A Torque-Optimized Control Strategy For Linear Induction Motor Drives

With the rapid growth of Linear Metro systems,LIM(Linear Induction Motor) is more and more applied all over the world.There are many advantages in using LIM,however,the most extrusive defect in LIM applying is the lower utilization ratio of a linear motor drive compared with a rotation motor drive.And it is more difficult to control because of Vertical force,end effect and parameter changes. Considering the situation of LIM applied in the linear metro,this paper proposed the research goal:maximum the output thrust under constant input power.This problem can deal with as follows:improving the structure or improving the control technique.In this paper,linear motor optimization strategy is based on the control method of rotary motor, giving full consideration to the actual operation of traction characteristics of LIM.In this paper,a dynamic mathematical model of LIM considering end-effect is derived based on the eddy current loss.Then a field orientation control scheme is developed through the analysis of the difference of linear motor and rotary motor control.The d,q-axis current control method to the objective of maximum thrust is derived constrained under the vertical force.The strategy is focused on full load control program before and after taking limiting the magnetic flux,as well as compensation program before and after taking changes in the parameters.In order to authenticate the optimization strategy,the linear motor traction drive system modeled the urban rail transit lines is set up,especially designing a circular orbit to overcome the shortcomings of traditional devices.The simulation system is based on Matlab/Simulink software.Simulation and experimental results verify the VVVF good performance of control system;optimization performance under constant parameters,as well as under varying parameters.Finally,simulation of the 4^th line of Guangzhou Metro reached a certain degree of practical value of this research.