Regenerative Braking Control for Flat Towed Electric Vehicles
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Solution Overview
Problem
Existing braking systems in electric vehicles do not effectively utilize regenerative braking when the vehicle is being towed, leading to inefficiencies in energy conservation and increased load on the towing vehicle during acceleration and deceleration.
Innovation Solution
A braking system that includes a sensor to measure tensile loads in the tow member connecting a towing vehicle to a towed vehicle, with a computer controlling regenerative braking based on these measurements to maintain a constant tensile load, thereby optimizing energy usage and reducing drag.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If regenerative braking is activated during towing, then energy is conserved through battery charging, but the towing vehicle experiences increased load and reduced drivability
Solution Approach 1:
The system continuously monitors tensile load in the tow member via a load sensor and uses this feedback to dynamically adjust regenerative braking torque. When tensile load exceeds a threshold, the control system reduces or disables regenerative braking to prevent excessive drag on the towing vehicle, while allowing regenerative braking when load is within acceptable ranges to maximize energy recovery.
Solution Approach 2:
The braking system transitions from a static, fixed-state regenerative braking approach to a dynamic, adaptive system that continuously adjusts braking torque based on real-time tensile load conditions. This enables the system to optimize the balance between energy recovery and towing vehicle performance by varying regenerative braking intensity according to actual loading conditions.
2Force
If regenerative braking is disabled during towing, then the towing vehicle experiences reduced load and improved drivability, but energy is not conserved and the towed vehicle's battery is not charged
Solution Approach 1:
The load sensor provides continuous feedback on tensile load conditions, enabling the control system to determine optimal moments to activate regenerative braking. When feedback indicates low or moderate tensile load, the system activates regenerative braking to capture energy; when feedback shows high tensile load, the system disables or reduces regenerative braking to minimize drag, thus optimizing the trade-off between energy conservation and towing vehicle performance.
Solution Approach 2:
The system changes the operational parameters of the braking system based on towing conditions by adjusting the threshold for regenerative braking activation and modifying braking torque magnitude. This allows the same braking system to operate in multiple modes: full regenerative braking during normal operation, reduced regenerative braking during light towing, and disabled regenerative braking during heavy towing or critical load conditions.
3Loss of energy
If a sensor and control system are added to manage regenerative braking during towing, then energy efficiency is optimized, but device complexity increases
Solution Approach 1:
The load sensor and control system serve multiple functions: they monitor towing conditions for drivability optimization, enable dynamic regenerative braking control for energy efficiency, and provide data for potential future functionalities such as adaptive cruise control or collision avoidance. This multi-functionality justifies the added complexity by delivering multiple benefits from a single integrated system.
Solution Approach 2:
The control system automatically manages regenerative braking based on load sensor feedback without requiring driver intervention or complex user interfaces. The system self-adjusts braking torque based on real-time conditions, eliminating the need for manual controls or complex user-programmable settings, thereby reducing operational complexity while maintaining energy efficiency.
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 system enhances energy efficiency by dynamically adjusting regenerative braking and motor assist to maintain a constant tensile load, reducing the load on the towing vehicle and improving drivability during towing.
Implementation Method 1
A sensor is provided that senses a tensile load in the tow member. The tensile load may include tension forces and/or compression forces exerted on the tow member.
Implementation Method 2
Electric vehicles typically utilize regenerative braking, in which a traction motor serves as a generator to convert the kinetic energy of the vehicle into electric energy that is stored in a traction battery.
Data Source
AI summary
A towed vehicle is towed by a towing vehicle. The towed vehicle includes a motor/generator for both regenerative braking and for powering wheels. A tow member connects the towed vehicle to the towed vehicle. A sensor measures or infers the tension and compression in the tow member. A computer communicates with the sensor and with the motor/generator. The computer commands the motor/generator to either utilize regenerative braking or provide assistance in propulsion of the towed vehicle based upon the tension and compression forces in the tow member.