Research On Structure Forms Of Modular Cascade Machines And Analysis On Interaction Of Module Motors

Electric vehicle (EV) can reduce the environment pollution, but some problemsof the drive unit regulate EV development. Modular Cascade Machines (MCM)system which comprises unit machines like batteries were presented. MCM couldexpand the high efficiency area, enhance fault tolerance capability and reduce theR&D cost. Coupled modular and MCM which using different structure form wouldaffect electric drive system. This paper does research on MCM and focuses on theproblems below:The structure form of MCM was classified from three dimensions: modulematching form, cascade coupling form, the motor structure. Features of MCM wereanalyzed in design and manufacture. Five typical structure form of MCM wasproposed. Module structure form selection principle was presented in spaceutilization, motor running range, installation dimensions. From the perspective ofapplication, design principle of radial flux multi-mode serial connection MCM andaxial flux single–mode parallel connection MCM was proposed in end cover, shaft,sensors and etc.According to the drive motor index of the system requirements,8kw powerand different base speed motors were developed and experiment was carried on;Axial and radial magnetic circuit motors were designed by same indicator. Thefeasibility of different magnetic circuit motors used in MCM was established bymain parameters comparing.In view of the problem that torque ripple of module motor would influenceeach other after cascading, cogging torque mechanism of single mode was studiedand the torque calculation formula of MCM was deduced. Cogging torque andtorque ripple interaction rules between module motors were obtained by simulation.At last, a method to weaken the influence of torque ripple was presented.Aiming at the problem that temperature field distributions influence each otherafter module motor cascade, temperature distribution of module motor and MCMwas obtained by temperature simulation. Winding temperature was not symmetric,the temperature in coupling end was high. At last, considering that temperaturewould influence efficiency, module motor efficiency was evaluated.In order to solve the problem that rotor stress distribution is affected whenlow-speed module motor was drag to work at high speed, influence of speed onstress of low-speed motor was obtained by rotor stress distribution simulation.Because torque on module motor output shaft increased after cascade, stressanalysis was carried out and low-speed module shaft as the output shaft of MCM is more suitable for the torque output.The research in subject provides a theoretical reference and analytical methodsfor MCM, lays a theoretical and experimental basis for the next step optimal designfunctional sample motor.