In-Wheel Motor Braking Force Control via Electromagnetic Substitution
Solution Overview
Problem
Conventional braking control systems for electric vehicles face issues with wheel locking during braking due to backlash in power transmission systems, leading to unsatisfactory control performance and noise generation.
Innovation Solution
A braking force control apparatus that includes an electrical force generation mechanism, road surface state detection, lock tendency determination, and braking force computation to apply electromagnetic and mechanical braking forces effectively, avoiding alternating states that cause wheel locking and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the drive motor is operated through regeneration control and power running control to increase and decrease torque, then braking force control is achieved, but backlash in the power transmission system causes time lag and unsatisfactory control performance
Solution Approach 1:
The patent replaces the mechanical regeneration braking system with an electromagnetic braking system. The electromagnetic braking force generation mechanism directly applies braking force to the wheel through electromagnetic fields, eliminating the need for mechanical power transmission components like reduction gears that produce backlash. This substitution resolves the time lag issue while maintaining effective braking force control.
2Ease of operation
If the drive motor is operated through regeneration control and power running control, then torque control is achieved, but backlash generates noise and imparts unnatural sensation to driver
Solution Approach 1:
The patent eliminates mechanical backlash by substituting the mechanical regeneration braking system with an electromagnetic braking system. The electromagnetic braking force generation mechanism produces braking force directly through electromagnetic fields without mechanical power transmission, thereby eliminating noise generation from backlash while maintaining effective braking control capability.
3Stability of the object's composition
If hydraulic braking force is maintained at constant value during ABS control, then mechanical braking stability is achieved, but wheel locking may occur on low friction surfaces
Solution Approach 1:
The patent makes the braking force dynamically adaptive by introducing an electromagnetic braking force generation mechanism that can independently adjust braking force based on real-time wheel slip detection and road surface conditions. This dynamic adjustment capability allows the system to prevent wheel locking on low friction surfaces while maintaining stability on high friction surfaces, resolving the contradiction between stability and reliability.
Solution Approach 2:
The patent changes the braking force parameter dynamically by using an electromagnetic braking system that can independently modulate braking force magnitude based on wheel slip ratio and road surface friction coefficient. This parameter adjustment capability enables the system to adapt to varying road conditions, preventing wheel locking while maintaining braking stability.
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
The system ensures high responsiveness and precise control to prevent wheel locking, reduces noise, and maintains proper braking performance even with backlash in the power transmission system.
Implementation Method 1
an electrical force generation mechanism which applies electromagnetic driving force or electromagnetic braking force to a wheel
Implementation Method 2
a braking force generation mechanism which applies mechanical braking force
Data Source
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AI summary
A braking force control apparatus for a vehicle estimates the friction coefficient µ of a road surface as the state of the road surface on which the vehicle travels, and determines (computes) an ideal braking force µW (target braking force) by making use of the estimated road surface friction coefficient µ. When the estimated road surface friction coefficient µ is equal to or greater than a predetermined friction coefficient µ0, the braking force control apparatus operates an in-wheel motor (electrical force generation mechanism) in a regeneration state to thereby generate a motor braking torque Tmr, and causes a friction brake mechanism (braking force generation mechanism) to generate a frictional braking force Bf computed by subtracting the motor braking torque Tmr from the ideal braking force µW. Meanwhile, when the estimated road surface friction coefficient µ is less than the predetermined friction coefficient µ0, the braking force control apparatus operates the in-wheel motor (electrical force generation mechanism) in a power running state to thereby generate a motor driving torque Tmc, and causes the friction brake mechanism (braking force generation mechanism) to generate a frictional braking force Bf computed by adding the motor driving torque Tmc to the ideal braking force µW.