Abstract:

The durability and reliability of a proton exchange membrane fuel cell (PEMFC) stack are impacted significantly on its responses when it works under dynamic conditions. In this paper, output performances, voltage uniformities, and dynamic responses of a stack under dynamic conditions are investigated. The results show that the stack is operated well and the temperature difference between the inlet and the outlet coolants is less than 5℃. The stack voltage uniformity appears in a rush when the current has a step change. With an increase of the current, the stack voltage uniformity in the steady-state becomes worse. Under conditions of overload (200A), output differences among individual cells become large, the voltage uniformity turns worse continuously, and voltages of single cells in the middle and front of the stack decreases obviously. In addition, during the whole dynamic running process, the maximum amplitude of the voltage impulse when the current steps up are greater than those when the current steps down, but the output voltage can reach a relatively stable state within 10s (voltage fluctuation rate < 0.02). Hopefully, this work could be meaningful to those of practical operations and control optimizations of PEMFC stacks.

Key words: fuel cell, transient response, dynamic condition, voltage uniformity, steady-state

摘要：

质子交换膜燃料电池（PEMFC）电堆动态响应特性对PEMFC电堆的耐久性和可靠性具有很大影响。本文试验考察了PEMFC电堆在动态工况下的输出性能、单电池电压均衡性变化和动态响应特性。结果表明，在整个动态运行工况下，电堆运行良好，进出口冷却液温差小于5℃。电流阶跃变化时电堆电压均衡性出现突增变化，同时随着电流的增大，稳态时电堆均衡性变差。在超负荷（200A）运行工况下，电堆各单电池之间输出差异变大，均衡性持续变差，电堆中间和前端单电池电压明显降低。此外，在整个动态响应过程中电流阶跃上升时的电压最大下冲值比电流阶跃下降时的电压最大上调量大，但输出电压能在10s内达到相对稳定的状态（电压波动率＜0.02）。通过该研究，以期为实际车载电堆运行和控制优化提供参考。

关键词: 燃料电池, 瞬态响应, 动态工况, 电压均衡性, 稳态