Fuel Cell Vehicle Controller Sub-Zero Warm-Up Strategy
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Solution Overview
Problem
Fuel cell vehicles face challenges starting at sub-zero temperatures due to frozen water in the fuel cell, leading to insufficient gas flow and reduced power generation efficiency, which can cause over-discharge of the secondary battery and potentially require an abrupt stop.
Innovation Solution
A fuel cell vehicle system that includes a temperature sensor, a detector, and a controller to manage the driving state by stopping power generation and using only the secondary battery as a power source when the fuel cell temperature is below freezing and in a low output condition for a predetermined time, limiting motor output to prevent over-discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the fuel cell operates at low efficiency to warm up the fuel cell at sub-zero temperatures, then the fuel cell temperature increases, but the output power of the fuel cell is limited and insufficient
Solution Approach 1:
The controller changes the operational parameters of the fuel cell based on temperature conditions. When the fuel cell temperature is below the freezing point, the controller switches to a warm-up operation mode with specific current and voltage parameters that prioritize heating over power output, thereby resolving the contradiction between temperature increase and power output limitation
Solution Approach 2:
The system dynamically adjusts the fuel cell's operating state based on real-time temperature feedback. The controller monitors the fuel cell temperature and dynamically switches between warm-up operation and ordinary operation modes, allowing the system to adapt its power output characteristics according to thermal conditions
2Duration of action of stationary object
If the fuel cell continues to operate with insufficient output at low temperature, then the fuel cell remains in low efficiency state, but the secondary battery becomes over-discharged
Solution Approach 1:
The controller implements feedback control by continuously monitoring both the fuel cell temperature and the secondary battery's state of charge. When the temperature is below freezing and the battery charge level drops below a predetermined threshold, the controller activates the first driving state that stops fuel cell power generation and limits motor output, thereby preventing battery over-discharge while maintaining continuous vehicle operation
Solution Approach 2:
The system prepares compensatory measures in advance by switching to an alternative power configuration before the battery becomes completely depleted. The controller predicts potential battery over-discharge scenarios and proactively activates the first driving state with limited motor output, cushioning against the harmful effect of battery over-discharge before it occurs
Data Source
AI summary
A fuel cell vehicle comprises a fuel cell, a power storage device, a drive motor, a temperature sensor configured to measure a temperature of the fuel cell, a detector configured to detect an operation condition of the fuel cell, and a controller. At a start time of the fuel cell, in a case where the temperature of the fuel cell detected by the temperature sensor is below a freezing point, when an output condition of the fuel cell shown by the detected operation condition of the fuel cell continuously corresponds to a predetermined low output condition for a predetermined reference time period or longer, the controller sets a driving state of the fuel cell vehicle to a first driving state that stops power generation of the fuel cell, drives the drive motor by using only the power storage device as a power source and limits a motor output of the drive motor to be equal to or lower than a predetermined first upper limit output.