Research On The Permanent Magnet Brushless Drive System For Rail Transit Door

Rail transit vehicle technology has advanced a lot as a result of rapid development of urban rail transit.Square wave current is chosen as a way to drive the brushless direct current motor(BLDCM)commonly used in transit door system nowadays,which has some problems such as large torque ripple and noise.This paper mainly studies the position estimation strategies based on the switch-type Hall-effect sensor of permanent magnet synchronous motor(PMSM),to realize the high performance vector control,and applies them to the rail transit door system.First,this paper analyzes the implementation methods of square wave control and vector control of permanent magnet motor.Aiming at improving the accuracy of rotor position and speed estimation,sections of three Hall signals are divided based on six discrete positions in an electric cycle.The angular fine division is carried out,and the related theoretical analysis is made on the average speed method and the second-order method with the introduction of acceleration.Then,in order to further improve the accuracy of the estimation results,the position vector tracking observer based on the back electromotive force(EMF)method is proposed,and the back EMF is estimated by the sliding model variable structure control.Based on the mathematical analysis,the structure of the observer is analyzed and designed.Next,considering the continuous changes of the operation states of the rail transit door system,this paper analyzes the forces of the door in the process of opening and closing,establishes its dynamic model,its closing curve is designed as well.For the commonly used plug-in structure door in rail transit,it analyzes the impacts of the rail angle and air conditioning supply volume on its resistance and operation states,and the position estimation algorithm of hall sensor is used in the vector control of the door driving motor,which makes the research more practical.Finally,simulation models of position estimation and door system are built in Matlab/Simulink,the hardware platform of PMSM vector control based on STM32F103 is also built,and the corresponding software is designed.The simulation and experimental results show that the strategies of position and speed estimation based on the switch-type Hall-effect sensor are correct and feasible,and they can be applied to the rail transit door system to achieve the safe and effective control of the door body.