Dynamic Low-Voltage Battery Charging Control for Fuel Cell Vehicles
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Continuous charging of low-voltage batteries in fuel cell vehicles with a fixed voltage can lead to excess current and thermal loss due to high state of charge, reducing fuel efficiency.
Innovation Solution
A method and apparatus that dynamically adjust the charge voltages of a low-voltage battery based on various vehicle drive modes and high-voltage battery charge states, using a controller to set preset voltages and adjust charge currents, preventing overcharging and optimizing energy use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed voltage of about 14 V is used to charge the low-voltage battery, then the battery charging is simple and stable, but excess charge current occurs when the state of charge is high, causing overheat and thermal loss
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed charge voltage to a variable charge voltage that adapts to the battery's state of charge. The controller dynamically adjusts the charge voltage based on real-time battery conditions, implementing a multi-stage charging strategy where the voltage is reduced when the battery reaches high charge levels, thereby preventing excess current and thermal loss while maintaining charging stability.
Solution Approach 2:
The patent applies parameter changes by modifying the charge voltage parameter based on the battery's state of charge. Instead of maintaining a constant 14 V, the system changes the voltage parameter dynamically - using higher voltages when the battery is discharged and reducing the voltage when the battery approaches full charge. This parameter adaptation resolves the contradiction by optimizing both charging efficiency and thermal management.
2Reliability
If continuous charging is applied to the low-voltage battery, then the battery maintains sufficient charge, but fuel efficiency deteriorates due to excess current and thermal loss
Solution Approach 1:
The patent applies periodic action by implementing an intermittent charging strategy rather than continuous charging. The controller periodically monitors the battery's state of charge and adjusts the charging operation accordingly - activating charging when the battery needs power and pausing or reducing charging when the battery is sufficiently charged. This periodic control ensures battery availability while minimizing unnecessary energy consumption that would reduce fuel efficiency.
Solution Approach 2:
The patent applies partial action by providing charging only when necessary rather than continuous full charging. The system determines the optimal charging level based on vehicle operation modes and battery state, applying partial charging during certain conditions (such as when the vehicle is stationary or during specific drive modes) and avoiding charging during others. This partial charging approach maintains sufficient battery charge while reducing overall energy consumption and improving fuel efficiency.
3Productivity
If the charge voltage is increased to improve charging speed, then the charging efficiency improves, but thermal loss and overheat risk increase
Solution Approach 1:
The patent applies dynamics by making the charge voltage adaptive rather than static. The controller continuously monitors battery conditions and dynamically adjusts the charge voltage to optimize the balance between charging speed and thermal management. When the battery can accept high current, the voltage is increased to improve charging speed; when thermal conditions deteriorate or the battery approaches full charge, the voltage is reduced to control temperature, thereby resolving the contradiction between charging productivity and temperature control.
Data Source
AI summary
A method and apparatus for controlling charge of a low-voltage battery are provided. The method includes assigning, by a controller, a preset voltage for the low-voltage battery based on an operating mode of a vehicle and a charge state of a high-voltage battery. In addition, the controller compares the preset voltage with a present charge voltage of the low-voltage battery and increases the present charge voltage with a first slope until the present charge voltage becomes equal to the preset voltage when the preset voltage is greater than the present charge voltage. The operating mode comprises drive modes that include a first drive mode and a second drive mode, a fuel cell stop mode, and an emergency mode. The first drive mode is divided into a plurality of stages based on the charge state of the high-voltage battery.