| Proton-exchange membrane fuel cells (PEMFCs) are considered to be a new type of green energy, with advantage of no pollution, small size, low starting temperature, high efficiency and energy density. Many countries also have introduced policies to encourage and promote the application of PEMFCs, in the area of portable power supply, automotive power supply distributed power stations and so on. However, in the whole stages of fuel cell R&D, verification and manufacturing, the test system is always needed. In the stage of R&D, the test system is used to identify and optimize energy output features to improve fuel cell life and robustness. In the stage of verification, the test system is used to optimize the design to reduce costs for large-scale production. In the stage of manufacturing, the test system is used to ensure fuel cells meet the design specifications.In the R&D field of fuel cell test systems, abroad started earlier, with a lot of technology and products; while China started later, with very little technology and products. We need a set of test system with high compatibility and flexibility. It can not only meet the test requirements at this stage, while can be used to explore new test technologies, verify new test methods. On the basis of fully learning from domestic and foreign technology, this article builds a set of PEMFC test system, which is very flexible and useful. The all processes of requirements analysis, architecture, design, development and validation are given in this article. The main results of the work are as follows:1. We first point out the functional requirements of the test system, which includes accurate measurement, fast response, stable operation, recording data, security, scalability and good interface. To meet the the functional requirements, a modular system architecture is proposed. Each module of the architecture is independent and Compatible. The number of modules can be flexibly increased and decreased. According to the analysis of the technical requirement, the relevant instruments and sensors are selected. According to different signal types and communication modes of different instruments and sensors, the implementation of the system is given:select a data acquisition card with a RS485 port to acquire all analog signals; design a core control circuit board with three RS485 ports, one RS485 port, one USB port and so on to communicate with the upper computer and lower instruments.2. Based on STM32 microcontroller, we design the core control circuit, which includes the STM32 minimum circuit, the power supply circuit, the peripheral interface circuit and so on. After the work of placement, routing, proofing, welding and Debugging, we present a compact and stable Circuit board. Then, the driver code which includes two threads is written. Meanwhile, by referring to the Module Bus specification, we work out the communication protocol between the control board and the host computer,which includes two header bytes, one address byte, one function byte, eight data bytes, two sum check bytes.3. Based on LabVIEW platform, The fourth chapter designs a PC architecture, which can achieve data collection, analysis, storage and display. Then, all front panel controls and sub VIs are be written. The control logic and detailed code within the framework of each message processing loop are introduced. Finally, the design and optimization of user interface (UI) is presented.Through continuous efforts and improvements, the PEMFC test system can achieve the following indicators:100ms data update,24h continuous and stable operation,75W discharge power,200 discharge steps,256 discharge cycles,0V fuel cell unique discharge state, more than 10M of data storage capacity. The test system has been fully meet the basic needs of the laboratory tests of PEMFC. At the same time, the system with high compatibility and flexibility also has great role in promoting testing technology and control algorithms of fuel cells. |
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