Fuel Cell Cold Start Voltage Control to Prevent Battery Overcharge
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
During cold starts of fuel cell vehicles, the fuel cell controller's output commands do not reflect the current vehicle state, leading to potential overcharging of the high-voltage battery and concerns about durability.
Innovation Solution
A cold start system and method that calculates an available power output for the fuel cell vehicle, determines an output voltage for the fuel cell stack based on this available power, and adjusts this voltage by adding a voltage offset calculated from the cell voltage ratio and state of health of the fuel cell stack.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the fuel cell controller transmits output commands to the DC-DC boost converter during cold start, then heat generation for the fuel cell stack is improved, but the high-voltage battery may be overcharged causing durability concerns
Solution Approach 1:
The patent implements dynamic control of the output voltage command during cold start by adjusting it based on the charge state of the high-voltage battery. The controller modifies the voltage command in real-time according to battery SOC (state of charge) levels, ensuring that heat generation requirements are met while preventing overcharging conditions that would compromise battery durability.
Solution Approach 2:
The system incorporates feedback control by continuously monitoring the charge state of the high-voltage battery and using this information to adjust the output voltage command from the fuel cell stack. This closed-loop control ensures that the cold start process generates sufficient heat while simultaneously protecting the battery from overcharging, resolving the contradiction between temperature increase and battery reliability.
2Ease of operation
If a fixed output voltage command is used during cold start, then control simplicity is maintained, but the system cannot adapt to varying vehicle states and fuel cell stack performance
Solution Approach 1:
The patent transitions from fixed to dynamic voltage command control during cold start. The output voltage command is continuously adjusted based on real-time vehicle state information and fuel cell stack performance parameters, enabling the system to adapt to varying conditions while maintaining manageable control complexity through structured control logic.
Solution Approach 2:
The system changes the voltage command parameter dynamically during cold start based on monitored vehicle state and stack performance. By modifying the voltage command according to actual operating conditions, the system achieves adaptability without requiring complex control structures, as the adjustments follow predefined relationships with measurable parameters.
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 allows for variable control of the output voltage of the fuel cell stack, reflecting the vehicle's state and the fuel cell stack's performance, thereby preventing overcharging and maximizing the likelihood of successful cold starts.
Implementation Method 1
A fuel cell is a device that receives hydrogen and air from an outside and generates electrical energy through an electrochemical reaction inside a fuel cell stack
Implementation Method 2
The cold start utilizes loads such as a heating element (COD), air compressor (ACP), and high-voltage battery within the fuel cell system to raise the temperature of the fuel cell stack
Data Source
AI summary
A cold start system of a fuel cell vehicle can include an auxiliary component of a fuel cell vehicle, a fuel cell stack, and a controller that calculates an output voltage of the fuel cell stack based on an available output of the fuel cell vehicle, calculates a voltage offset based on a general performance of the fuel cell stack, and calculates a final voltage by adding up the calculated output voltage and voltage offset of the fuel cell stack.