燃料电池-锂电池混合供电系统的无源控制策略及参数设计方法

Passivity-Based Control Strategy and Parameter Design Method for Fuel Cell-Lithium Battery Hybrid Power Supply System

多源混合供电技术可有效地利用不同供电单元性能,在电气化交通系统中得到广泛应用。然而,随着越来越多的恒功率特性及强脉动特性负载接入供电系统,系统的稳定性难以得到保证。针对传统线性控制方法难以保证系统的大信号稳定性,而现有非线性控制的研究仍缺乏兼顾稳定性和动态性能的控制参数设计方法的问题,该文对燃料电池-锂电池混合供电系统设计基于无源控制和扩张高增益状态观测器的复合控制方法,并对控制器和观测器参数进行了设计,有效地保证了系统的动静态性能。在实验室搭建一套额定功率为3 kW的燃料电池-锂电池混合供电系统实验平台进行测试,结果验证了所提控制策略和参数设计方法的有效性和正确性。

Multi-source hybrid power supply technology can effectively utilize the performance of different power supply units and is widely used in electrified transportation systems.However,as more and more loads with constant power characteristics and strong pulsation characteristics are connected to the system,the system's large-signal stability and dynamic performance are hard to guarantee.Recently,some nonlinear control methods were presented to enhance the stability and dynamic performance of the power supply.However,most existing studies have yet to consider the parameter design that takes into account the dynamic performance and stability of the system.Therefore,this paper designs a composite control method based on passivity-based control(PBC)and extended high-gain state observer(EHGSO)for the fuel cell(FC)-lithium battery(LB)hybrid power supply system(HPSS).The detailed design of the controller and observer parameters is provided,effectively ensuring the system's dynamic and static performance.First,a mathematical model of the Boost converter considering parameter uncertainty is established.The proposed mixed droop controller is employed and designed for decentralized power allocation.Then the PBC was designed,and its stability was strictly proved based on the Lyapunov stability theory.Due to parameter uncertainties,an EHGSO was employed to enhance the system’s ability to cancel uncertainties.A general system parameter tuning method,which considers the converter's static and dynamic requirements,is finally proposed based on the small-signal analysis method.The simulation model and experimental platform are designed and established.Simulation and experimental results verify the composite controller and the proposed parameter design method.Specifically,the simulation results show that the dynamic response of the FC converter increases with the increase of virtual dissipation resistance and decreases with the rise of virtual dissipation conductance(both of which are adjustable parameters of the PBC controller).The rising time and overshoot are approximately 20 ms and 2%for the FC converter,6 ms and 1%for the LB converter,and 10 ms and 4%for the EHGSO,respectively.In addition,the experimental results of the FC/LB HPSS with step-changing constant power load(CPL)show that when the CPL steps up from 0.3 kW(10%of full load)to 3 kW(full load),the FC unit responds slowly to load power changes and eventually provides all the load power.In contrast,the LB unit reacts quickly to sudden load power changes with a steady-state output power of 0 kW.In the process,the bus voltage is stable and smooth in the presence of the EHGSO.Similarly,in the case of pulsation load,the LB and FC units automatically supply power to high-and low-frequency loads,respectively.The output power of the FC unit is smoother with EHGSO.In summary,the following conclusions can be made:(1)The composite controller,composed of a PBC and an EHGSO,can allocate the load power to the FC and LB units in a decentralized way;(2)The small-signal modeling and analysis method can be employed to design the parameters of nonlinear controllers to satisfy the system’s dynamic requirements.(3)The proposed parameter design method can be used as a general guideline for designing system parameters of HPSS when nonlinear controllers are adopted.