Fraunhofer Institute for Physical Measurement Techniques IPMMiniaturized H2 sensor system to ensure acceptance of fuel cell drive systems
In the future, fuel cells (FCs) will increasingly be used in high-performance commercial vehicles (medium to large loads, above around 110 kW). In the FC, hydrogen is converted into electrical energy and drives an electric motor. Powered by green hydrogen (H2), hydrogen-based fuel cell electric drives are a highly efficient, virtually emission-free alternative to combustion engines. However, the use of hydrogen carries the risk of ignition or even explosion. Sensor systems for detecting H2 leaks are therefore a prerequisite for the widespread acceptance and use of hydrogen-based FC drives in vehicles. The high safety standards of the automotive industry can only be met with reliable H2 sensor systems. As part of the HySABi project, Fraunhofer IPM has developed a new type of H2 sensor system for hydrogen-powered commercial vehicles together with partners from industry
Functional safety by combining two measurement methods
In order to guarantee the high safety standards of the automotive industry, an H2 sensor system based on two independent measuring principles for detecting hydrogen was developed as part of the HySABi project: A thermal conductivity detector (WLD) and a catalytic heat tint sensor (pellistor) were combined to form a compact sensor system and constructed as a functional demonstrator using MEMS technology. The sensor system measures 78 mm × 30 mm × 15 mm which means it is no bigger than a USB stick.
In addition to the H2 sensors, a humidity and a temperature sensor are also integrated on the circuit board. The characterization of the WLD and pellistor revealed a significant influence of temperature, humidity and pressure on the measured values. Compensation of these influences is therefore necessary to ensure the functional reliability of the sensor system. More detailed investigations of the pellistor with regard to the environmental influences of temperature, humidity and pressure fluctuations are still pending.
The functional demonstrator was successfully tested on a high-pressure hydrogen test bench. The WLD and pellistor detected H2 leaks on a supply line at the same point in time with the same signal strength.
