COD Heater Control for Fuel Cell Regenerative Braking
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Solution Overview
Problem
The existing fuel cell systems face inefficiencies in regenerative braking due to constant power consumption by the cathode oxygen depletion (COD) heater, leading to unnecessary discharge of the high voltage battery and reduced driving efficiency, especially when the charge amount is below a predetermined level.
Innovation Solution
A COD control method and system that compares power generation and power consumption to adjust the operation of the COD heater, coolant pump, and heat dissipation fan, optimizing their rotation speeds and voltage to match the difference between generated and consumed power, thereby minimizing unnecessary power usage and battery discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the COD heater is operated at constant power during regenerative braking, then the stack durability is protected and cold startability is ensured, but the high voltage battery discharges unnecessarily and driving efficiency decreases
Solution Approach 1:
The COD heater's power consumption is changed from constant to dynamic adjustment. The controller varies the COD heater's power consumption based on the difference between power generation and power consumption, allowing the system to adapt to changing operating conditions during regenerative braking and maintain battery charge when possible.
Solution Approach 2:
The power consumption parameter of the COD heater is adjusted dynamically. By changing the power consumption parameter from a fixed value to a variable value determined by the controller, the system can optimize energy usage while still protecting the stack and ensuring cold startability.
2Reliability
If the COD heater operates at constant power, then the stack is protected from degradation, but the charge amount of the high voltage battery decreases below predetermined level
Solution Approach 1:
The controller continuously monitors the difference between power generation and power consumption, as well as the battery charge amount, and uses this feedback information to adjust the COD heater's power consumption. This closed-loop control ensures that the stack is protected while preventing unnecessary battery discharge.
3Productivity
If auxiliary machinery operates at maximum power consumption, then power is maximally consumed during regenerative braking, but the high voltage battery discharges when COD consumption output exceeds dump power
Solution Approach 1:
The power consumption of auxiliary machinery is changed from maximum fixed operation to dynamic adjustment. The controller adjusts the rotation speeds of the coolant pump and heat dissipation fan based on the power balance, allowing the system to maximize power consumption when possible while preventing battery discharge when COD consumption output exceeds dump power.
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 prevents wastage of charged power, improves driving efficiency, reduces noise and wear on auxiliary machinery, and extends the durability of the high voltage battery by optimizing power consumption during regenerative braking.
Implementation Method 1
a fuel cell stack configured to generate electric energy from an electrochemical reaction of reaction gases
Implementation Method 2
a heater, which is capable of rapidly heating the coolant to help the stack generate power at a temperature below the freezing point smoothly after the start of the vehicle
Implementation Method 3
a pump that pumps the coolant through the coolant line
Implementation Method 4
a radiator for circulation of a coolant
Implementation Method 5
a radiator for circulation of a coolant
Data Source
AI summary
A cathode oxygen depletion (COD) control method is provided. The method includes determining whether a COD heater operates and calculating power generation and power consumption when the COD heater operates. Additionally, the power consumption is adjusted by comparing the calculated power generation and power consumption.