Study on High-Efficiency Linear Induction Motor for Transit

1.带端部效应补偿器的直线感应电动机的使用当直线感应电动机的初级构件被限制在目前的长度时，为提高效率而留下的唯一解决问题的手段就是补偿端部效应。采用磁转子式端部效应补偿器将是最有效的方法。结果表明：（1）采用该补偿器后，直线电机的总效率至少提高了5%，最高可达76%。总推力增加约40%。即，能够实现效率更高、推力密度更高的线性电动机。（2）双极补偿器的直径是四极补偿器的一半，体积是四极补偿器的四分之一，其补偿效果几乎相同。在长度为2.5m的直线电机初级铁芯前0.2m的空间内可安装两极补偿器。(3)In 2.具有长初级构件的直线感应电动机的使用（1）在为了安全而将气隙设为12 mm、次级导体的宽度限定为400 mm的条件下，极距饱和到大约400- 500 mm，尽管较长的极距增加了效率。（2）极数多，实现小的运行滑差，效率高。考虑到功率因数，在计划速度为40 km/h时，最小运行滑差约为0.07。为了获得80%的效率，需要20极和初级长度为6 m的直线电机。

1.Use of linear induction motor with end-effect compensatorWhen the primary member of linear induction motor is restricted to the present length, the only means to solve the problem left for higher efficiency is to compensate the end-effect. It will be the most effective method to use the magnet rotator type of end-effect compensator. The effect and the technique to use are as follow:(1)The overall efficiency of linear motor with the compensator increases by 5% at least and increases to the value of 76%. The overall thrust increases by about 40%. That is, the linear motor with higher-efficiency and high-density thrust can be realized.(2)The two-pole compensator, whose diameter is half and the volume is one forth as compared to the four-pole compensator, has almost the same effect for the compensation. The two-pole compensator can be equipped in the space of 0.2m in front of the primary core of linear motor with the length of 2.5m.(3)In making the magnet pole of compensator formed with plural permanent magnets, the whole of pole should be magnetized in lump sum not to decrease the proper characteristics.2.Use of linear induction motor with long primary member(1)In the conditions that the air gap is 12mm for the safety and the width of secondary conductor is limited to 400mm, the pole pitch is saturated to about 400-500mm though the longer pole pitch increases the efficiency.(2)Large number of poles realize the small operating slip for higher efficiency. The minimum operating slip will be about 0.07 at the schedule speed of 40km/h taking into consideration of the power factor. To obtain the efficiency of 80%, the linear motor with twenty poles and the primary length of 6m is necessary.