Hybrid Drive Train Braking Torque Distribution Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing hybrid drive systems for motor vehicles face challenges in efficiently distributing braking torque between electric machines and wear-free permanent brakes to achieve high dynamic response and controlled braking, particularly in ensuring consistent braking torque delivery as the drive output speed decreases.
Innovation Solution
The method involves initially providing braking torque exclusively through the electric machine and then transferring it to the wear-free permanent brake in a controlled manner, ensuring the sum of torques from both components matches the required braking torque, with the electric machine taking over if the permanent brake can no longer provide sufficient torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If braking torque is provided exclusively by the electric machine at the beginning of braking, then high dynamic response and short reaction time are achieved, but the electric machine cannot maintain sufficient braking torque as drive output speed decreases
Solution Approach 1:
The control method initiates braking torque provision exclusively through the electric machine at the beginning of braking operations. This preliminary action leverages the electric machine's high dynamic response characteristics to achieve rapid braking initiation, establishing a foundation for subsequent controlled torque transfer to the permanent brake as speed decreases
Solution Approach 2:
The system dynamically transitions braking torque provision from the electric machine to the permanent brake based on drive output speed. At higher speeds, the electric machine provides braking torque with superior response characteristics, while at lower speeds, the permanent brake assumes primary braking responsibility to maintain consistent torque delivery, creating a speed-dependent dynamic distribution strategy
2Reliability
If braking torque is transferred from the electric machine to the permanent brake as speed decreases, then braking torque consistency is maintained, but the system complexity increases due to coordinated control requirements
Solution Approach 1:
The control method merges the braking functions of the electric machine and permanent brake into a coordinated system. By integrating both braking sources and implementing controlled torque distribution between them based on speed conditions, the system achieves consistent braking torque delivery while utilizing the complementary strengths of each braking component
Solution Approach 2:
The system changes the distribution parameter of braking torque between the electric machine and permanent brake as a function of drive output speed. This parameter-based control strategy automatically adjusts the braking torque split according to operating conditions, maintaining braking consistency without requiring complex manual intervention or overly sophisticated control algorithms
3Reliability
If the electric machine provides braking torque at low speeds, then braking torque consistency is maintained, but energy losses increase due to electrical braking at inappropriate operating conditions
Solution Approach 1:
The control method changes the primary braking source based on drive output speed parameters. At low speeds, the system transitions from electric machine braking to permanent brake braking, as the permanent brake becomes more efficient and appropriate for low-speed operations, thereby reducing energy losses associated with electrical braking under unsuitable conditions
Solution Approach 2:
Each braking component serves itself according to its optimal operating range. The electric machine handles braking at higher speeds where regenerative or electrical braking is effective, while the permanent brake handles braking at lower speeds where mechanical friction braking is more efficient, allowing each component to operate in its self-optimal regime and minimizing overall energy losses
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
This approach allows for rapid and dynamic initial braking torque response, controlled torque distribution, and reliable braking torque maintenance throughout the braking process, preventing over-braking and oscillations in the drive-train.
Implementation Method 1
the braking torque is provided exclusively by an electric machine (2) of the hybrid drive system (3) and is delivered to a drive output (4)
Implementation Method 2
at least one wear-free permanent brake (6), namely a so-termed engine brake or a retarder of the drive-train
Data Source
AI summary
A method for operating a drive-train of a motor vehicle with a drive aggregate in the form of a hybrid drive system (3) which comprises at least one electric machine (2), an internal combustion engine (1), a transmission (5), a drive output (4) and a brake system which comprises at least one wear-free permanent brake (6). When a braking torque is required, the braking torque is distributed between the electric machine (2) and the wear-free permanent brake (6). At the beginning of a braking torque demand, the required brake torque is provided exclusively by the electric machine (2). Thereafter, as a function of characteristics of the wear-free permanent brake, the braking torque demand is transferred, in a controlled manner, from the electric machine to the wear-free permanent brake (6) so that the sum of the braking torques provided at the drive output (4) corresponds to the required braking torque.