Fuel Cell Capacitor Charge Threshold Adjustment for Low Temperature Restart
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Solution Overview
Problem
Fuel cell systems face difficulties in restarting at low temperatures below the freezing point due to decreased electrical energy in energy storage, especially after a short power generation period, leading to unstable operation and challenges in performing the scavenging process effectively.
Innovation Solution
A fuel cell system with a determination mechanism to identify power generation stop requests after temporary start-ups at low temperatures, adjusting the energy storage charge amount to be higher than normal stop conditions, ensuring reliable scavenging and restart capabilities by increasing the charge threshold for the energy storage when the system is stopped after start-ups at low temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the scavenging process is performed using the energy storage when power generation is stopped, then the water is removed from the membrane electrode assembly or separators, but the remaining electrical energy in the energy storage decreases, making it difficult to restart operation at low temperature
Solution Approach 1:
The system determines whether a power generation stop request is issued after temporary start-up at low temperature before actually stopping. By identifying this condition in advance, the control device can adjust the charge amount to be larger than normal, ensuring sufficient energy remains for the next scavenging process and restart operation at low temperature.
Solution Approach 2:
The charge amount for the energy storage is dynamically adjusted based on the operating conditions. When the determination mechanism identifies that the stop request occurs after temporary start-up at low temperature, the charge amount is increased beyond the normal charge threshold, adapting the energy management strategy to the specific low-temperature scenario.
2Adaptability or versatility
If operation is stopped after temporary start-up at low temperature, then the system may be restarted, but the insufficient activity of the electrolyte membrane and further decrease of remaining electrical energy make restart difficult
Solution Approach 1:
The control device performs preliminary determination of whether the stop request is issued after temporary start-up at low temperature. This early identification allows the system to proactively adjust the charge amount to be larger than normal, ensuring sufficient electrical energy remains to support the scavenging process and enable reliable restart operation at low temperature.
Solution Approach 2:
By increasing the charge amount beyond the normal threshold when low-temperature stop conditions are detected, the system creates an energy buffer or cushion in advance. This additional stored energy compensates for the energy consumption during the scavenging process and ensures sufficient power is available for the next restart, preventing system instability.
3Reliability
If the charge amount for energy storage is increased to ensure reliable scavenging at low temperature, then restart capability is improved, but the charging time increases
Solution Approach 1:
The system determines in advance whether a power generation stop request is issued after temporary start-up at low temperature. By identifying this condition before the actual stop occurs, the control device can adjust the charge amount threshold appropriately, allowing the energy storage to be charged to the required level during normal operation rather than requiring extended charging after the stop request.
Solution Approach 2:
The charge amount threshold is dynamically adjusted based on the determined operating conditions. When low-temperature stop conditions are identified, the threshold is set to a larger value; otherwise, the normal threshold is maintained. This dynamic adjustment optimizes the balance between ensuring sufficient energy for reliable restart and minimizing unnecessary charging time.
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 ensures reliable scavenging and restart of the fuel cell system at low temperatures by maintaining sufficient electrical energy in the energy storage, minimizing the time required for charging and ensuring stable operation even after temporary start-ups at freezing point temperatures.
Implementation Method 1
The catalyst of the anode induces an electrochemical reaction of the fuel gas to split the hydrogen molecule into hydrogen ions and electrons
Implementation Method 2
The electrolyte membrane is an ion exchange membrane. The hydrogen ions move toward the cathode through the suitably humidified electrolyte membrane
Implementation Method 3
an oxygen-containing gas such as the air is supplied to the oxygen-containing gas flow field, and the oxygen-containing gas flows along the cathode for inducing an electrochemical reaction
Data Source
AI summary
When it is detected that the ignition switch is turned off a short period of time after the ignition switch turned on at the temperature below the freezing point, the charge threshold of a capacitor is changed to a larger charge threshold C for increasing the amount of electrical energy charged in the capacitor based on the charge threshold C. The capacitor is used for performing a scavenging process for a sufficient period of time. At the time of starting operation of the fuel cell system at the temperature below the freezing point the next time, using the electrical energy of the capacitor, a fuel cell is warmed rapidly by a heater or the like to start operation of the fuel cell system.