Optimization Design And Performance Research Of Low-speed Ultra-high-efficiency Permanent Magnet Direct Drive Motor

The development of permanent magnet synchronous motor has promoted the change and renewal of redundant devices such as asynchronous motor and gear reducer in the traditional drive system,and the application of low-speed and high torque permanent magnet direct drive motor in the elevator traction system is more and more extensive.With the cancellation of the reducer,it is possible to realize the low speed direct drive load of permanent magnet synchronous motor.In this paper,a low-speed permanent magnet synchronous traction machine with a rated power of 7.5k W and an efficiency of more than 89.7% is optimally designed according to the technical indicators.In the electromagnetic calculation process,since the traditional magnetic circuit method can not analyze the multivariable strong coupling relationship in the permanent magnet traction machine by single parameter scanning,the adaptive response surface method(ARSM)is mainly used to optimize the design of eight structural variables of the traction machine.At the same time,because there is an irreconcilable relationship between weakening cogging torque and sacrificing a certain output torque when adding skewed slots or poles to the permanent magnet motor,therefore a new variable cell slope is introduced into the ARSM method for multi-objective optimization to counteract the inherent contradiction of the permanent magnet traction machine.The optimal design point and the value of cell slope are obtained by simulation calculation,and the optimal skewed pole angle is solved to verify the feasibility of the new variable.Finally,according to the optimal design point,the electromagnetic performance of the traction machine is simulated by finite element software,and the cogging torque amplitude is weakened by the cosine type uneven air gap structure and proper pole slot combination.The results show that the torque fluctuation rate of the motor based on ARSM after introducing cell slope can be reduced by 1.2%;The peak and peak value of its cogging torque can be decreased by 88.3%;Its efficiency can reach 92.49% and its operation area is wide and efficient,which meets the expected design requirements.The machine designed by this method has higher efficiency and better quality,and is more suitable for the steady operation of the elevator.