Motor Torque Control for Electric Vehicle Slip Prevention
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Solution Overview
Problem
Existing motor torque control systems for electric vehicles fail to stabilize the vehicle body during sudden clutch connection or gear shift-down operations, leading to potential slipping and instability, especially during cornering, as they initiate control only after slip detection at the rear wheel.
Innovation Solution
A motor torque control device and method that includes a storage unit for theoretical driving wheel rotating speeds, gear stage detection, engine speed detection, and torque control means to increase output torque when the relative difference between detected and theoretical driving wheel rotating speeds exceeds a threshold, initiating control before slip generation to prevent instability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If control is initiated only after slip detection at the rear wheel, then the control system remains simple and responsive to actual slip conditions, but the vehicle body becomes unstable and driver anxiety increases during sudden clutch connection or gear shift-down operations
Solution Approach 1:
The control system initiates torque control before slip actually occurs by detecting parameters that precede slip conditions. Specifically, when the driving wheel rotating speed exceeds the theoretical value by a predetermined threshold (indicating impending slip), the control device proactively adjusts motor torque to prevent slip, rather than waiting for slip detection. This preliminary action stabilizes the vehicle body during sudden clutch connection or gear shift-down operations.
Solution Approach 2:
The control system continuously monitors the relationship between driving wheel rotating speed and theoretical driving wheel rotating speed (calculated from engine/motor speed and transmission ratio). This feedback mechanism detects deviations that indicate impending slip conditions, enabling the control system to respond appropriately by adjusting motor torque to maintain stability and prevent slip occurrence.
2Speed
If control is initiated at the moment of slip generation, then the response time is minimized, but the vehicle body is already in an unstable state and safety is compromised during cornering travel
Solution Approach 1:
The control system performs preliminary torque adjustment when the driving wheel rotating speed exceeds the theoretical value by a predetermined threshold, preventing slip from occurring in the first place. This is especially critical during cornering travel where slip could lead to vehicle overturn. By acting before slip conditions fully develop, the system maintains vehicle stability and safety.
Solution Approach 2:
The control system applies counter-torque to the motor in advance when detecting parameters that indicate impending slip (driving wheel speed exceeding theoretical speed by threshold). This preliminary anti-action counteracts the forces that would cause slip and subsequent vehicle instability, particularly during cornering maneuvers where the consequences of slip are most severe.
3Device complexity
If the control system waits for slip detection before initiating torque control, then the control logic remains simple, but the vehicle body stability deteriorates during sudden clutch connection or gear shift-down operations
Solution Approach 1:
The control system initiates torque control when the driving wheel rotating speed exceeds the theoretical value by a predetermined threshold, which occurs before actual slip. This preliminary detection and response mechanism maintains vehicle body stability during sudden clutch connection or gear shift-down operations without requiring complex control logic, as it relies on a clear threshold-based detection criterion.
Data Source
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AI summary
The invention relates to a motor torque control device (and a related method) for an electric vehicle including a storage unit that stores a theoretical driving wheel rotating speed based on a correspondence relationship with a predetermined engine speed in each gear stage of a transmission of a vehicle; gear stage detection means for detecting the gear stage when currently travelling; engine speed detection means for detecting an engine speed; driving wheel rotating speed detection means for detecting a driving wheel rotating speed; and torque control means for controlling output torque, in which the output torque is increased so that a current driving wheel rotating speed becomes close to the theoretical driving wheel rotating speed when a relative value of a calculated value which is calculated by using the detected driving wheel rotating speed with respect to a calculated value which is calculated by using the theoretical driving wheel rotating speed is equal to or greater than a first threshold value.