Design And Optimization Of A High-speed Permanent Magnet Synchronous Machine For Gas Compressors

In the fields of fuel cells and compressed air energy storage,centrifugal air compressors directly driven by high-speed machines are considered to be the most potential development direction and become a research hotspot in the field.Due to the lack of corresponding high-speed machine products,the research and development work of high-speed centrifugal air compressors are restricted.The high-speed permanent magnet synchronous machine is widely used in the field of high speed driving,due to its high power density,high efficiency,and large high-efficiency speed range.Therefore,in order to meet high-speed demand,this dissertation has carried out research on the design,analysis and optimization methods of high-speed permanent magnet synchronous machines.In this dissertation,the topologies of high-speed permanent magnet machines are studied.According to the design indexes of high-speed machines,the structure and size of the stator and rotor are designed.Based on the structural stress analysis,the material and size of the permanent magnet sheath are discussed.Furthermore,the relationship between the minimum thickness of the sheath and the material characteristics is obtained.As the same time,according to the performance and loss of the machine with different permanent magnet structures,the PMs are mounted on the surface of the rotor.the influence of different winding structures on the length of the wire and the copper loss of the machine is analyzed.The finite element model of the machine is established to prove that the design requirements are realized.The loss analysis method of the high-speed machine is calculated to obtain the proposed machine losses.Then,feasible measures to reduce the loss are proposed based on the structure of the machine.In addition,considering the structure of the machine,feasible measures to reduce losses and increase power density are proposed in this dissertation.By comparing the copper loss of the machine under different wire diameter winding schemes,the optimal wire diameter design is obtained to reduce the copper loss.Based on the machine optimization process,the combination of the machine interpolation model and the genetic algorithm is used to optimize the machine parameters,which the wind friction loss is reduced by17.2% and the machine power density is increased by 6.64%.The machine efficiency is also slightly improved by the optimization.On the basis of the foregoing analysis,the temperature field of the machine has been studied in this dissertation,analyzes the effect of temperature on the performance and loss of the machine,and designs the heat dissipation structure of the machine.Two heat dissipation schemes including conventional spiral water channel and the proposed axial water channel are proposed.The heat dissipation effect of the two schemes is evaluated based on the one-way coupling method and the two-way indirect coupling method.The results show that the two heat dissipation schemes can satisfy the work of the machine.Furthermore,the heat dissipation effect of the axial water channel design combined with the special structure of the machine is better than that of the conventional spiral water channel.At the same time,the iterative two-way coupling calculation result is more accurate compared with the one-way coupling calculation.