Four-Wheel Drive Electric Vehicle Stability Control via Differential Braking
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Solution Overview
Problem
Existing stability control systems for four-wheel drive electric vehicles are inadequate in preventing rollover accidents, particularly during sudden maneuvers, as they rely on slow hydraulic braking and cannot quickly respond to changing vehicle states.
Innovation Solution
A stability control system that includes a vehicle controller with first and second stability control units, using lateral acceleration signals to calculate a lateral load transfer ratio and apply braking forces to specific wheels, such as the outside front and inside rear wheels, to maintain vehicle stability through regenerative braking and differential torque control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If traditional hydraulic braking is used for stability control, then the system structure is simple, but the response time is slow and cannot quickly respond to changing vehicle states
Solution Approach 1:
The patent replaces the traditional hydraulic braking system with an electric braking system using motor controllers. The motor controllers can independently control each wheel's braking force through electrical signals, achieving rapid response times without the mechanical delays inherent in hydraulic systems. This substitution enables the stability control system to quickly detect and respond to vehicle state changes while maintaining structural simplicity through electronic control architecture.
2Stability of the object's composition
If braking force is applied to all wheels uniformly, then the control logic is simple, but the vehicle stability cannot be effectively improved during rollover-prone maneuvers
Solution Approach 1:
The patent implements differential braking control where each wheel receives individually calculated braking forces based on its specific position and the vehicle's dynamic state. The control system calculates lateral load transfer ratios for each wheel and applies braking forces selectively to outside front and inside rear wheels during rollover-prone maneuvers. This localized control approach significantly improves vehicle stability by counteracting the specific rollover tendency while managing control logic complexity through systematic calculation methods.
Solution Approach 2:
The stability control system divides the vehicle into four independent wheel control zones, each with its own braking force calculation and application. By segmenting the braking control rather than applying uniform braking to all wheels, the system can precisely counteract lateral load transfer and rollover tendencies at specific vehicle corners, achieving superior stability control through distributed independent wheel management.
3Use of energy by moving object
If regenerative braking is used instead of hydraulic braking, then energy efficiency is improved, but the braking force control precision may be reduced
Solution Approach 1:
The patent utilizes the motor controllers' ability to precisely control electrical parameters (current, voltage, duty cycle) to regulate braking forces. By changing electrical control parameters rather than relying solely on mechanical hydraulic pressure, the system achieves both energy recovery through regenerative braking and precise braking force control. The motor controllers can independently adjust each wheel's braking torque with high precision through electronic modulation, maintaining control accuracy while improving energy efficiency.
Data Source
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AI summary
The embodiments of the present application disclose a stability control system and a stability control method for a four-wheel drive electric vehicle and the four-wheel drive electric vehicle. In the stability control system, when the lateral acceleration is equal to or greater than an acceleration threshold, at least one of a first braking force signal, a second braking force signal, a first logic signal and a second logic signal is obtained. When the first logic signal is obtained, the body of the electric vehicle is controlled to keep stable. When the first braking force signal and the second logic signal are obtained, a motor is controlled to apply braking force to an outside front wheel. When the second braking force signal and the second logic signal are obtained, motors are controlled to apply braking force to the outside front wheel and an inside rear wheel.