Calibrating Hydrogen Pressure Sensors Using Regulator Reference
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Solution Overview
Problem
Current hydrogen storage systems in fuel cell vehicles face inaccuracies in pressure sensor readings at low pressures, leading to premature fuel cell shutdown and reduced driving range due to high tolerance bands in high-range pressure sensors.
Innovation Solution
Calibrating all pressure sensors in the hydrogen storage system using a pressure regulator at its fully open position, reducing the tolerance band from +/-30 bar to +/-5 bar, thereby improving accuracy and extending the vehicle's driving range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If high-range pressure sensors are used to measure high hydrogen pressures in storage vessels, then the sensors can handle the high pressure range, but the accuracy at low pressure ranges deteriorates with large tolerance bands
Solution Approach 1:
The patent changes the calibration parameter of the pressure sensor by using a known reference pressure value from the pressure regulator at its fully open position. This recalibration adjusts the sensor's output to compensate for its inherent inaccuracy at low pressure ranges, effectively transforming the sensor's measurement characteristics without changing the sensor hardware itself.
Solution Approach 2:
The pressure regulator serves as an intermediary with a known, accurate pressure value that mediates between the high-range pressure sensor and the actual low pressure condition. By using the regulator's known pressure as a reference point, the system can calibrate the sensor indirectly, allowing the sensor to accurately measure low pressures despite being designed for high-range measurements.
2Reliability
If a tolerance band is applied to pressure readings to account for sensor inaccuracy, then the minimum allowable pressure can be protected, but the fuel cell must be shut down prematurely reducing driving range
Solution Approach 1:
The patent replaces the mechanical tolerance band approach with an electronic calibration solution. Instead of applying a conservative tolerance buffer that forces premature shutdown, the system uses electronic recalibration of the pressure sensor against a known reference value, thereby eliminating the need for tolerance bands and allowing the fuel cell to operate until the actual minimum pressure is reached.
Solution Approach 2:
The system performs self-calibration using its own internal components. The pressure regulator's known pressure value serves as an internal reference that allows the system to self-correct the pressure sensor's accuracy without external intervention, thereby eliminating the need for conservative tolerance bands and maximizing driving range.
3Measurement precision
If the pressure regulator is used as a reference for calibration, then the accuracy of pressure readings at low end of range improves, but the calibration can only be performed when the regulator is in fully open position
Solution Approach 1:
The system uses feedback from the pressure regulator's known pressure value to automatically recalibrate the pressure sensor. The control system monitors the regulator's state and automatically performs calibration when the regulator reaches its fully open position, eliminating the need for manual intervention and making the calibration process transparent to the operator.
Solution Approach 2:
The system performs calibration at the predetermined moment when the pressure regulator reaches its fully open position. By preparing and executing the calibration at this specific timing, the system ensures accurate low-pressure readings are established before they are needed, without requiring manual operation or interrupting normal system function.
Data Source
AI summary
A method and system for automatically calibrating all pressure sensors in a hydrogen storage system for a fuel cell vehicle. A pressure regulator in the hydrogen storage system, which has much greater accuracy at low pressures, is used to calibrate the high-range pressure sensors used in the hydrogen storage system. This calibration can only be done when the pressure regulator is in a fully open position. In such a condition, the pressure sensors can be calibrated to the regulation pressure value of the regulator, thus greatly improving the accuracy of the readings of the high-range sensors at the low end of their range. The calibration can be performed during fuel cell operation under certain circumstances, performed during a programmed shutdown sequence, or performed in a service procedure.