THE CONTROL OF A LINEAR MOTOR

摘要

A linear electric motor has a fixed primary comprising a stator that is divided into a number of sections, a translating secondary that has an operative length that is longer than any two adjacent sections of the stator in the form of a reaction plate, and a connecting means for connecting only those sections of the stator that are covered, either fully or partially, by the reaction plate. The stator sections are categorised in three groups - two groups of representative sections and an ordinary group of sections. The first and second representative sections alternate with ordinary sections between them. The position of the reaction plate relative to the stator is determined by monitoring current in the active representative sections. The length of the reaction plate is equal to the distance from the beginning of a first representative stator section to the end of the ordinary stator section immediately following the next second representative stator section. Power is supplied to each stator section individually, with power being supplied in a modulated manner to end active stator sections that are only partially covered by the reaction plate. Current to the first and second representative sections is used to determine the position of the stator as well as measurement of the inductance of the stator sections.