Research On Near Pole Slot Direct Drive Permanent Magnet Motor For Stacker

Along with the rapid development of the logistics industry,increasingly higher requirements for automation has been put forward,and stereoscopic warehouse has been applied more and more widely.In the automatic stereoscopic warehouse,cargo transport units are mainly composed of the stacker,conveying line and self-guided trolley.Wherein,the stacker is the equipment which runs the most frequently.The traditional stacker is driven by the asynchronous motor and the reducer.This driving way has some problems like low efficiency,poor precision and unreliable operation.However,low-speed direct-drive permanent magnet motor has some advantages like high efficiency,large torque at a low speed and no need for the reduction gear box.Thus,a stacker dedicated low-speed direct-drive permanent magnet motor is designed in this thesis based on the research background of stereoscopic warehouse dedicated stacker.The electromagnetism,loss and temperature field of the designed motor are analyzed,and the following researches are mainly carried out:(1)Looked up domestic and overseas literatures regarding structure design of the proximal pole slot direct-drive permanent magnet motor,calculation of the cogging torque,calculation of temperature rise and loss and application of the permanent magnet motor in the automatic warehouse.Determined the main dimensions of the motor,winding and rotor structure of the motor according to the actual requirements of the stacker for the drive motor by making use of the magnetic circuit and analyzed the motor performance under different pole slot ratios.(2)Analyzed main influencing factors of the cogging torque of the motor with the finite element software according to the inherent problem of large cogging torque of proximal pole slot direct-drive permanent magnet motor.The specific contents are as follows: Influence of different pole slot ratios on cogging torque;Influence of pole-arc coefficient on cogging torque;Influence of different pole-arc coefficients on cogging torque;Influence of the chute on cogging torque of motor.Optimized the motor according to the analysis result,carried out simulation verification of performance of the optimized motor,including counter-electromotive force,air gap flux density and torque,and determined the final structure of the motor.(3)Since the direct-drive permanent magnet motor in the stacker is driven by the frequency converter,Matlab software was applied to simulate the motor current waveform of the frequency converter in the case of power supply and this waveform was introduced into Maxwell to calculate loss of the motor when the frequency converter was supplied with power.Considering the actual application of the motor in the stacker,natural cooling was applied to the motor.Temperature field simulation analysis of the motor was carried out according to the calculated loss.Analysis results indicate that the designed motor can meet the requirement of temperature rise.