Fuel Cell Vehicle Deceleration Control via Regenerative Braking Limit
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing vehicle deceleration techniques face challenges in continuously and effectively assisting regenerative braking with mechanical brakes due to variability in regenerative electric power consumption by secondary cells, leading to complex control requirements and potential discomfort from unexpected deceleration.
Innovation Solution
The system limits regenerative braking force to the maximum consumable by auxiliary machines, allowing the mechanical brake to provide a consistent braking force, independent of secondary cell charge state, by sequentially applying different braking forces and adjusting assist duration based on vehicle speed to stabilize deceleration and prevent overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If regenerative braking force is increased to maximize energy recovery, then energy efficiency is improved, but control complexity increases due to variability in secondary cell charge state
Solution Approach 1:
The patent extracts the mechanical brake assist function from the variable regenerative braking system, creating a separate, simplified control path. By limiting regenerative braking force to a predetermined upper limit independent of secondary cell state, the system removes the complexity of continuously monitoring and responding to charge state variations while maintaining energy recovery effectiveness.
Solution Approach 2:
The system preliminarily determines an upper limit for regenerative braking force based on vehicle speed, before actual braking occurs. This predetermined limit eliminates the need for real-time adjustments based on secondary cell charge state, simplifying control while ensuring energy recovery remains within safe and effective boundaries.
2Force
If mechanical brake assists regenerative braking continuously, then braking effectiveness is improved, but risk of overheating increases
Solution Approach 1:
The patent implements periodic action by limiting the mechanical brake assist to a predetermined duration time based on vehicle speed. This time-limited assistance ensures that the mechanical brake does not operate continuously, allowing adequate cooling periods between braking events and preventing overheating while maintaining effective braking when needed.
3Loss of energy
If regenerative braking force varies with secondary cell charge state, then energy management is optimized, but deceleration stability deteriorates
Solution Approach 1:
The patent changes the control parameter from variable regenerative braking force (based on charge state) to a predetermined upper limit based on vehicle speed. This parameter change stabilizes the deceleration characteristic by making it independent of secondary cell charge state variations, while energy management is maintained through the speed-based limit structure.
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 simplifies mechanical brake control, enhances braking assist effectiveness, and maintains drivability by stabilizing vehicle deceleration and preventing unexpected fluctuations, while managing heat generation through adaptive assist duration.
Implementation Method 1
The drive motor is driven by the generated electric power of the fuel cell, and functions as an electric generator to generate regenerative electric power, depending on the vehicle running state
Implementation Method 2
A fuel cell is mounted in a vehicle, together with a motor, and receives the supply of fuel gas to generate electric power
Implementation Method 3
the mechanical brake is configured to be driven promptly in response to a brake operation for achieving an immediate and secure deceleration of the vehicle
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A vehicle includes: a fuel cell (100) that receives supply of fuel gas and generates electric power; a motor (150) that is driven by the generated electric power of the fuel cell (100); an electric power consuming auxiliary machine (135); a mechanical brake (190); a secondary cell (130), and a deceleration control unit (200). The deceleration control unit (200) limits the regenerative braking force to be obtained by the regenerative control, to an upper limit regenerative braking force corresponding to the maximum consumed electric power that the electric power consuming auxiliary machine (135) is capable of consuming such that regenerative electric power associated with regenerative braking is consumed by the electric power consuming auxiliary machine (135), and such that when the electric power consuming auxiliary machine (135) is incapable of consuming the regenerative electric power to the maximum consumed electric power, the residual regenerative electric power is consumed by charge of the secondary cell (130).