Regenerative Brake Torque Control Under Pitch and Drivetrain Dynamics
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Solution Overview
Problem
Existing cooperative braking systems for motor vehicles fail to accurately regulate regenerative braking torque, leading to wheel locking due to neglect of dynamic behavior and pitching of the vehicle, which cannot be prevented without significant latency in control responses.
Innovation Solution
A braking torque control device that includes a computing device to determine a setpoint for regenerative braking torque, taking into account the driving status, maximum axle braking torque, normal force due to pitching, and drive train dynamics, and controls the regenerative braking device to prevent wheel locking by optimizing the torque distribution between friction and regenerative braking systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If regenerative braking torque is increased to reduce braking distance, then braking efficiency is improved, but wheel locking occurs due to excessive torque
Solution Approach 1:
The system performs preliminary calculations of the maximum transmissible normal force and drivetrain dynamics before applying regenerative braking torque. The control unit predicts the optimal target torque value in advance, considering vehicle pitch, axle load, and drivetrain characteristics, thereby preventing wheel locking before it occurs rather than reacting after slip is detected
Solution Approach 2:
The system continuously monitors wheel slip conditions and adjusts the regenerative braking torque accordingly. When slip is detected, the control unit reduces the target torque value and communicates corrected values to the inverter, creating a closed-loop feedback system that maintains braking efficiency while preventing wheel locking
2Reliability
If regenerative braking torque is reduced to prevent wheel locking, then wheel slip is avoided, but braking distance increases
Solution Approach 1:
The system dynamically changes the target torque parameter based on real-time vehicle conditions including pitch angle, axle normal force, and drivetrain dynamics. By continuously adjusting the target regenerative braking torque to match the maximum transmissible force, the system maintains optimal braking efficiency across varying operating conditions without causing wheel locking
Solution Approach 2:
The system incorporates dynamic models of vehicle pitch and drivetrain behavior to predict how torque changes will affect wheel slip. By simulating the dynamic response of the mechanical drivetrain and vehicle body, the control unit determines torque values that achieve maximum braking force while accounting for the inertial and elastic characteristics of the drivetrain
3Reliability
If control response latency is reduced for faster torque adjustment, then wheel locking prevention is improved, but control precision decreases due to dynamic overshoot
Solution Approach 1:
The system applies beforehand cushioning by calculating compensatory factors for drivetrain elasticity and inertia before torque changes are executed. The control unit predicts the overshoot that will occur due to drivetrain dynamics and adjusts the target torque value in advance to compensate for this effect, ensuring precise torque control even with rapid response times
Solution Approach 2:
The system applies preliminary anti-action by anticipating and counteracting the elastic rebound and inertial overshoot of the drivetrain before they occur. By calculating the expected dynamic response and applying opposing corrective torque adjustments in advance, the system prevents torque oscillations and maintains precise control during rapid braking maneuvers
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 solution effectively reduces braking distance during emergency braking by predictive torque control, avoiding wheel locking and maximizing regenerative braking torque without exceeding the maximum transferable normal force, thus enhancing the overall braking efficiency and safety.
Implementation Method 1
the vehicle's electric motor is operated as a generator. Advantageously, the kinetic energy during braking is converted into storable electrical energy
Implementation Method 2
conventional hydraulic friction brakes, which apply a frictional braking torque to one wheel of the vehicle
Data Source
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AI summary
The invention relates to a braking torque control device for a motor vehicle, wherein the motor vehicle comprises a first brake device and a second brake device. The first brake device is configured to apply a frictional braking torque to at least one wheel of the motor vehicle. The second brake device is configured to apply a regenerative braking torque to at least one wheel of the motor vehicle. The braking torque control device comprises an interface and a processing device. The interface receives information relating to a driving state of the motor vehicle. The processing device determines a setpoint value for the regenerative braking torque, wherein said processing device takes into consideration the received information relating to the driving state of the motor vehicle, a maximum axle braking torque that can be transmitted via the respective drive axles of the motor vehicle to an underlying surface taking into consideration a normal force acting on each of the drive axles owing to the pitching behaviour of the vehicle, and dynamics of a drivetrain of the respectively driven axles of the motor vehicle. The processing device is furthermore configured to actuate the second brake device via the interface such that the applied regenerative braking torque is adjusted by control to the setpoint value determined by the processing device.