Research On Direct Drive Permanent Magnet Motor Transmission System For Air-jet Loom

The transmission structure of the air-jet loom is mainly composed of asynchronous motors and pulleys nowadays.The transmission structure has disadvantages such as large volume,low efficiency,severe wear,and difficulty in achieving flexible speed change of the main shaft.Therefore,it is necessary to improve and upgrade the transmission structure.The usage of a permanent magnet motor direct drive system can simplify the transmission structure and eliminate the deceleration components,however,it puts forward higher requirements for the smoothness of torque output.This thesis focuses on the direct-drive permanent magnet motor transmission system for air-jet loom,and conducts an in-depth analysis of its torque stability.The main research contents are as follows.The permanent magnet motor direct drive system is used to replace the traditional twostage transmission structure,within a deep insight of the research and deign of the motor's electromagnetic,the general law of the direct drive permanent magnet motor design for air-jet loom is explored,and and the influence of different pole-slot combination on back EMF,harmonic content,cogging torque and output torque are studied.The thesis also investigates the influence of the combination of uneven air gap and arc-shaped slot opening at the maximum air gap on the harmonic content,cogging torque,output torque,etc.,and uses the taguchi method to optimize the analysis.Hence,further studies the influence of stator notch width and skew angle on the output torque stability.The research and analysis are carried focusing on the starting performance of the motor.With the assurance of meeting the requirements of ensuring that the operating performance and mechanical strength,the rotor and shaft are designed to reduce the weight,thereby reducing the rotor moment of inertia and improving its dynamic performance,especially the starting performance;the thesis also builds a vector control model,and uses vector control method to compare and analyze the starting performance of the motor before and after weight reduction based on the matlab/Simulink module.The loss of each part of the motor are calculated,the temperature field of the motor under the determined cooling conditions are analyzed,and the mechanical strength of the rotor after weight reduction are checked to meet the safe and reliable operation of the motor.Combined with the equipment manufacturing project of a textile machinery factory in Zhejiang,a prototype with a rated power of 3k W and a rated speed of 800r/min was developed.The prototype test proved the feasibility of the permanent magnet motor direct-drive for the air-jet loom and the content of this thesis.The correctness has certain reference value for the future research and analyze of direct-drive permanent magnet motors for air-jet looms.