Design And Optimization Of Fault Tolerant Permanent Magnet Vernier Rim Driven Machine

In recent years,a highly integrated electric propulsion device,shaftless rim driven thruster,has emerged in the field of marine electric propulsion.Compared with traditional ship propulsion methods such as diesel propulsion and POD propulsion,shaftless rim driven thruster has the advantages of small space and high propulsion efficiency.However,as the built-in machine of the rim propeller,the more slots and poles of the permanent magnet synchronous machine will lead to the increase of magnetic flux leakage and low torque density.In addition,the use of distributed winding also leads to the lack of fault tolerance of rim driven thruster.The permanent magnet vernier machine,which is working based on flux modulation effect,has the advantages of high torque density and simple structure.In order to improve the torque density,power density and fault-tolerant capability of rim driven thruster,a fault-tolerant permanent magnet vernier rim driven machine which combined with the features of permanent magnet vernier machine,fault-tolerant machine and rim driven thruster is proposed and stuided.The research status at home and abroad of rim driven thruster and permanent magnet vernier machine is firstly analyzed.On this basis,a combined stator structure is formed with non-uniformly distributed flux modulation teeth by combing the split-tooth stator,open-slot stator and multi harmonic flux modulation effect.And the structure,features and flux modulation effect of fault-tolerant permanent magnet vernier rim driven machine is introduced.The magnetic conductivity and air gap flux density of machines with uniformly and non-uniformly distributed flux modulation poles are theoretically analyzed and verified by finite element simulation.According to the design requirements of the machine,the sizing equation is deduced,and the permanent magnet material,phase number,slot pole number and winding arrangement are determined.Then,the influence laws of key structural parameters on the back EMF and self-inductance of the motor are studied by analytical method and finite element method,and the machine is preliminarily designed.In order to get the optimal parameters quickly and accurately,the combination of Kriging response surface and multi-objective genetic algorithm is used to carry out multi-objective optimization design and finite element simulation verification of the machine.The method of coupling between circuit and field is used to study the dynamic performance of machine.The prototype of fault-tolerant permanent magnet vernier rim driven machine was manufactured and the performance test platform of the prototype was built.The no-load and load experiments were also carried out.The results show that compared with the traditional rim driven machine,the optimized fault-tolerant permanent magnet vernier rim driven machine has higher torque density,better fault-tolerant capability and less power loss.The test results of the prototype are basically consistent with the finite element simulation results,which verifies the effectiveness of the motor structure and optimization design method proposed in this thesis.