Deployable Braking Resistor for Full-Battery Regen Control
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Solution Overview
Problem
Conventional electrified vehicles face issues with inconsistent driving experiences due to disabled regenerative braking when the battery is fully charged, leading to unfamiliar feedback and brake wear, especially when regenerative braking is undesirable.
Innovation Solution
A deployable and retractable resistor that converts regenerative motor power to heat when the battery is fully charged, maintaining consistent braking feedback by dissipating power through a deployable resistor and adding aerodynamic drag when needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If regenerative braking is disabled when the battery is fully charged, then the battery system is protected from overcharging, but the driving experience becomes inconsistent and brake wear increases
Solution Approach 1:
A deployable resistor is introduced as an intermediary component to dissipate excess regenerative braking energy when the battery is fully charged. The resistor acts as a mediator between the regenerative braking system and the battery, allowing the system to maintain consistent braking feedback while protecting the battery from overcharging by converting excess energy to heat.
Solution Approach 2:
The resistor is designed to be deployable and retractable based on real-time battery charge state. When the battery reaches full charge, the resistor deploys to provide additional drag and dissipate energy; when the battery can accept charge, the resistor retracts. This dynamic adjustment maintains consistent driving experience while protecting the battery.
2Ease of operation
If a deployable resistor is used to dissipate regenerative power, then consistent braking feedback is maintained, but aerodynamic drag increases when the resistor is deployed
Solution Approach 1:
The resistor is designed to deploy only when necessary (when the battery is fully charged and cannot accept regenerative power). During normal operation, the resistor remains retracted to minimize aerodynamic drag. This dynamic deployment strategy maintains braking feedback consistency while minimizing the harmful aerodynamic drag effect.
Solution Approach 2:
The resistor is positioned in the driveline where it can provide localized drag control without significantly impacting overall vehicle aerodynamics. By concentrating the drag effect only where needed for braking feedback and energy dissipation, the system minimizes unnecessary aerodynamic penalties.
3Reliability
If regenerative braking is completely disabled when the battery is full, then battery overcharging is prevented, but energy recovery efficiency is reduced
Solution Approach 1:
The deployable resistor serves as an intermediary energy dissipation path when the battery cannot accept charge. Instead of completely disabling regenerative braking, the system routes excess energy through the resistor, which converts it to heat. This maintains energy recovery functionality while protecting the battery, thereby reducing energy loss compared to complete disablement.
Solution Approach 2:
The system converts the potentially harmful effect of excess energy (which cannot be stored in a full battery) into a beneficial outcome by using the resistor to dissipate it. The resistor transforms excess electrical energy into thermal energy, preventing battery damage while maintaining braking functionality and improving overall energy management.
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
Maintains consistent regenerative braking feedback and reduces brake wear by converting excess power to heat, ensuring a smooth driving experience regardless of battery charge state.
Implementation Method 1
regenerative power is directed to the regenerative system resistor and dissipated as heat
Implementation Method 2
The fan is configured to rotate from ambient airflow during movement of the electrified vehicle and thereby dissipate heat
Implementation Method 3
In the deployed position, the regenerative system resistor adds aerodynamic drag to the electrified vehicle
Data Source
AI summary
A regenerative braking system for an electrified vehicle includes a battery system, an electric motor and a regenerative system resistor. The battery system selectively stores and delivers power. The electric motor is powered by the battery system and transfers drive torque to a driveline for propulsion of the vehicle and that selectively directs regenerative power in a first mode to the battery system during regenerative braking. The regenerative system resistor is selectively moveable between a first position during the regenerative braking in the first mode and a second position where regenerative power is directed to the regenerative system resistor and dissipated as heat in a second mode.