Electric Axle and Brake Control for Regenerative Braking Limits
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Solution Overview
Problem
Heavy commercial vehicles with electric propulsion face challenges in efficiently managing actuator coordination and energy efficiency, particularly when regenerative braking is insufficient to meet regulatory braking forces, and power-to-mass ratios are limited, leading to the need for a more adaptive and energy-efficient control of motion support systems.
Innovation Solution
A method and controller that utilize quadratic programming (QP) to optimize the control of independently controlled actuators, including electric motors and service brakes, by selecting predefined drive modes and solving QP problems to minimize power loss or prioritize performance, while adhering to actuator limits, suitable for vehicles with diverse uses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If regenerative braking is used to decelerate the vehicle, then energy efficiency is improved through energy recovery, but the braking force is insufficient to meet regulatory minimum requirements
Solution Approach 1:
The patent combines regenerative braking and service braking systems into a unified braking control system. The service brake controller coordinates both braking mechanisms to achieve regulatory minimum braking force while maximizing energy recovery through regenerative braking, resolving the contradiction between energy efficiency and sufficient braking force.
Solution Approach 2:
The braking system uses a composite approach by integrating two different braking mechanisms (regenerative braking with electromagnetic drag and service braking with friction) to achieve the desired performance characteristics that neither system could provide alone.
2Adaptability or versatility
If multiple independently controlled actuators are used at respective axles, then adaptability to different vehicle uses is improved, but actuator coordination complexity increases
Solution Approach 1:
The service brake controller is designed to perform multiple functions: coordinating regenerative and service braking, managing energy recovery, ensuring regulatory compliance, and adapting to different vehicle configurations and uses. This multi-functional design handles the coordination complexity centrally while maintaining versatility.
Solution Approach 2:
The system uses feedback from vehicle state sensors and actuator status to dynamically adjust the coordination of multiple actuators. The service brake controller continuously monitors and adjusts actuator commands based on actual vehicle behavior, simplifying the coordination of independently controlled actuators across different axles.
Data Source
AI summary
A method of controlling a motion support system (MSS) in a heavy commercial vehicle comprising repeatedly selecting a current drive mode; solving a quadratic programming (QP) problem related to optimal control of independently controlled MSS actuators in accordance with a current state of the vehicle and subject to constraints representing actuator limits, wherein the actuators include at least two electric motors at respective axles and a set of service brakes; and utilizing a solution of the QP problem for controlling the MSS. The selectable drive modes include a first drive mode, in which the QP problem represents a control allocation problem for the MSS, and a second drive mode, in which the QP problem minimizes power loss in the MSS. The QP problem in the second drive mode includes relationships between power loss and torque for at least two of the actuators, especially smooth approximate relationships.