Powertrain Torque Control System Stability Validation
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Solution Overview
Problem
The stability of motor vehicles, particularly those with electric drive motors, is compromised by unintentional torque applications due to the high rate of torque change, which existing powertrain control systems fail to adequately manage.
Innovation Solution
A powertrain control system comprising a torque limit calculator, a first torque control module, and a second torque control module, where the torque limit calculator generates a torque control signal based on vehicle operating parameters, and the second torque control module validates and adjusts torque requests to prevent instability, ensuring higher integrity and safety by overriding potentially destabilizing torque requests.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single torque control module is used to manage torque requests, then the system structure is simple, but the system cannot adequately prevent unintentional torque applications that compromise vehicle stability
Solution Approach 1:
The control system is divided into separate functional modules: a torque request module that generates torque requests, a torque limit calculator that determines safe torque limits based on vehicle operating parameters, and a torque control module that reconciles requests with limits. This segmentation allows independent validation of torque requests against stability criteria, preventing unintentional torque applications while maintaining clear functional separation.
Solution Approach 2:
The torque control module acts as an intermediary between the torque request module and the torque limit calculator. It receives both the torque request signal and the torque limit signal, validates the request against the limit, and generates the final torque control output. This intermediary structure enables independent verification of torque requests without requiring complete system redesign.
2Power
If electric drive motors are used to achieve high torque response, then the power delivery capability is improved, but the rate of torque change becomes too high and affects vehicle stability
Solution Approach 1:
The torque limit calculator continuously determines safe torque limits based on current vehicle operating parameters (wheel speeds, steering angle, lateral acceleration) before torque requests are fully executed. By establishing torque limits in advance based on predicted stable operating conditions, the system can rapidly respond to driver inputs while preventing torque applications that would compromise stability.
Solution Approach 2:
The torque limit is not a fixed value but dynamically adjusts based on real-time vehicle operating parameters. The torque limit calculator continuously updates the torque limit signal according to changing wheel speeds, steering angles, and lateral accelerations, allowing the system to maximize power delivery within dynamically determined stability boundaries.
3Reliability
If torque requests are processed without independent validation, then the response time is fast, but the integrity rating cannot meet higher Automotive Safety Integrity Levels
Solution Approach 1:
The torque control module performs self-validation by independently receiving both the torque request signal and the torque limit signal, then autonomously determining whether the request is valid based on the limit. This self-service validation eliminates the need for separate validation modules or complex multi-layer approval processes, maintaining fast response times while achieving higher integrity ratings through independent verification.
Data Source
Figure 1
Figure 2
AI summary
The present invention relates to a powertrain control system (1) for a vehicle. The powertrain control system (1) includes a torque limit calculator (47) for generating a torque control signal based (57) on one or more vehicle operating parameters. A torque request module (43) is provided for generating a torque request signal (45) and a torque control module (7) controls the torque applied by the powertrain. The torque control module (7) is configured to receive the torque request signal (45) from the torque request module (43) and the torque control signal (57) from the torque limit calculator (47) and to control the torque applied by the powertrain in dependence on the torque request signal (45) and the torque control signal (57). The present invention also relates to a control system; and a method of operating a powertrain control system.