Fuel Cell Vehicle Cold Start Controller
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Solution Overview
Problem
Fuel cell vehicles face challenges in rapid startability during cold starts due to current sensing errors, which can lead to inadequate heating and potential battery durability issues from overcharging or undercharging.
Innovation Solution
A method for controlling the start of a fuel cell vehicle involves adjusting the charge limit current based on sensed and actual charge currents, with a controller managing the air supply and converter operations to maintain optimal current output and prevent overcharging or undercharging, ensuring maximum heating and efficient battery charging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the charge current is set high to maximize heating during cold start, then the fuel cell heating efficiency is improved, but the battery may be overcharged due to current sensing errors
Solution Approach 1:
The patent implements a feedback control mechanism where the controller continuously monitors the actual charge current and compares it with the charge limit current. Based on this comparison, the controller dynamically adjusts the charge limit current to prevent battery overcharging while maximizing heating during cold start. This closed-loop feedback system resolves the contradiction by enabling high current operation when accurate and compensating for sensing errors through real-time monitoring and adjustment.
2Reliability
If the charge current is set low to prevent battery overcharging, then the battery durability is improved, but the fuel cell heating efficiency is reduced
Solution Approach 1:
The patent employs dynamic adjustment of the charge limit current based on real-time operating conditions. Rather than using a fixed conservative current limit, the system dynamically optimizes the charge current within safe boundaries by continuously monitoring actual current delivery. This dynamic approach allows the system to operate at higher currents when conditions permit (maximizing heating) while automatically reducing current when sensing errors or battery state indicate potential overcharging risks, thus resolving the contradiction between heating efficiency and battery durability.
3Measurement precision
If the charge limit current is dynamically adjusted based on actual charge current sensing, then the accuracy of charge control is improved, but the complexity of the control system increases
Solution Approach 1:
The patent uses feedback control to continuously monitor the actual charge current and adjust the charge limit current accordingly. This feedback mechanism improves measurement precision by compensating for sensing errors through real-time comparison and adjustment. The added complexity is minimal, involving only the comparison logic and adjustment algorithm in the controller, which is a standard function in modern battery management systems.
4Temperature
If the voltage of the high voltage bus is maintained at the lowest control voltage during cold start, then the fuel cell current output is maximized for rapid heating, but the risk of battery overcharging increases due to sensing errors
Solution Approach 1:
The patent implements feedback control that monitors the actual charge current delivered to the battery and uses this information to adjust the charge limit current. This allows the system to maintain low bus voltage for maximum heating while compensating for sensing errors through real-time feedback. The controller dynamically adapts the charge limit based on the discrepancy between commanded and actual current, preventing overcharging even during aggressive cold start heating modes.
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 maximizes current output from the fuel cell during cold starts, enhancing startability and preventing battery degradation by dynamically adjusting the charge limit current to match the actual charge needs, thereby optimizing heating and battery health.
Implementation Method 1
providing, by a controller, hydrogen and air to a fuel cell... an output stage of the fuel cell may be connected
Implementation Method 2
operating, by the controller, a converter to maintain a voltage of a high voltage bus constant, wherein the converter may be disposed between a high-voltage battery and the high voltage bus
Implementation Method 3
driving of a fuel cell with a low voltage and a high current during a cold start is advantageous in that a fuel cell is heated
Data Source
AI summary
A system and method for controlling a start of a fuel cell vehicle are provided. The method includes providing hydrogen and air to a fuel cell and operating a converter to maintain a voltage of a high voltage bus constant. The converter is disposed between a high-voltage battery and the high voltage bus to which an output stage of the fuel cell is connected, and the voltage of the high voltage bus becomes a preset lowest control voltage. A charge current of the high-voltage battery is set as a charge limit current and an air supply amount is adjusted and the converter is operated to provide a current corresponding to an amplitude of the charge limit current to the high-voltage battery. The charge limit current is changed based on comparing a sensed charge current, obtained by sensing a current input to the high-voltage battery, with the charge limit current.