Novel Axial-Field Dual-Rotor Segmented Switched Reluctance Machine

In order to improve the power/torque density and reduce the iron loss,a novel axial-field dual-rotor segmented switched reluctance machine(ADS-SRM)is developed in this dissertation.It exhibits the features of short axial length,short flux paths,electrical and magnetic isolation among different phases,and so on.In this dissertation,the key theoretical and technical issues for ADS-SRM are deeply and systematically studied,including the electromagnetic design and analysis method,the solutions for the torque-ripple reduction,and the modeling method of the lumped-parameter thermal network(LPTN)model.Both the simulated and experimental results are provided to verify the theoretical analysis.This work provides a theoretical and technical basis for the popularization and application of this kind of machine.The main research works in this dissertation are summarized as follows:1.The basic topology and operation principle of conventional SRM are studied,and its common control methods are analyzed.2.The novel topology of ADS-SRM is raised.The basic topology and operation principle of ADS-SRM are studied,and the feasible stator/rotor pole combinations are analyzed.Then,the electromagnetic design methodology of ADS-SRM is investigated.The magnetic field calibration coefficients in the electromagnetic design are determined by magnetic equivalent circuit(MEC)method.The output equation of ADS-SRM is deduced,and the winding design is implemented.The design flowchart of ADS-SRM is provided.Furthermore,the effects of main geometric parameters and winding layouts of ADS-SRM on the motor performance are analyzed.The optimal motor parameters are obtained on the premise of meeting the design specifications.The performance of the final design is verified by three-dimensional(3D)finite-element method(FEM).3.Two proposals of the rotor topology improvement are proposed for the torque ripple reduction of ADS-SRM.One is the rotor segment displacement,and the other is the rotor segment split.The influences of rotor shift angle and rotor-segment split sizes on the torque-production capability of ADS-SRM are analyzed,and the corresponding geometric dimentions are optimized.When studying the rotor segment displacement,the influence on the vibration characteristics of ADS-SRM is revealed and explained,and the solutions are put forward by rearranging the rotor segments.Through the comparisons of the two improved rotor topologies,the effectiveness of the two proposals in reducing the torque ripple is verified.4.The LPTN model of ADS-SRM is established,and its thermal behavior is analyzed.Aiming at the problem that the manufacturing method of the machine has a great effect on the heat transfer,the anisotropic equivalent thermal conductivities of the iron core and winding are analyzed and calculated.Aiming at the problem that the resistivity of the windings is highly temperature sensitive,the winding is divided into different parts considering the temperature gradient in the winding,and the copper losses of these parts are iterated in real time.Finally,the thermal behaviors of ADS-SRM under different speeds and load conditions are analyzed based on the developed LPTN model.5.The prototype is designed and fabricated,and the experimental verification is performed.The test platform is built.The static characteristics of the prototype,such as phase inductances,flux linkages,and static torque characteristics,as well as the load performance of the prototype are tested.Furthermore,the effectiveness of the torque ripple reduction by improving the rotor topology is verified by experiments.