Design Of Hydrogen Detection Device For Low-concentration And Constant Temperature Difference Of FCX Clarity

With the increasing prominence of global energy problems,hydrogen fuel cell vehicles have gradually become research and development hotspots in the field of electric vehicles because of their advantages of zero pollution,zero emissions and fuel renewable.However,the flammable and explosive characteristics of hydrogen fuel have brought great challenges to its development and popularization.The internal water vapor concentration of hydrogen fuel cell vehicle is high,the temperature changes greatly,and the hydrogen concentration is low.The existing hydrogen detection device is difficult to detect hydrogen accurately and reliably in this environment.Therefore,it is of great significance to design a high precision hydrogen detection device used in hydrogen fuel cell vehicle.In this paper,the working principle of catalytic combustion sensor and the mechanism of hydrogen catalytic reaction are studied,and it is proved that hydrogen can react violently at-50?.The catalytic combustion sensor was selected as the hydrogen detection sensor,the sensitivity of the catalytic sensor to low concentration hydrogen was tested at room temperature,and the overall design scheme based on the constant temperature difference double bridge detection circuit was put forward.The sensitivity of the sensor is measured under different working current,and the working current with low power consumption and constant temperature difference is determined.The relationship between the parameters of constant thermoelectric bridge and the temperature difference is calculated,When the sensor is controlled at 50 ? above the ambient temperature,the influence of high concentration steam can be reduced.The heat dissipation process of the sensor is analyzed by using the unstable heat conduction theory,and the cooling time of the sensor is calculated,which makes the sensor work intermittent,realizes low power consumption and reduces the influence of condensation at the same time.On this basis,the hardware circuit of the detection device and the software program of the single chip microcomputer are designed in this paper.The hardware circuit includes the PIC18F458 single chip microcomputer and its peripheral auxiliary circuit,the detection circuit,the power supply circuit and the CAN bus circuit.The software program includes the main program,the detection program,the calibration program,the CAN bus and other peripheral programs.According to the design index and the design scheme of software and hardware,six test prototypes were made.After 45 days of aging,the stability of the prototype at room temperature and high and low temperature was tested by using high humidity hydrogen of 0.50 ?4.00%,The accuracy and reliability of CAN bus data transmission are verified by USB can II analyzer.The experimental results show that the hydrogen detection device with low concentration and constant temperature difference of the hydrogen fuel cell vehicle has good detection performance at room temperature and high and low temperature with high humidity,and can bus data transmission is accurate and reliable,which conforms to the design standards at home and abroad,and has broad application prospects.