| Integrated starter/generator system is an important development direction for unmanned aerial vehicle(UAV)power systems,and the integrated starter/generator machine is the core of the entire system,determining the performance of the system.Therefore,research on integrated starter/generator machines is of great significance.This paper introduces a new machine structure,named "strongly polymagnetic flux-switching permanent magnet(SP-FSPM)machine",by setting the "polymagnetic permanent magnet structure" at the stator slot of the conventional fluxswitching permanent magnet(FSPM)machine.The SP-FSPM has the advantages of strong magnetization ability,high power/torque density,and simple structure,and exhibits promising application prospects in the field of UAV starter/generator systems.This paper focuses on the SP-FSPM machine as the research object in the context of UAV starter/generator systems,and conducts a comprehensive study on the structure characteristics,basic principles,electromagnetic design,simulation analysis,and experimental verification of the machine.The specific work of this paper is as follows:Firstly,the research background and significance of this paper are expounded,and the advantages and disadvantages of various integrated starter/generator(ISG)machines are summarized and generalized.Based on the characteristics of the power system of unmanned aerial vehicles,the FSPM machine is chosen as the ISG machine.To address the shortcomings of conventional FSPM machines,the SP-FSPM machine is proposed and its design concept and performance advantages are presented.Additionally,the paper reveals the mechanism of the SPFSPM machine’s back electromotive force and torque generation through the principles of magnetic flux switching and magnetic field modulation.Secondly,taking into account the operational characteristics of UAVs and the performance parameters of actual engines,the performance indicators of the machine are analyzed and calculated in both starting and generating modes.Based on this analysis,the electromagnetic design of the machine is conducted,including the determination of pole slot matching,winding design,material selection,structural dimension design,research on the influence of key parameters on machine performance,and multi-objective optimization of machine structural parameters using the particle swarm algorithm.Furthermore,finite element analysis is conducted based on the machine design scheme.An electromagnetic field model is established based on the relevant theory of electromagnetic fields,and the electromagnetic performance of the machine under no-load,starting,and generating conditions is analyzed to verify that the machine meets the requirements of starting and generating performance.A temperature field model is established based on the relevant theory of heat transfer to simulate the steady-state temperature rise of the machine under generating conditions,verifying that the machine operates within the safe temperature range.The SP-FSPM machine was also compared with a conventional FSPM machine in a simulation to verify the superior performance of the SP-FSPM machine.Finally,a prototype is manufactured and an experimental platform is constructed.The machine is tested using the drag method,and the results of the no-load back electromotive force,cogging torque,and generating output are measured.The experimental results meet the design requirements and validate the feasibility of the machine design scheme. |
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