Fuel Cell Vehicle Charging Control for Low-SOC Startup Output
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Solution Overview
Problem
Fuel cell vehicles (FCVs) experience reduced traveling performance after startup due to low state of charge (SOC) of the power storage system, leading to restricted system output when external charging is not performed during system stop.
Innovation Solution
The FCV system includes a controller that initiates FC charging when the SOC falls below a threshold, ensuring a higher SOC at startup, and can switch to external charging when available, or prioritize FC charging if external charging is not performed within a prescribed time or if electricity fees are high.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If external charging is not performed during system stop, then the vehicle can be used flexibly without charging facilities, but the SOC becomes low at startup causing restricted system output and lowered traveling performance
Solution Approach 1:
The system performs preliminary FC charging during system stop when SOC is low, proactively replenishing power storage before the next startup. This preliminary action ensures high SOC at startup, preventing output restrictions and maintaining traveling performance without requiring external charging facilities.
2Productivity
If FC charging is carried out to maintain high SOC, then traveling performance is maintained, but fuel consumption increases
Solution Approach 1:
The system dynamically adjusts the output upper limit of the power storage based on real-time SOC levels. When SOC is low, the output upper limit is reduced to prevent excessive FC charging and fuel consumption. When SOC is high, the output upper limit is increased to utilize stored energy, thereby optimizing the balance between traveling performance and fuel consumption.
Solution Approach 2:
The controller changes the output upper limit parameter of the power storage according to SOC threshold values. By adjusting this parameter dynamically, the system optimizes the balance between maintaining traveling performance and preventing excessive fuel consumption during FC charging operations.
3Power
If the output upper limit of power storage is set high, then traveling performance is improved, but when SOC is low, the system output becomes restricted
Solution Approach 1:
The controller dynamically changes the output upper limit parameter of the power storage based on SOC levels relative to threshold values. When SOC is high, the output upper limit is set high to maximize traveling performance. When SOC drops below the threshold, the output upper limit is reduced to prevent output restriction, thereby maintaining reliable system output availability.
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 maintains high SOC levels at startup, preventing output restrictions and minimizing fuel depletion, thus enhancing traveling performance and reducing energy costs.
Implementation Method 1
an FC system 20 including an FC stack 22
Implementation Method 2
a battery 40; a power storage, a driving device that receives electric power from at least one of the FC system and the power storage
Data Source
AI summary
An FCV includes an FC system and a battery. The FC system includes an FC stack and a boost converter that adjusts output from the FC stack. When a prescribed operation to carry out external charging with a power supply outside the vehicle is not performed for a prescribed time period after system stop (Ready-off) of the FCV under such a condition that an SOC of the battery is lower than a threshold value at the time of system stop, an FDC-ECU controls the boost converter to carry out FC charging by the FC system.