mathematical models to calculate torque, substituting mechanical measurement with a sensor-based indirect measurement approach
2Device complexity
If vibration sensors are used to indirectly measure driving torque, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent employs feedback mechanisms where the measured vibration signals are continuously processed and used to update torque estimates. The system uses the relationship between vibration characteristics and torque to provide feedback that refines the measurement accuracy, allowing precise torque determination from indirect vibration measurements
Solution Approach 2:
The patent changes the measurement parameters from direct torque to vibration acceleration and housing movements. By measuring different physical parameters (vibration characteristics at various frequencies and positions) and using mathematical relationships to derive torque, the system achieves accurate torque measurement while using simpler, less intrusive sensors
3Device complexity
If existing torque estimation methods using vibration signals are applied, then device complexity is reduced, but reliability deteriorates due to signal contamination
Solution Approach 1:
The patent segments the vibration signal analysis into different frequency components and spatial positions. By analyzing vibrations at multiple locations on the housing and separating frequency components, the system can isolate torque-related signals from contamination sources, improving reliability while maintaining simple device architecture
Solution Approach 2:
The patent applies local quality by placing sensors at specific locations on the housing where torque-induced vibrations are most prominent and least contaminated by other sources. The measurement strategy focuses on local vibration characteristics at optimized positions to maximize signal quality and measurement reliability
Data Source
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AI summary
The present invention relates to a method for monitoring the driving torque of an electric traction machine of an electrified vehicle, involving determining (22) a torque difference (EC) between a setpoint torque (CC) and an achieved torque (CR), and determining (23) whether the rotor is rotating in the forward driving direction or the reverse driving direction. According to the invention, the method involves comparing (24) the torque difference (EC) against a first threshold (S1) in the forward driving direction, and comparing (27) the torque difference (EC) against a second threshold (S2) in the reverse driving direction, and activating a reconfiguring (25, 28) of the electric machine on the basis of the result of the comparison (24, 27), the second threshold (S2) having a higher value than the first threshold (S1). The invention applies to electrified vehicles with fully electric drive and with hybrid drive.