Electric Vehicle Slip Control via Motor Feedback
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Solution Overview
Problem
Existing control devices for electric vehicles face challenges in accurately detecting and controlling slip due to low angular resolution of wheel speed sensors, leading to detection delays and vibrations, which hinder high-speed control and appropriate slip management.
Innovation Solution
A control device that utilizes a rotation speed detecting unit with high angular resolution to calculate a target rotation speed for the drive wheel and performs slip control by feedback control based on the difference between the motor rotation speed and the target rotation speed, effectively reducing detection delays and vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If wheel speed sensor with low angular resolution is used for slip detection, then device complexity is reduced, but measurement precision deteriorates leading to detection delays
Solution Approach 1:
The patent replaces the mechanical wheel speed sensor system with an electrical measurement system. Specifically, it uses a rotation speed detecting unit that measures the rotation speed of the motor shaft electrically, and derives wheel speed information from motor torque and rotation speed data through calculation, eliminating the need for physical wheel speed sensors with limited angular resolution.
2Device complexity
If wheel speed sensor is used for slip detection, then device complexity is reduced, but detection speed deteriorates due to detection delays
Solution Approach 1:
The system performs preliminary measurement by continuously monitoring motor rotation speed and torque, which are directly correlated with wheel speed. This preliminary data collection enables the calculation unit to rapidly compute wheel speed and detect slip conditions without waiting for wheel speed sensor signals, significantly reducing detection time.
3Measurement precision
If feedback control is applied for slip control, then control precision is improved, but device complexity increases
Solution Approach 1:
The patent implements feedback control by continuously comparing the calculated wheel speed (derived from motor rotation speed and torque) with the target wheel speed, detecting slip conditions, and adjusting motor torque accordingly. The slip control unit uses this feedback loop to maintain optimal traction by dynamically modifying motor output based on real-time slip detection.
Data Source
AI summary
A control device of an electric vehicle includes: a target rotation speed calculation unit that calculates a target rotation speed of a drive wheel based on a vehicle body speed; and a slip control unit that detects a slip of the drive wheel when a wheel speed exceeds the target rotation speed of the drive wheel and that controls motor torque of the motor in such a manner that the wheel speed becomes an appropriate rotation speed in detection of the slip. Further, the slip control unit controls the motor torque by feedback control according to a difference between the rotation speed of the motor and the target rotation speed of the drive wheel in detection of the slip.