离散电流控制在地铁永磁牵引系统中的应用

Application of Discrete Current Control in Metro Permanent Magnet Traction System

在地铁永磁牵引系统中,输出电压较高、电流较大,开关损耗和散热等条件受到限制,牵引逆变器的最高开关频率通常只有几百赫兹,而地铁永磁同步电机(PMSM)的调速范围较宽,输出频率可达300 Hz,载波比的变化范围较大。在这种情况下,常规电流比例积分(PI)控制器性能较差,难以满足系统要求。为此,根据复矢量分析方法,建立了包含延时影响的离散数学模型,在此基础上,设计离散电流控制器。通过仿真及在西安地铁2号线装车进行试验,试验结果表明基于复矢量的离散电流控制器在地铁PMSM运行过程中具有较好的动态及稳态性能,转矩(励磁)反馈电流均能较好地跟随转矩(励磁)给定电流,并且在牵引、制动过程中,电压和电流稳定变化,无明显振荡。

In the subway permanent magnet traction system,the output voltage is high,the current is large,and the switching loss and heat dissipation are limited,the highest switching frequency of the traction inverter is usually only a few hundred Hertz,while the speed range of the subway permanent magnet synchronous motor(PMSM)is wide,the output frequency is up to 300 Hz,and the carrier ratio varies in a large range.In this case,the performance of conventional current proportional integration(PI)controller is poor and it is difficult to meet the requirements of the system.Based on the complex vector method,a discrete mathematical model containing the delay effect is established,and a discrete current controller is designed.Through simulation and test in Xi’an metro line 2,the test results show that the discrete current control based on complex vector has better dynamic and steady-state performance in the operation process of metro PMSM,and the torque(excitation)feedback current can better follow the torque(excitation)given current.In the process of traction and braking,the voltage and current change steadily without obvious oscillation.