Fuel Cell Voltage Control for Regenerative Braking Efficiency
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Solution Overview
Problem
Existing fuel cell vehicles face inefficiencies in regenerative electric power collection and fuel cell degradation due to the need to open contactors during power generation, which affects durability and noise levels, and existing methods limit output voltage to prevent degradation but reduce system efficiency.
Innovation Solution
A fuel cell vehicle system that controls the voltage regulator to maintain a direct connection state and adjusts oxygen or hydrogen concentrations to decrease electric power output from the fuel cell, allowing regenerative electric power collection without opening the contactor, thus enhancing efficiency and preventing fuel cell degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the output voltage of the fuel cell is limited to prevent degradation (equal to or less than oxidation reduction potential), then fuel cell durability is improved, but system efficiency deteriorates because electric power generation continues even during regenerative braking when it should be collecting regenerative energy
Solution Approach 1:
The patent applies dynamics by making the fuel cell output voltage dynamically adjustable based on operating conditions. The control unit changes the output voltage according to the absolute value of regenerative torque: using a first voltage (equal to or less than oxidation reduction potential) when regenerative torque is small to prevent degradation, and a second voltage (greater than oxidation reduction potential) when regenerative torque is large to maximize energy recovery. This dynamic adjustment resolves the contradiction between durability and efficiency.
2Productivity
If the contactor is opened to disconnect the fuel cell during regenerative braking, then regenerative electric power collection efficiency is improved, but contactor durability deteriorates and noise increases due to frequent switching
Solution Approach 1:
The patent extracts the voltage regulation function from the contactor switching operation. Instead of using the contactor to disconnect the fuel cell during regenerative braking, the system uses a voltage regulator to control the fuel cell output voltage. This removes the need for frequent contactor switching, improving both regenerative energy collection efficiency and contactor durability simultaneously.
3Productivity
If the contactor is opened during power generation, then regenerative energy collection is enabled, but noise is generated and operational smoothness deteriorates
Solution Approach 1:
The patent replaces the mechanical contactor switching system with an electronic voltage control system. Instead of mechanically opening/closing the contactor to enable regenerative energy collection, the system uses electronic voltage regulation to achieve the same goal without mechanical switching noise, thereby eliminating the harmful noise factor while maintaining productivity.
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 enables efficient regenerative electric power collection without opening the contactor, improving system efficiency and preventing fuel cell degradation by optimizing power generation within a high-efficiency range.
Implementation Method 1
a fuel cell for performing power generation by inducing, by catalyst, reaction of a first gas containing oxygen and a second gas containing hydrogen supplied to the fuel cell
Implementation Method 2
inducing, by catalyst, reaction of a first gas containing oxygen and a second gas containing hydrogen
Data Source
AI summary
A fuel cell vehicle is provided. At the time of regeneration of electric power by a motor, an ECU places a DC/DC converter in a direct connection state under control, and stores electric power in a battery while decreasing oxygen concentration or hydrogen concentration by a gas supply unit to decrease electric power generated by a fuel cell.