In-Wheel Motor Traction Control With Dual-Loop Torque Response
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Solution Overview
Problem
Traction control systems for electric vehicles with in-wheel motors face performance limitations due to communication lag between the central control unit and in-wheel motors, leading to delayed torque actuation and potential wheel slipping or spinning.
Innovation Solution
A dual-loop control system is implemented, where a slow loop runs on a central controller to calculate speed limits for in-wheel motors and a fast speed control loop operates on the in-wheel motor controller, allowing instantaneous torque actuation and maintaining speed limits within calculated bounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a central control unit actuates torque centrally through ABS valves and engine torque delivery systems, then torque can be applied to wheels via transmission/driveline, but there is a lag between central actuation and application of torque to the road surface
Solution Approach 1:
The patent divides the traction control system into two independent control loops: a slow loop on the central controller that calculates speed limits, and a fast loop on the in-wheel motor controller that executes torque actuation. This segmentation allows the fast loop to respond immediately to speed deviations without waiting for central controller communication, eliminating the communication lag while maintaining centralized speed limit management.
2Speed
If in-wheel electric motors are used to move torque actuation functionality to the wheel, then torque response time is improved, but communication between central traction control unit and in-wheel motors still imposes performance limitations
Solution Approach 1:
The patent implements a dynamic control architecture where the in-wheel motor controller operates autonomously in a fast control loop, making real-time torque adjustments based on local speed measurements. This dynamic independence allows the system to maintain reliable traction control performance by executing torque actuation immediately when needed, without being constrained by communication cycles with the central controller.
3Productivity
If a dual-loop control system is implemented with fast speed control on in-wheel motor controller, then torque actuation is instantaneous and speed limits are maintained, but system complexity increases
Solution Approach 1:
The in-wheel motor controller is equipped with the capability to independently execute the fast speed control loop using local sensors and processors. This self-service approach allows the controller to perform real-time torque adjustments without requiring complex centralized coordination, reducing the overall system complexity while maintaining high traction control effectiveness through distributed intelligence.
Data Source
AI summary
A traction control system for a vehicle having a first wheel driven by a first electric motor including a first set of coil windings, the system comprising a first controller arranged to control current in the coil windings for generating a drive torque for driving the first wheel, and a second controller arranged to determine a maximum wheel velocity based on a first slip ratio value for the first wheel and the vehicle velocity and a minimum wheel velocity based on a second slip ratio value for the first wheel and the vehicle velocity. The second controller communicates to the first controller the maximum and minimum values and a torque demand value corresponding to a drive torque for driving the first wheel. The first controller controls current in the coil windings to generate a drive torque based on the maximum and minimum wheel velocity and torque demand values from the second controller.