Regenerative Torque Limit Control for Smooth Brake Transition
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Solution Overview
Problem
Hybrid electric vehicles face challenges in smoothly transitioning from regenerative braking to friction braking, leading to potential disruptions in vehicle deceleration and increased wear on friction brakes, due to the coordination of multiple control logics with different objectives during the regenerative torque blend-out process.
Innovation Solution
A vehicle system with a powertrain and controllers that adjust the regenerative torque limit based on shaft speed and predicted friction brake fill-in rate, ensuring a coordinated blend-out of regenerative torque and friction braking torque to maintain smooth deceleration and reduce brake wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If regenerative torque is reduced during blend-out to coordinate with friction braking, then smooth transition is improved, but regenerative energy recovery is reduced
Solution Approach 1:
The regenerative torque limit is dynamically adjusted based on real-time shaft speed and predicted friction brake fill-in rate. The controller continuously modifies the torque limit during the blend-out process to coordinate the transition between regenerative and friction braking, optimizing both smoothness and energy recovery at different operating conditions.
Solution Approach 2:
The system changes the regenerative torque limit parameter as a function of shaft speed and friction brake fill-in rate. By adjusting this parameter during the blend-out duration, the system achieves coordinated transition while maximizing energy recovery within the constraints of friction brake capacity.
2Adaptability or versatility
If multiple independent control logics are used for blend-out coordination, then control flexibility is improved, but system complexity increases
Solution Approach 1:
The patent merges multiple independent control logics into a unified control framework. The single controller integrates regenerative braking control, friction braking control, and torque converter clutch control into one coordinated system, eliminating the need for separate control logics and their associated arbitration mechanisms.
Solution Approach 2:
The controller performs multiple functions simultaneously: it manages regenerative torque limits, coordinates friction brake fill-in, predicts clutch unlock speed, and adjusts blend-out rate. This multi-functional approach replaces multiple specialized control logics with one universal controller that handles all blend-out coordination tasks.
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 enables a seamless transition from regenerative braking to friction braking, enhancing driver satisfaction and reducing brake wear by optimizing the blend-out process based on vehicle speed and torque converter clutch unlock speed.
Implementation Method 1
The electric motor functions as a generator and absorbs energy generated as a result of the powertrain braking and converts the energy to electric energy
Data Source
AI summary
A vehicle includes a powertrain and at least one controller programmed to, in response to a brake request and a shaft speed associated with a speed of the vehicle achieving a starting speed that is defined by a torque of the powertrain that changes with brake demand at a given shaft speed, reduce a regenerative torque limit that constrains regenerative braking torque over a blend-out duration based on the shaft speed.