質子交換膜燃料電池控制及整合

Abstract

本論文利用系統識別方法求得質子交換膜燃料電池系統之數學模型，並應用強韌控制理論進行控制器設計及安裝，以達到穩定輸出電壓以及降低氫氣消耗的目標。 為簡化燃料電池本身的複雜架構，吾人由系統的觀點出發，將燃料電池系統視為一雙輸入雙輸出的系統，其輸入為空氣與氫氣的流量，輸出為電壓與電流，若是固定輸出負載，則該系統可進一步簡化為雙輸入單輸出之系統，因此吾人可藉由控制空氣與氫氣的流量，來控制電壓或電流的輸出量。再者，由於燃料電池本身為非線性且時變的系統，於是本文利用系統識別方法，在各操作點將質子交換膜燃料電池識別為雙輸入單輸出之線性系統，並將系統之非模型化動態，視為系統不確定性與外部干擾，利用強韌控制來達到穩定系統與增進效能的目標。 因為一般電器用品或是直流電壓轉換器皆需要穩定的電壓供應，所以在本文中以穩定輸出電壓為首要目標；另外，本文也針對一般的強韌控制具有階數較高（系統階數加上權重函數的階數）的缺點，引入定階強韌控制理論以及強韌PID設計方法，希望以較低階的控制器達到預期的控制目標。

This thesis proposes control and integration of a proton exchange membrane fuel cell (PEMFC) system. At first, we assemble a PEMFC system, and find the system characteristics by identification techniques. Finally, we apply various robust control strategies to stabilize output voltage and to increase performance and efficiency of the PEMFC system. From the system point of view, PEMFC can be regarded as a two-input-two-output system with the inputs of hydrogen and oxygen, and the outputs of cell voltage and current. By fixing the output resistance, the system can be further reduced to a two-input-single-output system. That is, we can either control the cell voltage or current output by regulating the air and hydrogen flow rates. By identification techniques, we find linear models of the PEMFC system at different operating points. And all unmodelled dynamics were considered system uncertainties. Then, we apply robust control strategies to stabilize the system and to increase the system performance. Because steady power supply is critical for electrical machinery, we aim to maintain steady output voltage. At first, we apply standard robust control design to stabilize the PEMFC system. However, the order of resulting controllers is constrained by the plants and weighting functions. Therefore, we apply fixed-order robust control and robust PID control algorithms to design controllers for a PEMFC. Finally, we evaluate efficiency of the system employing these controllers.