Fail-Safe Battery Relay Control for Eco-Friendly Vehicles
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Solution Overview
Problem
Eco-friendly vehicles face issues with maintaining vehicle driving when there are data communication problems in the battery management system, leading to uncontrolled battery discharge and potential vehicle shutdown due to lack of state of charge confirmation.
Innovation Solution
A fail-safe apparatus and method that uses an alternative signal, such as capacity voltage from a power converter or motor controller, to control battery charging and discharging, ensuring safe operation by monitoring voltage thresholds and inhibiting or allowing charging and discharging accordingly, and utilizing a hybrid starter generator to maintain vehicle functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the battery management system monitors state of charge through CAN communication, then the battery state can be accurately managed, but communication errors cause uncontrolled discharge and vehicle shutdown
Solution Approach 1:
The patent introduces a voltage monitoring mechanism as an intermediary to indirectly assess battery state of charge when CAN communication fails. The vehicle controller monitors voltage at the battery relay terminal, using this voltage information as a mediator to determine whether to maintain battery connection or disconnect, thereby preventing uncontrolled discharge without requiring direct SOC communication from the BMS.
Solution Approach 2:
The system implements a feedback loop where the vehicle controller continuously monitors battery terminal voltage and compares it against threshold values. Based on this feedback, the controller automatically adjusts battery relay control decisions - maintaining connection when voltage indicates sufficient charge, or disconnecting when voltage drops below thresholds, thus creating a self-regulating mechanism that operates independently of BMS communication.
2Reliability
If the main battery relay is forcibly opened to prevent overdischarge damage, then battery safety is protected, but vehicle driving capability is lost due to insufficient power
Solution Approach 1:
The patent makes the battery relay control dynamic rather than static. Instead of forcibly opening the relay upon communication error, the vehicle controller continuously monitors battery terminal voltage and dynamically adjusts relay state - keeping it closed when voltage remains above threshold (maintaining driving capability) and opening it only when voltage drops below threshold (preventing overdischarge). This dynamic control allows the system to adapt to changing battery conditions in real-time.
Solution Approach 2:
The system changes the control parameter from a binary communication-based approach to a continuous voltage-based approach. By monitoring voltage as a continuous parameter and comparing it against predefined thresholds, the system can make nuanced decisions about battery relay control, maintaining operation within safe voltage ranges while maximizing available driving capability throughout the charge cycle.
3Ease of operation
If the vehicle operates in limp home mode with engine driving, then limited mobility is maintained, but continuous power consumption leads to battery overdischarge
Solution Approach 1:
The system enables self-service by allowing the vehicle to autonomously manage its own battery protection without external BMS communication. The vehicle controller independently monitors battery voltage and controls the battery relay based on predefined voltage thresholds, creating a self-regulating mechanism that prevents overdischarge during limp home operation. This self-service capability ensures battery protection even when the primary BMS communication path is unavailable.
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
This solution allows eco-friendly vehicles to continue driving by managing battery state through alternative signals, preventing sudden shutdowns and ensuring safety by avoiding overcharging or overdischarging, thus maintaining vehicle operation even with data communication errors in the battery management system.
Implementation Method 1
a power converter configured to convert power supplied from the main battery into power for charging an auxiliary battery
Implementation Method 2
a hybrid starter generator configured to start an engine and charge the main battery
Data Source
AI summary
The fail safe apparatus for an eco-friendly vehicle includes: a main battery to supply driving power of a vehicle; a battery controller to manage a state of charge of the main battery; a power converter to convert power supplied from the main battery into power for charging an auxiliary battery; a motor controller to drive a motor with the power supplied from the main battery; a hybrid starter generator to start an engine and charge the main battery; and a vehicle controller to monitor a capacity voltage of any one of the power converter and the motor controller when there is an error in data communication of the battery controller and control charging and discharging of the main battery based on the monitored results.