Design And Implementation Of Online Detection System Of Single Fuel Cell Resistance

Proton exchange membrane fuel cell(PEMFC), which is clean, green and high energy efficient, is considered the best replacement of traditional internal combustion engine. Resistance is an important parameter and response to fuel cell running conditions. So it's very important to monitor the resistance of PEMFC. The current resistance testing systems can only run offline. To meet the online needs, this thesis designed a high-precision PEMFC resistance online detecting system. Main contents are as follows:(1) Described the working principles of fuel cells, analyzed the characteristics of the PEMFC test model and the equivalent circuit. After comparing the domestic and international research methods of fuel cell resistance, the thesis proposed a new testing method based on EIS.(2) Designed the hardware of bottom control unit and high-precision sampling processing unit of the system. For the former, the design details contain MCU minimum system circuit, fiber CAN interface circuit, pair-twisted CAN interface circuit,485 communication interface circuit; For the later, the design details contain data acquisition circuit, DC signal processing circuit, A/D converter circuit and AC signal processing circuit. The AC signal processing circuit includes narrowband frequency conversion filter, programmable gain amplifiers, root-mean-square detector and amplitude phase detector.(3) Designed the software of bottom control unit and high-precision sampling processing unit. Specifically, the thesis divided the software modules according to the function. The whole software design includes initialization program, narrowband frequency conversion filters setup filter program, AD converter program, SPI communication program and interrupt program. At last, the thesis made up a communication protocol.At last, the thesis did some experiments about the whole system and narrowband frequency conversion filter. The experiments showed the high precision characteristics of the system and proved the system's ability to meet the real-time online detection of single REMEC's resistance.