One-Pedal Braking Control With Regen and Friction Torque Blending
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Solution Overview
Problem
In one-pedal driving mode of electric vehicles, the inconsistency in braking performance occurs when the powertrain braking torque capacity is insufficient, leading to varying deceleration rates due to reliance solely on regenerative braking, which is not effectively supplemented by friction brakes in existing systems.
Innovation Solution
A vehicle controller is programmed to command torques from both the powertrain and friction brakes to ensure consistent braking by determining the target braking torque based on the accelerator pedal position, using the powertrain for primary braking and supplementing with friction brakes when the powertrain capacity is inadequate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If regenerative braking alone is used in one-pedal driving mode, then battery charging efficiency is improved, but braking performance consistency deteriorates when powertrain capacity is insufficient
Solution Approach 1:
The patent combines regenerative braking and friction braking into a unified braking system. The controller dynamically coordinates both braking mechanisms to work together, merging their advantages to achieve both energy recovery and consistent braking performance across all operating conditions.
Solution Approach 2:
The controller acts as an intermediary that manages the transition and coordination between regenerative braking and friction braking. It monitors powertrain capacity in real-time and intermediates the braking force distribution, switching between or combining the two braking methods as needed to maintain performance consistency.
2Reliability
If friction brakes are added to supplement powertrain braking, then braking performance consistency is improved, but device complexity increases
Solution Approach 1:
The braking system is designed with multi-functionality where the friction brakes serve dual purposes: providing supplemental braking force when powertrain capacity is insufficient and enabling complete stops. The controller universally manages both braking systems through a single coordination logic, reducing operational complexity despite the added hardware.
3Reliability
If controller coordination of multiple braking sources is implemented, then braking performance consistency is improved, but control complexity increases
Solution Approach 1:
The control system dynamically adjusts the braking force distribution between powertrain and friction brakes based on real-time conditions. The controller continuously monitors powertrain capacity, vehicle speed, and braking demand, dynamically optimizing the coordination strategy to maintain performance consistency while adapting to changing operating conditions.
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 ensures consistent braking performance by utilizing the powertrain for primary braking and friction brakes to account for powertrain capacity shortfalls, maintaining consistent deceleration rates and enhancing battery charging efficiency.
Implementation Method 1
Many electrified vehicles are capable of regenerative braking to recharge the battery by converting mechanical power into electrical power
Implementation Method 2
command torques from the powertrain and the friction brakes such that the target braking torque is satisfied
Data Source
AI summary
A vehicle includes a powertrain having an electric machine configured to power driven wheels, an accelerator pedal, and friction brakes. A vehicle controller is programmed to, with the vehicle being in a one-pedal driving mode: in response to a braking torque capacity of the powertrain exceeding a target braking torque that is based on a position of the accelerator pedal, command a torque, that is equal to the target braking torque, from the powertrain such that the vehicle is slowed using the powertrain without application of the friction brakes, and, in response to the braking torque capacity of the powertrain being less than the target braking torque, command torques from the powertrain and the friction brakes such that the target braking torque is satisfied and the vehicle is slowed using the powertrain and the friction brakes.