Electric Trailer Braking Control With Battery Charge Margin
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Solution Overview
Problem
Heavy-duty electric vehicles lack effective endurance braking systems, as conventional auxiliary brakes are not applicable, and existing regenerative braking systems are inefficient for extended downhill driving.
Innovation Solution
A vehicle control unit (VCU) and electrical energy storage system (EESS) manage energy absorption and dissipation to maintain a desired energy absorption capability, enabling regenerative braking and endurance braking by maintaining a margin below full charge, allowing for efficient and safe downhill driving.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If regenerative braking is used to recover energy during downhill driving, then energy efficiency is improved, but the energy absorption capability of the EESS may be insufficient for extended periods of downhill driving
Solution Approach 1:
The control unit proactively manages the EESS state of charge before downhill driving begins, maintaining a predetermined margin from full charge to ensure sufficient energy absorption capability is available when endurance braking is needed, rather than waiting until the braking situation arises
Solution Approach 2:
The control unit acts as an intermediary that coordinates between the EESS and electric machine, managing energy flow and state of charge to balance energy recovery opportunities with the need to maintain sufficient absorption capability for future braking events
2Quantity of substance
If the EESS is maintained at full charge to maximize energy storage, then energy availability is improved, but the ability to absorb regenerative energy during downhill driving is reduced
Solution Approach 1:
The control unit dynamically adjusts the state of charge parameter of the EESS, maintaining it within a specific range below full charge to optimize the balance between stored energy availability and energy absorption capability for regenerative braking
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
Ensures safe and efficient endurance braking by maintaining a margin in the EESS to absorb energy, preventing overheating and ensuring the vehicle can sustain prolonged downhill driving without losing braking capability.
Implementation Method 1
at least one electric machine arranged for regenerative braking, wherein the electric machine is arranged to generate an electrical output current during regenerative braking of the vehicle unit
Implementation Method 2
an electrical energy storage system (EESS)... control an energy dissipation from the EESS to maintain an energy absorption capability of the EESS
Data Source
AI summary
A vehicle unit comprising a vehicle control unit, VCU, an electrical energy storage system, and at least one electric machine arranged for regenerative braking, wherein the electric machine generates an electrical output current during regenerative braking, wherein the control unit is arranged to obtain a desired energy absorption capability value of the vehicle unit and to control an energy dissipation from the EESS to maintain an energy absorption capability of the EESS above the desired energy absorption capability value.