Regenerative Fuel Cell Braking Control for High-SOC Vehicles
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Solution Overview
Problem
Existing vehicle systems cannot effectively recover regenerative electric power when batteries are fully charged, leading to decreased recovery efficiency of regenerative energy.
Innovation Solution
Incorporating a regenerative fuel cell with a water electrolysis device and a control system that directs regenerative power to the electrolysis device when batteries are fully charged, generating hydrogen and oxygen for fuel cell use, and using a temperature-raising device to prevent lithium deposition in lithium-ion batteries during charging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If regenerative electric power is supplied to the power storage device when SOC is high, then the power storage device can be charged, but the power storage device cannot accept more power when fully charged, leading to loss of regenerative energy
Solution Approach 1:
The system introduces a water electrolysis device as an alternative power acceptance target when the power storage device reaches full charge. This multi-functional approach allows regenerative electric power to be utilized through two pathways: charging the power storage device when SOC is low, and electrolyzing water to produce hydrogen and oxygen when SOC is high, thereby eliminating energy loss regardless of battery state
2Loss of energy
If regenerative electric power is supplied to the water electrolysis device when SOC is high, then regenerative energy can be recovered as fuel, but the system complexity increases
Solution Approach 1:
The water electrolysis device enables the system to serve itself by converting excess regenerative electric power into chemical energy (hydrogen and oxygen fuels) that can be stored and utilized later. This self-service mechanism allows the system to handle its own energy surplus without external intervention or complex grid integration, simply by adding the electrolysis component and control logic
3Productivity
If charging current is increased to improve charging speed, then productivity increases, but lithium deposition occurs in lithium-ion batteries
Solution Approach 1:
The control device continuously monitors the SOC of the power storage device and dynamically adjusts the charging current based on real-time battery state. When SOC approaches the upper limit, the control device automatically reduces or stops charging current to the power storage device and redirects regenerative power to the water electrolysis device, preventing lithium deposition while maximizing charging efficiency during appropriate SOC ranges
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
Enables the recovery of regenerative electric power even when batteries are fully charged, improving energy recovery efficiency by preventing lithium deposition and optimizing charging currents based on temperature and state of charge.
Implementation Method 1
a motor generator (MG) configured to generate regenerative electric power when the vehicle brakes
Implementation Method 2
the water electrolysis device can generate oxygen and hydrogen by electrolyzing water using the supplied regenerative electric power
Implementation Method 3
a regenerative fuel cell (RFC) including a water electrolysis device (72) and a fuel cell (71)
Data Source
AI summary
A vehicle includes: a power storage device; a regenerative fuel cell including a water electrolysis device and a fuel cell; a motor generator configured to be driven using electric power of at least one of the power storage device and the fuel cell; a driving wheel configured to be driven by the motor generator; and a control device configured to perform regeneration control of generating regenerative electric power by the motor generator at a time of braking of the vehicle. The control device is configured to supply the regenerative electric power to the water electrolysis device when an SOC of the power storage device is equal to or greater than a predetermined value at a time of performing the regeneration control.