Optimal Design And Electromagnetic Analysis Of Double Rotor Permanent Magnet Machine

In the background of energy crisis and shortage of resources,the scholars at home and abroad have paid more and more attention to the research and development of new type machine with high efficiency,energy saving and good magnetic performance.A new dual rotor machine with single stator and dual rotor structure was studied in this paper.A new dual rotor machine with single stator and dual rotor structure was studied in this paper.It has the advantages of high power density,compact structure,high core utilization and short winding ends.It can be applied to such fields as wind power generation,aviation power supply,underwater vehicle and so on.In this paper,the structure and operation principle of the dual rotor permanent magnet machine were deeply studied.Based on that,the connection modes of the dual rotor permanent magnet machine rotating in the same direction and the dual rotor permanent magnet machine rotating in the opposite direction were designed,and the equivalent analysis method for the dual rotor machine was given.In view of the complex distribution of air gap and the serious torque ripple of dual rotor permanent magnet machine,the permanent magnet of dual rotor permanent magnet machine was divided into blocks,and the internal and external magnets were arranged in reverse order Halbach.The outer Halbach magnet can enhance the inner magnetic density of the outer rotor and weaken the outer magnetic density.The inner Halbach magnet can enhance the outer magnetic density of the inner rotor and weaken the inner magnetic density,so as to improve the running efficiency of the machine,reduce the magnetic leakage and reduce the iron consumption.The parameters of the inner and outer air gap magnetic density,the cogging torque and the torque ripple were analyzed by the finite element method,and the comparison with the traditional radial magnetization method was made.Based on the energy method and Fourier decomposition,the expression of the cogging torque of the dual rotor permanent magnet synchronous machine(PMSM)was derived.In view of the special structure of the dual rotor permanent magnet machine,a method of magnetic pole shift and slot offset was studied to weaken the cogging torque of the machine.An external magnetic pole symmetric shift method was designed to reduce the external cogging torque amplitude and keep its cycle and initial phase unchanged.Then,by calculating the moving angle of the outer slot,the internal and external cogging torque is eliminated from each other through the reverse phase.Finally,the finite element method was used to verify the simulation results,and the simulation results are in agreement with the analytical results.Finally,On the basis of dual rotor permanent magnet synchronous machine,a new dual rotor hybrid excitation machine(DRHEM)with new structure was studied,which realizes the efficient combination of doubly salient electromagnetic machine(DSEM)and PMSM through single stator and double rotor structure.The matching principle of PMSM rotor pole logarithm and DSEM rotor pole number was discussed.The winding connection scheme was studied,and a new type of intermediate stator structure was designed.According to the superposition principle of the DSEM part and the PMSM part induced electromotive force,the polar arc coefficient of the DSEM rotor was adjusted to improve its induced electromotive force waveform.Finally,the feasibility and operation characteristics of the composite machine were verified by the finite element calculation.