FCV Battery SOC Control for Traveling Performance
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Solution Overview
Problem
In fuel cell vehicles (FCVs) equipped with fuel cells and power storage systems, uncoordinated control of output from the fuel cells and power storage can restrict system output, leading to decreased traveling performance.
Innovation Solution
An FCV system that includes an adjustable fuel cell system output, a power storage system, and a controller that adjusts the state of charge (SOC) of the power storage to a target SOC higher than a threshold value, ensuring the power storage output does not exceed its upper limit, thereby maintaining system output and preventing performance degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If output from the FC system is controlled to adjust SOC of the power storage, then the SOC can be maintained at a target value higher than the threshold, but the system output may be restricted when SOC drops below the threshold
Solution Approach 1:
The controller proactively maintains the SOC at a target value higher than the threshold value by controlling the FC system output in advance. This preliminary action prevents the SOC from dropping below the threshold where power restriction would occur, thereby avoiding the contradiction between maintaining reliability and preserving power output.
2Reliability
If the power storage output is limited to prevent exceeding upper limit, then the power storage is protected, but the system output is restricted
Solution Approach 1:
The controller continuously monitors the SOC and adjusts the FC system output based on feedback to maintain SOC at the target value. This feedback control ensures that the power storage output remains within safe limits while maximizing system output by coordinating FC and power storage contributions.
Solution Approach 2:
The system dynamically coordinates the output between the FC system and power storage based on real-time SOC conditions. By making the power distribution dynamic rather than static, the system can protect the power storage from exceeding its output limit while maintaining high overall system output through optimal coordination.
3Power
If the target SOC is set higher than the threshold value, then restriction of system output due to lowering SOC can be avoided, but the power storage capacity is reduced
Solution Approach 1:
The controller changes the operating parameter (SOC) to be maintained at a target value higher than the threshold value. This parameter change ensures that the power storage operates in a range where it can contribute maximum output without risking restriction, thereby maintaining high system output while using the power storage capacity efficiently.
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 configuration maintains system output and prevents performance degradation by ensuring the power storage output does not exceed its upper limit, allowing the FCV to sustain traveling performance until fuel depletion.
Implementation Method 1
an FC stack that generates electric power with fuel stored in the tank
Implementation Method 2
a converter that adjusts output from the FC stack
Implementation Method 3
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. An FDC-ECU controls output from the FC system such that output from the battery does not exceed an output upper limit of the battery. The output upper limit of the battery is set to lower with lowering in SOC when the SOC becomes lower than a threshold value. A target SOC is higher than the threshold value.