Vehicle Drive Torque Gating for Wheel Slip Prevention
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Solution Overview
Problem
Existing drive devices for electric vehicles with high-performance systems face issues of vehicle destabilization due to excessive drive torque generation exceeding static friction limits, necessitating a structurally simple and fault-tolerant signal processing path between the accelerator pedal and drive unit to ensure vehicle safety.
Innovation Solution
A drive device with an actuator control unit featuring an enabling device that checks torque requests downstream, ensuring safety integrity levels meet ISO 26262 ASIL D for the accelerator pedal and actuator control unit, while allowing simpler and cost-effective drive control systems by limiting or blocking potentially destabilizing torques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the drive controller generates high torque to meet performance requirements, then the vehicle's drive capability is improved, but the risk of vehicle destabilization increases when torque exceeds the static friction limit
Solution Approach 1:
The actuator control unit performs preliminary verification of the torque request against the destabilization threshold before the torque is actually applied to the drive wheels. This advance check prevents excessive torque from reaching the wheels that would cause wheel slip and vehicle destabilization, while allowing the drive controller to maintain its high-performance torque generation capability.
Solution Approach 2:
The actuator control unit serves as an intermediary between the drive controller and the electric motor. It receives the torque request from the drive controller, verifies it against the stored destabilization threshold, and only allows the torque to pass through to the motor if it is within safe limits. This intermediary position enables the system to maintain both high performance and safety.
2Reliability
If the drive control system performs comprehensive torque verification, then vehicle safety is improved, but the device complexity and computational requirements increase
Solution Approach 1:
The torque verification function is extracted from the drive control system and placed in the actuator control unit. This separation allows the drive control system to focus on torque generation while the actuator control unit handles safety verification. The extraction reduces the complexity burden on the drive control system while maintaining comprehensive safety checks.
Solution Approach 2:
The actuator control unit performs self-verification of torque requests by comparing them against its own stored destabilization threshold. This self-service approach eliminates the need for complex inter-controller communication and verification protocols, simplifying the overall signal processing path while maintaining high functional safety standards.
3Reliability
If the actuator control unit verifies torque requests against destabilization threshold, then fault tolerance is improved, but the processing time and response delay increase
Solution Approach 1:
The actuator control unit pre-stores the destabilization threshold value in its memory before any torque verification is needed. This preliminary preparation eliminates the need for real-time threshold calculation or complex lookup operations during torque verification, significantly reducing processing time while maintaining comprehensive safety checks.
Solution Approach 2:
The verification process compares torque requests against a pre-defined threshold parameter rather than performing complex real-time analysis. This parameter-based approach transforms a potentially time-consuming verification process into a simple, fast comparison operation that maintains high fault tolerance with minimal time penalty.
Data Source
AI summary
The invention relates to a drive device for a vehicle, comprising an accelerator pedal (FP) in signal communication with a drive controller (ASG) which requests a torque (MASG) on the basis of an accelerator-pedal raw value (RFP), by means of which torque an actuator control apparatus (PWR) of an actuator (EM), in particular a pulse converter of an electric machine, can be controlled in driving mode. According to the invention, the actuator control apparatus (PWR) comprises a disconnection device (3), by means of which error determination of the torque (MASG) requested by the drive controller (ASG) can be carried out.