## 4 Results and Discussions
### Sensitivity Analysis  
The impact of operational parameters on the total power consumption of the air compressor in hydrogen energy vehicles is illustrated in Figure 4. Based on the results, the rotational speed exhibits the highest sensitivity to total power consumption. In contrast, the pressure ratio and intake air temperature demonstrate a comparable level of sensitivity to total power consumption. It is noteworthy that the impact of rotational speed on total power consumption significantly surpasses that of the pressure ratio and intake air temperature. This is because the total power consumption is primarily determined by the permanent magnet synchronous motor, and the rotational speed represents the most influential factor affecting the energy consumption of the motor. Therefore, to reduce the power usage of the air compressor and enhance the energy efficiency of HFCVs, efforts should be made to operate the air compressor at lower rotational speeds whenever possible.  
The sensitivity analysis results of operational parameters on the efficiency under isentropic conditions in a dual-stage centrifugal air compressor are depicted in Figure 5. Among these factors, the pressure ratio exhibits the most pronounced sensitivity to the isentropic efficiency, followed by rotational speed, while the intake air temperature has the least impact. This is because the pressure ratio directly influences the adiabatic compression work of the centrifugal air compressor. Moreover, the pressure ratio should be prioritized for adjustment as the primary factor when targeting high isentropic efficiency. In comparison to the influence of the pressure ratio and rotational speed on isentropic efficiency, the impact of the inlet temperature is minimal.  
The sensitivity analysis of operational parameters on the corrected mass flow rate of the air compressor in hydrogen energy vehicles is illustrated in Figure 6. The research findings indicate that the pressure ratio has the most significant impact on the mass flow rate of the air compressor, followed closely by the rotational speed, and the influence of inlet temperature on the flow rate is minimal. Therefore, the primary adjustment should focus on modifying the pressure ratio of the compressor when hydrogen-powered vehicles require higher mass flow rates from the air compressor to the stack. Furthermore, simultaneous adjustments, including the pressure ratio and the rotational speed of the air compressor, could be considered to meet the larger flow rate requirements of the fuel cell stack.  
Figure 4: The sensitivity of operational parameters to total power consumption.  
Figure 5: The sensitivity of operational parameters to isentropic efficiency.  
Based on the above results and discussions, it is evident that the Morris global sensitivity analysis accurately identifies the impact magnitude of operational parameters on the objective variables. When hydrogen energy vehicles exhibit varying demands on the air compressor, the Morris sensitivity analysis results effectively guide the efficient operation of the air compressor to meet the specific requirements of the fuel cell stack. However, further discussion and research are required to investigate the effects of operational parameters on the optimization objectives of the air compressor.