Study On Magnetic Field Characteristic Of Permanent Magnet Synchronous Motor Driving System In Port Crane

In order to build an energy-efficient society and achieve sustainable development,efficient energy utilization strategy and a perfect energy structure are the most important.In order to realize the transformation of the energy,the demanding for the motor and its driving system in modern industry has become more and more high.Large scale cranes in port require low speed and large torque,the driving system consisting of traditional electromotor and multi-stage speed reducer is mainly used.With the discovery of various permanent magnet materials,permanent magnet motor is applied more and more widely in various fields.This paper mainly studies the application of permanent magnet motor in the driving system of large crane in port.Based on the existing related research,combining theoretical analysis and experiment,establish the simulation model of motor and electromagnetic torque model,analysis magnetic field distribution under low speed and high torque,the change regulation of electromagnetic torque and the related parameters with the degree of magnetic saturation,and the effect of magnetic saturation on the performance of the control system to reveal the generation mechanism of ‘passivation’ in the change regulation of electromagnetic torque under heavy load,and establish the mathematical model and simulation model of permanent magnet synchronous motor with the change of magnetic chain and inductance.First of all,according to the operating environment of port crane,using the design theory of permanent magnet synchronous motor,select the permanent magnet synchronous motor for the crane operation characteristics which is low speed and high torque,and establish the finite element model of motor by using RMxprt from Ansoft/Maxwell.The magnetic field of the finite element method and magnetic circuit method are compared and analyzed under the no-load and rated condition to verify the correctness of the motor model.Observing the changes in the magnetic field of the motor to analyze the structure in which the saturation degree of the magnetic field is deepest.Observing the magnetic field distribution of the motor under different magnetic saturation degrees and analyzing the characteristics of the magnetic flux change in the main parts by applying different load currents.And calculate the electromagnetic torque,inductance parameter and current voltage under different load currents.Then,based on the Id=0 vector control,combine MATLAB,study the change law of electromagnetic torque,inductance and magnetic chain at different loads by using the torque data,inductance data and magnetic chain obtained by the two dimensional transient electromagnetic field.Combined with the results of magnetic saturation analysis,study the generation mechanism of ‘passivation’ in the change regulation of electromagnetic torque under heavy load and the relationship between electromagnetic torque,armature current and magnetic chain.Finally,according to the mathematical model of inductance and magnetic chain,establish mathematical model of permanent magnet motor and control system will be simulated in the environment of MATLAB/Simulink.Combined with the characteristic of magnetic saturation which is analyzed above,different loads and rotational speeds are applied to the motor model to compare the response curves of the control system under two cases,which are neglecting magnetic saturation and considering magnetic saturation.Combined with curve,study the effect magnetic saturation on the control system.