Fuel Cell Power Control System for Battery Overcharge Prevention
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Solution Overview
Problem
In fuel cell vehicles, direct connection of fuel cells and batteries can lead to battery overcharging and accelerated catalyst deterioration during start-up and shut-down processes, as existing solutions either stop power generation or disconnect fuel cells without effectively managing battery charge levels.
Innovation Solution
A vehicle electric power supply control system that includes a battery charge level determining module, a switch unit, and a controller to disconnect fuel cells from the battery and motor when the battery charge level exceeds a threshold, and manage power generation to prevent overcharging and reduce start-up/shut-down frequency, using a field effect transistor as the switch unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fuel cells are directly connected to battery without DC/DC converter, then device complexity is reduced, but battery overcharging risk increases
Solution Approach 1:
The patent introduces a control unit as an intermediary between the fuel cell and battery system. This control unit monitors battery charge levels and manages power flow, replacing the need for a DC/DC converter while preventing battery overcharging through intelligent control rather than passive electrical isolation.
Solution Approach 2:
The control unit dynamically adjusts operational parameters based on battery charge state. When battery charge reaches predetermined thresholds, the control unit modifies power distribution parameters to prevent overcharging, enabling direct connection safety through active parameter management rather than fixed electrical architecture.
2Reliability
If fuel cells are disconnected from battery when charge level is high, then battery overcharging is prevented, but fuel cell catalyst deterioration accelerates due to voltage open-circuit state
Solution Approach 1:
The control unit implements dynamic threshold management with hysteresis. Instead of a single static disconnect threshold, the system uses multiple charge level thresholds and maintains fuel cell connection in intermediate states, dynamically adjusting operational mode based on real-time battery charge conditions to prevent both overcharging and catalyst deterioration.
Solution Approach 2:
The control unit employs periodic monitoring and controlled power cycling. Rather than simple on/off disconnection, the system periodically assesses battery charge levels and implements controlled power flow adjustments, maintaining fuel cell operation in a managed manner that prevents prolonged open-circuit voltage exposure while preventing battery overcharge.
3Productivity
If fuel cells continue power generation when battery is fully charged, then productivity is maintained, but battery overcharging occurs
Solution Approach 1:
The control unit implements continuous feedback monitoring of battery charge levels. When the battery reaches a predetermined charge threshold, the control unit receives feedback signals and automatically adjusts power distribution, diverting excess power away from the battery while maintaining fuel cell operation, thus preserving productivity while preventing overcharging through closed-loop control.
Solution Approach 2:
The control unit serves multiple functions simultaneously: it monitors battery charge levels, manages power flow distribution, prevents overcharging, and maintains optimal fuel cell operation. This multi-functional control approach enables the system to maintain productivity across varying battery states without requiring separate control systems for each function.
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
Prevents battery overcharging, reduces fuel cell deterioration by controlling power generation based on battery charge levels, and prevents overcurrent issues through controlled connection and disconnection, thereby extending the lifespan of both battery and fuel cell components.
Implementation Method 1
fuel cells for generating electric power to provide the generated electric power to the motor and the battery
Implementation Method 2
battery for storing electric power to provide the stored electric power to the motor
Data Source
AI summary
To restrain deterioration of fuel cells while preventing a battery from being overcharged, a fuel cell vehicle includes a motor for providing torque to wheels, a battery for storing electric power to provide the stored electric power to the motor, and a FC stack for generating electric power to provide the generated electric power to the motor and the battery. A battery charge level determining module determines a battery charge level of the battery, and a FET is configured to connect or disconnect the FC stack to the motor and the battery. A controller is configured to cause the FET to disconnect the FC stack from the motor and the battery and allow power generation by the FC stack when the determined battery charge level by the battery charge level determining module is greater than or equal to a first predetermined threshold.