Fuel Cell Vehicle Power Controller Temperature-Dependent Charge Limits
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Solution Overview
Problem
Fuel cell vehicles face inefficiencies in power supply before the fuel cell starts generating electricity, requiring secondary battery power and necessitating improved electric power charging efficiency to enhance fuel efficiency.
Innovation Solution
A fuel cell vehicle system with a power controller that manages the remaining charge of a power storage device, adjusting the charge limit based on temperature to optimize charging with regenerative power and reduce dependence on fuel cell charging, especially at lower temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the fuel cell system is used to charge the power storage device, then the power storage device can be charged, but the fuel efficiency deteriorates due to water discharge from fuel cell operation
Solution Approach 1:
The patent changes the control parameter from fixed remaining charge lower limit to temperature-dependent remaining charge lower limit. When temperature is low (second temperature), the lower limit is set higher, allowing more regenerative power to be stored. When temperature is high (first temperature), the lower limit is set lower, reducing the need for fuel cell charging and thus reducing water discharge and improving fuel efficiency.
2Productivity
If regenerative electric power is stored in the power storage device, then the supply efficiency of electric power is improved, but the battery health deteriorates due to excessive charging at low temperatures
Solution Approach 1:
The patent adjusts the remaining charge lower limit parameter based on temperature conditions. At low temperatures (second temperature), the lower limit is raised to prevent excessive charging that would harm battery health. At higher temperatures (first temperature), the lower limit is lowered to allow more regenerative power storage, improving supply efficiency without damaging the battery.
3Loss of energy
If the remaining charge lower limit is set low to allow more regenerative power storage, then fuel efficiency improves, but the reliability of having sufficient power for startup processing deteriorates
Solution Approach 1:
The patent implements temperature-based dynamic adjustment of the remaining charge lower limit. When temperature is low (second temperature), the lower limit is set higher to ensure sufficient power is stored for reliable startup processing. When temperature is high (first temperature), the lower limit is set lower to maximize regenerative power storage and improve fuel efficiency, as the risk of insufficient power for startup is reduced at higher temperatures.
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 approach enhances the supply efficiency of electric power for the secondary battery, improving the fuel efficiency of the fuel cell vehicle by maximizing regenerative power storage and minimizing fuel cell charging, which reduces water discharge and maintains battery health.
Implementation Method 1
a fuel cell system including a fuel cell and fuel cell auxiliary machinery
Implementation Method 2
regenerative electric power generated by traveling of the vehicle
Data Source
AI summary
In a fuel cell vehicle, when temperature of a power storage device detected by a temperature sensor is a second temperature, which is lower than a predetermined first temperature, at least in a period when the power storage device is allowed to be charged with regenerative electric power, remaining charge is controlled by setting a lower limit to a value higher than a lower limit set at the first temperature. When a stop instruction for a fuel cell system is input, remaining charge raising processing for raising the remaining charge of the power storage device is performed.