燃料电池无人机混合电源系统稳定性及功率控制方法

Stability and power control method of hybrid power system for fuel cell UAVs

针对燃料电池/锂电池混合电动无人机电推进系统能源稳定性问题开展了分析。依据无人机直流微网架构确定了电推进系统带恒功率负载的稳定边界条件,并对直流微电网系统进行功率优化控制。根据燃料电池无人机典型飞行任务剖面,采用燃料电池/锂电池并联式混合电源作为电推进系统的供电单元,基于机载电推进恒功率负载的负阻抗特性,开展直流微电网系统小信号和大信号稳定性分析。利用混合势函数法得到电源系统稳定边界条件,通过增加超级电容提高系统大信号稳定域。为了优化控制系统功率响应,设计了基于规则状态机的能量管理策略,推导出系统稳定边界条件与功率优化控制之间的约束关系。搭建数字仿真模型和设计半物理实时仿真验证平台,仿真结果表明:提出的增加虚拟电阻与超级电容的控制方法,具有较好的系统稳定性和功率优化控制效果。

This paper analyzes the stability issues of the fuel cell/lithium battery hybrid electric propulsion energy sys⁃tem for UAVs.Based on the UAV’s DC microgrid architecture,the stable boundary conditions with constant power load for the electric propulsion system are determined,and power optimization control is carried out for the DC mi⁃crogrid system.According to the typical flight mission profiles of fuel cell UAVs,a fuel cell/lithium battery parallel hybrid power source is used as the power supply unit for the electric propulsion system.Based on the negative impedance characteristics of the onboard electric propulsion constant power load,small-signal and large-signal stability analyses of the DC microgrid system are conducted.The stable boundary conditions of the power supply system are obtained using the hybrid potential function method,and the system’s large signal stability domain is improved by adding super⁃capacitor.To optimize the power response of the control system,an energy management strategy based on the rulebased state machine is designed,and the constraint relationship between the stable boundary conditions and power optimization control is derived.A digital simulation model is built,and a semi-physical real-time simulation verification platform is designed.Simulation results show that the proposed control method of adding virtual resistance and super⁃capacitor has good system stability and power optimization control effects.