Electric Vehicle Slip Control via Torque Feedback
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Solution Overview
Problem
Existing electrically driven vehicles face challenges in suppressing drive wheel slipping, particularly on slick surfaces, due to difficulties in detecting wheel speeds in low-speed regions, leading to unstable vehicle behavior and inefficient torque control.
Innovation Solution
An electrically driven vehicle with a slip control system that regulates motor torque based on predefined setting values, using a slip state discriminator, torque command arithmetic unit, and torque controller to detect and correct slipping even in low-speed regions where wheel speeds are undetectable, ensuring drive wheels do not exceed specific speed thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional speed sensors (electromagnetic pickup or Hall IC) are used to detect wheel speeds, then speed detection is possible in most regions, but detection fails or becomes inaccurate in low-speed regions
Solution Approach 1:
The patent changes the detection parameter from absolute wheel speed to slip ratio (difference between drive wheel speed and driven wheel speed). This parameter transformation enables reliable slip detection even when absolute speed values are too low for conventional sensors to measure accurately, as the relative difference can be detected through torque sensor feedback.
2Productivity
If slip suppression control is delayed until wheel speeds become detectable, then unnecessary torque control is avoided, but drive wheel slipping occurs during the delay period
Solution Approach 1:
The patent implements preliminary slip suppression control by monitoring slip ratio from the moment acceleration begins, before wheel speeds reach detectable levels. The torque sensor detects slip conditions early, and torque control is applied proactively to prevent slipping, rather than waiting for conventional speed sensors to become operational.
Solution Approach 2:
The patent uses torque sensor feedback to continuously monitor the difference between drive wheel and driven wheel speeds, enabling real-time detection of slip conditions. This feedback mechanism allows the control system to respond immediately to slip tendencies and adjust torque application, maintaining both stability and acceleration performance.
3Reliability
If torque control is applied based on inaccurate slip detection, then vehicle stability is compromised, but acceleration performance also deteriorates due to unnecessary torque reduction
Solution Approach 1:
The patent introduces the torque sensor as an intermediary measurement device that indirectly detects slip conditions by measuring the torque difference between drive and driven wheels. This intermediary approach provides accurate slip detection without relying on direct wheel speed measurement, enabling precise torque control that maintains both stability and acceleration performance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Effectively suppresses drive wheel slipping across all speed regions, from undetectable low-speeds to detectable high-speeds, maintaining vehicle stability and preventing unnecessary torque control, thereby enhancing acceleration performance.
Implementation Method 1
a torque sensor that detects a torque applied to the drive wheels
Implementation Method 2
a slip state discriminator that discriminates the wheel speed based on the detected torque value
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
Provided is an electrically driven vehicle capable of suppressing drive wheel slipping, even in low-speed regions where wheel speeds are undetectable. The vehicle has driven wheels 7, 8 and drive wheels 3, 6, and the drive wheels 3, 6 are driven by electric motors 1, 4. The vehicle further includes a motor controller 22 which, if wheel speeds of the driven wheels 7, 8 that are detected by speed detectors 11, 12, or a body speed of the vehicle that is detected by a vehicle body speed detector 41 is less than a first setting value, regulates a torque that is output from the motors 1, 4, in order that wheel speeds of the drive wheels 3, 6 are less than a second setting value.