Study on High-Efficiency Linear Induction Motor for Transit

1.带端效应补偿器的直线感应电动机的应用当直线感应电动机的初级部件的长度受限制时，为了提高效率，解决问题的唯一方法就是对端效应进行补偿。采用磁体旋转式端效应补偿器将是最有效的补偿方法。效果和使用方法如下：(1)带补偿器的直线电机总效率至少提高5%，达到76%的值。总推力增加约40%。即可以实现具有更高效率和高密度推力的直线电机。(2)与四极补偿器相比，直径为四极补偿器的一半，体积为四极补偿器的四分之一，其补偿效果几乎相同。两极补偿器可安装在直线电机原铁芯前0.2m的空间内，长度为2.5m。(3)在制作由多个永磁体组成的补偿器磁极时，应将整个磁极一次性磁化，以免降低其应有的特性。(1)在为安全起见气隙为12mm，二次导体宽度限制为400mm的情况下，虽然较长的极距提高了效率，但极距饱和到400-500mm左右。(2)多极，运行转差小，效率高。考虑到功率因素，在40km/h的计划速度下，最小运行差约为0.07。为了获得80%的效率，需要20极的直线电机，初级长度为6m。

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.